Sedimentological and diagenetic patterns of anhydrite deposits in the Badenian evaporite basin of the Carpathian Foredeep, southern Poland

NASA Astrophysics Data System (ADS)

Kasprzyk, Alicja

2003-05-01

Anhydrite deposits are widely distributed in the Middle Miocene Badenian evaporite basin of Poland, including the marginal sulphate platform and adjacent salt depocenter. Particular sedimentological, petrographic and geochemical characteristics of these anhydrite deposits and especially common pseudomorphic features, inherited from the precursor gypsum deposits, allow the interpretation of the original sedimentary facies. The observed facies distribution and succession (lower and upper members) reveal three distinct facies associations that record a range of depositional environments from nearshore to deeper basinal settings. Platform sulphates were deposited in subaerial and shallow-marine environments (shoreline and inner platform-lagoon system) mainly as autochthonous selenitic gypsum. This was reworked and redistributed into deeper waters (outer platform-lagoon, slope and the proximal basin floor system) to form resedimented facies composed mostly of allochthonous clastic gypsum and minor anhydrite. The general variation in petrographic and geochemical compositions of anhydrite lithofacies of the lower and upper members reflects the brine evolution, as the result of interactions between seawater, meteoric runoff and highly saline, residual pore fluids. The results indicate the importance of synsedimentary and diagenetic anhydritisation processes in formation of the Badenian anhydrite lithofacies, all of which preserve the original depositional features of the former gypsum. This also applies to the basinal anhydrite previously interpreted to have a depositional genesis. Two different genetic patterns of anhydrite have been reinforced by this study: (1) synsedimentary anhydritisation of gypsum deposits by highly concentrated brines or elevated temperatures in surficial to shallow-burial environments (lower member), and (2) successive phases (syndepositional de novo growth, early diagenetic to late diagenetic replacement of former gypsum) of anhydrite formation during progressive burial (upper member).

Biological influences on modern sulfates: Textures and composition of gypsum deposits from Guerrero Negro, Baja California Sur, Mexico

NASA Astrophysics Data System (ADS)

Vogel, Marilyn B.; Des Marais, David J.; Parenteau, Mary N.; Jahnke, Linda L.; Turk, Kendra A.; Kubo, Michael D. Y.

2010-01-01

Gypsum (CaSO 4·2H 2O) deposits from a range of sedimentary environments at Guerrero Negro, Baja California Sur, Mexico were investigated for microscale texture and composition in order to differentiate features formed under substantial microbial influence from those for which microbial effects were relatively minor or absent. Gypsum deposits were classified according to their sedimentary environment, textures, crystal habit, brine composition and other geochemical factors. The environments studied included subaqueous sediments in anchialine pools and in solar salterns, as well as subsurface sediments of mudflats and saltpans. Gypsum that developed in the apparent absence of biofilms included crystals precipitated in the water column and subsedimentary discs that precipitated from phreatic brines. Subsedimentary gypsum developed in sabkha environments exhibited a sinuous microtexture and poikilitically enclosed detrital particles. Water column precipitates had euhedral prismatic habits and extensive penetrative twinning. Gypsum deposits influenced by biofilms included bottom nucleated crusts and gypsolites developing in anchialine pools and saltern ponds. Gypsum precipitating within benthic biofilms, and in biofilms within subaerial sediment surfaces provided compelling evidence of biological influences on crystal textures and habits. This evidence included irregular, high relief surface textures, accessory minerals (S°, Ca-carbonate, Sr/Ca-sulfate and Mg-hydroxide) and distinctive crystal habits such as equant forms and crystals having distorted prism faces.

Site Formation Processes and Hunter-Gatherers Use of Space in a Tropical Environment: A Geo-Ethnoarchaeological Approach from South India

PubMed Central

Friesem, David E.; Lavi, Noa; Madella, Marco; Ajithprasad, P.; French, Charles

2016-01-01

Hunter-gatherer societies have distinct social perceptions and practices which are expressed in unique use of space and material deposition patterns. However, the identification of archaeological evidence associated with hunter-gatherer activity is often challenging, especially in tropical environments such as rainforests. We present an integrated study combining ethnoarchaeology and geoarchaeology in order to study archaeological site formation processes related to hunter-gatherers’ ways of living in tropical forests. Ethnographic data was collected from an habitation site of contemporary hunter-gatherers in the forests of South India, aimed at studying how everyday activities and way of living dictate patterns of material deposition. Ethnoarchaeological excavations of abandoned open-air sites and a rock-shelter of the same group located deep in the forests, involved field observations and sampling of sediments from the abandoned sites and the contemporary site. Laboratory analyses included geochemical analysis (i.e., FTIR, ICP-AES), phytolith concentration analysis and soil micromorphology. The results present a dynamic spatial deposition pattern of macroscopic, microscopic and chemical materials, which stem from the distinctive ways of living and use of space by hunter-gatherers. This study shows that post-depositional processes in tropical forests result in poor preservation of archaeological materials due to acidic conditions and intensive biological activity within the sediments. Yet, the multiple laboratory-based analyses were able to trace evidence for activity surfaces and their maintenance practices as well as localized concentrations of activity remains such as the use of plants, metals, hearths and construction materials. PMID:27783683

Sedimentary record of erg migration

NASA Astrophysics Data System (ADS)

Porter, M. L.

1986-06-01

The sedimentary record of erg (eolian sand sea) migration consists of an idealized threefold division of sand-sea facies sequences. The basal division, here termed the fore-erg, is composed of a hierarchy of eolian sand bodies contained within sediments of the flanking depositional environment. These sand bodies consist of eolian strata deposited by small dune complexes, zibars, and sand sheets. The fore-erg represents the downwind, leading edge of the erg and records the onset of eolian sedimentation. Basin subsidence coupled with erg migration places the medial division, termed the central erg, over the fore-erg strata. The central erg, represented by a thick accumulation of large-scale, cross-stratified sandstone, is the product of large draa complexes. Eolian influence on regional sedimentation patterns is greatest in the central erg, and most of the sand transported and deposited in the erg is contained within this region. Reduction in sand supply and continued erg migration will cover the central-erg deposits with a veneer of back-erg deposits. This upper division of the erg facies sequence resembles closely the fore-erg region. Similar types of eolian strata are present and organized in sand bodies encased in sediments of the upwind flanking depositional environment(s). Back-erg deposits may be thin due to limited eolian influence on sedimentation or incomplete erg migration, or they may be completely absent because of great susceptibility to postdepositional erosion. Tectonic, climatic, and eustatic influences on sand-sea deposition will produce distinctive variations or modifications of the idealized erg facies sequence. The resulting variants in the sedimentary record of erg migration are illustrated with ancient examples from western North America, Europe, southern Africa, and South America.

Permian of Southeast Asia: an overview

NASA Astrophysics Data System (ADS)

Fontaine, Henri

2002-08-01

Permian rocks are widely distributed throughout Southeast Asia. Because of the tropical-equatorial climate the rocks are commonly deeply weathered and covered by dense vegetation over much of the region. Elsewhere, Permian rocks are well exposed and easy to access, particularly where limestone outcrops have weathered to form spectacular, castellated, tower karst. Many limestone outcrops, containing abundant fusulinaceans, were early recognized to be of Permian age, but many outcrops without fusulinaceans, erroneously assigned to the Permian, were found subsequently to be of Triassic age, and more careful studies have established the Permian age of rocks of other lithologies. It is now recognized that different depositional environments are represented by the Permian deposits in various parts of the region. Massive limestones, widespread throughout the region, represent extensive carbonate platforms; local occurrences of thick bedded cherts indicate deposition in deep marine environments, coal, bauxite and clastic sediments with vertebrate remains in North Vietnam and Laos indicate deposition in a continental environment, and pebbly mudstones in Myanmar, Peninsular Thailand, northwest Malaysia and Sumatra, are considered to have been formed in a glacial environment. Volcanic rocks are absent in northwest Peninsular Malaysia and Peninsular Thailand, but are extensively developed in North Vietnam, Sumatra, the eastern Malay Peninsula and Timor. Fossils, representing many fossil groups, are often prolific in Permian sediments, with fusulinaceans, for example, occurring in astronomical numbers in many limestone outcrops. Age-diagnostic fossils demonstrate that the whole of the Permian is represented in different areas of Southeast Asia. Fossil faunal and floral assemblages have been used to establish climatic conditions and environments of deposition, to define distinct crustal blocks and to provide the basis for reconstructing the palaeogeography during Permian times.

Soil variability and landscape history of the last 800.000 years revealed by the horsification of the landscape in North-Brabant, The Netherlands

NASA Astrophysics Data System (ADS)

Kluiving, Sjoerd; Kok, Marielle; van Suijlekom, Jan-Jaap; Kasse, Kees

2015-04-01

In the province of North-Brabant in the southern Netherlands a diverse geological substrate is present variable in chronology, sediment properties, and soil profiles. The human influence on soil quality and topography has a history of millennia while new developments related to the horsification of the landscape in this region allow an insight in the soil patterns with associated landscape evolution. The objective in this project is to show that records of soils and landscape in this area are able to demonstrate the evolutional history and disseminate the pedological and geological knowledge to a wider audience in demonstrating that soil records and associated landscape evolution reveal a regional identity that can be very useful to apply in landscape architectural projects, such as in the horsification of the landscape. Soil records show landscape evolution has progressed in three distinct phases: 1) The oldest deposits in the region are formed by river sediments that reflect a fluvial environment that was present 800.000 years ago in the Lower-Pleistocene. Old courses of the rivers Rhine and Meuse deposited gravelly white sands and clay layers that have a distinct effect on hydrological properties. 2) Eolian sands dating from the Late Glacial, deposited 12.000-14.000 years before present were deposited by western wind directions, obvious from large scale linear and parabolic dune ridges. These sandy deposits have endured soil acidification and podzolisation resulting in classic Umbric Podzol profiles testifying of a prolonged period of landscape evolution. 3) Tree removal in the Holocene by man created unprotected open sand plains that were eroded and deposited by wind processes in small scale ridges with steep slopes up till approximately 500 years ago. These drift sands have a widespread occurrence and can be recognized in thin micro-podzol profiles in association with a distinct morphology of steep sloped dunes. Multiple soil horizons reflect different time periods elapsed and specific 'open landscape' environments, as these thin podzolic horizons testify. Future research will involve cartographic mapping by soil coring, as well as OSL dating, next to an ecological field reconnaissance. In this poster we will show how the soil in this region beholds an entire landscape history, and how that information can be combined with nature development in landscape architectural plans.

Evidence for a palaeo-subglacial lake on the Antarctic continental shelf

PubMed Central

Kuhn, Gerhard; Hillenbrand, Claus-Dieter; Kasten, Sabine; Smith, James A.; Nitsche, Frank O.; Frederichs, Thomas; Wiers, Steffen; Ehrmann, Werner; Klages, Johann P.; Mogollón, José M.

2017-01-01

Subglacial lakes are widespread beneath the Antarctic Ice Sheet but their control on ice-sheet dynamics and their ability to harbour life remain poorly characterized. Here we present evidence for a palaeo-subglacial lake on the Antarctic continental shelf. A distinct sediment facies recovered from a bedrock basin in Pine Island Bay indicates deposition within a low-energy lake environment. Diffusive-advection modelling demonstrates that low chloride concentrations in the pore water of the corresponding sediments can only be explained by initial deposition of this facies in a freshwater setting. These observations indicate that an active subglacial meltwater network, similar to that observed beneath the extant ice sheet, was also active during the last glacial period. It also provides a new framework for refining the exploration of these unique environments. PMID:28569750

Evaluation of conditions along the grounding line of temperate marine glaciers: An example from Muir Inlet, Glacier Bay, Alaska

USGS Publications Warehouse

Seramur, K.C.; Powell, R.D.; Carlson, P.R.

1997-01-01

In the marine environment, stability of the glacier terminus and the location of subglacial streams are the dominant controls on the distribution of grounding-line deposits within morainal banks. A morainal bank complex in Muir Inlet, Glacier Bay, SE Alaska, is used to develop a model of terminus stability and location of subglacial streams along the grounding line of temperate marine glaciers. This model can be used to interpret former grounding-line conditions in other glacimarine settings from the facies architecture within morainal bank deposits. The Muir Inlet morainal bank complex was deposited between 1860 A.D. and 1899 A.D., and historical observations provide a record of terminus positions, glacial retreat rates and sedimentary sources. These data are used to reconstruct the depositional environment and to develop a correlation between sedimentary facies and conditions along the grounding line. Four seismic facies identified on the high-resolution seismic-reflection profiles are used to interpret sedimentary facies within the morainal bank complex. Terminus stability is interpreted from the distribution of sedimentary facies within three distinct submarine geomorphic features, a grounding-line fan; stratified ridges, and a field of push ridges. The grounding-line fan was deposited along a stable terminus and is represented on seismic-reflection profiles by two distinct seismic facies, a proximal and a distal fan facies. The proximal fan facies was deposited at the efflux of subglacial streams and indicates the location of former glacifluvial discharges into the sea. Stratified ridges formed as a result of the influence of a quasi-stable terminus on the distribution of sedimentary facies along the grounding line. A field of push ridges formed along the grounding line of an unstable terminus that completely reworked the grounding-line deposits through glacitectonic deformation. Between 1860 A.D. and 1899 A.D. (39 years), 8.96 x 108 m3 of sediment were deposited within the Muir Inlet morainal bank complex at an average annual sediment accumulation rate of 2.3 x 107 m3/a. This rate represents the annual sediment production capacity of the glacier when the Muir Inlet drainage basin is filled with glacial ice.

Return to the Taung cave paradigm.

PubMed

McKee, Jeffrey K

2016-02-01

The Taung hominin fossil was recovered in 1924 during quarry operations in the tufa formations of the Buxton Limeworks. Reconstructions of the depositional environment of the juvenile Australopithecus skull have concentrated on the types of caves that form within the tufa. Hopley et al. (Am J Phys Anthropol 151 (2013) 316-324) proposed a new model in which the pink carbonate deposits, in which many of the Taung fossils are found, formed as open terrestrial pedogenic deposits. The objective here is to challenge that notion. Observations of the depositional environments at Taung are based upon the University of the Witwatersrand paleontological excavations at the Buxton Limeworks from 1988 to 1993, and subsequent laboratory analysis of the fossils and sediments. Hopley et al. (Am J Phys Anthropol 151 (2013) 316-324) conflate numerous distinct outcroppings of the pink carbonates as a single "unit." The excavations revealed numerous fossiliferous deposits that differ greatly in taphonomic origins and formation processes, and that cannot be considered a "unit" despite the commonality of pink carbonates. There are deposits that fit the model proposed by Hopley et al. (Am J Phys Anthropol 151 (2013) 316-324), but they are not the ones that yielded the most significant fossils. Most of the fossiliferous deposits, including those most likely to have yielded the Taung hominin, are best reconstructed as being of karst origins. © 2015 Wiley Periodicals, Inc.

Lakshmi Planum, Venus - Characteristics and models of origin

NASA Technical Reports Server (NTRS)

Roberts, Kari M.; Head, James W.

1990-01-01

The distinctive and unique Venusian geological structure, Lakshmi Planum, is an expansive relatively smooth flat plateau containing two large shield volcanos and abundant volcanic plains in the midst of a region of extreme relief. The characteristics which distinguish Lakshmi from other volcanic regions known on the planet, such as Beta Regio, are identified. These include its high altitude and plateaulike nature; the presence of two very large low shield structures with distinctive central paterae and long radiating flows; and its compressional tectonic environment. The detailed nature and significance of the volcanic deposits on Lakshmi are determined; the erruption styles and conditions are interpreted; and the link between the observed volcanism and tectonic environment of the region is discussed. Models for the formation of Lakshmi Planum are presented and evaluated.

Lakshmi Planum, Venus - Characteristics and models of origin

NASA Astrophysics Data System (ADS)

Roberts, Kari M.; Head, James W.

1990-12-01

The distinctive and unique Venusian geological structure, Lakshmi Planum, is an expansive relatively smooth flat plateau containing two large shield volcanos and abundant volcanic plains in the midst of a region of extreme relief. The characteristics which distinguish Lakshmi from other volcanic regions known on the planet, such as Beta Regio, are identified. These include its high altitude and plateaulike nature; the presence of two very large low shield structures with distinctive central paterae and long radiating flows; and its compressional tectonic environment. The detailed nature and significance of the volcanic deposits on Lakshmi are determined; the erruption styles and conditions are interpreted; and the link between the observed volcanism and tectonic environment of the region is discussed. Models for the formation of Lakshmi Planum are presented and evaluated.

Deconvolving the Fate of Carbon in Coastal Sediments

NASA Astrophysics Data System (ADS)

Van der Voort, Tessa S.; Mannu, Utsav; Blattmann, Thomas M.; Bao, Rui; Zhao, Meixun; Eglinton, Timothy I.

2018-05-01

Coastal oceans play a crucial role in the global carbon cycle, and are increasingly affected by anthropogenic forcing. Understanding carbon cycling in coastal environments is hindered by convoluted sources and myriad processes that vary over a range of spatial and temporal scales. In this study, we deconvolve the complex mosaic of organic carbon manifested in Chinese Marginal Sea (CMS) sediments using a novel numerical clustering algorithm based on 14C and total OC content. Results reveal five regions that encompass geographically distinct depositional settings. Complementary statistical analyses reveal contrasting region-dependent controls on carbon dynamics and composition. Overall, clustering is shown to be highly effective in demarcating areas of distinct organic facies by disentangling intertwined organic geochemical patterns resulting from superimposed effects of OC provenance, reworking and deposition on a shelf region exhibiting pronounced spatial heterogeneity. This information will aid in constraining region-specific budgets of carbon burial and carbon cycle processes.

Triple oxygen isotopes indicate urbanization affects sources of nitrate in wet and dry atmospheric deposition

NASA Astrophysics Data System (ADS)

Nelson, David M.; Tsunogai, Urumu; Ding, Dong; Ohyama, Takuya; Komatsu, Daisuke D.; Nakagawa, Fumiko; Noguchi, Izumi; Yamaguchi, Takashi

2018-05-01

Atmospheric nitrate deposition resulting from anthropogenic activities negatively affects human and environmental health. Identifying deposited nitrate that is produced locally vs. that originating from long-distance transport would help inform efforts to mitigate such impacts. However, distinguishing the relative transport distances of atmospheric nitrate in urban areas remains a major challenge since it may be produced locally and/or be transported from upwind regions. To address this uncertainty we assessed spatiotemporal variation in monthly weighted-average Δ17O and δ15N values of wet and dry nitrate deposition during one year at urban and rural sites along the western coast of the northern Japanese island of Hokkaido, downwind of the East Asian continent. Δ17O values of nitrate in wet deposition at the urban site mirrored those of wet and dry deposition at the rural site, ranging between ˜ +23 and +31 ‰ with higher values during winter and lower values in summer, which suggests the greater relative importance of oxidation of NO2 by O3 during winter and OH during summer. In contrast, Δ17O values of nitrate in dry deposition at the urban site were lower (+19 - +25 ‰) and displayed less distinct seasonal variation. Furthermore, the difference between δ15N values of nitrate in wet and dry nitrate deposition was, on average, 3 ‰ greater at the urban than rural site, and Δ17O and δ15N values were correlated for both forms of deposition at both sites with the exception of dry deposition at the urban site. These results suggest that, relative to nitrate in wet and dry deposition in rural environments and wet deposition in urban environments, nitrate in dry deposition in urban environments forms from relatively greater oxidation of NO by peroxy radicals and/or oxidation of NO2 by OH. Given greater concentrations of peroxy radicals and OH in cities, these results imply that dry nitrate deposition results from local NOx emissions more so than wet deposition, which is transported longer distances. These results illustrate the value of stable isotope data for distinguishing the transport distances and reaction pathways of atmospheric nitrate pollution.

Morphologic and hydrodynamic controls on the occurrence of tidal bundles in an open-coast macrotidal environment, northern Gyeonggi Bay, west coast of Korea

NASA Astrophysics Data System (ADS)

Choi, Kyungsik; Kim, Do Hyeong

2016-06-01

Tidal dunes with well-defined rhythmic tidal bundles are documented from the lower intertidal zone of an open-coast macrotidal environment in Gyeonggi Bay, Korea. Based on combined morphologic, sedimentologic and hydrodynamic datasets, this study aims to characterize the factors that govern the temporal and spatial variability of tidal bundles in a non-barred, unconfined macrotidal environment. The tidal dunes are flood-asymmetric and of longer wavelength (10-20 m) with small ebb caps on the upper bank, and symmetric to slightly ebb-asymmetric and of shorter wavelength (5-10 m) with larger ebb caps on the lower bank. The upper-bank dunes are characterized by more steeply dipping flood-directed planar cross-beds and thinner mud drapes than the lower-bank dunes. Each tidal bundle consists of a single mud drape that is stratified to cross-stratified, rich in silt and very fine sand. It overlies ebb-directed ripples and represents dynamic mud deposition during the ebb tidal phase. The presence of strong rotary currents (up to 0.25 m/s) and low suspended-sediment concentration of flood currents prevent deposition of mud drapes during the high-tide slack-water period. The distinct asymmetry in the water elevation at which the velocity peaks during the ebb and flood phases results in the preferential preservation of flood-directed cross-beds in the lower intertidal zone, where the ebb current - although stronger than the flood currents - is of shorter duration and hence unable to reverse the dune profile. The pronounced time-velocity asymmetry at the higher elevation combined with the distinct velocity peak asymmetry leads to a better preservation of hierarchical tidal cycles in the upper-bank dunes. The present study suggests that the persistent occurrence of single, stratified to cross-stratified mud drapes, which reflect dynamic mud deposition during the ebb phase, and the dominance of flood-directed cross-beds are diagnostic features of tidal bundles in the intertidal zone of unbarred, open-coast macrotidal environments. A proposed model for mud drape deposition provides a new perspective on the origin of tidal bundles together with useful criteria for reconstructing the paleo-depositional setting.

Bacterial Composition and Survival on Sahara Dust Particles Transported to the European Alps

PubMed Central

Meola, Marco; Lazzaro, Anna; Zeyer, Josef

2015-01-01

Deposition of Sahara dust (SD) particles is a frequent phenomenon in Europe, but little is known about the viability and composition of the bacterial community transported with SD. The goal of this study was to characterize SD-associated bacteria transported to the European Alps, deposited and entrapped in snow. During two distinct events in February and May 2014, SD particles were deposited and promptly covered by falling snow, thus preserving them in distinct ochre layers within the snowpack. In June 2014, we collected samples at different depths from a snow profile at the Jungfraujoch (Swiss Alps; 3621 m a.s.l.). After filtration, we performed various microbiological and physicochemical analyses of the snow and dust particles therein that originated in Algeria. Our results show that bacteria survive and are metabolically active after the transport to the European Alps. Using high throughput sequencing, we observed distinct differences in bacterial community composition and structure in SD-layers as compared to clean snow layers. Sporulating bacteria were not enriched in the SD-layers; however, phyla with low abundance such as Gemmatimonadetes and Deinococcus-Thermus appeared to be specific bio-indicators for SD. Since many members of these phyla are known to be adapted to arid oligotrophic environments and UV radiation, they are well suited to survive the harsh conditions of long-range airborne transport. PMID:26733988

Use of geochemical signatures, including rare earth elements, in mosses and lichens to assess spatial integration and the influence of forest environment

NASA Astrophysics Data System (ADS)

Gandois, L.; Agnan, Y.; Leblond, S.; Séjalon-Delmas, N.; Le Roux, G.; Probst, A.

2014-10-01

In order to assess the influence of local environment and spatial integration of Trace Metals (TM) by biomonitors, Al, As, Cd, Cr, Cs, Cu, Fe, Mn, Ni, Pb, Sb, Sn, V and Zn and some rare earth element (REE) concentrations have been measured in lichens and mosses collected in three French forest sites located in three distinct mountainous areas, as well as in the local soil and bedrock, and in both bulk deposition (BD) and throughfall (TF). Similar enrichment factors (EF) were calculated using lichens and mosses and local bedrock for most elements, except for Cs, Mn, Ni, Pb, and Cu which were significantly (KW, p < 0.05) more enriched in mosses. Similar REE ratios were measured in soils, bedrock, lichens and mosses at each study sites, indicating a regional integration of atmospheric deposition by both biomonitors. Both TM signature and REE composition of mosses revealed that this biomonitor is highly influenced by throughfall composition, and reflect atmospheric deposition interaction with the forest canopy. This explained the higher enrichment measured in mosses for elements which concentration in deposition were influenced by the canopy, either due to leaching (Mn), direct uptake (Ni), or dry deposition dissolution (Pb, Cu, Cs).

Recognizing Dropstone Occurrences and their Potential for Insight into Glaciolacustrine Environments on Mars

NASA Astrophysics Data System (ADS)

Husch, J.; Cole, S. B.; Karunatillake, S.; Weindl, T.

2012-12-01

Glaciolacustrine environments, such as temporally persistent ice-covered lakes, have been proposed for several locations on Mars, including Gusev Crater[1], Greg Crater[2], and Gorgonum Chaos[3]. Morphologic features consistent with the Hesperian-age lava flows dammed by hundred-meter thick ice-rich deposits within Gusev Crater have also been described[4]. However, neither in-situ nor remote-sensing observations have provided unequivocal evidence for the existence of glaciolacustrine environments. In this context, targeted observations by in-situ missions (i.e., MER and MSL rovers) of coarse clasts embedded within, but compositionally distinct from, finer-grained layered deposits holds the potential for unambiguously distinguishing glaciolacustrine settings from volcaniclastic[5] alternatives. We use the single clast found at the Home Plate deposit in the Columbia Hills of Gusev Crater as a test case to develop a comprehensive strategy for identifying dropstones, also applicable with upcoming data from the Curiosity Rover within Gale Crater. A dropstone, consistent with glaciolacustrine origin, can be identified from 3 key indicators: (1) compositional distinctness from the surrounding sedimentary host; (2) smaller clast populations than would be expected for volcaniclastic bomb sags; (3) little, if any, disruption in bed continuity, particularly in the layers above a clast, relative to bomb sag occurrences. Although terrestrial dropstones commonly associate with fine-grained marine sediments and bomb sags with coarser sediments indicative of high-energy eruptive settings, the distinctions may fade at glaciolacustrine volcanic environments[6]. Spectrally coded MER Panoramic camera images show a common bluish tinge for the Home Plate clast and neighboring sediment layers, suggesting compositional similarity. Alternatively, the apparent similar mineralogy may be from surface alteration, while the interiors may be compositionally distinct; desert varnish analogs have been identified elsewhere on Mars[7]. Our preliminary assessment of the Home Plate clast, together with the proposed near-neutral pH alteration environments at the Comanche and related outcrops[8], provides tentative evidence for the existence of an ancient ice-covered lake within Gusev Crater, potentially reaching depths comparable to the ~100 m height of Columbia Hills. Greater depths are possible, given evidence for an eroded summit above the Tennessee Valley area[9]. Furthermore, these seemingly contradictory initial morphologic and geochemical results may be consistent with an environment where glaciolacustrine, volcaniclastic, and hydrothermal processes were active simultaneously. References [1] Grin, E. Icarus 130, 461-474 (1997) [2] Kargel, J. S. & Furfaro, R. A LPSC 43, 2629 (2012) [3] Howard, A. D. & Moore, J. M. Geophys. Res. Lett. 31, L01702 (2004) [4] Gregg, T. K. P. et al. Icarus 192, 348-360 (2007) [5] Lewis, K. W. et al. J. Geophys. Res. 113 E12S36 (2008) [6] Cousins, C. R. & Crawford, I. A. Astrobiology 11, 695-710 (2011) [7] Knoll, A. H. et al. J. Geophys. Res. 113, E06S16 (2008) [8] Ruff, S. W. LPSC 43, 2898 (2012) [9] Cole, S. B. et al. LPSC 43, 1134 (2012)

Do lichens have "memory" of their native nitrogen environment?

PubMed

Munzi, Silvana; Loppi, Stefano; Cruz, Cristina; Branquinho, Cristina

2011-02-01

This study aimed to deepen the knowledge about intraspecific mechanisms regulating nitrogen tolerance in lichens to wet nitrogen deposition. Thalli of the nitrophilous lichen Xanthoria parietina were collected from environments with different nitrogen availabilities and immersed in 80 mL of ammonium sulphate (NH₄)₂SO₄ solutions with distinct concentrations (0, 0.025, 0.05 and 0.25 M) for 5 h per day during 3 days in a week. After each soaking event, lichens were air dried. After each treatment, maximal PSII efficiency, localization of ammonium ions, concentrations of K+ and Mg²+ and thalli buffer capacity were determined. Our results show that lichens are marked by their native nitrogen environment, since there were important differences between the physiological responses of X. parietina thalli previously grown in an area with high nitrogen deposition (nitrogen emissions of ca. 13,000 t/year) and those previously grown in an unpolluted area (nitrogen emissions of ca. 500 t/year). Greater N availability seems to enable X. parietina to cope better with the effects of nitrogen pollution.

Geochemistry of placer gold, Koyukuk-Chandalar mining district, Alaska

USGS Publications Warehouse

Mosier, E.L.; Cathrall, J.B.; Antweiler, J.C.; Tripp, R.B.

1989-01-01

The Koyukuk-Chandalar mining district of the Brooks Range mineral belt in north-central Alaska contains numerous placer gold deposits but few known lode gold sources. Gold grains, collected from 46 placer localities and 6 lode gold sites in the district, were analyzed for Ag and 37 trace elements utilizing direct current-arc optical emission spectroscopy. When possible, several measurements were made on each sample and averaged. Gold content was calculated by the summation of the 38 elements determined and subtracting from 100. The objectives of our study were to characterize the deposits by defining the type and number of distinct geochemical characteristics for the Au, to determine relationships of Au in placer deposits to possible lode sources (placer and lode), to identify possible primary sources of placer gold, and to study processes of placer formation. Interpretation of results emphasize that the Au grains are almost invariably ternary (Au-Ag-Cu) alloys. The average Cu content is 0.040% and the average Ag content and fineness [(Au/Au+Ag)??1,000] are 10.5% and 893 parts per thousand, respectively, for the 46 placer localities. Six geochemically distinct types of placer gold can be identified in the Koyukuk-Chandalar mining district based on Ag and Cu values. One type with an average Ag content of 21.2%, an average Cu content of 0.007%, and 786 average fineness is found only in the eastern part of the district. Placer gold grains that have an average Ag content of 6.0%, an average Cu content of 0.276%, and 940 average fineness were found in the western part of the district. Four intermediate types generally occur in order across the district. Variations in the chemistry of the placer gold can be related to variable depositional environments at the primary gold sources. Placer gold geochemistry is important in determining the origin and depositional environment of the primary Au sources and could add to the knowledge of the thermal history of the southcentral Brooks Range. ?? 1989.

Endochondral bone formation in embryonic mouse pre-metatarsals

NASA Technical Reports Server (NTRS)

Klement, B. J.; Spooner, B. S.

1992-01-01

Long term exposure to a reduced gravitational environment has a deleterious effect on bone. The developmental events which occur prior to initial bone deposition will provide insight into the regulation of mature bone physiology. We have characterized a system in which the events preceding bone formation take place in an isolated in vitro organ culture environment. We show that cultured pre-metatarsal tissue parallels development of pre-metatarsal tissue in the embryo. Both undergo mesenchyme differentiation and morphogenesis to form a cartilage rod, which resembles the future bone, followed by terminal chondrocyte differentiation in a definite morphogenetic pattern. These sequential steps occur prior to osteoblast maturation and bone matrix deposition in the developing organism. Alkaline phosphatase (ALP) activity is a distinctive enzymatic marker for mineralizing tissues. We have measured this activity throughout pre-metatarsal development and show (a) where in the tissue it is predominantly found, and (b) that this is indeed the mineralizing isoform of the enzyme.

Chemical composition, stratigraphy, and depositional environments of the Black River Group (Middle Ordovician), southwestern Ohio.

USGS Publications Warehouse

Stith, David A.

1981-01-01

The chemical composition and stratigraphy of the Black River Group in southwestern Ohio were studied. Chemical analyses were done on two cores of the Black River from Adams and Brown Counties, Ohio. These studies show that substantial reserves of high-carbonate rock are present in the Black River at depths of less than 800 ft, in proximity to Cincinnati and the Ohio River. Stratigraphic studies show that the Black River Group has eight marker beds in its middle and upper portions and three distinct lithologic units in its lower portion; these marker beds and units are present throughout southwestern Ohio. The Black River Group correlates well with the High Bridge Group of Kentucky. Depositional environments of the Black River are similar to those of the High Bridge and to present-day tidal flats in the Bahamas.-Author

The dynamic bacterial communities of a melting High Arctic glacier snowpack

PubMed Central

Hell, Katherina; Edwards, Arwyn; Zarsky, Jakub; Podmirseg, Sabine M; Girdwood, Susan; Pachebat, Justin A; Insam, Heribert; Sattler, Birgit

2013-01-01

Snow environments can occupy over a third of land surface area, but little is known about the dynamics of snowpack bacteria. The effect of snow melt on bacterial community structure and diversity of surface environments of a Svalbard glacier was examined using analyses of 16S rRNA genes via T-RFLP, qPCR and 454 pyrosequencing. Distinct community structures were found in different habitat types, with changes over 1 week apparent, in particular for the dominant bacterial class present, Betaproteobacteria. The differences observed were consistent with influences from depositional mode (snowfall vs aeolian dusts), contrasting snow with dust-rich snow layers and near-surface ice. Contrary to that, slush as the decompositional product of snow harboured distinct lineages of bacteria, further implying post-depositional changes in community structure. Taxa affiliated to the betaproteobacterial genus Polaromonas were particularly dynamic, and evidence for the presence of betaproteobacterial ammonia-oxidizing bacteria was uncovered, inviting the prospect that the dynamic bacterial communities associated with snowpacks may be active in supraglacial nitrogen cycling and capable of rapid responses to changes induced by snowmelt. Furthermore the potential of supraglacial snowpack ecosystems to respond to transient yet spatially extensive melting episodes such as that observed across most of Greenland's ice sheet in 2012 merits further investigation. PMID:23552623

The dynamic bacterial communities of a melting High Arctic glacier snowpack.

PubMed

Hell, Katherina; Edwards, Arwyn; Zarsky, Jakub; Podmirseg, Sabine M; Girdwood, Susan; Pachebat, Justin A; Insam, Heribert; Sattler, Birgit

2013-09-01

Snow environments can occupy over a third of land surface area, but little is known about the dynamics of snowpack bacteria. The effect of snow melt on bacterial community structure and diversity of surface environments of a Svalbard glacier was examined using analyses of 16S rRNA genes via T-RFLP, qPCR and 454 pyrosequencing. Distinct community structures were found in different habitat types, with changes over 1 week apparent, in particular for the dominant bacterial class present, Betaproteobacteria. The differences observed were consistent with influences from depositional mode (snowfall vs aeolian dusts), contrasting snow with dust-rich snow layers and near-surface ice. Contrary to that, slush as the decompositional product of snow harboured distinct lineages of bacteria, further implying post-depositional changes in community structure. Taxa affiliated to the betaproteobacterial genus Polaromonas were particularly dynamic, and evidence for the presence of betaproteobacterial ammonia-oxidizing bacteria was uncovered, inviting the prospect that the dynamic bacterial communities associated with snowpacks may be active in supraglacial nitrogen cycling and capable of rapid responses to changes induced by snowmelt. Furthermore the potential of supraglacial snowpack ecosystems to respond to transient yet spatially extensive melting episodes such as that observed across most of Greenland's ice sheet in 2012 merits further investigation.

Sediment-hosted Pb-Zn Deposits: a global perspective

USGS Publications Warehouse

Leach, David L.; Sangster, Donald F.; Kelley, Karen D.; Large, R; Garven, G.; Allen, Craig R.

2005-01-01

Sediment-hosted Pb-Zn deposits contain the world's greatest lead and zinc resources and dominate world production of these metals. They are a chverse group of ore deposits hosted by a wide variety of carbonate and siliciclastic roch that have no obviolls genetic association with igneous activity. A nmge of ore-fortl1ing processes in a vmiety of geologic and tectonic environments created these deposits over at least two billion years of Earth history. The metals were precipitated by basinal brines in synsedimentary and early diagenetic to low-grade metamorphic environments. The deposits display a broad range of relationships to enclosing host rocks that includes stratiform, strata-bound, and discordant ores. These ores are divided into two broad subt)1Jes: Mississippi Valley-type (MVT) and sedimentmy exhalative (SEDEX), Despite the "exhalative" component inherent in the term "SEDEX," in this manusclipt, direct evidence of an exhalite in the ore or alteration component is not essential for a deposit to be classified as SEDEX. The presence of laminated sulfides parallel to bedding is assumed to be permissive evidence for exhalative ores. The chstinction between some SEDEX and MVT depOSits can be quite subjective because some SEDEX ores replaced carbonate, whereas some MVT depOSits formed in an early diagenetic environment and display laminated ore textures. Geologic and resource information are presented for 248 depositS that provide a framework to describe ,mel compare these deposits. Nine of tlle 10 largest sediment-hosted Pb-Zn deposits are SEDEX, Of the deposits that contain at least 2.5 million metric tons (Mt), there are 35 SEDEX (excluding Broken Hill-type) deposits and 15 MVT (excluding Iris-type) deposits. Despite the skewed distribution of the deposit size, the two deposits types have an excellent correlation between total tonnage and tonnage of contained metal (Pb + Zn), with a fairly consistent ratio of about lO/l, regardless of the size of the deposit or district. Zinc grades are approximately the same for both, whereas Pb and Ag grades are about 25 percent greater for SEDEX deposits. The largest difference between SEDEX and MVT deposits is their Cu content. Three times as many SEDEX deposits have reported Cu contents, and the median Cu value of SEDEX deposits is nearly double that of MVT deposits. Furthermore, grade-tonnage values for MVT deposits compared to a subset of SEDEX deposits hosted in carbonate rocks are virtually indistinguishable. The distribution of MVT deposits through geologic time shows that they are mainly a Phanerozoic phenomenon. The ages of SEDEX deposits are grouped into two major groups, one in the Proterozoic and another in the Phanerozoic, MVT deposits dominantly formed in platform carbonate sequences typically located within extensional zones inboard of orogenic belts, whereas SEDEX deposits formed in intracontinental or failed rifts, and rifted continental margins. The ages of MVT ores are generally tens of millions of years younger than their host rocks; however, a few are close <~5 m.y.) to the age of their host rocks. In the absence of direct dates for SEDEX deposits, their age of formation is generally constnuned by relationships to sedimentary or diagenetic features in the rocks. These studies suggest that deposition of SEDEX ores was coeval with sedimentation or early diagenesis, whereas some deposits formed at least 20 m.y. after sedimentation. Fluid inclusion, isotopic studies, and deposit modeling suggest that MVf and SEDEX deposits formed from basin brines with similar temperatures of mainly 90° to 200°C and lO to 30 wt percent NaCI equiv. Lead isotope compositions for MVT and SEDEX deposits show that Pb was mainly derived from a variety of crustal sources. Lead isotope compositions do not provide critelia that distinguish MVT from SEDEX subtypes. However, sulfur isotope compositions for sphalerite and galena show an apparent difference. SEDEX and MVf sulfur isotope compositions extend over a large range; however, most data for SEDEX ores have mainly positive isotopic compositions from 0 to 20 per mil. Isotopic values for MVf ores extend over a wider range and include more data with negative isotopic values. Given that there are relatively small differences between the metal character of MVT and SEDEX deposits and the fluids that deposited them, perhaps the most significant difference between these deposits is their depositional environment, which is determined by their respective tectonic settings. The contrasting tectonic setting also dictates the fundamental deposit attributes that generally set them apart, such as host-rock lithology, deposit morphology, and ore textures. Blief discussions are also presented on two controversial sets of deposits: Broken Hill-type deposits and a subset of deposits in the MVT group located in the Irish Midlands, considered by some authors to be a distinct ore type (Irish type). There are no Significant differences in grade tonnage values between MVT deposits and the subset that is described as Irish type. Most features of the Irish deposits are not distinct from the family of MVT deposits; however, the age of mineralization that is the same as or close to the age of the host rocks and the anomalously high fluid inclusion temperatures (up to 250°C) stand out as distinctly different from typical MVT ores. The dominance of bacteriogenic sulfur in the hish ores commonly ascribed as uniquely hish type is in fact no different from several MVT deposits or districts. A comparison of SEDEX and Broken Hill-type deposits shows that the latter deposits contain signiflcantly higher contents of Ag and Pb relative to SEDEX deposits. In terms of median values, Broken Hill-type deposits are almost three times more ellliched in Ag and one and a half times more enriched in Pb compared to other SEDEX deposits. Metamorphism is a charactelisoc feature but not a prerequisite for inclusion in the Broken Hill-type category, and IGlown Broken Hill-type examples appear to occur in Paleo- to Mesoproterozoic terranes. Broken Hill-type deposits remain an enigmatic grouping; however, there is sufficient evidence to support their inclusion as a separate category of SEDEX deposits.

Residence times of reef-island sediments constrained by post-mortem precipitates

NASA Astrophysics Data System (ADS)

Mann, Thomas; Wizemann, André; Kench, Paul; Jompa, Jamaluddin; Westphal, Hildegard

2017-04-01

The precipitation of carbonate cements is a rapid process in tropical marine environments. Distinct from calcification, the onset of cementation coincides with the termination of 14C uptake within carbonate-sediment forming organisms. Here we show that this relationship presents new opportunities for examining the temporal lag between organism death and deposition in carbonate systems - the prerequisite for reliable depositional chronologies. We dated skeletal constituents collected from discretely stratified reef-island deposits in Indonesia. In each of the strata, internally least cemented segments of the calcifying green alga Halimeda yield the youngest ages. Complementary mesocosm experiments on cementation rates reveal that post-mortem cement growth initiates within months after transport commences. Continuous pore-filling cementation promptly stabilizes the initially fragile Halimeda skeleton. Furthermore, abrasion experiments show that such cementation significantly increases the durability of segments during transport. Implications of these findings are profound in two respects; first, evaluating residence times of skeletal carbonate constituents based on abrasion features is far from being adequate. Second, the absence of cements within sedimentary Halimeda segments signals that post-mortem transport through the intertidal zone occurred quasi-instantaneously. Radiometric ages from such specimens should minimize the temporal lag between organism death and deposition thus making them reliable indicators of sedimentation in supratidal environments.

A synthesis of Martian aqueous mineralogy after 1 Mars year of observations from the Mars Reconnaissance Orbiter

USGS Publications Warehouse

Murchie, S.L.; Mustard, J.F.; Ehlmann, B.L.; Milliken, R.E.; Bishop, J.L.; McKeown, N.K.; Noe Dobrea, E.Z.; Seelos, F.P.; Buczkowski, D.L.; Wiseman, S.M.; Arvidson, R. E.; Wray, J.J.; Swayze, G.; Clark, R.N.; Des Marais, D.J.; McEwen, A.S.; Bibring, J.-P.

2009-01-01

Martian aqueous mineral deposits have been examined and characterized using data acquired during Mars Reconnaissance Orbiter's (MRO) primary science phase, including Compact Reconnaissance Imaging Spectrometer for Mars hyperspectral images covering the 0.4-3.9 ??m wavelength range, coordinated with higher-spatial resolution HiRISE and Context Imager images. MRO's new high-resolution measurements, combined with earlier data from Thermal Emission Spectrometer; Thermal Emission Imaging System; and Observatoire pour la Min??ralogie, L'Eau, les Glaces et l'Activiti?? on Mars Express, indicate that aqueous minerals are both diverse and widespread on the Martian surface. The aqueous minerals occur in 9-10 classes of deposits characterized by distinct mineral assemblages, morphologies, and geologic settings. Phyllosilicates occur in several settings: in compositionally layered blankets hundreds of meters thick, superposed on eroded Noachian terrains; in lower layers of intracrater depositional fans; in layers with potential chlorides in sediments on intercrater plains; and as thousands of deep exposures in craters and escarpments. Carbonate-bearing rocks form a thin unit surrounding the Isidis basin. Hydrated silica occurs with hydrated sulfates in thin stratified deposits surrounding Valles Marineris. Hydrated sulfates also occur together with crystalline ferric minerals in thick, layered deposits in Terra Meridiani and in Valles Marineris and together with kaolinite in deposits that partially infill some highland craters. In this paper we describe each of the classes of deposits, review hypotheses for their origins, identify new questions posed by existing measurements, and consider their implications for ancient habitable environments. On the basis of current data, two to five classes of Noachian-aged deposits containing phyllosilicates and carbonates may have formed in aqueous environments with pH and water activities suitable for life. Copyright 2009 by the American Geophysical Union.

Surficial geology of the sea floor in west-central Long Island Sound as shown by sidescan-sonar imagery

USGS Publications Warehouse

McMullen, K.Y.; Poppe, L.J.; DiGiacomo-Cohen, M. L.; Moser, M.S.; Christman, E.B.

2005-01-01

We used sidescan-sonar imagery detailing almost 300 km2 of the sea floor in west-central Long Island Sound in conjunction with bathymetry, sediment samples, bottom video, and seismic data to interpret the area's surficial geology. The distribution of sediments and sedimentary environments interpreted from these data sets represents the Quaternary geology, regional bathymetry, and effects of modern tidal- and wave-driven currents. Four distinct sedimentary environments consisting of 1) fine-grained deposition, 2) sorting and reworking, 3) coarse-grained bedload transport, and 4) erosion or nondeposition, were identified and mapped. Relatively low-energy environments prevail where deposition of clayey silts occurs in deeper water throughout the central part of the study area, and in the protected areas of the far northeastern corner. As low-energy environments transition to relatively high-energy environments, sorting and reworking of sand, silty sand, and sand-silt-clay takes place on the flanks of the shoals and over smaller bathymetric highs. Environments of coarse-grained bedload transport, distinguished by sandy sediments with current-derived bedforms, are located on an unnamed shoal in the northwestern part of the study area and directly to the south of this on Stratford Shoal. High-energy conditions are reflected by environments of erosion or nondeposition, which occur on bathymetric highs where gravel and gravelly sediments are present.

Sedimentology of the lower part of the Upper Triassic Chinle Formation and its relationship to uranium deposits, White Canyon area, southeastern Utah

USGS Publications Warehouse

Dubiel, Russell F.

1983-01-01

Closely spaced measured stratigraphic sections of the lower part of the Late Triassic Chinle Formation in the White Canyon area of southeastern Utah depict a fluvial-deltaic-lacustrine depositional sequence that hosts uranium deposits in basal fluvial sandstones. The basal Shinarump Member consists of predominantly trough-crossbedded, coarse-grained sandstone and minor gray, carbonaceous mudstone and is interpreted as a valley-fill sequence overlain by deposits of a braided stream system. The overlying Monitor Butte Member is composed of cyclic- and foreset-bedded siltstone, sandstone, and mudstone and is interpreted as a succession of low-energy fluvial, deltaic and orqanicrich, lacustrine-marsh sediments. The overlying Moss Back Member is composed of a laterally extensive, coarse- to medium-grained, conglomeratic sandstone and is interpreted as a braided-stream system that flowed north to northwest. The entire sequence was deposited in response to changes in local base level associated with a large lake that lay to the west. Isopachs of lithofacies indicate distinct lacustrine basins and a correspondence between these facies and modern structural synclines. Facies changes and coincidence of isopach thicks suggest that structural synclines were active in the Late Triassic and influenced the pattern of sediment distribution within the basins. Uranium mineralization appears to be related to certain low-energy depositional environments in that uranium is localized in fluvial sandstones that lie beneath organic-rich lacustrine-marsh mudstones and carbonaceous delta-front sediments. The reducing environment preserved in these facies may have played an important role in the localization of uranium.

Global analysis of gully composition using manual and automated exploration of CRISM imagery

NASA Astrophysics Data System (ADS)

Allender, Elyse; Stepinski, Tomasz F.

2018-03-01

Gully formations on Mars have been the focus of many morphological and mineralogical studies aimed at inferring the mechanisms of their formation and evolution. In this paper we have analyzed 354 globally distributed gully-bearing Full Resolution Targeted (FRT) Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) images. The primary goal of the analysis was to identify all spectrally distinct deposits in these images (if any) and to classify them into hydrated and non-hydrated categories using only CRISM summary parameters (Viviano-Beck et al., 2014). Such approach makes possible to analyze a very large set of all distinct deposits in 354 images. We found that 68% of these images lack any distinct deposits, 8% of images contain non-hydrated deposits which coincide with the gullies and 24% of images contain hydrated deposits which coincide with the gullies. These results are compared with the recent analysis of 110 CRISM images by Nuñez et al. (2016) who also found that most gullies coincide with indistinct deposits, but, contrary to our findings, they found a predominance of non-hydrated minerals among distinct deposits. We attribute this discrepancy in part to their smaller and geographically biased sample of images, and in part to differing protocols of categorizing images. The discrepancy between the two surveys is further increased if we count all deposits in FRT gully-bearing images, not just deposits directly coinciding with the gullies, obtaining 44% indistinct, 15% non-hydrated, and 41% hydrated images. The secondary goal of this study was to perform the same image survey using a recently developed automated method in order to assess its accuracy and thus its feasibility for performing future surveys. We found the overall accuracy of the auto-mapper to be 76.2% but its accuracy for discovering distinct deposits, and in particular, distinct hydrated deposits was lower. We attributed the deficiencies of the auto-mapper primarily to its sensitivity to presence of noise in images and especially to presence of speckle noise. It is however worth noting that qualitatively both manual and automatic surveys arrived at the same overall conclusion.

Controls of bedrock geochemistry on soil and plant nutrients in Southeastern Utah

USGS Publications Warehouse

Neff, J.C.; Reynolds, R.; Sanford, R.L.; Fernandez, D.; Lamothe, P.

2006-01-01

The cold deserts of the Colorado Plateau contain numerous geologically and geochemically distinct sedimentary bedrock types. In the area near Canyonlands National Park in Southeastern Utah, geochemical variation in geologic substrates is related to the depositional environment with higher concentrations of Fe, Al, P, K, and Mg in sediments deposited in alluvial or marine environments and lower concentrations in bedrock derived from eolian sand dunes. Availability of soil nutrients to vegetation is also controlled by the formation of secondary minerals, particularly for P and Ca availability, which, in some geologic settings, appears closely related to variation of CaCO3 and Ca-phosphates in soils. However, the results of this study also indicate that P content is related to bedrock and soil Fe and Al content suggesting that the deposition history of the bedrock and the presence of P-bearing Fe and Al minerals, is important to contemporary P cycling in this region. The relation between bedrock type and exchangeable Mg and K is less clear-cut, despite large variation in bedrock concentrations of these elements. We examined soil nutrient concentrations and foliar nutrient concentration of grasses, shrubs, conifers, and forbs in four geochemically distinct field sites. All four of the functional plant groups had similar proportional responses to variation in soil nutrient availability despite large absolute differences in foliar nutrient concentrations and stoichiometry across species. Foliar P concentration (normalized to N) in particular showed relatively small variation across different geochemical settings despite large variation in soil P availability in these study sites. The limited foliar variation in bedrock-derived nutrients suggests that the dominant plant species in this dryland setting have a remarkably strong capacity to maintain foliar chemistry ratios despite large underlying differences in soil nutrient availability. ?? 2006 Springer Science+Business Media, Inc.

Exploring Mars for Evidence of Habitable Environments and Life

NASA Technical Reports Server (NTRS)

DesMarais, David J.

2014-01-01

The climate of Mars has been more similar to that of Earth than has the climate of any other planet in our Solar System. But Mars still provides a valuable alternative example of how planetary processes and environments can affect the potential presence of life elsewhere. For example, although Mars also differentiated very early into a core, mantle and crust, it then evolved mostly if not completely without plate tectonics and has lost most of its early atmosphere. The Martian crust has been more stable than that of Earth, thus it has probably preserved a more complete record of its earliest history. Orbital observations determined that near-surface water was once pervasive. Orbiters have identified the following diverse aqueous sedimentary deposits: layered phyllosilicates, phyllosilicates in intracrater fans, plains sediments potentially harboring evaporitic minerals, deep phyllosilicates, carbonate-bearing deposits, intracrater clay-sulfate deposits, Meridiani-type layered deposits, valles-type layered deposits, hydrated silica-bearing deposits, and gypsum plains. These features, together with evidence of more vigorous past geologic activity, indicate that early climates were wetter and perhaps also somewhat warmer. The denser atmosphere that was required for liquid water to be stable on the surface also provided more substantial protection from radiation. Whereas ancient climates might have favored habitable environments at least in some localities, clearly much of the Martian surface for most of its history has been markedly less favorable for life. The combination of dry conditions, oxidizing surface environments and typically low rates of sedimentation are not conducive to the preservation of evidence of ancient environments and any biota. Thus a strategy is required whereby candidate sites are first identified and then characterized for their potential to preserve evidence of past habitable environments. Rovers are then sent to explore the most promising candidates. The Mars Exploration Rover (MER) Opportunity revealed that water once flowed to the surface across the vast Meridiani plains, creating saline lakes whose waters were roiled by ancient winds that also sculptured their salt deposits into sand dunes. Opportunity then drove more than 30 km to explore even older deposits on a crater rim. MER Spirit found evidence that thermal waters (heated by volcanism or by impacts?) altered rocks to create sulfate salts, and siliceous sinters. These discoveries indicate that an early hydrological cycle apparently sustained precipitation, streams and lakes. Liquid water participated in rock weathering reactions, such as iron and sulfur oxidation, that created distinctive weathering regimes. Volcanism, impacts, groundwater and ice interacted at least locally. Redox chemical energy from volcanism, hydrothermal activity and weathering of crustal materials would have been available for any life. Thus conditions might have supported life in the past, at least locally. The main objective of the Mars Science Laboratory (MSL) Curiosity rover is to determine the extent to which Gale crater hosted environments capable of supporting microbial life. The rover has already found stream gravels as well as sediments that might have been deposited in an ancient lake. The rover is now traversing to Mt. Sharp, a 5 km-high mound that is located on the crater floor and that exhibits layered sedimentary rocks having diverse minerals (sulfates and clays) that apparently formed in the presence of liquid water. This rock sequence was deposited over an extended time period in diverse potentially habitable watery environments. Curiosity is poised to characterize a a well-preserved rock record of hundreds of millions of years of diverse environments and profound climate change.

Multimodal fluorescence microscopy of prion strain specific PrP deposits stained by thiophene-based amyloid ligands.

PubMed

Magnusson, Karin; Simon, Rozalyn; Sjölander, Daniel; Sigurdson, Christina J; Hammarström, Per; Nilsson, K Peter R

2014-01-01

The disease-associated prion protein (PrP) forms aggregates which vary in structural conformation yet share an identical primary sequence. These variations in PrP conformation are believed to manifest in prion strains exhibiting distinctly different periods of disease incubation as well as regionally specific aggregate deposition within the brain. The anionic luminescent conjugated polythiophene (LCP), polythiophene acetic acid (PTAA) has previously been used to distinguish PrP deposits associated with distinct mouse adapted strains via distinct fluorescence emission profiles from the dye. Here, we employed PTAA and 3 structurally related chemically defined luminescent conjugated oligothiophenes (LCOs) to stain brain tissue sections from mice inoculated with 2 distinct prion strains. Our results showed that in addition to emission spectra, excitation, and fluorescence lifetime imaging microscopy (FLIM) can fruitfully be assessed for optical distinction of PrP deposits associated with distinct prion strains. Our findings support the theory that alterations in LCP/LCO fluorescence are due to distinct conformational restriction of the thiophene backbone upon interaction with PrP aggregates associated with distinct prion strains. We foresee that LCP and LCO staining in combination with multimodal fluorescence microscopy might aid in detecting structural differences among discrete protein aggregates and in linking protein conformational features with disease phenotypes for a variety of neurodegenerative proteinopathies.

Multimodal fluorescence microscopy of prion strain specific PrP deposits stained by thiophene-based amyloid ligands

PubMed Central

Magnusson, Karin; Simon, Rozalyn; Sjölander, Daniel; Sigurdson, Christina J; Hammarström, Per; Nilsson, K Peter R

2014-01-01

The disease-associated prion protein (PrP) forms aggregates which vary in structural conformation yet share an identical primary sequence. These variations in PrP conformation are believed to manifest in prion strains exhibiting distinctly different periods of disease incubation as well as regionally specific aggregate deposition within the brain. The anionic luminescent conjugated polythiophene (LCP), polythiophene acetic acid (PTAA) has previously been used to distinguish PrP deposits associated with distinct mouse adapted strains via distinct fluorescence emission profiles from the dye. Here, we employed PTAA and 3 structurally related chemically defined luminescent conjugated oligothiophenes (LCOs) to stain brain tissue sections from mice inoculated with 2 distinct prion strains. Our results showed that in addition to emission spectra, excitation, and fluorescence lifetime imaging microscopy (FLIM) can fruitfully be assessed for optical distinction of PrP deposits associated with distinct prion strains. Our findings support the theory that alterations in LCP/LCO fluorescence are due to distinct conformational restriction of the thiophene backbone upon interaction with PrP aggregates associated with distinct prion strains. We foresee that LCP and LCO staining in combination with multimodal fluorescence microscopy might aid in detecting structural differences among discrete protein aggregates and in linking protein conformational features with disease phenotypes for a variety of neurodegenerative proteinopathies. PMID:25495506

Source versus depositional controls on sandstone composition in a foreland basin: The El Imperial Formation (Mid Carboniferous-Lower Permian), San Rafael basin, western Argentina

DOE Office of Scientific and Technical Information (OSTI.GOV)

Espejo, E.S.; Lopez-Gamundi, O.R.

1994-01-01

The El Imperial Formation (mid-Carboniferous-Lower Permian) constitutes a progradational sandstone-rich succession deposited in the San Rafael foreland basin of western Argentina. Four facies associations have been identified: a basal glacial marine association, a shallow marine association, a deltaic association, and an uppermost fluvial association. Sand-prone deposits in the deltaic association, a shallow marine association, a deltaic association, and an uppermost fluvial association. Sand-prone deposits in the deltaic association are represented by prodelta and delta-front shales and subordinate fine sandstones (Facies A), deltaic platform, wave-reworked channel mouth-bar sandstones (Facies B), and fluvial-dominated distributary channel sandstones (Facies C). Analysis of framework grainsmore » of sandstone samples from Facies B and C shows two distinct mineral assemblages or petrofacies. The quartzose petrofacies is characterized by high contents of quartz and low percentages of feldspar and lithic grains. The quartzolithic petrofacies shows an increase in labile components, in particular lithic fragments, and a concomitant decrease in quartz. The quartzolithic petrofacies shows a source signature. Average detrital modes of sandstones from this petrofacies are similar to those from overlying fluvial sandstones. All wave-reworked, channel mouth-bar sandstones (Facies B) correspond compositionally to the quartzose petrofacies, whereas detrital modes from the distributary-channel sandstones (Facies C) fall into the quartzolithic petrofacies. This correspondence between depositional environment and petrofacies suggests a strong depositional influence on composition (depositional signature). Abrasion (mechanical breakdown) by wave action in shallow marine environments accounts for the quartz-rich nature and paucity of labile grains in the quartzose petrofacies.« less

Diatom community and palaeoenvironmental properties of Karacaören diatomite deposits (Nevşehir, Central Anatolia, Turkey)

NASA Astrophysics Data System (ADS)

Yıldız, Ayşegül; Gürel, Ali; Dursun, Yusuf Gökhan

2017-10-01

The diatom community and palaeoenvironmental properties of volcano genetic diatomite deposits that outcrop in the Karacaören (Nevşehir) area are described. Two stratigraphic sections were measured in the study area. One of these sections was measured in Quaternary lake units (K1), and the other in lacustrine sediments of the late Miocene-Pliocene Ürgüp Formation's Bayramhacılı Member (K2). According to stratigraphic and chemical characteristics of the sections, two distinct paleogeographic domains were determined in the study area. One of these, the shallow lacustrine to fluvial area (Quaternary) which is represented by an alternating sequence of diatomite, silt/mud, and tuffite. The other was the deeper lacustrine stage (late Miocene) which is represented by diatomites with some interbedded mud facies, chert and volcanics. From the diatomite samples of these sections, twenty-five species of 10 different diatom genera were identified. When evaluated together, the ecological properties and the distribution of numerical values of the determined diatom genera and species, showed that the study area's diatomite was generally deposited in shallow, high temperature, nutrient-rich water, where nitrogen and phosphorus were abundant and which was an alkaline (pH > 7) freshwater lake environment. Over time the pH value of the environment decreased (pH < 7), and the environment became acidic.

Modern sedimentary environments on the Rhode Island inner shelf, off the eastern United States

USGS Publications Warehouse

Knebel, H.J.; Needell, S. W.; O'Hara, C. J.

1982-01-01

Analyses of side-scan sonar records along with previously published bathymetric, textural and subbottom data reveal the sedimentary environments on the inner Continental Shelf south of Narragansett Bay, Rhode Island. The bottom topography in this area is characterized by a broad central depression bordered by shallow, irregular sea floor on the north and east and by a discontinuous, curvilinear ridge on the south and west. Four distinct environments were identified: 1. (1) Pre-Mesozoic coastal rocks are exposed on the sea floor at isolated locations near the shore (waterdepths <32 m). These exposures have pronounced, irregular topographic relief and produce blotchy patterns on side-scan sonographs. 2. (2) Glacial moraine deposits form the discontinuous offshore ridge. These deposits have hummocky sea-floor relief, are covered by lag gravel and boudlers, and appear as predominantly black (strongly reflective) patterns on the side-scan records. 3. (3) Over most of the shallow, irregular bottom in the northeast, on the flanks of the morainal ridge, and atop bathymetric highs, the sea floor is characterized as a mosaic of light and dark patches and lineations. The dark (more reflective) zones are areas of coarse sands and megaripples (wavelengths = 0.8-1.2 m that either have no detectable relief or are slightly depressed relative to surrounding (light) areas of finer-grained sands. 4. (4) Smooth beds that produce nearly featureless patterns on the sonographs occupy the broad central bathymetric depression as well as smaller depressions north and east of Block Island. Within the broad depression, sonographs having practically no shading indicate a central zone of modern sandy silt, whereas records having moderate tonality define a peripheral belt of silty sand. The sedimentary environments that are outlined range from erosional or non-depositional (bedrock, glacial moraine) to depositional (featureless beds), and include areas that may reflect a combination of erosional and depositional processes (textural patchiness). The distribution and characteristics of the environments reveal the general post-glacial sedimentary history of this area and provide a guide to future utilization of the shelf surface. ?? 1982.

Preservation of Biological Information in Thermal Spring Deposits: Developing a Strategy for the Search for Fossil Life on Mars

NASA Astrophysics Data System (ADS)

Walter, M. R.; Des Marais, David J.

1993-01-01

Current interpretations of the early history of Mars suggest many similarities with the early Earth and therefore raise the possibility that the Archean and Proterozoic history of life on Earth could have a counterpart on Mars. Terrestrial experience suggests that, with techniques that can be employed remotely, ancient springs, including thermal springs, could well yield important information. By delivering water and various dissolved species to the sunlit surface of Mars, springs very likely created an environment suitable for life, which could have been difficult, if not impossible, to attain elsewhere. The chemical and temperature gradients associated with thermal springs sort organisms into sharply delineated, distinctive and different communities, and so diverse organisms are concentrated into relatively small areas in a predictable and informative fashion. A wide range of metabolic strategies are concentrated into small areas, thus furnishing a useful and representative sampling of the existing biota. Mineral-charged springwaters frequently deposit chemical precipitates of silica and/or carbonate which incorporate microorganisms and preserve them as fossils. The juxtaposition of stream valley headwaters with volcanoes and impact craters on Mars strongly implies that subsurface heating of groundwater created thermal springs. On Earth, thermal springs create distinctive geomorphic features and chemical signatures which can be detected by remote sensing. Spring deposits can be quite different chemically from adjacent rocks. Individual springs can be hundreds of meters wide, and complexes of springs occupy areas up to several kilometers wide. Benthic microbial mats and the resultant stromatolites occupy a large fraction of the available area. The relatively high densities of fossils and microbial mat fabrics within these deposits make them highly prospective in any search for morphological evidence of life, and there are examples of microbial fossils in spring deposits as old as 300 Myr.

Petrographic, fluid inclusion and isotopic study of the Dikulushi Cu-Ag deposit, Katanga (D.R.C.): implications for exploration

NASA Astrophysics Data System (ADS)

Haest, Maarten; Muchez, Philippe; Dewaele, Stijn; Boyce, Adrian J.; von Quadt, Albrecht; Schneider, Jens

2009-07-01

The Dikulushi Cu-Ag vein-type deposit is located on the Kundelungu Plateau, in the southeastern part of the Democratic Republic of Congo (D.R.C.). The Kundelungu Plateau is situated to the north of the Lufilian Arc that hosts the world-class stratiform Cu-Co deposits of the Central African Copperbelt. A combined petrographic, fluid inclusion and stable isotope study revealed that the mineralisation at Dikulushi developed during two spatially and temporally distinct mineralising episodes. An early Cu-Pb-Zn-Fe mineralisation took place during the Lufilian Orogeny in a zone of crosscutting EW- and NE-oriented faults and consists of a sequence of sulphides that precipitated from moderate-temperature, saline H2O-NaCl-CaCl2-rich fluids. These fluids interacted extensively with the country rocks. Sulphur was probably derived from thermochemical reduction of Neoproterozoic seawater sulphate. Undeformed, post-orogenic Cu-Ag mineralisation remobilised the upper part of the Cu-Pb-Zn-Fe mineralisation in an oxidising environment along reactivated and newly formed NE-oriented faults in the eastern part of the deposit. This mineralisation is dominated by massive Ag-rich chalcocite that precipitated from low-temperature H2O-NaCl-KCl fluids, generated by mixing of moderate- and low-saline fluids. The same evolution in mineralisation assemblages and types of mineralising fluids is observed in three other Cu deposits on the Kundelungu Plateau. Therefore, the recognition of two distinct types of (vein-type) mineralisation in the study area has a profound impact on the exploration in the Kundelungu Plateau region. The identification of a Cu-Ag type mineralisation at the surface could imply the presence of a Cu-Pb-Zn-Fe mineralisation at depth.

Preservation of biological information in thermal spring deposits: developing a strategy for the search for fossil life on Mars.

PubMed

Walter, M R; Des Marais, D J

1993-01-01

Current interpretations of the early history of Mars suggest many similarities with the early Earth and therefore raise the possibility that the Archean and Proterozoic history of life on Earth could have a counterpart on Mars. Terrestrial experience suggests that, with techniques that can be employed remotely, ancient springs, including thermal springs, could well yield important information. By delivering water and various dissolved species to the sunlit surface of Mars, springs very likely created an environment suitable for life, which could have been difficult, if not impossible, to attain elsewhere. The chemical and temperature gradients associated with thermal springs sort organisms into sharply delineated, distinctive and different communities, and so diverse organisms are concentrated into relatively small areas in a predictable and informative fashion. A wide range of metabolic strategies are concentrated into small areas, thus furnishing a useful and representative sampling of the existing biota. Mineral-charged springwaters frequently deposit chemical precipitates of silica and/or carbonate which incorporate microorganisms and preserve them as fossils. The juxtaposition of stream valley headwaters with volcanoes and impact craters on Mars strongly implies that subsurface heating of groundwater created thermal springs. On Earth, thermal springs create distinctive geomorphic features and chemical signatures which can be detected by remote sensing. Spring deposits can be quite different chemically from adjacent rocks. Individual springs can be hundreds of meters wide, and complexes of springs occupy areas up to several kilometers wide. Benthic microbial mats and the resultant stromatolites occupy a large fraction of the available area. The relatively high densities of fossils and microbial mat fabrics within these deposits make them highly prospective in any search for morphological evidence of life, and there are examples of microbial fossils in spring deposits as old as 300 Myr.

Effect of silver nanoparticle coatings on mycobacterial biofilm attachment and growth: Implications for ceramic water filters

NASA Astrophysics Data System (ADS)

Larimer, Curtis James

Silver is a natural, broad-spectrum antibacterial metal and its toxicity can be enhanced when surface area is maximized. As a result, silver nanoparticles (AgNP) have been investigated for use in novel water treatment technologies. The hypothesis of this work is that deposited AgNPs can enhance water treatment technologies by inhibiting growth of planktonic bacteria and biofilms. This was investigated by evaluating the antibacterial efficacy of AgNPs both in solution and as deposited on surfaces. AgNPs were found to be toxic to three species of environmental mycobacteria, M. smegmatis, M. avium, and M. marinum and the level of susceptibility varied widely, probably owing to the varying levels of silver that each species is exposed to in its natural environment. When cultured in a AgNP enriched environment M. smegmatis developed resistance to the toxic effects of both the nanoparticles and silver ions. The resistant mutant was as viable as the unmodified strain and was also resistant to antibiotic isoniazid. However, the strain was more susceptible to other toxic metal ions from ZnSO4 and CuSO4. AgNPs were deposited on silicon wafer substrates by vertical colloidal deposition (VCD). Manipulating deposition speed and also concentration of AgNPs in the depositing liquid led to a range of AgNP coatings with distinctive deposition lines perpendicular to the motion of the meniscus. Experimental results for areal coverage, which was measured from SEM images of AgNP coatings, were compared to Diao's theory of VCD but did not show agreement due to a stick-slip mechanism that is not accounted for by the theory. Durability of AgNP coatings is critical for antibacterial efficacy and to mitigate the risks of exposing the environment to nanomaterials and it was measured by exposing AgNP coatings to liquid flow in a flow cell. Durability was improved by modifying processing to include a heat treatment after deposition. Finally, the antibiofilm efficacy of deposited AgNPs was demonstrated by culturing M. smegmatis on porous membrane filters and Si substrates that were coated with AgNP. In both cases AgNP inhibited biofilm growth with an effect that was concentration or areal coverage dependent.

Textural characteristics and sedimentary environment of sediment at eroded and deposited regions in the severely eroded coastline of Batu Pahat, Malaysia.

PubMed

Wan Mohtar, Wan Hanna Melini; Nawang, Siti Aminah Bassa; Abdul Maulud, Khairul Nizam; Benson, Yannie Anak; Azhary, Wan Ahmad Hafiz Wan Mohamed

2017-11-15

This study investigates the textural characteristics of sediments collected at eroded and deposited areas of highly severed eroded coastline of Batu Pahat, Malaysia. Samples were taken from systematically selected 23 locations along the 67km stretch of coastline and are extended to the fluvial sediments of the main river of Batu Pahat. Grain size distribution analysis was conducted to identify its textural characteristics and associated sedimentary transport behaviours. Sediments obtained along the coastline were fine-grained material with averaged mean size of 7.25 ϕ, poorly sorted, positively skewed and has wide distributions. Samples from eroded and deposition regions displayed no distinctive characteristics and exhibited similar profiles. The high energy condition transported the sediments as suspension, mostly as pelagic and the sediments were deposited as shallow marine and agitated deposits. The fluvial sediments of up to 3km into the river have particularly similar profile of textural characteristics with the neighbouring marine sediments from the river mouth. Profiles were similar with marine sediments about 3km opposite the main current and can go up to 10km along the current of Malacca Straits. Copyright © 2017 Elsevier B.V. All rights reserved.

Eustatic and far-field tectonic control on the development of an intra-platform carbonate-shoal complex: upper tongue of the Tanglewood Member, Upper Ordovician Lexington Limestone, central Kentucky, U.S.A.

NASA Astrophysics Data System (ADS)

Koirala, Dibya Raj; Ettensohn, Frank R.; Clepper, Marta L.

2016-11-01

The Lexington or Trenton Limestone is an Upper Ordovician (Chatfieldian-Edenian; upper Sandbian-lower Katian), temperate-water unit, averaging about 60-m thick, that was deposited in relatively shallow waters across the Lexington Platform in east-central United States during the Taconian Orogeny. Lexington/Trenton shallow-water deposition ended across most of the platform in late Chatfieldian time and from that point deepened upward into the more shale-rich Clays Ferry, Point Pleasant and Kope formations due to apparent sea-level rise. In central Kentucky, however, deposition of the Lexington Limestone continued into early Edenian time and includes up to 50 m of additional coarse calcarenites and calcirudites at the top, which form the Tanglewood buildup and reflect locally regressive conditions, apparently related to local structural uplift. Consequently, in central Kentucky, the Lexington is more than 100-m thick, and Lexington deposition on the buildup continued into early Edenian time as an intra-platform shoal complex that tongues out into deeper-water units in all directions. In an attempt to understand how this shoal complex developed, we examined the last major body of coarse skeletal sands in the central Kentucky Lexington Limestone, the upper tongue of the Tanglewood Member, a 12-m-thick succession of fossiliferous calcarenite and calcirudite that occurs across an area of 5200 km2 near the center of the Lexington Platform. Although relatively homogeneous, the upper Tanglewood is divisible into five, small-scale, fining-upward, sequence-like cycles, which contain prominent, widespread deformed horizons. Facies analysis indicates that four lithofacies, which reflect distinct depositional environments, comprise the sequences across the shoal complex. Lithofacies were correlated across the shoal complex by integrating cyclicity and widespread deformed horizons in order to delineate the locations of major depositional environments. Facies analysis shows that the thickest and coarsest parts of each sequence, and the shallowest depositional environments, coincide with basement fault blocks, which are known to have experienced uplift during earlier Lexington Limestone deposition. The occurrence of thick, coarse facies on the same blocks suggests that the blocks continued to experience uplift into shallow water, where tides and waves redistributed sediments during upper Tanglewood deposition. Although eustasy apparently controlled cyclicity, Taconian far-field forces generated by orogeny in the east seem to have influenced facies distribution in each cycle through reactivation of basement fault zones as synsedimentary growth faults. The example of the upper Tanglewood Member shows that tectonic far-field forces can exert important influences on the development of carbonate depositional environments, even in distal intracratonic settings like the Lexington Platform.

Sensors based on visible collective resonances of plasmonic lattices

NASA Astrophysics Data System (ADS)

Sadeghi, Seyed M.; Wing, Waylin J.; Campbell, Quinn

2016-09-01

We show arrays of large gold nanodisks on glass substrates can support strong optical features with narrow spectral widths associated with their collective plasmonic-lattice modes. Our results show that these modes can offer significant sensitivity to the refractive index of the environment, far more than those of individual nanodisks. We show the visible collective modes supported by such arrays can distinctively detect a monolayer of biotin with high resolution. We use donor (CdSe/ZnS) and acceptor (CuInS/ZnS) quantum dots to investigate the field properties of these arrays after deposition of a thick layer of a silicon. We demonstrate a distinct increase of emission of CuInS/ZnS quantum dots, indicating the possibility of enhancement of energy transfer between these two types of quantum dots.

Paleolakes and life on early Mars

NASA Technical Reports Server (NTRS)

Meyer, M. A.; Wharton, Robert A., Jr.; Mckay, C. P.

1991-01-01

Two distinct directions have begun to elucidate key parameters in the search for extinct life on Mars. Carbonate sediments, deposited about 10,000 years ago in association with biological activity, have been sampled from the paleolake beds of Lake Vanda and Meirs in the McMurdo Dry Valleys in Antarctica. These samples are being analyzed for simple biological signatures that remain in cold and dry paleolake sediments, namely microfossils, percent carbonate, and total organic carbon. Our second initiative is the study of Colour Lake, in the Canadian Arctic, that periodically maintains a perennial ice cover. Physical measurements started this year will be used to determine one end point for ice covered lake environments and will be compared to continuous measurements from Antarctic lakes started in November 1985. Interestingly, Colour Lake also supports benthic mat communities, but the low pH precludes carbonate deposition. This research will broaden our knowledge base for what conditions are necessary for ice covered lake formation and what biological signatures will remain in paleolake deposits.

Constraining the sedimentology and stratigraphy of submarine intraslope lobe deposits using exhumed examples from the Karoo Basin, South Africa

NASA Astrophysics Data System (ADS)

Spychala, Y. T.; Hodgson, D. M.; Flint, S. S.; Mountney, N. P.

2015-06-01

Intraslope lobe deposits provide a process record of the infill of accommodation on submarine slopes and their recognition enables the accurate reconstruction of the stratigraphic evolution of submarine slope systems. Extensive exposures of discrete sand-prone packages in Units D/E and E, Fort Brown Formation, Karoo Basin, South Africa, permit analysis of the sedimentology and stacking patterns of three intraslope lobe complexes and their palaeogeographic reconstruction via bed-scale analysis and physical correlation of key stratal surfaces. The sand-prone packages comprise tabular, aggradationally to slightly compensationally stacked lobe deposits with constituent facies associations that can be attributed to lobe axis, lobe off-axis, lobe-fringe and distal lobe-fringe environments. Locally, intraslope lobe deposits are incised by low aspect ratio channels that mark basinward progradation of the deepwater system. The origin of accommodation on the slope for lobe deposition is interpreted to be due to differential compaction or healing of scars from mass wasting processes. The stacking patterns and sedimentary facies arrangement identified in this study are distinct from those of more commonly recognized basin-floor lobe deposits, thereby enabling the establishment of recognition criteria for intraslope lobe deposits in other less well exposed and studied fine-grained systems. Compared to basin floor lobes, intraslope lobes are smaller in volume, influenced by higher degrees of confinement, and tend to show aggradational stacking patterns.

Tracking Reactive Nitrogen Sources, Chemistry and Deposition in Urban Environments Using Stable Isotopes

NASA Astrophysics Data System (ADS)

Hastings, M. G.; Clark, S. C.; Chai, J.; Joyce, E.; Miller, D. J.; Schiebel, H.; Walters, W.

2017-12-01

Reactive nitrogen (Nr) includes compounds such as nitrogen oxides (NOx, HONO), ammonia (NH3), nitrate (NO3-), ammonium (NH4+), and organic nitrates. These compounds serve major roles in controlling the composition of our atmosphere, and have a direct impact on ecosystem health and water quality. Our research is focused on using stable isotopes of Nr to investigate variations in sources, chemistry, atmospheric transport, and deposition. Our aim is to fingerprint distinct emission sources - such as vehicles, power plants, aircraft, agriculature, wildfires, and lightning - and track their influence in the environment. We have recently characterized vehicle emission plumes, emissions from agricultural soils under different management practices, and (in the near future) wildfire plumes in the western U.S. Our approach targets characterizing the isotopic composition of NOx, HONO, and NH3 at both the emissions source and the plume scale. In contrast to large ranges found for individual tailpipe emissions of NOx, on-road plumes in the U.S. have a mean δ15N of -4.7 ± 1.7‰. The plume scale approach integrates across the typical U.S. fleet giving a representative value that can be used for tracking the impact of this emission source in the environment. NH3 also tends towards a narrow isotopic range when considered at the roadside scale compared to individual vehicles. In agricultural settings, the isotopes of NOx and HONO released from soils under different fertilizer practices is typically very negative in δ15N (-40 to -10‰) and appears to vary most with soil N properties rather than meteorology. Our work is now extending to discern sources influencing Nr deposition in an urban area at the head of New England's largest estuary. National monitoring of N deposition shows decreases in NO3- (but not NH4+) deposition over the last two decades, following better controls on NOx emissions. Wet deposition collected in an urban area exhibits N concentrations that are often 3-5 times higher than that found in regional monitoring networks. An event-based, year-round record of the isotopic composition of NO3- and NH4+ in wet deposition is currently underway with the aim of constraining local versus transported emissions sources and understanding the implications of very concentrated deposition events on a major urban watershed.

Textural Maturity Analysis and Sedimentary Environment Discrimination Based on Grain Shape Data

NASA Astrophysics Data System (ADS)

Tunwal, M.; Mulchrone, K. F.; Meere, P. A.

2017-12-01

Morphological analysis of clastic sedimentary grains is an important source of information regarding the processes involved in their formation, transportation and deposition. However, a standardised approach for quantitative grain shape analysis is generally lacking. In this contribution we report on a study where fully automated image analysis techniques were applied to loose sediment samples collected from glacial, aeolian, beach and fluvial environments. A range of shape parameters are evaluated for their usefulness in textural characterisation of populations of grains. The utility of grain shape data in ranking textural maturity of samples within a given sedimentary environment is evaluated. Furthermore, discrimination of sedimentary environment on the basis of grain shape information is explored. The data gathered demonstrates a clear progression in textural maturity in terms of roundness, angularity, irregularity, fractal dimension, convexity, solidity and rectangularity. Textural maturity can be readily categorised using automated grain shape parameter analysis. However, absolute discrimination between different depositional environments on the basis of shape parameters alone is less certain. For example, the aeolian environment is quite distinct whereas fluvial, glacial and beach samples are inherently variable and tend to overlap each other in terms of textural maturity. This is most likely due to a collection of similar processes and sources operating within these environments. This study strongly demonstrates the merit of quantitative population-based shape parameter analysis of texture and indicates that it can play a key role in characterising both loose and consolidated sediments. This project is funded by the Irish Petroleum Infrastructure Programme (www.pip.ie)

The fate of Mercury in Arctic regions: New understanding of atmospheric chemical processes and mercury stability in snow.

NASA Astrophysics Data System (ADS)

Steffen, A.; Ferrari, C.; Dommergue, A.; Scherz, T.; Lawson, G.; Leiatch, R.

2006-12-01

Mercury is a known toxic pollutant in the Arctic environment. Atmospheric mercury depletion events (AMDEs) have been studied in the Arctic since 1995. While advances in understanding this newly discovered cycling of mercury in the atmosphere have been made, much of the chemistry and the impact of this annually reoccurring event to the Arctic ecosystem are not well understood. Four years of continuous measurements at Alert, Canada of so-called reactive gaseous mercury (RGM) and mercury associated to particles (PHg) coupled with ongoing snow sampling have produced new information on the atmospheric chemistry and deposition of these mercury species to the Arctic. A distinct pattern during the springtime period in the distribution of these atmospheric mercury species has emerged. This pattern is characterized by the predominance of PHg concentration at the onset of the AMDEs. During the latter part of the AMDE season, there is an obvious swicth in the speciation of mercury to RGM as the main component during AMDEs. This swicth from PHg to RGM is clearly linked to a significant increase of mercury in the snow. In addition, concentrations of PHg are clearly linked with particles in the air that are primarily associated with Arctic haze. Recently, similar results have also been observed in Ny-Alesund (Svalbard). Further observations indicate that once deposited, the deposited mercury appears to evolve chemically in the snow. This change in mercury may impact the transfer of mercury to the environment during snow melt. These first time observed links between atmospheric conditions and subsequent deposition of mercury may help to ascertain the conditions throughout the Arctic as to when significant deposition of mercury will occur. It is proposed that should the concentration of atmospheric particles increase in the Arctic due to long range transport from emission sources, an increase in the deposition of mercury to this environment will increase during the springtime period. Additionally, information from these data demonstrates that the primary product of the oxidation of gaseous elemental mercury (GEM) is RGM which will associate to the particles and exist as PHg when these particles are available in the atmosphere. The oxidation of GEM is, therefore, a result of homogeneous chemistry. Results from this ongoing study and the impacts of this pollutant to the Arctic environment will be presented.

To what extent can intracrater layered deposits that lack clear sedimentary textures be used to infer depositional environments?

NASA Astrophysics Data System (ADS)

Cadieux, Sarah B.; Kah, Linda C.

2015-03-01

Craters within Arabia Terra, Mars, contain hundreds of meters of layered strata showing systematic alternation between slope- and cliff-forming units, suggesting either rhythmic deposition of distinct lithologies or similar lithologies that experienced differential cementation. On Earth, rhythmically deposited strata can be examined in terms of stratal packaging, wherein the interplay of tectonics, sediment deposition, and base level (i.e., the position above which sediment accumulation is expected to be temporary) result in changes in the amount of space available for sediment accumulation. These predictable patterns of sediment deposition can be used to infer changes in basin accommodation regardless of the mechanism of deposition (e.g. fluvial, lacustrine, or aeolian). Here, we analyze sedimentary deposits from three craters (Becquerel Crater, Danielson Crater, Crater A) in Arabia Terra. Each crater contains layered deposits that are clearly observed in orbital images. Although orbital images are insufficient to specifically determine the origin of sedimentary deposits, depositional couplets can be interpreted in terms of potential accommodation space available for deposition, and changes in the distribution of couplet thickness through stratigraphy can be interpreted in terms of changing base level and the production of new accommodation space. Differences in stratal packaging in these three craters suggest varying relationships between sedimentary influx, sedimentary base level, and concomitant changes in accommodation space. Previous groundwater upwelling models hypothesize that layered sedimentary deposits were deposited under warm climate conditions of early Mars. Here, we use observed stacking patterns to propose a model for deposition under cold climate conditions, wherein episodic melting of ground ice could raise local base level, stabilize sediment deposition, and result in differential cementation of accumulated strata. Such analysis demonstrates that a first-order understanding of sedimentary deposition and accumulation-despite a lack of textural information that inhibits interpretation of depositional mechanism-can provide insight into potentially changeable depositional conditions of early Mars.

Letter to the editor: Critical assessments of the current state of scientific knowledge, terminology, and research needs concerning the ecological effects of elevated atmospheric nitrogen deposition in China

NASA Astrophysics Data System (ADS)

Pan, Yuepeng; Liu, Yongwen; Wentworth, Gregory R.; Zhang, Lin; Zhao, Yuanhong; Li, Yi; Liu, Xuejun; Du, Enzai; Fang, Yunting; Xiao, Hongwei; Ma, Hongyuan; Wang, Yuesi

2017-03-01

In a publication in Atmospheric Environment (http://dx.doi.org/10.1016/j.atmosenv.2015.10.081), Gu et al. (2015) estimated that "the total nitrogen (N) deposition in 2010 was 2.32 g N m-2 yr-1" in China. This value is comparable with previous estimations based on a synthesized dataset of wet/bulk inorganic N deposition observations, which underestimates the total N deposition since their algorithm (equations (2) and (3) in their paper) does not account for dry deposition of NH3, HNO3, NOx and wet/dry deposition of HONO and organic nitrogen (e.g. amines, amides, PAN). Indeed, Gu et al. (2015) mixed the terminology of wet/bulk deposition and total deposition. Another flawed assumption by Gu et al. (2015) is that all inorganic N in precipitation estimated by their algorithm originates from fertilizer and coal combustion. This is incorrect and almost certainly causes biases in the spatial and temporal distribution of estimated wet/bulk inorganic N deposition (Fig. 5 in their paper), further considering the fact that they neglected important N sources like livestock and they did not consider the nonlinearity between various sources and deposition. Besides the input data on N deposition, the model validation (Sect. 2.3.2) described in their paper also requires clarification because the detailed validation information about the time series of observational dataset versus modeling results was not given. As a result of these combined uncertainties in their estimation of N deposition and the lack of detail for model-measurement comparison, their estimates of the impacts of N deposition on carbon storage in Chinese forests may need further improvement. We suggest the clarification of the terminology regarding N deposition, especially for wet deposition, bulk deposition, gaseous and particulate dry deposition or total deposition since the accurate distinction between these terms is crucial to investigating and estimating the effects of N deposition on ecosystems.

Extended Kd distributions for freshwater environment.

PubMed

Boyer, Patrick; Wells, Claire; Howard, Brenda

2018-06-18

Many of the freshwater K d values required for quantifying radionuclide transfer in the environment (e.g. ERICA Tool, Symbiose modelling platform) are either poorly reported in the literature or not available. To partially address this deficiency, Working Group 4 of the IAEA program MODARIA (2012-2015) has completed an update of the freshwater K d databases and K d distributions given in TRS 472 (IAEA, 2010). Over 2300 new values for 27 new elements were added to the dataset and 270 new K d values were added for the 25 elements already included in TRS 472 (IAEA, 2010). For 49 chemical elements, the K d values have been classified according to three solid-liquid exchange conditions (adsorption, desorption and field) as was previously carried out in TRS 472. Additionally, the K d values were classified into two environmental components (suspended and deposited sediments). Each combination (radionuclide x component x condition) was associated with log-normal distributions when there was at least ten K d values in the dataset and to a geometric mean when there was less than ten values. The enhanced K d dataset shows that K d values for suspended sediments are significantly higher than for deposited sediments and that the variability of K d distributions are higher for deposited than for suspended sediments. For suspended sediments in field conditions, the variability of K d distributions can be significantly reduced as a function of the suspended load that explains more than 50% of the variability of the K d datasets of U, Si, Mo, Pb, S, Se, Cd, Ca, B, K, Ra and Po. The distinction between adsorption and desorption conditions is justified for deterministic calculations because the geometric means are systematically greater in desorption conditions. Conversely, this distinction is less relevant for probabilistic calculations due to systematic overlapping between the K d distributions of these two conditions. Copyright © 2018. Published by Elsevier Ltd.

Age and Construction of Little Ambergris Cay Bedrock Rim, Southeastern Caicos Platform, British West Indies

NASA Astrophysics Data System (ADS)

Orzechowski, E. A.; Strauss, J. V.; Knoll, A. H.; Fischer, W. W.; Cantine, M.; Metcalfe, K.; Quinn, D. P.; Stein, N.; Gomes, M. L.; Grotzinger, H. M.; Lingappa, U.; O'Reilly, S. S.; Riedman, L. A.; Trower, L.; Grotzinger, J. P.

2016-12-01

The Caicos Platform's interior-platform ooid shoals and patch reef environments are unique modern examples of grain-rich carbonate settings. In July 2016, the Agouron Institute's Advanced Geobiology field course conducted a detailed study of Little Ambergris Cay, in the southeastern sector of the platform. The cay is fringed by a topographically high rim formed of amalgamated ridges of partially lithified fossiliferous grainstone and rudstone (i.e. beachrock conglomerate), that protects an interior basin dominated by microbial mats and mangroves. Tidal channels exchanging open platform waters with the interior basin breach the rim locally. We sampled and mapped the rim (using differential GPS) in order to examine its age, sedimentological characteristics, and faunal composition. Strata up to 2 meters above the present-day high tide mark form the rim, characterized by several carbonate lithofacies, including oolites with keystone vugs, high-angle trough cross bedding, seaward-dipping low angle stratification, bioturbation and fossiliferous lags, and rudstones composed of imbricated beachrock boulders. We interpret these facies as an upper shoreface to foreshore depositional setting dominated by local storm and eolian deposits. A distinct fossiliferous rudstone facies is dominated by mytilid bivalves, as well as Eustrombus, Conus, Oliva, and vermetid gastropods. X-ray powder diffraction analyses on fossil shells reveal both shells with pristine aragonite and shells with evidence of secondary calcite. Radiometric analyses of pristine aragonite material provide additional age constraints on these deposits. Understanding the formation of Little Ambergris Cay's bedrock deposits will provide important context for the island's geological history and geomorphology, aiding in our understanding of modern analogues for ancient interior platform depositional environments.

On the application of contemporary bulk sediment organic carbon isotope and geochemical datasets for Holocene sea-level reconstruction in NW Europe

NASA Astrophysics Data System (ADS)

Wilson, Graham P.

2017-10-01

Bulk organic stable carbon isotope (δ13C) and element geochemistry (total organic carbon (TOC) and organic carbon to total nitrogen (C/N)) analysis is a developing technique in Holocene relative sea-level (RSL) research. The uptake of this technique in Northern Europe is limited compared to North America, where the common existence of coastal marshes with isotopically distinctive C3 and C4 vegetation associated with well-defined inundation tolerance permits the reconstruction of RSL in the sediment record. In Northern Europe, the reduced range in δ13C values between organic matter sources in C3 estuaries can make the identification of elevation-dependent environments in the Holocene sediment record challenging and this is compounded by the potential for post-depositional alteration in bulk δ13C values. The use of contemporary regional δ13C, C/N and TOC datasets representing the range of physiographic conditions commonly encountered in coastal wetland sediment sequences opens up the potential of using absolute values of sediment geochemistry to infer depositional environments and associated reference water levels. In this paper, the application of contemporary bulk organic δ13C, C/N and TOC to reconstruct Holocene RSL is further explored. An extended contemporary regional geochemical dataset of published δ13C, C/N and TOC observations (n = 142) from tidal-dominated C3 wetland deposits (representing tidal flat, saltmarsh, reedswamp and fen carr environments) in temperate NW Europe is compiled, and procedures implemented to correct for the 13C Suess effect on contemporary δ13C are detailed. Partitioning around medoids analysis identifies two distinctive geochemical groups in the NW European dataset, with tidal flat/saltmarsh and reedswamp/fen carr environments exhibiting characteristically different sediment δ13C, C/N and TOC values. A logistic regression model is developed from the NW European dataset in order to objectively identify in the sediment record geochemical groups and, more importantly, group transitions, thus allowing the altitude of reference water levels to be determined. The application of this method in RSL research is demonstrated using the Holocene sediments of the Mersey Estuary (UK), in which δ13C, C/N and TOC variability is typical of that encountered in Holocene sediments from C3 coastal wetlands in NW Europe. Group membership was predicted with high probability in the depositional contexts studied and the accuracy of group prediction is verified by microfossil evidence. The method presented facilitates the application of δ13C, C/N and TOC analysis in RSL reconstruction studies in C3 vegetated wetlands throughout temperate NW Europe.

Trace fossils and sedimentology of a Late Cretaceous Progradational Barrier Island sequence: Bearpaw and Horseshoe Canyon Formations, Dorothy, Alberta

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saunders, T.D.; Pemberton, A.G.; Ranger, M.J.

A well-exposed example of a regressive barrier island succession crops out in the Alberta badlands along the Red Deer River Valley. In the most landward (northwestern) corner of the study area, only shallow-water and subaerial deposits are represented and are dominated by tidal inlet related facies. Seaward (southeast), water depth increases and the succession is typified by open-marine beach to offshore-related facies arranged in coarsening-upward progradational sequence. Detailed sedimentologic and ichnologic analyses of this sequence have allowed for its division into three distinct environmental zones (lower, middle, and upper). The lower zone comprises a laterally diverse assemblage of storm-influenced, lowermore » shoreface through offshore deposits. Outcrop in the northeast is dominated by thick beds of hummocky and/or swaley cross-stratified storm sand. In the southeast, storm events have only minor influence. This lower zone contains a wide diversity of well-preserved trace fossils whose distribution appears to have been influenced by gradients in wave energy, bottom stagnation, and the interplay of storm and fair-weather processes. The middle zone records deposition across an upper shoreface environment. Here, horizontal to low-angle bedding predominates, with interspersed sets of small- and large-scale cross-bedding increasing toward the top. A characteristic feature of the upper part of this zone is the lack of biogenic structures suggesting deposition in an exposed high-energy surf zone. The upper zone records intertidal to supratidal progradation of the shoreline complex. Planar-laminated sandstone forms a distinct foreshore interval above which rhizoliths and organic material become increasingly abundant, marking transition to the backshore. A significant feature of this zone is the occurrence of an intensely bioturbated interval toward the top of the foreshore.« less

Syngenetic Au on the Carlin trend: Implications for Carlin-type deposits

USGS Publications Warehouse

Emsbo, P.; Hutchinson, R.W.; Hofstra, A.H.; Volk, J.A.; Bettles, K.H.; Baschuk, G.J.; Johnson, C.A.

1999-01-01

A new type of gold occurrence recently discovered in the Carlin trend, north-central Nevada, is clearly distinct from classic Carlin-type gold ore. These occurrences are interpreted to be of sedimentary exhalative (sedex) origin because they are stratiform and predate compaction and lithification of their unaltered Devonian host rocks. They contain barite that exhibits ??34S and ??18O values identical to sulfate in Late Devonian seawater and sedex-type barite deposits. Abrupt facies changes in the host rocks strongly suggest synsedimentary faulting and foundering of the carbonate shelf during mineralization, as is characteristic of sedex deposits. Gold occurs both as native inclusions in synsedimentary base-metal sulfides and barite, and as chemical enrichments in sulfide minerals. The absence of alteration and lack of ??13C and ??18O isotopic shift of primary carbonates in these rocks is strong evidence that this gold was not introduced with classic Carlin-type mineralization. Collectively, these features show that the Devonian strata were significantly enriched in gold some 300 m.y. prior to generation of the mid-Tertiary Carlin-type deposits. These strata may have been an important, perhaps even vital, source of gold for the latter. Although gold is typically low in most Zn-Pb-rich sedex deposits, our evidence suggests that transport of gold in basinal fluids, and its subsequent deposition in the sedex environment, can be significant.

Evolution of the Tethyan Seaway during the Oligocene and Miocene: Constraints from foraminiferal faunas of the Qom Formation, Iran

NASA Astrophysics Data System (ADS)

Dabaghi sadr, Fatemeh; Schmiedl, Gerhard

2016-04-01

The Qom Formation was deposited in the central Iranian back-arc basin during the Oligocene-Miocene and documents the closure of the Tethyan Seaway. Based on sedimentological data, various depositional models have been presented for the Oligocene-Miocene successions of central Iran, Sanandaj-Sirjan and Urumieh Dokhtar magmatic arc provinces in Iran. In this study, foraminiferal faunas were studied based on a total of 146 samples from the Molkabad section, located northwest of Molkabad Mountains, and from the Navab Anticline section, located south of Kashan area. Changes in the composition of the benthic foraminiferal fauna were used to reconstruct the paleoenvironmental evolution during deposition of the Qom Formation .The Molkabad section mainly consists of limestones, calcareous marls, marls, and gypsum-bearing marls with a total thickness of 760 meters and the Navab anticline section consists of sandstone, red shale, gypsy marl and conglomerate. The Qom Formation at both sections overlies Eocene rocks with an unconformity. The studied sediments contain a variety of red algae, bryozoans and benthic and planktonic foraminifers. The distribution of index larger benthic foraminifers in Molkabad section suggests a late Oligocene (Chattian) to early Miocene (Aquitanian-Burdigalian) age, comprising the Miolepidociyclina-Miogypsinoides and Borelis melo curdica-Meandropsina iranica-schlumbergerina assemblage zones .The small benthic faunas of the Molkabad section represent typical inner-neritic depositional environments supported by the predominance of marls and algal and bryozoan limestones in this section. The preliminary bathymetric reconstruction suggests deposition of the succession in water depths commonly shallower than 50 m. The estimated values of water depth range between 36 and 94 m but the strong predominance of the genera Ammonia and Elphidium points to an even lower water depth in some intervals. For Navab anticline section the distribution of the index larger benthic foraminifers indicate a Lower Miocene (Aquitanian-Burdigalian) age. The biostratigraphic zonation is consistent with existing data from other sections of the Qom formation and appears equivalent to biozones reported from the lower and upper parts of the Asmari Formation. The textural and faunal analyses allowed for the distinction of eight microfacies for the Molkabad section representing inner and middle ramp depositional environments. Eleven different microfacies were distinguished for the Navab Anticline section representing inner, middle and outer ramp depositional environments. Key word: Qom Formation, Central basin, Oligocene-Miocene Benthic Foraminifera, Tethyan Seaway, Iran

Spatiotemporal sedimentological and petrophysical characterization of El Gueria reservoir (Ypresian) in sFAX and Gulf of Gabes Basins (SE-Tunisia)

NASA Astrophysics Data System (ADS)

Nadhem, Kassabi; Zahra, Njahi; Ménendez, Béatriz; Salwa, Jeddi; Jamel, Touir

2017-06-01

El Gueria carbonate Formation (Ypresian) in Tunisia is a proven hydrocarbon reservoir. In the Gulf of Gabes, El Gueria reservoir consists mainly of a nummulitic limestone which is developed in an inner shelf environment. In order to characterize the depositional facies evolution and the petrophysical parameters, and to understand the origin of heterogeneity of El Gueria reservoir, we firstly conducted a sedimentological and a sequence stratigraphy study of this Formation in more than 10 wells especially in P1, then we established a detailed petrophysical study of El Gueria reservoir in P1, P3c and P7d cores. Based on lithostratigraphic and gamma ray correlations of an important number of wells in the study area, a detailed sedimentological study has been established. This latter shows that: (i): The Ypresien deposits are deposited in an inner shelf (El Gueria Formation) in the south and in an outer shelf (Boudabbous Formation) in the north of the study area with the form of horsts and grabens, (ii): 3 distinct members and 7 principal facies within El Gueria Formation have been distinguished. The coupling of data logging and data of the P1 core shows that the El Gueria deposits include 10 transgressive-regressive depositional sequences, while showing from bottom to top a broad regressive tendancy from a subtidal domain during the early Ypresian to an intertidal domain during the middle Ypresian reaching the supratidal environnement during the late Ypresian-early Lutetian. The petrophysical parameters (porosity and permeability) of El Gueria reservoir vary in time and space (laterally and vertically variation) following the deposit environment variation. Particularly, the porosity variation is controlled by eustatic cycles so that high porosities are linked with transgressive phases and low porosities with regressive phases. In addition, the vertical evolution of porosity through the El Gueria reservoir varies following the (i) deposit environments, (ii) type and morphology of nummulites such as large nummulites are more porous than small nummulites and nummilithoclastes (iii) matrix and cement such as micrite are more porous than sparite (iv) microfacies and diagenetic structures (Fractures, stylolithic seals …) such as the fractured wackstone are the most porous and permeable.

5 CFR 842.307 - Deposits for military service.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 5 Administrative Personnel 2 2010-01-01 2010-01-01 false Deposits for military service. 842.307... Deposits for military service. (a) Eligibility to make a deposit. (1) An employee or Member subject to FERS may make a deposit for any distinct period of military service by filing an application in a form...

Stratigraphic evolution of the inner continental shelf in response to late Quaternary relative sea-level change, northwestern Gulf of Maine

USGS Publications Warehouse

Barnhardt, W.A.; Belknap, D.F.; Kelley, J.T.

1997-01-01

Accumulations of deltaic and littoral sediments on the inner continental shelf of Maine, Gulf of Maine, preserve a record of postglacial sea-level changes and shoreline migrations. The depositional response of coastal environments to a cycle of regression, lowstand, and transgression was examined with seismic-reflection profiles, vibracores, and radiocarbon dates collected from sediments at the mouths of the Kennebec and Penobscot Rivers. Sequence-stratigraphie analysis of these data reveals two distinctly different successions of late Quaternary deposits that represent end members in an evolutionary model for this glaciated coast. Seaward of the Kennebec River, coarsegrained shorelines with foreset beds occur at depths of 20-60 m and outline the lobate margin of the Kennebec River paleodelta, a complex, rock-framed accumulation of glaciomarine and deltaic sediments capped by estuarine and marine deposits. Sand derived from this system today supports large barrier spits and extensive salt marshes. In contrast, the mouth of the Penobscot River is characterized by thick deposits of glaciomarine mud overlain by marine mud of Holocene age, including gas-charged zones that have locally evolved into fields of pockmarks. The distinct lack of sand and gravel seaward of the Penobscot River and its abundance seaward of the Kennebec River probably reflect differences in sediment sources and the physiography of the two watersheds. The contrasting stratigraphie framework of these systems demonstrates the importance of understanding local and regional differences in sediment supply, sea-level change, bedrock structure, and exposure to waves and tides in order to model river-mouth deposition on glaciated coasts. Evolution of shelf deposits was largely controlled by relative sea level, which locally fell from a highstand (+60 to +70 m at 14 ka) contemporary with deglaciation to a lowstand (-55 m at 10.8 ka). The sea-level lowering was accompanied by fluvial incision of older deposits, producing a regressive, basal unconformity. Major rivers deposited abundant sediment over this surface. Sea level then rose at varying rates, extensively reworking formerly emergent parts of the shelf and producing a shoreface ravinement surface in areas exposed to waves. A tidal ravinement surface has developed in sheltered embayments where erosion is due mainly to tidal currents. Incised valleys in both settings preserve transgressive estuarine deposits that contain lagoonal bivalves and salt-marsh foraminifera at depths of 15-30 m. These deposits accumulated ca. 9.2-7.3 ka, locally a period of relatively slow sea-level rise.

Geochemistry, petrology, and palynology of the Pond Creek coal bed, northern Pike and southern Martin counties, Kentucky

USGS Publications Warehouse

Hower, J.C.; Ruppert, L.F.; Eble, C.F.; Clark, W.L.

2005-01-01

The geochemistry, petrology, and palynology of the Duckmantian-age Pond Creek coal bed were investigated in northern Pike and southern Martin counties, eastern Kentucky. The coal bed exhibits significant vertical variation in the investigated geochemical parameters, with many diagenetic overprints of the original geochemistry. Included in the range of geochemical signatures are the presence of elements, particularly TiO2 and Zr, suggesting the detrital influences at the time of deposition of a low-vitrinite durain; a high CaO zone with elevated B/Be, both suggesting marine influence, in a lithotype in the middle of the coal bed; and the postdepositional emplacement of pyrite in the uppermost lithotype. Individual lithotypes, each representing distinct depositional environments, all complicated to some degree by diagentic overprints, comprise the complex history of the coal bed. ?? 2004 Elsevier B.V. All rights reserved.

Faunal composition and organic surface encrustations at hydrothermal vents on the southern Juan De Fuca Ridge

NASA Astrophysics Data System (ADS)

Tunnicliffe, Verena; Fontaine, A. R.

1987-10-01

Examination of a small collection of macroinvertebrates from three vents of the southern Juan de Fuca vent field reveals differences between the vents with respect to species composition, species habits, and microbial and metallic deposits on their surfaces. TWo apparently new vestimentiferan species were found, and for the first time the Juan de Fuca palm worm was observed to dwell on smokers. High acidity values recorded in this system may interfere with the process of shell calcification in an archaeogastropod snail. The surfaces of vestimentifer an tubes at two vents are heavily encrusted with microbial and metallic accumulations. Scanning electron microscope, transmission electron microscope, and energy dispersive X ray microanalysis observations show that iron-based crusts on orange tubes are built from accumulations of an Fe-rich particle of distinctive size and shape. Morphological evidence is presented for the microbial origin of Fe-rich particles. Zn-rich particles found on black tubes are not of microbial origin. We suggest that iron deposition on surfaces in the vent environment is initially biocatalytic but subsequent deposits may build by simple inorganic reactions.

Fine-Grained Turbidites: Facies, Attributes and Process Implications

NASA Astrophysics Data System (ADS)

Stow, Dorrik; Omoniyi, Bayonle

2016-04-01

Within turbidite systems, fine-grained sediments are still the poor relation and sport several contrasting facies models linked to process of deposition. These are volumetrically the dominant facies in deepwater and, from a resource perspective, they form important marginal and tight reservoirs, and have great potential for unconventional shale gas, source rocks and seals. They are also significant hosts of metals and rare earth elements. Based on a large number of studies of modern, ancient and subsurface systems, including 1000s of metres of section logging, we define the principal genetic elements of fine-grained deepwater facies, present a new synthesis of facies models and their sedimentary attributes. The principal architectural elements include: non-channelised slope-aprons, channel-fill, channel levee and overbank, turbidite lobes, mass-transport deposits, contourite drifts, basin sheets and drapes. These comprise a variable intercalation of fine-grained facies - thin-bedded and very thin-bedded turbidites, contourites, hemipelagites and pelagites - and associated coarse-grained facies. Characteristic attributes used to discriminate between these different elements are: facies and facies associations; sand-shale ratio, sand and shale geometry and dimensions, sand connectivity; sediment texture and small-scale sedimentary structures; sediment fabric and microfabric; and small-scale vertical sequences of bed thickness. To some extent, we can relate facies and attribute characteristics to different depositional environments. We identify four distinct facies models: (a) silt-laminated mud turbidites, (b) siliciclastic mud turbidites, (c) carbonate mud turbidites, (d) disorganized silty-mud turbidites, and (e) hemiturbidites. Within the grainsize-velocity matrix turbidite plot, these all fall within the region of mean size < 0.063mm, maximum grainsize (one percentile) <0.2mm, and depositional velocity 0.1-0.5 m/s. Silt-laminated turbidites and many mud turbidites reflect uniform, steady flow characteristics and a depositional sorting mechanism for silt-clay separation; whereas disorganized turbidites reflect an unsteady flow type, either as a short-lived surge or as a mud-contaminated mid-flow. Fine-grained carbonate turbidites show certain distinctive characteristics linked to the different dynamic behaviour of fine carbonate material. Hemiturbidites are the result of long-distance transport and an upward buoyancy mechanism during deposition.

Kisameet Glacial Clay: an Unexpected Source of Bacterial Diversity.

PubMed

Svensson, Sarah L; Behroozian, Shekooh; Xu, Wanjing; Surette, Michael G; Li, Loretta; Davies, Julian

2017-05-23

Widespread antibiotic resistance among bacterial pathogens is providing the impetus to explore novel sources of antimicrobial agents. Recently, the potent antibacterial activity of certain clay minerals has stimulated scientific interest in these materials. One such example is Kisameet glacial clay (KC), an antibacterial clay from a deposit on the central coast of British Columbia, Canada. However, our understanding of the active principles of these complex natural substances is incomplete. Like soils, clays may possess complex mixtures of bacterial taxa, including the Actinobacteria , a clade known to be rich in antibiotic-producing organisms. Here, we present the first characterization of both the microbial and geochemical characteristics of a glacial clay deposit. KC harbors surprising bacterial species richness, with at least three distinct community types. We show that the deposit has clines of inorganic elements that can be leached by pH, which may be drivers of community structure. We also note the prevalence of Gallionellaceae in samples recovered near the surface, as well as taxa that include medically or economically important bacteria such as Actinomycetes and Paenibacillus These results provide insight into the microbial taxa that may be the source of KC antibacterial activity and suggest that natural clays may be rich sources of microbial and molecular diversity. IMPORTANCE Identifying and characterizing the resident microbial populations (bacteria, viruses, protozoa, and fungi) is key to understanding the ecology, chemistry, and homeostasis of virtually all sites on Earth. The Kisameet Bay deposit in British Columbia, Canada, holds a novel glacial clay with a history of medicinal use by local indigenous people. We previously showed that it has potent activity against a variety of antibiotic-resistant bacteria, suggesting it could complement our dwindling arsenal of antibiotics. Here, we have characterized the microbiome of this deposit to gain insight into what might make the clay antibacterial. Our analyses suggest that the deposit contains a surprising diversity of bacteria, which live in at least three distinct environments. In addition, the clay harbors bacteria that may have interesting potential as biocontrol/bioremediation agents or producers of novel bioactive compounds. Copyright © 2017 Svensson et al.

The discovery and character of Pleistocene calcrete uranium deposits in the Southern High Plains of west Texas, United States

USGS Publications Warehouse

Van Gosen, Bradley S.; Hall, Susan M.

2017-12-18

This report describes the discovery and geology of two near-surface uranium deposits within calcareous lacustrine strata of Pleistocene age in west Texas, United States. Calcrete uranium deposits have not been previously reported in the United States. The west Texas uranium deposits share characteristics with some calcrete uranium deposits in Western Australia—uranium-vanadium minerals hosted by nonpedogenic calcretes deposited in saline lacustrine environments.In the mid-1970s, Kerr-McGee Corporation conducted a regional uranium exploration program in the Southern High Plains province of the United States, which led to the discovery of two shallow uranium deposits (that were not publicly reported). With extensive drilling, Kerr-McGee delineated one deposit of about 2.1 million metric tons of ore with an average grade of 0.037 percent U3O8 and another deposit of about 0.93 million metric tons of ore averaging 0.047 percent U3O8.The west-Texas calcrete uranium-vanadium deposits occur in calcareous, fine-grained sediments interpreted to be deposited in saline lakes formed during dry interglacial periods of the Pleistocene. The lakes were associated with drainages upstream of a large Pleistocene lake. Age determinations of tephra in strata adjacent to one deposit indicate the host strata is middle Pleistocene in age.Examination of the uranium-vanadium mineralization by scanning-electron microscopy indicated at least two generations of uranium-vanadium deposition in the lacustrine strata identified as carnotite and a strontium-uranium-vanadium mineral. Preliminary uranium-series results indicate a two-component system in the host calcrete, with early lacustrine carbonate that was deposited (or recrystallized) about 190 kilo-annum, followed much later by carnotite-rich crusts and strontium-uranium-vanadium mineralization in the Holocene (about 5 kilo-annum). Differences in initial 234U/238U activity ratios indicate two separate, distinct fluid sources.

Lakshmi Planum: A distinctive highland volcanic province

NASA Astrophysics Data System (ADS)

Roberts, Kari M.; Head, James W.

Lakshmi Planum, a broad smooth plain located in western Ishtar Terra and containing two large oval depressions (Colette and Sacajawea), has been interpreted as a highland plain of volcanic origin. Lakshmi is situated 3 to 5 km above the mean planetary radius and is surrounded on all sides by bands of mountains interpreted to be of compressional tectonic origin. Four primary characteristics distinguish Lakshmi from other volcanic regions known on the planet, such as Beta Regio: (1) high altitude, (2) plateau-like nature, (3) the presence of very large, low volcanic constructs with distinctive central calderas, and (4) its compressional tectonic surroundings. Building on the previous work of Pronin, the objective is to establish the detailed nature of the volcanic deposits on Lakshmi, interpret eruption styles and conditions, sketch out an eruption history, and determine the relationship between volcanism and the tectonic environment of the region.

Lakshmi Planum: A distinctive highland volcanic province

NASA Technical Reports Server (NTRS)

Roberts, Kari M.; Head, James W.

1989-01-01

Lakshmi Planum, a broad smooth plain located in western Ishtar Terra and containing two large oval depressions (Colette and Sacajawea), has been interpreted as a highland plain of volcanic origin. Lakshmi is situated 3 to 5 km above the mean planetary radius and is surrounded on all sides by bands of mountains interpreted to be of compressional tectonic origin. Four primary characteristics distinguish Lakshmi from other volcanic regions known on the planet, such as Beta Regio: (1) high altitude, (2) plateau-like nature, (3) the presence of very large, low volcanic constructs with distinctive central calderas, and (4) its compressional tectonic surroundings. Building on the previous work of Pronin, the objective is to establish the detailed nature of the volcanic deposits on Lakshmi, interpret eruption styles and conditions, sketch out an eruption history, and determine the relationship between volcanism and the tectonic environment of the region.

The Australian Paleoflood Model for Unconfined Fluvial Deposition on Mars

NASA Technical Reports Server (NTRS)

Bourke, M. C.; Zimbelman, J. R.

2001-01-01

Paleoflood deposits in central Australia represent a new model for possible fluvial deposits on Mars. The distinct Australian assemblage of landforms and sediments is used to identify potential unconfined paleoflood deposits in Mars Orbiter Camera (MOC) images of Mars. Additional information is contained in the original extended abstract.

Characterization of the Etna volcanic emissions through an active biomonitoring technique (moss-bags): part 1--major and trace element composition.

PubMed

Calabrese, S; D'Alessandro, W; Bellomo, S; Brusca, L; Martin, R S; Saiano, F; Parello, F

2015-01-01

Active biomonitoring using moss-bags was applied to an active volcanic environment for the first time. Bioaccumulation originating from atmospheric deposition was evaluated by exposing mixtures of washed and air-dried mosses (Sphagnum species) at 24 sites on Mt. Etna volcano (Italy). Concentrations of major and a large suite of trace elements were analysed by inductively coupled mass and optical spectrometry (ICP-MS and ICP-OES) after total acid digestion. Of the 49 elements analysed those which closely reflect summit volcanic emissions were S, Tl, Bi, Se, Cd, As, Cu, B, Na, Fe, Al. Enrichment factors and cluster analysis allowed clear distinction between volcanogenic, geogenic and anthropogenic inputs that affect the local atmospheric deposition. This study demonstrates that active biomonitoring with moss-bags is a suitable and robust technique for implementing inexpensive monitoring in scarcely accessible and harsh volcanic environments, giving time-averaged quantitative results of the local exposure to volcanic emissions. This task is especially important in the study area because the summit area of Mt. Etna is visited by nearly one hundred thousand tourists each year who are exposed to potentially harmful volcanic emissions. Copyright © 2014 Elsevier Ltd. All rights reserved.

Brief communication: beyond the South African cave paradigm--Australopithecus africanus from Plio-Pleistocene paleosol deposits at Taung.

PubMed

Hopley, Philip J; Herries, Andy I R; Baker, Stephanie Edwards; Kuhn, Brian F; Menter, Colin G

2013-06-01

Following the discovery of the "Taung Child" (Australopithecus africanus) in 1924 in the Buxton-Norlim Limeworks near Taung, the fossil-bearing deposits associated with the Dart and Hrdlička pinnacles have been interpreted as the mined remnants of cave sediments that formed within the Plio-Pleistocene Thabaseek Tufa: either as a younger cave-fill or as contemporaneous carapace caves. When combined with the Plio-Pleistocene dolomitic cave deposits from the "Cradle of Humankind," a rather restricted view emerges that South African early hominins derived from cave deposits, whereas those of east and central Africa are derived from fluvio-lacustrine and paleosol deposits. We undertook a sedimentological and paleomagnetic analysis of the pink-colored deposit (PCS) from which the "Taung Child" is purported to have derived and demonstrate that it is a calcrete, a carbonate-rich pedogenic sediment, which formed on the paleo-land surface. The deposit extends 100 s of meters laterally beyond the Dart and Hrdlička Pinnacles where it is interbedded with the Thabaseek Tufa, indicating multiple episodes of calcrete development and tufa growth. The presence of in situ rhizoconcretions and insect trace fossils (Celliforma sp. and Coprinisphaera sp.) and the distinctive carbonate microfabric confirm that the pink deposit is a pedogenic calcrete, not a calcified cave sediment. Paleomagnetic and stratigraphic evidence indicates that a second, reversed polarity, fossil-bearing deposit (YRSS) is a younger fissure-fill formed within a solutional cavity of the normal polarity tufa and pink calcrete (PCS). These observations have implications for the dating, environment, and taphonomy of the site, and increase the likelihood of future fossil discoveries within the Buxton-Norlim Limeworks. Copyright © 2013 Wiley Periodicals, Inc.

Genesis of Silica-Carbonate Type Mercury Ore Deposits in Coast Range California from Mantle Derived Fluids

NASA Astrophysics Data System (ADS)

Rytuba, J. J.; Kirby, S. H.; Kellner, C. R.

2016-12-01

In the Coast Range of California 51 major mercury (Hg) deposits and numerous smaller Hg occurrences began forming when subduction transitioned to the transpressive continental-transform kinematics of the San Andreas Fault System. The Hg deposits become progressively younger to the north reflecting the change in tectonic environment as the Mendocino Triple Junction moved 400 km northward since the Miocene to its present location in northern California. The silica-carbonate mercury deposits are vein and replacement ore bodies developed within and adjacent to serpentinite that was emplaced along regional faults and altered to an assemblage of silica and carbonate minerals. The initial alteration process consists of the addition of carbonate to the serpentinite followed by introduction of silica into the central core. The peripheral zone of calcite-dolomite veining may extend for several kilometers outward from a mercury deposit. The large Hg deposits formed in structural traps, such as antiformal structures, and the ores locally extend into adjacent clastic metasedimentary rocks. The mineralogy of the primary ores is simple consisting of cinnabar, metacinnabar and elemental Hg. The deposits formed from low-temperature, <120oC, CO2-CH4-H2S-rich fluids. The hydrothermal fluids are consistent with a mantle source water derived from the former forearc during subduction and after the transition to transpressive continental-transform boundary as proposed by Kirby et al. (EPS, 2014). Some of the silica-carbonate Hg deposits are overprinted by younger hot spring type Hg mineralization associated temporally with volcanic vents. These Hg deposits have distinctly different types of alteration and geochemistry and formed in the near surface from meteoric waters.

5 CFR 842.811 - Deposits for second-level supervisory air traffic controller service performed before February 10...

Code of Federal Regulations, 2011 CFR

2011-01-01

... Personnel OFFICE OF PERSONNEL MANAGEMENT (CONTINUED) CIVIL SERVICE REGULATIONS (CONTINUED) FEDERAL EMPLOYEES... made for a distinct period of service; however, such a deposit shall be ineffective if deposits are not...

5 CFR 842.811 - Deposits for second-level supervisory air traffic controller service performed before February 10...

Code of Federal Regulations, 2010 CFR

2010-01-01

... Personnel OFFICE OF PERSONNEL MANAGEMENT (CONTINUED) CIVIL SERVICE REGULATIONS (CONTINUED) FEDERAL EMPLOYEES... made for a distinct period of service; however, such a deposit shall be ineffective if deposits are not...

Changes in Depositional Setting Reflect Rising Sealevel in Latest Holocene Sediments of the Hudson River

NASA Astrophysics Data System (ADS)

Slagle, A.; Carbotte, S. M.; Ryan, W. B.; Bell, R.; Nitsche, F. O.; McHugh, C. M.

2002-12-01

An extensive database of geophysical and sampling data in the Hudson River has been obtained in ten study areas between the New York Harbor and the Troy Dam. These data include bathymetry, bank-to-bank coverage of side-looking sonar imagery, subbottom reflection profiles, sediment cores and grabs. Geophysical properties, including gamma density, magnetic susceptibility and P-wave velocity, have been measured in a 9.3 m Vibracore (SD-30) from the near-channel tidal flats of the Tappan Zee area. Three distinct sedimentary facies have been identified, based on changes in physical properties, lithology and seismic reflections. Facies 1 is an oyster-rich unit with unstratified sediments and high sound velocities, and is found in the upper 1.5 m of core SD-30. Chirp subbottom data, which provide reflectors down to approximately 4 m depth, show a distinct horizon at 1.5 m, supporting the change seen in physical property data and lithology at this depth. A unit characterized by laminated sediments, interbedded with homogeneous layers and coquina layers, is identified as Facies 2 and is found between 1.5 and 6.1 m. This facies has high magnetic susceptibility and the appearance of discrete density cycles. The oldest unit, Facies 3, extends from 6.1 m to the base of the core at 9.3 m. It is made up of oyster-rich, unbedded sediments and thick coquina layers, and is characterized by low magnetic susceptibility. Radiocarbon dating of oysters and bivalves indicates that the different facies in SD-30 correspond to different sedimentation rates, with highest values occurring during deposition of Facies 2. The facies changes and variations in sedimentation rates are attributed to an evolving depositional environment in the tidal flats of the Tappan Zee area due to rising sealevel. Extrapolating from nearby cores that penetrate deeper into the sedimentary record, Facies 3 sits above post-glacial fluvial sands and represents the transition from a fresh to more brackish environment, suitable for development of oyster beds. The laminated sediments of Facies 2 are attributed to infilling of the tidal flats during a rapid rise in sealevel. The lack of laminated sediments and low sedimentation rates of Facies 1 are attributed to the modern wave-base dominated depositional setting in the Tappan Zee area.

Interpreting the deposition and vertical migration characteristics of 137Cs in forest soil after the Fukushima Dai-ichi Nuclear Power Plant accident.

PubMed

Kang, Seongjoo; Yoneda, Minoru; Shimada, Yoko; Satta, Naoya; Fujita, Yasutaka; Shin, In Hwan

2017-08-01

We investigated the deposition and depth distributions of radiocesium in the Takizawa Research Forest, Iwate Prefecture, in order to understand the behavior of radionuclides released from the Fukushima Dai-ichi Nuclear Power Plant. The deposition distribution and vertical depth distribution of radiocesium in the soil were compared between topographically distinct parts of the forest where two different tree species grow. The results for all investigated locations show that almost 85% of the radiocesium has accumulated in the region of soil from the topmost organic layer to a soil depth of 0-4 cm. However, no activity was detected at depths greater than 20 cm. Analysis of the radiocesium deposition patterns in forest locations dominated by either coniferous or deciduous tree species suggests that radiocesium was sequestered and retained in higher concentrations in coniferous areas. The deposition data showed large spatial variability, reflecting the differences in tree species and topography. The variations in the measured 137 Cs concentrations reflected the variability in the characteristics of the forest floor environment and the heterogeneity of the initial ground-deposition of the Fukushima fallout. Sequential extraction experiments showed that most of the 137 Cs was present in an un-exchangeable form with weak mobility. Nevertheless, the post-vertical distribution of 137 Cs is expected to be governed by the percentage of exchangeable 137 Cs in the organic layer and the organic-rich upper soil horizons.

Lithology, petrography and Cu occurrence of the Neoproterozoic glacial Mwale Formation at the Shanika syncline (Tenke Fungurume, Congo Copperbelt; Democratic Republic of Congo)

NASA Astrophysics Data System (ADS)

Mambwe, Pascal; Milan, Luke; Batumike, Jacques; Lavoie, Sébastien; Jébrak, Michel; Kipata, Louis; Chabu, Mumba; Mulongo, Sonya; Lubala, Toto; Delvaux, Damien; Muchez, Philippe

2017-05-01

The Mwale Formation that constitutes the base of the Nguba Group in the Neoproterozoic Katanga Supergroup has recently attracted renewed interest for copper mineral exploration. We present new field observations combined with detailed logging and petrography of MWAS0001 drill hole at Shanika syncline in the Tenke Fungurume Mining District. Our study has enabled us to subdivide the Mwale Formation into 7 distinct sequences. This succession is host to glaciogenic, glaciomarine, glaciofluvial and glaciolacustrine deposits. Glaciomarine beds are typically a deposit by debris flow in deep water marine environment, induced by basin wide tectonics and glaciation influence. Glaciofluvial beds were deposited in shallow water, fluvial deltaic environment. The glaciolacustrine environment is indicated by dropstones occurring in the laminated mudstone and rhythmites with dispersed clasts observed in the siltstone and conglomerate. These beds are interlayered within the glaciogenic beds, and are characterised by variable clast composition (felsic, mafic and metamorphic). The clasts are very poorly sorted, angular, rounded to moderately rounded, faceted or striated, and supported in a sandy argillaceous or mud matrix. Two main episodes of sulphide mineralisation are distinguished in the Mwale Formation. The diagenetic episode consists of disseminated euhedral and framboidal pyrites. The hydrothermal episode is associated with Mg-metasomatism and characterised by low grade copper mineralisation that occurs (i) in veins filled with carbonate-chlorite and carbonate-quartz-chlorite-Cu sulphides, such as chalcocite, chalcopyrite and bornite, and (ii) as disseminated sulphides within the host rock. This second episode is late to post-orogenic and can be correlated with late brittle tectonics within the Lufilian arc. The other alteration types include silicification and potassic alteration; however, these alterations are not associated with mineralisation.

Paleoecology and paleoceanography of the Athel silicilyte, Ediacaran-Cambrian boundary, Sultanate of Oman.

PubMed

Stolper, D A; Love, G D; Bates, S; Lyons, T W; Young, E; Sessions, A L; Grotzinger, J P

2017-05-01

The Athel silicilyte is an enigmatic, hundreds of meters thick, finely laminated quartz deposit, in which silica precipitated in deep water (>~100-200 m) at the Ediacaran-Cambrian boundary in the South Oman Salt Basin. In contrast, Meso-Neoproterozoic sinks for marine silica were dominantly restricted to peritidal settings. The silicilyte is known to contain sterane biomarkers for demosponges, which today are benthic, obligately aerobic organisms. However, the basin has previously been described as permanently sulfidic and time-equivalent shallow-water carbonate platform and evaporitic facies lack silica. The Athel silicilyte thus represents a unique and poorly understood depositional system with implications for late Ediacaran marine chemistry and paleoecology. To address these issues, we made petrographic observations, analyzed biomarkers in the solvent-extractable bitumen, and measured whole-rock iron speciation and oxygen and silicon isotopes. These data indicate that the silicilyte is a distinct rock type both in its sedimentology and geochemistry and in the original biology present as compared to other facies from the same time period in Oman. The depositional environment of the silicilyte, as compared to the bounding shales, appears to have been more reducing at depth in sediments and possibly bottom waters with a significantly different biological community contributing to the preserved biomarkers. We propose a conceptual model for this system in which deeper, nutrient-rich waters mixed with surface seawater via episodic mixing, which stimulated primary production. The silica nucleated on this organic matter and then sank to the seafloor, forming the silicilyte in a sediment-starved system. We propose that the silicilyte may represent a type of environment that existed elsewhere during the Neoproterozoic. These environments may have represented an important locus for silica removal from the oceans. © 2017 John Wiley & Sons Ltd.

Pre-Holocene to Modern Evolution of the Lower Delaware Estuary: Constraints from High-Resolution Chirp Subbottom Profiles

NASA Astrophysics Data System (ADS)

Daw, Julianne

Throughout the Quaternary Period, the Delaware Estuary, which is located within the Mid-Atlantic region of the United States, has undergone substantial change as a result of sea-level fluctuations. To better understand the recent (late Pleistocene to Holocene) evolution of the region, chirp subbottom profiles were analyzed within Delaware Bay near the southern end of the Delaware River Navigation Channel including the adjacent shoals and sloughs, using RoxAnn bottom classification data and available vibracores to aid in interpreting sediment types and depositional environments within the study area. Using seismic processing software (SonarWiz6), chirp profiles were processed and reflection events were identified and their positions digitized. Major reflection events were analyzed using a seismic facies approach. The identified facies were each characterized as distinct units composed of reflections with unique elements, such as configuration, amplitude, and continuity. Five seismic facies were identified and their thicknesses determined. Depths to the major reflection events were correlated with sediment boundaries as observed in the available vibracores, allowing the seismic facies to be interpreted in terms of their associated sediment types and inferred environments of deposition. The distributions of surficial and subsurface seismic and sedimentological features were visualized using three-dimensional images. The interpretations of the identified facies are as follows: Facies I is a surficial unit of the modern Holocene estuarine deposits; Facies II is a beach-berm washover zone deposition; Facies III is a deposit of a lagoonal environment; Facies IV is a deposit of an open water environment; and Facies V is a marsh deposition. The chirp data, when integrated with available information from vibracores and RoxAnn bottom sediment classification, was also used to map the position of a former major river system (paleochannel). This paleochannel, trending generally northwest to southeast, can be correlated with the southern channel that was identified in previous work by Knebel and Circe (1988). In addition to the knowledge gained by studying the geological evolution of Delaware Bay, our data can be used by decision makers and stakeholders to inform future management of the Delaware Estuary in practical applications that range from planning for maintenance dredging of the navigation channel to determining locations and thicknesses of suitable sand resources for shoreline replenishment. The surficial layer that would be most affected by such applications is mostly composed of sand & muddy sand, but in the deeper portions and along the shoals, it is composed of mixed and coarse sediments and mud & sandy mud, respectively. Furthermore, the surficial unit is thickest (between 1.5 and 4 meters) in the central and eastern regions of the study area encompassing the deeper portions, and it is thinnest (up to 1 meter) along the western and northern regions that include the shoals.

Bitumen II from the Paleoproterozoic Here’s Your Chance Pb/Zn/Ag deposit: Implications for the analysis of depositional environment and thermal maturity of hydrothermally-altered sediments

NASA Astrophysics Data System (ADS)

Holman, Alex I.; Grice, Kliti; Jaraula, Caroline M. B.; Schimmelmann, Arndt

2014-08-01

The formation of sedimentary exhalative (SEDEX) Pb/Zn deposits is linked to ocean euxinia, but recent evidence suggests that ferruginous conditions may have dominated the deep ocean during the Middle Proterozoic, a maximum period for SEDEX distribution. Biomarkers of sulfate-reducing and sulfide-oxidising bacteria are valuable indicators of euxinic conditions in such settings. Organic matter (OM) from SEDEX deposits is often affected by alteration and/or migration, but OM entrapped within the kerogen/mineral matrix (Bitumen II) may be less affected than the freely-extractable OM (Bitumen I). We analysed Bitumen II from the Paleoproterozoic Here’s Your Chance (HYC) Pb/Zn/Ag deposit to find evidence of euxinic conditions in the depositional environment. n-Alkane distributions in Bitumen II are markedly distinct from previously-reported Bitumen I. Bitumen II contains long-chain n-alkanes (up to C36 or C38) and a strong even-over-odd distribution in a number of samples, which are 4‰ to 7‰ depleted in 13C compared to n-alkanes in Bitumen I and verified as indigenous by comparison with δ13C of isolated kerogen. These features are interpreted as evidence of sulfate-reducing and sulfide-oxidising bacteria, confirming that HYC was deposited under euxinic conditions. Bitumen II has the potential to reveal information from OM that is degraded and/or overprinted in Bitumen I. Commonly-used methylphenanthrene maturity ratios give conflicting information as to the relative maturity of Bitumens I and II. Bitumen I contains a far higher proportion of methylated phenanthrenes than Bitumen II. As Bitumen II is sequestered within the kerogen/mineral matrix it may have restricted access to the ‘methyl pool’ of organic compounds that can donate methyl groups to aromatic hydrocarbons. Parameters that include both phenanthrene and methylphenanthrenes do not appear suitable to compare the maturity of Bitumens I and II; hence there is no clear evidence that Bitumen II is of lower thermal maturity than Bitumen I.

Three depositional states and sedimentary processes of the western Taiwan foreland basin system

NASA Astrophysics Data System (ADS)

Lin, Yi-Jung; Wu, Pei-Jen; Yu, Ho-Shing

2010-05-01

The western Taiwan foreland basin formed during the Early Pliocene as the flexural response to the loading of Taiwan orogen on the Eurasian plate. What makes Taiwan interesting is the oblique collision, which allows the foreland basin to be seen at different stages in its evolution at the present day. Due to oblique arc-continent collision from north to south, the western Taiwan foreland basin has evolved into three distinct subbasins: an over-filled basin proximal to the Taiwan orogen, mainly distributed in the Western Foothills and Coastal Plain provinces, a filled basin occupying the shallow Taiwan Strait continental shelf west of the Taiwan orogen and an under-filled basin distal to the Taiwan orogen in the deep marine Kaoping Slope offshore southwest Taiwan, respectively. The over-filled depositional phase is dominated by fluvial environments across the structurally controlled piggy-back basins. The filled depositional state in the Taiwan Strait is characterized by shallow marine environments and is filled by Pliocene-Quaternary sediments up to 4,000 m thick derived from the Taiwan orogen with an asymmetrical and wedge-shaped cross section. The under-filled depositional state is characteristic of deep marine environments in the wedge-top basins accompanied by active structures of thrust faults and mud diapers. Sediments derived from the Taiwan orogen have progressively filled the western Taiwan foreland basin across and along the orogen. Sediment dispersal model suggests that orogenic sediments derived from oblique dischronous collisional highlands are transported in two different ways. Transport of fluvial and shallow marine sediments is perpendicular to hill-slope and across-strike in the fluvial and shallow marine environments proximal to the orogen. Fine-grained sediments mainly longitudinally transported into the deep marine environments distal to the orogen. The present sedimentary processes in the over-filled basin on land are dominated by fluvial processes of small mountainous rivers. Tidal currents are prevalent in the filled basin in Taiwan Strait, transporting shelf sands and forming sand ridges. The deep marine under-filled basin are dominated by down-slope mass wasting processes, eroding slope strata and transporting sediments to the basin floor. In addition, many submarine canyons on the continental slope offshore southwest Taiwan serve as major sediment pathways, delivering shallow marine sediments to the basin floor.

Gold and trace element zonation in pyrite using a laser imaging technique: Implications for the timing of gold in orogenic and carlin-style sediment-hosted deposits

USGS Publications Warehouse

Large, R.R.; Danyushevsky, L.; Hollit, C.; Maslennikov, V.; Meffre, S.; Gilbert, S.; Bull, S.; Scott, R.; Emsbo, P.; Thomas, H.; Singh, B.; Foster, J.

2009-01-01

Laser ablation ICP-MS imaging of gold and other trace elements in pyrite from four different sediment- hosted gold-arsenic deposits has revealed two distinct episodes of gold enrichment in each deposit: an early synsedimentary stage where invisible gold is concentrated in arsenian diagenetic pyrite along with other trace elements, in particular, As, Ni, Pb, Zn, Ag, Mo, Te, V, and Se; and a later hydrothermal stage where gold forms as either free gold grains in cracks in overgrowth metamorphic and/or hydrothermal pyrite or as narrow gold- arsenic rims on the outermost parts of the overgrowth hydrothermal pyrite. Compared to the diagenetic pyrites, the hydrothermal pyrites are commonly depleted in Ni, V, Zn, Pb, and Ag with cyclic zones of Co, Ni, and As concentration. The outermost hydrothermal pyrite rims are either As-Au rich, as in moderate- to high- grade deposits such as Carlin and Bendigo, or Co-Ni rich and As-Au poor as in moderate- to low-grade deposits such as Sukhoi Log and Spanish Mountain. The early enrichment of gold in arsenic-bearing syngenetic to diagenetic pyrite, within black shale facies of sedimentary basins, is proposed as a critical requirement for the later development of Carlin-style and orogenic gold deposits in sedimentary environments. The best grade sediment-hosted deposits appear to have the gold climax event, toward the final stages of deformation-related hydrothermal pyrite growth and fluid flow. ?? 2009 Society of Economic Geologists, Inc.

Depositional facies, environments and sequence stratigraphic interpretation of the Middle Triassic-Lower Cretaceous (pre-Late Albian) succession in Arif El-Naga anticline, northeast Sinai, Egypt

NASA Astrophysics Data System (ADS)

El-Azabi, M. H.; El-Araby, A.

2005-01-01

The Middle Triassic-Lower Cretaceous (pre-Late Albian) succession of Arif El-Naga anticline comprises various distinctive facies and environments that are connected with eustatic relative sea-level changes, local/regional tectonism, variable sediment influx and base-level changes. It displays six unconformity-bounded depositional sequences. The Triassic deposits are divided into a lower clastic facies (early Middle Triassic sequence) and an upper carbonate unit (late Middle- and latest Middle/early Late Triassic sequences). The early Middle Triassic sequence consists of sandstone with shale/mudstone interbeds that formed under variable regimes, ranging from braided fluvial, lower shoreface to beach foreshore. The marine part of this sequence marks retrogradational and progradational parasequences of transgressive- and highstand systems tract deposits respectively. Deposition has taken place under warm semi-arid climate and a steady supply of clastics. The late Middle- and latest Middle/early Late Triassic sequences are carbonate facies developed on an extensive shallow marine shelf under dry-warm climate. The late Middle Triassic sequence includes retrogradational shallow subtidal oyster rudstone and progradational lower intertidal lime-mudstone parasequences that define the transgressive- and highstand systems tracts respectively. It terminates with upper intertidal oncolitic packstone with bored upper surface. The next latest Middle/early Late Triassic sequence is marked by lime-mudstone, packstone/grainstone and algal stromatolitic bindstone with minor shale/mudstone. These lower intertidal/shallow subtidal deposits of a transgressive-systems tract are followed upward by progradational highstand lower intertidal lime-mudstone deposits. The overlying Jurassic deposits encompass two different sequences. The Lower Jurassic sequence is made up of intercalating lower intertidal lime-mudstone and wave-dominated beach foreshore sandstone which formed during a short period of rising sea-level with a relative increase in clastic supply. The Middle-Upper Jurassic sequence is represented by cycles of cross-bedded sandstone topped with thin mudstone that accumulated by northerly flowing braided-streams accompanying regional uplift of the Arabo-Nubian shield. It is succeeded by another regressive fluvial sequence of Early Cretaceous age due to a major eustatic sea-level fall. The Lower Cretaceous sequence is dominated by sandy braided-river deposits with minor overbank fines and basal debris flow conglomerate.

The use of LANDSAT imagery in relation to air survey imagery for terrain analysis in northwest Queensland, Australia, volume 1

NASA Technical Reports Server (NTRS)

Cole, M. M.; Owen-Jones, E. S. (Principal Investigator)

1977-01-01

The author has identified the following significant results. Distinctive spectral signatures discriminated areas underlain by distinctive lithological/stratigraphical units where bedrock either outcrops or is relatively near to surface in the Lady Annie-Mt. Gordon fault zone, the Mary Kathleen, and Dugald River-Naraku areas. Spectral signatures associated with discrete plant communities distinguished different types of superficial deposits over the Cloncurry Plains. Distinctive spectral signatures also revealed the presence and nature of concealed bedrock beneath cover of residuum and superficial deposits where this is relatively thin in the Cloncurry Plains. Major faults were clearly displayed in areas of outcropping and near surface bedrock. Sets of lineaments with preferred orientations were identified in the Lady Annie and Dugald River areas. Known base metal deposits occur along these features.

Assessing Reservoir Depositional Environments to Develop and Quantify Improvements in CO 2 Storage Efficiency. A Reservoir Simulation Approach

DOE Office of Scientific and Technical Information (OSTI.GOV)

Okwen, Roland; Frailey, Scott; Leetaru, Hannes

2014-09-30

The storage potential and fluid movement within formations are dependent on the unique hydraulic characteristics of their respective depositional environments. Storage efficiency (E) quantifies the potential for storage in a geologic depositional environment and is used to assess basinal or regional CO 2 storage resources. Current estimates of storage resources are calculated using common E ranges by lithology and not by depositional environment. The objectives of this project are to quantify E ranges and identify E enhancement strategies for different depositional environments via reservoir simulation studies. The depositional environments considered include deltaic, shelf clastic, shelf carbonate, fluvial deltaic, strandplain, reef,more » fluvial and alluvial, and turbidite. Strategies considered for enhancing E include CO 2 injection via vertical, horizontal, and deviated wells, selective completions, water production, and multi-well injection. Conceptual geologic and geocellular models of the depositional environments were developed based on data from Illinois Basin oil fields and gas storage sites. The geologic and geocellular models were generalized for use in other US sedimentary basins. An important aspect of this work is the development of conceptual geologic and geocellular models that reflect the uniqueness of each depositional environment. Different injection well completions methods were simulated to investigate methods of enhancing E in the presence of geologic heterogeneity specific to a depositional environment. Modeling scenarios included horizontal wells (length, orientation, and inclination), selective and dynamic completions, water production, and multiwell injection. A Geologic Storage Efficiency Calculator (GSECalc) was developed to calculate E from reservoir simulation output. Estimated E values were normalized to diminish their dependency on fluid relative permeability. Classifying depositional environments according to normalized baseline E ranges ranks fluvial deltaic and turbidite highest and shelf carbonate lowest. The estimated average normalized baseline E of turbidite, and shelf carbonate depositional environments are 42.5% and 13.1%, with corresponding standard deviations of 11.3%, and 3.10%, respectively. Simulations of different plume management techniques suggest that the horizontal well, multi-well injection with brine production from blanket vertical producers are the most efficient E enhancement strategies in seven of eight depositional environments; for the fluvial deltaic depositional environment, vertical well with blanket completions is the most efficient. This study estimates normalized baseline E ranges for eight depositional environments, which can be used to assess the CO 2 storage resource of candidate formations. This study also improves the general understanding of depositional environment’s influence on E. The lessons learned and results obtained from this study can be extrapolated to formations in other US basins with formations of similar depositional environments, which should be used to further refine regional and national storage resource estimates in future editions of the Carbon Utilization and Storage Atlas of the United States. Further study could consider the economic feasibility of the E enhancement strategies identified here.« less

Imbalance in Fatty-Acid-Chain Length of Gangliosides Triggers Alzheimer Amyloid Deposition in the Precuneus

PubMed Central

Oikawa, Naoto; Matsubara, Teruhiko; Fukuda, Ryoto; Yasumori, Hanaki; Hatsuta, Hiroyuki; Murayama, Shigeo; Sato, Toshinori; Suzuki, Akemi; Yanagisawa, Katsuhiko

2015-01-01

Amyloid deposition, a crucial event of Alzheimer’s disease (AD), emerges in distinct brain regions. A key question is what triggers the assembly of the monomeric amyloid ß-protein (Aß) into fibrils in the regions. On the basis of our previous findings that gangliosides facilitate the initiation of Aß assembly at presynaptic neuritic terminals, we investigated how lipids, including gangliosides, cholesterol and sphingomyelin, extracted from synaptic plasma membranes (SPMs) isolated from autopsy brains were involved in the Aß assembly. We focused on two regions of the cerebral cortex; precuneus and calcarine cortex, one of the most vulnerable and one of the most resistant regions to amyloid deposition, respectively. Here, we show that lipids extracted from SPMs isolated from the amyloid-bearing precuneus, but neither the amyloid-free precuneus nor the calcarine cortex, markedly accelerate the Aß assembly in vitro. Through liquid chromatography-mass spectrometry of the lipids, we identified an increase in the ratio of the level of GD1b-ganglioside containing C20:0 fatty acid to that containing C18:0 as a cause of the enhanced Aß assembly in the precuneus. Our results suggest that the local glycolipid environment play a critical role in the initiation of Alzheimer amyloid deposition. PMID:25798597

Braided fluvial sedimentation in the lower paleozoic cape basin, South Africa

NASA Astrophysics Data System (ADS)

Vos, Richard G.; Tankard, Anthony J.

1981-07-01

Lower Paleozoic braided stream deposits from the Piekenier Formation in the Cape Province, South Africa, provide information on lateral and vertical facies variability in an alluvial plain complex influenced by a moderate to high runoff. Four braided stream facies are recognized on the basis of distinct lithologies and assemblages of sedimentary structures. A lower facies, dominated by upward-fining conglomerate to sandstone and mudstone channel fill sequences, is interpreted as a middle to lower alluvial plain deposit with significant suspended load sedimentation in areas of moderate to low gradients. These deposits are succeeded by longitudinal conglomerate bars which are attributed to middle to upper alluvial plain sedimentation with steeper gradients. This facies is in turn overlain by braid bar complexes of large-scale transverse to linguoid dunes consisting of coarse-grained pebbly sandstones with conglomerate lenses. These bar complexes are compared with environments of the Recent Platte River. They represent a middle to lower alluvial plain facies with moderate gradients and no significant suspended load sedimentation or vegetation to stabilize channels. These bar complexes interfinger basinward with plane bedded medium to coarse-grained sandstones interpreted as sheet flood deposits over the distal portions of an alluvial plain with low gradients and lacking fine-grained detritus or vegetation.

Tsunami sediments and their grain size characteristics

NASA Astrophysics Data System (ADS)

Sulastya Putra, Purna

2018-02-01

Characteristics of tsunami deposits are very complex as the deposition by tsunami is very complex processes. The grain size characteristics of tsunami deposits are simply generalized no matter the local condition in which the deposition took place. The general characteristics are fining upward and landward, poor sorting, and the grain size distribution is not unimodal. Here I review the grain size characteristics of tsunami deposit in various environments: swale, coastal marsh and lagoon/lake. Review results show that although there are similar characters in some environments and cases, but in detail the characteristics in each environment can be distinguished; therefore, the tsunami deposit in each environment has its own characteristic. The local geological and geomorphological condition of the environment may greatly affect the grain size characteristics.

Remnant colloform pyrite at the haile gold deposit, South Carolina: A textural key to genesis

USGS Publications Warehouse

Foley, N.; Ayuso, R.A.; Seal, R.R.

2001-01-01

Auriferous iron sulfide-bearing deposits of the Carolina slate belt have distinctive mineralogical and textural features-traits that provide a basis to construct models of ore deposition. Our identification of paragenetically early types of pyrite, especially remnant colloform, crustiform, and layered growth textures of pyrite containing electrum and pyrrhotite, establishes unequivocally that gold mineralization was coeval with deposition of host rocks and not solely related to Paleozoic tectonic events. Ore horizons at the Haile deposit, South Carolina, contain many remnants of early pyrite: (1) fine-grained cubic pyrite disseminated along bedding; (2) fine- grained spongy, rounded masses of pyrite that may envelop or drape over pyrite cubes; (3) fragments of botryoidally and crustiform layered pyrite, and (4) pyritic infilling of vesicles and pumice. Detailed mineral chemistry by petrography, microprobe, SEM, and EDS analysis of replaced pumice and colloform structures containing both arsenic compositional banding and electrum points to coeval deposition of gold and the volcanic host rocks and, thus, confirms a syngenetic origin for the gold deposits. Early pyrite textures are present in other major deposits of the Carolina slate belt, such as Ridgeway and Barite Hill, and these provide strong evidence for models whereby the sulfide ores formed prior to tectonism. The role of Paleozoic metamorphism was to remobilize and concentrate gold and other minerals in structurally prepared sites. Recognizing the significance of paragenetically early pyrite and gold textures can play an important role in distinguishing sulfide ores that form in volcanic and sedimentary environments from those formed solely by metamorphic processes. Exploration strategies applied to the Carolina slate belt and correlative rocks in the eastern United States in the Avalonian basement will benefit from using syngenetic models for gold mineralization.

Environment as a witness: Selective proliferation of information and emergence of objectivity in a quantum universe

NASA Astrophysics Data System (ADS)

Ollivier, Harold; Poulin, David; Zurek, Wojciech H.

2005-10-01

We study the role of the information deposited in the environment of an open quantum system in the course of the decoherence process. Redundant spreading of information—the fact that some observables of the system can be independently read off from many distinct fragments of the environment—is investigated as the key to effective objectivity, the essential ingredient of classical reality. This focus on the environment as a communication channel through which observers learn about physical systems underscores the importance of quantum Darwinism—selective proliferation of information about “the fittest states” chosen by the dynamics of decoherence at the expense of their superpositions—as redundancy imposes the existence of preferred observables. We demonstrate that the only observables that can leave multiple imprints in the environment are the familiar pointer observables singled out by environment-induced superselection (einselection) for their predictability. Many independent observers monitoring the environment will therefore agree on properties of the system as they can only learn about preferred observables. In this operational sense, the selective spreading of information leads to appearance of an objective classical reality from within the quantum substrate.

Imaging Mercury's Polar Deposits during MESSENGER's Low-altitude Campaign.

PubMed

Chabot, Nancy L; Ernst, Carolyn M; Paige, David A; Nair, Hari; Denevi, Brett W; Blewett, David T; Murchie, Scott L; Deutsch, Ariel N; Head, James W; Solomon, Sean C

2016-09-28

Images obtained during MESSENGER's low-altitude campaign in the final year of the mission provide the highest-spatial-resolution views of Mercury's polar deposits. Images for distinct areas of permanent shadow within 35 north polar craters were successfully captured during the campaign. All of these regions of permanent shadow were found to have low-reflectance surfaces with well-defined boundaries. Additionally, brightness variations across the deposits correlate with variations in the biannual maximum surface temperature across the permanently shadowed regions, supporting the conclusion that multiple volatile organic compounds are contained in Mercury's polar deposits, in addition to water ice. A recent large impact event or ongoing bombardment by micrometeoroids could deliver water as well as many volatile organic compounds to Mercury. Either scenario is consistent with the distinctive reflectance properties and well-defined boundaries of Mercury's polar deposits and the presence of volatiles in all available cold traps.

Can barrier islands survive sea level rise? Tidal inlets versus storm overwash

NASA Astrophysics Data System (ADS)

Nienhuis, J.; Lorenzo-Trueba, J.

2017-12-01

Barrier island response to sea level rise depends on their ability to transgress and move sediment to the back barrier, either through flood-tidal delta deposition or via storm overwash. Our understanding of these processes over decadal to centennial timescales, however, is limited and poorly constrained. We have developed a new barrier inlet environment (BRIE) model to better understand the interplay between tidal dynamics, overwash fluxes, and sea-level rise on barrier evolution. The BRIE model combines existing overwash and shoreface formulations [Lorenzo-Trueba and Ashton, 2014] with alongshore sediment transport, inlet stability [Escoffier, 1940], inlet migration and flood-tidal delta deposition [Nienhuis and Ashton, 2016]. Within BRIE, inlets can open, close, migrate, merge with other inlets, and build flood-tidal delta deposits. The model accounts for feedbacks between overwash and inlets through their mutual dependence on barrier geometry. Model results suggest that when flood-tidal delta deposition is sufficiently large, barriers require less storm overwash to transgress and aggrade during sea level rise. In particular in micro-tidal environments with asymmetric wave climates and high alongshore sediment transport, tidal inlets are effective in depositing flood-tidal deltas and constitute the majority of the transgressive sediment flux. Additionally, we show that artificial inlet stabilization (via jetty construction or maintenance dredging) can make barrier islands more vulnerable to sea level rise. Escoffier, F. F. (1940), The Stability of Tidal Inlets, Shore and Beach, 8(4), 114-115. Lorenzo-Trueba, J., and A. D. Ashton (2014), Rollover, drowning, and discontinuous retreat: Distinct modes of barrier response to sea-level rise arising from a simple morphodynamic model, J. Geophys. Res. Earth Surf., 119(4), 779-801, doi:10.1002/2013JF002941. Nienhuis, J. H., and A. D. Ashton (2016), Mechanics and rates of tidal inlet migration: Modeling and application to natural examples, J. Geophys. Res. Earth Surf., 121(11), 2118-2139, doi:10.1002/2016JF004035.

Universal Coatings Based on Zwitterionic-Dopamine Copolymer Microgels.

PubMed

Vatankhah-Varnosfaderani, Mohammad; Hu, Xiaobo; Li, Qiaoxi; Adelnia, Hossein; Ina, Maria; Sheiko, Sergei S

2018-06-05

Multifunctional coatings that adhere to chemically distinct substrates are vital in many industries, including automotive, aerospace, shipbuilding, construction, petrochemical, biomedical, and pharmaceutical. We design well-defined, nearly monodisperse microgels that integrate hydrophobic dopamine methacrylamide monomers and hydrophilic zwitterionic monomers. The dopamine functionalities operate as both intraparticle cross-linkers and interfacial binders, respectively providing mechanical strength of the coatings and their strong adhesion to different substrates. In tandem, the zwitterionic moieties enable surface hydration to empower antifouling and antifogging properties. Drop-casting of microgel suspensions in ambient as well as humid environments facilitates rapid film formation and tunable roughness through regulation of cross-linking density and deposition conditions.

Evaluation of stream sediments in areas of known mineralization, San Jose and Talamanca Quadrangles, Costa Rica: An orientation survey

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arauz, A.J.

1986-12-01

Costa Rica's compressional island arc-type tectonic setting and considerable geologic diversity hold great promise for future discovery of economic metallic deposits. The study constitutes an orientation investigation of stream sediment sampling techniques to establish optimum survey specifications for the regional geochemical survey coverage of the country. The study was conducted in two separate areas of known mineralization which represent distinctive tropical environments and different metallogenic provinces within Costa Rica: (1) the Esparza Area, which contains the Santa Clara Gold Mine, the largest in the country, and (2) the San Isidro Area, which contains a major copper prospect.

Organic Chemostratigraphic Markers Characteristic of the (Informally Designated) Anthropocene Epoch

NASA Astrophysics Data System (ADS)

Kruge, M. A.

2008-12-01

Recognizing the tremendous collective impact of humans on the environment in the industrial age, the proposed designation of the current time period as the Anthropocene Epoch has considerable merit. One of the signature activities during this time continues to be the intensive extraction, processing, and combustion of fossil fuels. While fossil fuels themselves are naturally-occurring, they are most often millions of years old and associated with deeply buried strata. They may be found at the surface, for example, as natural oil seeps or coal seam outcrops, but these are relatively rare occurrences. Fossil fuels and their myriad by- products become the source of distinctive organic chemostratigraphic marker compounds for the Anthropocene when they occur out of their original geological context, i.e., as widespread contaminants in sediments and soils. These persistent compounds have high long-term preservation potential, particularly when deposited under low oxygen conditions. Fossil fuels can occur as environmental contaminants in raw form (e.g., crude petroleum spilled during transport) or as manufactured products (e.g., diesel oil from a leaking storage facility, coal tar from a manufactured gas plant, plastic waste in a landfill, pesticides from petroleum feedstock in agricultural soils). Distinctive assemblages of hydrocarbon marker compounds including acyclic isoprenoids, hopanes, and steranes can be readily detected by gas chromatography/mass spectrometric analysis of surface sediments and soils. Polycyclic aromatic hydrocarbons (PAHs), along with sulfur-, oxygen-, and nitrogen-containing aromatic compounds, are also characteristic of fossil fuels and are readily detectable as well. More widespread is the airfall deposition of fossil fuel combustion products from vehicular, domestic and industrial sources. These occur in higher concentrations in large urban centers, but are also detected in remote areas. Parent (nonmethylated) PAHs such as phenanthrene, fluoranthene and pyrene are the most abundant organic marker compounds in these combustion-derived deposits, distinguishable in their types and proportions from the combustion products of natural vegetation fires. The occurrence of specific fossil fuel combustion-derived PAH assemblages serves as a stratigraphic signature for Anthropocene deposits.

Giant landslide deposits in northwest Argentina

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fauque, L.; Strecker, M.R.; Bloom, A.L.

1985-01-01

Giant Quaternary landslide deposits occur along mountain fronts in the structural transition zone between the high-angle reverse-fault-bounded Sierras Pampeanas and the low-angle thrust belt of the Sierras Subandinas. There are two modes of occurrence: (1) chaotic masses without distinct geometry, and (2) masses with distinct lobate geometry similar to glacial moraines. Type (1) deposits occur where the moving rock mass followed a narrow valley and blocked the drainage. Many of these caused subsequent formation of lakes and changed the sedimentation processes on pediments at the mountain fronts. In type (2) deposits, lateral and frontal ridges are up to 10 mmore » higher than the interior parts; in some places pressure ridges within the lobes are well preserved. Type (2) deposits show reverse grading and were deposited on relatively smooth pediments or alluvial fans. The lobate geometry strongly suggests that type (2) deposits are a product of flowage and are debris stream or sturzstrom deposits (sense of Heim, 1932 and Hsu, 1975). All investigated deposits occur in areas of demonstrated Quaternary faulting and are interpreted as the result of tectonic movements, although structural inhomogeneities in the source area may have been a significant factor for some of the landslides. No datable materials have yet been found associated with the deposits.« less

22 CFR 92.49 - “Deposition” defined.

Code of Federal Regulations, 2010 CFR

2010-04-01

... Foreign Relations DEPARTMENT OF STATE LEGAL AND RELATED SERVICES NOTARIAL AND RELATED SERVICES Depositions and Letters Rogatory § 92.49 “Deposition” defined. A deposition is the testimony of a witness taken in... interrogatories, oral or written. (For the distinction between a deposition and an affidavit see § 92.22.) ...

22 CFR 92.49 - “Deposition” defined.

Code of Federal Regulations, 2011 CFR

2011-04-01

... Foreign Relations DEPARTMENT OF STATE LEGAL AND RELATED SERVICES NOTARIAL AND RELATED SERVICES Depositions and Letters Rogatory § 92.49 “Deposition” defined. A deposition is the testimony of a witness taken in... interrogatories, oral or written. (For the distinction between a deposition and an affidavit see § 92.22.) ...

Environmental Transitions Recorded by Fluvial Fan Stratigraphy at Dingo Gap and Moonlight Valley, Gale Crater, Mars

NASA Astrophysics Data System (ADS)

Edgar, L. A.; Gupta, S.; Rubin, D. M.; Schieber, J.; Stack, K.; Lewis, K. W.

2016-12-01

The Mars Science Laboratory (MSL) Curiosity rover investigated a number of sedimentary outcrops across Aeolis Palus. Observations of conglomerates, cross-bedded sandstones, and mudstones suggest that fluvial and lacustrine environments were common. Outcrops that expose cross-sections are particularly helpful for identifying stratigraphic relationships and changes through time. In the vicinity of an outcrop informally named Dingo Gap, the drive strategy shifted from driving on the topographic high areas to the topographic low areas, which resulted in a unique vantage point to observe stratigraphy in cross-section. During Sols 513-541, Curiosity investigated 4 m of stratigraphy exposed at Dingo Gap and Moonlight Valley. The valley walls reveal five distinct sedimentary facies, including 1) a fine-grained evenly laminated facies interpreted as upper plane bed stratification, 2) ripple and dune cross-stratified sandstone facies, interpreted to represent the southward migration of subaqueous bedforms, 3) fully preserved bedform sandstone facies, formed during high rates of deposition, 4) planar-bedded granule-rich sandstone facies, interpreted as sheet flood deposits, and 5) a weakly stratified, poorly-sorted conglomerate facies, interpreted to represent rapid deposition from a high-energy fluvial flow. The conglomerate facies is unlike other conglomerates observed thus far in the mission, on the basis of both texture and chemistry. Analysis of conglomerates reveal that they occur as distinct channel bodies, incised into cross-stratified sandstones. This coarsening upward signature is interpreted to record a prograding fan succession. Channel bodies appear to be time-equivalent, which suggests a major change in the system, likely associated with a drop in base level. The unique viewing geometry offered by Dingo Gap and Moonlight Valley makes it possible to observe these environmental changes.

Characterization of petroleum reservoirs in the Eocene Green River Formation, Central Uinta Basin, Utah

USGS Publications Warehouse

Morgan, C.D.; Bereskin, S.R.

2003-01-01

The oil-productive Eocene Green River Formation in the central Uinta Basin of northeastern Utah is divided into five distinct intervals. In stratigraphically ascending order these are: 1) Uteland Butte, 2) Castle Peak, 3) Travis, 4) Monument Butte, and 5) Beluga. The reservoir in the Uteland Butte interval is mainly lacustrine limestone with rare bar sandstone beds, whereas the reservoirs in the other four intervals are mainly channel and lacustrine sandstone beds. The changing depositional environments of Paleocene-Eocene Lake Uinta controlled the characteristics of each interval and the reservoir rock contained within. The Uteland Butte consists of carbonate and rare, thin, shallow-lacustrine sandstone bars deposited during the initial rise of the lake. The Castle Peak interval was deposited during a time of numerous and rapid lake-level fluctuations, which developed a simple drainage pattern across the exposed shallow and gentle shelf with each fall and rise cycle. The Travis interval records a time of active tectonism that created a steeper slope and a pronounced shelf break where thick cut-and-fill valleys developed during lake-level falls and rises. The Monument Butte interval represents a return to a gentle, shallow shelf where channel deposits are stacked in a lowstand delta plain and amalgamated into the most extensive reservoir in the central Uinta Basin. The Beluga interval represents a time of major lake expansion with fewer, less pronounced lake-level falls, resulting in isolated single-storied channel and shallow-bar sandstone deposits.

Shaler: in situ analysis of a fluvial sedimentary deposit on Mars

DOE Office of Scientific and Technical Information (OSTI.GOV)

Edgar, Lauren A.; Gupta, Sanjeev; Rubin, David M.

This article characterizes the detailed sedimentology of a fluvial sandbody on Mars for the first time and interprets its depositional processes and palaeoenvironmental setting. Despite numerous orbital observations of fluvial landforms on the surface of Mars, ground-based characterization of the sedimentology of such fluvial deposits has not previously been possible. Results from the NASA Mars Science Laboratory Curiosity rover provide an opportunity to reconstruct at fine scale the sedimentary architecture and palaeomorphology of a fluvial environment on Mars. This work describes the grain size, texture and sedimentary facies of the Shaler outcrop, reconstructs the bedding architecture, and analyses cross-stratification tomore » determine palaeocurrents. On the basis of bedset geometry and inclination, grain-size distribution and bedform migration direction, this study concludes that the Shaler outcrop probably records the accretion of a fluvial barform. The majority of the outcrop consists of large-scale trough cross-bedding of coarse sand and granules. Palaeocurrent analyses and bedform reconstruction indicate that the beds were deposited by bedforms that migrated towards the north-east, across the surface of a bar that migrated south-east. Stacked cosets of dune cross-bedding suggest aggradation of multiple bedforms, which provides evidence for short periods of sustained flow during Shaler deposition. However, local evidence for aeolian reworking and the presence of potential desiccation cracks within the outcrop suggest that fluvial deposition may have been intermittent. The uppermost strata at Shaler are distinct in terms of texture and chemistry and are inferred to record deposition from a different sediment dispersal system with a contrasting provenance. The outcrop as a whole is a testament to the availability of liquid water on the surface of Mars in its early history.« less

Shaler: in situ analysis of a fluvial sedimentary deposit on Mars

USGS Publications Warehouse

Edgar, Lauren; Gupta, Sanjeev; Rubin, David M.; Lewis, Kevin W.; Kocurek, Gary A.; Anderson, Ryan; Bell, James F.; Dromart, Gilles; Edgett, Kenneth S.; Grotzinger, John P.; Hardgrove, Craig; Kah, Linda C.; LeVeille, Richard A.; Malin, Michael C.; Mangold, Nicholas; Milliken, Ralph E.; Minitti, Michelle; Palucis, Marisa C.; Rice, Melissa; Rowland, Scott K.; Schieber, Juergen; Stack, Kathryn M.; Sumner, Dawn Y.; Wiens, Roger C.; Williams, Rebecca M.E.; Williams, Amy J.

2018-01-01

This paper characterizes the detailed sedimentology of a fluvial sandbody on Mars for the first time, and interprets its depositional processes and palaeoenvironmental setting. Despite numerous orbital observations of fluvial landforms on the surface of Mars, ground-based characterization of the sedimentology of such fluvial deposits has not previously been possible. Results from the NASA Mars Science Laboratory Curiosity rover provide an opportunity to reconstruct at fine scale the sedimentary architecture and palaeomorphology of a fluvial environment on Mars. This work describes the grain size, texture, and sedimentary facies of the Shaler outcrop, reconstructs the bedding architecture, and analyses cross-stratification to determine palaeocurrents. On the basis of bedset geometry and inclination, grain-size distribution, and bedform migration direction, this study concludes that the Shaler outcrop likely records the accretion of a fluvial barform. The majority of the outcrop consists of large-scale trough cross-bedding of coarse sand and granules. Palaeocurrent analyses and bedform reconstruction indicate that the beds were deposited by bedforms that migrated towards the northeast, across the surface of a bar that migrated southeast. Stacked cosets of dune cross-bedding suggest aggradation of multiple bedforms, which provides evidence for short periods of sustained flow during Shaler deposition. However, local evidence for aeolian reworking and the presence of potential desiccation cracks within the outcrop suggests that fluvial deposition may have been intermittent. The uppermost strata at Shaler are distinct in terms of texture and chemistry, and are inferred to record deposition from a different sediment dispersal system with a contrasting provenance. The outcrop as a whole is a testament to the availability of liquid water on the surface of Mars in its early history.

Shaler: in situ analysis of a fluvial sedimentary deposit on Mars

DOE PAGES

Edgar, Lauren A.; Gupta, Sanjeev; Rubin, David M.; ...

2017-03-09

This article characterizes the detailed sedimentology of a fluvial sandbody on Mars for the first time and interprets its depositional processes and palaeoenvironmental setting. Despite numerous orbital observations of fluvial landforms on the surface of Mars, ground-based characterization of the sedimentology of such fluvial deposits has not previously been possible. Results from the NASA Mars Science Laboratory Curiosity rover provide an opportunity to reconstruct at fine scale the sedimentary architecture and palaeomorphology of a fluvial environment on Mars. This work describes the grain size, texture and sedimentary facies of the Shaler outcrop, reconstructs the bedding architecture, and analyses cross-stratification tomore » determine palaeocurrents. On the basis of bedset geometry and inclination, grain-size distribution and bedform migration direction, this study concludes that the Shaler outcrop probably records the accretion of a fluvial barform. The majority of the outcrop consists of large-scale trough cross-bedding of coarse sand and granules. Palaeocurrent analyses and bedform reconstruction indicate that the beds were deposited by bedforms that migrated towards the north-east, across the surface of a bar that migrated south-east. Stacked cosets of dune cross-bedding suggest aggradation of multiple bedforms, which provides evidence for short periods of sustained flow during Shaler deposition. However, local evidence for aeolian reworking and the presence of potential desiccation cracks within the outcrop suggest that fluvial deposition may have been intermittent. The uppermost strata at Shaler are distinct in terms of texture and chemistry and are inferred to record deposition from a different sediment dispersal system with a contrasting provenance. The outcrop as a whole is a testament to the availability of liquid water on the surface of Mars in its early history.« less

Tectonostratigraphy and depositional history of the Neoproterozoic volcano-sedimentary sequences in Kid area, southeastern Sinai, Egypt: Implications for intra-arc to foreland basin in the northern Arabian-Nubian Shield

NASA Astrophysics Data System (ADS)

Khalaf, E. A.; Obeid, M. A.

2013-09-01

This paper presents a stratigraphic and sedimentary study of Neoproterozoic successions of the South Sinai, at the northernmost segment of the Arabian-Nubian Shield (ANS), including the Kid complex. This complex is composed predominantly of thick volcano-sedimentary successions representing different depositional and tectonic environments, followed by four deformational phases including folding and brittle faults (D1-D4). The whole Kid area is divisible from north to south into the lower, middle, and upper rock sequences. The higher metamorphic grade and extensive deformational styles of the lower sequence distinguishes them from the middle and upper sequences. Principal lithofacies in the lower sequence include thrust-imbricated tectonic slice of metasediments and metavolcanics, whereas the middle and upper sequences are made up of clastic sediments, intermediate-felsic lavas, volcaniclastics, and dike swarms. Two distinct Paleo- depositional environments are observed: deep-marine and alluvial fan regime. The former occurred mainly during the lower sequence, whereas the latter developed during the other two sequences. These alternations of depositional conditions in the volcano-sedimentary deposits suggest that the Kid area may have formed under a transitional climate regime fluctuating gradually from warm and dry to warm and humid conditions. Geochemical and petrographical data, in conjunction with field relationships, suggest that the investigated volcano-sedimentary rocks were built from detritus derived from a wide range of sources, ranging from Paleoproterozoic to Neoproterozoic continental crust. Deposition within the ancient Kid basin reflects a complete basin cycle from rifting and passive margin development, to intra-arc and foreland basin development and, finally, basin closure. The early phase of basin evolution is similar to various basins in the Taupo volcanics, whereas the later phases are similar to the Cordilleran-type foreland basin. The progressive change in lithofacies from marine intra-arc basin to continental molasses foreland basin and from compression to extension setting respectively, imply that the source area became peneplained, where the Kid basin became stabilized as sedimentation progressed following uplift. The scenario proposed of the study area supports the role of volcanic and tectonic events in architecting the facies and stratigraphic development.

Mimosa caesalpiniifolia rhizobial isolates from different origins of the Brazilian Northeast.

PubMed

Martins, Paulo Geovani Silva; Junior, Mario Andrade Lira; Fracetto, Giselle Gomes Monteiro; da Silva, Maria Luiza Ribeiro Bastos; Vincentin, Rayssa Pereira; de Lyra, Maria do Carmo Catanho Pereira

2015-04-01

Biological nitrogen fixation from the legume-rhizobia symbiosis is one of the main sources of fixed nitrogen on land environments. Diazotrophic bacteria taxonomy has been substantially modified by the joint use of phenotypic, physiological and molecular aspects. Among these molecular tools, sequencing and genotyping of genomic regions such as 16S rDNA and repetitive conserved DNA regions have boosted the accuracy of species identification. This research is a phylogenetic study of diazotrophic bacteria from sabiá (Mimosa caesalpiniifolia Benth.), inoculated with soils from five municipalities of the Brazilian Northeast. After bacterial isolation and morphophysiological characterization, genotyping was performed using REP, ERIC and BOX oligonucleotides and 16S rDNA sequencing for genetic diversity identification. A 1.5b Kb fragment of the 16S rDNA was amplified from each isolate. Morphophysiological characterization of the 47 isolates created a dendrogram, where isolate PE-GR02 formed a monophyletic branch. The fingerprinting conducted with BOX, ERIC and REP shows distinct patterns, and their compilation created a dendrogram with diverse groups and, after blasting in GenBank, resulted in genetic identities ranging from 77 to 99 % with Burkholderia strains. The 16S rDNA phylogenetic tree constructed with these isolates and GenBank deposits of strains recommended for inoculant production confirm these isolates are distinct from the previously deposited strains, whereas isolates PE-CR02, PE-CR4, PE-CR07, PE-CR09 and PE-GE06 were the most distinct within the group. Morphophysiological characterization and BOX, ERIC and REP compilation enhanced the discrimination of the isolates, and the 16S rDNA sequences compared with GenBank confirmed the preference of Mimosa for Burkholderia diazotrophic bacteria.

Evidences of melting of terrestrial sediments and paleoenvironment changes during the Younger Dryas in tectonic lacustrine basins of Transmexican Volcanic Belt, Mexico.

NASA Astrophysics Data System (ADS)

Israde-Alcantara, I.

2017-12-01

It is well known in the sedimentary record of several parts of the world that during the Younger Dryas interval (YD) ocurred an abrupt environmental change between 12,900 and 11,700 cal yr BP (10,900 to 10,000 14C BP). In the lacustrine basins this changes are often preserved and in some Mexican lakes this is a distinctive stratigraphic marker for the YD. We analized the proxies of this event in cores of two lakes (Chapala, Cuitzeo) and three trenches of ex-lakes (Acambay,Texcoco and El Cedral). Deposits consist of fine detrital material with often Pleistocene fossil vertebrate assemblages. At the Chapala, Cuitzeo, Acambay, and Tocuila lacustrine environments are found in association with a distinctive dark organic layer showing sharp changes in the diatom, pollen, mineralogical and geochemical record. Includes also microscopic magnetic, Fe-rich spherules, silica melted droplets with aerodynamic shapes (tektites), followed by large amounts of charcoal, and sometimes nanodiamonds (Cuitzeo), that were deposited at the onset of the YD or in the limit Pleistocene-Holocene. These unusual materials are buried more than 2.50 meters and were not observed above or below the Younger Dryas sediments at these sites. The geochemistry of the microspherules indicates that they are not volcanic, anthropogenic or authigenic origin. A very distinctive feature is the shape of the spherules, ovoid, polygonal, filigreed or dendritic indicating melting and quenching infering that are product of an impact event. Their morphologies includes hollow shells caused by de-gassing of elements at very high temperatures causing a flattened side with a "skirt" structure by a high-velocity collision.Our results are consistent with the Firestone hypothesis.

Early Jurassic hydrothermal vent community from the Franciscan Complex, San Rafael Mountains, California

NASA Astrophysics Data System (ADS)

Little, Crispin T. S.; Herrington, Richard J.; Haymon, Rachel M.; Danelian, Taniel

1999-02-01

The Figueroa massive sulfide deposit, located in Franciscan Complex rocks in the San Rafael Mountains of California, preserves the only known Jurassic hydrothermal vent fossils. The Figueroa fossil assemblage is specimen rich but of low diversity and comprises, in order of decreasing abundance, vestimentiferan worm tubes, the rhynchonellid brachiopod Anarhynchia cf. gabbi and a species of ?nododelphinulid gastropod. The Figueroa fossil organisms lived at a deep-water, high-temperature vent site located on a mid-ocean ridge or seamount at an equatorial latitude. The fossil vent site was then translated northwestward by the motion of the Farallon plate and was subsequently accreted to its present location. An iron-silica exhalite bed, the probable lateral equivalent of the Figueroa deposit, contains abundant filamentous microfossils with two distinct morphologies and probably represents a lower-temperature, diffuse-flow environment. The Figueroa fossil community was subject to the same environmental conditions as modern vent communities, but it is unique among modern and other fossil vent communities in having rhynchonellid brachiopods.

A 3400 year paleolimnological record of prehispanic human–environment interactions in the Holmul region of the southern Maya lowlands

USGS Publications Warehouse

Wahl, David B.; Estrada-Belli, Francisco; Anderson, Lysanna

2015-01-01

The timing, magnitude and drivers of late Holocene environmental change in the Holmul region of the southern Maya lowlands are examined by combining paleoenvironmental and archeological data. Environmental proxy analyses on a ~ 3350 cal yr lacustrine sediment record include pollen, charcoal, loss on ignition, magnetic suscep- tibility, and elemental geochemistry. Archeological evidence is derived from extensive settlement surveys conducted near the study site. Results indicate nearby settlement and agricultural activity taking place in an environment characterized by open forest from around 3350 to 950 cal yr BP. The fire history shows a dramatic increase in burning during the Classic period, possibly reflecting changing agricultural strategies. A distinct band of carbonate deposited from 1270 to 1040 cal yr BP suggests decreased hydrologic input associated with drier conditions. Abrupt changes in proxy data around 940 cal yr BP indicate a cessation of human disturbance and local abandonment of the area.

Geochemistry of environmentally sensitive trace elements in Permian coals from the Huainan coalfield, Anhui, China

USGS Publications Warehouse

Chen, J.; Liu, Gaisheng; Jiang, M.; Chou, C.-L.; Li, H.; Wu, B.; Zheng, Lingyun; Jiang, D.

2011-01-01

To study the geochemical characteristics of 11 environmentally sensitive trace elements in the coals of the Permian Period from the Huainan coalfield, Anhui province, China, borehole samples of 336 coals, two partings, and four roof and floor mudstones were collected from mineable coal seams. Major elements and selected trace elements were determined by inductively coupled plasma optical emission spectrometry (ICP-OES), inductively coupled plasma mass spectrometry (ICP-MS), and hydride generation atomic absorption spectrometry (HAAS). The depositional environment, abundances, distribution, and modes of occurrence of trace elements were investigated. Results show that clay and carbonate minerals are the principal inorganic constituents in the coals. A lower deltaic plain, where fluvial channel systems developed successively, was the likely depositional environment of the Permian coals in the Huainan coalfield. All major elements have wider variation ranges than those of Chinese coals except for Mg and Fe. The contents of Cr, Co, Ni, and Se are higher than their averages for Chinese coals and world coals. Vertical variations of trace elements in different formations are not significant except for B and Ba. Certain roof and partings are distinctly higher in trace elements than underlying coal bench samples. The modes of occurrence of trace elements vary in different coal seams as a result of different coal-forming environments. Vanadium, Cr, and Th are associated with aluminosilicate minerals, Ba with carbonate minerals, and Cu, Zn, As, Se, and Pb mainly with sulfide minerals. ?? 2011 Elsevier B.V.

Deposition of an Ultraflat Graphene Oxide Nanosheet on Atomically Flat Substrates

NASA Astrophysics Data System (ADS)

Khan, M. Z. H.; Shahed, S. M. F.; Yuta, N.; Komeda, T.

2017-07-01

In this study, graphene oxide (GO) sheets produced in the form of stable aqueous dispersions were deposited on Au (111), freshly cleaved mica, and highly oriented pyrolytic graphite (HOPG) substrates. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) were used to study the presence and distinct contact of GO sheets on the substrates. It was revealed from the topography images that high-quality ultraflat GO monolayer sheets formed on the substrates without distinct cracking/wrinkling or folding. GO sheets with apparent height variation observed by microscopy also indicate ultraflat deposition with clear underlying steps. It was observed that ultrasonication and centrifuge steps prior to deposition were very effective for getting oxidation debris (OD)-free ultraflat single monolayer GO nanosheets onto substrates and that the process depends on the concentration of supplied GO solutions.

The transitional depositional environment and sequence stratigraphy of Chasma Boreale

NASA Astrophysics Data System (ADS)

Brothers, S. C.; Kocurek, G.

2018-07-01

The depositional system within Chasma Boreale is unique in that it contains active aeolian environments, expressed as dune fields, and active cryosphere environments, present as layered ice deposits, as well as environments that transition between these. This work presents a new analysis of the Chasma Boreale sediment system that creates an interpretative framework addressing: (a) controls on the balance between aeolian and cryospheric processes in the modern depositional system, (b) the stratigraphic architecture of related sedimentary deposits, and (c) processes of sediment accumulation and preservation. Images from Context Camera (CTX; 6 m/pixel) are used to classify and map sedimentary environments, surfaces, and deposits on the reentrant floor, to refine the established geologic map of the reentrant, and to infer the stratigraphic record of the accumulation from Chasma Boreale's depositional system. A spectrum of sedimentary environments occurring between those dominated by aeolian and by cryospheric processes are identified. Through time, the boundaries of these sedimentary environments have shifted, resulting in complex lateral changes in the configuration of sedimentary environments on the reentrant's floor. Vertically, the stratigraphic record is characterized by the punctuation of sandy aeolian deposits by icy surfaces that indicate episodes of ice growth that preserve underlying deposits, resulting in accumulation. Stabilized icy surfaces occur at multiple vertical (temporal) scales and lateral extents, suggesting the influence of both regional climate change due to allogenic forcing, as well as autogenic dynamics within the transitional system. These observations demonstrate that the Chasma Boreale accumulation can be interpreted in an aeolian sequence stratigraphic framework. This work contributes the first detailed description of the processes forming polar aeolian sequences, with an emphasis on the competing and complementary dynamics between aeolian and cryospheric systems.

Distribution of beach litter along the coastline of Cádiz, Spain.

PubMed

Williams, Allan Thomas; Randerson, Peter; Di Giacomo, Carlo; Anfuso, Giorgio; Macias, Ana; Perales, José Antonio

2016-06-15

A total of 59 categories of litter items were found at 20 beaches (13 mechanically cleaned, 7 non-cleaned) in the Cádiz tourist environment, Spain. Cluster Analysis and Principal Components Analysis were used to highlight similarities and contrasts between sites and/or associations between litter categories. Multivariate analyses separated beaches according to the total numbers of litter items present. Non-cleaned sites showed a variety of litter category abundance with distinct origins and abundant, ubiquitous items (plastic and glass fragments). Of the 7 non-cleaned beaches (49 litter categories) river-mouth sites were distinct due with high numbers of litter items. The sheltered inner part of Cádiz Bay beaches had a wide range of litter type. Many sites were associated with locally deposited recreational litter categories; while industrial/commercial/fishing categories were abundant only at a few sites, indicating items transported onto the shore from the Guadalete river. Copyright © 2016 Elsevier Ltd. All rights reserved.

Middle to Late Pleistocene multi-proxy record of environmental response to climate change from the Vienna Basin, Central Europe (Austria)

NASA Astrophysics Data System (ADS)

Salcher, Bernhard C.; Frank-Fellner, Christa; Lomax, Johanna; Preusser, Frank; Ottner, Franz; Scholger, Robert; Wagreich, Michael

2017-10-01

Tectonic basins can represent valuable archives of the environmental history. Presented here are the stratigraphy and multi-proxy analyses of two adjacent alluvial fans in the Quaternary active parts of the Vienna Basin, situated at the interface of the Atlantic, European continental and Mediterranean climate. Deposits comprise a sequence of coarse-grained fluvial deposits intercalated by laterally extensive horizons of pedogenically altered fine sediments. To establish palaeoenvironmental reconstructions, fine-grained sequences from a drill core and outcrop data were analysed according to its malacofauna, palaeopedology, susceptibility and sedimentology. The chronological framework is provided by 38 luminescence ages and supported by geomagnetic polarity investigations. Distinct warm periods each associated with a geomagnetic excursion, are recorded in three pedocomplexes formed during the Last Interglacial and two earlier interglacial periods, indicted to correlate with Marine Isotope Stage (MIS) 9 and MIS 11, respectively. Environmental conditions during the early last glacial period (MIS 5, c. 100-70 ka) are reconstructed from mollusc-shell rich overbank fines deposited along a former channel belt, covered by massive sheetflood deposits during MIS 2. Analysed warm phases suggest strong variations in humidity, ranging from steppe to forest dominated environments. The study presents one of the few numerically dated Middle Pleistocene multi-proxy records and one of the most comprehensive malacological datasets covering the early phases of last glacial period of continental Europe.

Highly flexible and electroforming free resistive switching behavior of tungsten disulfide flakes fabricated through advanced printing technology

NASA Astrophysics Data System (ADS)

Muqeet Rehman, Muhammad; Uddin Siddiqui, Ghayas; Doh, Yang Hoi; Choi, Kyung Hyun

2017-09-01

Tungsten disulfide (WS2) is a transition metal dichalcogenide that differs from other 2D materials such as graphene owing to its distinctive semiconducting nature and tunable band gap. In this study, we have reported the structural, electrical, physical, and mechanical properties of exfoliated WS2 flakes and used them as the functional layer of a rewritable bipolar memory device. We demonstrate this concept by sandwiching few-layered WS2 flakes between two silver (Ag) electrodes on a flexible and transparent PET substrate. The entire device fabrication was carried out through all-printing technology such as reverse offset printing for patterning bottom electrodes, electrohydrodynamic (EHD) atomization for depositing functional thin film and EHD patterning for depositing the top electrode respectively. The memory device was further encapsulated with an atomically thin layer of aluminum oxide (Al2O3), deposited through a spatial atmospheric atomic layer deposition system to protect it against a humid environment. Remarkable resistive switching results were obtained, such as nonvolatile bipolar behavior, a high switching ratio (∼103), a long retention time (∼105 s), high endurance (1500 voltage sweeps), a low operating voltage (∼2 V), low current compliance (50 μA), mechanical robustness (1500 cycles) and unique repeatability at ambient conditions. Ag/WS2/Ag-based memory devices offer a new possibility for integration in flexible electronic devices.

Late Pleistocene sediments and fossils near the mouth of Mad River, Humboldt County, California: Facies analysis, sequence development, and possible age correlation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harvey, E.W.

Study of late Pleistocene-age sediments near the mouth of the Mad River revealed a sequence of nearshore marine and shallow bay deposits. This sequence, bounded by unconformities, is informally named the Mouth of Mad unit. The Mouth of mad unit can be divided into four distinct depositional facies at the study site. The lowest facies are the Nearshore Sand and Estuarine Mud, which lie unconformably on a paleosol. The sand facies grades upward into a high-energy, interbedded Nearshore Sand and Gravel facies containing storm and rip-channel deposits. Above the sand and gravel is a Strand-Plain Sand facies. This sand ismore » overlain by a laterally variable sequence of shell-rich Bay facies. The bay deposits can be further divided into five subfacies: (1) a Bioturbated Sand; (2) a Lower Tidal Flat Mud; (3) a Mixed Sand and Mud; (4) an oyster-rich Bay Mud; and (5) an Upper Tidal Flat Mud. The bay sequence is overlain unconformably by younger late Pleistocene-age marine terrace deposits. The depositional environments represented by these facies progress from a shoreline estuary to nearshore deposits, above storm wave base, and slowly back to shoreline and finally shallow bay conditions. The Mouth of Mad unit represents a transgressive-regressive sequence, involving the development of a protective spit. The uppermost mud within the Mouth of Mad unit has been dated, using thermoluminescence age estimation, at 176 [+-] 33 ka, placing it in the late Pleistocene. The Mouth of Mad unit appears to be younger than the fossiliferous deposits at Elk Head, Crannell Junction, Trinidad Head, Moonstone Beach, and the Falor Formation near Maple Creek, and possibly time equivalent with gravel deposits exposed at the western end of School Road in McKinleyville.« less

Geochemistry of host rocks in the Howards Pass district, Yukon-Northwest Territories, Canada: implications for sedimentary environments of Zn-Pb and phosphate mineralization

USGS Publications Warehouse

Slack, John F.; Falck, Hendrik; Kelley, Karen D.; Xue, Gabriel G.

2017-01-01

Detailed lithogeochemical data are reported here on early Paleozoic sedimentary rocks that host the large Howards Pass stratiform Zn-Pb deposits in Yukon-Northwest Territories. Redox-sensitive trace elements (Mo, Re, V, U) and Ce anomalies in members of the Duo Lake Formation record significant environmental changes. During the deposition of lower footwall units (Pyritic siliceous and Calcareous mudstone members), bottom waters were anoxic and sulphidic, respectively; these members formed in a marginal basin that may have become increasingly restricted with time. Relative to lower members, a major environmental change is proposed for deposition of the overlying Lower cherty mudstone member, which contains phosphorite beds up to ∼0.8 m thick in the upper part, near the base of the Zn-Pb deposits. The presence of these beds, together with models for modern phosphorite formation, suggests P input from an upwelling system and phosphorite deposition in an upper slope or outer shelf setting. The overlying Active mudstone member contains stratabound to stratiform Zn-Pb deposits within black mudstone and gray calcareous mudstone. Data for unmineralized black mudstone in this member indicate deposition under diverse redox conditions from suboxic to sulphidic. Especially distinctive in this member are uniformly low ratios of light to heavy rare earth elements that are unique within the Duo Lake Formation, attributed here to the dissolution of sedimentary apatite by downward-percolating acidic metalliferous brines. Strata that overlie the Active member (Upper siliceous mudstone member) consist mainly of black mudstone with thin (0.5–1.5 cm) laminae of fine-grained apatite, recording continued deposition on an upper slope or outer shelf under predominantly suboxic bottom waters. Results of this study suggest that exploration for similar stratiform sediment-hosted Zn-Pb deposits should include the outer parts of ancient continental margins, especially at and near stratigraphic transitions from marginal basin facies to overlying slope or shelf facies.

Calorimetric evidence for two distinct molecular packing arrangements in stable glasses of indomethacin.

PubMed

Kearns, Kenneth L; Swallen, Stephen F; Ediger, M D; Sun, Ye; Yu, Lian

2009-02-12

Indomethacin glasses of varying stabilities were prepared by physical vapor deposition onto substrates at 265 K. Enthalpy relaxation and the mobility onset temperature were assessed with differential scanning calorimetry (DSC). Quasi-isothermal temperature-modulated DSC was used to measure the reversing heat capacity during annealing above the glass transition temperature Tg. At deposition rates near 8 A/s, scanning DSC shows two enthalpy relaxation peaks and quasi-isothermal DSC shows a two-step change in the reversing heat capacity. We attribute these features to two distinct local packing structures in the vapor-deposited glass, and this interpretation is supported by the strong correlation between the two calorimetric signatures of the glass to liquid transformation. At lower deposition rates, a larger fraction of the sample is prepared in the more stable local packing. The transformation of the vapor-deposited glasses into the supercooled liquid above Tg is exceedingly slow, as much as 4500 times slower than the structural relaxation time of the liquid.

Sedimentology of rocky shorelines: 1. A review of the problem, with analytical methods, and insights gained from the Hulopoe Gravel and the modern rocky shoreline of Lanai, Hawaii

NASA Astrophysics Data System (ADS)

Felton, E. Anne

2002-10-01

Hypotheses advanced concerning the origin of the Pleistocene Hulopoe Gravel on Lanai include mega-tsunami, abandoned beach, 'multiple event,' rocky shoreline, and for parts of the deposit, Native Hawaiian constructions and degraded lava flow fronts. Uplift of Lanai shorelines has been suggested for deposits occurring up to at least 190 m. These conflicting hypotheses highlight problems with the interpretation of coarse gravel deposits containing marine biotic remains. The geological records of the processes implied by these hypotheses should look very different. Discrimination among these or any other hypotheses for the origins of the Hulopoe Gravel will require careful study of vertical and lateral variations in litho- and biofacies, facies architecture, contact relationships and stratal geometries of this deposit. Observations of modern rocky shorelines, particularly on Lanai adjacent to Hulopoe Gravel outcrops, have shown that distinctive coarse gravel facies are present, several of which occur in specific geomorphic settings. Tectonic, isostatic and eustatic changes which cause rapid shoreline translations on steep slopes favour preservation of former rocky shorelines and associated sedimentary deposits both above and below sea level. The sedimentary record of those shorelines is likely to be complex. The modern rocky shoreline sedimentary environment is a hostile one, largely neglected by sedimentologists. A range of high-energy processes characterize these shorelines. Long-period swell, tsunami and storm waves can erode hard bedrock and generate coarse gravel. They also erode older deposits, depositing fresh ones containing mixtures of materials of different ages. Additional gravelly material may be contributed by rivers draining steep hinterlands. To fully evaluate rocky shoreline deposition in the broadest sense, for both the Hulopoe Gravel and other deposits, sedimentary facies models are needed for rocky shorelines occurring in a range of settings. Recognition and description of rocky shoreline deposits are crucial for correctly interpreting the geological history of oceanic and volcanic arc islands, for distinguishing between ancient tsunami and storm deposits, and for interpreting coarse-grained deposits preserved on high energy coasts of continents. Problems include not only the absence of appropriate sedimentary facies models linking rocky shoreline deposits and environments but also, until recently, lack of a systematic descriptive scheme applicable to coarse gravel deposits generally. Two complementary methods serve to integrate the wide range of bed and clast attributes and parameters which characterize complex coarse gravel deposits. The composition and fabric (CAF) method has a materials focus, providing detailed description of attributes of the constituent clasts, petrology, the proportions of gravel, sand and mud, and the ways in which these materials are organized. The sedimentary facies model building (FMB) method emphasizes the organization of a deposit on a bed-by-bed basis to identify facies and infer depositional processes. The systematic use of a comprehensive gravel fabric and petrography log (GFPL), in conjunction with detailed vertical profiles, provides visual representations of a range of deposit characteristics. Criteria useful for distinguishing sedimentary facies in the Hulopoe Gravel are: grain-size modes, amount of matrix, bed geometry, sedimentary structures, bed fabric and clast roundness.

Depositional analysis of Hill sand of Rodessa Formation (lower Cretaceous) in north Shongaloo-Red Rock field, Webster Parish, Louisiana

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adamick, J.A.; Sartin, A.A.

1988-09-01

Hill sand is an informal subdivision of the Lower Cretaceous Rodessa Formation and is a common hydrocarbon reservoir in northeastern Texas, northern Louisiana, and southern Arkansas. The Hill sand is lithologically variable within the study area and consists of conglomerate, fine-grained sandstone, siltstone, mottled red-green claystone, black shale, and limestone. Five depositional environments were interpreted for lithofacies present in Hill sand cores from the North Shongaloo-Red Rock field. These include facies A, fluvial point bar; facies B, crevasse system; facies C, interdistributary bay; facies D, swamp; and facies E, carbonate interdistributary bay. Fluvial point bar and crevasse deposits commonly formmore » hydrocarbon reservoirs in the field. On a regional scale, depositional environments observed in the Hill sand include several fluvial deposystems trending northeast-southwest through Webster Parish. These deposystems terminate into deltaic distributary mouth bars along a northwest-southeast-trending coastline. Areas west of the coastline were occupied by shallow marine environments. Interchannel areas east of the coastline were occupied by interdistributary bay, lake, and crevasse environments in lower deltaic areas, and by lake, swamp, and crevasse environments in upper deltaic areas. Lowermost deposits of the Hill sand throughout the region are interpreted to consist of shallow marine environments. These marine deposits were overlain by thick, predominantly nonmarine sediments. Near the end of Hill sand deposition, the entire region was covered by very shallow marine environments, prior to deposition of the overlying First Lower Anhydrite Stringer.« less

A suture delta: the co-evolution of tectonics and sedimentology as a remnant ocean basin closes; the Indo Burman ranges, northeast India and Bangladesh

NASA Astrophysics Data System (ADS)

Sincavage, R.; Betka, P. M.; Seeber, L.; Steckler, M. S.; Zoramthara, C.

2017-12-01

The closure of an ocean basin involves the interplay of tectonics and sedimentology, whereby thick successions of fluvio-deltaic and shallow marine sediment accumulate in the closing gap between the subduction zone and passive margin. The transition from subduction to collision involves processes that are inherently time-transgressive and co-evolve to influence the nature of the developing tectonic wedge. The Indo-Burman Ranges (IBR) of eastern India present a unique opportunity to examine this scenario on a variety of spatial (10-2­­­-105 m2) and temporal (1 a-10 Ma) scales. Recent field mapping campaigns in the IBR have illuminated analogous depositional environments expressed in the Neogene outcrops of the IBR and the Holocene sediment archive of the Ganges-Brahmaputra-Meghna delta (GBMD). Six distinct lithofacies are present in shallow-marine to fluvial strata of the IBR, containing sedimentary structures that reflect depositional environments correlative with the modern delta. Cyclical alternations of fine sands and silts in packages on the order of 15-20 cm thick define part of the shallow-marine section (M2 facies) that we interpret to represent the foreset beds of the ancient subaqueous delta. The overall scale and sedimentary structures of M2 compare favorably with modern foreset deposits in the Bay of Bengal. Tan-orange medium-grained, well sorted fluvial sandstone that contain large scale (1-10 m) tabular and trough cross bedding represent large-river channel deposits (F2 facies) that overlie the shallow marine strata. F2 deposits bear a striking resemblance in scale and character to bar deposits along the modern Jamuna River. Preliminary grain size analyses on the F2 facies yield grain size distributions that are remarkably consistent with Brahmaputra-sourced mid-Holocene sediments from Sylhet basin within the GBMD. Current research on the GBMD has revealed quantifiable trends in bed thicknesses, downstream fining, and grain size within fluvial deposits. These data will be coupled with ongoing structural and geo- and thermochronology field studies of the IBR that aim to continue to reveal the structural and stratigraphic evolution of this geologically active and densely populated region.

Diverse Deposits in Melas Chasma

NASA Image and Video Library

2015-07-29

This scene captured by NASA Mars Reconnaissance Orbiter includes chaotic deposits with a wide range of colors. The deposits are distinctive with both unique colors and small-scale textures such as fracture patterns. These are probably sedimentary rocks, transported and deposited in water or air. The original layers may have been jumbled in a landslide. Dark or reddish sand dunes cover some of the bedrock. http://photojournal.jpl.nasa.gov/catalog/PIA19860

Hydrologic framework of Long Island, New York

USGS Publications Warehouse

Smolensky, Douglas A.; Buxton, Herbert T.; Shernoff, Peter K.

1990-01-01

Long Island, N.Y., is underlain by a mass of unconsolidated geologic deposits of clay, silt, sand, and gravel that overlie southward-sloping consolidated bedrock. These deposits are thinnest in northern Queens County (northwestern Long Island), where bedrock crops out, and increase to a maximum thickness of 2,000 ft in southeastern Long Island. This sequence of unconsolidated deposits consists of several distinct geologic units ranging in age from late Cretaceous through Pleistocene, with some recent deposits near shores and streams. These units are differentiated by age, depositional environment, and lithology in table 1. Investigations of ground-water availability and flow patterns may require information on the internal geometry of the hydrologic system that geologic correlations and interpretation alone cannot provide; hydrologic interpretations in which deposits are differentiated on the basis of water-transmitting properties are generally needed also. This set of maps and vertical sections depicts the hydrogeologic framework of the unconsolidated deposits that form Long Island's ground-water system. These deposits can be classified into eight major hydrogeologic units (table 1). The hydrogeologic interpretations presented herein are not everywhere consistent with strict geologic interpretation owing to facies changes and local variations in the water-transmitting properties within geologic units. These maps depict the upper-surface altitude of seven of the eight hydrogeologic units, which, in ascending order, are: consolidated bedrock, Lloyd aquifer, Raritan confining unit, Magothy aquifer, Monmouth greensand, Jameco aquifer, and Gardiners Clay. The upper glacial aquifer—the uppermost unit—is at land surface over most of Long Island and is, therefore, not included. The nine north-south hydrogeologic sections shown below depict the entire sequence of unconsolidated deposits and, together with the maps, provide a detailed three-dimensional interpretation of Long Island's hydrogeologic framework. The structure-contour map that shows the upper-surface altitude of the Cretaceous deposits is included to illustrate the erosional unconformity between the Cretaceous and overlying Pleistocene deposits. Pleistocene erosion played a major role in determining the shape and extent of the Lloyd aquifer, the Raritan confining unit, and the Magothy aquifer, and thus partly determined their hydrogeologic relation with subsequent (post-Cretaceous) deposits.

Rare earth element geochemistry of shallow carbonate outcropping strata in Saudi Arabia: Application for depositional environments prediction

NASA Astrophysics Data System (ADS)

Eltom, Hassan A.; Abdullatif, Osman M.; Makkawi, Mohammed H.; Eltoum, Isam-Eldin A.

2017-03-01

The interpretation of depositional environments provides important information to understand facies distribution and geometry. The classical approach to interpret depositional environments principally relies on the analysis of lithofacies, biofacies and stratigraphic data, among others. An alternative method, based on geochemical data (chemical element data), is advantageous because it can simply, reproducibly and efficiently interpret and refine the interpretation of the depositional environment of carbonate strata. Here we geochemically analyze and statistically model carbonate samples (n = 156) from seven sections of the Arab-D reservoir outcrop analog of central Saudi Arabia, to determine whether the elemental signatures (major, trace and rare earth elements [REEs]) can be effectively used to predict depositional environments. We find that lithofacies associations of the studied outcrop (peritidal to open marine depositional environments) possess altered REE signatures, and that this trend increases stratigraphically from bottom-to-top, which corresponds to an upward shallowing of depositional environments. The relationship between REEs and major, minor and trace elements indicates that contamination by detrital materials is the principal source of REEs, whereas redox condition, marine and diagenetic processes have minimal impact on the relative distribution of REEs in the lithofacies. In a statistical model (factor analysis and logistic regression), REEs, major and trace elements cluster together and serve as markers to differentiate between peritidal and open marine facies and to differentiate between intertidal and subtidal lithofacies within the peritidal facies. The results indicate that statistical modelling of the elemental composition of carbonate strata can be used as a quantitative method to predict depositional environments and regional paleogeography. The significance of this study lies in offering new assessments of the relationships between lithofacies and geochemical elements by using advanced statistical analysis, a method that could be used elsewhere to interpret depositional environment and refine facies models.

Surface morphology of a modified ballistic deposition model.

PubMed

Banerjee, Kasturi; Shamanna, J; Ray, Subhankar

2014-08-01

The surface and bulk properties of a modified ballistic deposition model are investigated. The deposition rule interpolates between nearest- and next-nearest-neighbor ballistic deposition and the random deposition models. The stickiness of the depositing particle is controlled by a parameter and the type of interparticle force. Two such forces are considered: Coulomb and van der Waals type. The interface width shows three distinct growth regions before eventual saturation. The rate of growth depends more strongly on the stickiness parameter than on the type of interparticle force. However, the porosity of the deposits is strongly influenced by the interparticle force.

Preserved Filamentous Microbial Biosignatures in the Brick Flat Gossan, Iron Mountain, California

PubMed Central

Sumner, Dawn Y.; Alpers, Charles N.; Karunatillake, Suniti; Hofmann, Beda A.

2015-01-01

Abstract A variety of actively precipitating mineral environments preserve morphological evidence of microbial biosignatures. One such environment with preserved microbial biosignatures is the oxidized portion of a massive sulfide deposit, or gossan, such as that at Iron Mountain, California. This gossan may serve as a mineralogical analogue to some ancient martian environments due to the presence of oxidized iron and sulfate species, and minerals that only form in acidic aqueous conditions, in both environments. Evaluating the potential biogenicity of cryptic textures in such martian gossans requires an understanding of how microbial textures form biosignatures on Earth. The iron-oxide-dominated composition and morphology of terrestrial, nonbranching filamentous microbial biosignatures may be distinctive of the underlying formation and preservation processes. The Iron Mountain gossan consists primarily of ferric oxide (hematite), hydrous ferric oxide (HFO, predominantly goethite), and jarosite group minerals, categorized into in situ gossan, and remobilized iron deposits. We interpret HFO filaments, found in both gossan types, as HFO-mineralized microbial filaments based in part on (1) the presence of preserved central filament lumina in smooth HFO mineral filaments that are likely molds of microbial filaments, (2) mineral filament formation in actively precipitating iron-oxide environments, (3) high degrees of mineral filament bending consistent with a flexible microbial filament template, and (4) the presence of bare microbial filaments on gossan rocks. Individual HFO filaments are below the resolution of the Mars Curiosity and Mars 2020 rover cameras, but sinuous filaments forming macroscopic matlike textures are resolvable. If present on Mars, available cameras may resolve these features identified as similar to terrestrial HFO filaments and allow subsequent evaluation for their biogenicity by synthesizing geochemical, mineralogical, and morphological analyses. Sinuous biogenic filaments could be preserved on Mars in an iron-rich environment analogous to Iron Mountain, with the Pahrump Hills region and Hematite Ridge in Gale Crater as tentative possibilities. Key Words: Geobiology—Biosignatures—Filaments—Mars—Microbial fossils. Astrobiology 15, 637–668. PMID:26247371

Preserved Filamentous Microbial Biosignatures in the Brick Flat Gossan, Iron Mountain, California.

PubMed

Williams, Amy J; Sumner, Dawn Y; Alpers, Charles N; Karunatillake, Suniti; Hofmann, Beda A

2015-08-01

A variety of actively precipitating mineral environments preserve morphological evidence of microbial biosignatures. One such environment with preserved microbial biosignatures is the oxidized portion of a massive sulfide deposit, or gossan, such as that at Iron Mountain, California. This gossan may serve as a mineralogical analogue to some ancient martian environments due to the presence of oxidized iron and sulfate species, and minerals that only form in acidic aqueous conditions, in both environments. Evaluating the potential biogenicity of cryptic textures in such martian gossans requires an understanding of how microbial textures form biosignatures on Earth. The iron-oxide-dominated composition and morphology of terrestrial, nonbranching filamentous microbial biosignatures may be distinctive of the underlying formation and preservation processes. The Iron Mountain gossan consists primarily of ferric oxide (hematite), hydrous ferric oxide (HFO, predominantly goethite), and jarosite group minerals, categorized into in situ gossan, and remobilized iron deposits. We interpret HFO filaments, found in both gossan types, as HFO-mineralized microbial filaments based in part on (1) the presence of preserved central filament lumina in smooth HFO mineral filaments that are likely molds of microbial filaments, (2) mineral filament formation in actively precipitating iron-oxide environments, (3) high degrees of mineral filament bending consistent with a flexible microbial filament template, and (4) the presence of bare microbial filaments on gossan rocks. Individual HFO filaments are below the resolution of the Mars Curiosity and Mars 2020 rover cameras, but sinuous filaments forming macroscopic matlike textures are resolvable. If present on Mars, available cameras may resolve these features identified as similar to terrestrial HFO filaments and allow subsequent evaluation for their biogenicity by synthesizing geochemical, mineralogical, and morphological analyses. Sinuous biogenic filaments could be preserved on Mars in an iron-rich environment analogous to Iron Mountain, with the Pahrump Hills region and Hematite Ridge in Gale Crater as tentative possibilities.

Preserved filamentous microbial biosignatures in the Brick Flat gossan, Iron Mountain, California

USGS Publications Warehouse

Williams, Amy J.; Sumner, Dawn Y.; Alpers, Charles N.; Karunatillake, Suniti; Hofmann, Beda A

2015-01-01

A variety of actively precipitating mineral environments preserve morphological evidence of microbial biosignatures. One such environment with preserved microbial biosignatures is the oxidized portion of a massive sulfide deposit, or gossan, such as that at Iron Mountain, California. This gossan may serve as a mineralogical analogue to some ancient martian environments due to the presence of oxidized iron and sulfate species, and minerals that only form in acidic aqueous conditions, in both environments. Evaluating the potential biogenicity of cryptic textures in such martian gossans requires an understanding of how microbial textures form biosignatures on Earth. The iron-oxide-dominated composition and morphology of terrestrial, nonbranching filamentous microbial biosignatures may be distinctive of the underlying formation and preservation processes. The Iron Mountain gossan consists primarily of ferric oxide (hematite), hydrous ferric oxide (HFO, predominantly goethite), and jarosite group minerals, categorized into in situ gossan, and remobilized iron deposits. We interpret HFO filaments, found in both gossan types, as HFO-mineralized microbial filaments based in part on (1) the presence of preserved central filament lumina in smooth HFO mineral filaments that are likely molds of microbial filaments, (2) mineral filament formation in actively precipitating iron-oxide environments, (3) high degrees of mineral filament bending consistent with a flexible microbial filament template, and (4) the presence of bare microbial filaments on gossan rocks. Individual HFO filaments are below the resolution of the Mars Curiosity and Mars 2020 rover cameras, but sinuous filaments forming macroscopic matlike textures are resolvable. If present on Mars, available cameras may resolve these features identified as similar to terrestrial HFO filaments and allow subsequent evaluation for their biogenicity by synthesizing geochemical, mineralogical, and morphological analyses. Sinuous biogenic filaments could be preserved on Mars in an iron-rich environment analogous to Iron Mountain, with the Pahrump Hills region and Hematite Ridge in Gale Crater astentative possibilities.

Stratigraphy of the Younger Dryas Chronozone and paleoenvironmental implications: Central and Southern Great Plains

USGS Publications Warehouse

Holliday, V.T.; Meltzer, D.J.; Mandel, R.

2011-01-01

The Great Plains of the United States was the setting for some of the earliest research in North America into patterns and changes in the character of late Pleistocene environments and their effects on contemporary human populations. Many localities in the region have well-stratified records of terminal Pleistocene and early Holocene human (Paleoindian) activity and past environments. These have proven important in debates over the character of the Younger Dryas Chronozone (YDC; 11,000-10,000 14C BP; 12,900-11,700 cal BP) in the continental interior. This paper reviews the lithostratigraphic record of the YDC on the Central and Southern Great Plains and summarizes paleobiological records (largely isotopic). The goal is to determine if there is any uniformity in the timing, character, direction and/or magnitude of changes in depositional environments or broader geomorphic systems before, during or after the YDC in order to address the question of the character of environments through this time. The stratigraphic records of the late Pleistocene to early Holocene transition, and in particular, the stratigraphic records of the YDC vary through time and space. The data clearly show that a host of geomorphic processes produced the terminal Pleistocene and early Holocene stratigraphic records of the Great Plains. Moreover, the YDC is not necessarily manifest as a distinct lithostratigraphic or biostratigraphic entity in these different types of deposits and soils. The various geomorphic systems of the Great Plains did not behave synchronously in response to any common climate driver. These stratigraphic records reflect local environmental conditions and probably a complex response to the reorganization of mid-latitude climates in the terminal Pleistocene and early Holocene. ?? 2011 Elsevier Ltd and INQUA.

Excavation and aggregation as organizing factors in de novo construction by mound-building termites.

PubMed

Green, Ben; Bardunias, Paul; Turner, J Scott; Nagpal, Radhika; Werfel, Justin

2017-06-14

Termites construct complex mounds that are orders of magnitude larger than any individual and fulfil a variety of functional roles. Yet the processes through which these mounds are built, and by which the insects organize their efforts, remain poorly understood. The traditional understanding focuses on stigmergy, a form of indirect communication in which actions that change the environment provide cues that influence future work. Termite construction has long been thought to be organized via a putative 'cement pheromone': a chemical added to deposited soil that stimulates further deposition in the same area, thus creating a positive feedback loop whereby coherent structures are built up. To investigate the detailed mechanisms and behaviours through which termites self-organize the early stages of mound construction, we tracked the motion and behaviour of major workers from two Macrotermes species in experimental arenas. Rather than a construction process focused on accumulation of depositions, as models based on cement pheromone would suggest, our results indicated that the primary organizing mechanisms were based on excavation. Digging activity was focused on a small number of excavation sites, which in turn provided templates for soil deposition. This behaviour was mediated by a mechanism of aggregation, with termites being more likely to join in the work at an excavation site as the number of termites presently working at that site increased. Statistical analyses showed that this aggregation mechanism was a response to active digging, distinct from and unrelated to putative chemical cues that stimulate deposition. Agent-based simulations quantitatively supported the interpretation that the early stage of de novo construction is primarily organized by excavation and aggregation activity rather than by stigmergic deposition. © 2017 The Author(s).

Excavation and aggregation as organizing factors in de novo construction by mound-building termites

PubMed Central

Bardunias, Paul; Turner, J. Scott; Nagpal, Radhika; Werfel, Justin

2017-01-01

Termites construct complex mounds that are orders of magnitude larger than any individual and fulfil a variety of functional roles. Yet the processes through which these mounds are built, and by which the insects organize their efforts, remain poorly understood. The traditional understanding focuses on stigmergy, a form of indirect communication in which actions that change the environment provide cues that influence future work. Termite construction has long been thought to be organized via a putative ‘cement pheromone’: a chemical added to deposited soil that stimulates further deposition in the same area, thus creating a positive feedback loop whereby coherent structures are built up. To investigate the detailed mechanisms and behaviours through which termites self-organize the early stages of mound construction, we tracked the motion and behaviour of major workers from two Macrotermes species in experimental arenas. Rather than a construction process focused on accumulation of depositions, as models based on cement pheromone would suggest, our results indicated that the primary organizing mechanisms were based on excavation. Digging activity was focused on a small number of excavation sites, which in turn provided templates for soil deposition. This behaviour was mediated by a mechanism of aggregation, with termites being more likely to join in the work at an excavation site as the number of termites presently working at that site increased. Statistical analyses showed that this aggregation mechanism was a response to active digging, distinct from and unrelated to putative chemical cues that stimulate deposition. Agent-based simulations quantitatively supported the interpretation that the early stage of de novo construction is primarily organized by excavation and aggregation activity rather than by stigmergic deposition. PMID:28615497

Dust deposition on the decks of the Mars Exploration Rovers: 10 years of dust dynamics on the Panoramic Camera calibration targets.

PubMed

Kinch, Kjartan M; Bell, James F; Goetz, Walter; Johnson, Jeffrey R; Joseph, Jonathan; Madsen, Morten Bo; Sohl-Dickstein, Jascha

2015-05-01

The Panoramic Cameras on NASA's Mars Exploration Rovers have each returned more than 17,000 images of their calibration targets. In order to make optimal use of this data set for reflectance calibration, a correction must be made for the presence of air fall dust. Here we present an improved dust correction procedure based on a two-layer scattering model, and we present a dust reflectance spectrum derived from long-term trends in the data set. The dust on the calibration targets appears brighter than dusty areas of the Martian surface. We derive detailed histories of dust deposition and removal revealing two distinct environments: At the Spirit landing site, half the year is dominated by dust deposition, the other half by dust removal, usually in brief, sharp events. At the Opportunity landing site the Martian year has a semiannual dust cycle with dust removal happening gradually throughout two removal seasons each year. The highest observed optical depth of settled dust on the calibration target is 1.5 on Spirit and 1.1 on Opportunity (at 601 nm). We derive a general prediction for dust deposition rates of 0.004 ± 0.001 in units of surface optical depth deposited per sol (Martian solar day) per unit atmospheric optical depth. We expect this procedure to lead to improved reflectance-calibration of the Panoramic Camera data set. In addition, it is easily adapted to similar data sets from other missions in order to deliver improved reflectance calibration as well as data on dust reflectance properties and deposition and removal history.

Stratigraphy and paleohydrology of delta channel deposits, Jezero crater, Mars

NASA Astrophysics Data System (ADS)

Goudge, Timothy A.; Mohrig, David; Cardenas, Benjamin T.; Hughes, Cory M.; Fassett, Caleb I.

2018-02-01

The Jezero crater open-basin lake contains two well-exposed fluvial sedimentary deposits formed early in martian history. Here, we examine the geometry and architecture of the Jezero western delta fluvial stratigraphy using high-resolution orbital images and digital elevation models (DEMs). The goal of this analysis is to reconstruct the evolution of the delta and associated shoreline position. The delta outcrop contains three distinct classes of fluvial stratigraphy that we interpret, from oldest to youngest, as: (1) point bar strata deposited by repeated flood events in meandering channels; (2) inverted channel-filling deposits formed by avulsive distributary channels; and (3) a valley that incises the deposit. We use DEMs to quantify the geometry of the channel deposits and estimate flow depths of ∼7 m for the meandering channels and ∼2 m for the avulsive distributary channels. Using these estimates, we employ a novel approach for assessing paleohydrology of the formative channels in relative terms. This analysis indicates that the shift from meandering to avulsive distributary channels was associated with an approximately four-fold decrease in the water to sediment discharge ratio. We use observations of the fluvial stratigraphy and channel paleohydrology to propose a model for the evolution of the Jezero western delta. The delta stratigraphy records lake level rise and shoreline transgression associated with approximately continuous filling of the basin, followed by outlet breaching, and eventual erosion of the delta. Our results imply a martian surface environment during the period of delta formation that supplied sufficient surface runoff to fill the Jezero basin without major drops in lake level, but also with discrete flooding events at non-orbital (e.g., annual to decadal) timescales.

Dust deposition on the decks of the Mars Exploration Rovers: 10 years of dust dynamics on the Panoramic Camera calibration targets

PubMed Central

Bell, James F.; Goetz, Walter; Johnson, Jeffrey R.; Joseph, Jonathan; Madsen, Morten Bo; Sohl‐Dickstein, Jascha

2015-01-01

Abstract The Panoramic Cameras on NASA's Mars Exploration Rovers have each returned more than 17,000 images of their calibration targets. In order to make optimal use of this data set for reflectance calibration, a correction must be made for the presence of air fall dust. Here we present an improved dust correction procedure based on a two‐layer scattering model, and we present a dust reflectance spectrum derived from long‐term trends in the data set. The dust on the calibration targets appears brighter than dusty areas of the Martian surface. We derive detailed histories of dust deposition and removal revealing two distinct environments: At the Spirit landing site, half the year is dominated by dust deposition, the other half by dust removal, usually in brief, sharp events. At the Opportunity landing site the Martian year has a semiannual dust cycle with dust removal happening gradually throughout two removal seasons each year. The highest observed optical depth of settled dust on the calibration target is 1.5 on Spirit and 1.1 on Opportunity (at 601 nm). We derive a general prediction for dust deposition rates of 0.004 ± 0.001 in units of surface optical depth deposited per sol (Martian solar day) per unit atmospheric optical depth. We expect this procedure to lead to improved reflectance‐calibration of the Panoramic Camera data set. In addition, it is easily adapted to similar data sets from other missions in order to deliver improved reflectance calibration as well as data on dust reflectance properties and deposition and removal history. PMID:27981072

The microbial nature of laminated limestones: Lessons from the Upper Aptian, Araripe Basin, Brazil

NASA Astrophysics Data System (ADS)

Catto, Bruno; Jahnert, Ricardo Jorge; Warren, Lucas Verissimo; Varejao, Filipe Giovanini; Assine, Mario Luis

2016-07-01

The Araripe Basin, located in northeastern Brazil, originated during the Gondwana continental break-up responsible for the opening of the South Atlantic during the Early Cretaceous. In the Araripe Basin, the post-rift Aptian sequence corresponds to the Santana Group, which is composed, in upward succession, of mostly clastic continental and rare carbonate layers of the Barbalha, Crato, Ipubi and Romualdo Formations. The laminated limestones of the Crato Formation were deposited in a lacustrine environment preceding the deposition of the Ipubi Formation evaporites. They are age-equivalent to the limestones of the pre-salt interval of the east coast of Brazil, which contains large petroleum reserves. The excellent preservation of its macrofossils has made the Crato Formation known worldwide as a Fossil Lagerstätte. The limestones are macroscopically homogeneous, and their deposition has been previously attributed to chemical precipitation. Although the carbonate laminites are macroscopically undifferentiated, mineralogical variations, microscopic texture and distinctive biotic aspects supported the characterization of four microfacies: planar laminated, crustiform, nodular and rhythmic. The microfacies analysis indicated a strong and pervasive biological activity in the Crato limestone morphogenesis. Organominerals precipitated by the metabolic action of cyanobacteria and/or sulfate-reducing bacteria and methanogenic-oxidizing archea are represented by calcite and pyrite. Calcified coccoid and filaments are common, furthermore, the presence of calcified biofilms composed of exopolymeric substances (EPS) is ubiquitous. The presence of amorphous organic matter (AOM) and gypsum, particularly in the rhythmic microfacies, indicates anoxic/dysoxic conditions and stressful environments during periods of drought and low lake levels which favored the development and preservation of microbial biofilms. Phytoclasts and miospores when present in the succession indicate an extrabasinal contribution during wetter periods, although the environment remained of very low energy. The evidence of microbial influence in the formation of the laminated limestones of the Crato Formation is of great importance for understanding the excellent preservation of the unit's fossils and for modeling the evolution of the Aptian carbonate sequences in Brazil.

Tectonic evolution of part of the Southern Metamorphic Belt of the Armorican Massif including the Ile de Groix

NASA Astrophysics Data System (ADS)

Richards, Lawrence Edward

The Southern Metamorphic Belt (SMB) of the Armorican Massifextends 400km along the south coast of Brittany and into Vendee. It is separated from the Central Armorican Domain by a major, late-Hercynian shear belt, known as the South Armorican Shear Zone. In the area studied, belts of metasedimentary and metavolcanic schist of uncertain age are separated by belts of granitic gneiss; areas of migmatite and Hercynian granite plutons cross-cut these belts. Three distinctive lithologic assemblages have been identified in the schist belts, characteristic of different depositional environments: the Le Pouldu Group, Kerleven and Gouesnach formations probably originated as abyssal black shales deposited on oceanic crust; the St. Laurent Formation and Melgven Schists probably formed as distal greywacke deposits on a deep continental shelf; the Nerly and Beg-Meil formations probably formed in a proximal marine or fluviatile environment. These disparate assemblages were tectonically juxtaposed by overthrusting (obduction) before an amphibolite facies metamorphism and deformation during the Cadomian Orogeny. The Moelan Gneiss, a Lower Ordovician alkali-granite intrusion, postdates M1/D1 and probably formed in a rifting environment at the onset of ocean-floor spreading along an axis south of the present Armorican Massif. The famous blueschists of the Ile de Groix probably formed in a subduction zone on the south side of the ocean and were obducted onto the passive southern margin of the Armorican Massif following closure of the ocean and continental collision. A second phase of regional deformation, producing a cataclastic foliation in the Moelan Gneiss, probably resulted from the collision. Large-scale overthrusting of the southern continent onto the Armorican Massif took place, causing metamorphism with partial melting at depth generating migmatites. A third phase of pervasive deformation may correlate with oroclinal bending of the Ibero-Armorican Arc during the Hercynian Orogeny.

Diagenetic pathways in deposits of cool- and cold-water carbonate factories

NASA Astrophysics Data System (ADS)

Frank, T. D.; James, N. P.

2017-12-01

This investigation integrates sedimentological, petrographic, and geochemical observations from modern and ancient heterozoan carbonate deposits that formed at temperate to polar latitudes with the aim of evaluating diagenetic pathways characteristic of these systems. These factories operate under conditions distinct from those of photozoan counterparts. Lower temperatures, higher trophic resources, lower carbonate saturation states, and strong seasonality govern not only the nature of carbonate communities, but also how deposits translate into the rock record. In these settings, carbonate production is entirely biogenic, assemblages are of low diversity, and there are no significant calcareous phototrophs. Aragonitic taxa may be present in living communities, but allochems rapidly disappear via dissolution. Carbonate producers are not capable of building rigid frameworks, so their deposits accumulate as sands and gravels and are prone to winnowing and reworking. Low production rates lead to long seafloor residence times (1000s of years) for grains, which undergo physical reworking, dissolution, and repeated infestation by endolithic borers. Microborings remain empty, increasing grain susceptibility to disintegration. Intergranular cementation on the seafloor is rare and restricted to hardgrounds. Periods of subaerial exposure do not leave traces of meteoric alteration. Results show that the deposits of heterozoan carbonate factories tend enter the geologic record as taphonomic remnants, namely reworked, unconsolidated sands and gravels with low diagenetic potential. During burial, physical and chemical compaction produce limestones with tightly packed, grain-supported fabrics, often with grains in sutured contact. Significant cementation is associated with the deep burial realm. Results reveal a dramatically different diagenetic pathway than is typical for deposits of tropical photozoan factories, in which significant recrystallization and lithification occur on the seafloor and upon subaerial exposure. Interpretations of ancient deposits should take into account the potential for taphonomic loss of aragonitic allochems, modification of depositional textures via reworking and compaction, and grain alteration and cementation focused in the burial environment.

Atmospheric chemistry of mercury in Antarctica and the role of cryptogams to assess deposition patterns in coastal ice-free areas.

PubMed

Bargagli, R

2016-11-01

Mercury in the Antarctic troposphere has a distinct chemistry and challenging long-term measurements are needed for a better understanding of the atmospheric Hg reactions with oxidants and the exchanges of the various mercury forms among air-snow-sea and biota. Antarctic mosses and lichens are reliable biomonitors of airborne metals and in short time they can give useful information about Hg deposition patterns. Data summarized in this review show that although atmospheric Hg concentrations in the Southern Hemisphere are lower than those in the Northern Hemisphere, Antarctic cryptogams accumulate Hg at levels in the same range or higher than those observed for related cryptogam species in the Arctic, suggesting an enhanced deposition of bioavailable Hg in Antarctic coastal ice-free areas. In agreement with the newest findings in the literature, the Hg bioaccumulation in mosses and lichens from a nunatak particularly exposed to strong katabatic winds can be taken as evidence for a Hg contribution to coastal ecosystems by air masses from the Antarctic plateau. Human activities on the continent are mostly concentrated in coastal ice-free areas, and the deposition in these areas of Hg from the marine environment, the plateau and anthropogenic sources raises concern. The use of Antarctic cryptogams as biomonitors will be very useful to map Hg deposition patterns in costal ice-free areas and will contribute to a better understanding of Hg cycling in Antarctica and its environmental fate in terrestrial ecosystems. Copyright © 2016 Elsevier Ltd. All rights reserved.

Ages and Origins of Calcite and Opal in the Exploratory Studies Facility Tunnel, Yucca Mountain, Nevada

USGS Publications Warehouse

Paces, James B.; Neymark, Leonid A.; Marshall, Brian D.; Whelan, Joseph F.; Peterman, Zell E.

2001-01-01

Deposits of calcite and opal are present as coatings on open fractures and lithophysal cavities in unsaturated-zone tuffs at Yucca Mountain, Nevada, site of a potential high-level radioactive waste repository. Outermost layers of calcite and opal have radiocarbon ages of 16,000 to 44,000 years before present and thorium-230/uranium ages of 28,000 to more than 500,000 years before present. These ages are young relative to the 13-million-year age of the host rocks. Multiple subsamples from the same outer layer typically show a range of ages with youngest ages from the thinnest subsamples. Initial uranium-234/uranium-238 activity ratios between 1 and 9.5 show a distinct negative correlation with thorium-230/uranium age and are greater than 4 for all but one sample younger than 100,000 years before present. These data, along with micrometer-scale layering and distinctive crystal morphologies, are interpreted to indicate that deposits formed very slowly from water films migrating through open cavities. Exchanges of carbon dioxide and water vapor probably took place between downward-migrating liquids and upward-migrating gases at low rates, resulting in oversaturation of mineral constituents at crystal extremities and more or less continuous deposition of very thin layers. Therefore, subsamples represent mixtures of older and younger layers on a scale finer than sampling techniques can resolve. Slow, long-term rates of deposition (less than about 5 millimeters of mineral per million years) are inferred from subsamples of outermost calcite and opal. These growth rates are similar to those calculated assuming that total coating thicknesses of 10 to 40 millimeters accumulated over 12 million years. Calcite has a wide range of delta carbon-13 values from about -8.2 to 8.5 per mil and delta oxygen-18 values from about 10 to 21 per mil. Systematic microsampling across individual mineral coatings indicates basal (older) calcite tends to have the largest delta carbon-13 values and smallest delta oxygen-18 values compared to calcite from intermediate and outer positions. Basal calcite has relatively small strontium-87/strontium-86 ratios, between 0.7105 and 0.7120, that are similar to the initial isotopic compositions of the strontium-rich tuff units, whereas outer calcite has more radiogenic strontium-87/strontium-86 ratios between 0.7115 and 0.7127. Isotopic compositions of strontium, oxygen, and carbon in the outer (youngest) unsaturated-zone calcite are coincident with those measured in Yucca Mountain calcrete, which formed by pedogenic processes. The physical and isotopic data from calcite and opal indicate that they formed from solutions of meteoric origin percolating through a limited network of connected fracture pathways in the unsaturated zone rather than by inundation from ascending ground water originating in the saturated zone. Mineral assemblages, textures, and distributions within the unsaturated zone are distinctly different from those deposited below the water table at Yucca Mountain. The calcite and opal typically are present only on footwall surfaces of a small fraction of fractures and only on floors of a small fraction of lithophysal cavities. The similarities in the carbon, oxygen, and strontium isotopic compositions between fracture calcite and soil-zone calcite, as well as the gradation of textures from detritus-rich micrite in the soil to detritus-free spar 10 to 30 meters below the surface, also support a genetic link between the two depositional environments. Older deposits contain oxygen isotope compositions that indicate elevated temperatures of mineral formation during the early stages of deposition; however, in the youngest deposits these values are consistent with deposition under geothermal gradients similar to modern conditions. Correlations between mineral ages and varying Pleistocene climate conditions are not apparent from the current data. Cumulative evidence from calcite and opal deposits indicate

Preservation of Late Amazonian Mars ice and water-related deposits in a unique crater environment in Noachis Terra: Age relationships between lobate debris tongues and gullies

NASA Astrophysics Data System (ADS)

Morgan, Gareth A.; Head, James W.; Marchant, David R.

2011-01-01

The Amazonian period of Mars has been described as static, cold, and dry. Recent analysis of high-resolution imagery of equatorial and mid-latitude regions has revealed an array of young landforms produced in association with ice and liquid water; because near-surface ice in these regions is currently unstable, these ice-and-water-related landforms suggest one or more episodes of martian climate change during the Amazonian. Here we report on the origin and evolution of valley systems within a degraded crater in Noachis Terra, Asimov Crater. The valleys have produced a unique environment in which to study the geomorphic signals of Amazonian climate change. New high-resolution images reveal Hesperian-aged layered basalt with distinctive columnar jointing capping interior crater fill and providing debris, via mass wasting, for the surrounding annular valleys. The occurrence of steep slopes (>20°), relatively narrow (sheltered) valleys, and a source of debris have provided favorable conditions for the preservation of shallow-ice deposits. Detailed mapping reveals morphological evidence for viscous ice flow, in the form of several lobate debris tongues (LDT). Superimposed on LDT are a series of fresh-appearing gullies, with typical alcove, channel, and fan morphologies. The shift from ice-rich viscous-flow formation to gully erosion is best explained as a shift in martian climate, from one compatible with excess snowfall and flow of ice-rich deposits, to one consistent with minor snow and gully formation. Available dating suggests that the climate transition occurred >8 Ma, prior to the formation of other small-scale ice-rich flow features identified elsewhere on Mars that have been interpreted to have formed during the most recent phases of high obliquity. Taken together, these older deposits suggest that multiple climatic shifts have occurred over the last tens of millions of years of martian history.

Recently Deglaciated High-Altitude Soils of the Himalaya: Diverse Environments, Heterogenous Bacterial Communities and Long-Range Dust Inputs from the Upper Troposphere

PubMed Central

Stres, Blaz; Sul, Woo Jun; Murovec, Bostjan; Tiedje, James M.

2013-01-01

Background The Himalaya with its altitude and geographical position forms a barrier to atmospheric transport, which produces much aqueous-particle monsoon precipitation and makes it the largest continuous ice-covered area outside polar regions. There is a paucity of data on high-altitude microbial communities, their native environments and responses to environmental-spatial variables relative to seasonal and deglaciation events. Methodology/Principal Findings Soils were sampled along altitude transects from 5000 m to 6000 m to determine environmental, spatial and seasonal factors structuring bacterial communities characterized by 16 S rRNA gene deep sequencing. Dust traps and fresh-snow samples were used to assess dust abundance and viability, community structure and abundance of dust associated microbial communities. Significantly different habitats among the altitude-transect samples corresponded to both phylogenetically distant and closely-related communities at distances as short as 50 m showing high community spatial divergence. High within-group variability that was related to an order of magnitude higher dust deposition obscured seasonal and temporal rearrangements in microbial communities. Although dust particle and associated cell deposition rates were highly correlated, seasonal dust communities of bacteria were distinct and differed significantly from recipient soil communities. Analysis of closest relatives to dust OTUs, HYSPLIT back-calculation of airmass trajectories and small dust particle size (4–12 µm) suggested that the deposited dust and microbes came from distant continental, lacustrine and marine sources, e.g. Sahara, India, Caspian Sea and Tibetan plateau. Cyanobacteria represented less than 0.5% of microbial communities suggesting that the microbial communities benefitted from (co)deposited carbon which was reflected in the psychrotolerant nature of dust-particle associated bacteria. Conclusions/Significance The spatial, environmental and temporal complexity of the high-altitude soils of the Himalaya generates ongoing disturbance and colonization events that subject heterogeneous microniches to stochastic colonization by far away dust associated microbes and result in the observed spatially divergent bacterial communities. PMID:24086740

Climate controlled peat accumulation at Colônia (São Paulo, SE / Brazil) since the last interglacial

NASA Astrophysics Data System (ADS)

Roeser, Patricia; Ledru, Marie-Pierre; Thouveny, Nicolas; Tachikawa, Kazuyo; Rostek, Frauke; Garcia, Marta; Struck, Ulrich; Sawakuchi, André; Favier, Charly; Bard, Edouard

2017-04-01

The Colônia site is situated 40 km south of the mega city São Paulo, within a geomorphological structure probably formed by a meteor impact. The regional yearly rainfall pattern is under the domain of the South American Summer Monsoon, with increased summer rainfall accompanied by increasing temperatures. During the austral winter, southern frontal systems act as moisture source and relate to colder temperatures. The vegetation history from the peatland sediments had already shown noticeable changes since 125 ka (Ledru et al, 2009). The previous reconstruction is herewith complemented by investigations of the inorganic portions of the sediments. The age model of the present study bases on radiocarbon ages, luminescence ages and paleomagnetism. The detrital input (e.g. K, Ti, Si [XRF counts]) allowed the identification of phases deposited under increased water table depth, containing older carbon with respect to the stratigraphic counterparts deposited under lower water table conditions. The degree of crystallinity, as obtained from X-ray diffraction data, clearly outlines alternations between ombrotrophic peat accumulation and minerotrophic accumulation. These two deposition environments present distinct geochemical signature (from K, Rb, Si, Ti, Zr, Fe, Ca, S [high resolution XRF counts]), as supported by compositional data analysis. Inserted in the context of South American paleoclimate, the change of the peatland deposition environment towards minerotrophic conditions correlates well to time periods in which the overall region received increased moisture. Such conditions relate to changes in precipitation and seasonality regulated by the South American Summer Monsoon variability, as also observed in supra-regional paleoclimate records, e.g. speleothem records, the Cariaco Basin and concomitant increased detrital input to the continental margin at SE-Brazi as shown by marine sediments. These conditions partly overlap with time periods of colder temperatures and enhanced frequency of southern frontal systems, as shown by several phases of Araucaria pollen occurrence in the Colônia peatland.

Quaternary sedimentation and subsidence history of Lake Baikal, Siberia, based on seismic stratigraphy and coring

USGS Publications Warehouse

Colman, Steven M.; Karabanov, E.B.; Nelson, C. H.

2003-01-01

The long, continuous, high-latitude, stratigraphic record of Lake Baikal was deposited in three broad sedimentary environments, defined by high-resolution seismic-reflection and coring methods: (1) turbidite depositional systems, by far the most widespread, characterizing most of the margins and floors of the main basins of the lake, (2) large deltas of major drainages, and (3) tectonically or topographically isolated ridges and banks. Holocene sedimentation rates based on radiocarbon ages vary by more than an order of magnitude among these environments, from less than about 0.03 mm/yr on ridges and banks to more than about 0.3 mm/yr on basin floors. Extrapolating these rates, with a correction for compaction, yields tentative estimates of about 25 and 11 Ma for the inception of rifting in the Central and North basins, respectively, and less than 6 Ma for the 200-m sediment depth on Academician Ridge. The Selenga Delta has the distinctive form of a classic prograding Gilbert-type delta, but its history appears to represent a complex combination of tectonism and sedimentation. The central part of the delta is underlain by prograding, shallow-water sequences, now several hundred meters below the lake surface. These deposits and much of the delta slope are mantled by fine-grained, deep-water, hemipelagic deposits whose base is estimated to be about 650,000 years old. Modern coarse-grained sediment bypasses the delta slope through fault-controlled canyons that feed large, subaqueous fans at the ends of the South and Central basins. These relations, along with abundant other evidence of recent faulting and the great depths of the Central and South basins, suggest that these two rift basins have experienced a period of unusually rapid subsidence over the last 650,000 years, during at least part of which sedimentation has failed to keep pace.

Oncoidal granular iron formation in the Mesoarchaean Pongola Supergroup, southern Africa: Textural and geochemical evidence for biological activity during iron deposition.

PubMed

Smith, A J B; Beukes, N J; Gutzmer, J; Czaja, A D; Johnson, C M; Nhleko, N

2017-11-01

We document the discovery of the first granular iron formation (GIF) of Archaean age and present textural and geochemical results that suggest these formed through microbial iron oxidation. The GIF occurs in the Nconga Formation of the ca. 3.0-2.8 Ga Pongola Supergroup in South Africa and Swaziland. It is interbedded with oxide and silicate facies micritic iron formation (MIF). There is a strong textural control on iron mineralization in the GIF not observed in the associated MIF. The GIF is marked by oncoids with chert cores surrounded by magnetite and calcite rims. These rims show laminated domal textures, similar in appearance to microstromatolites. The GIF is enriched in silica and depleted in Fe relative to the interbedded MIF. Very low Al and trace element contents in the GIF indicate that chemically precipitated chert was reworked above wave base into granules in an environment devoid of siliciclastic input. Microbially mediated iron precipitation resulted in the formation of irregular, domal rims around the chert granules. During storm surges, oncoids were transported and deposited in deeper water environments. Textural features, along with positive δ 56 Fe values in magnetite, suggest that iron precipitation occurred through incomplete oxidation of hydrothermal Fe 2+ by iron-oxidizing bacteria. The initial Fe 3+ -oxyhydroxide precipitates were then post-depositionally transformed to magnetite. Comparison of the Fe isotope compositions of the oncoidal GIF with those reported for the interbedded deeper water iron formation (IF) illustrates that the Fe 2+ pathways and sources for these units were distinct. It is suggested that the deeper water IF was deposited from the evolved margin of a buoyant Fe 2+ aq -rich hydrothermal plume distal to its source. In contrast, oncolitic magnetite rims of chert granules were sourced from ambient Fe 2+ aq -depleted shallow ocean water beyond the plume. © 2017 John Wiley & Sons Ltd.

LA-ICP-MS analysis of isolated phosphatic grains indicates selective rare earth element enrichment during reworking and transport processes

NASA Astrophysics Data System (ADS)

Auer, Gerald; Reuter, Markus; Hauzenberger, Christoph A.; Piller, Werner E.

2016-04-01

Rare earth elements (REE) are a commonly used proxy to reconstruct water chemistry and oxygen saturation during the formation history of authigenic and biogenic phosphates in marine environments. In the modern ocean REE exhibit a distinct pattern with enrichment of heavy REE and strong depletion in Cerium. Studies of ancient phosphates and carbonates, however, showed that this 'modern' pattern is only rarely present in the geological past. Consequently, the wide range of REE enrichment patterns found in ancient marine phosphates lead to the proposition that water chemistry had to have been radically different in the earth's past. A wealth of studies has already shown that both early and late diagenesis can strongly affect REE signatures in phosphates and severely alter primary marine signals. However, no previous research was conducted on how alteration processes occurring prior to final deposition affect marine phosphates. Herein we present a dataset of multiple LA-ICP-MS measurements of REE signatures in isolated phosphate and carbonate grains deposited in a carbonate ramp setting in the central Mediterranean Sea during the middle Miocene "Monterey event". The phosphates are represented by authigenic, biogenic and detrital grains emplaced in bioclastic grain- to packstones dominated by bryozoan and echinoderm fragments, as well as abundant benthic and planktic foraminifers. The results of 39 grain specific LA-ICP-MS measurements in three discrete rock samples reveals four markedly different REE patterns (normalized to the Post Archean Australian Shale standard) in terms of total enrichment and pattern shape. Analyses of REE diagenesis proxies show that diagenetic alteration affected the samples only to a minor degree. Considering grain shape and REE patterns together indicate that authigenic, detrital and biogenic phosphates have distinct REE patterns irrespective of the sample. Our results show that the observed REE patterns in phosphates only broadly reflect water chemistry under certain well constrained circumstances of primary authigenesis. Are these conditions not met, REE patterns are more likely to reflect complex enrichment processes that likely already started to occur during reworking over geologically relatively short time frames. Similarities in the REE patterns of clearly detrital and biogenic phosphate further suggest that the often observed 'hat-shaped' pattern in biogenic phosphates can easily result from increased middle REE (Neodymium to Holmium) scavenging during taphonomic processes prior to final deposition. Finally, cluster analysis coupled with sedimentological considerations proved a valuable tool for the characterization of REE patterns of phosphates in terms of their formation conditions and depositional history, such as the distinction of phosphates formed in situ from reworked and transported phosphate grains.

Stratigraphy, facies architecture, and palaeoenvironment of Neoproterozoic volcanics and volcaniclastic deposits in Fatira area, Central Eastern Desert, Egypt

NASA Astrophysics Data System (ADS)

Khalaf, Ezz El Din Abdel Hakim

Fatira area in the Central Eastern Desert, Egypt, is a composite terrane consisting of Neoproterozoic volcanics and sediments laid down in submarine to subaerial environment, intruded by voluminous old to young granitic rocks. The various lithofacies of the study area can be grouped in three distinct lithostratigraphic sequences, which are described here in stratigraphic order, from base to top as the Fatira El Beida, Fatira El Zarqa and Gabal Fatira sequences. Each depositional sequence, is intimately related to volcanic activity separated by time intervals of volcanic inactivity, such as marked hiatuses, reworked volcaniclasts, and or turbidite sedimentation. Four submarine facies groups have been recognized within the oldest, folded eruption sequence of Fatira El Beida. The southern part of the study area is occupied by sheet lava (SL), pillow lavas (PL), pillow breccias (PB), and overlying Bouma turbiditic volcaniclastites (VC). The four facies groups of Fatira El Beida sequence occur in a predictable upward-deepening succession, essentially from base to top, an SL-PL-PB-VC stacking pattern. The coeval tholeiitic mafic and felsic volcaniclastic rocks of this sequence indicate an extensional back-arc tectonic setting. The El Beida depositional sequence appears to fit a submarine-fan and slope-apron environment in an intra-arc site. The Fatira El Zarqa sequence involves a large volume of subaerial calc-alkaline intermediate to felsic volcanics and an unconformably overlying siliciclastic succession comprising clast-supported conglomerates (Gm), massive sandstone sheet floods (Sm) and mudstones (FI), together with a lateritic argillite paleosol (P) top formed in an alluvial-fan system. The youngest rock of Gabal Fatira sequence comprises anorogenic trachydacites and rhyolites with locally emergent domes associated with autobrecciation and sill-dyke rock swarms that could be interpreted as feeders and subvolcanic intrusions. Unconformity and lithofacies assemblages define seven events and three unconformity-bounded tectonic stages that record uplift-subsidence cycles in the study area. A proximal-distal relationship has been established within the depositional products, based on the relative dominance of erosional and depositional features.

Applications of ichnology to hydrogeology, with examples from the Cape Fear Formation (Cretaceous), South Carolina

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martin, A.J.; Simones, G.C.

Ichnology, the study of modern and ancient traces left by organisms, has provided supplemental information to geologic subdisciplines such as sedimentology and stratigraphy. The major objective of the authors paper is to emphasize the valuable information that can be conveyed by trace fossils in the investigation of hydrogeologic units. Bioturbation has a net effect of mixing different types and layers of sediments, such as introducing clays into sands and vice versa. This mixing can decrease porosity and permeability of sandy units, thus changing potential aquifers into confining units. For example, a sandy fluvial deposit will contain distinctive nonmarine trace fossils,more » thus defining channel sands that may serve as permeable conduits for ground-water flow. In contrast, a sandy shelf deposit will contain marine trace fossils in a sand body geometry that will be markedly different from aquifers produced in nonmarine environments. Bioturbation also causes geochemical and diagenetic changes in sediments, causing irrigation of previously anoxic sediments and precipitation of ion oxides. The Cretaceous Cape Fear Formation of the Atlantic Coastal Plain, in the subsurface of South Carolina, is presented as an example of a hydrogeologic unit that has been reinterpreted using ichnologic data. Extensive bioturbation caused mixing of clays and sands in Cape Fear sediments, which resulted in the Cape Fear becoming a regional confining system. Trace fossil assemblages indicate a brackish water environment, perhaps estuarine, for the Cape Fear, as opposed to previous interpretations of fluvial and deltaic environments. Bioturbated zones also have significantly more oxidized iron than unbioturbated zones, highlighting potential effects on ground-water quality.« less

Eolian paleotopographic highs as stratigraphic traps: origin and distinction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eschner, T.B.; Kocurek, G.A.

1985-02-01

Significant hydrocarbon accumulations occur where eolian paleotopographic highs are preserved beneath transgressive marine deposits. Paleotopographic highs can represent erosional remnants of an unconformity, or partly preserved eolian dunes, or combinations of both. Paleotopography reflects the extent of modification undergone by eolian units prior to or during transgression. Modification varies between extremes of (1) destruction - where eolian deposits are deeply eroded and the former dunal profile is lost, and (2) preservation - where dunes and interdune areas are preserved nearly intact. The extent of modification that occurs during transgression is controlled primarily by (1) the energy of the transgressing sea,more » (2) the speed of transgression, and (3) the abundance of sand-stabilizing early cements or plants. High-energy seas destroy dunes through persistent erosion by tides and waves and by initiating dune collapse and mass flowage of dune sands. Preservation occurs where quiescent seas flood interdune areas and create shallow to periodically emergent marine environments, such as interdune sabkhas or tidal flats. Gradual filling of interdune areas with shallow marine sediments can fortify and preserve adjacent dunes. These varied processes that interact between marine and eolian environments to create different types of topography are exemplified in ancient eolian-marine sequences of the Western Interior of North America, and preserved Holocene dunes of coastal Australia. Different types of eolian highs can be recognized by analysis of bounding surfaces in outcrop or core. An understanding of eolian-marine processes and environments that create topography allows for prediction of areas of potential stratigraphic traps.« less

Descriptive and grade-tonnage models of volcanogenic manganese deposits in oceanic environments; a modification

USGS Publications Warehouse

Mosier, Dan L.; Page, Norman J

1988-01-01

Four types of volcanogenic manganese deposits, distinguished on the basis of geologic, geochemical, and geophysical characteristics, appear to result from a combination of volcanic and hydrothermal processes related to hot-spring activity in oceanic environments. We compare these four desposit types, here called the Franciscan, Cuban, Olympic Peninsula, and Cyprus, with respect to host rocks, associated rocks, minerals, deposit shape, dimensions, volume, tonnage, grade, and mineral-deposit density (number of deposits per unit area). Franciscan-type deposits occur in obducted oceanic ridge and backarc marginal-basin environments, are associated with chert, shale, and graywacke aroun the margins of mafic volcanic centers, and have a median tonnage of 450 t and median grades of 36 weight percent Mn and less than 5.1 weight percent Fe. Cuban-type deposits occur in island-arc environments, are associated with tuff and limestone around domal structures or intrusions inferred to be volcanic centers, and have a median tonnage of 6,400 t and median grades of 39 weight percent Mn and less than 4.4 weight percent Fe. Olympic Peninsula-type deposits occur in obducted oceanic midplate settings, are associated with argillaceous limestone, argillite, and graywacke around mafic volcanic centers (seamounts or islands), and have a median tonnage of 340 t and median grades of 35 weight percent Mn and less than 6.5 weight percent Fe. Cyprus-type deposits occur in the same tectonic environments as Franciscan type but are associated with basalt, marl, chalk, silt, and chert off the ridge-axis position and have a median tonnage of 41,000 t and median grades of 33 weight percent Fe and 8 weight percent Mn. All these deposits are thin ellipsoids, concordant to the host rocks, but Cyprus-and Cuban-type deposits are larger than Franciscan- and Olympic Peninsula-type deposits. Except for Cyprus-type deposits, which are manganiferous iron (umber) deposits composed of hydrated iron and manganese oxides, all volcanogenic manganese deposits contain manganese oxides, silicates, and carbonates. Mineral-deposit densities, along with grade and tonnage information, are useful for estimating the number, size, andgrades of these deposits in resource assessments.

Lithofacies, depositional environments, regional biostratigraphy and age of the Chitarwata Formation in the Bugti Hills, Balochistan, Pakistan

NASA Astrophysics Data System (ADS)

Métais, Grégoire; Antoine, Pierre-Olivier; Baqri, S. R. Hassan; Crochet, Jean-Yves; De Franceschi, Dario; Marivaux, Laurent; Welcomme, Jean-Loup

2009-02-01

The Oligocene-early Miocene Chitarwata Formation records a critical interval of terrestrial sedimentation that predates the Siwalik deposits on the Potwar Plateau of north-central Pakistan. This Oligocene-early Miocene time interval has long been considered as lacking in the entire Indo-Pakistan region. The Chitarwata Formation is widely exposed in the Sulaiman Range, but has never been described in detail in the Sulaiman Lobe, where the famous fossiliferous strata called 'Bugti Bone Beds' have been known for over a century and half. The Chitarwata Formation represents coastal-delta at the base, and plain and fluvial environments at the top. Lithofacies and sedimentary structures of the Chitarwata Formation in the Bugti area are described in detail, and show a clearly distinct lithologic pattern, different from that reported from the Zinda Pir area. The Chitarwata Formation also records an important transition in the evolution of the drainage systems in the area during the late Paleogene and early Neogene. This transition from the west-flowing paleo-Indus fluvial system to the development of the ancestral Indus drainage system may explain the numerous hiatuses that characterize the Chitarwata Formation. The abundance of fossil mammals from the Chitarwata and overlying Vihowa formation in the Bugti Hills provides critical biochronologic information that sheds new light on biostratigraphic correlation with the Zinda Pir area and for the entire Sulaiman Range.

Sedimentology of the Essaouira Basin (Meskala Field) in context of regional sediment distribution patterns during upper Triassic pluvial events

NASA Astrophysics Data System (ADS)

Mader, Nadine K.; Redfern, Jonathan; El Ouataoui, Majid

2017-06-01

Upper Triassic continental clastics (TAGI: Trias Argilo-Greseux Inferieur) in the Essaouira Basin are largely restricted to the subsurface, which has limited analysis of the depositional environments and led to speculation on potential provenance of the fluvial systems. Facies analysis of core from the Meskala Field onshore Essaouira Basin is compared with tentatively time-equivalent deposits exposed in extensive outcrops in the Argana Valley, to propose a process orientated model for local versus regional sediment distribution patterns in the continuously evolving Moroccan Atlantic rift during Carnian to Norian times. The study aims to unravel the climatic overprint and improve the understanding of paleo-climatic variations along the Moroccan Atlantic margin to previously recognised Upper Triassic pluvial events. In the Essaouira Basin, four facies associations representing a progressive evolution from proximal to distal facies belts in a continental rift were established. Early ephemeral braided river systems are succeeded by a wet aeolian sandflat environment with a strong arid climatic overprint (FA1). This is followed by the onset of perennial fluvial deposits with extensive floodplain fines (FA2), accompanied by a distinct shift in fluvial style, suggesting increase in discharge and related humidity, either locally or in the catchment area. The fluvial facies transitions to a shallow lacustrine or playa lake delta environment (FA3), which exhibits cyclical abandonment. The delta is progressively overlain by a terminal playa with extensive, mottled mudstones (FA4), interpreted to present a return from cyclical humid-arid conditions to prevailing aridity in the basin. In terms of regional distribution and sediment source provenance, paleocurrent data from Carnian to Norian deposits (T5 to T8 member) in the Argana Valley suggest paleoflow focused towards the S and SW, not directed towards the Meskala area in the NW as previously suggested. A major depo-centre for fluvial sediments is instead located in the southern Argana Valley, possibly the Souss Basin. To effectively source the reservoir sandstones found in the Meskala Field, a more local provenance area has hence to be envisaged. Despite this, the direct comparison of the genetic evolution of sedimentary sequences in the Argana Valley and Essaouira Basin shows a similar progression from dominantly arid ephemeral depositional environments to humid perennial sedimentation, returning to prominent arid conditions. This suggests climatic control in both regions, where an enhanced humid signal drives perennial fluvial flow in otherwise arid dominated sequences. On a regional scale, this is suggested to record the impact of strong Triassic pluvial events previously recognised in other basins along the Central Atlantic margin during the Carnian to Norian periods.

Sedimentary architecture of the Shaler outcrop, Gale Crater, Mars: paleoenvironmental and sediment transport implications

NASA Astrophysics Data System (ADS)

Gupta, S.; Edgar, L. A.; Rubin, D. M.; Lewis, K. W.; Kocurek, G.; Anderson, R. B.; Bell, J. F.; Dromart, G.; Edgett, K. S.; Grotzinger, J. P.; Hardgrove, C. J.; Kah, L. C.; Leveille, R. J.; Malin, M.; Mangold, N.; Milliken, R.; Minitti, M. E.; Muller, J.; Rice, M. S.; Rowland, S. K.; Schieber, J.; Stack, K.; Sumner, D. Y.; Team, M.

2013-12-01

Sedimentary rocks are archives of ancient depositional processes and environments on planetary surfaces. Reconstructing such processes and environments requires observations of sedimentary structures and architecture (the large-scale geometry and organisation of sedimentary bedsets). We report the analysis of the distinct Shaler outcrop, a prominent stratified unit located between the Bathurst Inlet outcrop and the floor of Yellowknife bay. The Shaler outcrop is an ~1 m thick stratal unit that spans approximately 30 m outcrop in length, and was examined by Curiosity on sols 120-121 and more recently on sols 309-324. Detailed stereo observations of the outcrop across most of its entire lateral extent were made using Navigation and Mast Cameras. These data permit detailed analysis of stratal geometries, distribution of sedimentary structures, and broad grain size trends. Overall the Shaler outcrop comprises a heterogeneous assemblage of interstratified platy sandstones separated by recessive, likely finer-grained beds. Coarser-grained beds are characterised by decimeter-scale trough cross-bedding. The north-eastern section of the outcrop shows greater abundance of interstratified sandstones and finer-grained beds. The southwestern section is characterised by darker bedsets that are likely coarser grained interstratified with finer-grained sandstones. The darker bedsets appear to comprise stacked trough-cross stratified bedsets. Finer-grained recessive intervals are not apparent in this section. The presence and scale of trough cross-stratification indicates that sediment was transported by the migration of sinuous crested dunes. Bedding geometries indicate sub-critical angles of climb. We examine the large-scale bedset architecture to evaluate the original depositional geometry of the Shaler sedimentary system, and consider its plausible depositional processes and paleoenvironmental setting. Finally, we consider its relationship to the sedimentary succession exposed in the Yellowknife bay region.

Carbon associated nitrate (CAN) in the Ediacaran Johnnie Formation, Death Valley, California and links to the Shuram negative carbon isotope excursion

NASA Astrophysics Data System (ADS)

Dilles, Z. Y. G.; Prokopenko, M. G.; Bergmann, K.; Loyd, S. J.; Corsetti, F. A.; Berelson, W.; Gaines, R. R.

2014-12-01

Nitrogen, a major nutrient of marine primary production whose many redox states are linked through biological processes to O2, may afford better understanding of changes in post-Great Oxidation Event (GOE) environmental redox conditions. Using a novel approach to quantify nitrate content in carbonates, we identified a trend of CAN increase in the late-Proterozoic, including several distinct peaks within a carbonate succession of the Sonora province, Mexico, deposited ~630-500 Ma. The goal of the current study was to investigate CAN variability in the context of the global "Shuram" event, a large negative δ13C excursion expressed in Rainstorm member carbonates of the Johnnie Formation in Death Valley, CA. The lower Rainstorm Member "Johnnie Oolite", a time-transgressive, regionally extensive, shallow dolomitic oolite, was sampled. CAN concentrations ranged from 7.31 to 127.36 nmol/g, with higher values measured toward the base of the bed. This trend held at each sampled locality, along with a tendency towards decreasing CAN with larger magnitude negative δ13C excursions. Modern analog ooids formed in low-latitude marine environments lack CAN, consistent with their formation in low-nitrate waters of the euphotic zone characteristic of the modern ocean nitrogen cycling. In contrast, maximum values within the Johnnie oolite exceed by a factor of five to seven CAN measured in carbonates deposited below the main nitracline in the modern ocean, implying high nitrate content within shallow depositional environments. Johnnie oolite data, broadly consistent with the Sonora sequence findings, may indicate large perturbations in the Ediacaran nitrogen cycle immediately preceding the negative δ13C excursion. The implication of these findings for possible changes in the Ediacaran nitrogen, oxygen and carbon biogeochemical cycling will be further discussed.

Impact of super-distal ash fallout on tropical hydrology and landscape: a case study from the YTT deposits of the Perak river, Malaysia

NASA Astrophysics Data System (ADS)

Gatti, E.; Saidin, M.; Gibbard, P.; Oppenheimer, C.

2011-12-01

The Younger Toba Tuff eruption, approximately 73 ka ago, is the largest known for the Quaternary and its climate, environmental and human consequences are keenly debated (Oppenheimer, 2011).While the distribution (Rose and Chesner, 1987; Rose and Chesner, 1990; Chesner et al., 1991; Schulz et al., 2002; Von Rad et al., 2002) , geochemical properties (Shane et al., 1995; Westgate et al., 1998) and volcanic significance (Rampino and Self, 1982; Rampino and Self, 1993; Rampino and Ambrose, 2000; Oppenheimer, 2002; Mason et al., 2004)of the YTT have been widely studied, few attention has been given to the significance of the distal volcanic ash deposits within their receiving basin context. Although several studies exist on the impact of pyroclastic flows on proximal rivers and lakes (Collins and Dunne, 1986; Thompson et al., 1986; Hayes et al., 2002; Németh and Cronin, 2007), only few address the issues of the dynamic of preservation of super-distal fine ash deposits in rivers (also due to the lack of direct data on super-eruptions). It has also been demonstrated that models of the styles and timing of distal volcanoclastic re-sedimentation are more complicated than those developed for proximal settings of stratovolcanoes (Kataoka et al., 2009). We present an analysis of the taphonomy (intended as accumulation and preservation) of distal volcanic ash in fluvial and lacustrian contexts in newly discovered Toungest Toba Tuff sites in the Lenggong valley, western Peninsular Malaysia. The paper aims to characterise the nature of distal tephras in fluvial environments towards a stratigraphic distinction between primary ash and secondary ash, characterisation of the pre-ash fall receiving environment in term of fluvial dynamic and landscape morphology, and assessment of the time of recovery.

Sedimentological characterization of flood-tidal delta deposits in the Sego Sandstone, subsidence analysis in the Piceance Creek Basin, and uranium-lead geochronology (NW Colorado, USA)

NASA Astrophysics Data System (ADS)

York, Carly C.

The Sego Sandstone located in western Colorado is a member of the Upper Cretaceous Mesaverde Group and is considered an analogue of the Canadian heavy oil sands. Deposition of the Sego Sandstone occurred during the Upper Campanian (~78 Ma) at the end of the Sevier Orogeny and the beginning of the Laramide Orogeny on the western edge of the Cretaceous Interior Seaway. Although regional studies have detailed time equivalent deposits in the Book Cliffs, UT, the tidally influenced and marginal marine lithofacies observed north of Rangely, CO are distinctly different from the dominately fluvial and tidally-influenced delta facies of Book Cliff outcrops to the southwest. This study characterized flood-tidal delta deposits within the Sego Sandstone, the subsidence history of the Upper Cretaceous sedimentary rocks within the present day Piceance Creek Basin in NW Colorado, and the detrital zircon signal and oldest depositional age of the Sego Sandstone. The goals of this study are to (i) identify relative controls on reservoir characteristics of marginal marine deposits, specifically in flood-tidal delta deposits; (ii) identify the possible mechanisms responsible for subsidence within the present day Piceance Creek Basin during the Late Cretaceous; and (iii) better constrain the provenance and maximum depositional age of the Sego Sandstone. In this study I compared grain size diameter, grain and cement composition, and the ratio of pore space/cement from thin sections collected in tidal, shoreface, and flood-tidal delta facies recognized along detailed measured stratigraphic sections. This analysis provides a detailed comparison between different depositional environments and resultant data showed that grain size diameter is different between tidal, shoreface, and flood-tidal delta facies. Identifying the subsidence mechanisms affecting the Piceance Creek Basin and sediment source of the Late Cretaceous sediments, on the other hand, is important for evaluation of controls on basin filling. Additionally, U-Pb analysis better constrains youngest depositional age for the Sego Sandstone in northwestern Colorado to 76 Ma years old, where previously constraints have been based on stratigraphic relationships and biostratigraphy in eastern Utah and southeastern Colorado.

Oligocene Fluvio-Deltaic Depositional Environments Salin Sub-Basin, Central Myanmar

NASA Astrophysics Data System (ADS)

Gough, A.; Hall, R.

2017-12-01

A recent increase in accessibility for research in Myanmar has allowed rapid advancements in the understanding of the geology of the country. Evolving depositional environments can be reconstructed in largely unstudied Oligocene deposits of the Salin sub-basin, of the Central Myanmar Basin. Data has been collected through a fieldwork campaign to target well-exposed sediments along the western margin of the basin. The studied outcrops span approximately one hundred kilometres from north to south, and a series of sedimentary logs, palaeocurrent data, 2D panel diagrams, and samples for petrographical analysis have been collected and interpreted. The Oligocene formations studied include the Shwezetaw, Paduang, and Okhmintaung, each of which show a broadly southwards-trending fluvio-deltaic environment of deposition. Towards the north, the lower Rupelian Shwezetaw Formation comprises thick fluviatile sandstones which grade southwards through macrotidal-dominated fluvio-deltaic interbedded siltstones and rare sandstones, into marine sandstones. Overlying this, the upper Rupelian Paduang Formation grades rapidly from rare fluvial sandstones towards the north of the basin into deltaic and marine interbedded sandstones and siltstones to the south. This formation is more marine in nature, suggesting a minor transgression throughout the lower Oligocene. By the time of deposition of the Okhmintaung Formation in the Chattian the observed deposits solely represent a tidally-influenced deltaic depositional environment, with very little temporal variation, suggesting a stable sea level. Despite the relatively unchanging depositional environment, the formations are approximately 4000 m thick, suggesting that sedimentation kept pace with relatively rapid subsidence. This current study, which will combine depositional environment reconstruction, provenance, and sediment routing analysis, will provide important insights into both the tectonic setting and the huge sediment accumulation of the poorly understood Central Myanmar Basin.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jaramillo, C.A.; Pardo-Trujillo, A.; Rueda, M.

A palynological study of the Cerrejon Formation was conducted in order to date the formation and understand the floristic composition and diversity of a Paleocene tropical site. The Cerrejon Formation outcrops in the Cerrejon Coal Mine, the largest open cast coal mine in the world. Two cores (725 m) were provided by Carbones del Cerrejon LLC for study. Two hundred samples were prepared for palynology, and at least 150 palynomorphs were counted per sample where possible. Several statistical techniques including rarefaction, species accumulation curves, detrended correspondence analysis, and Anosim were used to analyze the floristic composition and diversity of themore » palynofloras. Palynomorph assemblages indicate that the age of the Cerrejon Formation and the overlying Tabaco Formation is Middle to Late Paleocene (ca. 60-58 Ma). Major structural repetitions were not found in the Cerrejon Formation in the Cerrejon coal mine, and there is little floral variation throughout. The floral composition, diversity, and lithofacies do not change significantly. Lithofacies associations and floral composition indicate deposition fluctuating from an estuarine-influenced coastal plain at the base to a fluvial-influenced coastal plain at the top. There are, however, significant differences in the composition and diversity of coal and siliciclastic samples. Coal palynofloras have fewer morphospecies, and a distinct and more homogeneous floral assemblage compared to assemblages from the intervening sisliciclastic strata, suggesting that tropical swampy environments supported fewer plant species and had a distinct vegetation adapted to permanently wet environments.« less

Mineralogy and Organic Geochemistry of Acid Sulfate Environments from Valles Caldera, New Mexico: Habitability, Weathering and Biosignatures

NASA Astrophysics Data System (ADS)

Vogel, M. B.; Des Marais, D. J.; Jahnke, L. L.; Kubo, M.

2009-12-01

We report on the mineralogy, organic preservation potential and habitability of sulfate deposits in acid sulfate volcanic settings at Valles Caldera, New Mexico. Fumaroles and acidic springs are potential analogs for aqueous environments on Mars and may offer insights into habitability of sulfate deposits such as those at Meridiani Planum. Sulfates recently detected on Mars are posited to have formed from fluids derived from basaltic weathering and igneous volatile input, ultimately precipitating from acidic brines subjected to desiccation and freeze-thaw cycles (McClennan and Grotzinger, 2008). Key issues concerning martian sulfate deposits are their relationship to aqueous clay deposits, and whether or not specific sulfates deposits represent former habitable environments (see Soderblum and Bell, 2008; Tosca et al., 2008). Modern terrestrial volcanic fumaroles and hot springs precipitate various Ca-, Mg- and Fe- sulfates along with clays, and can help clarify whether certain acid sulfate mineral assemblages reflect habitable environments. Valles caldera is a resurgent caldera last active in the Pleistocene (1.4 - 1.0 Ma) that hosts several active fumaroles and over 40 geothermal exploration wells (see Goff, 2009). Fumaroles and associated mudpots and springs at Valles range from pH < 1 to 3, and affect argillic alteration upon rhylolitic tuffs and sedimentary deposits (Charles et al., 1986). We identified assemblages containing gypsum, quartz, Al-sulfates, elemental sulfur, clays and other minerals using XRD and SEM-EDS. Our previous research has shown that sulfates from different marine depositional environments display textural and morphological traits that are indicative of biological influence, or specific conditions in the depositional environments (Vogel et al., 2009). Gypsum crystals that develop in the presence of microbial biofilms in marine environments may have distorted crystal morphologies, biofilm - associated dissolution features, and accessory carbonate minerals. Gypsum from Valles Caldera fumaroles develops in the absence of microbial biofilms and differs from biologically influenced marine gypsum in terms of is highly prismatic morphology, lack of texture, and association with clays, and other sulfates. Studies of Valles gypsum crystals therefore support the uniqueness of the putative morphological biosignatures in marine gypsum. We also assayed organic matter from fumarole encrustations to understand how low pH and sulfate content may discriminate against or enhance preservation of specific classes of organic compounds in acid sulfate environments. Similar to gypsiferous marine environments, organics are characterized by abundant organosulfur complexes. Long chain alkanes (> nC22) are abundant from acid sulfate environments. As with hypersaline marine depositional environments, sulfidation appears to be a major diagenetic pathway for organic matter in acid sulfate environments.

ATMOSPHERIC MERCURY SIMULATION USING THE CMAQ MODEL: FORMULATION DESCRIPTION AND ANALYSIS OF WET DEPOSITION RESULTS

EPA Science Inventory

The Community Multiscale Air Quality (CMAQ) modeling system has recently been adapted to simulate the emission, transport, transformation and deposition of atmospheric mercury in three distinct forms; elemental mercury gas, reactive gaseous mercury, and particulate mercury. Emis...

Lacustrine deposits in rifted deep basins of Yellow Sea

DOE Office of Scientific and Technical Information (OSTI.GOV)

Han, J.H.

1985-02-01

The central Yellow Sea is a typical intracratonic rifted basin that consists of 4 major depressions bounded by aligned listric faults along horst blocks of uplifted basement (Kunsan, West Kunsan, Yellow Sea sub-basins, and Central Trough). The depressions are half grabens caused by pull-apart extensional stresses. Core analysis and micropaleotologic study indicate that more than 5 km of lacustrine sediments were accumulated in the central part of the West Kunsan basin. Two distinctive sedimentary successions are recognized in the core descriptions: alternation of reddish-brown siltstones and sandstones containing evaporites and marlstones, and an overlying progradational sequence including minor limestone bedsmore » in the lower part of the sequence. The progradational sequence is interpreted as lacustrine deltaic deposits. Abundant palynofloral occurrence of freshwater green algae, Pediastrum, and absence of marine fauna such as dinoflagellates are also supporting evidence for a lacustrine environment. The lithofacies and tectonic framework of the Yellow Sea are very similar to those of Cretaceous lacustrine sediments of the Korea Peninsula onshore and Pohai coastal basin in China.« less

Beyond the obvious limits of ore deposits: The use of mineralogical, geochemical, and biological features for the remote detection of mineralization

USGS Publications Warehouse

Kelley, D.L.; Kelley, K.D.; Coker, W.B.; Caughlin, B.; Doherty, M.E.

2006-01-01

Far field features of ore deposits include mineralogical, geochemical, or biological attributes that can be recognized beyond the obvious limits of the deposits. They can be primary, if formed in association with mineralization or alteration processes, or secondary, if formed from the interaction of ore deposits with the hydrosphere and biosphere. This paper examines a variety of far field features of different ore deposit types and considers novel applications to exploration and discovery. Primary far field features include mineral and rock chemistry, isotopic or element halos, fluid pathways and thermal anomalies in host-rock sequences. Examples include the use of apatite chemistry to distinguish intrusive rocks permissive for iron oxide copper gold (IOCG) and porphyry deposits; resistate mineral (e.g., rutile, tourmaline) chemistry in exploration for volcanogenic massive sulfide (VMS), orogenic gold, and porphyry deposits; and pyrite chemistry to vector toward sedimentary exhalative (sedex) deposits. Distinctive whole-rock geochemical signatures also can be recognized as a far field feature of porphyry deposits. For example, unique Sr/Y ratios in whole-rock samples, used to distinguish barren versus fertile magmas for Cu mineralization, result from the differentiation of oxidized hydrous melts. Anomalous concentrations of halogen elements (Cl, Br, and I) have been found for distances of up to 200 m away from some mineralized centers. Variations in isotopic composition between ore-bearing and barren intrusions and/or systematic vertical and lateral zonation in sulfur, carbon, or oxygen isotope values have been documented for some deposit types. Owing to the thermal aureole that extends beyond the area of mineralization for some deposits, detection of paleothermal effects through methods such as conodont alteration indices, vitrinite or bitumen reflectance, illite crystallinity, and apatite or zircon thermochronology studies also can be valuable, particularly for deposits with a low-temperature thermal history. A number of newly investigated secondary far field features include the development of reduced columns by electrochemical processes in transported overburden, geochemical dispersion related to the expulsion of groundwater from tectonic and seismic compression, dispersion of vapor above ore deposits, and geochemical dispersion related to biological processes. Redox gradients have been found between underlying reduced and overlying oxidized environments associated with sulfide bodies, which result in mass transfer through electro-chemical dispersion. Recent studies have characterized the pH, oxidation-reduction potential (ORP), and self potential (SP) in overburden overlying sulfide-hosted gold and VMS deposits. Lateral migration of metals in groundwater is well understood from normal groundwater flow, but the processes responsible for vertical mass transfer of groundwater and its dissolved components have been recognized only recently. One process, termed cyclical dilatancy pumping, expels groundwater during and after earthquake events, which can cause the redistribution of metals around deposits in some environments. Soil gases are of interest owing to their high degree of mobility through the vadose zone in transported overburden. Numerous soil gas species (CO2, O2, Hg, Rn, He, sulfur compounds, and light hydrocarbons) have been measured and interpreted as diagnostic of some buried mineral deposits, and some evidence suggests a possible link between vapor dispersion and metal enrichment in soil. Geochemical enrichment in plant material and soils through successive growth-death cycles is well established, but the important role of microorganisms is now increasingly evident. Microorganisms significantly enhance the kinetics of sulfide oxidation and influence the distribution of metals around ore deposits. The presence of metal-resistant bacteria and enhanced concentrations of sulfate-reducing bacteria in exotic overburd

Electrochemical characterization of cerium-based conversion coatings on aluminum alloy 7075-T6

NASA Astrophysics Data System (ADS)

Joshi, Simon

This research used electrochemical techniques to characterize the deposition and corrosion protection behavior of cerium-based conversion coatings on Al 7075-T6. Alkaline activation decreased native oxide impedance (5.9 kO-cm2) by ˜25% promoting deposition of 250--500 nm coatings. Activation in NaOH solutions deposited coatings with large cracks and craters, whereas Na2CO3 activation resulted in uniform coatings, i.e., fewer cracks and almost no craters. Uniformly deposited coatings exhibited better cathodic inhibition and higher impedance (˜200 kO-cm 2) than on NaOH activated substrates (˜100 kO-cm 2). Subsurface crevices, caused by Cl- and H 2O2 in the deposition solution, were found under large cracks and craters. Thus, Na2CO3 activation produced fewer subsurface crevices. To reduce subsurface crevice formation, Ce(NO3) 3 and CeCl3 were used in different ratios. Coatings made using 100% Ce(NO3)3 solutions were ˜60 nm thick without subsurface crevices, but the coatings offered little corrosion protection. Despite formation of subsurface crevices, Cl- was necessary as impedance increased linearly with Cl- concentration in the deposition solution. To characterize the different non-uniform features of the coatings, microelectrochemical testing was performed and it showed three distinct regions: active, intermediate, and passive. Humidity experiments were performed to understand the effect of moisture during salt spray testing and showed an increase in coating impedance by making the exposed substrate oxide more passive. However, this passive oxide could not provide corrosion resistance in a chloride environment. Dissolution studies showed that cerium migration was only possible at pH ≤2. Overall, deposition of uniform 250--500 nm thick outings was essential to make it an effective barrier to Cl - attach and prevent subsurface crevices on Al 7075-T6.

Paleocene-eocene lignite beds of southwest Alabama: Parasequence beds in highstand systems tracts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mancini, E.A.; Tew, B.H.; Carroll, R.E.

1993-09-01

In southwest Alabama, lignite beds are present in at least four stratigraphic intervals that span approximately 8 m.y. of geologic time. Lignite is found in the Paleocene Oak Hill Member and Coal Bluff Member of the Naheola Formation of the Midway Group and the Paleocene Tuscahoma Sand and the Eocene Hatchetigbee Formation of the Wilcox Group. Lignite beds range in thickness from 0.5 to 11 ft and consist of 32-53% moisture, 13-39% volatile matter, 4-36% fixed carbon, and 5-51% ash. These Paleocene and Eocene lignite beds occur as parasequence deposits in highstand systems tracts of four distinct third-order depositional sequences.more » The lignite beds are interpreted as strata within highstand systems tract parasequences that occur in mud-dominated regressive intervals. Lignite beds were deposited in coastal marsh and low-lying swamp environments as part of deltaic systems that prograded into southwestern Alabama from the west. As sediment was progressively delivered into the basin from these deltas, the effects of relative sea level rise during an individual cycle were overwhelmed, producing a net loss of accommodation and concomitant overall basinward progradation of the shoreline (regression). Small-scale fluctuations in water depth resulting from the interaction of eustasy, sediment yield, and subsidence led to cyclical flooding of the low-lying coastal marshes and swamps followed by periods of progradational and regression. Highstand systems tract deposition within a particular depositional sequence culminated with a relative sea level fall that resulted in a lowering of base level and an abrupt basinward shift in coastal onlap. Following sea level fall and the subsequent accumulation of the lowstand deposits, significant relative sea level rise resulted in the marine inundation of the area previously occupied by coastal marshes and swamps and deposition of the transgressive systems tract of the overlying sequence.« less

Trace elements in magnetite from massive iron oxide-apatite deposits indicate a combined formation by igneous and magmatic-hydrothermal processes

NASA Astrophysics Data System (ADS)

Knipping, Jaayke L.; Bilenker, Laura D.; Simon, Adam C.; Reich, Martin; Barra, Fernando; Deditius, Artur P.; Wälle, Markus; Heinrich, Christoph A.; Holtz, François; Munizaga, Rodrigo

2015-12-01

Iron oxide-apatite (IOA) deposits are an important source of iron and other elements (e.g., REE, P, U, Ag and Co) vital to modern society. However, their formation, including the namesake Kiruna-type IOA deposit (Sweden), remains controversial. Working hypotheses include a purely magmatic origin involving separation of an Fe-, P-rich, volatile-rich oxide melt from a Si-rich silicate melt, and precipitation of magnetite from an aqueous ore fluid, which is either of magmatic-hydrothermal or non-magmatic surface or metamorphic origin. In this study, we focus on the geochemistry of magnetite from the Cretaceous Kiruna-type Los Colorados IOA deposit (∼350 Mt Fe) located in the northern Chilean Iron Belt. Los Colorados has experienced minimal hydrothermal alteration that commonly obscures primary features in IOA deposits. Laser ablation-inductively coupled plasma-mass spectroscopy (LA-ICP-MS) transects and electron probe micro-analyzer (EPMA) wavelength-dispersive X-ray (WDX) spectrometry mapping demonstrate distinct chemical zoning in magnetite grains, wherein cores are enriched in Ti, Al, Mn and Mg. The concentrations of these trace elements in magnetite cores are consistent with igneous magnetite crystallized from a silicate melt, whereas magnetite rims show a pronounced depletion in these elements, consistent with magnetite grown from an Fe-rich magmatic-hydrothermal aqueous fluid. Further, magnetite grains contain polycrystalline inclusions that re-homogenize at magmatic temperatures (>850 °C). Smaller inclusions (<5 μm) contain halite crystals indicating a saline environment during magnetite growth. The combination of these observations are consistent with a formation model for IOA deposits in northern Chile that involves crystallization of magnetite microlites from a silicate melt, nucleation of aqueous fluid bubbles on magnetite surfaces, and formation and ascent of buoyant fluid bubble-magnetite aggregates. Decompression of the fluid-magnetite aggregate during ascent along regional-scale transcurrent faults promotes continued growth of the magmatic magnetite microlites from the Fe-rich magmatic-hydrothermal fluid, which manifests in magnetite rims that have trace element abundances consistent with growth from a magmatic-hydrothermal fluid. Mass balance calculations indicate that this process can leach and transport sufficient Fe from a magmatic source to form large IOA deposits such as Los Colorados. Furthermore, published experimental data demonstrate that a saline magmatic-hydrothermal ore fluid will scavenge significant quantities of metals such as Cu and Au from a silicate melt, and when combined with solubility data for Fe, Cu and Au, it is plausible that the magmatic-hydrothermal ore fluid that continues to ascend from the IOA depositional environment can retain sufficient concentrations of these metals to form iron oxide copper-gold (IOCG) deposits at lateral and/or stratigraphically higher levels in the crust. Notably, this study provides a new discrimination diagram to identify magnetite from Kiruna-type deposits and to distinguish them from IOCG, porphyry and Fe-Ti-V/P deposits, based on low Cr (<100 ppm) and high V (>500 ppm) concentrations.

Descriptive and geoenvironmental model for Co-Cu-Au deposits in metasedimentary rocks: Chapter G in Mineral deposit models for resource assessment

USGS Publications Warehouse

Slack, John F.; Johnson, Craig A.; Causey, J. Douglas; Lund, Karen; Schulz, Klaus J.; Gray, John E.; Eppinger, Robert G.; Slack, John F.

2013-01-01

Additional geologically and compositionally similar deposits are known, but have average Co grades less than 0.1 percent. Most of these deposits contain cobalt-rich pyrite and lack appreciable amounts of distinct Co sulfide and (or) sulfarsenide minerals. Such deposits are not discussed in detail in the following sections, but these deposits may be revelant to the descriptive and genetic models presented below. Examples include the Scadding Au-Co-Cu deposit in Ontario, Canada; the Vähäjoki Co-Cu-Au deposit in Finland; the Tuolugou Co-Au deposit in Qinghai Province, China; the Lala Co-Cu-UREE deposit in Sichuan Province, China; the Guelb Moghrein Cu-Au-Co deposit in Mauritania; and the Great Australia Co-Cu, Greenmount Cu-Au-Co, and Monakoff Cu-Au-Co-UAg deposits in Queensland, Australia. Detailed information on these deposits is presented in appendix 2.

Paleo-Environment and C-14 Dating: The Key to the Depositional Age of the Tha Chang and Related Sand Pits, Northeastern Thailand

NASA Technical Reports Server (NTRS)

Putthapiban, P.; Zolensky, M.; Jull, T.; Demartino, M.; Salyapongse, S.

2012-01-01

Tha Chang sand pits, Nakhon Ratchasima Province and many other sand pits in the area adjacent to the Mun River are characterized by their fluviatile environment in association with mass wasting deposits, along the paleo-river channel and the flood plain of the Mun River. Sediments of these deposits are characterized by clasts of various rock types especially the resistant ones with frequent big tree trunks, logs and wood fragments in different sizes and various stages of transformation from moldering stage to lignification and petrification. Widespread pyritization of the lower horizon suggests strongly reducing environment during burial. The Tha Chang deposits have been received much attention from geoscientists especially paleontologist communities, as they contain fragments of some distinct vertebrate species such as Stegadon sp., hominoid primate, rhinoceros Aceratherium and others. Based on the associated mammal fauna and hominoid fossils, the late Miocene ( 9 - 6 Ma) was given for the time of deposition of this sand and gravel unit. Some other reports believed that sediments and materials of these sand and gravel quarries (pits) were deposited by high-energy flood pulses contemporaneous with the tektites forming event during mid-Pleistocene at c. 0.8 Ma. Interpretation from Palynostratigraphical study suggested that the lower horizon of Tha Chang sand pit was deposited during Pliocene/Pleistocene period and the upper horizons are Pleistoncene/Holocene. It is crystal clear that all the fluviatile sediments including tektites and almost all fossil fragments being deposited in these sand pits were, likely a multiple times reworked materials. Only some old bamboo trees, some old crowling trees and fossils grasses observed on the old river bank are considered in situ. C-14 dating of 5 old wood specimens from Tha Chang Sand Pits, 15 old wood specimens from Chumpuang Sand Pits and one sample of old pottery from a Chumpuang Sand Pit were carried out in the NSF- Arizona AMS Laboratory. Although, there is no sharp boundary between the unconsolidated sedimentary horizons in the pits, C-14 ages obtained from the Tha Chang vary from 34,340 BP at the middle horizon (approx 10 m below ground zero) to >49,900 BP at the lower horizon with unknown basal formation (highly pyritized zone approx 20 - 25 m below ground zero). The ages for the Chumpuang vary from 41,700 BP, >45,900 BP and >49,900 BP from the upper most to the lower most of a broad horizon (approx 8 m to approx 12 m below ground zero). The C-14 age of the pottery collected from layer approximately 5 m below ground zero is 2,514 BP. The nature of fluviatile together with occasional mass wasting characteristics of all sand pits studies suggest the relatively faster depositional rate of the lower horizon which involved more flooding and mass wasting deposits than those of the upper horizons. The apparent of some mixing of the wood ages may indicate reworking and lag deposits nature of the area. The depositional rate of the upper most sand and soil horizon (5 m thick) is approximately 1 m per 500 years which mean both erosion and deposition had played a significant role during that time period. In term of the true age of the formation, we argue that since most of the materials deposited are reworked materials, all ages obtained from fossil fragments could not be the age of sand and gravel formation. Furthermore, the maximum age of all the tektite bearing horizons cannot be older than 0.8 Ma. The oldest C-14 age of 49,900 BP is interpreted as the minimum age of the Tha Chang and related sand pits formation when geomorphology of the area was a lot more hilly and much higher gradient than that of the present day.

South polar residual cap of Mars: Features, stratigraphy, and changes

NASA Astrophysics Data System (ADS)

Thomas, P. C.; Malin, M. C.; James, P. B.; Cantor, B. A.; Williams, R. M. E.; Gierasch, P.

2005-04-01

The south residual polar cap of Mars, rich in CO 2 ice, is compositionally distinct from the north residual cap which is dominantly H 2O ice. The south cap is also morphologically distinct, displaying a bewildering variety of depressions formed in thin layered deposits, which have been observed to change by scarp retreat over an interval of one Mars year (Malin et al., 2001, Science 294, 2146-2148). The climatically sensitive locale of the residual caps suggests that their behavior may help in the interpretation of recent fluctuations or repeatability of the Mars climate. We have used Mars Global Surveyor Mars Orbiter Camera (MOC) images obtained in three southern summers to map the variety of features in the south residual cap and to evaluate changes over two Mars years (Mars y). The images show that there are two distinct layered units which were deposited at different times separated by a period of degradation. The older unit, ˜10 m thick, has layers approximately 2 m thick. The younger unit has variable numbers of layers, each ˜1 m thick. The older unit is eroding by scarp retreat averaging 3.6 m/Mars y, a rate greater than the retreat of 2.2 m/Mars y observed for the younger unit. The rates of scarp retreat and sizes of the different types of depressions indicate that the history of the residual cap has been short periods of deposition interspersed with longer erosional periods. Erosion of the older unit probably occupied ˜100-150 Mars y. One layer may have been deposited after the Mariner 9 observations in 1972. Residual cap layers appear to differ from normal annual winter deposits by having a higher albedo and perhaps by having higher porosities. These properties might be produced by differences in the depositional meteorology that affect the fraction of high porosity snow included in the winter deposition.

Cerebral vascular amyloid seeds drive amyloid β-protein fibril assembly with a distinct anti-parallel structure

PubMed Central

Xu, Feng; Fu, Ziao; Dass, Sharmila; Kotarba, AnnMarie E.; Davis, Judianne; Smith, Steven O.; Van Nostrand, William E.

2016-01-01

Cerebrovascular accumulation of amyloid β-protein (Aβ), a condition known as cerebral amyloid angiopathy (CAA), is a common pathological feature of patients with Alzheimer's disease. Familial Aβ mutations, such as Dutch-E22Q and Iowa-D23N, can cause severe cerebrovascular accumulation of amyloid that serves as a potent driver of vascular cognitive impairment and dementia. The distinctive features of vascular amyloid that underlie its unique pathological properties remain unknown. Here, we use transgenic mouse models producing CAA mutants (Tg-SwDI) or overproducing human wild-type Aβ (Tg2576) to demonstrate that CAA-mutant vascular amyloid influences wild-type Aβ deposition in brain. We also show isolated microvascular amyloid seeds from Tg-SwDI mice drive assembly of human wild-type Aβ into distinct anti-parallel β-sheet fibrils. These findings indicate that cerebrovascular amyloid can serve as an effective scaffold to promote rapid assembly and strong deposition of Aβ into a unique structure that likely contributes to its distinctive pathology. PMID:27869115

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lü, B.; Münger, E. P.; Sarakinos, K.

The morphology and physical properties of thin films deposited by vapor condensation on solid surfaces are predominantly set by the processes of island nucleation, growth, and coalescence. When deposition is performed using pulsed vapor fluxes, three distinct nucleation regimes are known to exist depending on the temporal profile of the flux. These regimes can be accessed by tuning deposition conditions; however, their effect on film microstructure becomes marginal when coalescence sets in and erases morphological features obtained during nucleation. By preventing coalescence from being completed, these nucleation regimes can be used to control microstructure evolution and thus access a largermore » palette of film morphological features. Recently, we derived the quantitative criterion to stop coalescence during continuous metal vapor flux deposition on insulating surfaces—which typically yields 3-dimensional growth—by describing analytically the competition between island growth by atomic incorporation and the coalescence rate of islands [Lü et al., Appl. Phys. Lett. 105, 163107 (2014)]. Here, we develop the analytical framework for entering a coalescence-free growth regime for metal vapor deposition on insulating substrates using pulsed vapor fluxes, showing that there exist three distinct criteria for suppressing coalescence that correspond to the three nucleation regimes of pulsed vapor flux deposition. The theoretical framework developed herein is substantiated by kinetic Monte Carlo growth simulations. Our findings highlight the possibility of using atomistic nucleation theory for pulsed vapor deposition to control morphology of thin films beyond the point of island density saturation.« less

In Situ Biomineralization and Particle Deposition Distinctively Mediate Biofilm Susceptibility to Chlorine

PubMed Central

Li, Xiaobao; Chopp, David L.; Russin, William A.; Brannon, Paul T.; Parsek, Matthew R.

2016-01-01

Microbial biofilms and mineral precipitation commonly co-occur in engineered water systems, such as cooling towers and water purification systems, and both decrease process performance. Microbial biofilms are extremely challenging to control and eradicate. We previously showed that in situ biomineralization and the precipitation and deposition of abiotic particles occur simultaneously in biofilms under oversaturated conditions. Both processes could potentially alter the essential properties of biofilms, including susceptibility to biocides. However, the specific interactions between mineral formation and biofilm processes remain poorly understood. Here we show that the susceptibility of biofilms to chlorination depends specifically on internal transport processes mediated by biomineralization and the accumulation of abiotic mineral deposits. Using injections of the fluorescent tracer Cy5, we show that Pseudomonas aeruginosa biofilms are more permeable to solutes after in situ calcite biomineralization and are less permeable after the deposition of abiotically precipitated calcite particles. We further show that biofilms are more susceptible to chlorine killing after biomineralization and less susceptible after particle deposition. Based on these observations, we found a strong correlation between enhanced solute transport and chlorine killing in biofilms, indicating that biomineralization and particle deposition regulate biofilm susceptibility by altering biocide penetration into the biofilm. The distinct effects of in situ biomineralization and particle deposition on biocide killing highlight the importance of understanding the mechanisms and patterns of biomineralization and scale formation to achieve successful biofilm control. PMID:26944848

A contribution to regional stratigraphic correlations of the Afro-Brazilian depression - The Dom João Stage (Brotas Group and equivalent units - Late Jurassic) in Northeastern Brazilian sedimentary basins

NASA Astrophysics Data System (ADS)

Kuchle, Juliano; Scherer, Claiton Marlon dos Santos; Born, Christian Correa; Alvarenga, Renata dos Santos; Adegas, Felipe

2011-04-01

The Dom João Stage comprises an interval with variable thickness between 100 and 1200 m, composed of fluvial, eolian and lacustrine deposits of Late Jurassic age, based mainly on the lacustrine ostracod fauna (although the top deposits may extend into the Early Cretaceous). These deposits comprise the so-called Afro-Brazilian Depression, initially characterized as containing the Brotas Group of the Recôncavo Basin (which includes the Aliança and the Sergi Formations) and subsequently extended into the Tucano, Jatobá, Camamu, Almada, Sergipe, Alagoas and Araripe Basins in northeastern Brazil, encompassing the study area of this paper. The large occurrence area of the Dom João Stage gives rise to discussions about the depositional connectivity between the basins, and the real extension of sedimentation. In the first studies of this stratigraphic interval, the Dom João Stage was strictly associated with the rift phase, as an initial stage (decades of 1960-70), but subsequent analyses considered the Dom João as an intracratonic basin or pre-rift phase - without any relation to the active mechanics of a tectonic syn-rift phase (decades of 1980-2000). The present work developed an evolutionary stratigraphic and tectonic model, based on the characterization of depositional sequences, internal flooding surfaces, depositional systems arrangement and paleoflow directions. Several outcrops on the onshore basins were used to build composite sections of each basin, comprising facies, architectural elements, depositional systems, stratigraphic and lithostratigraphic frameworks, and paleocurrents. In addition to that, over a hundred onshore and offshore exploration wells were used (only 21 of which are showed) to map the depositional sequences and generate correlation sections. These show the characteristics and relations of the Dom João Stage in each studied basin, and they were also extended to the Gabon Basin. The results indicate that there were two main phases during the Dom João Stage, in which distinctive sedimentary environments were developed, reflecting depositional system arrangements, paleoflow directions were diverse, and continuous or compartmented basins were developed.

Flashy Water and Sediment Delivery to Fluvial Megafan andFan Delta Systems on Opposing Shorelines of an Early Eocene Lake

NASA Astrophysics Data System (ADS)

Jones, E. R.; Plink-Bjorklund, P.

2015-12-01

Flashy delivery of water and sediment had distinct effects on the process of deposition in coeval fluvial megafan and fan delta deposits on opposing shorelines of a paleolake that occupied the Uinta Basin throughout the Eocene. The Tertiary Uinta Basin was an asymmetric continental interior basin with a steep northern margin, adjacent to the block uplift controlling basin subsidence, and a low gradient southern margin. A ~140 km wide fluvial megafan with catchments as far as ~750 km away occupied the southern margin of the lacustrine basin. Within this megafan system, fluvial deposits contain within-channel continental bioturbation and paleosol development on bar accretion surfaces that are evidence of prolonged periods of groundwater flow or channel abandonment. These are punctuated by channel fills exhibiting a suite of both high-deposition rate and upper flow regime sedimentary structures that were deposited by very rapid suspension-fallout during seasonal to episodic river flooding events. A series of small (~8 km wide) and proximally sourced fan deltas fed sediment into the steeper northern margin of the lacustrine basin. 35-50% of the deposits in the delta plain environment of these fan deltas are very sandy debris flows with as low as 5% clay and silt sized material. Detrital zircon geochronology shows that these fan deltas were tapping catchments where mostly unconsolidated Cretaceous sedimentary cover and thick Jurassic eolianites were being eroded. A combination of flashy precipitation, arid climate, catchments mantled by abundant loose sand-sized colluvium, and steep depositional gradients promoted generation of abundant very sandy (5-10% clay and silt sized material) debris flows. In this way, the Wasatch and Green River Formations in the Uinta Basin, Utah, U.S.A. gives us two very different examples of how routing flashy water and sediment delivery (associated with pulses of hyperthermal climate change during the Early Eocene) through different depositional systems produced unique processes of deposition, and also gives us an opportunity to isolate the effects of other variables (e.g. sediment caliber, system gradient, catchment size) that can modulate the flashy precipitation signal in stratigraphy.

[Dense deposit nephropathy: a peculiar variant of glomerulonephritis or a distinct disease entity (author's transl)].

PubMed

Rossmann, P; Matousovic, K; Bucek, J

1975-01-01

In four renal biopsies of two patients with chronic glomerulonephritis (GN), the so-called dense deposit nephropathy (NDD) was diagnosed by means of light, electron, and immunofluorescence microscopy. In routine paraffin sections the picture approached that of the membrano-proliferative GN. In semithin sections (toluidine blue, periodic acid-Ag-methenamine) and especially in the ultrastructure there appeared extensive confluent deposits of a very dense substance, infiltrating the lamina densa of glomerular capillaries, basal membranes of both Bowman's capsules and tubules, and arteriolar walls. In this localization, a non-diffuse "psdudolinear" deposition of beta1c was detected, whereas antisera to main Ig-fractions and fibrin(ogen) were not fixed. In a biopsy performed six years later, a concentration of dense depositis towards the mesangial area and a partial regeneration of basal membranes were observed. In a part of dense deposits there appeared vacuolization, primarily in tubular and arteriolar basal membranes. In glomeruli, focal IgM deposits were apparent at an advanced stage. NDD apparently is a sequel of a particular metabolic (immune?) process, afflicting solely the renal membranous system and distinctly dns known at present. The noncharacteristic clinical presentation resembles chronic. GN, is very protracted, lengthy, and relatively benigh, with a chance of functional and possible even morphological remission.

Atmospheric mercury in the Southern Hemisphere tropics: seasonal and diurnal variations and influence of inter-hemispheric transport

NASA Astrophysics Data System (ADS)

Howard, Dean; Nelson, Peter F.; Edwards, Grant C.; Morrison, Anthony L.; Fisher, Jenny A.; Ward, Jason; Harnwell, James; van der Schoot, Marcel; Atkinson, Brad; Chambers, Scott D.; Griffiths, Alan D.; Werczynski, Sylvester; Williams, Alastair G.

2017-09-01

Mercury is a toxic element of serious concern for human and environmental health. Understanding its natural cycling in the environment is an important goal towards assessing its impacts and the effectiveness of mitigation strategies. Due to the unique chemical and physical properties of mercury, the atmosphere is the dominant transport pathway for this heavy metal, with the consequence that regions far removed from sources can be impacted. However, there exists a dearth of long-term monitoring of atmospheric mercury, particularly in the tropics and Southern Hemisphere. This paper presents the first 2 years of gaseous elemental mercury (GEM) measurements taken at the Australian Tropical Atmospheric Research Station (ATARS) in northern Australia, as part of the Global Mercury Observation System (GMOS). Annual mean GEM concentrations determined at ATARS (0.95 ± 0.12 ng m-3) are consistent with recent observations at other sites in the Southern Hemisphere. Comparison with GEM data from other Australian monitoring sites suggests a concentration gradient that decreases with increasing latitude. Seasonal analysis shows that GEM concentrations at ATARS are significantly lower in the distinct wet monsoon season than in the dry season. This result provides insight into alterations of natural mercury cycling processes as a result of changes in atmospheric humidity, oceanic/terrestrial fetch, and convective mixing, and invites future investigation using wet mercury deposition measurements. Due to its location relative to the atmospheric equator, ATARS intermittently samples air originating from the Northern Hemisphere, allowing an opportunity to gain greater understanding of inter-hemispheric transport of mercury and other atmospheric species. Diurnal cycles of GEM at ATARS show distinct nocturnal depletion events that are attributed to dry deposition under stable boundary layer conditions. These cycles provide strong further evidence supportive of a multi-hop model of GEM cycling, characterised by multiple surface depositions and re-emissions, in addition to long-range transport through the atmosphere.

Volcanogenic Massive Sulfide Deposits of the World - Database and Grade and Tonnage Models

USGS Publications Warehouse

Mosier, Dan L.; Berger, Vladimir I.; Singer, Donald A.

2009-01-01

Grade and tonnage models are useful in quantitative mineral-resource assessments. The models and database presented in this report are an update of earlier publications about volcanogenic massive sulfide (VMS) deposits. These VMS deposits include what were formerly classified as kuroko, Cyprus, and Besshi deposits. The update was necessary because of new information about some deposits, changes in information in some deposits, such as grades, tonnages, or ages, revised locations of some deposits, and reclassification of subtypes. In this report we have added new VMS deposits and removed a few incorrectly classified deposits. This global compilation of VMS deposits contains 1,090 deposits; however, it was not our intent to include every known deposit in the world. The data was recently used for mineral-deposit density models (Mosier and others, 2007; Singer, 2008). In this paper, 867 deposits were used to construct revised grade and tonnage models. Our new models are based on a reclassification of deposits based on host lithologies: Felsic, Bimodal-Mafic, and Mafic volcanogenic massive sulfide deposits. Mineral-deposit models are important in exploration planning and quantitative resource assessments for two reasons: (1) grades and tonnages among deposit types vary significantly, and (2) deposits of different types occur in distinct geologic settings that can be identified from geologic maps. Mineral-deposit models combine the diverse geoscience information on geology, mineral occurrences, geophysics, and geochemistry used in resource assessments and mineral exploration. Globally based deposit models allow recognition of important features and demonstrate how common different features are. Well-designed deposit models allow geologists to deduce possible mineral-deposit types in a given geologic environment and economists to determine the possible economic viability of these resources. Thus, mineral-deposit models play a central role in presenting geoscience information in a useful form to policy makers. The foundation of mineral-deposit models is information about known deposits. The purpose of this publication is to present the latest geologic information and newly developed grade and tonnage models for VMS deposits in digital form. This publication contains computer files with information on VMS deposits from around the world. It also presents new grade and tonnage models for three subtypes of VMS deposits and a text file allowing locations of all deposits to be plotted in geographic information system (GIS) programs. The data are presented in FileMaker Pro and text files to make the information available to a wider audience. The value of this information and any derived analyses depends critically on the consistent manner of data gathering. For this reason, we first discuss the rules used in this compilation. Next, we provide new grade and tonnage models and analysis of the information in the file. Finally, the fields of the data file are explained. Appendix A gives the summary statistics for the new grade-tonnage models and Appendix B displays the country codes used in the database.

Sediment characteristics and configuration within the Otsego City Dam impoundment on the Kalamazoo River, Michigan, 2001-02

USGS Publications Warehouse

Rheaume, S.J.; Hubbell, D.L.; Rachol, C.M.; Simard, A.; Fuller, L.M.

2004-01-01

The removal of the Otsego City Dam on the Kalamazoo River at Otsego, Mich., is under consideration by the Michigan Department of Environmental Quality and the city of Otsego. The historical discharge of papermill waste containing polychlorinated biphenyls from sources upstream from the dam has led the U.S. Environmental Protection Agency to designate the Kalamazoo River from Morrow Dam near Comstock to its mouth near Saugatuck as a Federal Superfund site. The papermill waste is concentrated in organic sediment and kaolinite clay, with the sediment containing as much as 94 milligrams per kilogram polychlorinated biphenyls. This contaminated sediment could move if the dam is removed; therefore, it is necessary to estimate the characteristics and configuration of the sediment before removal plans begin. Data from augered sections and sediment cores show that the current Otsego City impoundment sediments were deposited in two distinctly different sedimentary environments: (1) lacustrine sediments consisting of organic-rich silt and clay, fine to medium sand, and some gravel deposited in a repetitive, cyclic fashion related to former stream velocities when the Otsego City impoundment water levels were 2-4 feet higher (1880s-1960s), and from downstream movement of lacustrine sediments during the removal of the upstream Plainwell Dam superstructure in the 1980s; and (2) more recent (1980s-2002) coarse-grained alluvium deposited on top of the lacustrine sediments. The volume of instream sediment contained within the Otsego City impoundment is estimated to be about 457,270 cubic yards. This estimate is based on the composite thicknesses of the lacustrine deposits and overlying alluvium, which were determined to contain PCBs, and does not include bank or flood-plain deposits.

Facies associations, depositional environments and stratigraphic framework of the Early Miocene-Pleistocene successions of the Mukah-Balingian Area, Sarawak, Malaysia

NASA Astrophysics Data System (ADS)

Murtaza, Muhammad; Rahman, Abdul Hadi Abdul; Sum, Chow Weng; Konjing, Zainey

2018-02-01

Thirty-five stratigraphic section exposed along the Mukah-Selangau road in the Mukah-Balingian area have been studied. Sedimentological and palynological data have been integrated to gain a better insight into the depositional architecture of the area. Broadly, the Mukah-Balingian area is dominated by fluvial, floodplain and estuarine related coal-bearing deposits. The Balingian, Begrih and Liang formations have been described and interpreted in terms of seven facies association. These are: FA1 - Fluvial-dominated channel facies association; FA2 - Tide-influenced channel facies association; FA3 - Tide-dominated channel facies association; FA4 - Floodplain facies association; FA5 - Estuarine central basin-mud flats facies association; FA6 - Tidal flat facies association and FA7 - Coastal swamps and marshes facies association. The Balingian Formation is characterised by the transgressive phase in the base, followed by a regressive phase in the upper part. On the basis of the occurrence of Florscheutzia trilobata with Florscheutzia levipoli, the Early to Middle Miocene age has been assigned to the Balingian Formation. The distinct facies pattern and foraminifera species found from the samples taken from the Begrih outcrop imply deposition in the intertidal flats having pronounced fluvio-tidal interactions along the paleo-margin. Foraminiferal data combined with the pronounced occurrence of Stenochlaena laurifolia suggest at least the Late Miocene age for the Begrih Formation. The internal stratigraphic architecture of the Liang Formation is a function of a combination of sea level, stable tectonic and autogenic control. Based on stratigraphic position, the Middle Pliocene to Pleistocene age for the Liang Formation is probable. The Balingian, Begrih and Liang formations display deposits of multiple regressive-transgressive cycles while the sediments were derived from the uplifted Penian high and Rajang group.

Phyllosilicate and Hydrated Sulfate Deposits in Meridiani

NASA Technical Reports Server (NTRS)

Wiseman, S. M.; Avidson, R. E.; Murchie, S.; Poulet, F.; Andrews-Hanna, J. C.; Morris, R. V.; Seelos, F. P.

2008-01-01

Several phyllosilicate and hydrated sulfate deposits in Meridiani have been mapped in detail with high resolution MRO CRISM [1] data. Previous studies have documented extensive exposures of outcrop in Meridiani (fig 1), or etched terrain (ET), that has been interpreted to be sedimentary in origin [e.g., 2,3]. These deposits have been mapped at a regional scale with OMEGA data and show enhanced hydration (1.9 m absorption) in several areas [4]. However, hydrated sulfate detections were restricted to valley exposures in northern Meridiani ET [5]. New high resolution CRISM images show that hydrated sulfates are present in several spatially isolated exposures throughout the ET (fig 1). The hydrated sulfate deposits in the valley are vertically heterogeneous with layers of mono and polyhydrated sulfates and are morphologically distinct from other areas of the ET. We are currently mapping the detailed spatial distribution of sulfates and searching for distinct geochemical horizons that may be traced back to differential ground water recharge and/or evaporative loss rates. The high resolution CRISM data has allowed us to map out several phyllosilicate deposits within the fluvially dissected Noachian cratered terrain (DCT) to the south and west of the hematite-bearing plains (Ph) and ET (fig 1). In Miyamoto crater, phyllosilicates are located within 30km of the edge of Ph, which is presumably underlain by acid sulfate deposits similar to those explored by Opportunity. The deposits within this crater may record the transition from fluvial conditions which produced and/or preserved phyllosilicates deposits to a progressively acid sulfate dominated groundwater system in which large accumulations of sulfate-rich evaporites were deposited .

The impact of transport processes on rare earth element patterns in marine authigenic and biogenic phosphates

NASA Astrophysics Data System (ADS)

Auer, Gerald; Reuter, Markus; Hauzenberger, Christoph A.; Piller, Werner E.

2017-04-01

Rare earth elements (REEs) are commonly used proxies to reconstruct water chemistry and oxygen saturation during the formation of authigenic and biogenic phosphates in marine environments. In the modern ocean REEs exhibit a distinct pattern with enrichment of heavy REEs and strong depletion in cerium (Ce). The wide range of REE enrichment patterns found in ancient marine phosphates lead to the proposition that water chemistry has been very different in the Earth's past. However, both early and late diagenesis are known to affect REE signatures in phosphates altering primary marine signals. Herein we present a dataset of REE signatures in 38 grain specific LA-ICP-MS measurements of isolated phosphate and carbonate grains in three discrete rock samples. The phosphates mainly consist of authigenic phosphates and phosphatized microfossils that formed in a microbially mediated micro-milieu. In addition, isolated biogenic and reworked phosphatic grains are also present. The phosphates are emplaced in bioclastic grain- to packstones deposited on a carbonate ramp setting in the central Mediterranean Sea during the middle Miocene Monterey event. The results reveal markedly different REE patterns (normalized to the Post Archean Australian Shale standard) in terms of total enrichment and pattern shape. Analyses of REE diagenesis proxies show that diagenetic alteration affected the samples only to a minor degree. Grain shape and REE patterns together indicate that authigenic, biogenic and reworked phosphates have distinct REE patterns irrespective of the sample. Our study shows that while REE patterns in phosphates do reflect water chemistry during authigenesis, they are often already heavily altered during reworking, a process, which can occur in geologically negligible timespans. REE patterns are therefore more likely to reflect complex enrichment processes after their formation. Similarities in the REE patterns of reworked and biogenic phosphate further suggest that the frequently observed hat-shaped pattern in biogenic phosphates can result from increased middle REE (Neodymium to Holmium) scavenging during taphonomic processes prior to final deposition. Cluster analysis coupled with sedimentological and previously published geochemical data (bulk carbon isotope and X-ray fluorescence spectrometry) allowed the characterization of REE patterns of phosphates in terms of their formation conditions and depositional history, such as the distinction of phosphates formed in situ from reworked and transported phosphate grains.

75 FR 24384 - Reserve Requirements of Depository Institutions Policy on Payment System Risk

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-05

... balances. Institutions eligible to receive earnings on their balances in accounts at Federal Reserve Banks... general level of short-term interest rates. Term deposits are separate and distinct from balances... maintained in an excess balance account. Term deposits do not satisfy an institution's required reserve...

Stratigraphy of Aeolis Dorsa, Mars: Stratigraphic context of the great river deposits

NASA Astrophysics Data System (ADS)

Kite, Edwin S.; Howard, Alan D.; Lucas, Antoine S.; Armstrong, John C.; Aharonson, Oded; Lamb, Michael P.

2015-06-01

Unraveling the stratigraphic record is the key to understanding ancient climate and past climate changes on Mars (Grotzinger, J. et al. [2011]. Astrobiology 11, 77-87). Stratigraphic records of river deposits hold particular promise because rain or snowmelt must exceed infiltration plus evaporation to allow sediment transport by rivers. Therefore, river deposits when placed in stratigraphic order could constrain the number, magnitudes, and durations of the wettest (and presumably most habitable) climates in Mars history. We use crosscutting relationships to establish the stratigraphic context of river and alluvial-fan deposits in the Aeolis Dorsa sedimentary basin, 10°E of Gale crater. At Aeolis Dorsa, wind erosion has exhumed a stratigraphic section of sedimentary rocks consisting of at least four unconformity-bounded rock packages, recording three or more distinct episodes of surface runoff. Early deposits (>700 m thick) are embayed by river deposits (>400 m thick), which are in turn unconformably draped by fan-shaped deposits (<100 m thick) which we interpret as alluvial fans. Yardang-forming layered deposits (>900 m thick) unconformably drape all previous deposits. River deposits embay a dissected landscape formed of sedimentary rock. The river deposits are eroding out of at least two distinguishable units. There is evidence for pulses of erosion during the interval of river deposition. The total interval spanned by river deposits is >(1 × 106-2 × 107) yr, and this is extended if we include alluvial-fan deposits. Alluvial-fan deposits unconformably postdate thrust faults which crosscut the river deposits. This relationship suggests a relatively dry interval of >4 × 107 yr after the river deposits formed and before the fan-shaped deposits formed, based on probability arguments. Yardang-forming layered deposits unconformably postdate all of the earlier deposits. They contain rhythmite and their induration suggests a damp or wet (near-) surface environment. The time gap between the end of river deposition and the onset of yardang-forming layered deposits is constrained to >1 × 108 yr by the high density of impact craters embedded at the unconformity. The time gap between the end of alluvial-fan deposition and the onset of yardang-forming layered deposits was at least long enough for wind-induced saltation abrasion to erode 20-30 m into the alluvial-fan deposits. We correlate the yardang-forming layered deposits to the upper layers of Gale crater's mound (Mt. Sharp/Aeolis Mons), and the fan-shaped deposits to Peace Vallis fan in Gale crater. Alternations between periods of low mean obliquity and periods of high mean obliquity may have modulated erosion-deposition cycling in Aeolis. This is consistent with the results from an ensemble of simulations of Solar System orbital evolution and the resulting history of the obliquity of Mars. 57 of our 61 simulations produce one or more intervals of continuously low mean Mars obliquity that are long enough to match our Aeolis Dorsa unconformity data.

Pin stripe lamination: A distinctive feature of modern and ancient eolian sediments

USGS Publications Warehouse

Fryberger, S.G.; Schenk, C.J.

1988-01-01

Pin stripe laminations are a distinctive feature of modern and ancient eolian sediments. In sets of eolian ripple (or translatent) strata they represent deposition of silt and very fine sand in the troughs of the advancing wind ripples. In sets of avalanche strata they probably result from the downward settling of fine sand and silt within the moving avalanche to the interface of moving and unmoving sands. Wind tunnel experiments suggest that pin stripe laminations can also form in grainfall deposits. The textural segregation associated with deposition of the fine layers in most cases leads to early cementation along and near the finest sand and silt comprising the pin stripe lamination. The pin stripe effect seen in outcrops is usually due to resistance to weathering along such cemented zones. The cementation of the pin stripe laminations can occur early in the history of diagenesis and thus may provide clues to the post-depositional history of the rock. Pin stripe laminations in many instances represent the sequestering of the small population of ultrafine sediment present in most eolian depositional systems. They may prove useful in the recognition of ancient eolian sediments. ?? 1988.

Chapter C: Hydrothermal Enrichment of Gallium in Zones of Advanced Argillic Alteration-Examples from the Paradise Peak and McDermitt Ore Deposits, Nevada

USGS Publications Warehouse

Rytuba, James J.; John, David A.; Foster, Andrea; Ludington, Steven D.; Kotlyar, Boris

2003-01-01

Gallium is produced as a byproduct from bauxite and zinc sulfide ores and rarely from primary Ga ores. High Ga contents (>60 ppm) can occur in zones of advanced argillic alteration consisting of alunite+kaolinite+quartz associated with quartz-alunite (high sulfidation Au-Ag) deposits. In a magmatic-hydrothermal environment, the zones of advanced argillic alteration associated with quartz-alunite (high sulfidation) Au-Ag deposits have the highest Ga contents (max 120 ppm). In these Au deposits, Ga is enriched in the zone of alunite+kaolinite alteration and depleted in the zone of quartz-rich alteration within acid-leached rocks. Peripheral zones of argillic alteration have Ga contents and Al/Ga ratios similar to those in unaltered volcanic rocks. The zones of advanced argillic alteration that formed in a steam-heated environment in association with hot-spring-type Hg-Au deposits are not Ga enriched, and residual silicified zones have very low Ga contents. The McDermitt Hg and Paradise Peak Au-Hg deposits, Nev., have zones of advanced argillic alteration that are Ga enriched. At the Paradise Peak Au-Hg deposits, Ga is enriched in the zone of alunite+jarosite alteration that formed in a magmatic-hydrothermal environment. Ga is depleted in the zone of opal+alunite alteration formed in a steam-heated environment, in residual silicified zones formed in a magmatic-hydrothermal environment, and in zones of supergene jarosite alteration. At the McDermitt Hg deposit, Ga is enriched in the zone of alunite+kaolinite alteration below the zone of adularia-quartz alteration that coincides with the Hg ore body. The spatial relation of Ga enrichment to alunite-kaolinite alteration suggests that formation in a magmatic-hydrothermal environment. X-ray-absorption spectra of Ga-enriched samples from the McDermitt Hg deposit are similar to that of gallium sulfate and support the association of Ga enrichment with alunite alteration.

Granulometry and mineralogy of some northeastern Florida placers: a consequence of heavy mineral concentration in nearshore bars

NASA Astrophysics Data System (ADS)

Elsner, Harald

1992-03-01

Heavy mineral placer deposits of Pleistocene age in northeastern Florida were examined sedimentologically. Neither general setting, nor granulometric or mineralogic results are in agreement with a concentration of the heavy minerals in a beach, eolian or fluvial environment. Granulometric moment parameters of the ore sands seem to be distinctive. They include moderate sorting, high positive skewness, high kurtosis and a distinctive fine tail. Similarities of grain size curves of the placer sands with nearshore-offshore sands exist. Mineralogically the samples are more variable but always impoverished in epidote. This scarcity of epidote is atypical for eolian sediments in the study area, and the lack of garnet and the fineness of ore sands are uncommon for beach placers of northeast Florida. Underlain by dune ridges, which acted as obstacles on the shallow sea floor during the Penholoway transgression (1.3 ± 0.1 Ma B.P.), heavy minerals in the Boulogne and Green Cove Springs main ore body must have been concentrated in bars by the interplay of longshore and transverse bottom currents. Lighter heavy minerals were deposited in smaller nearshore bars closer to the former coast (Green Cove Springs small ore body) or in dunes of barrier islands (Green Cove Springs western ore body). As is true today, layers of noteworthy concentrations of economic minerals in the swash zone of Florida beaches were formed only rarely during storms, contrary to the coasts of Australia or India, where higher energetic conditions prevail. The proposed model of concentration of heavy minerals in certain outer nearshore bars has long been assumed but never been proven.

Zeolite-clay mineral zonation of volcaniclastic sediments within the McDermitt caldera complex of Nevada and Oregon

USGS Publications Warehouse

Glanzman, Richard K.; Rytuba, James J.

1979-01-01

Volcaniclastic sediments deposited in the moat of the collapsed McDermitt caldera complex have been altered chiefly to zeolites and potassium feldspar. The original rhyolitic and peralkaline ash-flow tuffs are included in conglomerates at the caldera rims and grade into a lacustrine series near the center of the collapse. The tuffs show a lateral zeolitic alteration from almost fresh glass to clinoptilolite, clinoptilolite-mordenite, and erionite; to analcime-potassium feldspar; and finally to potassium feldspar. Vertical zonation is in approximately the same order. Clay minerals in associated mudstones, on the other hand, show little lateral variation but a distinct vertical zonation, having a basal dioctahedral smectite, a medial trioctahedral smectite, and an upper dioctahedral smectite. The medial trioctahedral smectite is enriched in lithium (as much as 6,800 ppm Li). Hydrothermal alteration of the volcaniclastic sediments, forming both mercury and uranium deposits, caused a distinct zeolite and clay-mineral zonation within the general lateral zonation. The center of alteration is generally potassium feldspar, commonly associated with alunite. Potassium feldspar grades laterally and vertically to either clinoptilolite or clinoptilolite-mordenite, generally associated with gypsum. This zone then grades vertically and laterally into fresh glass. The clay minerals are a dioctahedral smectite, a mixed-layer clay mineral, and a 7-A clay mineral. The mixed-layer and 7-A clay minerals are associated with the potassium feldspar-alunite zone of alteration, and the dioctahedral smectite is associated with clinoptilolite. This mineralogical zonation may be an exploration guide for mercury and uranium mineralization in the caldera complex environment.

Fossils of hydrothermal vent worms from Cretaceous sulfide ores of the Samail ophiolite, Oman

USGS Publications Warehouse

Haymon, R.M.; Koski, R.A.; Sinclair, C.

1984-01-01

Fossil worm tubes of Cretaceous age preserved in the Bayda massive sulfide deposit of the Samail ophiolite, Oman, are apparently the first documented examples of fossils embedded in massive sulfide deposits from the geologic record. The geologic setting of the Bayda deposit and the distinctive mineralogic and textural features of the fossiliferous samples suggest that the Bayda sulfide deposit and fossil fauna are remnants of a Cretaceous sea-floor hydrothermal vent similar to modern hot springs on the East Pacific Rise and the Juan de Fuca Ridge.

The Influences of Geologic Depositional Environments on Sand Boil Development, Tara Wildlife Lodge Area in Mississippi

DTIC Science & Technology

2016-03-01

ER D C/ G SL T R- 16 -7 The Influences of Geologic Depositional Environments on Sand Boil Development, Tara Wildlife Lodge Area in...client/default. ERDC/GSL TR-16-7 March 2016 The Influences of Geologic Depositional Environments on Sand Boil Development, Tara Wildlife Lodge...Army Corps of Engineers Washington, DC 20314-1000 ERDC/GSL TR-16-7 ii Abstract A comprehensive study of the subsurface geology in the Tara Wildlife

Distribution and region-specific sources of Dechlorane Plus in marine sediments from the coastal East China Sea.

PubMed

Wang, Guoguang; Peng, Jialin; Hao, Ting; Liu, Yao; Zhang, Dahai; Li, Xianguo

2016-12-15

Dechlorane Plus (DP) is a highly chlorinated flame retardant and found to be ubiquitously present in the environment. We reported here the first record of DP in sediments from the coastal East China Sea (ECS). DP was detected in most of the surface sediments, and the concentrations ranged from 14.8 to 198pg/g dry weight (dw) with a mean value of 64.4pg/g dw. Overall, DP levels exhibited a seaward decreasing trend from the inshore toward outer sea. The fractional abundance of anti-DP (f anti ) showed regional discrepancies, attributing to different environmental behaviors of DP isomers. Depth profiles of DP in a sediment core from estuarine environment showed distinct fluctuation, and the core in open sea had stable deposition environment with two peak values of DP in ~1978 and 2000. The f anti exhibited downward decreasing trend prior to mid-1950s, indicating a preferential degradation of anti-DP and/or a greater adsorption capacity of syn-DP after its burial. Lignin and lipid biomarkers (∑C 27 +C 29 +C 31 n-alkanes) of terrestrial organic matters were introduced to identify region-specific sources of DP, and the results showed that DP in the northern inner shelf, southern inner shelf of 29 °N and mud area southwest of Cheju Island was mainly come from Yangtze River (YR) input, surface runoffs after discharge of local sources close to the Taizhou-Wenzhou Region and the atmospheric deposition from the North China and East Asia, respectively. The coastal ECS was an important reservoir of DP in the world, with mass inventory of approximately 310.7kg in the surface sediments (0-5cm). Copyright © 2016 Elsevier B.V. All rights reserved.

Quantification of diagenesis in Cenozoic sharks: Elemental and mineralogical changes

NASA Astrophysics Data System (ADS)

Labs-Hochstein, Joann; MacFadden, Bruce J.

2006-10-01

Diagenesis of bone during fossilization is pervasive, however, the extent of this process varies with depositional environment. This study quantifies diagenesis of shark vertebral centra through analysis of a suite of physical and chemical characters including crystallinty index (CI), carbonate content, and elemental concentrations. Although shark skeletons are initially cartilaginous, the soft cartilage of the vertebral centra is replaced with carbonate hydroxyapatite during growth. Nine vertebral centra are analyzed from lamnoid (Lamnoidea) sharks ranging in age from the cretaceous to recent using Fourier transform infrared spectroscopy (FT-IR) and inductively coupled plasma mass spectrometry (ICPMS). The variables CI, carbonate content, rare earth element (REE) concentrations, Ca/P, Ba/Ca, Sr/Ba, (La/Yb) N, (La/Y) N, (La/Yb) N vs. (La/Sm) N, La/Yb, and Ce anomalies elucidate the diagenetic and depositional environments of the seven fossil vertebral centra. The two extant centra demonstrate the initial, unaltered end-member conditions for these variables. Two fossil vertebral centra ( Carcharodon megalodon and Isurus hastalis) demonstrate a strong terrestrial influence during diagenesis (distinctive flattening of shale-normalized REE patterns) that masked the seawater signal. Three centra ( Carcharodon auriculatus, Carcharodon angustidens, and Creotxyrhina mantelli) have indications of some terrestrial influx evident by some flattening of the REE patterns relative to seawater. The terrestrial influence in these five shark centra ( C. megalodon, I. hastalis, C. auriculatus, C. angustidens and C. mantelli) are interpreted to represent a primarily nearshore habitat for these species. In contrast, the two Otodus obliquus centra have REE patterns that represent the original seawater signal and have no indications of terrigenous input. These results indicate that fossil shark vertebral centra have the potential to understand diagenesis and reconstruct paleooceanographic environments.

Volcanic Coatings on Picritic Apollo 17 Glasses; Submicrometer-Deposits of Fe-CR-Metal

NASA Technical Reports Server (NTRS)

McKay, David S.; Wentworth, S. J.; Thomas-Keprta, K. L.; Ross, K.; Clementt, S. J.

2010-01-01

The purposes of our ongoing investigations of Apollo 15 green and Apollo 17 orange and black volcanic glasses are threefold: first, to increase our understanding of the volcanic origin of the glasses; second, to determine the nature of the coating materials deposited on the glasses during their cooling in the volcanic environment; and, third, to help determine the nature of the gases involved in the volcanic fire-fountaining that occurred at approximately 3.5 Ga on the moon. We are continuing studies of coatings on volcanic glasses using analytical techniques not available when these glasses were originally studied; these include high-resolution FE-TEM and X-ray mapping, along with other highly detailed methods including TEM electron diffraction analysis. Initial studies of Apollo 15 green volcanic glasses using the techniques described above revealed for the first time the presence of areas containing distinct layering of volcanic surface deposits. S was associated with some of the inner layer of metallic Fe but was absent from the outer layer. Zn was associated with S in some places in the inner layer. An example of a typical spherule used for this study is shown in Fig. 1. It is a black (quench-crystallized) bead from near the bottom of the 74001/2 double drive tube; black beads such as this one are essentially identical in composition to the orange (uncrystallized) beads of the 74001/2 core.

Stratigraphy, sedimentology, and volume of sediments behind a dam relic on the Muskegon River, Big Rapids, Michigan

USGS Publications Warehouse

Westjohn, David B.

1997-01-01

The proposed removal of the remnants of a hydroelectric dam in the Muskegon River at Big Rapids, Michigan, will potentially affect flow of the river at the city's water intake system. Fifteen boreholes were augered in bottom sediments in the river just upstream from the dam relic, and streambottom profiles were made using ground-penetrating radar. Data from boreholes show that sediments captured by the dam foundation were deposited in two distinctly different sedimentary environments. Sediments that overlie the pre-dam channel surface consist of lacustrine clay, wood chips, silt, and sand. These lacustrine sediments are interbedded in a cyclical fashion, and they were deposited under low flow to stagnant water conditions during 1916-66, when a 17-foot-tall hydroelectric dam was in place. Demolition of the upper 13 feet of this dam in 1966 resulted in erosion of most of the lacustrine sediments, and subsequent deposition of coarser alluvium in the impoundment behind the remaining dam foundation. Lacustrine sediments are present in the active part of the stream channel and extend from the dam foundation to about 1,300 feet upstream. The composite thickness of lacustrine sediments and overlying coarser alluvium was determined from sediment cores collected from the boreholes. The volume of these sediments is estimated to be about 19,000 cubic yards.

Proterozoic low-Ti iron-oxide deposits in New York and New Jersey: relation to Fe-oxide (Cu-U-Au-rare earth element) deposits and tectonic implications

USGS Publications Warehouse

Foose, M.P.; McLelland, J.M.

1995-01-01

Low-Ti iron-oxide deposits in exposed Grenville-age rocks of New York and New Jersey belong to a distinct class of iron-oxide (Cu-U-Au-rare earth element [REE]) deposits that includes similar iron deposits in southeastern Missouri and the Kiruna district of Sweden, the giant Olympic Dam U-Cu-Au-Ag deposit (Australia), and the Bayan Obo REE-Nb deposit (China). Most of the New York-New Jersey deposits exhibit features consistent with a hydrothermal origin and define a regionally significant metallogenic event that provides important clues to the evolution of this part of the Grenville orogen. In the Adirondacks, the tectonic setting of these deposits is consistent with postorogenic uplift and extensive crustal melting at 1070-1050 Ma that was accompanied by late tectonic to posttectonic deposition of iron. -Authors

Effects of the low Earth orbit space environment on the surface chemistry of Kapton polyimide film: An XPS study

NASA Technical Reports Server (NTRS)

Lee, Myung; Rooney, William; Whiteside, James

1992-01-01

Kapton H (DuPont Trademark) polyimide specimens exposed to the low earth (LEO) space environment suffered significant weathering with surface erosions of approximately 8.0 microns. Despite these effects, no significant changes in bulk chemistry were observed. X-ray photoelectron spectroscopy (XPS) was used to determine local changes induced from approximately 25 percent in 1980 vintage ground control specimens to nearly 53 percent in space exposed specimens. The greatest increase was observed for the divalent oxygen moieties, although a slight increase in carbonyl oxygen was also measured. Furthermore, the chemical shifts of all XPS peaks of space-exposed Kapton are shifted to higher energy. This is consistent with a higher oxidation state of the space exposed surface. Finally, space exposed specimens had distinct silicon peaks (2p 100 eV and 2s 149 eV) in their XPS spectra in agreement with widespread reports of silicon contamination throughout the LDEF satellite. These results are discussed in terms of surface reactivity of the polyimide exposed to the LEO environment and the chemical nature of contaminants deposited on flight surfaces due to satellite outgassing.

Reservoir performance of Late Eocene incised valley fills, Cusiana Field, Llanos Foothills, Eastern Colombia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pulham, A.; Edward, W.; App, J.

1996-12-31

The Cusiana Field is located in the Llanos Foothills of Eastern Colombia. The principal reservoir is the late Eocene Mirador Formation which comprises >50% of reserves. Currently the Mirador reservoir is providing nearly all of the 150,00bopd of production from the Cusiana Field. The Mirador reservoir comprises a stack of incised valley deposits. The fills of the valleys are dominated by quartz arenite sandstones. The average porosity of the valley sandstones is 8% which reflects abundant quartz cement ({approximately}14%) and significant compaction during deep burial ({approximately}20,000feet). Single valleys are up to 70 feet thick and exhibit a distinctive bipartite fillmore » that reflects changing energy conditions during filling. Bases of valleys have the coarsest grain size and have sedimentological and trace fossil evidence for deposition in highly stressed, brackish water environments. The upper parts of the valleys are typically finer grained and were deposited in more saline settings. Despite the low porosity of the Mirador valleys, drill stem tests and production log data show that they have phenomenal performance characteristics. Rates of {ge}10,000bopd are achieved from single valleys. Bases of the valley fills are the key contributors to flow. Integration of detailed core and pore system analysis with the reservoir performance data shows that the permeability fabric of the Mirador can be explained by original depositional architecture and simple loss of primary porosity. Comparison of Cusiana with other quartz-rich sandstones from around the world suggests that it`s low porosity/high performance is predictable.« less

Distinctive features of kinetics of plasma at high specific energy deposition

NASA Astrophysics Data System (ADS)

Lepikhin, Nikita; Popov, Nikolay; Starikovskaia, Svetlana

2016-09-01

A nanosecond capillary discharge in pure nitrogen at moderate pressures is used as an experimental tool for plasma kinetics studies at conditions of high specific deposited energy up to 1 eV/molecule. Experimental observations based on electrical (back current shunts, capacitive probe) and spectroscopic measurements (quenching rates; translational, rotational and vibrational temperature measurements) demonstrate that high specific deposited energy, at electric fields of 200-300 Td, can significantly change gas kinetics in the discharge and in the afterglow. The numerical calculations in 1D axially symmetric geometry using experimental data as input parameters show that changes in the plasma kinetics are caused by extremely high excitation degree: up to 10% of molecular nitrogen is electronically excited at present conditions. Distinctive features of kinetics of plasma at high specific energy deposition as well as details of the experimental technique and numerical calculations will be present. The work was partially supported by French National Agency, ANR (PLASMAFLAME Project, 2011 BS09 025 01), AOARD AFOSR, FA2386-13-1-4064 grant (Program Officer Prof. Chiping Li), LabEx Plas@Par and Linked International Laboratory LIA KaPPA (France-Russia).

Sediment characteristics and configuration within three dam impoundments on the Kalamazoo River, Michigan, 2000

USGS Publications Warehouse

Rheaume, S.J.; Rachol, C.M.; Hubbell, D.L.; Simard, Andreanne

2002-01-01

The removal of the remnants of three hydroelectric dams on the Kalamazoo River near Plainwell, Otsego, and Allegan, Michigan, has been proposed. The benefits of this removal include returning the Kalamazoo River to its pre-dam flow, increasing recreational use and safety on the river, and improving aquatic habitat. The U.S. Environmental Protection Agency has designated this reach of the Kalamazoo River as a Federal Superfund site because of the historical discharge of papermill waste containing polychlorinated biphenyls. Much of this waste material remains concentrated in organic sediment and kaolinite clay deposited upstream from the three dam foundations. Sediment containing up to 150 milligrams per kilogram polychlorinated biphenyls could move if dam foundations are removed; therefore, it is necessary to estimate the characteristic and configuration of the sediment before work begins. Data collected from augered sections and sediment cores show that impoundment sediments were deposited in two distinctly different sedimentary environments. Interbedded lacustrine sediments that overlie the pre-dam channel surface consist of organic-rich silt and clay, fine to medium sand, and some gravel. These materials were deposited in a repetitive, cyclic fashion related to former stream velocities when the impoundment water levels were 5-10 feet higher. Lowering of these water levels and demolition of the superstructures of these dams resulted in erosion of much of these instream lacustrine sediments and subsequent deposition of coarse-grained alluvium in the impounded channel behind the remaining dam foundations. The composite thicknesses of the lacustrine deposits and overlying alluvium was determined from sediment cores collected from each impoundment. The volume of instream sediment contained in each impoundment is estimated to be about 77,600 cubic yards at the Plainwell impoundment; 268,900 cubic yards at the Otsego impoundment; and 1,192,600 cubic yards at the Trowbridge impoundment. Estimates do not include bank or flood-plain deposits.

Seminoe 3, a tidally influenced lowstand wedge and its relationships with subjacent highstand and overlying transgressive deposits, Haystack Mountains Formation, Cretaceous Western Interior, Wyoming (USA)

NASA Astrophysics Data System (ADS)

Mellere, Donatella

1996-06-01

The Campanian Haystack Mountains Formation (Wyoming, USA) consists of a series of deltaic/estuarine and shoreface sandstone tongues stacked in basinward-stepping units separated by shale intervals. Regional analysis indicates that the tongues have a distinctive two-tiered architecture: (a) a lower sandbody with bioturbated and hummocky strata of wave-dominated shoreface origin; and (b) an erosively based upper unit with bioturbated to tabular cross-bedded sandstones. This study focuses on a single tongue, Seminoe 3, which crops out in a 40 km long continuous dip-oriented exposure. In its landward reaches (westwards) the tongue consists of a thin unit of offshore-transitional to lower shoreface deposits. In the central part of the exposure it becomes thicker and consists of a cross-bedded wedge which truncates the shoreface deposits and pinches out by downlap eastwards onto a thick, westward migrating, shoreface lithosome (spit), probably developed on the margin of a wave-dominated delta. Detailed correlation and mapping of bounding surfaces indicate that the shoreface and spit lithosomes were deposited in a forced regressive mode during falling relative sea-level. The overlying cross-bedded lithosome, is a lowstand wedge which prograded over an incised topography created during the early stage of sea-level lowstand. A large embayment is suggested to have developed during the highstand/forced regressive phase, with shoreline and spit deposits prograding from opposing sides. Significant erosion and truncation occurred during the lowstand phase, as well as a basinward shift of facies onto the shelf and the pre-existing spit deposits. In the early stage of transgression the embayment was drowned, and a tide-dominated, estuarine environment was established. The resulting cross-bedded wedge displays an aggrading to prograding stacking pattern of parasequences with the uppermost portion exhibiting a retrogradational pattern, as a consequence of the reworking operated by the transgression.

Facies architecture and sequence-stratigraphic features of the Tumbiana Formation: A depositional setting of late Archaean stromatolites in the Pilbara Craton, northwestern Australia

NASA Astrophysics Data System (ADS)

Sakurai, R.; Ueno, Y.; Kitajima, K.; Ito, M.; Maruyama, S.

2001-12-01

The Tumbiana Formation (ca. 2700 Ma) is a succession developed in response to late Archaean crustal extension in the Pilbara Craton, northwestern Australia. The formation is characterized by intercalations of stromatolite carbonates and provides a perspective of evolution of photosynthetic organisms that are interpreted to have been responsible for oxygenation of atmosphere. Here we investigated a depositional setting of the stromatolite limestone for better understanding of an environment that may have controlled early development of oxygenic photosynthesis. We studied lithofacies and sequence-stratigraphic features of the Tumbiana Formation in the Redmont area based upon three-dimensional analyses of onshore outcrops. The Tumbiana Formation, as much as 170 m thick, unconformably overlies the early Archaean basement rocks and is unconformably overlain by the Maddina Formation that consists of mafic tuffaceous sediments and basalt. The lower part of the Tumbiana Formation is characterized by planar- and trough-cross stratified conglomerates that are interpreted to be an alluvial-fan deposit shed from the northern hinterlands and developed mainly in local depressions of the basement rocks during an early transgressive stage. The base of the middle part is defined by a transgressive erosional surface overlain by conglomerates and/or breccia that pass upward to mafic tuffaceous mudstones and sandstones intercalated with accretionary lapilli, breccia, and basalt. Mudstones are commonly laminated and sandstones contain current- and wave ripple-lamination, parallel lamination, hummocky cross-stratification, and trough cross-stratification. In general, the middle part exhibits an overall fining- and coarsening-upward pattern and is interpreted to indicate transgressive and regressive shelf-to-coastal lithofacies successions. In particular, the uppermost horizon of the middle part is characterized by sandstone beds with herringbone structures and desiccation cracks and is interpreted to indicate an intertidal environment developed during a late highstand stage. The middle part, in general, thickens to the northern proximal area and eventually flattens out topographic irregularity of the basement rocks. The upper part is characterized by stromatolite carbonates, associated with minor wave- and current-rippled sandstones and desiccation cracks, and does not exhibit distinct lateral variation in thickness. The base of the upper part is also characterized by a transgressive lag deposit and the ensuing transgression over intertidal deposits of the middle part is interpreted to have developed an accommodation space for the vertical stacking of stromatolites with different external shapes from columnar and small domal types to a large domal type that may have responded to the increase in paleowater depth possibly from intertidal to subtidal environments. In conclusion, stromatolites in the upper Tumbiana Formation in the Redmont area are interpreted to have developed in coastal and shallow marine environments in response to a rise in relative sea level rather than in ephemeral saline lakes as proposed by previous studies from different locations.

Exhumed subglacial landscape in Uruguay: Erosional landforms, depositional environments, and paleo-ice flow in the context of the late Paleozoic Gondwanan glaciation

NASA Astrophysics Data System (ADS)

Assine, Mario Luis; de Santa Ana, Héctor; Veroslavsky, Gerardo; Vesely, Fernando F.

2018-07-01

A well-exposed glacial surface sculpted on Precambrian crystalline basement rocks occurs below the glacial succession of the San Gregorio Formation on the eastern border of the Chaco-Parana Basin in Uruguay and was formed in the context of the late Paleozoic Gondwana Ice Age. On the glacial surface are asymmetric parallel streamlined bedrock landforms interpreted as whalebacks. The downglacier (lee-side) faces of the whalebacks have gentle slopes dipping NNW with striated and sometimes polished surfaces on crystalline rocks. These landforms are covered by 10-100-cm-thick layers of tillites and shear-laminated siltstones, suggesting glacial abrasion produced mainly by subglacial till sliding. The subglacial facies are ice-molded, and exhibit meso-scale glacial lineations such as ridges and grooves up to 30 m long and 30 cm deep. The subglacial association is directly overlain by proglacial fine-grained facies (rhythmites) with dropstones indicating a subaqueous depositional environment following ice-margin retreat. The fine-grained facies are erosively cut by a succession of sandstones with wave-generated stratification resting on a basal conglomerate. Intraformational striated surfaces, NNE-oriented, were found on four distinct bedding planes within the sandstone package and interpreted as ice keel scour marks produced by floating ice. The San Gregorio deposits are partially confined in a wide and shallow subglacial trough and the stratigraphic succession is interpreted as the record of a glacial advance-retreat cycle comparable to deglacial sequences from other late Paleozoic localities. The paleo-ice flow to the NNW indicated by subglacial lineations is parallel to that verified in the southernmost Paraná Basin located north of the study area, suggesting a paleogeographic scenario in which glaciers advanced northward into a glaciomarine environment. The proposed palaeogeography does not confirm the previous hypothesis of an ice center on the Sul-Riograndense Shield but, instead, it corroborates a south-derived Uruguayan Ice Lobe advancing to the north, probably with provenance far afield in terranes of the present-day southern African.

Classification of Martian deltas

NASA Technical Reports Server (NTRS)

Dehon, R. A.

1993-01-01

Water-borne sediments in streams are deposited, upon eventual cessation of flow, either as deltas or as alluvial fans or plains. Deltas and alluvial fans share a common characteristic; both may be described as deposition Al plains at the mouth of a river or stream. A delta is formed where a stream or river deposits its sedimentary load into a standing body of water such as an ocean or lake. An alluvial fan is produced where a stream loses capacity by a greatly decreased gradient. A delta has subaerial and subaqueous components, but an alluvial fan is entirely subaerial. In terrestrial conditions, deltas and alluvial fans are reasonably distinct landforms. The juxtaposition of concomitant features composition and internal structure are sufficiently explicit as to avoid any confusion regarding their proper identification on Mars, the recognition of deltas and their distinction from alluvial fans is made difficult by low resolution imaging. Further, although it may be demonstrated that standing bodies of water existed on the surface of Mars, many of these bodies may have existed for extremely short periods of time (a few days to months); hence, distinctive shoreline features were not developed. Thus, in an attempt to derive a Martian classification of deltas, the inclusion of wholly subaerial deposits may be unavoidable. A simple, broad, morphological classification of Martian deltas, primarily on planimetric shape, includes digitate deltas, fan-shaped deltas, and re-entrant deltas. A fourth, somewhat problematical class includes featureless plains at the end of many valley systems.

The history of soil erosion: Interpreting historical sources, buried soils and colluvial sediments as archives of past soil erosion and human-environment interactions in the Longue Durée

NASA Astrophysics Data System (ADS)

Dotterweich, Markus

2015-04-01

Soil erosion threatens the environment and the sustainability of agricultural practices since the earliest societies started modifying their natural environment in the Neolithic. Almost all farming-based cultures in the world, from large civilizations to peasant groups on little islands, have suffered from soil erosion by water. The amounts of soil erosion varied largely through time and space, and extreme events have left a wide variety of imprints on the landscape over millennia. Eroded hillslopes and gullies, deposited sediments in sinks like lakes, footslopes, valleys, floodplains, and river deltas are geomorphic legacies that have been linked to changes in land use and climate by many studies during the last decades. However, a standardized analysis and interpretation of these geomorphic legacies is problematic because of the variety of methodological approaches and the nonlinearity between soil erosion, climate, and land use. Cascading effects, land use structures, soil management, soil conservation strategies, and long-term system changes have produced different signals over time. Historical records are crucial and an invaluable source to provide alternative proxies about soil erosion in the past. Direct observations of individual soil erosion events may restrict the deposition of a distinct sediment package to a certain time span. They also expand the range of alternative interpretations, particularly with respect to the long-term effects of soil erosion to ecosystem services and socioeconomic processes. However, historical records also need critical analyses regarding their origin, intention, and quality. They were often created in the context of personal interests or political issues rather than being based on scientific facts; and it is often unclear if they represent certain events, narratives, or vague assumptions. This presentation will present and discuss examples of geomorphic evidences and historical records of past soil erosion for the deciphering of human-environment interactions in the Longue Durée.

Chemical-Vapor-Deposited Diamond Film

NASA Technical Reports Server (NTRS)

Miyoshi, Kazuhisa

1999-01-01

This chapter describes the nature of clean and contaminated diamond surfaces, Chemical-vapor-deposited (CVD) diamond film deposition technology, analytical techniques and the results of research on CVD diamond films, and the general properties of CVD diamond films. Further, it describes the friction and wear properties of CVD diamond films in the atmosphere, in a controlled nitrogen environment, and in an ultra-high-vacuum environment.

Comparative geology and geochemistry of sedimentary-rock-hosted (Carlin Type) gold deposits in the People's Republic of China and in Nevada, USA

USGS Publications Warehouse

Li, Zhiping; Peters, Stephen G.

1998-01-01

Sedimentary-rock-hosted (Carlin-type) gold deposits have been considered economically significant and geologically distinct since the early 1960's. This report consists of a nine-part text and an interactive database. This small database is to help Western companies get more information about these gold deposits in China, and to help geologists who are interested in world Carlin-type deposits conduct research on them. Because of their economic significance and geological distinctiveness, these deposits have caught the interest of economic geologists all over the world since the early 1960's. Similar deposits have been discovered in China, Australia, Dominican Republic, Spain, and Russia besides Nevada. Perhaps most significant are the 165 Carlin-type gold deposits that were found in southwest China during the past 15 years. Of these, at least 19 deposits have proven to be of substantial tonnage, making China the second leading country to exploit such deposits. With the increasing interest in Chinese Carlin-type gold deposits, some western companies and geologists desire to get more information about these Chinese deposits. This seems to have been very difficult because the literature was in Chinese. It is estimated that several hundred scientific publications (including papers, books, and technical reports) have been published. This database of Chinese Carlin-type Gold deposits is built on the documentation published during the most recent 10 years and includes six subjects, which consist of 165 records and 30 fields. A new Proterozoic-age sedimentary-rock-hosted gold deposit in northeastern P.R. China also is described. Note that for the old version 1.1 on the CD-ROM, the latitude and longitude locations of the mineral occurrences have been estimated from sketch maps and journal articles and are not intended for digital analysis. One of the improvements in this version 1.2 is the accuracy of geographic data. Version 1.3 updates to the database and includes maps and photos of deposits, deposit information and a geochemical model. See the version history for details.

SPATIALLY RESOLVED SPECTROSCOPY OF EUROPA: THE DISTINCT SPECTRUM OF LARGE-SCALE CHAOS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fischer, P. D.; Brown, M. E.; Hand, K. P., E-mail: pfischer@caltech.edu

2015-11-15

We present a comprehensive analysis of spatially resolved moderate spectral resolution near-infrared spectra obtained with the adaptive optics system at the Keck Observatory. We identify three compositionally distinct end member regions: the trailing hemisphere bullseye, the leading hemisphere upper latitudes, and a third component associated with leading hemisphere chaos units. We interpret the composition of the three end member regions to be dominated by irradiation products, water ice, and evaporite deposits or salt brines, respectively. The third component is associated with geological features and distinct from the geography of irradiation, suggesting an endogenous identity. Identifying the endogenous composition is ofmore » particular interest for revealing the subsurface composition. However, its spectrum is not consistent with linear mixtures of the salt minerals previously considered relevant to Europa. The spectrum of this component is distinguished by distorted hydration features rather than distinct spectral features, indicating hydrated minerals but making unique identification difficult. In particular, it lacks features common to hydrated sulfate minerals, challenging the traditional view of an endogenous salty component dominated by Mg-sulfates. Chloride evaporite deposits are one possible alternative.« less

Carbonatites of the World, Explored Deposits of Nb and REE - Database and Grade and Tonnage Models

USGS Publications Warehouse

Berger, Vladimir I.; Singer, Donald A.; Orris, Greta J.

2009-01-01

This report is based on published tonnage and grade data on 58 Nb- and rare-earth-element (REE)-bearing carbonatite deposits that are mostly well explored and are partially mined or contain resources of these elements. The deposits represent only a part of the known 527 carbonatites around the world, but they are characterized by reliable quantitative data on ore tonnages and grades of niobium and REE. Grade and tonnage models are an important component of mineral resource assessments. Carbonatites present one of the main natural sources of niobium and rare-earth elements, the economic importance of which grows consistently. A purpose of this report is to update earlier publications. New information about known deposits, as well as data on new deposits published during the last decade, are incorporated in the present paper. The compiled database (appendix 1; linked to right) contains 60 explored Nb- and REE-bearing carbonatite deposits - resources of 55 of these deposits are taken from publications. In the present updated grade-tonnage model we have added 24 deposits comparing with the previous model of Singer (1998). Resources of most deposits are residuum ores in the upper part of carbonatite bodies. Mineral-deposit models are important in exploration planning and quantitative resource assessments for two reasons: (1) grades and tonnages among deposit types vary significantly, and (2) deposits of different types are present in distinct geologic settings that can be identified from geologic maps. Mineral-deposit models combine the diverse geoscience information on geology, mineral occurrences, geophysics, and geochemistry used in resource assessments and mineral exploration. Globally based deposit models allow recognition of important features and demonstrate how common different features are. Well-designed deposit models allow geologists to deduce possible mineral-deposit types in a given geologic environment, and the grade and tonnage models allow economists to estimate the possible economic viability of these resources. Thus, mineral-deposit models play a central role in presenting geoscience information in a useful form to policy makers. The foundation of mineral-deposit models is information about known deposits. This publication presents the latest geologic information and newly developed grade and tonnage models for Nb- and REE-carbonatite deposits in digital form. The publication contains computer files with information on deposits from around the world. It also contains a text file allowing locations of all deposits to be plotted in geographic information system (GIS) programs. The data are presented in FileMaker Pro as well as in .xls and text files to make the information available to a broadly based audience. The value of this information and any derived analyses depends critically on the consistent manner of data gathering. For this reason, we first discuss the rules used in this compilation. Next, the fields of the database are explained. Finally, we provide new grade and tonnage models and analysis of the information in the file.

Natural abundance N stable isotopes in plants and soils as an indicator of N deposition hotspots in urban environments

NASA Astrophysics Data System (ADS)

Trammell, T. L.

2017-12-01

The natural abundance of stable isotopes in plants and soils has been utilized to understand ecological phenomenon. Foliar δ15N is an integrator of soil δ15N, atmospheric N sources, and fractionation processes that occur during plant N uptake, plant N assimilation, and mycorrhizal associations. The amount of reactive N in the environment has greatly increased due to human activities, and urban ecosystems experience excess N deposition that can have cascading effects on plants and soils. Foliar δ15N has been shown to increase with increasing N deposition and nitrification rates suggesting increased foliar δ15N occurs with greater N inputs as a result of accelerated soil N cycling. Thus, foliar δ15N can be an indication of soil N availability for plant uptake and soil N cycling rates, since high N availability results in increased soil N cycling and subsequent loss of 14N. Limited research has utilized foliar and soil δ15N in urban forests to assess the importance of plant uptake of atmospheric N deposition and to gain insight about ecosystem processes. Previous investigations found foliar δ15N of mature trees in urban forests is not only related to elevated pollutant-derived N deposition, but also to soil N availability and soil N cycling rates. Similarly, enriched foliar δ15N of urban saplings was attributed to soil characteristics that indicated higher nitrification, thus, greater nitrate leaching and low N retention in the urban soils. These studies demonstrate the need for measuring the δ15N of various plant and soil N sources while simultaneously measuring soil N processes (e.g., net nitrification rates) in order to use natural abundance δ15N of plants and soils to assess N sources and cycling in urban forests. A conceptual framework that illustrates biogenic and anthropogenic controls on nitrogen isotope composition in urban plants and soils will be presented along with foliar and soil δ15N from urban forests across several cities as a proof of concept. Foliar and soil 15N can be extremely useful when N sources are isotopically distinct, patterns are detectable, or multiple tools are used simultaneously to understand N cycling. N cycles tightly in most ecosystems, thus δ15N in plants and soils can provide information about N source and availability to ecosystems.

Pleistocene environmental dynamics recorded in the loess of the middle and lower Danube basin

NASA Astrophysics Data System (ADS)

Fitzsimmons, Kathryn E.; Marković, Slobodan B.; Hambach, Ulrich

2012-05-01

The substantial loess deposits of the middle and lower Danube basin in southeastern Europe represent one of the thickest and most comprehensive terrestrial palaeoenvironmental records on the continent, yet are also the least well understood. Environmental conditions over the last million years have resulted in relatively continuous deposits uninterrupted by glaciation and tundra conditions, which nevertheless reflect oscillations between relatively warm-humid (“interglacial”) and cold-dry (“glacial”) intervals. This relative environmental stability may have proven important for hominins migrating into and through the region. The loess stratigraphy comprises distinct loess-paleosol sequences, reflecting glacial-interglacial phases which can be quantified for intensity using environmental magnetism and geochemistry. These phases are emphasised by variations in vegetation and malacofauna which respond to climatic change. The loess deposits demonstrate broadly similar sedimentological characteristics across the basin. Danubian loess deposits initiated in response to the tectonic formation of the Pannonian basin, retreat of the large palaeolakes, and increased sediment supply from the Danube. The period from ˜1 Ma-500 ka (MIS 27-13) was characterised by alternating loess deposition and pedogenesis during glacial and interglacial periods respectively, in response to relatively humid, forested conditions. This period represents the opening of the Danube corridor and provides the backdrop for initial hominin arrival into Europe. After ˜500 ka, and particularly after MIS 9, loess accumulation rates increased in response to relatively more steppic, arid, environments. MIS 9 and 13-15 were the most humid phases of the last ˜600 ky. The MIS 5 interglacial period was the warmest, and relatively most humid, period preceding the Holocene, and was followed by substantially increased loess accumulation during MIS 4, which may be linked to North Atlantic circulation. The complexity of the MIS 3 interstadial paleosol suggests that conditions were not uniformly warm and wet during this time. MIS 3 corresponds with the first arrival of anatomically modern humans to Europe. The last glacial maximum and Younger Dryas of MIS 2 were characterised by substantially increased loess accumulation indicating cold steppe environments most likely influenced by the North Atlantic, although conditions were sufficiently mild that the region acted as a refugium for thermophilic biota, as may also have been the case for most of the Pleistocene glacial cycles. The Holocene soil represents relatively wamer and more humid conditions corresponding to the current interglacial.

Subsurface structure around Omi basin using borehole database

NASA Astrophysics Data System (ADS)

Kitada, N.; Ito, H.; Takemura, K.; Mitamura, M.

2015-12-01

Kansai Geo-informatics Network (KG-NET) is organized as a new system of management of GI-base in 2005. This organization collects the geotechnical and geological information of borehole data more than 60,000 data. GI-base is the database system of the KG-NET and platform to use these borehole data. Kansai Geo-informatics Research Committee (KG-R) is tried to explain the geotechnical properties and geological environment using borehole database in Kansai area. In 2014, KG-R established the 'Shin-Kansai Jiban Omi plain', and explain the subsurface geology and characteristics of geotechnical properties. In this study we introduce this result and consider the sedimental environment and characteristics in this area. Omi Basin is located in the central part of Shiga Prefecture which includes the largest lake in Japan called Lake Biwa. About 15,000 borehole data are corrected to consider the subsurface properties. The outline of topographical and geological characteristics of the basin is divided into west side and east side. The west side area is typical reverse fault called Biwako-Seigan fault zone along the lakefront. From Biwako-Seigan fault, the Omi basin is tilting down from east to west. Otherwise, the east areas distribute lowland and hilly area comparatively. The sedimentary facies are also complicate and difficult to be generally evaluated. So the discussion has been focused about mainly the eastern and western part of Lake Biwa. The widely dispersed volcanic ash named Aira-Tn (AT) deposited before 26,000-29,000 years ago (Machida and Arai, 2003), is sometimes interbedded the humic layers in the low level ground area. However, because most of the sediments are comprised by thick sand and gravels whose deposit age could not be investigated, it is difficult to widely identify the boundary of strata. Three types of basement rocks are distributed mainly (granite, sediment rock, rhyolite), and characteristics of deposit are difference of each backland basement rock. Therefore, we considered the characteristics of area deposit as each riverine system. Otherwise, lakeside area are distributes many humic layers and sandy beach ridge. The results of each distinctive trend are useful to estimate of seismic properties and zonation.

Overview of Initial Results from CRISM

NASA Astrophysics Data System (ADS)

Seelos, F.; Murchie, S.; Mustard, J.; Pelkey, S.; Roach, L.; Elhmann, B.; Arvidson, R.; Wiseman, S.; Milliken, R.; CRISM Team

2007-05-01

The Mars Reconnaissance Orbiter (MRO) reached 100 days of primary science phase operations on February 15th, 2007. Over this time period, the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) has acquired high spatial resolution hyperspectral observations and contextual multispectral survey data of type localities that record water-rock interaction through much of the geologic history of Mars. CRISM's primary science objectives are to characterize the mineralogical record of past aqueous environments and to monitor the contemporary spatial and seasonal distributions of volatiles in the surface-atmosphere system. These objectives are accomplished through an observation strategy that includes targeted data acquisition, atmospheric and seasonal monitoring, and global mapping. Targeted observations are acquired by gimbaling the instrument along-track to reduce apparent ground motion, resulting in a spatial resolution of 15-20 m/pixel in 544 wavelengths from 362 to 3920 nm. As a part of each targeted observation 10 additional spatially binned images are acquired at different atmospheric path lengths, creating an emission phase function (EPF) that allows surface-atmosphere separation in the analysis of the observed radiance. The atmospheric and seasonal monitoring campaigns consist of global grids of EPF measurements at regular Ls intervals. In CRISM's global mapping campaign, data are acquired in a push broom observing mode at a reduced spatial and spectral resolution of 200m/pxl and 72 selected spectral channels. Initial data analysis reveals evidence for environmental variability throughout Martian history. Noachian deposits exhibit diverse phyllosilicate mineralogy in a greater number of geologic units than previously recognized. Distinct mineralogic signatures are sometimes separated only by hundreds of meters, indicating variability in alteration environment or parent rock composition. Hesperian layered deposits exhibit strong vertical heterogeneity with different abundances and types of sulfate minerals, suggesting local environmental changes on short geologic timescales. The Amazonian north polar layered deposits exhibit complex vertical layering in the abundance and/or grain size of water ice. The underlying basal unit shows little evidence for ice except in restricted locations where the morphology is consistent with subsequent modification of the deposits by fluid flow. Multispectral mapping is nearly complete at the high northern latitudes and shows evidence for significant hydrated mineral content in portions of the basal unit.

Paleoclimatic insights from mapping the global distribution of non-glacial cryogenic landforms in sub-humid montane environments.

NASA Astrophysics Data System (ADS)

Slee, Adrian; Shulmeister, James

2015-04-01

Much of the 'periglacial' literature is based on landforms and observations from either high mountains or continental environments dominated by strong winter cooling and/or permafrost conditions. Cryogenic conditions occur in many other settings and some of the most widespread are montane landscapes in mid- to low latitudes. In Australia observations of 'periglacial' landforms have traditionally been limited to higher elevation regions of the Australian Alps and central Tasmania. However, the distribution of relict cryogenic landforms is much wider and extends well into sub-tropical latitudes along the eastern highlands of Australia. Here we map the distribution of relict block deposits (block streams and block fields) of known cryogenic origin so as to delineate the limits of 'periglacial' climatic conditions during cold phases in the Late Quaternary. The mapping is based on image analyses supported by extensive and intensive ground truthing. Three distinct regimes are recognised - a high elevation winter wet regime (Mt Kosciuszko style); a temperate maritime westerly regime (Tasmania style) and, unexpectedly, an east coast (sub-tropical) regime (New England style). We utilise bio-climatic modelling to derive modern climate parameters from the distribution of the block deposits so as to map regions affected by cryogenic conditions in late Quaternary cold periods. We assumed that relative changes in mean cooling and precipitation would be shared by other mid-latitude climate locales worldwide and predicted the likely distribution of block deposits in these areas. A literature review confirms the presence of 'periglacial' style block deposits in the predicted regions, including part of the Iberian Peninsula, the Atlas and Drakensburg Mountains of Africa, the Mediterranean island of Sardinia, the higher volcanoes of Mexico and parts of China, all of which have mean annual precipitation similar to the New England area. However, we also note that many of these areas have winter wet (Mediterranean) climates and when seasonality of precipitation is included, winter dry New England becomes an anomaly. We conclude that in addition to significant cooling, winter moisture balance was more positive, in northern New South Wales during cooler climate periods.

Seismic stratigraphic characteristics of upper Louisiana continental slope: an area east of Green Canyon

USGS Publications Warehouse

Bouma, Arnold H.; Feeley, Mary H.; Kindinger, Jack G.; Stelting, Charles E.; Hilde, Thomas W.C.

1981-01-01

A high-resolution seismic reflection survey was conducted in a small area of the upper Louisiana Continental Slope known as Green Canyon Area. This area includes tracts 427, 428, 471, 472, 515, and 516, that will be offered for sale in March 1982 as part of Lease Sale 67.The sea floor of this region is, slightly hummocky and is underlain by salt diapirs that are mantled by early Tertiary shale. Most of the shale is overlain by younger Tertiary and Quaternary deposits, although locally some of the shale protrudes the sea floor. Because of proximity to older Mississippi River sources, the sediments are thick. The sediment cover shows an abundance of geologic phenomena such as horsts, grabens, growth faults, normal faults, and consolidation faults, zones with distinct and indistinct parallel reflections, semi-transparent zones, distorted zones, and angular unconformities.The major feature of this region is a N-S linear zone of uplifted and intruded sedimentary deposits formed due to diapiric intrusion.Small scale graben development over the crest of the structure can be attributed to extension and collapse. Large scale undulations of reflections well off the flanks of the uplifted structure suggest sediment creep and slumping. Dipping of parallel reflections show block faulting and tilting.Air gun (5 and 40 cubic inch) records reveal at least five major sequences that show masked onlap and slumping in their lower parts grading into more distinct parallel reflections in their upper parts. Such sequences can be related to local uplift and sea level changes. Minisparker records of this area show similar sequences but on a smaller scale. The distinct parallel reflections often onlap the diapir flanks. The highly reflective parts of these sequences may represent turbidite-type deposition, possibly at times of lower sea level. The acoustically more transparent parts of each sequence may represent deposits containing primarily hemipelagic and pelagic sediment.A complex ridge system is present along the west side of the area and distinct parallel reflections onlap onto this structure primarily from the east. Much of this deposition may be ascribed to sedimentation within a submarine canyon whose position is controlled by this ridge.

Ion beam deposition of in situ superconducting Y-Ba-Cu-O films

NASA Astrophysics Data System (ADS)

Klein, J. D.; Yen, A.; Clauson, S. L.

1990-01-01

Oriented superconducting YBa2Cu3O7 thin films were deposited on yttria-stabilized zirconia substrates by ion beam sputtering of a nonstoichiometric oxide target. The films exhibited zero-resistance critical temperatures as high as 80.5 K without post-deposition anneals. Both the deposition rate and the c lattice parameter data displayed two distinct regimes of dependence on the beam power of the ion source. Low-power sputtering yielded films with large c dimensions and low Tc's. Higher power sputtering produced a continuous decrease in the c lattice parameter and an increase in critical temperatures.

Trace-fossil and storm-deposit relationships of San Carlos formation, west Texas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Metz, C.L.; Bednarski, S.P.

1986-05-01

Two distinct assemblages of trace fossils are preserved in the storm deposits in delta-front facies of the Upper Cretaceous San Carlos Formation, west Texas. The assemblages represent two widely differing responses to storm deposition and sediment-trace-fossil relationships, indicating that other environmental parameters, probably water depth and oxygen levels, influenced trace-fossil distribution within the San Carlos delta front. Evidence of the storm-deposited nature of the sandstones includes a scoured basal contact, planar to hummocky cross-stratification, and a upper contact that is either ripple marked or is gradational with overlying shales.

Microscopic physical biomarkers in carbonate hot springs: implications in the search for life on Mars

NASA Technical Reports Server (NTRS)

Allen, C. C.; Albert, F. G.; Chafetz, H. S.; Combie, J.; Graham, C. R.; Kieft, T. L.; Kivett, S. J.; McKay, D. S.; Steele, A.; Taunton, A. E.;

Gas-deposit-alloy corrosion interactions in simulated combustion environments

NASA Astrophysics Data System (ADS)

Luer, Kevin Raymond

High temperature corrosion in aggressive coal combustion environments involves simultaneous corrosion reactions between combustion gases, ash deposits, and alloys. This research investigated the behavior of a ferritic steel (SA387-Gr11) and three weld claddings (309L SS, Alloy 72, and Alloy 622) in five combustion environments beneath solid deposits at 500°C for up to 1000 hours. The synthetic gases consisted of N2-CO-CO-H2-H2O-H 2S-SO2 mixtures that simulated a range of fuel-rich or fuel-lean combustion environments with a constant sulfur content. The synthetic deposits contained FeS2, FeS, Fe3O4 and/or carbon. Reaction kinetics was studied in individual gas-metal, gas deposit, and deposit-alloy systems. A test method was developed to investigate simultaneous gas-deposit-metal corrosion reactions. The results showed reaction kinetics varied widely, depending on the gas-alloy system and followed linear, parabolic, and logarithmic rate laws. Under reducing conditions, the alloys exhibited a range of corrosion mechanisms including carburization-sulfidation, sulfidation, and sulfidation-oxidation. Most alloys were not resistant to the highly reducing gases but offered moderate resistance to mixed oxidation-sulfidation by demonstrating parabolic or logarithmic behavior. Under oxidizing conditions, all of the alloys were resistant. Under oxidizing-sulfating conditions, alloys with high Fe or Cr contents sulfated whereas an alloy containing Mo and W was resistant. In the gas-deposit-metal tests, FeS2-bearing deposits were extremely corrosive to low alloy steel under both reducing and oxidizing conditions but they had little influence on the weld claddings. Accelerated corrosion was attributed to rapid decomposition or oxidation of FeS2 particles that generated sulfur-rich gases above the alloy surface. In contrast, FeS-type deposits had no influence under reducing conditions but they were aggressive to low alloy steel under oxidizing conditions. The extent of damage correlated with the initial sulfur content in the deposit. Fe3O4 in the deposit was beneficial because it acted as a sulfur getter or oxygen source. Carbon had a mixed effect. The reaction behavior was modeled using computational thermochemistry based on Gibbs free energy minimization. A calculation method was introduced to predict equilibrium corrosion microstructures and trace reaction paths in complex gas-deposit-metal environments. Kinetic factors were identified where equilibrium reaction products were not experimentally observed.

Depositional environments of the Cache, Lower Lake, and Kelseyville Formations, Lake County, California

USGS Publications Warehouse

Rymer, Michael J.; Roth, Barry; Bradbury, J. Platt; Forester, Richard M.

1988-01-01

We describe the depositional environments of the Cache, Lower Lake, and Kelseyville Formations in light of habitat preferences of recovered mollusks, ostracodes, and diatoms. Our reconstruction of paleoenvironments for these late Cenozoic deposits provides a framework for an understanding of basin evolution and deposition in the Clear Lake region. The Pliocene and Pleistocene Cache Formation was deposited primarily in stream and debris flow environments; fossils from fine-grained deposits indicate shallow, fresh-water environments with locally abundant aquatic vegetation. The fine-grained sediments (mudstone and siltstone) were probably deposited in ponds in abandoned channels or shallow basins behind natural levees. The abandoned channels and shallow basins were associated with the fluvial systems responsible for deposition of the bulk of the technically controlled Cache Formation. The Pleistocene Lower Lake Formation was deposited in a water mass large enough to contain a variety of local environments and current regimes. The recovered fossils imply a lake with water depths of 1 to 5 m. However, there is strong support from habitat preferences of the recovered fossils for inferring a wide range of water depths during deposition of the Lower Lake Formation; they indicate a progressively shallowing system and the culmination of a desiccating lacustrine system. The Pleistocene Kelseyville Formation represents primarily lacustrine deposition with only minor fluvial deposits around the margins of the basin. Local conglomerate beds and fossil tree stumps in growth position within the basin indicate occasional widespread fluvial incursions and depositional hiatuses. The Kelseyville strata represent a large water mass with a muddy and especially fluid substrate having permanent or sporadic periods of anoxia. Central-lake anoxia, whether permanent or at irregular intervals, is the simplest way to account for the low numbers of benthic organisms recovered from the Kelseyville Formation. Similar low-oxygen conditions for benthic life are represented throughout the sedimentary history of Clear Lake. Water depths for the Kelseyville Formation of 10 to 30 m and 12 m near the margins of the basin are inferred both before and after fluvial incursions. These water-depth fluctuations cannot be correlated with major climatic changes as indicated by pollen and fossil leaves and cones; they may be due to faulting in this technically active region.

Permian depositional history, Leach Mountains, northeastern Nevada

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martindale, S.G.

1993-04-01

The 4,000 m thick Permian sequence in the Leach Mountains consists of carbonate rock, chert, terrigenous clastic rock and phosphatic rock. These rocks, in ascending order, comprise the Third Fork Fm., Badger Gulch Fm., Trapper Creek Fm., Grandeur Fm., Meade Peak Phosphatic Shale Tongue of the Phosphoria Fm., Murdock Mountain Fm. and Gerster Limestone. This sequence disconformably overlain by Triassic strata. Initial Permian deposition, represented by the late Wolfcampian to early Leonardian Third Fork Fm., was on a slope, at a water depth of about 50 m. Subsequently, a shallowing trend occurred during the early Leonardian to late Leonardian withmore » deposition of the Badger Gulch, Trapper Creek and Grandeur Fms. The Trapper Creek and Grandeur Fms. were deposited on the shelf, in very shallow subtidal to supratidal environments. The shelf persisted through the remainder of the Permian. In the late leonardian, the Meade Peak Tongue was deposited in very shallow subtidal and intertidal environments. A supratidal environment was re-established in latest Leonardian( ) to early Guadalupian with deposition of the lower Murdock Mountain Fm. The upper Murdock Mountain Fm. was deposited in very shallow subtidal to supratidal environments. Later during the early Guadalupian, intertidal to shallow subtidal deposition of the Gerster Limestone occurred. Angular phosphatic pebbles that were derived from phosphatic strata at the top of the Gerster Limestone are contained in the Triassic basal conglomerate. These pebbles indicate that the last Permian event was probably emergence and erosion of the top of the Gerster Limestone.« less

The Impact of Iodide-Mediated Ozone Deposition and Halogen Chemistry on Surface Ozone Concentrations Across the Continental United States

EPA Science Inventory

The air quality of many large coastal areas in the United States is affected by the confluence of polluted urban and relatively clean marine airmasses, each with distinct atmospheric chemistry. In this context, the role of iodide-mediated ozone (O3) deposition over seawater and m...

The MIS 5 palaeoenvironmental record in the SE Mediterranean coast of the Iberian Peninsula (Río Antas, Almería, Spain)

NASA Astrophysics Data System (ADS)

Torres, T.; Ortiz, J. E.; Blázquez, A. M.; Ruiz Zapata, B.; Gil, M. J.; Martín, T.; Sánchez-Palencia, Y.

2015-08-01

Landwards of a MIS5 bar, a borehole core (SRA) was analyzed to establish the relationship between the lagoonal record and the raised beach deposits in the surroundings of the Antas river mouth and to reconstruct the Pleistocene palaeoenvironmental evolution of the southern Mediterranean coast of the Iberian Peninsula. 63 samples were recovered for amino acid racemization dating, 86 samples for sedimentological and paleontological determination, 37 samples for pollen identification and 54 for biomarker analysis. AAR revealed that the borehole record contains MIS11, MIS6 and MIS5 deposits, the latter extensively represented. During the end of MIS6 and MIS5, a sand barrier developed and created a shallow lagoon with alternating terrestrial inputs this process being common in other Mediterranean realms. Litho- and biofacies allowed the identification of distinct paleoenvironments through time, with the presence of a lagoonal environment alternating with alluvial fan progradation. Biomarkers indicated constant input from terrestrial plants, together with variable development of aquatic macrophytes. The palynological content allowed the reconstruction of the paleoclimatological conditions during MIS6 and 5, with evidence of seven scenarios characterized by alternating arid and relatively humid conditions.

New Constraints on Post-LGM WAIS Retreat from the Whales Deep Paleo-ice-stream Trough in Eastern Ross Sea

NASA Astrophysics Data System (ADS)

DeCesare, M.; Bart, P. J.; Rosenheim, B. E.

2016-02-01

New multibeam and seismic data acquired during NBP1502 show that a back-stepping cluster containing at least four grounding zone wedges (GZWs) define a bathymetric saddle on the middle shelf of the Whales Deep paleo-ice-stream trough in eastern Ross Sea. Our synthesis of geophysical data with jumbo piston/kasten cores show that we penetrated diamict, sub-ice shelf and open marine sediments associated with four temporally distinct grounding events. A high number of well-preserved benthic and planktonic foraminifera were found in sediments we interpret to have been deposited in sub-ice shelf and open marine environments. A low number of similarly well-preserved benthic foraminifera were recovered from the underlying ice proximal diamict that was deposited on the GZW foreset. We tentatively propose that the pristine foraminifera are in situ and that these specimens provide a unique opportunity to constrain the retreat of grounded and floating ice from the eastern Ross Sea outer continental shelf. Our ongoing synthesis of new radiocarbon dates, stable isotope (δ18O and δ13C) and element/calcium ratios (e.g., Mg/Ca, B/Ca) will be presented.

A new assemblage of stem pecoran ruminants from the Oligocene Chitarwata Formation, Bugti Hills, Baluchistan, Pakistan: Paleoenvironmental and paleobiogeographic implications

NASA Astrophysics Data System (ADS)

Métais, Grégoire; Mennecart, Bastien; Roohi, Ghazala

2017-04-01

A new assemblage of stem pecoran ruminants from the Oligocene Chitarwata Formation (lower Bugti Member), Bugti Hills (Pakistan), consists of three identified genera and another indeterminate ruminant. Although limited, the dental and postcranial material is sufficient to identify the genera Amphitragulus and Mosaicomeryx, two common forms known from middle to late Oligocene deposits of Europe, thus reinforcing the 'middle' Oligocene age of the lowermost Chitarwata Formation. Mosaicomeryx is reported for the first time from the Indian Subcontinent and this occurrence considerably expands its geographical distribution. A new genus and species, Paalitherium gurki, is erected on the basis of an unusual and unique association of characters on its lower molars. The unclear definition and occurrences of? Gelocus gajensis Pilgrim, 1912 are re-examined in the light of new data from the Bugti and Zinda Pir areas (Pakistan). The new ruminant fauna from Paali is clearly distinctive from the early Miocene assemblage known from Bugti. In accordance with other fossil evidence, the ruminant fauna described here suggests the existence of a tropical forested environment under monsoonal regime with soft food supplies during the time of deposition of the lowermost Chitarwata Formation.

Low-Volatility Model Demonstrates Humidity Affects Environmental Toxin Deposition on Plastics at a Molecular Level.

PubMed

Hankett, Jeanne M; Collin, William R; Yang, Pei; Chen, Zhan; Duhaime, Melissa

2016-02-02

Despite the ever-increasing prevalence of plastic debris and endocrine disrupting toxins in aquatic ecosystems, few studies describe their interactions in freshwater environments. We present a model system to investigate the deposition/desorption behaviors of low-volatility lake ecosystem toxins on microplastics in situ and in real time. Molecular interactions of gas-phase nonylphenols (NPs) with the surfaces of two common plastics, poly(styrene) and poly(ethylene terephthalate), were studied using quartz crystal microbalance and sum frequency generation vibrational spectroscopy. NP point sources were generated under two model environments: plastic on land and plastic on a freshwater surface. We found the headspace above calm water provides an excellent environment for NP deposition and demonstrate significant NP deposition on plastic within minutes at relevant concentrations. Further, NP deposits and orders differently on both plastics under humid versus dry environments. We attributed the unique deposition behaviors to surface energy changes from increased water content during the humid deposition. Lastly, nanograms of NP remained on microplastic surfaces hours after initial NP introduction and agitating conditions, illustrating feasibility for plastic-bound NPs to interact with biota and surrounding matter. Our model studies reveal important interactions between low-volatility environmental toxins and microplastics and hold potential to correlate the environmental fate of endocrine disrupting toxins in the Great Lakes with molecular behaviors.

40 CFR 1610.4 - Deposition Transcripts.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 32 2010-07-01 2010-07-01 false Deposition Transcripts. 1610.4 Section... INVESTIGATIONS § 1610.4 Deposition Transcripts. (a) Transcripts of depositions of witnesses compelled by subpoena... by the person conducting the deposition. (b) Such a witness, after completing the compelled testimony...

40 CFR 1610.4 - Deposition Transcripts.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 33 2011-07-01 2011-07-01 false Deposition Transcripts. 1610.4 Section... INVESTIGATIONS § 1610.4 Deposition Transcripts. (a) Transcripts of depositions of witnesses compelled by subpoena... by the person conducting the deposition. (b) Such a witness, after completing the compelled testimony...

43 CFR 3830.12 - What are the characteristics of a locatable mineral?

Code of Federal Regulations, 2012 CFR

2012-10-01

... materials are locatable if they are uncommon because they possess a distinct and special value. As provided in McClarty v. Secretary of the Interior, 408 F.2d 907 (9th Cir. 1969), we determine whether mineral materials have a distinct and special value by: (1) Comparing the mineral deposit in question with other...

43 CFR 3830.12 - What are the characteristics of a locatable mineral?

Code of Federal Regulations, 2013 CFR

2013-10-01

... materials are locatable if they are uncommon because they possess a distinct and special value. As provided in McClarty v. Secretary of the Interior, 408 F.2d 907 (9th Cir. 1969), we determine whether mineral materials have a distinct and special value by: (1) Comparing the mineral deposit in question with other...

43 CFR 3830.12 - What are the characteristics of a locatable mineral?

Code of Federal Regulations, 2014 CFR

2014-10-01

... materials are locatable if they are uncommon because they possess a distinct and special value. As provided in McClarty v. Secretary of the Interior, 408 F.2d 907 (9th Cir. 1969), we determine whether mineral materials have a distinct and special value by: (1) Comparing the mineral deposit in question with other...

Neoproterozoic cap-dolostone deposition in stratified glacial meltwater plume

NASA Astrophysics Data System (ADS)

Liu, Chao; Wang, Zhengrong; Raub, Timothy D.; Macdonald, Francis A.; Evans, David A. D.

2014-10-01

Neoproterozoic cap carbonates host distinctive geochemical and sedimentological features that reflect prevailing conditions in the aftermath of Snowball Earth. Interpretation of these features has remained contentious, with hypotheses hinging upon timescale and synchronicity of deposition, and whether or not geochemical signatures of cap carbonates represent those of a well-mixed ocean. Here we present new high-resolution Sr and Mg isotope results from basal Ediacaran cap dolostones in South Australia and Mongolia. Least-altered Sr and Mg isotope compositions of carbonates are identified through a novel incremental leaching technique that monitors the purity of a carbonate sample and the effects of diagenesis. These data can be explained by the formation of these cap dolostones involving two chemically distinct solutions, a glacial meltwater plume enriched in radiogenic Sr, and a saline ocean residue with relatively lower 87Sr/86Sr ratios. Model simulations suggest that these water bodies remained dynamically stratified during part of cap-dolostone deposition, most likely lasting for ∼8 thousand years. Our results can potentially reconcile previous conflicts between timescales estimated from physical mixing models and paleomagnetic constraints. Geochemical data from cap carbonates used to interpret the nature of Snowball Earth and its aftermath should be recast in terms of a chemically distinct meltwater plume.

Well-preserved low thermal inertia ejecta deposits surrounding young secondary impact craters on Mars

NASA Astrophysics Data System (ADS)

Hill, J. R.; Christensen, P. R.

2017-06-01

Following the most recent updates to the Mars Odyssey Thermal Emission Imaging System daytime and nighttime infrared global mosaics, a colorized global map was produced that combines the thermophysical information from the nighttime infrared global mosaic with the morphologic context of the daytime infrared global mosaic. During the validation of this map, large numbers of low thermal inertia ejecta deposits surrounding small young impact craters were observed. A near-global survey (60°N-60°S) identified 4024 of these low thermal inertia ejecta deposits, which were then categorized based on their apparent state of degradation. Mapping their locations revealed that they occur almost exclusively in regions with intermediate-to-high thermal inertias, with distinct clusters in northern Terra Sirenum, Solis Planum, and southwestern Daedalia Planum. High-Resolution Imaging Science Experiment images show that the thermophysically distinct facies of the deposits are well correlated with the estimated average ejecta grain sizes, which decrease with radial distance from the crater. Comparisons with recent primary impact craters and secondary impact craters surrounding Zunil Crater show that the low thermal inertia ejecta deposits very closely resemble the secondary craters, but not the primary craters. We conclude that the low thermal inertia ejecta deposits are secondary impact crater ejecta deposits, many of which originated from the rayed crater primary impact events, and are both well preserved and easily identifiable due to the absence of dust cover and aeolian modification that would otherwise reduce the thermal contrast between the ejecta facies and the surrounding terrain.

Clinothem Lobe Growth and Possible Ties to Downslope Processes in the Gulf of Papua

NASA Astrophysics Data System (ADS)

Wei, E. A. Y.; Driscoll, N. W.; Milliman, J. D.; Slingerland, R. L.

2014-12-01

The Gulf of Papua is fed by the large-floodplain Fly River and small mountainous rivers to the north, thus creating an ideal environment where end-member cases of river systems and their deltas (e.g. the large-floodplain Brazos River and the narrow-shelved Eel River) can be studied. Input from five rivers into the gulf has constructed a three-dimensional mid-shelf clinothem composed of three depositional lobes, with a central lobe downlapped by two younger lobes to the north and south. This geometry suggests that the three lobes are not syndepositional but rather that clinoform depocenters have shifted 60 km, thus bypassing adjacent accommodation. Newly examined CHIRP (Compressed High Intensity Radar Pulse) seismic lines and XRF analysis of piston cores from the 2004 NSF MARGINS program reveal distinct lobes offshore that exhibit increased complexity moving shoreward. Evidence of shoreward complexity and lobe interfingering cause us to question the originally proposed mechanism for depocenter shift involving circulation changes. An alternative hypothesis that stems from distinct lobe architecture farther offshore suggests that channelized downslope processes and nearshore storage may play important roles in lobe growth.

Biological Low-pH Mn(II) Oxidation in a Manganese Deposit Influenced by Metal-Rich Groundwater

PubMed Central

Bohu, Tsing; Akob, Denise M.; Abratis, Michael; Lazar, Cassandre S.

2016-01-01

ABSTRACT The mechanisms, key organisms, and geochemical significance of biological low-pH Mn(II) oxidation are largely unexplored. Here, we investigated the structure of indigenous Mn(II)-oxidizing microbial communities in a secondary subsurface Mn oxide deposit influenced by acidic (pH 4.8) metal-rich groundwater in a former uranium mining area. Microbial diversity was highest in the Mn deposit compared to the adjacent soil layers and included the majority of known Mn(II)-oxidizing bacteria (MOB) and two genera of known Mn(II)-oxidizing fungi (MOF). Electron X-ray microanalysis showed that romanechite [(Ba,H2O)2(Mn4+,Mn3+)5O10] was conspicuously enriched in the deposit. Canonical correspondence analysis revealed that certain fungal, bacterial, and archaeal groups were firmly associated with the autochthonous Mn oxides. Eight MOB within the Proteobacteria, Actinobacteria, and Bacteroidetes and one MOF strain belonging to Ascomycota were isolated at pH 5.5 or 7.2 from the acidic Mn deposit. Soil-groundwater microcosms demonstrated 2.5-fold-faster Mn(II) depletion in the Mn deposit than adjacent soil layers. No depletion was observed in the abiotic controls, suggesting that biological contribution is the main driver for Mn(II) oxidation at low pH. The composition and species specificity of the native low-pH Mn(II) oxidizers were highly adapted to in situ conditions, and these organisms may play a central role in the fundamental biogeochemical processes (e.g., metal natural attenuation) occurring in the acidic, oligotrophic, and metalliferous subsoil ecosystems. IMPORTANCE This study provides multiple lines of evidence to show that microbes are the main drivers of Mn(II) oxidation even at acidic pH, offering new insights into Mn biogeochemical cycling. A distinct, highly adapted microbial community inhabits acidic, oligotrophic Mn deposits and mediates biological Mn oxidation. These data highlight the importance of biological processes for Mn biogeochemical cycling and show the potential for new bioremediation strategies aimed at enhancing biological Mn oxidation in low-pH environments for contaminant mitigation. PMID:26969702

Stratigraphic distribution, taphonomy and paleoenvironments of Spinicaudata in the Triassic and Jurassic of the Paraná Basin

NASA Astrophysics Data System (ADS)

Jenisch, Alan Gregory; Lehn, Ilana; Gallego, Oscar Florencio; Monferran, Mateo Daniel; Horodyski, Rodrigo Scalise; Faccini, Ubiratan Ferrucio

2017-12-01

Due to the chitino-phosphatic nature of Spinicaudata conchostracan exoskeletons, their carapaces exhibit a low preservational potential compared to other bivalve groups. However, the recent studies point towards the increased tolerance of the carapace against the physical processes. Due to this peculiar characteristic, conchostracan carapace have been utilized as precise temporal markers in estimating stratigraphic and taphonomic parameters. The same characteristic also makes the spinicaudatans useful in evaluating the depositional processes and environments. The present work aims at providing a paleoenvironmental and stratigraphic analysis of conchostracans (Spinicaudata) from the Triassic-Jurassic of the Paraná Basin (Santa Maria and Caturrita formations) in terms of the sedimentary facies analysis, depositional system characterization, and analysis of the taphonomic signatures of the fossiliferous horizons within these formations. The results from the taphonomic study delineates the presence of 4 distinct fossil assemblages based on the causative mechanism and fundamental characteristics of the fossil concentrations: two taphonomic assemblages in the laminated mudstone beds deposited from the decanting fine-grained sediments in floodplains; the sandstone beds with plane parallel laminations and dune- and ripple-cross-stratifications deposited from the flooding-related overflow in the floodplains; and the association of laminated mudstone and massive sandstone beds deposited as the river mouth bars. The results show that the taphonomic signatures, e.g., closed valves, may indicate the various patterns of autochthony and allochthony. In the fine-grained floodplain assemblages, the high degree of preservation can be attributed to autochthony in the conchostracans, whereas the preservational condition of floodplain sandstone sheet and mouth bar assemblages point toward parautochthony and even allochthony. Therefore, the preservational quality of conchostracan exoskeletons is likely a function of parameters, e.g., the transport duration, the distance from life position, and the magnitude of events causing their final burial. Within the observed species, the recognition of Eustheria minuta in the stratigraphic level of the Passo das Tropas creek corroborates an age for these deposits between the late Middle Triassic and early Upper Triassic. The presence of a new form, likely related to the family Fushunograptidae in sediments from the Caturrita Formation, suggests a Jurassic age for these deposits.

Millennial-scale record of overwash deposits preserved within lagoon sediments from the Arabian Peninsula

NASA Astrophysics Data System (ADS)

Griffis, A. M.; Jessica, P.; Reinhardt, E. G.; Kosciuch, T. J.; Kovacs, S. E.; Hoffmann, G.

2017-12-01

Coastlines along the Arabian Sea are susceptible to tsunami-related inundation due to their proximity to the Makran Subduction Zone (MSZ). This subduction zone has seen decades of low intensity events, but has historically produced large tsunamigenic-earthquakes that have impacted the 100 million people living along the Arabian Sea. One major problem in assessing the seismic risk of the MSZ is that the historical record of events are spatially and temporally limited and rely heavily on eye witness accounts. This hinders our ability to forecast the potential magnitude and recurrence intervals of earthquakes and tsunamis that can be expected in the future. Sediments deposited by paleotsunamis are useful as they expand the decadal record of events to include millennial timescales that more accurately capture the full range of magnitudes and recurrence intervals. On November 28, 1945 a 8.1 Mw earthquake originating from the MSZ generated a tsunami inundating coastlines along the Arabian Sea with wave heights up to 13m. At Sur, a small village on the northeastern coastline of Oman, the tsunami deposited a laterally continuous shell-rich layer within a 12 km2 lagoon. This layer contained distinctive taphonomic assemblages of foraminifera and bivalves. Below the 1945 shelly deposit at Sur Lagoon, seven anomalous sand layers were found preserved within fine-grained lagoonal sediment. These layers of medium-coarse sands range in thickness from 5 to 35 cm and are separated by sandy-mud sediment. Grain size analysis shows that these anomalously coarse layers are followed by an abrupt return to lagoonal mud. The sand layers have features consistent with the 1945 tsunami deposit such as fining upward trends, sharp basal contact, and marine foraminifera (e.g., Amphistegina sp., planktics). In contrast, the surrounding lagoon deposits are generally massive, finer in grain size, and contain foraminiferal species typically found in shallow quiescent coastal environments (e.g., Ammonia tepida, miliolids). We have attributed these seven marine sand layers to tsunami overwash deposition. Preliminary radiocarbon dating of articulated bivalve shells establish a late Holocene age range for the tsunami sand layers with ongoing analyses further constraining timings leading to assessing relative magnitudes of past events.

Sunlight affects aggregation and deposition of graphene oxide in the aquatic environment.

EPA Science Inventory

In this study, we investigate the role of simulated sunlight on the physicochemical properties, aggregation, and deposition of graphene oxide (GO) in aquatic environments. Results show that light exposure under varied environmental conditions significantly impacts the physicochem...

A New Azhdarchid Pterosaur from the Late Cretaceous of the Transylvanian Basin, Romania: Implications for Azhdarchid Diversity and Distribution

PubMed Central

Vremir, Mátyás; Kellner, Alexander W. A.; Naish, Darren; Dyke, Gareth J.

2013-01-01

We describe a new taxon of medium-sized (wing span ca. 3 m) azhdarchid pterosaur from the Upper Cretaceous Transylvanian Basin (Sebeş Formation) of Romania. This specimen is the most complete European azhdarchid yet reported, comprising a partially articulated series of vertebrae and associated forelimb bones. The new taxon is most similar to the Central Asian Azhdarcho lancicollis Nessov but possesses a suite of autapomorphies in its vertebrae that include the relative proportions of cervicals three and four and the presence of elongated prezygapophyseal pedicles. The new taxon is interesting in that it lived contemporaneously with gigantic forms, comparable in size to the famous Romanian Hatzegopteryx thambema. The presence of two distinct azhdarchid size classes in a continental depositional environment further strengthens suggestions that these pterosaurs were strongly linked to terrestrial floodplain and wooded environments. To support this discussion, we outline the geological context and taphonomy of our new specimen and place it in context with other known records for this widespread and important Late Cretaceous pterosaurian lineage. PMID:23382886

A modeling study of the effect of gravity on airflow distribution and particle deposition in the lung.

PubMed

Asgharian, Bahman; Price, Owen; Oberdörster, Gunter

2006-06-01

Inhalation of particles generated as a result of thermal degradation from fire or smoke, as may occur on spacecraft, is of major health concern to space-faring countries. Knowledge of lung airflow and particle transport under different gravity environments is required to addresses this concern by providing information on particle deposition. Gravity affects deposition of particles in the lung in two ways. First, the airflow distribution among airways is changed in different gravity environments. Second, particle losses by sedimentation are enhanced with increasing gravity. In this study, a model of airflow distribution in the lung that accounts for the influence of gravity was used for a mathematical description of particle deposition in the human lung to calculate lobar, regional, and local deposition of particles in different gravity environments. The lung geometry used in the mathematical model contained five lobes that allowed the assessment of lobar ventilation distribution and variation of particle deposition. At zero gravity, it was predicted that all lobes of the lung expanded and contracted uniformly, independent of body position. Increased gravity in the upright position increased the expansion of the upper lobes and decreased expansion of the lower lobes. Despite a slight increase in predicted deposition of ultrafine particles in the upper lobes with decreasing gravity, deposition of ultrafine particles was generally predicted to be unaffected by gravity. Increased gravity increased predicted deposition of fine and coarse particles in the tracheobronchial region, but that led to a reduction or even elimination of deposition in the alveolar region for coarse particles. The results from this study show that existing mathematical models of particle deposition at 1 G can be extended to different gravity environments by simply correcting for a gravity constant. Controlled studies in astronauts on future space missions are needed to validate these predictions.

Room model based Monte Carlo simulation study of the relationship between the airborne dose rate and the surface-deposited radon progeny.

PubMed

Sun, Kainan; Field, R William; Steck, Daniel J

2010-01-01

The quantitative relationships between radon gas concentration, the surface-deposited activities of various radon progeny, the airborne radon progeny dose rate, and various residential environmental factors were investigated through a Monte Carlo simulation study based on the extended Jacobi room model. Airborne dose rates were calculated from the unattached and attached potential alpha-energy concentrations (PAECs) using two dosimetric models. Surface-deposited (218)Po and (214)Po were significantly correlated with radon concentration, PAECs, and airborne dose rate (p-values <0.0001) in both non-smoking and smoking environments. However, in non-smoking environments, the deposited radon progeny were not highly correlated to the attached PAEC. In multiple linear regression analysis, natural logarithm transformation was performed for airborne dose rate as a dependent variable, as well as for radon and deposited (218)Po and (214)Po as predictors. In non-smoking environments, after adjusting for the effect of radon, deposited (214)Po was a significant positive predictor for one dose model (RR 1.46, 95% CI 1.27-1.67), while deposited (218)Po was a negative predictor for the other dose model (RR 0.90, 95% CI 0.83-0.98). In smoking environments, after adjusting for radon and room size, deposited (218)Po was a significant positive predictor for one dose model (RR 1.10, 95% CI 1.02-1.19), while a significant negative predictor for the other model (RR 0.90, 95% CI 0.85-0.95). After adjusting for radon and deposited (218)Po, significant increases of 1.14 (95% CI 1.03-1.27) and 1.13 (95% CI 1.05-1.22) in the mean dose rates were found for large room sizes relative to small room sizes in the different dose models.

National uranium resource evaluation: Newark Quadrangle, Pennsylvania and New Jersey

DOE Office of Scientific and Technical Information (OSTI.GOV)

Popper, G.H.P.; Martin, T.S.

1982-04-01

The Newark Quadrangle, Pennsylvania and New Jersey, was evaluated to a depth of 1500 m to identify geologic environments and delineate areas favorable for uranium deposits. Criteria used were those developed for the National Uranium Resource Evaluation program. Results of the investigation indicate that the Precambrian Reading Prong contains environments favorable for anatectic and allogenic uranium deposits. Two suites of rocks are favorable for anatectic-type concentrations: An alaskite-magnetite-gneiss association, and red granite and quartz monzonite. Allogenic uranium concentrations occur in rocks of the marble-skarn-serpentinite association. Environments favorable for peneconcordant sandstone-type uranium deposits occur in the upper one-third of the Catskillmore » Formation, the Mississippian-Pennsylvanian Mauch Chunk-Pottsville transition beds, and the upper half of the Triassic Stockton Formation. The Triassic Lockatong Formation contains environments favorable for carbonaceous shale-type uranium concentrations. The Ordovician Epler Formation and the Cretaceous-Tertiary strata of the Coastal Plain were not evaluated due to time restrictions and lack of outcroup. All other geologic environments are considered unfavorable for uranium deposits.« less

Analysis on the overpressure characterization with respect to depositional environment facies: Case Study in Miri Area, Baram Delta

NASA Astrophysics Data System (ADS)

Mhd Hanapiah, N.; Yusoff, W. I. Wan; Zakariah, M. N. A.

2017-10-01

Overpressure studies in oil and gas exploration and production are carried out in order to mitigate any losses that could happen while drilling. These concerns can be addressed by enhancing the understanding of overpressure characterization in the fields. This research emphasizes in determining the pore pressure trend in Miri area to assist pore pressure prediction for future hydrocarbon exploration and production. Generally, pore pressure trends are related to mechanisms that contribute to the overpressure generation. In the region predominant overpressure are disequilibrium compaction within the prodelta shales meanwhile in outer shelf overpressure generation controlled by fluid expansion in deltaic sequence of inner shelf area. The objective of this research is to analyze the pore pressure profile of wells for determining vertical trends of pore pressure for various depositional environment facies of Miri area. Integration of rock physics and pore pressure analysis and relating the trends to environment depositional environment facies within shale underlying sand interval. Analysis done shows that overpressure top is characterize by depositional environment facies within shale underlying sand interval.

Physico-chemical characterisation of glass soiling in rural, urban and industrial environments.

PubMed

Lombardo, T; Chabas, A; Verney-Carron, A; Cachier, H; Triquet, S; Darchy, S

2014-01-01

Glass materials are broadly used in the built environment (windows, facades, roofs, museum showcases, and solar panels) due to their optical (transparency) and thermal properties. Their interaction with the multiphase atmospheric medium results in a more or less pronounced transparency loss called soiling. This phenomenon leads to a loss of amenity of artefacts; consequently, high cleaning costs have to be supported by public and private entities. Complete understanding of the nature of surface deposit appears thus extremely important for addressing strategies to control it. The present research is based on the sheltered exposure, in different environments, of durable glass panels during 1 year. At these different locations, airborne pollutant concentrations have also been monitored. Three environments have been investigated: rural (R), urban (U) and industrial (I). Results show that the mass of the deposit and the optical impairment of the glass (haze) are too spread to allow discriminating between different environments. However, the analyses of soluble species and particulate organic matter allow identifying factors responsible for soiling and highlighted the reactivity of deposit to relative humidity which favours post-deposit evolution.

A genetic model based on evapoconcentration for sediment-hosted exotic-Cu mineralization in arid environments: the case of the El Tesoro Central copper deposit, Atacama Desert, Chile

NASA Astrophysics Data System (ADS)

Fernández-Mort, A.; Riquelme, R.; Alonso-Zarza, A. M.; Campos, E.; Bissig, T.; Mpodozis, C.; Carretier, S.; Herrera, C.; Tapia, M.; Pizarro, H.; Muñoz, S.

2017-12-01

Although the formation of exotic-Cu deposits is controlled by multiple factors, the role of the sedimentary environment has not been well defined. We present a case study of the El Tesoro Central exotic-Cu deposit located in the Atacama Desert of northern Chile. This deposit consists of two mineralized bodies hosted within Late Cenozoic gravels deposited in an arid continental environment dominated by alluvial fans with sub-surficial ponded water bodies formed at the foot of these fans or within the interfan areas. Both exotic-Cu orebodies mostly consist of chrysocolla, copper wad, atacamite, paratacamite, quartz, opal, and calcite. The most commonly observed paragenesis comprises chrysocolla, silica minerals, and calcite and records a progressive increase in pH, which is notably influenced by evaporation. The results of stable isotope analyses (δ13C and δ18O) and hydrogeochemical simulations confirm that evapoconcentration is the main controlling factor in the exotic-Cu mineralization at El Tesoro Central. This conclusion complements the traditional genetic model based on the gradual neutralization of highly oversaturated Cu-bearing solutions that progressively cement the gravels and underlying bedrock regardless of the depositional environment. This study concludes that in exotic-Cu deposits formed relatively far from the source, a favorable sedimentary environment and particular hydrologic and climatic conditions are essential to trap, accumulate, evapoconcentrate, neutralize and saturate Cu-bearing solutions to trigger mineralization. Thus, detailed sedimentological studies should be incorporated when devising exploration strategies in order to discover new exotic-Cu resources, particularly if they are expected to have formed relatively far from the metal sources.

In situ electric properties of Ag films deposited on rough substrates

NASA Astrophysics Data System (ADS)

Zhou, Hong; Yu, Sen-Jiang; Zhang, Yong-Ju; Chen, Miao-Gen; Jiao, Zhi-Wei; Si, Ping-Zhan

2013-01-01

Silver (Ag) films have been deposited on rough substrates (including frosted glass and silicone grease), and for comparison on flat glass, by DC-magnetron sputtering, and their sheet resistances measured in situ during deposition. It is found that the growth of Ag films proceeds through three distinct stages: discontinuous, semi-continuous, and continuous regimes. The sheet resistance on rough substrates jumps in the vicinity of the percolation threshold, whereas the resistance on flat substrates decreases monotonically during deposition. The abnormal in situ electric properties on rough substrates are well explained based on the differences of the growth mechanism and microstructure of Ag films on different substrates.

Nanostructured carbon films with oriented graphitic planes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Teo, E. H. T.; Kalish, R.; Kulik, J.

2011-03-21

Nanostructured carbon films with oriented graphitic planes can be deposited by applying energetic carbon bombardment. The present work shows the possibility of structuring graphitic planes perpendicular to the substrate in following two distinct ways: (i) applying sufficiently large carbon energies for deposition at room temperature (E>10 keV), (ii) utilizing much lower energies for deposition at elevated substrate temperatures (T>200 deg. C). High resolution transmission electron microscopy is used to probe the graphitic planes. The alignment achieved at elevated temperatures does not depend on the deposition angle. The data provides insight into the mechanisms leading to the growth of oriented graphiticmore » planes under different conditions.« less

Use of the Cone Penetration Testing (CPT) method to interpret late Quaternary tide-dominated successions: A case study from the eastern China coastal plain

NASA Astrophysics Data System (ADS)

Zhang, Xia; Lin, Chun-Ming; Dalrymple, Robert W.; Gao, Shu; Canas, Daniel T.

2018-06-01

We evaluate the applicability of cone penetration testing (CPT), calibrated using adjacent cores, as a tool for the sedimentological and stratigraphic examination of late Quaternary tide-dominated successions in the eastern China coastal plain. The results indicate that the sedimentary facies and sequence-stratigraphic surfaces can be readily distinguished using CPT profiles in the Qiantang River incised-valley system because of their distinctive mechanical behavior. The lithologic character of the various facies, which is controlled mainly by sediment supply, dynamic processes and post-depositional diagenesis, is the key factor affecting how well the CPT technique works. Within this particular macrotidal environment, which is dominated by non-cohesive sand and silt in the tidal channels, the accumulation of fluid mud is rare. Consequently, the tidal-channel deposits exhibit the geotechnical properties of coarse-grained sediments, and can be easily distinguished from the mud-dominated facies. However, in the nearby Changjiang delta system which is characterized by very high suspended-sediment concentrations and an abundance of fine-grained cohesive sediments, the presence of channel-bottom fluid muds makes it difficult to recognize channel deposits, because of the lack of a sharp lithologic contrast at their base. Consequently, the CPT method might not be as universally effective in tide-dominated systems as it appears to be in wave-dominated settings. Care is needed in the interpretation of the results from tide-dominated successions because of the widespread presence of fluid muds, the heterolithic nature of tidal deposits, the rheological similarity between adjacent facies, and the averaging of geotechnical properties between the alternating finer and coarser layers.

Petrology, sedimentology and stratigraphic implications of Black Dragon Member of the Triassic Moenkopi Formation, San Rafael Swell, Utah

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chan, M.A.; Ochs, S.

1990-01-01

Deposition was partly controlled by paleotopographic relief of underlying Permian strata. Triassic Black Dragon sediments filled lowlands on an erosion surface (unconformity) cut into the Permian White Rim Sandstone and Kaibab Limestone. The Black Dragon Member consists of four distinct facies containing a wide variety of sedimentary structures that characterize both fluvial and tidal environments. The facies are: (1) a Chert Pebble Conglomerate (CPC) facies, characterized by calcite-cemented channel-fills of nodular and banded chert pebbles; (2) an Interbedded Sandstone, Siltstone, and Shale (SSS) facies, containing oscillation ripples and flaser bedding; (3) a large-scale Trough Cross-Stratified Sandstone (TXS) facies, consisting ofmore » 6.6-13.1 ft (2-4 m) thick sets of fine- to medium-grained sandstone; and (4) an Oolitic and Algal Limestone (OAL) facies, with cross-stratified oolitic beds, fenestral fabric, and laminated algal rip-up clasts. The CPC facies and the TXS facies were deposited by braided streams when the shoreline lay west of the San Rafael Swell. Rivers drained off and eroded localized Permian highlands, located most likely within a 62 mi (100 km) distance to the south and southeast of the study area. The SSS facies which constitutes the bulk of the Black Dragon Member, and the OAL facies are inter- and supratidal deposits formed during relative sea level highstands, when the shoreline lay within or east of the San Rafael Swell. A decrease in continent-derived sand supply and a corresponding increase in carbonate production within the OAL facies characterizes the end of Black Dragon deposition and the gradation into the overlying Sinbad Limestone Member.« less

Identification of third-order (approx. 10{sup 6} yrs) and fourth-order (approx. 10{sup 5}/10{sup 4} yrs) stratigraphic cycles in the South Addition, West Cameron Lease Area, Louisiana offshore

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lowrie, A.; Meeks, P.; Hoffman, K.

In the highly explored South Addition of the West Cameron Lease Area, Louisiana offshore, interpretation of a six-mile ({approx}10 km) seismic section across a single intraslope basin yielded 20 sediment packages. Several interpretive tools were necessary. Seismic stratigraphy indicated that the shallower zone was an outer shelf marked by 8 major sea level oscillations. In the portion between 1 and 3 seconds, seismic stratigraphy and paleontology led to the interpretation of depositional environments such as upper slope, and paleobathymetrically deeper intervals with descent through the section. The intraslope basin, while small, may be viewed as a micro-continental margin. Each seamore » level oscillation cycle apparently made a distinct progradational unit, decipherable in the seismic data. Fourth order cycles have been provisionally interpreted, throughout most of the entire 3.7 second section. Such precision is possible only in explored basins with excellent seismic data. The sequence thickness showed a seven-fold variability, from 0.08 to 0.58 seconds. The shallower section, deposited along an outer shelf, has an average individual sequence thickness of 0.13 seconds. Individual seismic sequences in the deeper section, interpreted to have been deposited on an upper slope, have average thicknesses of 0.25 seconds. The thinner sequences of the shallower section are compatible with the notion that the outer shelf was a bypass zone during a glacial epoch. The thicker sequences of the deeper section are the result of deposition onto an aggrading upper slope within an intraslope basin during a highstand.« less

Discriminating between natural and anthropogenic features of the sedimentary record in the coastal Beaufort Sea

NASA Astrophysics Data System (ADS)

Trefry, J. H.; Trocine, R. P.; Fox, A. L.; Fox, S. L.; Durell, G.; Kasper, J.

2016-02-01

The coastal Beaufort Sea is at a crossroads with respect to the impacts of human activities. Accurate discrimination of regional and global anthropogenic impacts, versus those due to natural physical and biogeochemical processes, is an important tool for managing environmental issues in the Arctic. We have investigated several natural and anthropogenic features in age-dated sediment cores from the coastal Beaufort Sea. For example, Hg enrichment (by 20 to >50% or +20 to 40 ng/g) was identified in some surface sediments using Hg/Al ratios in cores from nearshore, outer shelf and slope environments. Nearshore Hg anomalies, although quite limited in number, have been linked to drilling fluids deposited during oil and gas exploration in the 1980s. In contrast, similar offshore Hg anomalies are likely due to natural sediment diagenesis as previously noted by others in the deeper Arctic Ocean. We also found Ba enrichment in surface sediments that can be best explained by the deposition of natural, Ba-rich suspended particles from the Colville River; yet, Ba enrichment can sometimes be explained by the presence of drilling fluids in sediments near historic drilling sites. Human induced diagenetic changes are likely to follow current increases in river runoff and coastal erosion. Higher deposition rates for sediment and organic carbon in the coastal Beaufort Sea may create future anomalies for As, Cd and other metals. For example, metal anomalies can presently be found in older subsurface sediments where a layer of carbon-rich sediment was previously deposited. Correct identification of natural versus anthropogenic forcing factors that lead to distinct diagenetic features in the sedimentary record will help us to identify problem areas and make informed regulatory decisions.

Reservoir compartmentalization of deep-water Intra Qua Iboe sand (Pliocene), Edop field, offshore Nigeria

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hermance, W.E.; Olaifa, J.O.; Shanmugam, G.

An integration of 3-D seismic and sedimentological information provides a basis for recognizing and mapping individual flow units within the Intra Qua Iboe (IQI) reservoir (Pliocene), Edop Field, offshore Nigeria. Core examination show the following depositional facies: A-Sandy slump/mass flow, B-Muddy slump/mass flow, C. Bottom current reworking. D-Non-channelized turbidity currents, E. Channelized (coalesced) turbidity currents. F-Channelized (isolated) turbidity currents, G-Pelagic/hemipelagic, H-Levee, I-Reworked slope, J-Wave dominated, and K-Tide dominated facies. With the exception of facies J and K, all these facies are of deep-water affinity. The IQI was deposited on an upper slope environment in close proximity to the shelf edge.more » Through time, as the shelf edge migrated scaward, deposition began with a channel dominated deep-water system (IQI 1 and 2) and progressed through a slump/debris flow dominated deep-water system (IQI 3, the principle reservoir) to a tide and wave dominated shallow-water system (IQI 4). Compositional and textural similarities between the deep-water facies result in similar log motifs. Furthermore, these depositional facies are not readily apparent as distinct seismic facies. Deep-water facies A, D, E, and F are reservoir facies, whereas facies B, C, G, H, and I are non-reservoir facies. However, Facies G is useful as a seismically mappable event throughout the study area. Mapping of these non-reservoir events provides the framework for understanding gross reservoir architecture. This study has resulted in seven defined reservoir units within the IQI, which serves as the architectural framework for ongoing reservoir characterization.« less

Dust deposition and removal at the MER landing sites from observations of the Panoramic Camera (Pancam) calibration targets

NASA Astrophysics Data System (ADS)

Kinch, K. M.; Bell, J. F.; Madsen, M. B.

2012-12-01

The Panoramic Cameras (Pancams) [1] on NASA's Mars Exploration Rovers have each returned in excess of 17000 images of their external calibration targets (caltargets), a set of optically well-characterized patches of materials with differing reflectance properties. During the mission dust deposition on the caltargets changed their optical reflectance properties [2]. The thickness of dust on the caltargets can be derived with high confidence from the contrast between brighter and darker colored patches. The dustier the caltarget the less contrast. We present a new history of dust deposition and removal at the two MER landing sites. Our data reveals two quite distinct dust environments. At the Spirit landing site half the Martian year is dominated by dust deposition, the other half by dust removal that usually happens during brief sharp wind events. At the Opportunity landing site the Martian year has a four-season cycle of deposition-removal-deposition-removal with dust removal happening gradually throughout the two removal seasons. Comparison to atmospheric optical depth measurements [3] shows that dust removals happen during dusty high-wind periods and that dust deposition rates are roughly proportional to the atmospheric dust load. We compare with dust deposition studies from other Mars landers and also present some early results from observation of dust on a similar camera calibration target on the Mars Science Laboratory mission. References: 1. Bell, J.F., III, et al., Mars Exploration Rover Athena Panoramic Camera (Pancam) investigation. J. Geophys. Res., 2003. 108(E12): p. 8063. 2. Kinch, K.M., et al., Dust Deposition on the Mars Exploration Rover Panoramic Camera (Pancam) Calibration Targets. J. Geophys. Res., 2007. 112(E06S03): p. doi:10.1029/2006JE002807. 3. Lemmon, M., et al., Atmospheric Imaging Results from the Mars Exploration Rovers: Spirit and Opportunity. Science, 2004. 306: p. 1753-1756. Deposited dust optical depth on the Pancam caltargets as a function of time. The lower x-axes show sol number, the upper x-axes shows the areocentric longitude of the sun, Ls. Data shown are from caltarget observations with solar incidence angle i < 45°. Left column is Spirit. Right column is Opportunity. Top row shows our derived deposited optical depth in the L5 (535 nm) filter. Bottom row shows the atmospheric optical depth in the L8 (440 nm) filter as reported by the MER atmospheric team [3].

Chlorine-36 as a tracer of perchlorate origin

USGS Publications Warehouse

Sturchio, N.C.; Caffee, M.; Beloso, Abelardo D.; Heraty, L.J.; Böhlke, J.K.; Hatzinger, P.B.; Jackson, W.A.; Gu, B.; Heikoop, J.M.; Dale, M.

2009-01-01

Perchlorate (ClO4-) is ubiquitous in the environment. It is produced naturally by atmospheric photochemical reactions, and also is synthesized in large quantities for military, aerospace, and industrial applications. Nitrate-enriched salt deposits of the Atacama Desert (Chile) contain high concentrations of natural ClO4-, and have been exported worldwide since the mid-1800s for use in agriculture. The widespread introduction of synthetic and agricultural ClO4- into the environment has contaminated numerous municipal water supplies. Stable isotope ratio measurements of Cl and O have been applied for discrimination of different ClO4- sources in the environment. This study explores the potential of 36Cl measurements for further improving the discrimination of ClO4- sources. Groundwater and desert soil samples from the southwestern United States (U.S.) contain ClO4- having high 36Cl abundances (36Cl/Cl = 3100 ?? 10-15 to 28,800 ?? 10 -15), compared with those from the Atacama Desert (36Cl/Cl = 0.9 ?? 10-15 to 590 ?? 10-15) and synthetic ClO4- reagents and products (36Cl/Cl = 0.0 ?? 10-15 to 40 ?? 1015). In conjunction with stable Cl and O isotope ratios, 36Cl data provide a clear distinction among three principal. ClO4- source types in the environment of the southwestern U.S. ?? 2009 American Chemical Society.

Modern sedimentary environments in Boston Harbor, Massachusetts

USGS Publications Warehouse

Knebel, H.J.; Rendigs, R. R.; Bothner, Michael H.

1991-01-01

Analyses of sidescan-sonar records supplemented by available bathymetric, sedimentary, subbottom, and bottom-current data reveal the distributions of the following three categories of sedimentary environments within the glaciated, topographically complex Boston Harbor estuary in Massachusetts. 1) Environments of erosion appear on the sonographs either as patterns with isolated strong reflections or as uniform patterns of strong reflectivity. These patterns define outcrops of bedrock or till and coarse lag deposits that are being scoured and winnowed by tidal- and wave-induced currents. Erosional areas are located primarily along mainland and insular shores, within large channels that have strong tidal currents, atop submerged ridges and knolls, and across much of the harbor entrance. 2) Environments of deposition are depicted on the sidescan-sonar records as smooth, featureless surfaces that have low to moderate reflectivity. Depositional environments are found predominantly over shallow subtidal flats and in broad bathymetric lows where tidal currents are weak. Sediments within depositional areas are organic-rich sandy and clayey silts that are accumulating at rates ranging from 0.01 to 0.11 g/cm 2 /yr or 4000 to 46,100 metric tons/yr. The cumulative mass of modern mud in harbor depocenters is 24.3 million metric tons. 3) Environments of sediment reworking constitute areas affected by a combination of erosional and depositional processes. They are characterized on the sonographs by mosaics of light and dark patches produced by relatively subtle and gradational changes in reflectivity. Reworked sediments have diverse grain sizes that overlap and are transitional between those of the other two sedimentary environments, and they are indicative of highly variable bottom currents.

Microbial communities associated with wet flue gas desulfurization systems

PubMed Central

Brown, Bryan P.; Brown, Shannon R.; Senko, John M.

2012-01-01

Flue gas desulfurization (FGD) systems are employed to remove SOx gasses that are produced by the combustion of coal for electric power generation, and consequently limit acid rain associated with these activities. Wet FGDs represent a physicochemically extreme environment due to the high operating temperatures and total dissolved solids (TDS) of fluids in the interior of the FGD units. Despite the potential importance of microbial activities in the performance and operation of FGD systems, the microbial communities associated with them have not been evaluated. Microbial communities associated with distinct process points of FGD systems at several coal-fired electricity generation facilities were evaluated using culture-dependent and -independent approaches. Due to the high solute concentrations and temperatures in the FGD absorber units, culturable halothermophilic/tolerant bacteria were more abundant in samples collected from within the absorber units than in samples collected from the makeup waters that are used to replenish fluids inside the absorber units. Evaluation of bacterial 16S rRNA genes recovered from scale deposits on the walls of absorber units revealed that the microbial communities associated with these deposits are primarily composed of thermophilic bacterial lineages. These findings suggest that unique microbial communities develop in FGD systems in response to physicochemical characteristics of the different process points within the systems. The activities of the thermophilic microbial communities that develop within scale deposits could play a role in the corrosion of steel structures in FGD systems. PMID:23226147

Tectono-sedimentary analysis using the anisotropy of magnetic susceptibility: a study of the terrestrial and freshwater Neogene of the Orava Basin

NASA Astrophysics Data System (ADS)

Łoziński, Maciej; Ziółkowski, Piotr; Wysocka, Anna

2017-10-01

The Orava Basin is an intramontane depression filled with presumably fine-grained sediments deposited in river, floodplain, swamp and lake settings. The basin infilling constitutes a crucial record of the neoalpine evolution of the Inner/Outer Carpathian boundary area since the Neogene, when the Jurassic-Paleogene basement became consolidated, uplifted and eroded. The combination of sedimentological and structural studies with anisotropy of magnetic susceptibility (AMS) measurements provided an effective tool for recognition of terrestrial environments and deformations of the basin infilling. The lithofacies-oriented sampling and statistical approach to the large dataset of AMS specimens were utilized to define 12 AMS facies based on anisotropy degree (P) and shape (T). The AMS facies allowed a distinction of sedimentary facies ambiguous for classical methods, especially floodplain and lacustrine sediments, as well as revealing their various vulnerabilities to tectonic modification of AMS. A spatial analysis of facies showed that tuffites along with lacustrine and swamp deposits were generally restricted to marginal and southern parts of the basin. Significant deformations were noticed at basin margins and within two intrabasinal tectonic zones, which indicated the tectonic activity of the Pieniny Klippen Belt after the Middle Miocene. The large southern area of the basin recorded consistent N-NE trending compression during basin inversion. This regional tectonic rearrangement resulted in a partial removal of the southernmost basin deposits and shaped the basin's present-day extent.

Splint coals of the Central Appalachians: Petrographic and geochemical facies of the Peach Orchard No. 3 split coal bed, southern Magoffin County, Kentucky

USGS Publications Warehouse

Hower, James C.; Ruppert, Leslie F.

2011-01-01

The Bolsovian (Middle Pennsylvanian) Peach Orchard coal bed is one of the splint coals of the Central Appalachians. Splint coal is a name for the dull, inertinite-rich lithologies typical of coals of the region. The No. 3 Split was sampled at five locations in Magoffin County, Kentucky and analyzed for petrography and major and minor elements. The No. 3 Split coals contain semifusinite-rich lithologies, up to 48% (mineral-free basis) in one case. The nature of the semifusinite varies with position in the coal bed, containing more mineral matter of detrital origin in the uppermost durain. The maceral assemblage of these terminal durains is dominated by detrital fusinite and semifusinite, suggesting reworking of the maceral assemblage coincident with the deposition of the detrital minerals. However, a durain in the middle of the coal bed, while lithologically similar to the uppermost durains, has a degraded, macrinite-rich, texture. The inertinite macerals in the middle durain have less distinct edges than semifusinites in the uppermost terminal durains, suggesting degradation as a possible path to inertinite formation. The uppermost durain has higher ash and semifusinite contents at the eastern sites than at the western sites. The difference in the microscopic petrology indicates that megascopic petrology alone can be a deceptive indicator of depositional environments and that close attention must be paid to the individual macerals and their implications for the depositional setting, especially within the inertinite group.

Effect of oxygen concentration on the magnetic properties of La2CoMnO6 thin films

NASA Astrophysics Data System (ADS)

Guo, H. Z.; Gupta, A.; Zhang, Jiandi; Varela, M.; Pennycook, S. J.

2007-11-01

The dependence of the magnetic properties on oxygen concentration in epitaxial La2CoMnO6 thin films deposited on (100)-oriented SrTiO3 substrates has been investigated by varying the oxygen background pressure during growth using pulsed laser deposition. Two distinct ferromagnetic (FM) phases are revealed, and the relative fraction varies with the oxygen concentration. The existence of oxygen vacancies induces the local vibronic Mn3+-O -Co3+ superexchange interactions in direct competition with the static FM Mn4+-O-Co2+ interactions. This results in the appearance of a new low temperature FM phase and suppression of the high-temperature FM phase, creating two distinct magnetic phase transitions.

Dense Deposit Disease Mimicking a Renal Small Vessel Vasculitis

PubMed Central

Singh, Lavleen; Bhardwaj, Swati; Sinha, Aditi; Bagga, Arvind; Dinda, Amit

2016-01-01

Dense deposit disease is caused by fluid-phase dysregulation of the alternative complement pathway and frequently deviates from the classic membranoproliferative pattern of injury on light microscopy. Other patterns of injury described for dense deposit disease include mesangioproliferative, acute proliferative/exudative, and crescentic GN. Regardless of the histologic pattern, C3 glomerulopathy, which includes dense deposit disease and C3 GN, is defined by immunofluorescence intensity of C3c two or more orders of magnitude greater than any other immune reactant (on a 0–3 scale). Ultrastructural appearances distinguish dense deposit disease and C3 GN. Focal and segmental necrotizing glomerular lesions with crescents, mimicking a small vessel vasculitis such as ANCA-associated GN, are a very rare manifestation of dense deposit disease. We describe our experience with this unusual histologic presentation and distinct clinical course of dense deposit disease, discuss the pitfalls in diagnosis, examine differential diagnoses, and review the relevant literature. PMID:26361799

Global deposition of airborne dioxin.

PubMed

Booth, Shawn; Hui, Joe; Alojado, Zoraida; Lam, Vicky; Cheung, William; Zeller, Dirk; Steyn, Douw; Pauly, Daniel

2013-10-15

We present a global dioxin model that simulates one year of atmospheric emissions, transport processes, and depositions to the earth's terrestrial and marine habitats. We map starting emission levels for each land area, and we also map the resulting deposits to terrestrial and marine environments. This model confirms that 'hot spots' of deposition are likely to be in northern Europe, eastern North America, and in parts of Asia with the highest marine dioxin depositions being the northeast and northwest Atlantic, western Pacific, northern Indian Ocean and the Mediterranean. It also reveals that approximately 40% of airborne dioxin emissions are deposited to marine environments and that many countries in Africa receive more dioxin than they produce, which results in these countries being disproportionately impacted. Since human exposure to dioxin is largely through diet, this work highlights food producing areas that receive higher atmospheric deposits of dioxin than others. Copyright © 2013 Elsevier Ltd. All rights reserved.

Porphyry deposits of the Canadian Cordillera

USGS Publications Warehouse

McMillan, W.J.; Thompson, J.F.H.; Hart, C.J.R.; Johnston, S.T.

1996-01-01

Porphyry deposits are intrusion-related, large tonnage low grade mineral deposits with metal assemblages that may include all or some of copper, molybdenum, gold and silver. The genesis of these deposits is related to the emplacement of intermediate to felsic, hypabyssal, generally porphyritic intrusions that are commonly formed at convergent plate margins. Porphyry deposits of the Canadian Cordillera occur in association with two distinctive intrusive suites: calc-alkalic and alkalic. In the Canadian Cordillera, these deposits formed during two separate time periods: Late Triassic to Middle Jurassic (early Mesozoic), and Late Cretaceous to Eocene (Mesozoic-Cenozoic). Deposits of the early Mesozoic period occur in at least three different arc terranes (Wrangellia, Stikinia and Quesnellia) with a single deposit occurring in the oceanic assemblage of the Cache Creek terrane. These terranes were located outboard from continental North America during formation of most of their contained early Mesozoic porphyry deposits. Some of the deposits of this early period may have been emplaced during terrane collisions. Metal assemblages in deposits of the calc-alkalic suite include Mo-Cu (Brenda), Cu-Mo (Highland Valley, Gibraltar), Cu-Mo-Au-Ag (Island Copper, Schaft Creek) and Cu-Au (Kemess, Kerr).The alkalic suite deposits are characterized by a Cu-Au assemblage (Copper Mountain, Afton-Ajax, Mt. Milligan, Mount Polley, Galore Creek). Although silver is recovered from calc-alkalic and alkalic porphyry copper mining operations, silver data are seldom included in the published reserve figures. Those available are in the range of 1-2 grams per tonne (g??t-1). Alkalic suite deposits are restricted to the early Mesozoic and display distinctive petrology, alteration and mineralization that suggest a similar tectonic setting for both Quesnellia and Stikinia in Early Jurassic time. The younger deposits, late Mesozoic to Cenozoic in age, formed in an intracontinental setting, after the outboard host arc and related terranes accreted to the western margin of North America. These deposits are interpreted to occur in continental arc settings, and individual deposits are hosted by a variety of older country rocks. These younger deposits also show a spectrum of metal associations: Cu-Mo (Huckleberry, Berg), Cu-Au (-Mo) (Bell, Granisle, Fish Lake, Casino), Mo (Endako, Boss Mountain, Kit-sault, Quartz Hill), Mo-W (Logtung), Au-W (Dublin Gulch) and Au (Ft. Knox). There may be a continuum between Mo, Mo-W, Au-Mo-W and Au deposits. The distribution and timing of these post-accretion deposits likely reflect major crustal structures and subduction geometry. Cordilleran porphyry metallic deposits show the full range of morphological and depth relationships found in porphyry deposits worldwide. In addition, the Cordillera contains numerous alkalic suite deposits, which are rare worldwide: the unusual, possibly syntectonic Gibraltar deposit; and end-member gold-rich granite-hosted deposits, such as Ft. Knox (Alaska).

43 CFR 3486.3 - Enforcement.

Code of Federal Regulations, 2011 CFR

2011-10-01

... mine, the deposit being mined, valuable ore-bearing mineral deposits or other resources, or affect the... the authorized officer, and/or which threaten immediate and serious damage to the mine, the deposit being mined, valuable ore-bearing mineral deposits, or, regarding exploration, the environment, the...

Eocene climates, depositional environments, and geography, greater Green River basin, Wyoming, Utah, and Colorado

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roehler, H.W.

1993-12-31

The climates, depositional environments, and geography of Eocene rocks in the greater Green River basin are investigated to determine the origin, mode of deposition, and areal distribution of the Wasatch, Green River, Bridger, and Washakie Formations. The data indicate that Eocene climates ranged from cool temperature to tropical and were affected by both terrestrial and astronomical factors. The terrestrial factors were mainly latitude, altitude, regional geography, tectonism, and volcanism. The astronomical factors are interpreted from reptitious rock sequences in the Wilkins Peak Member of the Green River Formation that record seasonal changes, 21,000 year precession of the equinox cycles, 100,000more » year eccentricity cycles, and an undetermined cycle of 727,000 years. Eight depositional environments are identified, discussed, and illustrated by diagrams, columnar sections, and photographs. They are: (1) fluvial, (2) paludal, (3) freshwater lacustrine, (4) saltwater lacustrine, (5) pond and playa lake, (6) evaporite (salt pan), (7) mudflat, and (8) volcanic and fluviovolcanic. The areal distribution of the eight depositional environments in the Wasatch, Green River, Bridger, and Washakie Formations is illustrated by photographs and 13 paleogeographic maps. 76 refs., 90 figs.« less

Distribution of bacteria and associated minerals in the gill chamber of the vent shrimp Rimicaris exoculata and related biogeochemical processes

NASA Astrophysics Data System (ADS)

Zbinden, M.; Le Bris, N.; Compere, P.; Gaill, F.

2004-12-01

The shrimp Rimicaris exoculata dominates the megafauna of some mid-Atlantic Ridge hydrothermal vent fields. This species harbors a rich bacterial epibiosis inside its gill chamber. At the Rainbow vent field, the epibionts are associated with iron oxide deposits. Investigation of both bacteria and minerals by scanning electron microscopy (SEM) and X-ray microanalysis (EDX) shows the occurrence of three distinct compartments in the gill chamber: (1) the lower pre-branchial chamber, housing bacteria, but devoid of minerals, (2) the "true" branchial chamber that contains the gills and remains free of both bacteria and minerals, and (3) the upper pre-branchial chamber housing the main ectosymbiotic bacterial community and associated iron oxides. According to our chemical and temperature data, abiotic iron oxidation appears to be kinetically inhibited in the environment of the shrimps and this would explain the lack of iron oxide deposits in the first two areas. We propose that, in the third area, iron oxidation is microbially promoted. The discrepancy between the spatial distribution of bacteria and minerals suggests that different bacterial metabolisms are involved in the two compartments. A possible explanation lies in the modification of physico-chemical conditions downstream of the gills, that would reduce the oxygen content and favor the development of bacterial iron-oxidizers in this Fe II-rich environment. A potential role of such iron-oxidizing symbionts in the shrimp diet is suggested. This would be unusual for hydrothermal ecosystems, where most previously described symbioses rely on sulphide or methane as an energy source.

Atmospheric wet deposition of dissolved trace elements to Jiaozhou Bay, North China: Fluxes, sources and potential effects on aquatic environments.

PubMed

Xing, Jianwei; Song, Jinming; Yuan, Huamao; Wang, Qidong; Li, Xuegang; Li, Ning; Duan, Liqin; Qu, Baoxiao

2017-05-01

To analyze the fluxes, seasonal variations, sources and potential ecological effects of dissolved trace elements (TEs) in atmospheric wet deposition (AWD), one-year wet precipitation samples were collected and determined for nine TEs in Jiaozhou Bay (JZB) between June 2015 and May 2016. Both the volume-weighted mean (VWM) concentration and flux sequence for the measured TEs was Al > Mn > Zn > Fe > Pb > Se > Cr > Cd > Co. Al was the most abundant TE with a VWM concentration and wet flux of 33.8 μg L -1 and 29.2 mg m -2  yr -1 , which were 2 and 3 orders of magnitude higher than those of Co, respectively. The emission intensities of pollutants, rainfall amount and wind speed were the dominating factors influencing seasonal variations of TEs in AWD. Based on enrichment factors, correlation analysis and principal component analysis, most of the TEs in AWD were primarily originated from anthropogenic activities except for Al and Fe, which are typically derived from re-suspended soil dusts. Although the TE inputs by AWD were significantly lower than those by rivers, the TE inputs via short-term heavy rains would distinctly increase surface seawater TE concentrations and then pollute the marine environment of JZB. AWD would have both profound impacts on the biogeochemical cycles of TEs and dual ecological effects (nutrient and toxicity) on aquatic organisms. Copyright © 2017 Elsevier Ltd. All rights reserved.

Sedimentary Parameters Controlling Occurrence and Preservation of Microbial Mats in Siliciclastic Depositional Systems

NASA Technical Reports Server (NTRS)

Noffke, Nora; Knoll, Andrew H.

2001-01-01

Shallow-marine, siliciclastic depositional systems are governed by physical sedimentary processes. Mineral precipitation or penecontemporaneous cementation play minor roles. Today, coastal siliciclastic environments may be colonized by a variety of epibenthic, mat-forming cyanobacteria. Studies on microbial mats showed that they are not randomly distributed in modern tidal environments. Distribution and abundancy is mainly function of a particular sedimentary facies. Fine-grained sands composed of "clear" (translucent) quartz particles constitute preferred substrates for cyanobacteria. Mat-builders also favor sites characterized by moderate hydrodynamic flow regimes, which permit biomass enrichment and construction of mat fabrics without lethal burial of mat populations by fine sediments. A comparable facies relationship can be observed in ancient siliciclastic shelf successions from the terminal Neoproterozoic Nama Group, Namibia. Wrinkle structures that record microbial mats are present but sparsely distributed in mid- to inner shelf sandstones of the Nudaus Formation. The sporadic distribution of these structures reflects both the narrow ecological window that governs mat development and the distinctive taphonomic conditions needed to preserve the structures. These observations caution that statements about changing mat abundance across the Proterozoic-Cambrian boundary must be firmly rooted in paleoenvironmental and taphonomic analysis. Understanding the factors that influence the formation and preservation of microbial structures in siliciclastic regimes can facilitate exploration for biological signatures in Earth's oldest rocks. Moreover, insofar as these structures can be preserved on bedding surfaces and are not easily mimicked by physical processes, they constitute a set of biological markers that can be searched for on Mars by remotely controlled rovers.

Distinguishing palagonitized from pedogenically-altered basaltic Hawaiian tephra: Mineralogical and geochemical criteria

USGS Publications Warehouse

Schiffman, P.; Southard, R.J.; Eberl, D.D.; Bishop, J.L.

2002-01-01

Palagonitization is a common, but imperfectly defined process that greatly modifies the physical and chemical properties of glassy basaltic tephra deposited in subaquatic/subglacial environments on Earth and perhaps Mars. It also results in textures and mineralogies that are distinct from other forms of (mainly pedogenic) low temperature alteration. Specifically, the process of palagonitization (1) initially results in the formation of 'palaginitized glass', a quasi- or nano-crystalline, rind-like material that contains smectite, as well as lesser amounts of other clays (e.g. serpentine), and (2) eventually results in consolidation of tephra, mediated through the accretion of palagonitized glass and later- formed authigenic cements. Conversely, pedogenic weathering of glassy basaltic tephra is characterized by disaggregation of tephra, and formation of a wide range of pedogenic products, including layer silicates (although not primarily smectite), short-range-order aluminosilicates and oxyhydroxides, whose composition reflects the intensity of the weathering environment. These mineralogical and textural properties can be readily recognized through a variety of techniques including electron microscopy/microprobe analysis, reflectance spectroscopy, X-ray diffraction and soil chemistry. Analyses of samples collected from the summit regions of Kilauea and Mauna Kea volcanoes on the island of Hawaii are presented here in order to illustrate differences between palagonitization and pedogenic weathering of glassy basaltic tephra. In the young Hawaiian tephras studied, palagonitization has occured in response to hydrothermal activity shortly after deposition. Although some, non-hydrothermally affected tephras may eventually become palagonitized, those that have been strongly desilicated by intense pedogenic weathering will probably never become palagonitized.

Method of forming ultra thin film devices by vacuum arc vapor deposition

NASA Technical Reports Server (NTRS)

Schramm, Harry F. (Inventor)

2005-01-01

A method for providing an ultra thin electrical circuit integral with a portion of a surface of an object, including using a focal Vacuum Arc Vapor Deposition device having a chamber, a nozzle and a nozzle seal, depressing the nozzle seal against the portion of the object surface to create an airtight compartment in the chamber and depositing one or more ultra thin film layer(s) only on the portion of the surface of the object, the layers being of distinct patterns such that they form the circuit.

The metallogeny of Late Triassic rifting of the Alexander terrane in southeastern Alaska and northwestern British Columbia

USGS Publications Warehouse

Taylor, C.D.; Premo, W.R.; Meier, A.L.; Taggart, J.E.

2008-01-01

A belt of unusual volcanogenic massive sulfide (VMS) occurrences is located along the eastern margin of the Alexander terrane throughout southeastern Alaska and northwestern British Columbia and exhibits a range of characteristics consistent with a variety of syngenetic to epigenetic deposit types. Deposits within this belt include Greens Creek and Windy Craggy, the economically most significant VMS deposit in Alaska and the largest in North America, respectively. The occurrences are hosted by a discontinuously exposed, 800-km-long belt of rocks that consist of a 200- to 800-m-thick sequence of conglomerate, limestone, marine elastic sedimentary rocks, and tuff intercalated with and overlain by a distinctive unit of mafic pyroclastic rocks and pillowed flows. Faunal data bracket the age of the host rocks between Anisian (Middle Triassic) and late Norian (late Late Triassic). This metallogenic belt is herein referred to as the Alexander Triassic metallogenic belt. The VMS occurrences show systematic differences in degree of structural control, chemistry, and stratigraphic setting along the Alexander Triassic metallogenic belt that suggest important spatial or temporal changes in the tectonic environment of formation. At the southern end of the belt, felsic volcanic rocks overlain by shallow-water limestones characterize the lower part of the sequence. In the southern and middle portion of the belt, a distinctive pebble conglomerate marks the base of the section and is indicative of high-energy deposition in a near slope or basin margin setting. At the northern end of the belt the conglomerates, limestones, and felsic volcanic rocks are absent and the belt is composed of deep-water sedimentary and mafic volcanic rocks. This northward change in depositional environment and lithofacies is accompanied by a northward transition from epithermal-like structurally controlled, discontinuous, vein- and pod-shaped, Pb-Zn-Ag-Ba-(Cu) occurrences with relatively simple mineralogy, to sulfosalt-enriched VMS occurrences exhibiting characteristics of vein, diagenetic replacement, and exhalative styles of mineralization, and finally to Cu-Zn-(Co-Au) occurrences with larger and more clearly stratiform orebody morphologies. Occurrences in the middle of the belt are transitional in nature between structurally controlled types of mineralization that formed in a shallow-water, near-arc setting, to those having a more stratiform appearance, formed in a deeper water, rift-basin setting. The geologic setting in the south is consistent with shallow subaqueous emplacement on the flanks of the Alexander terrane. Northward, the setting changes to an increasingly deeper back- or intra-arc rift basin. Igneous activity in the Alexander Triassic metallogenic belt is characterized by a bimodal suite of volcanic rocks and a previously unrecognized association with mafic-ultramafic hypabyssal intrusions. Immobile trace and rare earth element (BEE) geochemical data indicate that felsic rocks in the southern portion of the belt are typical calc-alkaline rhyolites, which give way in the middle of the belt to peralkaline rhyolites. Rhyolites are largely absent in the northern part of the belt. Throughout the belt, the capping basaltic rocks have transitional geochemical signatures. Radiogenic isotope data for these rocks are also transitional (basalts and gabbros: ??-Nd = 4-9 and 87Sr/86Sr initial at 215 Ma = 0.7037-0.7074). Together these data are interpreted to reflect variable assimilation of mature island-arc crust by more primitive melts having the characteristics of either mid-ocean ridge (MORB) or intraplate (within-plate) basalts (WPB). The ore and host-rock geochemistry and the sulfosalt-rich mineralogy of the deposits are strikingly similar to recent descriptions of active sea-floor hydrothermal (white smoker) systems in back arcs of the southwest Pacific Ocean. These data, in concert with existing faunal ages, record the formation of a belt of VMS deposits

Depositional environments during the Late Palaeozoic ice age (LPIA) in northern Ethiopia, NE Africa

NASA Astrophysics Data System (ADS)

Bussert, Robert

2014-11-01

The Late Palaeozoic sediments in northern Ethiopia record a series of depositional environments during and after the Late Paleozoic ice age (LPIA). These sediments are up to 200 m thick and exceptionally heterogeneous in lithofacies composition. A differentiation of numerous types of lithofacies associations forms the basis for the interpretation of a large range of depositional processes. Major glacigenic lithofacies associations include: (1) sheets of diamictite, either overlying glacially eroded basement surfaces or intercalated into the sediment successions, and representing subglacial tillites, (2) thick massive to weakly stratified muddy clast-poor diamictites to lonestone-bearing laminated mudstones originating from a combination of suspension settling of fines and iceberg rainout, (3) lensoidal or thin-bedded diamictites deposited from debris flows, (4) wedges of traction and gravity transported coarse-grained sediments deposited in outwash fans, (5) irregular wedges or sheets of mudstones deformed primarily by extension and incorporating deformed beds or rafts of other lithofacies formed by slumping, and (6) irregular bodies of sandstone, conglomerate and diamictite deformed by glacial pushing. The dominance of laminated or massive clast-bearing mudstones in most successions indicates ice-contact water bodies as the major depositional environment. Into this environment, coarse-grained sediments were transported by various gravity driven transport processes, including dropstone activity of ice-bergs, slumping, cohesive debris flow, hyperconcentrated to concentrated flow, hyperpycnal flow, and by turbidity flow. Close to glacier termini, wedge-shaped bodies of conglomerate, sandstone, diamictite and mudstone were deposited primarily in subaqueous outwash-fans. Soft-sediment deformation of these sediments either records ice push during glacier advance or re-sedimentation by slumping. Apart from an initial glacier advance when thick ice of temperate or polythermal glaciers covered the whole basin, many sections document at least a second major phase of ice advance and retreat, and some sections additional minor advance-retreat cycles. Whether most of the LPIA sediments in northern Ethiopia were deposited in lakes or in fjords is not yet clear. Although univocal evidence of marine conditions is missing, the presence of carbonate-rich beds and the trace fossil assemblage are compatible with a restricted marine environment such as broad palaeofjords affected by strong freshwater discharge during deglaciation. A restricted marine environment for most of the sediments in northern Ethiopia could challenge models of the LPIA sediments in Arabia as primarily glaciolacustrine and glaciofluviatile deposits.

'Snake River (SR)-type' volcanism at the Yellowstone hotspot track: Distinctive products from unusual, high-temperature silicic super-eruptions

USGS Publications Warehouse

Branney, M.J.; Bonnichsen, B.; Andrews, G.D.M.; Ellis, B.; Barry, T.L.; McCurry, M.

2008-01-01

A new category of large-scale volcanism, here termed Snake River (SR)-type volcanism, is defined with reference to a distinctive volcanic facies association displayed by Miocene rocks in the central Snake River Plain area of southern Idaho and northern Nevada, USA. The facies association contrasts with those typical of silicic volcanism elsewhere and records unusual, voluminous and particularly environmentally devastating styles of eruption that remain poorly understood. It includes: (1) large-volume, lithic-poor rhyolitic ignimbrites with scarce pumice lapilli; (2) extensive, parallel-laminated, medium to coarse-grained ashfall deposits with large cuspate shards, crystals and a paucity of pumice lapilli; many are fused to black vitrophyre; (3) unusually extensive, large-volume rhyolite lavas; (4) unusually intense welding, rheomorphism, and widespread development of lava-like facies in the ignimbrites; (5) extensive, fines-rich ash deposits with abundant ash aggregates (pellets and accretionary lapilli); (6) the ashfall layers and ignimbrites contain abundant clasts of dense obsidian and vitrophyre; (7) a bimodal association between the rhyolitic rocks and numerous, coalescing low-profile basalt lava shields; and (8) widespread evidence of emplacement in lacustrine-alluvial environments, as revealed by intercalated lake sediments, ignimbrite peperites, rhyolitic and basaltic hyaloclastites, basalt pillow-lava deltas, rhyolitic and basaltic phreatomagmatic tuffs, alluvial sands and palaeosols. Many rhyolitic eruptions were high mass-flux, large volume and explosive (VEI 6-8), and involved H2O-poor, low-??18O, metaluminous rhyolite magmas with unusually low viscosities, partly due to high magmatic temperatures (900-1,050??C). SR-type volcanism contrasts with silicic volcanism at many other volcanic fields, where the fall deposits are typically Plinian with pumice lapilli, the ignimbrites are low to medium grade (non-welded to eutaxitic) with abundant pumice lapilli or fiamme, and the rhyolite extrusions are small volume silicic domes and coule??es. SR-type volcanism seems to have occurred at numerous times in Earth history, because elements of the facies association occur within some other volcanic fields, including Trans-Pecos Texas, Etendeka-Paran, Lebombo, the English Lake District, the Proterozoic Keewanawan volcanics of Minnesota and the Yardea Dacite of Australia. ?? Springer-Verlag 2007.

Analytical electron microscopy of biogenic and inorganic carbonates

NASA Technical Reports Server (NTRS)

Blake, David F.

1989-01-01

In the terrestrial sedimentary environment, the mineralogically predominant carbonates are calcite-type minerals (rhombohedral carbonates) and aragonite-type minerals (orthorhombic carbonates). Most common minerals precipitating either inorganically or biogenically are high magnesium calcite and aragonite. High magnesium calcite (with magnesium carbonate substituting for more than 7 mole percent of the calcium carbonate) is stable only at temperatures greater than 700 C or thereabouts, and aragonite is stable only at pressures exceeding several kilobars of confining pressure. Therefore, these carbonates are expected to undergo chemical stabilization in the diagenetic environment to ultimately form stable calcite and dolomite. Because of the strong organic control of carbonate deposition in organisms during biomineralization, the microchemistry and microstructure of invertebrate skeletal material is much different than that present in inorganic carbonate cements. The style of preservation of microstructural features in skeletal material is therefore often quite distinctive when compared to that of inorganic carbonate even though wholesale recrystallization of the sediment has taken place. Microstructural and microchemical comparisons are made between high magnesium calcite echinoderm skeletal material and modern inorganic high magnesium calcite inorganic cements, using analytical electron microscopy and related techniques. Similar comparisons are made between analogous materials which have undergone stabilization in the diagenetic environment. Similar analysis schemes may prove useful in distinguishing between biogenic and inorganic carbonates in returned Martian carbonate samples.

Geologic Evidence of Earthquakes and Tsunamis in the Mexican Subduction zone - Guerrero

NASA Astrophysics Data System (ADS)

Ramirez-Herrera, M.; Lagos, M.; Hutchinson, I.; Ruiz-Fernández, A.; Machain, M.; Caballero, M.; Rangel, V.; Nava, H.; Corona, N.; Bautista, F.; Kostoglodov, V.; Goguitchaichrili, A.; Morales, J.; Quintana, P.

2010-12-01

A study of large historic and prehistoric earthquakes and their tsunamis using a multiproxy approach (geomorphic features, sediment deposits, microfossils, sediment geochemistry and more recently the use of magnetic properties) has provided valuable information in the assessment of earthquake and tsunami record. The Pacific coast of Mexico is located over the active subduction zone (~1000 km) that has experienced numerous large magnitude earthquakes in historical time (Mw>7.5), and more than 50 documented tsunamis since 1732. Geomorphic and stratigraphic studies through test pits at 13 sites on the Guerrero coast reveal distinct stratigraphic changes with depth, indicating clear rapid change in depositional environments over time. Microfossil ecology (diatoms and foraminifera), sediment geochemistry (concentration increment in elements such as Sr, Ba, Ca, P, Si, K), stratigraphy, sediment magnetic properties (magnetic susceptibility anisotropy for the first time applied in tsunami deposits identification) and other proxies are indicative of sudden changes in land level and tsunami deposits. Buried evidence of liquefaction confirms the occurrence of a large earthquake at Barra de Potosi and Ixtapa, Guerrero. Preliminary 210Pb analysis suggests a sedimentation rate of ca. 0.1±0.01 cm/year and an estimated minimum age of ~ 100 years (maximum age at ca. 450 years?) for the most recent earthquake. At least three large events can be recognized by sharp contacts and sand layers in the sedimentary record. Ongoing C14, OSL and 210Pb dating will constrain the timing of these events. Deposits from three marine inwash events (tsunamis) dating from the past 4600 years have been identified on the Guerrero coast. A near-surface sand bed with a sharp basal contact overlying soil at sites near Ixtapa and Barra de Potosi most probably marks the tsunami following the 1985 Mw 8.2 earthquake. Interviews with Barra de Potosi fishermen and locals corroborate that these sites were inundated by this tsunami.

Integrated sequence stratigraphy of the postimpact sediments from the Eyreville core holes, Chesapeake Bay impact structure inner basin

USGS Publications Warehouse

Browning, J.V.; Miller, K.G.; McLaughlin, P.P.; Edwards, L.E.; Kulpecz, A.A.; Powars, D.S.; Wade, B.S.; Feigenson, M.D.; Wright, J.D.

2009-01-01

The Eyreville core holes provide the first continuously cored record of postimpact sequences from within the deepest part of the central Chesapeake Bay impact crater. We analyzed the upper Eocene to Pliocene postimpact sediments from the Eyreville A and C core holes for lithology (semiquantitative measurements of grain size and composition), sequence stratigraphy, and chronostratigraphy. Age is based primarily on Sr isotope stratigraphy supplemented by biostratigraphy (dinocysts, nannofossils, and planktonic foraminifers); age resolution is approximately ??0.5 Ma for early Miocene sequences and approximately ??1.0 Ma for younger and older sequences. Eocene-lower Miocene sequences are subtle, upper middle to lower upper Miocene sequences are more clearly distinguished, and upper Miocene- Pliocene sequences display a distinct facies pattern within sequences. We recognize two upper Eocene, two Oligocene, nine Miocene, three Pliocene, and one Pleistocene sequence and correlate them with those in New Jersey and Delaware. The upper Eocene through Pleistocene strata at Eyreville record changes from: (1) rapidly deposited, extremely fi ne-grained Eocene strata that probably represent two sequences deposited in a deep (>200 m) basin; to (2) highly dissected Oligocene (two very thin sequences) to lower Miocene (three thin sequences) with a long hiatus; to (3) a thick, rapidly deposited (43-73 m/Ma), very fi ne-grained, biosiliceous middle Miocene (16.5-14 Ma) section divided into three sequences (V5-V3) deposited in middle neritic paleoenvironments; to (4) a 4.5-Ma-long hiatus (12.8-8.3 Ma); to (5) sandy, shelly upper Miocene to Pliocene strata (8.3-2.0 Ma) divided into six sequences deposited in shelf and shoreface environments; and, last, to (6) a sandy middle Pleistocene paralic sequence (~400 ka). The Eyreville cores thus record the fi lling of a deep impact-generated basin where the timing of sequence boundaries is heavily infl uenced by eustasy. ?? 2009 The Geological Society of America.

Factors controlling localization of uranium deposits in the Dakota Sandstone, Gallup and Ambrosia Lake mining districts, McKinley County, New Mexico

USGS Publications Warehouse

Pierson, Charles Thomas; Green, Morris W.

1977-01-01

Geologic studies were made at all of the uranium mines and prospects in the Dakota Sandstone of Early(?) and Late Cretaceous age in the Gallup mining district, McKinley County, New Mexico. Dakota mines in the adjacent Ambrosia Lake mining district were visited briefly for comparative purposes. Mines in the eastern part of the Gallup district, and in the Ambrosia Lake district, are on the Chaco slope of the southern San Juan Basin in strata which dip gently northward toward the central part of the basin. Mines in the western part of the Gallup district are along the Gallup hogback (Nutria monocline) in strata which dip steeply westward into the Gallup sag. Geologic factors which controlled formation of the uranium deposits in the Dakota Sandstone are: (1) a source of uranium, believed to be uranium deposits of the underlying Morrison Formation of Late Jurassic age; (2) the accessibility to the Dakota of uranium-bearing solutions from the Morrison; (3) the presence in the Dakota of permeable sandstone beds overlain by impermeable carbonaceous shale beds; and (4) the occurrence within the permeable Dakota sandstone beds of carbonaceous reducing material as bedding-plane laminae, or as pockets of carbonaceous trash. Most of the Dakota uranium deposits are found in the lower part of the formation in marginal-marine distributary-channel sandstones which were deposited in the backshore environment. However, the Hogback no. 4 (Hyde) Mine (Gallup district) occurs in sandy paludal shale of the backshore environment, and another deposit, the Silver Spur (Ambrosia Lake district), is found in what is interpreted to be a massive beach or barrier-bar sandstone of the foreshore environment in the upper part of the Dakota. The sedimentary depositional environment most favorable for the accumulation of uranium is that of backshore areas lateral to main distributary channels, where levee, splay, and some distributary-channel sandstones intertongue with gray carbonaceous shales and siltstones of the well-drained swamp environment. Deposits of black carbonaceous shale which were formed in the poorly drained swamp deposits of the interfluve area are not favorable host rocks for uranium. The depositional energy levels of the various environments in which the sandstone and shale beds of the Dakota were deposited govern the relative favorability of the strata as uranium host rocks. In the report area, uranium usually occurs in carbonaceous sandstone deposited under low- to medium-energy fluvial conditions within distributary channels. A prerequisite, however, is that such sandstone be overlain by impermeable carbonaceous shale beds. Low- to medium-energy fluvial conditions result in the deposition of sandstone beds having detrital carbonaceous material distributed in laminae or in trash pockets on bedding planes. The carbonaceous laminae and trash pockets provide the necessary reductant to cause precipitation of uranium from solution. High-energy fluvial conditions result in the deposition of sandstones having little or no carbonaceous material included to provide a reductant. Very low energy swampy conditions result in carbonaceous shale deposits, which are generally barren of uranium because of their relative impermeability to migrating uranium-bearing solutions.

Stratigraphy of the Grande Savane Ignimbrite Sequence, Dominica, Lesser Antilles

NASA Astrophysics Data System (ADS)

Schneider, S.; Smith, A. L.; Deuerling, K.; Killingsworth, N.; Daly, G.

2007-12-01

The island of Dominica, located in the central part of the Lesser Antilles island arc has eight potentially active volcanoes. One of these, Morne Diablotins, is a composite stratovolcano with several superimposed stratigraphic sequences ranging in age from Pliocene (4-2 Ma) to "Younger" Pleistocene (<1.8 Ma). The most recent major eruptive activity from this volcano was a series of Plinian eruptions that produced ignimbrites that gave dates of >22,000 and >40,000 years B.P. The ignimbrite sequences form four flow fans that reached both the east and west coasts of the island. One of these flow fans, the Grande Savane, on the west coast of the island, also extends off-shore for a distance of at least 14 km as a distinctive submarine fan. Stratigraphical studies of the on- shore deposits that make up this fan indicate an older sequence of block and ash flow deposits, within which occurs a distinctive vulcanian fall deposit. These are overlain, with no evidence of an intervening paleosol, by a sequence of ignimbrites containing welded horizons (ranging in thickness from around 4 m to 16m). The lack of fall deposits beneath the ignimbrites suggest they may have been formed by instantaneous continuous collapse of the eruption column. This whole succession is overlain by a series of planar and dune bedded pumiceous surge deposits with interbedded pumiceous lapilli fall and ash fall deposits, that extend laterally outside of the main area of ignimbrite deposition. Beds within this upper sequence often contain accretionary lapilli and gas cavities suggesting magma-water interaction. The youngest deposits from Morne Diablotins appear to be valley- fill deposits of both ignimbrite and block and ash flow. A comparison of the of the Grande Savane pyroclastic sequence with the Pointe Ronde (west coast) and Londonderry (east coast) pyroclastic flow fans will provide information on the eruptive history of this major Plinian episode.

Structure, age and origin of the bay-mouth shoal deposits, Chesapeake Bay, Virginia

USGS Publications Warehouse

Colman, Steven M.; Berquist, C.R.; Hobbs, C. H.

1988-01-01

The mouth of Chesapeake Bay contains a distinctive shoal complex and related deposits that result from the complex interaction of three different processes: (1) progradation of a barrier spit at the southern end of the Delmarva Peninsula, (2) strong, reversing tidal currents that transport and rework sediment brought to the bay mouth from the north, and (3) landward (bayward) net non-tidal circulation and sediment transport. Together, these processes play a major role in changing the configuration of the estuary and filling it with sediment. The deposits at the mouth of the bay hold keys both to the evolution of the bay during the Holocene transgression and to the history of previous generations of the bay. The deposit associated with the shoals at the mouth of the bay, the bay-mouth sand, is a distinct stratigraphic unit composed mostly of uniform, gray, fine sand. The position and internal structure of the unit shows that it is related to near-present sea level, and thus is less than a few thousand years old. The processes affecting the upper surface of the deposit and the patterns of erosion and deposition at this surface are complex, but the geometry and structure of the deposit indicate that it is a coherent unit that is prograding bayward and tending to fill the estuary. The source of the bay-mouth sand is primarily outside the bay in the nearshore zone of the Delmarva Peninsula and on the inner continental shelf. The internal structure of the deposit, its surface morphology, its heavy-mineral composition, bottom-current studies, comparative bathymetry, and sediment budgets all suggest that sand is brought to the bay mouth by southerly longshore drift along the Delmarva Peninsula and then swept into the bay. In addition to building the southward- and bayward-prograding bay-mouth sand, these processes result in sand deposition tens of kilometers into the bay. ?? 1988.

Thickness of unconsolidated deposits of the Puget Sound aquifer system, Washington and British Columbia

USGS Publications Warehouse

Jones, M.A.

1996-01-01

The Puget-Willamette Lowland is located in western Washington, western Oregon, and a small part of southwestern British Columbia, Canada. The Puget-Willamette Lowland study area is composed of two distinct subareas, the Puget Sound Lowland and the Willamette Lowland. This report presents the results of mapping the thickness of the unconsolidated deposits in the Puget Sound Lowland. The thickness of the unconsolidated deposits ranges from a discontinuous veneer in areas of bedrock outcrop to more than 3,600 feet. Available information shows that the unconsolidated deposits are thickest in the Fraser-Whatcom, Everett, Seattle, and Tacoma Basins. The mapped thickness of the unconsolidated deposits in the Tacoma Basin is probably underestimated because of the scarcity of wells penetrating the full thickness of the unconsolidated deposits and the lack of sufficient marine-seismic data.

The geologic relationships of industrial mineral deposits and asbestos in the western united states

USGS Publications Warehouse

VanGosen, B.S.

2009-01-01

In recent years, U.S. regulatory agencies have placed emphasis on identifying and regulating asbestos dust exposures in the mining environment, with a particular focus upon industrial mineral deposits in which asbestos occurs as an accessory mineral. Because asbestos minerals form in specific geologic environments, only certain predictable types of industrial mineral deposits can potentially host asbestos mineralization. By applying a basic knowledge of asbestos geology, the costly and time consuming efforts of asbestos monitoring and analyses can be directed towards those mineral deposit types most likely to contain asbestos mineralogy, while saving efforts on the mineral deposits that are unlikely to contain asbestos. While the vast majority of industrial mineral deposits in the Western United States are asbestos-free, there are several types that can, in some instances, host asbestos mineralization, or be closely associated with it. These industrial mineral deposits include a few types of aggregate, dimension, and decorative stone, and some deposits of chromite-nickel, magnesite, nepheline syenite, olivine, rare earth elements, talc, vermiculite, and wollastonite.

Evaluating the Contributions of Atmospheric Deposition of Carbon and Other Nutrients to Nitrification in Alpine Environments

NASA Astrophysics Data System (ADS)

Oldani, K. M.; Mladenov, N.; Williams, M. W.

2013-12-01

The Colorado Front Range of the Rocky Mountains contains undeveloped, barren soils, yet in this environment there is strong evidence for a microbial role in increased nitrogen (N) export. Barren soils in alpine environments are severely carbon-limited, which is the main energy source for microbial activity and sustenance of life. It has been shown that atmospheric deposition can contain high amounts of organic carbon (C). Atmospheric pollutants, dust events, and biological aerosols, such as bacteria, may be important contributors to the atmospheric organic C load. In this stage of the research we evaluated seasonal trends in the chemical composition and optical spectroscopic (fluorescence and UV-vis absorbance) signatures of snow, wet deposition, and dry deposition in an alpine environment at Niwot Ridge in the Rocky Mountains of Colorado to obtain a better understanding of the sources and chemical character of atmospheric deposition. Our results reveal a positive trend between dissolved organic carbon concentrations and calcium, nitrate and sulfate concentrations in wet and dry deposition, which may be derived from such sources as dust and urban air pollution. We also observed the presence of seasonally-variable fluorescent components that may be attributed to fluorescent pigments in bacteria. These results are relevant because atmospheric inputs of carbon and other nutrients may influence nitrification in barren, alpine soils and, ultimately, the export of nitrate to alpine watersheds.

Fuel inventory and deposition in castellated structures in JET-ILW

NASA Astrophysics Data System (ADS)

Rubel, M.; Petersson, P.; Zhou, Y.; Coad, J. P.; Lungu, C.; Jepu, I.; Porosnicu, C.; Matveev, D.; Kirschner, A.; Brezinsek, S.; Widdowson, A.; Alves, E.; Contributors, JET

2017-06-01

Since 2011 the JET tokamak has been operated with a metal ITER-like wall (JET-ILW) including castellated beryllium limiters and lamellae-type bulk tungsten tiles in the divertor. This has allowed for a large scale test of castellated plasma-facing components (PFC). Procedures for sectioning the limiters into single blocks of castellation have been developed. This facilitated morphology studies of morphology of surfaces inside the grooves for limiters after experimental campaigns 2011-2012 and 2013-2014. The deposition in the 0.4-0.5 mm wide grooves of the castellation is ‘shallow’. It reaches 1-2 mm into the 12 mm deep gap. Deuterium concentrations are small (mostly below 1  ×  1018 cm-2). The estimated total amount of deuterium in all the castellated limiters does not exceed the inventory of the plasma-facing surfaces (PFS) of the limiters. There are only traces of Ni, Cr and Fe deposited in the castellation gaps. The same applies to the carbon content. Also low deposition of D, Be and C has been measured on the sides of the bulk tungsten lamellae pieces. Modelling clearly reflects: (a) a sharp decrease in the measured deposition profiles and(b) an increase in deposition with the gap width. Both experimental and modelling data give a strong indication and information to ITER that narrow gaps in the castellated PFC are essential. X-ray diffraction on PFS has clearly shown two distinct composition patterns: Be with an admixture of Be-W intermetallic compounds (e.g. Be22W) in the deposition zone, whilst only pure Be has been detected in the erosion zone. The lack of compound formation in the erosion zone indicates that no distinct changes in the thermo-mechanical properties of the Be PFC might be expected.

Lithofacies, Age, and Sequence Stratigraphy of the Carboniferous Lisburne Group in the Skimo Creek Area, Central Brooks Range

USGS Publications Warehouse

Dumoulin, Julie A.; Whalen, Michael T.; Harris, Anita G.

2008-01-01

The Lisburne Group, a mainly Carboniferous carbonate succession that is widely distributed across northern Alaska, contains notable amounts of oil and gas at Prudhoe Bay. Detailed studies of the Lisburne in the Skimo Creek area, central Brooks Range, delineate its lithofacies, age, conodont biofacies, depositional environments, and sequence stratigraphy and provide new data on its hydrocarbon source-rock and reservoir potential, as well as its thermal history, in this area. We have studied the Lisburne Group in two thrust sheets of the Endicott Mountains allochthon, herein called the Skimo and Tiglukpuk thrust sheets. The southern, Skimo Creek section, which is >900 m thick, is composed largely of even-bedded to nodular lime mudstone and wackestone intercalated with intervals of thin- to thick-bedded bioclastic packstone and grainstone. Some parts of the section are partially to completely dolomitized and (or) replaced by chert. A distinctive, 30-m-thick zone of black, organic-rich shale, lime mudstone, and phosphorite is exposed 170 m below the top of the Lisburne. The uppermost 40 m of section is also distinctive and made up of dark shale, lime mudstone, spiculite, and glauconitic grainstone. The northern, Tiglukpuk Creek section, which is similar to the Skimo Creek section but only ~760 m thick, includes more packstone and grainstone and less organic-rich shale. Analyses of conodonts and foraminifers indicate that both sections range in age from late Early Mississippian (Osagean) through Early Pennsylvanian (early Morrowan) and document a hiatus of at least 15 m.y. at the contact between the Lisburne and the overlying Siksikpuk Formation. No evidence of subaerial exposure was observed along this contact, which may represent a submarine erosional surface. Lithofacies and biofacies imply that the Lisburne Group in the study area was deposited mainly in midramp to outer-ramp settings. Deepest water strata are mud rich and formed below storm or fair-weather wave base on the outer ramp to outer midramp; shallowest facies are storm, sand-wave, and shoal deposits of the inner midramp to inner ramp. A relatively diverse, open-marine fauna occurs throughout much of the Lisburne in the study area, but some beds also contain clasts typical of more restricted, shallow-water environments that were likely transported seaward by storms and currents. Radiolarians are abundant in the shale and phosphorite unit at Skimo Creek and also occur in equivalent strata at Tiglukpuk Creek; high gamma-ray response and elevated total organic-carbon contents (max 5?8 weight percent) also characterize this unit at Skimo Creek. Lithologic, faunal, and geochemical data all suggest that these rocks formed mainly in an outer-ramp to basinal setting with low sedimentation rates, high productivity, and poorly oxygenated bottom water. Shale and mudstone at the top of the Lisburne Group accumulated in a similarly sediment starved, mainly outer ramp environment but lack comparable evidence for high nutrient and low oxygen levels during deposition. Vertical shifts in rock types and faunas delineate numerous parasequences and six probable third-order sequences in the study area; the same sequences are also recognized in the Lisburne Group to the east. Transgressive-system tracts in these sequences generally fine upward, whereas highstand-system tracts coarsen upward. Sequences in the Tiglukpuk Creek section are mostly thinner, contain thinner and more numerous parasequences, and accumulated in somewhat shallower settings than those in the Skimo Creek section. These differences reflect the more seaward position and, thus, increased accommodation space of the Skimo Creek section relative to the Tiglukpuk Creek section during deposition. Organic-rich calcareous shale in the shale and phosphorite unit has a cumulative thickness of at least 15 m and a lateral extent of >50 km; this lithology is the best potential hydrocarbon source rock in the Lisburne Group

Seafloor environments within the Boston Harbor- Massachusetts Bay sedimentary system: A regional synthesis

USGS Publications Warehouse

Knebel, H.J.; Circe, R.C.

1995-01-01

Modern seafloor sedimentary environments within the glaciated, topographically complex Boston Harbor and Massachusetts Bay area have been interpreted and mapped from an extensive collection of sidescan sonar records and supplemental marine geologic data. Three categories of environments are present that reflect the dominant long-term processes of erosion or nondeposition, deposition, and sediment reworking. (1) Environments of erosion or nondeposition comprise exposures of bedrock, glacial drift, coarse lag deposits, and possibly coastal plain rocks that contain sediments (where present) ranging from boulder fields to gravelly sands and occur in areas of relatively strong currents. (2) Environments of deposition contain fine-grained sediments ranging from muddy sands to muds that have accumulated in areas of predominantly weak bottom currents. (3) Environments of sediment reworking contain patches with textures ranging from sandy gravels to muds that have been produced by a combination of erosion and deposition in areas with variable bottom currents. The distribution of sedimentary environments across the Boston Harbor-Massachusetts Bay area is extremely patchy. Locally, this patchiness is due either to modifications of bottom-current strength (caused by the irregular topography and differences in water depth) or to small-scale changes in the supply of fine-grained sediments. Regional patchiness, however, reflects differences in geologic and oceanographic conditions among the estuarine, inner shelf, and basinal parts of the sedimentary system. The estuarine part of the system (Boston Harbor) is a depositional trap for fine-grained sediments because it is protected from large waves, has generally weak and variable tidal currents, and receives a large supply of fine grained detritus from natural and anthropogenic sources. The inner shelf, on the other hand, is largely an area of erosion or nondeposition due to sediment removal and redistribution during past sea-level changes, to sediment resuspension and winnowing by modern waves and currents, and to an inadequate supply of fine-grained sediments. The basinal part of the system (Stellwagen Basin) is mainly a tranquil depositional environment in which fine-grained sediments from several potential sources settle through the water column and accumulate under weak bottom currents. This study indicates areas within the Boston Harbor-Massachusetts Bay sedimentary system where fine-grained sediments and associated contaminants are likely to be either moved or deposited. It also provides a guide to the locations and variability of benthic habitats.

Nitrogen mineralization across an atmospheric nitrogen deposition gradient in Southern California deserts

Treesearch

L.E. Rao; D.R. Parker; Andrzej Bytnerowicz; E.B. Allen

2009-01-01

Dry nitrogen deposition is common in arid ecosystems near urban and agricultural centers, yet its impacts on natural environments are relatively understudied. We examined the effects of N deposition on soil N mineralization across a depositional gradient at Joshua Tree National Park. We hypothesized that N deposition affects N mineralization by promoting...

The Early Gulf of Mexico as a Subaerial Basin Below Sea Level (SABSEL) Basin. Evidence from Stratigraphy and Facies of Luanne salt, Norphlet sandstone and Smackover Brown Dense Formations.

NASA Astrophysics Data System (ADS)

Cassidy, M. M.

2016-12-01

Many workers recognize that large salt deposits form in post-rift sag basins which were subaerial and susceptible to rapid flooding from adjacent oceansl. I have termed these basins "subaerial basins below sea level" or "SABSEL" basins. A key marker of SABSEL basins are terrestrial sediments immediately overlain by deepwater sediments with no transition. Desert deposits -including Aeolian dunes- are preserved in the adiabatically heated depression. Dunes are not eroded by transgressing seas but are drowned by rising water as in a bath tub. They maintain their shape. Deepwater marine black shales or limestones drape the dunes. The Southern North sea is an example. Above the original marine shale over the dunes are evaporites. Winds descending into the basin were heated by adiabatic compression providing the very hot air need to allow survival of potassium salts. A similar situation was probably active during the Messinian salinity crisis in the Mediterranean basin, and the opening of the South Atlantic. In the Gulf of Mexico (GOM) a desert is on the Louann salt. Here the sea invaded the lows first to deposit the salt overlying tilted fault blocks of the opening basin, as in the Afar Triangle of Africa. In the GOM entry to the west fed in sea water, then closed. The Norphlet desert formed. Streams carried sands to the basin to be spread by winds where they willed, not limited to sand entry areas. Upon deposition their original weight depressed the salt. Seismic shows depressions in the salt but the dunes are high at the top Norphlet, forming distinctive small "eyes" at the top salt. The 600 foot dunes are draped by deep water dolomitic finely laminated organic rich black/ brown shale, the Brown Dense Facies of the Smackover formation. The lack of reworking of the dunes found by detailed seismic is distinctive of deposition in a SABSEL basin. The overlap of terrestrial sediments by deep water deposition is good evidence of sudden flooding. In summary this vertical succession of facies in the Jurassic can be explained as a SABSEL Basin. Evidence of Norphlet presence exists east of the Mississippi delta and the in Campeche embayment of Mexico. Search for its distinctive seismic signature throughout the Gulf of Mexico should continue, and may yield more large gas deposits.

30 CFR 250.1404 - Which violations will MMS review for potential civil penalties?

Code of Federal Regulations, 2011 CFR

2011-07-01

... civil penalties? 250.1404 Section 250.1404 Mineral Resources BUREAU OF OCEAN ENERGY MANAGEMENT...), property, any mineral deposit, or the marine, coastal, or human environment; or (c) Violations that cause...), property, any mineral deposit, or the marine, coastal, or human environment. (d) Violations of the oil...

Deposition and deformation of stratified rocks in the northern Nia Mensa region of Valles Marineris, Mars

NASA Astrophysics Data System (ADS)

Okubo, C. H.

2016-12-01

Large-scale structural and geologic mapping based on HiRISE (High Resolution Imaging Science Experiment) digital elevation models reveals new details of the depositional environment for the stratified rocks in the northern Nia Mensa region of eastern Candor Chasma, Valles Marineris, Mars. The map area encompasses the contact between massive sedimentary rocks that comprise most of Nia Mensa and the stratified sedimentary and mass-wasting deposits exposed between Nia Mensa and the north wall of eastern Candor Chasma. The area contains a stratified fan-like deposit on the lower slopes of Nia Mensa. The strata within this deposit dip outward at < 10°, away from its morphologic apex, consistent with an origin as a depositional fan (rather than being carved into a fan shape by erosion). Whether this fan has a subaerial or submarine origin has not yet been determined. Additionally, the fan and surrounding stratified rocks exhibit evidence of soft-sediment deformation in the form of clastic dikes and contorted bedding, indicating that these deposits were water-saturated at the time of deformation. Finally, the northern section of the map area encompasses part of a fractured rise, and deposits interpreted as mud flows mantle the top of this rise. Inferred flow directions suggest that the mud erupted out of these fractures. These findings place constraints on the depositional environment of the local stratified bedrock. The presence of the fan deposit indicates that lateral transport was a component in the depositional history of these sediments. Therefore the sediments did not form entirely as a mantling deposit, such as air fall ash or sediments settled out of a water column. The soft-sediment deformation and subsurface mobilized sediments indicate that groundwater was present in the area after emplacement of the stratified deposits, but before its lithification. These findings point to a wet-playa to lacustrine depositional environment.

Organic staining on bone from exposure to wood and other plant materials.

PubMed

Pollock, Corey R; Pokines, James T; Bethard, Jonathan D

2018-02-01

Determining the depositional environment and the postmortem alterations to a set of remains are necessary aspects of a forensic investigation to explain the circumstances surrounding the death of an individual. The present study examines organic staining as a method for reconstructing the depositional environment of skeletal remains and the taphonomic agents with which they came into contact. Organic staining results largely from tannins leaching from plant materials and therefore can be seen on bone deposited in wooden coffin environments or on terrestrial surfaces. The present study examines the hypothesis that the degree of staining observed on skeletal elements would increase as the length of exposure to the organic matter increased and that different plant materials and environments would leave different patterns or colorations of staining. The sample consisted of 165 pig (Sus scrofa) femora divided into four groups exposed to differing experimental conditions, including burial in direct contact with soil or burial in a simulated coffin environment, immersion in water with wood samples, and surface deposition with plant matter contact. The bones were removed once a month from their experimental environments and the level of staining was recorded qualitatively using the Munsell Soil Color Chart. In all of the experimental environments, staining was present after two months of exposure, and the color darkened across the bone surface with each episode of data collection. The results from the present study indicate that staining can manifest on bone within a relatively short time frame once skeletonization occurs and a variety of colorations or patterns of staining can manifest based on the plant material. The present research also demonstrates the potential of organic staining to aid in estimations of the postmortem interval as well as a depositional environmental reconstruction through plant species identification. Copyright © 2017 Elsevier B.V. All rights reserved.

Factors associated with the deposition of Cladophora on Lake Michigan beaches in 2012

USGS Publications Warehouse

Riley, Stephen C.; Tucker, Taaja R.; Adams, Jean V.; Fogarty, Lisa R.; Lafrancois, Brenda Moraska

2015-01-01

Deposition of the macroalgae Cladophora spp. was monitored on 18 beaches around Lake Michigan during 2012 at a high temporal frequency. We observed a high degree of spatial variability in Cladophora deposition among beaches on Lake Michigan, even within local regions, with no clear regional pattern in the intensity of Cladophora deposition. A strong seasonal pattern in Cladophora deposition was observed, with the heaviest deposition occurring during mid-summer. Several beaches exhibited high temporal variability in Cladophora deposition over short time scales, suggesting that drifting algal mats may be extremely dynamic in nearshore environments of the Great Lakes. Cladophora deposition on Lake Michigan beaches was primarily related to the presence of nearshore structures, local population density, and nearshore bathymetry. There was relatively little evidence that waves, winds, or currents were associated with Cladophora deposition on beaches, but this may be due to the relatively poor resolution of existing nearshore hydrodynamic data. Developing a predictive understanding of beach-cast Cladophora dynamics in Great Lakes environments may require both intensive Cladophora monitoring and fine-scale local hydrodynamic modeling efforts.

Sedimentological Characteristics and Classification of Depositional Processes and Deposits in the Glacial Environment,

DTIC Science & Technology

1981-12-01

I characteristics and classification of depositional processes and d,4, r -%sits in the glacial environment C",. 44k (1-I J For conversion of SI metric...Discussion with Dr. John Shaw, Dr. Geoffrey Boulton, Dr. David Croot and Dr. Ross Powell helped considerably in formulating ideas presented in this report...glacial or non- glacial origins of diamictites of Precambrian and COMPARISON OF MELT-OUT other ages (e.g., Schermerhorn 1974, Edwards AND SEDIMENT FLOW

Evolution of Mars' northern polar seasonal CO2 deposits: Variations in surface brightness and bulk density

NASA Astrophysics Data System (ADS)

Mount, Christopher P.; Titus, Timothy N.

2015-07-01

Small-scale variations of seasonal ice are explored at different geomorphic units on the Northern Polar Seasonal Cap (NPSC). We use seasonal rock shadow measurements, combined with visible and thermal observations, to calculate density over time. The coupling of volume density and albedo allows us to determine the microphysical state of the seasonal CO2 ice. We find two distinct end-members across the NPSC: (1) Snow deposits may anneal to form an overlying slab layer that fractures. These low-density deposits maintain relatively constant densities over springtime. (2) Porous slab deposits likely anneal rapidly in early spring and fracture in late spring. These high-density deposits dramatically increase in density over time. The end-members appear to be correlated with latitude.

Evolution of Mars’ Northern Polar Seasonal CO2 deposits: variations in surface brightness and bulk density

USGS Publications Warehouse

Mount, Christopher P.; Titus, Timothy N.

2015-01-01

Small scale variations of seasonal ice are explored at different geomorphic units on the Northern Polar Seasonal Cap (NPSC). We use seasonal rock shadow measurements, combined with visible and thermal observations, to calculate density over time. The coupling of volume density and albedo allows us to determine the microphysical state of the seasonal CO2 ice. We find two distinct endmembers across the NPSC: 1) Snow deposits may anneal to form an overlying slab layer that fractures. These low density deposits maintain relatively constant densities over springtime. 2) Porous slab deposits likely anneal rapidly in early spring and fracture in late spring. These high density deposits dramatically increase in density over time. The endmembers appear to be correlated with latitude.

Ultrastructural histochemical investigations of "dense deposit disease". Pathogenetic approach to a special type of mesangiocapillary glomerulonephritis.

PubMed

Muda, A O; Barsotti, P; Marinozzi, V

1988-01-01

Dense deposit disease is characterized by the presence of intramembranous dense deposits; their constituents are unknown but immunological and biochemical studies have demonstrated that they contain no gamma-globulins or any other plasma protein. In order to clarify the nature of the dense deposits better, we investigated their most distinctive character, (marked electron-density) by means of ultrastructural histochemistry techniques using thin sections from Formaldehyde fixed, OsO4 postfixed and Epon embedded specimens collected for diagnostic electron microscopy. The dense deposits have a higher osmium affinity than the lamina densa of normal basement membranes, and the electron-density is strictly osmium-dependent suggesting the presence of a lipid component. Further data, obtained using an extraction method for lipids, seems to confirm our hypothesis.

Geologic map of the Ute Mountain 7.5' quadrangle, Taos County, New Mexico, and Conejos and Costilla Counties, Colorado

USGS Publications Warehouse

Thompson, Ren A.; Turner, Kenzie J.; Shroba, Ralph R.; Cosca, Michael A.; Ruleman, Chester A.; Lee, John P.; Brandt, Theodore R.

2014-01-01

The Ute Mountain 7.5' quadrangle is located in the south-central part of the San Luis Basin of northern New Mexico, in the Rio Grande del Norte National Monument, and contains deposits that record volcanic, tectonic, and associated alluvial and colluvial processes over the past four million years. Ute Mountain has the distinction of being one of the largest intermediate composition eruptive centers of the Taos Plateau, a largely volcanic tableland occupying the southern portion of the San Luis Basin. Ute Mountain rises to an elevation in excess of 3,000 m, nearly 700 m above the basaltic plateau at its base, and is characterized by three distinct phases of Pliocene eruptive activity recorded in the stratigraphy exposed on the flanks of the mountain and in the Rio Grande gorge. Unconformably overlain by largely flat-lying lava flows of Servilleta Basalt, the area surrounding Ute Mountain records a westward thickening of basin-fill volcanic deposits interstratified in the subsurface with Pliocene basin-fill sedimentary deposits derived from older Tertiary and Precambrian sources to the east. Superimposed on this volcanic stratigraphy are alluvial and colluvial deposits derived from the flanks of Ute Mountain and more distally-derived alluvium from the uplifted Sangre de Cristo Mountains to the east, that record a complex temporal and stratigraphic succession of Quaternary basin deposition and erosion. Pliocene and younger basin deposition was accommodated along predominantly north-trending fault-bounded grabens. These poorly exposed fault scarps cutting lava flows of Ute Mountain volcano. The Servilleta Basalt and younger surficial deposits record largely down-to-east basinward displacement. Faults are identified with varying confidence levels in the map area. Recognizing and mapping faults developed near the surface in young, brittle volcanic rocks is difficult because: (1) they tend to form fractured zones tens of meters wide rather than discrete fault planes, (2) the relative youth of the deposits has resulted in only modest displacements on most faults, and (3) some of the faults may have significant strike-slip components that do not result in large vertical offsets that are readily apparent in offset of sub-horizontal contacts. Those faults characterized as “certain” either have distinct offset of map units or had slip planes that were directly observed in the field. Lineaments defined from magnetic anomalies form an additional constraint on potential fault locations and are indicated as such on the map sheet.

Preliminary tephra-fall records from three lakes in the Anchorage, Alaska area: advances towards a regional tephrochronostratigraphic framework

NASA Astrophysics Data System (ADS)

Wallace, K. L.; Kaufman, D. S.; Schiff, C. J.; Kathan, K.; Werner, A.; Hancock, J.; Hagel, L. A.

2010-12-01

Sediment cores recovered from three kettle lakes, all within 10 km of Anchorage, Alaska contain a record of tephra fall from major eruptive events of Cook Inlet volcanoes during the past 11250 yr. Prominent tephra layers from multiple cores within each lake were first correlated within each basin using physical properties, major-oxide glass geochemistry, and constrained by bracketing radiocarbon age. Distinct tephra from each lake were then correlated among all three lakes using the same criteria to develop a composite tephrostratigraphic framework for the Anchorage area. Lorraine Lake, the northern-most lake contains 17 distinct tephra layers; Goose Lake, the eastern most lake contains 10 distinct tephra layers; and Little Campbell Lake, to the west, contains 7 distinct tephra layers. Thinner, less-prominent tephra layers, reflecting smaller or more distant eruptions, also occur but are not included as part of this study. Of the 33 tephra layers, only two could be confidently correlated among all three lakes, and four other correlative deposits were recognized in two of the three lakes. The minimum number of unique major tephra-fall events in the Anchorage area is 22 in the past 11200 years, or about 1 event every 500 years. This number underestimates the actual number of eruptions because not attempt was made to locate crypto-tephra. All but perhaps one tephra deposit originated from Cook Inlet volcanoes with the most prolific source being Mount Spurr/Crater Peak, which is accountable for at least 8 deposits. Combining radiocarbon ages to produce an independent age model for each lake is in progress and will aid in confirming correlations and assigning detailed modeled-tephra age and uncertainty to each tephra layer.

The Tuscarora Au-Ag district: Eocene volcanic-hosted epithermal deposits in the Carlin gold region, Nevada

USGS Publications Warehouse

Castor, S.B.; Boden, D.R.; Henry, C.D.; Cline, J.S.; Hofstra, A.H.; McIntosh, W.C.; Tosdal, R.M.; Wooden, J.P.

2003-01-01

The Tuscarora mining district contains the oldest and the only productive Eocene epithermal deposits in Nevada. The district is a particularly clear example of association of low-sulfidation deposits with igneous activity and structure, and it is unusual in that it consists of two adjoining but physically and chemically distinct types of low-sulfidation deposits. Moreover, Tuscarora deposits are of interest because they formed contemporaneously with nearby, giant Carlin-type gold deposits. The Tuscarora deposits formed within the 39.9 to 39.3 Ma Tuscarora volcanic field, along and just outside the southeastern margin of the caldera-like Mount Blitzen volcanic center. Both deposit types formed at 39.3 Ma, contemporaneous with the only major intrusive activity in the volcanic field. No deposits are known to have formed during any of the intense volcanic phases of the field. Intrusions were the apparent heat source, and structures related to the Mount Blitzen center were conduits for hydrothermal circulation. The ore-forming fluids interacted dominantly with Eocene igneous rocks. The two deposit types occur in a northern silver-rich zone that is characterized by relatively high Ag/Au ratios (110-150), narrow alteration zones, and quartz and carbonate veins developed mostly in intrusive dacite, and in a southern gold-rich zone that is typified by relatively low Ag/Au ratios (4-14), more widespread alteration, and quartz-fissure and stockwork veins commonly developed in tuffaceous sedimentary rocks. The deposit types have similar fluid inclusion and Pb and S isotope characteristics but different geochemical signatures. Quartz veins from both zones have similar thermal and paragenetic histories and contain fluid inclusions that indicate that fluids cooled from between 260?? and 230??C to less than 200??C. Fluid boiling may have contributed to precious-metal deposition. Veins in both zones have relatively high As and Sb and low Bi, Te, and W. The silver zone has high Ca, Pb, Mn, Zn, Cd, Tl, and Se. The gold zone has high Hg and Mo. A few samples from an area of overlap between the two zones share chemical characteristics of both deposit types. The deposit types could represent a single zoned or evolving system in which hydrothermal fluids rose along structures within the silver zone, preferentially deposited Ag and base metals, and then spread into the gold zone. Alternatively, the deposit types could represent two distinct but temporally indistinguishable hydrothermal cells that only narrowly overlapped spatially. As noted in previous studies, the hydrothermal fluids that generated the Tuscarora and other epithermal deposits could have evolved from Carlin-type fluids by boiling and mixing with meteoric water. If so, the Tuscarora deposit may represent epithermal conditions above Carlin-type deposits, and Carlin-type deposits may lie beneath the district.

Outstanding Universal Values of the Korean Archipelago Getbol: Its potential for World Heritage Nomination

NASA Astrophysics Data System (ADS)

Woo, K. S.; Chun, S. S.; Moon, K. O.

2017-12-01

The `Korean Archipelago Getbol (KAG; Getbol means tidal flat deposits in Korean)' has developed due to the decreasing accommodation space during the Holocene sea-level rise on the broad epicontinental shelf of the southeastern part of the Yellow Sea. Sedimentation and evolution show a variety of quite distinctive tidal flat patterns with intertidal and subtidal drainage systems depending upon the location and orientation of rocky shores. The following KAG`s Outstanding Universal Values are suggested to support the WH: 1) It is the unique coastal sedimentary environment formed by special geological and oceanographic setting in the world. It is the only place in the world where tide-controlled sedimentation processes have produced special tidal flats surrounding numerous rocky islands on a broad epicontinental shelf near convergent tectonic boundary. Macrotidal currents combined with waves and typhoons in this semi-closed oceanographic setting have provided unique geological and oceanographic conditions for their formation. 2) It diplays the most dynamic and complicated, but stable coastal depositional system in the world. Even though the property has been constantly influenced by strong microtidal currents combined with East Asian Monsoon climate (winter erosion and summer deposition) with occasional typhoons during summer, Getbol has maintained its stable depositional system and tidal flat sediments have been accumulated for the past 9,000 years. Sufficient supply of suspended load through Geumgang River provides sustainable depositional system within the property. Complicated island-topography also produced the most complicated and divese depositional systems as well as the deepest tidal channels in the world. (3) The KAG shows the thickest tidal flat sediments protected by numerous islands. Aggradation of tidal sediments has caught up with the rapid Holocene sealevel rise and produced the thickest tidal flat sediments in the world. As a results, numerous former islands of relatively elevated areas have been vanished and hidden. In addition, the KAG shows a complete story of geological, ecological and conservational integrity (the wholeness and intactness). Thus, we strongly believe that the KAG has great potential to be inscribed on a World Heritage List for the criterion (viii).

Bouse Formation in the Bristol basin near Amboy, California, USA

USGS Publications Warehouse

Miller, David M.; Reynolds, Robert E.; Bright, Jordan E.; Starratt, Scott W.

2014-01-01

Limestone beds underlain and overlain by alluvial fan conglomerate near Amboy, California, are very similar in many respects to parts of the Bouse Formation, suggesting that an arm of the Pliocene Bouse water body extended across a wide part of the southern Mojave Desert. The deposits are north of the town of Amboy at and below an elevation of 290 m, along the northern piedmont of the Bristol “dry” Lake basin. The Amboy outcrops contain the Lawlor Tuff (4.83 Ma), which is also found in an outcrop of the Bouse Formation in the Blythe basin near Buzzards Peak in the Chocolate Mountains, 180 km southeast of Amboy. Bouse exposures near Amboy are ∼3.4 m thick, white, distinctly bedded, with limestone and calcareous sandstone as well as stromatolite mounds; we interpret these as nearshore deposits. The Bouse at Amboy contains ostracodes, diatoms, and mollusks that indicate saline lake or estuarine environments with an admixture of fresh-water forms. Along with wading bird tracks and a spine from a marine fish, these fossils suggest that the deposits formed in saline waters near a fresh-water source such as a perennial stream. Beds of the outcrop dip southward and are 113 m above the surface of Bristol Playa, where similar age sediments are buried 270+ m deep, indicating significant faulting and vertical tectonics in this part of the Eastern California Shear Zone during the past 5 m.y. Confirmation of the Bouse Formation at Amboy strengthens previous assignments to the Bouse Formation for mudstones in driller logs at Danby “dry” Lake, California, and suggests that areally extensive arms of the Bouse water body were west of the Blythe basin. The Bristol basin arm of the lower Bouse basin probably was restricted from the main water body by narrow passages, but Bouse sediment there is similar to that in the Blythe basin, suggesting generally similar water chemistry and environmental conditions. Examining the degree to which Bouse deposits in the western arms differed from Bouse deposits in the Blythe basin offers an approach to test whether the southernmost Bouse water body was deposited in an estuarine or lacustrine setting.

Sedimentology of latero-frontal moraines and fans on the west coast of South Island, New Zealand

NASA Astrophysics Data System (ADS)

Evans, David J. A.; Shulmeister, James; Hyatt, Olivia

2010-12-01

Exposures through the LGM latero-frontal moraine loops at sites along the west coast of South Island, New Zealand reveal a depositional environment that was dominated by the progradation of steep fronted, debris flow-fed fans, manifest in crudely stratified to massive diamictons, arranged in sub-horizontal to steeply dipping clinoforms and containing discontinuous bodies of variably sorted, stratified sediment (LFA 1). The fans were constructed by debris-covered glaciers advancing over outwash plains, as recorded by well stratified and horizontally bedded gravels, sands and diamicts (LFA 0). The ice-contact slopes of the fans are offlapped by retreat phase deposits in the form of glacilacustrine depo-centres (LFA 2), which record the existence of moraine-dammed lakes. Interdigitation of lake rhythmites and subaerial to subaqueous sediment gravity flow deposits documents intense debris-flow activity on unstable moraine/fan surfaces. Glacier readvances in all catchments are documented by glacitectonic disturbance and localized hydrofracturing of LFA 2, followed by the emplacement of schist-dominated debris flow-fed fans (LFA 3) inside and over the top of the earlier latero-frontal moraine/fan loops. Contorted and disturbed bedding in LFA 3 reflects its partial deposition in supraglacial positions. Clast lithologies in LFAs 1 and 3 reveal that two distinct transport pathways operated during moraine construction, with an early period of latero-frontal fan construction involving mixed lithologies and a later period of ice-contact/supraglacial fan construction dominated by schist lithologies from the mountains. These two periods of deposition were separated by a period of moraine abandonment and paraglacial reworking of ice-contact slopes to produce LFA 2. The occurrence of LFA 3 at all sites indicates that the glacier readvance phase responsible for its deposition was not localized or glacier-specific, and involved the transfer of large volumes of schist, possibly due to rock slope failures, onto glacier surfaces. The absence of any sediment that could be unequivocally classified as subglacial till reflects the dominance of debris flow and glacifluvial processes in latero-frontal moraine construction in this hyper-humid west coast setting.

Upper Cenozoic sediments of the lower Delaware Valley and the northern Delmarva Peninsula, New Jersey, Pennsylvania, Delaware, and Maryland

USGS Publications Warehouse

Owens, James Patrick; Minard, James Pierson

1979-01-01

The 'yellow gravels' referred to by R. D. Salisbury in 1898 and the 'Trenton gravel,' as defined by H. C. Lewis in 1880, were investigated along the inner edge of the New Jersey Coastal Plain in southern New Jersey and in the northern Delmarva Peninsula. The highest level deposits, the Beacon Hill gravel, are found on only the highest hills in the New Jersey Coastal Plain. Their distribution suggests deposition from north to south across the plain. After deposition of the Beacon Hill, probably in middle or late Miocene time, a narrow valley was formed paralleling the inner edge of the New Jersey Coastal Plain between Raritan Bay and Camden. South of Camden, the valley broadened, covering much of southern New Jersey. The deposits in this valley are largely the Bridgeton Formation as we have redefined it. A second narrow valley was entrenched through the Bridgeton between Trenton and Salem, N.J. This valley broadens and covers much of the northern Delmarva Peninsula west of the Delaware River. The fill in the valley is largely the Pensauken Formation, as we have redefined it in our report. Collectively, the Beacon Hill, the Bridgeton, and the Pensauken were originally the 'yellow gravels' of Salisbury. These deposits are all fluviatile in origin and were largely formed as a series of step like downcutting channels. The Delaware Valley between Trenton and the lower Delaware Bay region is occupied by the 'Trenton gravel,' which is below the average level of the 'yellow gravels.' Two units recognized throughout the area and informally named the Spring Lake beds and the Van Sciver Lake beds are lithologically distinct from the 'yellow gravel' formations. The lithologies of the Spring Lake beds and the Van Sciver Lake beds are much more heterogeneous than those of the older formations. These two units, particularly, contain much greater amounts of silt and clay, often in thick beds. The depositional environments associated with the two units include fluviatile, estuarine, and marginal marine. Both these units are interpreted to be late Pleistocene (Sangamonian) in age.

Petrologic, tectonic, and metallogenic evolution of the southern segment of the ancestral Cascades magmatic arc, California and Nevada

USGS Publications Warehouse

du Bray, Edward A.; John, David A.; Cousens, Brian L.

2013-01-01

Although rocks in the two arc segments have similar metal abundances, they are metallogenically distinct. Small porphyry copper deposits are characteristic of the northern segment whereas significant epithermal precious metal deposits are most commonly associated with the southern segment. These metallogenic differences are also fundamentally linked to the tectonic settings and crustal regimes within which these two arc segments evolved.

Accumulation of sphingolipid activator proteins (SAPs) A and D in granular osmiophilic deposits in miniature Schnauzer dogs with ceroid-lipofuscinosis.

PubMed

Palmer, D N; Tyynelä, J; van Mil, H C; Westlake, V J; Jolly, R D

1997-03-01

The neuronal ceroid-lipofuscinoses (NCL, Batten disease) are fatal inherited neurodegenerative diseases of children characterized by retinal and brain atrophy and the accumulation of electron-dense storage bodies in cells. Mutations in different genes underlie different major forms. The infantile disease (CLN-1, McKusick 256730) is distinguished by the storage of the sphingolipid activator proteins (SAPs) A and D in distinctive granular osmiophilic deposits (GRODs). This contrasts with the other major forms, where subunit c of mitochondrial ATP synthase is stored in various multilamellar profiles. Ceroid-lipofuscinoses also occur in dogs, including a form in miniature Schnauzers with distinctive granular osmiophilic deposit-like storage bodies. Antisera to SAPs A and D reacted to these storage bodies in situ. The presence of SAP D was confirmed by Western blotting and of SAP A by protein sequencing. Neither subunit c of mitochondrial ATP synthase nor of vacuolar ATPase is stored. This suggests that there are two families of ceroid-lipofuscinoses, the subunit c-storing forms, and those in which SAPs A and D, and perhaps other proteins, accumulate. Further work is required to determine whether other forms with granular osmiophilic deposits belong to the latter class and the genetic relationships between them and the human infantile disease.

Morphological, Structural and Optical Evolution of Ag Nanostructures on c-Plane GaN Through the Variation of Deposition Amount and Temperature

NASA Astrophysics Data System (ADS)

Sui, Mao; Li, Ming-Yu; Pandey, Puran; Zhang, Quanzhen; Kunwar, Sundar; Lee, Jihoon

2018-03-01

Owing to their tunable properties, Ag nanostructures have been widely adapted in various applications and the morphological control can determine their performance and effectiveness. In this work, we demonstrate the morphological and optical evolution of Ag nanostructures on GaN (0001) by the systematic control of deposition amount at two distinctive annealing temperatures. Based on the Volmer-Weber and coalescence growth models, the nanostructure growth commenced by the thermal solid-state-dewetting evolve in terms of size, density and configuration. At 450 °C, the round-dome shaped Ag nanoparticles (regime I), irregular Ag nano-mounds (regime II) and void-layer structures (regime III) are observed along with the gradually increased deposition amount. As a sharp distinction, the solid state dewetting process occur more radically at 700 °C and also, the Ag sublimation and the effect on the nanostructure formation are observed in a clear regime shift scaled by the deposition amount. Meanwhile, a strong dependency of reflectance spectra evolution on the Ag nanostructure morphology is witnessed for both sets. In particular, Ag dipolar resonance peaks are significantly red-shifted from VIS to NIR regions along with the nanostructure evolution. The reflectance, PL and Raman intensity variation are also observed and discussed based on the evolution of Ag nanostructures.

Recycling and Resistance of Petrogenic Particulate Organic Carbon: Implications from A Chemical Oxidation Method

NASA Astrophysics Data System (ADS)

Zhang, T.; Li, G.; Ji, J.

2013-12-01

Petrogenic particulate organic carbon (OCpetro) represents a small fraction of photosynthetic carbon which escapes pedogenic-petrogenic degradation and gets trapped in the lithosphere. Exhumation and recycling of OCpetro are of significant importance in the global carbon cycle because OCpetro oxidation represents a substantial carbon source to the atmosphere while the re-burial of OCpetro in sediment deposits has no net effect. Though studies have investigated various behaviors of OCpetro in the surface environments (e.g., riverine mobilization, marine deposition, and microbial remineralization), less attention has been paid to the reaction kinetics and structural transformations during OCpetro oxidation. Here we assess the OCpetro-oxidation process based on a chemical oxidation method adopted from soil studies. The employed chemical oxidation method is considered an effective simulation of natural oxidation in highly oxidative environments, and has been widely used in soil studies to isolate the inert soil carbon pool. We applied this chemical method to the OCpetro-enriched black shale samples from the middle-lower Yangtze (Changjiang) basin, China, and performed comprehensive instrumental analyses (element analysis, Fourier transform infrared (FTIR) spectrum, and Raman spectrum). We also conducted step-oxidizing experiments following fixed time series and monitored the reaction process in rigorously controlled lab conditions. In this work, we present our experiment results and discuss the implications for the recycling and properties of OCpetro. Particulate organic carbon concentration of black shale samples before and after oxidation helps to quantify the oxidability of OCpetro and constrain the preservation efficiency of OCpetro during fluvial erosion over large river basin scales. FTIR and Raman analyses reveal clear structural variations on atomic and molecular levels. Results from the step-oxidizing experiments provide detailed information about the reaction kinetics and allow differentiation of different components in OCpetro characterized by distinct reaction rates. All these results lead to a better understanding of OCpetro recycling in the surface environments, and furthermore, the role of OCpetro in the global carbon cycle.

Intercalated europium metal in epitaxial graphene on SiC

DOE PAGES

Anderson, Nathaniel; Hupalo, Myron; Keavney, David; ...

2017-10-25

X-ray magnetic circular dichroism (XMCD) reveals the magnetic properties of intercalated europium metal under graphene on SiC(0001). Intercalation of Eu nanoclusters (average size 2.5 nm) between graphene and SiC substate are formed by deposition of Eu on epitaxially grown graphene that is subsequently annealed at various temperatures while keeping the integrity of the graphene layer. Using sum-rules analysis of the XMCD of Eu M 4,5 edges at T = 15 K, our samples show paramagnetic-like behavior with distinct anomaly at T ≈ 90 K, which may be related to the Nèel transition, T N = 91 K, of bulk metalmore » Eu. Here, we find no evidence of ferromagnetism due to EuO or antiferromagnetism due to Eu 2 O 3, indicating that the graphene layer protects the intercalated metallic Eu against oxidation over months of exposure to atmospheric environment.« less

Mitochondrial lipids in neurodegeneration.

PubMed

Aufschnaiter, Andreas; Kohler, Verena; Diessl, Jutta; Peselj, Carlotta; Carmona-Gutierrez, Didac; Keller, Walter; Büttner, Sabrina

2017-01-01

Mitochondrial dysfunction is a common feature of many neurodegenerative diseases, including proteinopathies such as Alzheimer's or Parkinson's disease, which are characterized by the deposition of aggregated proteins in the form of insoluble fibrils or plaques. The distinct molecular processes that eventually result in mitochondrial dysfunction during neurodegeneration are well studied but still not fully understood. However, defects in mitochondrial fission and fusion, mitophagy, oxidative phosphorylation and mitochondrial bioenergetics have been linked to cellular demise. These processes are influenced by the lipid environment within mitochondrial membranes as, besides membrane structure and curvature, recruitment and activity of different proteins also largely depend on the respective lipid composition. Hence, the interaction of neurotoxic proteins with certain lipids and the modification of lipid composition in different cell compartments, in particular mitochondria, decisively impact cell death associated with neurodegeneration. Here, we discuss the relevance of mitochondrial lipids in the pathological alterations that result in neuronal demise, focussing on proteinopathies.

Femtosecond laser patterning, synthesis, defect formation, and structural modification of atomic layered materials

DOE PAGES

Yoo, Jae-Hyuck; Kim, Eunpa; Hwang, David J.

2016-12-06

This article summarizes recent research on laser-based processing of twodimensional (2D) atomic layered materials, including graphene and transition metal dichalcogenides (TMDCs). Ultrafast lasers offer unique processing routes that take advantage of distinct interaction mechanisms with 2D materials to enable extremely localized energy deposition. Experiments have shown that ablative direct patterning of graphene by ultrafast lasers can achieve resolutions of tens of nanometers, as well as single-step pattern transfer. Ultrafast lasers also induce non-thermal excitation mechanisms that are useful for the thinning of TMDCs to tune the 2D material bandgap. Laser-assisted site-specific doping was recently demonstrated where ultrafast laser radiation undermore » ambient air environment could be used for the direct writing of high-quality graphene patterns on insulating substrates. This article concludes with an outlook towards developing further advanced laser processing with scalability, in situ monitoring strategies and potential applications.« less

Circum-Arctic petroleum systems identified using decision-tree chemometrics

USGS Publications Warehouse

Peters, K.E.; Ramos, L.S.; Zumberge, J.E.; Valin, Z.C.; Scotese, C.R.; Gautier, D.L.

2007-01-01

Source- and age-related biomarker and isotopic data were measured for more than 1000 crude oil samples from wells and seeps collected above approximately 55??N latitude. A unique, multitiered chemometric (multivariate statistical) decision tree was created that allowed automated classification of 31 genetically distinct circumArctic oil families based on a training set of 622 oil samples. The method, which we call decision-tree chemometrics, uses principal components analysis and multiple tiers of K-nearest neighbor and SIMCA (soft independent modeling of class analogy) models to classify and assign confidence limits for newly acquired oil samples and source rock extracts. Geochemical data for each oil sample were also used to infer the age, lithology, organic matter input, depositional environment, and identity of its source rock. These results demonstrate the value of large petroleum databases where all samples were analyzed using the same procedures and instrumentation. Copyright ?? 2007. The American Association of Petroleum Geologists. All rights reserved.

Intercalated europium metal in epitaxial graphene on SiC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anderson, Nathaniel; Hupalo, Myron; Keavney, David

X-ray magnetic circular dichroism (XMCD) reveals the magnetic properties of intercalated europium metal under graphene on SiC(0001). Intercalation of Eu nanoclusters (average size 2.5 nm) between graphene and SiC substate are formed by deposition of Eu on epitaxially grown graphene that is subsequently annealed at various temperatures while keeping the integrity of the graphene layer. Using sum-rules analysis of the XMCD of Eu M 4,5 edges at T = 15 K, our samples show paramagnetic-like behavior with distinct anomaly at T ≈ 90 K, which may be related to the Nèel transition, T N = 91 K, of bulk metalmore » Eu. Here, we find no evidence of ferromagnetism due to EuO or antiferromagnetism due to Eu 2 O 3, indicating that the graphene layer protects the intercalated metallic Eu against oxidation over months of exposure to atmospheric environment.« less

The influence of environmental factors on the deposition velocity of thoron progeny.

PubMed

Li, H; Zhang, L; Guo, Q

2012-11-01

Passive measuring devices are comprehensively employed in thoron progeny surveys, while the deposition velocity of thoron progeny is the most critical parameter, which varies in different environments. In this study, to analyse the influence of environmental factors on thoron progeny deposition velocity, an improved model was proposed on the basis of Lai's aerosol deposition model and the Jacobi's model, and a series of measurements were carried out to verify the model. According to the calculations, deposition velocity decreases with increasing aerosol diameter and also aerosol concentration, while increases with increasing ventilation rate. In typical indoor environments, a typical value of 1.26 × 10(-5)m s(-1) is recommended, with a range between 7.6 × 10(-7) and 3.2 × 10(-4) m s(-1).

Using the geologic setting of talc deposits as an indicator of amphibole asbestos content

USGS Publications Warehouse

Van Gosen, B. S.; Lowers, H.A.; Sutley, S.J.; Gent, C.A.

2004-01-01

This study examined commercial talc deposits in the U.S. and their amphibole-asbestos content. The study found that the talc-forming environment directly influenced the amphibole and amphibole-asbestos content of the talc deposit. Large talc districts in the U.S. have mined hydrothermal talcs that replaced dolostone. Hydrothermal talcs, created by siliceous fluids heated by magmas at depth, consistently lack amphiboles as accessory minerals. In contrast, mineable talc deposits that formed by contact or regional metamorphism consistently contain amphiboles, locally as asbestiform varieties. Examples of contact metamorphic deposits occur in Death Valley, California; these talc-tremolite deposits contain accessory amphibole-asbestos. Talc bodies formed by regional metamorphism always contain amphiboles, which display a variety of compositions and habits, including asbestiform. Some industrial mineral deposits are under scrutiny as potential sources of accessory asbestos minerals. Recognizing consistent relations between the talc-forming environment and amphibole-asbestos content may be used in prioritizing remediation or monitoring of abandoned and active talc mines.

Stratigraphy of the layered terrain in Valles Marineris, Mars

NASA Technical Reports Server (NTRS)

Komatsu, G.; Strom, Roger G.

1991-01-01

The layered terrain in Valles Marineris provides information about its origin and the geologic history of this canyon system. Whether the terrain is sedimentary material deposited in a dry or lacustrine environment, or volcanic material related to the tectonics of the canyon is still controversial. However, recent studies of Gangis Layered Terrain suggests a cyclic sequence of deposition and erosion under episodic lacustrine conditions. The stratigraphic studies are extended to four other occurrences of layered terrains in Valles Marineris in an attempt to correlate and distinguish between depositional environments. The Juvantae Chasma, Hebes Chasma, Ophir and Candor Chasmata, Melas Chasma, and Gangis Layered Terrain were examined. Although there are broad similarities among the layered terrains, no two deposits are exactly alike. This suggests that there was no synchronized regional depositional processes to form all the layered deposits. However, the similar erosional style of the lower massive weakly bedded unit in Hebes, Gangis, and Ophir-Candor suggests it may have been deposited under similar circumstances.

Link between Neogene and modern sedimentary environments in the Zagros foreland basin

NASA Astrophysics Data System (ADS)

Pirouz, Mortaza; Simpson, Guy; Bahroudi, Abbas

2010-05-01

The Zagros mountain belt, with a length of 1800 km, is located in the south of Iran and was produced by collision between the Arabian plate and the Iran micro plate some time in the early Tertiary. After collision, the Zagros carbonate-dominated sedimentary basin has been replaced by a largely clastic system. The Neogene Zagros foreland basin comprises four main depositional environments which reflect the progressive southward migration of the deformation front with time. The oldest unit - the Gachsaran formation - is clastic in the northern part of the basin, but is dominated by evaporates in southern part, being deposited in a supratidal Sabkha-type environment. Overlying the Gachsaran is the Mishan formation, which is characterized by the Guri limestone member at the base, overlain by marine green marls. The thickness of the Guri member increases dramatically towards the southeast. The next youngest unit is the Aghajari Formation which consists of well sorted lenticular sandstone bodies in a red silty-mudstone. This formation is interpreted as representing the floodplain of dominantly meandering rivers. Finally, the Bakhtiari formation consists of mainly coarse-grained gravel sheets which are interpreted to represent braided river deposits. Each of these Neogene depositional environments has a modern day equivalent. For example, the braided rivers presently active in the Zagros mountains are modern analogues of the Bakhtiari. In the downstream direction, these braided rivers become meandering systems, which are equivalents of the Aghajari. Eventually, the meandering rivers meet the Persian gulf which is the site of the ‘modern day' Mishan shallow marine marls. Finally, the modern carbonate system on the southern margin of Persian Gulf represents the Guri member paleo-environment, behind which Sabkha-type deposits similar to the Gachsaran are presently being deposited. One important implication of this link between the Neogene foreland basin deposits and the modern environments is that all formation boundaries are strongly diachronous. Thus, for example, although the Mishan is Burdigalian-Messinian in regions where it is currently undergoing subaerial erosion in the Fars zone, it is presumably still forming today in the modern Persian gulf foredeep.

Reconstructing the Holocene depositional environments along the northern coast of Sfax (Tunisia): Mineralogical and sedimentological approaches

NASA Astrophysics Data System (ADS)

Lamourou, Ali; Touir, Jamel; Fagel, Nathalie

2017-05-01

A sedimentological and mineralogical study of sedimentary cores allowed reconstructing the evolution of depositional environments along the Northern coast of Sfax (Tunisia). The aim of this research work is to identify the factors controlling the sedimentation from the Holocene to the Present time. Three 30-m sediment cores collected by drilling at 30 m water depth were analyzed for their color, magnetic susceptibility signal, grain size by laser diffraction, organic matter content by loss of ignition, carbonate content by calcimetry and mineralogy by X-ray diffraction on bulk powder and clay <2 μm. They broadly present the same sedimentological and mineralogical features. Microscopical observations of petrographic slides allowed identifying six main sedimentary facies. Bulk mineralogical assemblages comprised clay minerals, quartz, calcite, gypsum and K-feldspars were examined. Considerable change was observed in the carbonate content that mimicked the bioclaste abundance and diluted the detrital minerals (clay minerals, quartz and feldspars). The gypsum mainly occurred in the lower sedimentary columns (SC12 and SC9) and in the upper/middle of core SC6. The clay fraction was made of a mixture of kaolinite, illite, smectite and palygorskite with no clear variation through core depth. Both grain-size parameters and magnetic susceptibility profile showed a sharp transition in the upper 2-5 m of the sedimentological columns. Coarse, sandy to gravely sediments characterized by a low magnetic susceptibility signal were replaced by fine bioclastic-rich clayey sediments. The analysis of vertical succession of depositional facies revealed a fluvial depositional environment (coastal plain) basically marked by fluvial channels and inundation plains at the bottom of all cores. However, core-top sediments recorded a littoral marine environment with sand depositions rich in gastropods, lamellibranches and algæ. Depositional facies, sedimentological and mineralogical parameters were consistent with a transition from a fluviatile depositional environment with some emersion phases marked by the gypsum precipitation, to a marine littoral environment. Such evolution was accompanied with a relative sea-level rise which flooded the fluvial system at the coastal plain during the Holocene, in agreement with sea-level fluctuations in southeast Tunisia during the Holocene.

Changes of chromium concentration in alluvial sediments of the Obra river valley

NASA Astrophysics Data System (ADS)

Młynarczyk, Z.; Sobczyński, T.; Słowik, M.

2006-06-01

In this research work, changes in concentration of the chosen chemical element in alluvial sediments have been used to estimate the relative age of floodplain deposits. The research concerning changes of chromium concentration in alluvial deposits was done in the Obra river valley near Międzyrzecz (Western Poland). Chromium was chosen because of its low ability to migrate in groundwater environment. Moreover, this chemical element was used in the process of dyeing textures in Międzyrzecz between the sixteenth and the nineteenth century. Confrontation of changes in chromium concentration and age of alluvial sediments (age estimated in years BP using radiocarbon method) have shown that the sediments with higher chromium contents are much older than the period of development of the weaving industry in Międzyrzecz. Therefore, it is not possible to use changes in chromium concentration to estimate relative age of floodplain sediments. Despite information in the literature about low migration ability of this chemical component (Macioszczyk and Dobrzyński in Hydrogeochemia: strefy aktywnej wymiany wód podziemnych. PWN, Warszawa, 2002; Ball and Izbicki in Appl Geochem 19:1123 1135, 2004) migration of chromium is so intensive that distinct changes in its concentration are observed even before the period of increased human activity.

Uranium (U)-Tolerant Bacterial Diversity from U Ore Deposit of Domiasiat in North-East India and Its Prospective Utilisation in Bioremediation

PubMed Central

Kumar, Rakshak; Nongkhlaw, Macmillan; Acharya, Celin; Joshi, Santa Ram

2013-01-01

Uranium (U)-tolerant aerobic chemo-heterotrophic bacteria were isolated from the sub-surface soils of U-rich deposits in Domiasiat, North East India. The bacterial community explored at molecular level by amplified ribosomal DNA restriction analysis (ARDRA) resulted in 51 distinct phylotypes. Bacterial community assemblages at the U mining site with the concentration of U ranging from 20 to 100 ppm, were found to be most diverse. Representative bacteria analysed by 16S rRNA gene sequencing were affiliated to Firmicutes (51%), Gammaproteobacteria (26%), Actinobacteria (11%), Bacteroidetes (10%) and Betaproteobacteria (2%). Representative strains removed more than 90% and 53% of U from 100 μM and 2 mM uranyl nitrate solutions, respectively, at pH 3.5 within 10 min of exposure and the activity was retained until 24 h. Overall, 76% of characterized isolates possessed phosphatase enzyme and 53% had PIB-type ATPase genes. This study generated baseline information on the diverse indigenous U-tolerant bacteria which could serve as an indicator to estimate the environmental impact expected to be caused by mining in the future. Also, these natural isolates efficient in uranium binding and harbouring phosphatase enzyme and metal-transporting genes could possibly play a vital role in the bioremediation of metal-/radionuclide-contaminated environments. PMID:23080407

Quaternary geology of Alameda County, and parts of Contra Costa, Santa Clara, San Mateo, San Francisco, Stanislaus, and San Joaquin counties, California: a digital database

USGS Publications Warehouse

Helley, E.J.; Graymer, R.W.

1997-01-01

Alameda County is located at the northern end of the Diablo Range of Central California. It is bounded on the north by the south flank of Mount Diablo, one of the highest peaks in the Bay Area, reaching an elevation of 1173 meters (3,849 ft). San Francisco Bay forms the western boundary, the San Joaquin Valley borders it on the east and an arbitrary line from the Bay into the Diablo Range forms the southern boundary. Alameda is one of the nine Bay Area counties tributary to San Francisco Bay. Most of the country is mountainous with steep rugged topography. Alameda County is covered by twenty-eight 7.5' topographic Quadrangles which are shown on the index map. The Quaternary deposits in Alameda County comprise three distinct depositional environments. One, forming a transgressive sequence of alluvial fan and fan-delta facies, is mapped in the western one-third of the county. The second, forming only alluvial fan facies, is mapped in the Livermore Valley and San Joaquin Valley in the eastern part of the county. The third, forming a combination of Eolian dune and estuarine facies, is restricted to the Alameda Island area in the northwestern corner of the county.

Controls on methane concentrations and fluxes in streams draining human-dominated landscapes

USGS Publications Warehouse

Crawford, John T.; Stanley, Emily H.

2016-01-01

Streams and rivers are active processors of carbon, leading to significant emissions of CO2 and possibly CH4 to the atmosphere. Patterns and controls of CH4 in fluvial ecosystems remain relatively poorly understood. Furthermore, little is known regarding how major human impacts to fluvial ecosystems may be transforming their role as CH4 producers and emitters. Here, we examine the consequences of two distinct ecosystem changes as a result of human land use: increased nutrient loading (primarily as nitrate), and increased sediment loading and deposition of fine particles in the benthic zone. We did not find support for the hypothesis that enhanced nitrate loading down-regulates methane production via thermodynamic or toxic effects. We did find strong evidence that increased sedimentation and enhanced organic matter content of the benthos lead to greater methane production (diffusive + ebullitive flux) relative to pristine fluvial systems in northern Wisconsin (upper Midwest, USA). Overall, streams in a human-dominated landscape of southern Wisconsin were major regional sources of CH4 to the atmosphere, equivalent to ~20% of dairy cattle emissions, or ~50% of a landfill’s annual emissions. We suggest that restoration of the benthic environment (reduced fine deposits) could lead to reduced CH4 emissions, while decreasing nutrient loading is likely to have limited impacts to this ecosystem process.

Changes in floral composition with depositional environment in Texas Eocene Manning Formation lignites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gennett, J.A.; Raymond, A.L.

1986-09-01

The floral composition of palynomorph assemblages of Jacksonian Texas lignites is closely linked to depositional systems. Localities on the eastern Gulf coastal plain are included in the late Eocene Fayette delta system, and lignite formation is considered to have occurred in lower deltaic environments. Samples are commonly dominated by grains of Caprifoliipites/Salixpollenites, Momites, or Nyssa, indicating dicotyledonous tree-dominated swamps. Some samples contain abundant Cicatricosspories spores, suggesting marshy, fern-dominated areas. The San Miguel lignite deposit in McMullen County is located on the eastern margin of the south Texas strand-plain/barrier-bar system. Caprifoliipites/Salixpollenites pollen is rare in the San Miguel, and most ofmore » the levels are dominated by small tricolporates such as cupuliferoipollenites and Sapotaceae. Nyssa is locally important. The lignite is considered to have been deposited in a nondeltaic freshwater swamp behind a barrier island. The Miguel Alleman deposit, across the Mexican border in Tamaulipas, is thought to have developed in a lagoonal-estuarine environment. Dinoflagellates such as Wetzeliella are common at some levels, indicating marine conditions. As with San Miguel, small tricolporates and Momipites are common. These assemblages contrast with Sabinian floras. Wilcox Group east Texas lignites were formed in fluvial environments. Betulaceous pollen is common in these coals. Sabinian south Texas lignites formed in marine environments yield dinoflagellates and Chenopodium-type pollen. Chenopods are common in present-day Gulf Coast salt marshes but seem to have been absent from Jackson-age seacoasts.« less

Near-failure detonation behavior of vapor-deposited hexanitrostilbene (HNS) films

NASA Astrophysics Data System (ADS)

Knepper, Robert; Wixom, Ryan R.; Marquez, Michael P.; Tappan, Alexander S.

2017-01-01

Hexanitrostilbene (HNS) films were deposited onto polycarbonate substrates using vacuum thermal sublimation. The deposition conditions were varied in order to alter porosity in the films, and the resulting microstructures were quantified by analyzing ion-polished cross-sections using scanning electron microscopy. The effects of these changes in microstructure on detonation velocity and the critical thickness needed to sustain detonation were determined. The polycarbonate substrates also acted as recording plates for detonation experiments, and films near the critical thickness displayed distinct patterns in the dent tracks that indicate instabilities in the detonation front when approaching failure conditions.

Sedimentology, stratigraphy, and depositional environment of the Crystal Geyser Dinosaur Quarry, east-central Utah

USGS Publications Warehouse

Suarez, M.B.; Suarez, C.A.; Kirkland, J.I.; Gonzalez, Luis A.; Grandstaff, D.E.; Terry, D.O.

2007-01-01

The Crystal Geyser Dinosaur Quarry, near Green River, Utah, is located at the base of the Lower Cretaceous (Barremian) Yellow Cat Member of the Cedar Mountain Formation. The quarry preserves a nearly monospecific accumulation of a new basal therizinosauroid, Falcarius utahensis. We used field descriptions and petrographic analysis to determine the depositional environment and development of the quarry strata. Results of these analyses suggest that the quarry represents multiple episodes of bone accumulation buried by spring and overbank flood deposits. Evidence for these previously undescribed spring deposits includes calcite macroscopic structures within the quarry strata - such as pisolites and travertine fragments - and calcite micromorphologies - including radial-fibrous, feather, and scandulitic dendrite morphologies and tufa clasts. At least two episodes of bone incorporation are preserved in the quarry based on their stratigraphic position and lithologic associations. The unique depositional setting in and around the Crystal Geyser Dinosaur Quarry appears to have been favorable for the preservation of vertebrate fossils and provides insight into early Cretaceous environments in North America. Copyright ?? 2007, SEPM (Society for Sedimentary Geology).

Sedimentary characteristics and depositional model of a Paleocene-Eocene salt lake in the Jiangling Depression, China

NASA Astrophysics Data System (ADS)

Yu, Xiaocan; Wang, Chunlian; Liu, Chenglin; Zhang, Zhaochong; Xu, Haiming; Huang, Hua; Xie, Tengxiao; Li, Haonan; Liu, Jinlei

2015-11-01

We studied the sedimentary characteristics of a Paleocene-Eocene salt lake in the Jiangling Depression through field core observation, thin section identification, scanning electron microscopy, and X-ray diffraction analysis. On the basis of sedimentary characteristics we have summarized the petrological and mineralogical characteristics of the salt lake and proposed 9 types of grade IV salt rhythms. The deposition shows a desalting to salting order of halite-argillaceous-mudstone-mud dolostonemud anhydrock-glauberite-halite. The relationship among grade IV rhythms, water salinity and climate fluctuations was analyzed. Based on the analysis of the relationship between boron content and mudstone color and by combining the mineralogy and sedimentary environment characteristics, we propose that the early and late Paleocene Shashi Formation in the Jiangling Depression was a paleolacustrine depositional environment with a high salt content, which is a representation of the shallow water salt lake depositional model. The middle Paleocene Shashi Formation and the early Eocene Xingouzui Formation were salt and brackish sedimentary environments with low salt content in a deep paleolake, which represents a deep salt lake depositional model.

Two distinct clinical courses of renal involvement in rheumatoid patients with AA amyloidosis.

PubMed

Uda, Hiroshi; Yokota, Akira; Kobayashi, Kumiko; Miyake, Tadao; Fushimi, Hiroaki; Maeda, Akira; Saiki, Osamu

2006-08-01

We conducted a prospective study to investigate whether a correlation exists between the clinical course of renal involvement and the pathological findings of renal amyloidosis in patients with rheumatoid arthritis (RA). Patients with RA of more than 5 years' duration and who did not show renal manifestations were selected and received a duodenal biopsy for the diagnosis of amyloidosis. After the diagnosis of AA amyloidosis, patients received a renal biopsy, and patterns of amyloid deposition were examined. We followed the renal functions (serum levels of blood urea nitrogen and creatinine) of patients diagnosed with AA amyloidosis for 5 years. We diagnosed 53 patients with AA amyloidosis and monitored the renal function of 38 of them for > 5 years. The histological patterns were examined; in the 38 patients there were appreciable variations in the patterns of amyloid deposition. In 27 patients, amyloid deposits were found exclusively in the glomerulus (type 1). In the other 11 patients, however, amyloid deposits were found selectively around blood vessels and were totally absent in the glomerulus (type 2). In type 1 patients with glomerular involvement, renal function deteriorated rapidly regardless of disease state; most patients received hemodialysis. In type 2 patients with purely vascular involvement, however, renal function did not deteriorate significantly. In patients with RA and AA amyloidosis, 2 distinct clinical courses in terms of renal involvement were identified. It is suggested that renal function does not deteriorate when amyloid deposition is totally lacking in the glomerulus.

Use of stream chemistry for monitoring acidic deposition effects in the Adirondack region of New York

USGS Publications Warehouse

Lawrence, G.B.; Momen, B.; Roy, K.M.

2004-01-01

Acid-neutralizing capacity (ANC) and pH were measured weekly from October 1991 through September 2001 in three streams in the western Adirondack Mountain region of New York to identify trends in stream chemistry that might be related to changes in acidic deposition. A decreasing trend in atmospheric deposition of SO42- was observed within the region over the 10-yr period, although most of the decrease occurred between 1991 and 1995. Both ANC and pH were inversely related to flow in all streams; therefore, a trend analysis was conducted on (i) the measured values of ANC and pH and (ii) the residuals of the concentration-discharge relations. In Buck Creek, ANC increased significantly (p 0.10). In Bald Mountain Brook, ANC and residuals of ANC increased significantly (p < 0.01), although the trend was diatonic-a distinct decrease from 1991 to 1996 was followed by a distinct increase from 1996 to 2001. In Fly Pond outlet, ANC and residuals of ANC increased over the study period (p < 0.01), although the trend of the residuals resulted largely from an abrupt increase in 1997. In general, the trends observed in the three streams are similar to results presented for Adirondack lakes in a previous study, and are consistent with the declining trend in atmospheric deposition for this region, although the observed trends in ANC and pH in streams could not be directly attributed to the trends in acidic deposition.

Continuous measurements of bronchial exposure induced by radon decay products during inhalation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Iwaoka, Kazuki; Tokonami, Shinji; Yonehara, Hidenori

2007-09-15

The deposition of radon decay products is not equal in each of the respiratory regions and as the presence of radon has been linked with an increase in lung cancer risk, it is important to calculate the deposition of radon decay products in each of the respiratory regions. Recently, many studies on the deposition of radon in respiratory regions have been simulated using wire screens. The systems and equipment used in those studies are not suitable for field measurements as their dimensions are relatively massive, nor can they measure continuously. We developed a continuous bronchial dosimeter (CBD) which is suitablemore » for field measurements. It was designed with specifications that allow it to be remain compact. The CBD simulates the deposition of radon decay products in the different respiratory regions by the use of a combination of wire screens. Deposition in the simulated regions of the lung can be continuously estimated in various environments. The ratio of activities deposited in a simulated nasal cavity (N) and tracheobronchial (TB) regions was calculated from the results of simultaneous measurements using CBD-R (reference), CBD-N (nasal), and CBD-TB (tracheobronchial) measurement units. After aerosols were injected into the radon chamber, the ratio of N and TB depositions decreased. This results indicate that the CBD gave a good response to changes in the environment. It was found that the ratio of N and TB deposition also varied with time in each actual environment.« less

Sedimentary Environment Changes between Tsunami Events in the Central Fukushima Prefecture, Japan

NASA Astrophysics Data System (ADS)

Kusumoto, S.; Goto, T.; Satake, K.; Sugai, T.; Yoneda, M.; Omori, T.; Ozaki, H.

2016-12-01

Many tsunami deposits were found in the Tohoku region, Japan from recent and past tsunamis. Study of tsunami deposits is particularly important in the central to southern Fukushima Prefecture, which is the southern limit of the distributions of tsunami deposits of the 869 Jogan, 1454 Kyotoku and 1611 Keicho-Sanriku earthquakes. Previous studies reported that there were at least five tsunami deposits (EV1-EV5) consisted of fine-middle sand and the sedimentary environment was inner-bay or lagoon for the past 2,600 years (Goto and Aoyama, 2005; JpGU, Oikawa et al., 2011; JpGU, Oota and Hoyanagi, 2014; GSJ, Kusumoto et al., 2016; JpGU). However, the sedimentary environment changes between or across historical tsunamis have not been examined. In this study, we try to estimate the sedimentary environment changes using Total Organic Carbon (TOC), Total Nitrogen (TN) concentrations and organic Carbon-to-Nitrogen (C/N) ratio. We took 13 geological core samples of length 2.0-2.5 m at 11 locations 0.6-2.7 km from the coast. The deposits consisted of silt and massive sand with graded beddings, laminas and rip-up clasts. For samples, we performed grain-size analysis, radiocarbon age measurement and CN elemental analysis. We found three interesting characteristics. First, grain size of ordinary deposits between EV4 and EV5 tend to fine upward slightly. It suggests that tidal current became gradually weak. Second, C/N ratio is about 5-10 at every depth, meaning that organic material source was phytoplankton or zooplankton (Müller, 1977; GCA). Finally, TOC and TN concentrations slowly increase between EV4 and EV5, and they rapidly decrease across EV3 and EV4. Their slow increases correspond to sedimentary environment change from anaerobic to aerobic, whereas rapid decreases correspond to sedimentary environment change from aerobic to anaerobic. These characteristics might indicate development of sand bar between tsunami events and sudden collapse of sand bar by historical tsunamis.

North-south geological differences between the residual polar caps on Mars

USGS Publications Warehouse

Thomas, P.C.; Malin, M.C.; Edgett, K.S.; Carr, M.H.; Hartmann, W.K.; Ingersoll, A.P.; James, P.B.; Soderblom, L.A.; Veverka, J.; Sullivan, R.

2000-01-01

Polar processes can be sensitive indicators of global climate, and the geological features associated with polar ice caps can therefore indicate evolution of climate with time. The polar regions on Mars have distinctive morphologic and climatologic features: thick layered deposits, seasonal CO2 frost caps extending to mid latitudes, and near-polar residual frost deposits that survive the summer. The relationship of the seasonal and residual frost caps to the layered deposits has been poorly constrained, mainly by the limited spatial resolution of the available data. In particular, it has not been known if the residual caps represent simple thin frost cover or substantial geologic features. Here we show that the residual cap on the south pole is a distinct geologic unit with striking collapse and erosional topography; this is very different from the residual cap on the north pole, which grades into the underlying layered materials. These findings indicate that the differences between the caps are substantial (rather than reflecting short-lived differences in frost cover), and so support the idea of long-term asymmetry in the polar climates of Mars.

Textural, compositional, and sulfur isotope variations of sulfide minerals in the Red Dog Zn-Pb-Ag deposits, Brooks Range, Alaska: Implications for Ore Formation

USGS Publications Warehouse

Kelley, K.D.; Leach, D.L.; Johnson, C.A.; Clark, J.L.; Fayek, M.; Slack, J.F.; Anderson, V.M.; Ayuso, R.A.; Ridley, W.I.

2004-01-01

The Red Dog Zn-Pb deposits are hosted in organic-rich mudstone and shale of the Mississippian Kuna Formation. A complex mineralization history is defined by four sphalerite types or stages: (1) early brown sphalerite, (2) yellow-brown sphalerite, (3) red-brown sphalerite, and (4) late tan sphalerite. Stages 2 and 3 constitute the main ore-forming event and are volumetrically the most important. Sulfides in stages 1 and 2 were deposited with barite, whereas stage 3 largely replaces barite. Distinct chemical differences exist among the different stages of sphalerite. From early brown sphalerite to later yellow-brown sphalerite and red-brown sphalerite, Fe and Co content generally increase and Mn and Tl content generally decrease. Early brown sphalerite contains no more than 1.9 wt percent Fe and 63 ppm Co, with high Mn (up to 37 ppm) and Tl (126 ppm), whereas yellow-brown sphalerite and red-brown sphalerite contain high Fe (up to 7.3 wt %) and Co (up to 382 ppm), and low Mn (<27 ppm) and Tl (<37 ppm). Late tan sphalerite has distinctly lower Fe (< 0.9 wt %) and higher Tl (up to 355 ppm), Mn (up to 177 ppm), and Ge (426 ppm), relative to earlier sphalerite. Wide ranges in concentrations of Ag, Cu, Pb, and Sb characterize all sphalerite types, particularly yellow-brown sphalerite and red-brown sphalerite, and most likely reflect submicroscopic inclusions of galena, chalcopyrite and/or tetrahedrite in the sphalerite. In situ ion microprobe sulfur isotope analyses show a progression from extremely low ??34S values for stage 1 (as low as -37.20???) to much higher values for yellow-brown sphalerite (mean of 3.3???; n = 30) and red-brown sphalerite (mean of 3.4; n = 20). Late tan sphalerite is isotopically light (-16.4 to -27.2???). The textural, chem ical, and isotopic data indicate the following paragenesis: (1) deposition of early brown sphalerite with abundant barite, minor pyrite, and trace galena immediately beneath the sea floor in unconsolidated mud; (2) deposition of yellow-brown sphalerite during subsea-floor hydrothermal recrystallization and coarsening of preexisting barite; (3) open-space deposition of barite, red-brown sphalerite and other sulfides in veins and coeval replacement of barite; and (4) postore sulfide deposition, including the formation of late tan sphalerite breccias. Stage 1 mineralization took place in a low-temperature environment where fluids rich in Ba mixed with pore water or water-column sulfate to form barite, and metals combined with H2S derived from bacterial sulfate reduction to form sulfides. Higher temperatures and salinities and relatively oxidized ore-stage fluids (stages 2 and 3) compared with stage 1 were probably important controls on the abundances and relative amounts of metals in the fluids and the resulting sulfide chemistry. Textural observations and isotopic data show that preexisting barite was reductively dissolved, providing a source of H2S for sulfide mineral formation. In stage 3, the continued flow of hydrothermal fluids caused thermal alteration of organic-rich mudstones and a build-up of methane that led to fluid overpressuring, hydrofracturing, and vein formation. Barite, red-brown sphalerite, and other sulfides were deposited in the veins, and preexisting barite was pervasively replaced by red-brown sphalerite. Hydrothermal activity ceased until Jurassic time when thrusting and large-scale fluid flow related to the Brookian orogeny remobilized and formed late tan sphalerite in tectonic breccias. ?? 2004 by Economic Geology.

Fast Scanning Calorimetry Studies of Supercooled Liquids and Glasses

NASA Astrophysics Data System (ADS)

Bhattacharya, Deepanjan

This dissertation is a compilation of research results of extensive Fast Scanning Calorimetry studies of two non-crystalline materials: Toluene and Water. Motivation for fundamental studies of non-crystalline phases, a brief overview of glassy materials and concepts and definitions related to them is provided in Chapter 1. Chapter 2 provides fundamentals and details of experimental apparata, experimental protocol and calibration procedure. Chapter 3 & 4 provides extensive studies of stable non-crystalline toluene films of micrometer and nanometer thicknesses grown by vapor deposition at distinct deposition rates and temperatures and probed by Fast Scanning Calorimetry. Fast scanning calorimetry is shown to be extremely sensitive to the structure of the vapor-deposited phase and was used to characterize simultaneously its kinetic stability and its thermodynamic properties. According to our analysis, transformation of vapor -deposited samples of toluene during heating with rates in excess 100,000 K/s follows the zero-order kinetics. The transformation rate correlates strongly with the initial enthalpy of the sample, which increases with the deposition rate according to sub-linear law. Analysis of the transformation kinetics of vapor deposited toluene films of various thicknesses reveal a sudden increase in the transformation rate for films thinner than 250 nm. The change in kinetics correlates with the surface roughness scale of the substrate, which is interpreted as evidence for kinetic anisotropy of the samples. We also show that out-of-equilibrium relaxation kinetics and possibly the enthalpy of vapor-deposited (VD) films of toluene are distinct from those of ordinary supercooled (OS) phase even when the deposition takes place at temperatures above the glass softening (Tg). The implications of these findings for the formation mechanism and structure of vapor deposited stable glasses are discussed. Chapter 5 and 6 provide detailed Fast Scanning Calorimetry studies of amorphous solid water in bulk and confining geometry (ultrathin films and nano-aggregates). Bulk-like water samples were prepared by vapor-deposition on the surface of a tungsten filament near 140 K where vapor-deposition results in low enthalpy glassy water films. The vapor deposition approach was also used to grow nano-aggregates (2- 20 nm thick) and multiple ultrathin (approximately 50 nm thick) water films alternated with benzene and methanoic films of similar dimensions. When heated from cryogenic temperatures, the ultrathin water films underwent a well manifested glass softening transition at temperatures 20 degrees below the onset of crystallization. The thermograms of nano-aggregates of ASW films show two endotherms at 40 and 10 K below the onset temperatures of crystallization. However, no such transition was observed in bulk-like water samples prior to their crystallization. These results indicate that water in confined geometry demonstrates glass softening dynamics which are dramatically distinct from those of the bulk phase. We attribute these differences to water's interfacial glass transition which occurs at temperatures tens of degrees lower than that in the bulk. Implications of these finding for past studies of glass softening dynamics in various glassy water samples are discussed in chapter 5 and 6.

The Cretaceous Tetori biota in Japan and its evolutionary significance for terrestrial ecosystems in Asia

USGS Publications Warehouse

Matsukawa, M.; Ito, M.; Nishida, N.; Koarai, K.; Lockley, M.G.; Nichols, D.J.

2006-01-01

Cretaceous nonmarine deposits are widely distributed on the Asian continent and include various kinds of zoo- and phyto-assemblages. The Tetori Group is one of the most important Mesozoic terrestrial deposits in East Asia, and for this reason its geology, stratigraphy, and biota have been studied intensively by our group for more than a decade. We present the main results herein. We confirm that formations as lithostratigraphic units are the best geological correlation tools for the Tetori Group and the best tools for a geological mapping of the group. Although subgroups have previously been used for correlation, proper designation and evaluation of subgroups is required if they are to be used effectively, and we show that previous geological correlation of the Tetori Group has been confused by inappropriate definition of these subgroups. We located fossil localities including reported zoo- and phyto-assemblages in the framework of formations correlated by our stratigraphy. The occurrence of zoo-assemblages was probably controlled by environments (i.e., most are in situ), but phyto-assemblages were mostly transported and rapidly buried by high-energy river systems. Although two distinct dinosaur faunas and four floras have been named for the zoo- and phyto-assemblages in the Tetori Group, in reality there is only one Tetori Dinosaur Fauna and one Tetori Flora, as proved by careful correlation. Two types of zoo-assemblages co-occur in the Tetori Group: vertebrate species whose ancestors flourished in the Jurassic (as found in China), and their descendants from the Late Cretaceous. As the latter modern type of assemblage is more abundant than the former, changeable environments at the continental margin probably accelerated evolution of more modern species. We can employ nonmarine molluscan species as geological correlation tools in some cases, i.e., when their taxon ranges are well-confirmed by independent evidence. However, because freshwater molluscan species and terrestrial vertebrate species had many opportunities to move to optimum habitat as environments changed through time on the Cretaceous Asian continent, their correlation potential is uncertain. Many nonmarine molluscan species from the Japanese and Chinese Cretaceous had their stratigraphic occurrences controlled by changing environments. ?? 2005 Elsevier Ltd. All rights reserved.

Sedimentary record of seismic events in the Eocene Green River Formation and its implications for regional tectonics on lake evolution (Bridger Basin, Wyoming)

NASA Astrophysics Data System (ADS)

Törő, Balázs; Pratt, Brian R.

2016-10-01

Outcrops and cores from the top of the lacustrine Tipton Member and the base of the Wilkins Peak Member ( 51.5 Ma) of the Eocene Green River Formation, Bridger Basin in southwestern Wyoming yield a wide variety of sedimentary deformation features many of which are laterally extensive for more than 50 km. They include various types of folds, load structures, pinch-and-swell structures, microfaults, breccias and sedimentary dikes. In most cases deformation is represented by hybrid brittle-ductile structures exhibiting lateral variation in deformation style. These occur in low-energy, profundal organic-rich carbonate mudstones (oil shales), trona beds, tuffs, and profundal to sublittoral silty carbonate deposited in paleolake Gosiute. The deformation is not specific to the depositional environment because sedimentary units stratigraphically higher with similar facies show no deformation. The studied interval lacks any evidence for possible trigger mechanisms intrinsic to the depositional environment, such as strong wave action, rapid sediment loading, evaporite dissolution and collapse, or desiccation, so 'endogenic' causes are ruled out. Thus, the deformation features are interpreted as seismites, and change in deformation style and inferred increase in intensity towards the south suggest that the earthquakes were sourced from the nearby Uinta Fault System. The 22 levels exhibiting seismites recognized in cores indicate earthquakes with minimum magnitudes between 6 and 7, minimum epicentral intensity (MCS) of 9, and varying recurrence intervals in the seismic history of the Uinta Fault System, with a mean apparent recurrence period of 8.1 k.y. using average sedimentation rates and dated tuffs; in detail, however, there are two noticeably active periods followed by relative quiescence. The stratigraphic position of these deformed intervals also marks the transition between two distinct stages in lake evolution, from the balanced-filled Tipton Member to the overlying, underfilled Wilkins Peak Member. Thus, these seismites are evidence for regional-scale changes in lacustrine sedimentation of Eocene Lake Gosiute in response to syndepositional tectonic activity. Analysis of synsedimentary deformation features is, therefore, a promising yet under-utilized tool to trace the tectonic evolution of lacustrine deposits of the Green River Formation and other tectonically active marine and non-marine basins.

Post-obduction carbonate system development in New Caledonia (Népoui, Lower Miocene)

NASA Astrophysics Data System (ADS)

Maurizot, Pierre; Cabioch, Guy; Fournier, François; Leonide, Philippe; Sebih, Salim; Rouillard, Pierrick; Montaggioni, Lucien; Collot, Julien; Martin-Garin, Bertrand; Chaproniere, George; Braga, Juan C.; Sevin, Brice

2016-01-01

For the first time, depositional models of Lower Miocene carbonate systems from New Caledonia (Southwest Pacific) are proposed, on the basis of a sedimentological and paleoenvironmental study of both cores and outcrops. In the Népoui area, two distinct stages of carbonate ramp development (Aquitanian Lower Népoui and Burdigalian Upper Népoui carbonate systems), separated by a phase of siliciclastic deltaic deposition, are evidenced. The post-obduction marine transgression of the Western New Caledonian margin occurred at approximately 24 Ma and is characterized by the development of an aggrading foraminiferal-coralline algal-scleractinian ramp system ("Chapeau Chinois Limestone") during the early Aquitanian (24-23 Ma). A retrogradational event is evidenced at approximately 23 Ma followed by the development of a shallowing upward carbonate unit (Operculina "Green Sands" and Xuudhen Limestone) during the late Aquitanian. This unit is topped by a major erosional unconformity overlain by conglomeratic deposits ("Pindaï conglomerates"), and interpreted to record a significant uplift at around 21-19 Ma. During the Burdigalian, a marine transgression occurred at around 19 Ma, followed by the development of a low-angle carbonate ramp or open platform ("Népü Limestone") up to the late Burdigalian (19-17 Ma). In both Aquitanian and Burdigalian carbonate ramps, extensive sea-grass meadows are shown to have colonized the proximal ramp environments within the euphotic zone. In the Aquitanian carbonate ramp (Lower Népoui Formation), carbonate production within sea-grass meadows is dominated by large benthic foraminifera, together with red algae and sparse scleractinians. Mesophotic environments are characterized by large and flat lepidocyclinids, rhodoliths and platy corals whereas in deeper oligophotic settings significant carbonate producers consist mainly of large and flat benthic foraminifera. In the Burdigalian carbonate ramp (Upper Népoui Formation), porcellaneous foraminifera thriving in sea-grass meadows together with red algae and scattered coral colonies characterize the carbonate production in the euphotic zone. Antecedent topography is regarded as a major factor controlling the extension of carbonate systems at regional and local scale. The thickness and development pattern of Lower Miocene deposits from Népoui are dominantly controlled by tectonic subsidence. Finally, extensive sea-grass development promoted the dominance of foralgal carbonate production within the euphotic zone.

Sedimentology and paleoenvironments of a new fossiliferous late Miocene-Pliocene sedimentary succession in the Rukwa Rift Basin, Tanzania

NASA Astrophysics Data System (ADS)

Mtelela, Cassy; Roberts, Eric M.; Hilbert-Wolf, Hannah L.; Downie, Robert; Hendrix, Marc S.; O'Connor, Patrick M.; Stevens, Nancy J.

2017-05-01

This paper presents a detailed sedimentologic investigation of a newly identified, fossiliferous Late Neogene sedimentary succession in the Rukwa Rift Basin, southwestern Tanzania. This synrift deposit is a rare and significant new example of a fossiliferous succession of this age in the Western Branch of East Africa Rift System. The unit, informally termed the lower Lake Beds succession, is late Miocene to Pliocene in age based on cross-cutting relationships, preliminary biostratigraphy, and U-Pb geochronology. An angular unconformity separates the lower Lake Beds from underlying Cretaceous and Oligocene strata. Deposition was controlled by rapid generation of accommodation space and increased sediment supply associated with late Cenozoic tectonic reactivation of the Rukwa Rift and synchronous initiation of the Rungwe Volcanic Centre. The lower Lake Beds, which have thus far only been identified in three localities throughout the Rukwa Rift Basin, are characterized by two discrete lithologic members (herein A and B). The lower Member A is a volcanic-rich succession composed mostly of devitrified volcanic tuffs, and volcaniclastic mudstones and sandstones with minor conglomerates. The upper Member B is a siliciclastic-dominated succession of conglomerates, sandstones, mudstones and minor volcanic tuffs. Detailed facies analysis of the lower Lake Beds reveals various distinctive depositional environments that can be grouped into three categories: 1) alluvial fan; 2) fluvial channel; and 3) flood basin environments, characterized by volcanoclastic-filled lakes and ponds, abandoned channel-fills and pedogenically modified floodplains. Member A represents a shallow lacustrine setting filled by tuffaceous sediments, which grade up into a system of alluvial fans and high-energy, proximal gravel-bed braided rivers. An unconformity marks the contact between the two members. Member B shows an upward transition from a high-energy, gravel-bed braided river system to a sandy braided river system with increasingly abundant floodplain deposits and well-developed paleosols. Vertebrate fossils are sparse in member A, but common in member B, preserved both within pedogenic soil horizons and as isolated elements and microsites within fluvial channel facies associations. Faunal remains include fishes, turtles and crocodylians, along with well-preserved mammal cranial and post-cranial remains. In addition, freshwater gastropod shells are locally present in member A and continental trace fossils, including abundant fossilized termite nests, are present in both members.

Seafloor environments in Cape Cod Bay, a large coastal embayment

USGS Publications Warehouse

Knebel, H.J.; Rendigs, R. R.; List, J.H.; Signell, R.P.

1996-01-01

Cape Cod Bay is a glacial, semi-enclosed embayment that has a patchy distribution of modern seafloor sedimentary environments of erosion or nondeposition, deposition, and sediment reworking. Sidescan-sonar records and supplemental bathymetric, sedimentary, subbottom, and physical- oceanographic data indicate that the characteristics and distribution of these three categories of bottom environments are controlled by a combination of geologic and oceanographic processes that range from episodic to long-term and from regional to local. (1) Environments of erosion or nondeposition comprise exposares of bedrock, glacial drift, and coarse lag deposits that contain sediments (where present) ranging from boulder fields to gravelly coarse-to-medium sands. These environments are dominant on the shallow margins of the bay (water depths <30 m) where they reflect sediment resuspension, winnowing, and transport during modern northerly storms. (2) Environments of deposition are blanketed by fine-grained sediments ranging from muds to muddy fine sands. These environments are dominant across the floor of the central basin (water depths= 30-60 m) where fine- grained sediments (derived from regional and local sources and emplaced primarily during episodic wind- and density-driven flow) settle through the water column and accumulate under weak bottom currents during nonstorm conditions. (3) Environments of sediment reworking contain patches with diverse textures ranging from gravelly sands to muds. These environments occupy much of the transitional slopes between the margins and the basin floor and reflect a combination of erosion and deposition. The patchy distribution of sedimentary environments within the bay reflects not only regional changes in processes between the margins and the basin but local changes within each part of the bay as well. Small-scale patchiness is caused by local changes in the strengths of wave- and wind-driven currents and (on the margins) by local variations in the supply of fine-grained sediments. This study indicates areas within Cape Cod Bay where fine-grained sediments and associated contaminants are likely to be either moved or deposited. It also provides a guide to the locations and variability of benthic habitats.

Seafloor environments in Cape Cod Bay, a large coastal embayment

USGS Publications Warehouse

Knebel, H.J.; Rendigs, R. R.; List, J.H.; Signell, Richard P.

1996-01-01

Cape Cod Bay is a glacial, semi-enclosed embayment that has a patchy distribution of modern seafloor sedimentary environments of erosion or nondeposition, deposition, and sediment reworking. Sidescan-sonar records and supplemental bathymetric, sedimentary, subbottom, and physical-oceanographic data indicate that the characteristics and distribution of these three categories of bottom environments are controlled by a combination of geologic and oceanographic processes that range from episodic to long-term and from regional to local. (1) Environments of erosion or nondeposition comprise exposures of bedrock, glacial drift, and coarse lag deposits that contain sediments (where present) ranging from boulder fields to gravelly coarse-to-medium sands. These environments are dominant on the shallow margins of the bay (water depths < 30 m) where they reflect sediment resuspension, winnowing, and transport during modern northerly storms. (2) Environments of deposition are blanketed by fine-grained sediments ranging from muds to muddy fine sands. These environments are dominant across the floor of the central basin (water depths = 30–60 m) where fine-grained sediments (derived from regional and local sources and emplaced primarily during episodic wind- and density-driven flow) settle through the water column and accumulate under weak bottom currents during nonstorm conditions. (3) Environments of sediment reworking contain patches with diverse textures ranging from gravelly sands to muds. These environments occupy much of the transitional slopes between the margins and the basin floor and reflect a combination of erosion and deposition.The patchy distribution of sedimentary environments within the bay reflects not only regional changes in processes between the margins and the basin but local changes within each part of the bay as well. Small-scale patchiness is caused by local changes in the strengths of wave- and wind-driven currents and (on the margins) by local variations in the supply of fine-grained sediments.This study indicates areas within Cape Cod Bay where fine-grained sediments and associated contaminants are likely to be either moved or deposited. It also provides a guide to the locations and variability of benthic habitats.

Handbook on surficial uranium deposits. Chapter 3. World distribution relative to climate and physical setting

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carlisle, D

1983-01-01

This chapter discusses regional controls which affect the world distribution of surficial chemogenic uranium deposits. The most important of these are (1) climate, (2) geomorphology, including physiographic and climatic stability, and (3) provenance, i.e., the weathering terrain from which uranium and associated substances are derived. The three economically important environments are the calcrete environment, simple evaporative environments and paludal environments. Of these three categories, the calcrete uranium environment is probably the most uniquely constrained in terms of regional climate, geomorphic setting, provenance (vanadium as well as uranium) and especially the need for long term stability of both climate and physiography.more » Purely evaporative deposits, though subject to some of the same kinds of constraints, can also reflect local circumstances and a wider range of climates, physiographic settings, and source terrains. The third category encompassing bogs, marshes and organic-rich playas can form under an even wider range of climates and settings provided only that organic materials accumulate in abundance and are contacted by uranium-bearing waters. For all of these reasons and also because of the great economic importance of the calcrete environment as well as its relative novelty and complexity the discussion in this chapter is focused on calcrete, dolocrete and gypcrete uranium deposits. Objective data are reviewed first follwed by inferences and suggestions. 13 figures.« less

Regional stratigraphy and subsurface geology of Cenozoic deposits, Gulf Coastal Plain, south-central United States

USGS Publications Warehouse

Hosman, R.L.

1991-01-01

Although Cenozoic deposits are not uniformly differentiated, interstate correlations of major Paleocene and Eocene units are generally established throughout the area. Younger deposits are not as well differentiated. Some stratigraphic designations made at surface exposures cannot be extended into the sub-surface, and the scarcity of distinct geologic horizons has hampered differentiation on a regional scale. The complexities of facies development in Oligocene and younger coastal deposits preclude the development of extensive recognizable horizons needed for stratigraphic applications. Coastal deposits are a heterogeneous assemblage of deltaic, lagoonal, lacustrine, palustrine, eolian, and fluvial clastic facies and local calcareous reef facies. Even major time boundaries, as between geologic series, are not fully resolved. Surficial Quaternary deposits overlie the truncated subcrops of Tertiary strata and generally are distinguishable, although some contacts between Pleistocene and underlying Pliocene deposits have been a ?lstoncal source of controversy. Glacially related terraces are characteristic of the Pleistocene Epoch, and alluvium of aggrading streams typifies the Holocene. 

An occurrence model for the national assessment of volcanogenic beryllium deposits

USGS Publications Warehouse

Foley, Nora K.; Seal, Robert R.; Piatak, Nadine M.; Hetland, Brianna

2010-01-01

The general occurrence model summarized here is intended to provide a descriptive basis for the identification and assessment of undiscovered beryllium deposits of a type and style similar to those found at Spor Mountain, Juab County, Utah. The assessment model is restricted in its application in order to provide a coherent basis for assessing the probability of the occurrence of similar economic deposits using the current U.S. Geological Survey methodology. The model is intended to be used to identify tracts of land where volcanogenic epithermal replacement-type beryllium deposits hosted by metaluminous to peraluminous rhyolite are most likely to occur. Only a limited number of deposits or districts of this type are known, and only the ores of the Spor Mountain district have been studied in detail. The model highlights those distinctive aspects and features of volcanogenic epithermal beryllium deposits that pertain to the development of assessment criteria and puts forward a baseline analysis of the geoenvironmental consequences of mining deposits of this type.

Remote Analysis of Lunar Pyroclastic Glass Deposits by LRO Diviner

NASA Technical Reports Server (NTRS)

Allen, Carlton C.; Greenhagen, Benjamin T.; Donaldson Hanna, Kerri; Paige, David A.

2011-01-01

Telescope observations and orbital images of the Moon reveal at least 75 deposits, often tens to hundreds of km across, that mantle mare or highland surfaces. These deposits are interpreted as the products of pyroclastic eruptions and designated herein as lunar pyroclastic deposits (LPD). They are understood to be composed primarily of sub-millimeter beads of basaltic composition, ranging from glassy to partially-crystallized. Delano documented 25 distinct pyroclastic bead compositions in lunar soil samples, though the source deposits for most of these beads have not been identified. The pyroclastic deposits are important for many reasons. Petrology experiments and modeling have demonstrated that the pyroclastic glasses are the deepest-sourced and most primitive basalts on the Moon. Recent analyses have documented the presence of water in these glasses, demonstrating that the lunar interior is considerably more volatile-rich than previously understood. Experiments have shown that the iron-rich pyroclastic glasses release the highest percentage of oxygen of any Apollo soils, making these deposits promising lunar resources.

The Kharapeh orogenic gold deposit: Geological, structural, and geochemical controls on epizonal ore formation in West Azerbaijan Province, Northwestern Iran

USGS Publications Warehouse

Niroomand, Shojaeddin; Goldfarb, Richard J.; Moore, Farib; Mohajjel, Mohammad; Marsh, Erin E.

2011-01-01

The Kharapeh gold deposit is located along the northwestern margin of the Sanandaj–Sirjan Zone (SSZ) in the West Azerbaijan province, Iran. It is an epizonal orogenic gold deposit formed within the deformed zone between central Iran and the Arabian plate during the Cretaceous–Tertiary Zagros orogeny. The deposit area is underlain by Cretaceous schist and marble, as well as altered andesite and dacite dikes. Structural analysis indicates that the rocks underwent tight to isoclinal recumbent folding and were subsequently co-axially refolded to upright open folds during a second deformation. Late- to post-tectonic Cenozoic granites and granodiorites occur northeast of the deposit area. Mineralization mainly is recognized within NW-trending extensional structures as veins and breccia zones. Normal faults, intermediate dikes, and quartz veins, oriented subparallel to the axial surface of the Kharapeh antiform, indicate synchronous extension perpendicular to the fold axis during the second folding event. The gold-bearing quartz veins are >1 km in length and average about 6 m in width; breccia zones are 10–50 m in length and ≤1 m in width. Hydrothermal alteration mainly consists of silicification, sulfidation, chloritization, sericitization, and carbonatization. Paragenetic relationships indicate three distinct stages—replacement and silicification, brecciation and fracture filling, and cataclastic brecciation—with the latter two being gold-rich. Fluid inclusion data suggest mineral deposition at temperatures of at least 220–255°C and depths of at least 1.4–1.8 km, from a H2O–CO2±CH4 fluid of relatively high salinity (12–14 wt.% NaCl equiv.), which may reflect metamorphism of passive margin carbonate sequences. Ore fluid δ18O values between about 7‰ and 9‰ suggest no significant meteoric water input, despite gold deposition in a relatively shallow epizonal environment. Similarities to other deposits in the SSZ suggest that the deposit formed as part of a diachronous gold event during the middle to late Tertiary throughout the SSZ and during the final stages of the Zagros orogeny. The proximity of Kharapeh to the main tectonic suture of the orogen, well-developed regional fold systems with superimposed complex fracture geometries, and recognition of nearby volcanogenic massive sulfide systems that suggest a region characterized by sulfur- and metal-rich crustal rocks, collectively indicate an area of the SSZ with high favorability for undiscovered gold resources.

The nummulithoclast event within the Lower Eocene in the Southern Tethyan margin: Mechanisms involved, analogy with the filament event and climate implication (Kairouan, Central Tunisia)

NASA Astrophysics Data System (ADS)

Mardassi, Besma

2017-10-01

Early Eocene deposits in Tunisia are marked by clear variations in terms of facies and thickness. Each facies corresponds to an appropriate depositional environment. Shallow water deposits pass gradually offshore into deeper carbonates along a homoclinal ramp. In Central Tunisia, detailed investigation of carbonate facies under transmitted light shows a particular richness of the middle part of Early Eocene deposits in nummulithoclasts. These facies are often frequent within corrugated banks. They are overlaying Globigerina rich well-bedded limestones and overlain by nummulites and Discocyclina rich massively-bedded carbonates. Nummulithoclasts occurrence is recorded on field by an abrupt vertical change from autochthonous thinly-bedded limestones to massively-bedded fossiliferous carbonates. Change concerns structures, textures and limestones' composition. Nummulithoclasts are associated either to planktonic micro-organisms or to benthic fauna and phosphates grains. The middle and the upper parts of the Early Eocene deposits, particularly, fossilize hummocky cross-stratifications and megaripples. Their presence advocates the role of energetic currents in sweeping nummulites from lower circatidal to upper bathyal environments. The absence of a slope break helped the settling of reworked nummulites within deeper environments. The abrupt change, nummulithoclast associations and current structures arouse reflection and make them not reliable to characterize depositional environments. However, their preferential occurrence within the middle part of Early Eocene deposits and the tight linkage with storm activity lead them to be considered as event. The large scale hummocks recorded on field suggests that nummulite fragmentation was triggered by tropical cyclones rather than humble storms. The frequent occurrence of cyclones which correspond to low pressure atmospheric systems seems in relation with a global warming enhancing the sea surface temperature.

Microbial Diversity of Impact-Generated Habitats

NASA Astrophysics Data System (ADS)

Pontefract, Alexandra; Osinski, Gordon R.; Cockell, Charles S.; Southam, Gordon; McCausland, Phil J. A.; Umoh, Joseph; Holdsworth, David W.

2016-10-01

Impact-generated lithologies have recently been identified as viable and important microbial habitats, especially within cold and arid regions such as the polar deserts on Earth. These unique habitats provide protection from environmental stressors, such as freeze-thaw events, desiccation, and UV radiation, and act to trap aerially deposited detritus within the fissures and pore spaces, providing necessary nutrients for endoliths. This study provides the first culture-independent analysis of the microbial community structure within impact-generated lithologies in a Mars analog environment, involving the analysis of 44,534 16S rRNA sequences from an assemblage of 21 rock samples that comprises three shock metamorphism categories. We find that species diversity increases (H = 2.4-4.6) with exposure to higher shock pressures, which leads to the development of three distinct populations. In each population, Actinobacteria were the most abundant (41%, 65%, and 59%), and the dominant phototrophic taxa came from the Chloroflexi. Calculated porosity (a function of shock metamorphism) for these samples correlates (R2 = 0.62) with inverse Simpson indices, accounting for overlap in populations in the higher shock levels. The results of our study show that microbial diversity is tied to the amount of porosity in the target substrate (as a function of shock metamorphism), resulting in the formation of distinct microbial populations.

Geologic youth of galapagos islands confirmed by marine stratigraphy and paleontology.

PubMed

Hickman, C S; Lipps, J H

1985-03-29

Six distinctive types of fossiliferous marine deposits occur on the Galádpagos Islands that provide evidence for the age of emergence of the islands above sea level and hence a maximum age for the islands' terrestrial biota. These subtidal to supratidal deposits include (i) volcanic tuffs with fossils, (ii) limestones and sandstones interbedded with basalt, (iii) terrace deposits, (iv) beach rock, (v) supratidal talus deposits, and (vi) recently uplifted tidal and subtidal rocks and sand. With the exception of (vi), the deposits were previously assigned ages varying from Miocene to Pleistocene, but all are less than about 2 million years old. This age, together with independently determined geologic ages, indicate that the islands emerged from the sea relatively recently and that all evolution of the islands' unique terrestrial biota occurred within the past 3 to 4 million years.

Interplanetary Radiation and Internal Charging Environment Models for Solar Sails

NASA Technical Reports Server (NTRS)

Minow, Joseph I.; Altstatt, Richard L.; NeegaardParker, Linda

2005-01-01

A Solar Sail Radiation Environment (SSRE) model has been developed for defining charged particle environments over an energy range from 0.01 keV to 1 MeV for hydrogen ions, helium ions, and electrons. The SSRE model provides the free field charged particle environment required for characterizing energy deposition per unit mass, charge deposition, and dose rate dependent conductivity processes required to evaluate radiation dose and internal (bulk) charging processes in the solar sail membrane in interplanetary space. Solar wind and energetic particle measurements from instruments aboard the Ulysses spacecraft in a solar, near-polar orbit provide the particle data over a range of heliospheric latitudes used to derive the environment that can be used for radiation and charging environments for both high inclination 0.5 AU Solar Polar Imager mission and the 1.0 AU L1 solar missions. This paper describes the techniques used to model comprehensive electron, proton, and helium spectra over the range of particle energies of significance to energy and charge deposition in thin (less than 25 micrometers) solar sail materials.

Growth and demise of a Paleogene isolated carbonate platform of the Offshore Indus Basin, Pakistan: effects of regional and local controlling factors

NASA Astrophysics Data System (ADS)

Shahzad, Khurram; Betzler, Christian; Ahmed, Nadeem; Qayyum, Farrukh; Spezzaferri, Silvia; Qadir, Anwar

2018-03-01

Based on high-resolution seismic and well datasets, this paper examines the evolution and drowning history of a Paleocene-Eocene carbonate platform in the Offshore Indus Basin of Pakistan. This study uses the internal seismic architecture, well log data as well as the microfauna to reconstruct factors that governed the carbonate platform growth and demise. Carbonates dominated by larger benthic foraminifera assemblages permit constraining the ages of the major evolutionary steps and show that the depositional environment was tropical within oligotrophic conditions. With the aid of seismic stratigraphy, the carbonate platform edifice is resolved into seven seismic units which in turn are grouped into three packages that reflect its evolution from platform initiation, aggradation with escarpment formation and platform drowning. The carbonate factory initiated as mounds and patches on a Cretaceous-Paleocene volcanic complex. Further, the growth history of the platform includes distinct phases of intraplatform progradation, aggradation, backstepping and partial drownings. The youngest succession as late-stage buildup records a shift from benthic to pelagic deposition and marks the final drowning in the Early Eocene. The depositional trend of the platform, controlled by the continuing thermal subsidence associated with the cooling of volcanic margin lithosphere, was the major contributor of the accommodation space which supported the vertical accumulation of shallow water carbonate succession. Other factors such as eustatic changes and changes in the carbonate producers as a response to the Paleogene climatic perturbations played secondary roles in the development and drowning of these buildups.

Early Permian transgressive-regressive cycles: Sequence stratigraphic reappraisal of the coal-bearing Barakar Formation, Raniganj Basin, India

NASA Astrophysics Data System (ADS)

Bhattacharya, Biplab; Bhattacharjee, Joyeeta; Bandyopadhyay, Sandip; Banerjee, Sudipto; Adhikari, Kalyan

2018-03-01

The present research is an attempt to assess the Barakar Formation of the Raniganj Gondwana Basin, India, in the frame of fluvio-marine (estuarine) depositional systems using sequence stratigraphic elements. Analysis of predominant facies associations signify deposition in three sub-environments: (i) a river-dominated bay-head delta zone in the inner estuary, with transition from braided fluvial channels (FA-B1) to tide-affected meandering fluvial channels and flood plains (FA-B2) in the basal part of the succession; (ii) a mixed energy central basin zone, which consists of transitional fluvio-tidal channels (FA-B2), tidal flats, associated with tidal channels and bars (FA-B3) in the middle-upper part of the succession; and (iii) a wave-dominated outer estuary (coastal) zone (FA-B4 with FA-B3) in the upper part of the succession. Stacked progradational (P1, P2)-retrogradational (R1, R2) successions attest to one major base level fluctuation, leading to distinct transgressive-regressive (T-R) cycles with development of initial falling stage systems tract (FSST), followed by lowstand systems tract (LST) and successive transgressive systems tracts (TST-1 and TST-2). Shift in the depositional regime from regressive to transgressive estuarine system in the early Permian Barakar Formation is attributed to change in accommodation space caused by mutual interactions of (i) base level fluctuations in response to climatic amelioration and (ii) basinal tectonisms (exhumation/sagging) related to post-glacial isostatic adjustments in the riftogenic Gondwana basins.

Characterizing near-surface elemental layering on Mars using gamma-ray spectroscopy: A proof-of-principle experiment

NASA Astrophysics Data System (ADS)

Peplowski, Patrick N.; Wilson, Jack T.; Beck, Andrew W.; Burks, Morgan; Goldsten, John O.; Lawrence, David J.

2018-01-01

Gamma-ray spectroscopy investigations characterize the chemical composition of planetary surfaces by measuring element-characteristic gamma rays with energies of ∼100 keV to ∼9 MeV. Over this energy range, the mean free path of a gamma ray varies from about 1 to 25 cm, therefore gamma-ray measurements sample subsurface composition. Many elements emit gamma rays at multiple, often widely spaced energies, so gamma-ray measurements can in principle also be used to identify depth-dependent variations in subsurface composition. We report results from laboratory measurements and radiation transport modeling designed to demonstrate this capability. The laboratory measurements verified the presence of depth-dependent gamma-ray signatures, and were then used to benchmark radiation transport simulations that were used to model realistic Mars-like scenarios. The models indicate that compositionally distinct subsurface deposits, buried to depths of ∼80 cm (125 g/cm2), can be identified using gamma-ray measurements. Going beyond identification to characterization (burial depth, relative composition of the layers) of the deposits requires knowledge of the vertical and horizontal variability in the water content of the near-surface surface materials, the local Galactic Cosmic Ray environment (magnitude and energy distribution), the depth-dependent neutron flux, gamma-ray production cross sections, and knowledge of the composition and column density of the atmosphere. The results of our experiments and models provided a basis for examining the utility of using orbiter- and lander-based gamma-ray measurements to identify subsurface deposits on Mars.

Stratigraphy of lower to middle Paleozoic rocks of northern Nevada and the Antler orogeny

USGS Publications Warehouse

Ketner, Keith B.

2013-01-01

Commonly accepted concepts concerning the lower Paleozoic stratigraphy of northern Nevada are based on the assumption that the deep-water aspects of Ordovician to Devonian siliceous strata are due to their origin in a distant oceanic environment, and their presence where we find them is due to tectonic emplacement by the Roberts Mountains thrust. The concept adopted here is based on the assumption that their deep-water aspects are the result of sea-level rise in the Cambrian, and all of the Paleozoic strata in northern Nevada are indigenous to that area. The lower part of the Cambrian consists mainly of shallow-water cross-bedded sands derived from the craton. The upper part of the Cambrian, and part of the Ordovician, consists mainly of deep-water carbonate clastics carried by turbidity currents from the carbonate shelf in eastern Nevada, newly constructed as a result of sea-level rise. Ordovician to mid-Devonian strata are relatively deep-water siliceous deposits, which are the western facies assemblage. The basal contact of this assemblage on autochthonous Cambrian rocks is exposed in three mountain ranges and is clearly depositional in all three. The western facies assemblage can be divided into distinct stratigraphic units of regional extent. Many stratigraphic details can be explained simply by known changes in sea level. Upper Devonian to Mississippian strata are locally and westerly derived orogenic clastic beds deposited disconformably on the western facies assemblage. This disconformity, clearly exposed in 10 mountain ranges, indicates regional uplift and erosion of the western facies assemblage and absence of local deformation. The disconformity represents the Antler orogeny.

Bacterial diversity in Fe-rich hydrothermal sediments at two South Tonga Arc submarine volcanoes.

PubMed

Forget, N L; Murdock, S A; Juniper, S K

2010-12-01

Seafloor iron oxide deposits are a common feature of submarine hydrothermal systems. Morphological study of these deposits has led investigators to suggest a microbiological role in their formation, through the oxidation of reduced Fe in hydrothermal fluids. Fe-oxidizing bacteria, including the recently described Zetaproteobacteria, have been isolated from a few of these deposits but generally little is known about the microbial diversity associated with this habitat. In this study, we characterized bacterial diversity in two Fe oxide samples collected on the seafloor of Volcanoes 1 and 19 on the South Tonga Arc. We were particularly interested in confirming the presence of Zetaproteobacteria at these two sites and in documenting the diversity of groups other than Fe oxidizers. Our results (small subunit rRNA gene sequence data) showed a surprisingly high bacterial diversity, with 150 operational taxonomic units belonging to 19 distinct taxonomic groups. Both samples were dominated by Zetaproteobacteria Fe oxidizers. This group was most abundant at Volcano 1, where sediments were richer in Fe and contained more crystalline forms of Fe oxides. Other groups of bacteria found at these two sites include known S- and a few N-metabolizing bacteria, all ubiquitous in marine environments. The low similarity of our clones with the GenBank database suggests that new species and perhaps new families were recovered. The results of this study suggest that Fe-rich hydrothermal sediments, while dominated by Fe oxidizers, can be exploited by a variety of autotrophic and heterotrophic micro-organisms. © 2010 Blackwell Publishing Ltd.

The late Cenozoic diatom stratigraphy and paleolimnology of Tule Lake, Siskiyou Co. California

USGS Publications Warehouse

Bradbury, J.P.

1991-01-01

Lacustrine diatoms are diverse, well preserved and abundant in cores of lake sediment to 334 m depth near the town of Tulelake, Siskiyou County, northern California. The cores have been dated by radiometric, tephrochronologic and paleomagnetic techniques, which indicate a basal age of about 3 million years (Ma) and a nearly continuous depositional record for the Tule Lake basin for the last 3 million years (My). Fossil diatoms document the late Cenozoic paleolimnologic and paleoclimatic history for the northwestern edge of the Basin and Range Province. During the last 3 My, Tule Lake was typically a relatively deep, extensive lake. The Pliocene is characterized by a diatom flora dominated by Aulacoseira solida suggesting more abundant summer precipitation and warmer winters. Increases in 'Fragilaria' at 2.4 Ma and between 2.0 and 1.7 Ma imply cooler summers that correlate to glacial environments recorded elsewhere in the world. Stephanodiscus niagarae and 'Fragilaria' species dominate the Pleistocene. Benthic diatoms of alkalineenriched, saline waters occur with S. niagarae between 100 and 40 m depth (0.90-0.14 Ma). Tephrochronology indicates slow deposition and possible hiatuses between about 0.6 and 0.2 Ma. Overall, the Pleistocene diatom flora reflects cooler and sometimes drier climates, especially after major glaciations began 0.85 Ma. The chronology of even-numbered oxygen isotope stages approximately matches fluctuations in the abundance in 'Fragilaria' species since 1 Ma, suggesting that glacial periods at Tule Lake were expressed by relatively cool summers with enhanced effective moisture. Interglacial periods are represented by variable mixtures of freshwater planktonic and benthic alkaline diatom assemblages that suggest seasonal environments with winter-spring precipitation and summer moisture deficits. Glacial-interglacial environments since 150 ka were distinct from, and more variable than, those occurring earlier. The last full glacial period was very dry. Aulacoseira ambigua characterizes the late glacial and early Holocene record of Tule Lake. Its distribution indicates that warmer and wetter climates began about 15 ka in this part of the Great Basin. Fluctuations in diatom concentration suggests a 41000-yr. cycle between 3.0 and 2.5 Ma and 100000-yr. cycles after 1.0 Ma. In the late Pliocene and early Pleistocene, Aulacoseira solida percentages wax and wane in an approximately 400000-yr. cycle. The apparent response of Tule Lake diatom communities to orbitally induced insolation cycles underscores the importance of this record for the study of late Cenozoic paleoclimate change. The diatom stratigraphy records the evolution and local extinction of several species that may be biochronologically important. Stephanodiscus niagarae first appeared and became common in the Tule Lake record shortly after 1.8 Ma. Stephanodiscus carconensis disappeared about 1.8 Ma, while Aulacoseira solida is rare in the core after about 1.35 Ma. Cyclotella elgeri, a diatom characteristic of some outcrops referred to the Yonna Formation (Pliocene), is common only near the base of the core at an age of about 3 Ma. Detection of local extinctions is complicated by reworking of distinctive species from Pliocene diatomites surrounding Tule Lake. A new species, Aulacoseira paucistriata, is described from Pliocene lake deposits in the Klamath Basin. ?? 1991 Kluwer Academic Publishers.

Magmatic-vapor expansion and the formation of high-sulfidation gold deposits: Chemical controls on alteration and mineralization

USGS Publications Warehouse

Henley, R.W.; Berger, B.R.

2011-01-01

Large bulk-tonnage high-sulfidation gold deposits, such as Yanacocha, Peru, are the surface expression of structurally-controlled lode gold deposits, such as El Indio, Chile. Both formed in active andesite-dacite volcanic terranes. Fluid inclusion, stable isotope and geologic data show that lode deposits formed within 1500. m of the paleo-surface as a consequence of the expansion of low-salinity, low-density magmatic vapor with very limited, if any, groundwater mixing. They are characterized by an initial 'Sulfate' Stage of advanced argillic wallrock alteration ?? alunite commonly with intense silicification followed by a 'Sulfide' Stage - a succession of discrete sulfide-sulfosalt veins that may be ore grade in gold and silver. Fluid inclusions in quartz formed during wallrock alteration have homogenization temperatures between 100 and over 500 ??C and preserve a record of a vapor-rich environment. Recent data for El Indio and similar deposits show that at the commencement of the Sulfide Stage, 'condensation' of Cu-As-S sulfosalt melts with trace concentrations of Sb, Te, Bi, Ag and Au occurred at > 600 ??C following pyrite deposition. Euhedral quartz crystals were simultaneously deposited from the vapor phase during crystallization of the vapor-saturated melt occurs to Fe-tennantite with progressive non-equilibrium fractionation of heavy metals between melt-vapor and solid. Vugs containing a range of sulfides, sulfosalts and gold record the changing composition of the vapor. Published fluid inclusion and mineralogical data are reviewed in the context of geological relationships to establish boundary conditions through which to trace the expansion of magmatic vapor from source to surface and consequent alteration and mineralization. Initially heat loss from the vapor is high resulting in the formation of acid condensate permeating through the wallrock. This Sulfate Stage alteration effectively isolates the expansion of magmatic vapor in subsurface fracture arrays from any external contemporary hydrothermal activity. Subsequent fracturing is localized by the embrittled wallrock to provide high-permeability fracture arrays that constrain vapor expansion with minimization of heat loss. The Sulfide Stage vein sequence is then a consequence of destabilization of metal-vapor species in response to depressurization and decrease in vapor density. The geology, mineralogy, fluid inclusion and stable isotope data and geothermometry for high-sulfidation, bulk-tonnage and lode deposits are quite different from those for epithermal gold-silver deposits such as McLaughlin, California that formed near-surface in groundwater-dominated hydrothermal systems where magmatic fluid has been diluted to less than about 30%. High sulfidation gold deposits are better termed 'Solfataric Gold Deposits' to emphasize this distinction. The magmatic-vapor expansion hypothesis also applies to the phenomenology of acidic geothermal systems in active volcanic systems and equivalent magmatic-vapor discharges on the flanks of submarine volcanoes. ?? 2010.

Geology and geochemistry of Summitville, Colorado: an epithermal acid sulfate deposit in a volcanic dome

USGS Publications Warehouse

Gray, J.E.; Coolbaugh, M.F.

1994-01-01

Geologic studies during recent open-pit mining at Summitville, Colorado, have provided new information on an epithermal acid sulfate Au-Ag-Cu deposit formed in a volcanic dome. Geologic mapping, geochemical studies of whole-rock samples from blast holes, and geologic and geochemical traverse studies refine the details of the evolution of the Summitville deposit. Six distinct events followed emplacement of the quartz latite volcanic dome and define the development of the Summitville deposit: 1) an early stage of acid sulfate alteration, 2) subsequent Cu sulfide and gold mineralization, 3) widespread hydrothermal brecciation, 4) volumetrically minor, base metal sulfide-bearing barite veining, 5) volumetrically minor, kaolinite matrix brecciation, and finally, 6) supergene oxidation. -from Authors

Defining the physiologically normal coating and pathological deposit: an analysis of sulfur-containing moieties and pellicle thickness on hydrogel contact lenses.

PubMed

Hart, D E; Plociniak, M P; Grimes, G W

1998-04-01

Historically, biochemical studies of the interaction between tears and hydrogel contact lenses have not been coordinated with the study of the morphological ultrastructure of the phenomena. Moreover, terms that have distinct and different meanings--pellicle, coating, deposit, and biofilm--have been used interchangeably and often incorrectly when applied within the context of the general field of contact lens biotechnology to describe the tear-polymer interaction. We describe our elucidation of morphological and elemental characteristics of the normal pellicle that forms on the lens surface and urge standard use of the word "pellicle" to specify this entity. Fourteen worn hydrogel lenses (8 Group 1 and 6 Group 4 lenses according to the FDA classification) were rinsed, quartered, and fixed or dried, depending on the analysis to be performed. Scanning electron microscopy (SEM) was used to examine the morphology of the pellicle and quantify its thickness. X-ray analysis was used to detect elements associated with the anterior, central, and posterior portions of the lenses and their relative distribution. A distinctive morphological pellicle ranging from 0.1 to 8.6 microns was present on 12 of the 14 lenses. The pellicle was thicker on the Group 4 lenses than on the Group 1 lenses (P < 0.003). However, the pellicle on Group 1 lenses became thicker with increasing lens age (P < 0.02), but not as thick as on Group 4 lenses. Morphologically distinct lipid or jelly bump deposits were observed at the surface of both lenses from a single patient wearing 2 week old Group 4 lenses. Eleven lenses had sulfur-bearing tear components on the anterior zone. Sulfur was deposited within the matrix of nine lenses. The sulfur containing moieties were more prevalent on Group 4 lenses (P < 0.002). More sulfur was assayed on older lenses (P < 0.004). The anterior lens zone had more sulfur-bearing tear components than did the posterior or center zones (P < 0.05). The physiologically normal pellicle is a distinct morphological entity covering the anterior lens surface. Abnormal deposits such as the discrete microgel region, known as jelly bumps, are not part of the physiologically normal pellicle at the anterior lens surface and have the potential to induce pathology. Sulfur-containing moieties within the matrix may represent the breakdown of large proteins and mucoproteins or intact proteins, as well as contaminants such as cosmetics and environmental pollutants. It is also possible that entire small proteins, such as lysozyme, impregnate the matrix. The moieties that become entrapped within the matrix or rigidly adhere to the matrix should be considered true deposits.

Composition and Formation of the "Paso Robles" Class Soils at Gusev Crater

NASA Technical Reports Server (NTRS)

Yen, A. S.; Morris, Richard V.; Gellert, R.; Clark, B. C.; Ming, Douglas W.; Klingelhoefer, G.; McCoy, T. J.; Schmidt, M. E.

2007-01-01

Light-toned, subsurface soil deposits have been excavated by the Mars Exploration Rover (MER) Spirit in six distinct locations along its traverse across the Columbia Hills of Gusev Crater. Samples at two of these sites have been analyzed in detail by the M ssbauer (MB) and Alpha Particle X-ray Spectrometers (APXS), providing information on iron mineralogy and elemental chemistry, respectively. These soils are referred to as "Paso Robles" class deposits.

Middle Pleistocene infill of Hinkley Valley by Mojave River sediment and associated lake sediment: Depositional architecture and deformation by strike-slip faults

USGS Publications Warehouse

Miller, David; Haddon, Elizabeth; Langenheim, Victoria; Cyr, Andrew J.; Wan, Elmira; Walkup, Laura; Starratt, Scott W.

2018-01-01

Hinkley Valley in the Mojave Desert, near Barstow about 140 km northeast of Los Angeles and midway between Victorville Valley and the Lake Manix basin, contains a thick sedimentary sequence delivered by the Mojave River. Our study of sediment cores drilled in the valley indicates that Hinkley Valley was probably a closed playa basin with stream inflow from four directions prior to Mojave River inflow. The Mojave River deposited thick and laterally extensive clastic wedges originating from the southern valley that rapidly filled much of Hinkley Valley. Sedimentary facies representing braided stream, wetland, delta, and lacustrine depositional environments all are found in the basin fill; in some places, the sequence is greater than 74 m (245 ft) thick. The sediment is dated in part by the presence of the ~631 ka Lava Creek B ash bed low in the section, and thus represents sediment deposition after Victorville basin was overtopped by sediment and before the Manix basin began to be filled. Evidently, upstream Victorville basin filled with sediment by about 650 ka, causing the ancestral Mojave River to spill to the Harper and Hinkley basins, and later to Manix basin.Initial river sediment overran wetland deposits in many places in southern Hinkley Valley, indicating a rapidly encroaching river system. These sediments were succeeded by a widespread lake (“blue” clay) that includes the Lava Creek B ash bed. Above the lake sediment lies a thick section of interlayered stream sediment, delta and nearshore lake sediment, mudflat and/or playa sediment, and minor lake sediment. This stratigraphic architecture is found throughout the valley, and positions of lake sediment layers indicate a successive northward progression in the closed basin. A thin overlapping sequence at the north end of the valley contains evidence for a younger late Pleistocene lake episode. This late lake episode, and bracketing braided stream deposits of the Mojave River, indicate that the river avulsed through the valley, rather than continuing toward Lake Manix, during the late Pleistocene. Two dextral strike-slip fault zones, the Lockhart and the Mt. General, fold and displace the distinctive stratigraphic units, as well as surficial late Pleistocene and Holocene deposits. The sedimentary architecture and the two fault zones provide a framework for evaluating groundwater flow in Hinkley Valley.

Proposal for MSW contaminant classification applied to a tropical aquifer.

PubMed

de Faria, Gabriel Messias Moura; Mondelli, Giulliana

2018-04-01

Groundwater is a natural resource exploited worldwide causing danger due to the lixiviation of waste deposited, which presents high potential degradation. Internationally, regulation aims for the maintenance of the quality of this resource. But the local lithology, mainly in countries with tropical weather, was not considered. This paper has an objective to propose two methodologies of contaminant identification of municipal solid waste (MSW) considering the Brazilian regulation, the local lithology and the temporal aspect. The study site is located in the midwest of São Paulo, at the Marília Formation, Bauru Aquifer, which presents sandstone rich in calcite. At first, the historic monitoring data accumulated between 2002 and 2015 were statistically organized. Then, methodologies of classification of major constituents and contamination method were developed. After these analyses, the compounds that possibly cause anomaly in the local environment are Al, As, Ba, Ca, Cd, Co, Cr, Cu, phosphatic, nitrogenous, and sulfated compounds, Fe, K, Mn, Ni, and Pb. Some of these have lithogenic genesis typical of tropical environment, and others come from the disposed waste. Despite different approaches, both methods demonstrate efficiency in identifying the pollutants presenting distinctions among themselves in conjunction with actual local regulation and the lithogenic source of certain compounds.

The functional significance of the spinose keel structure of benthic foraminifera: inferences from Miliolina cristata Millett, 1898 (Miliolida) from northeast Romania

NASA Astrophysics Data System (ADS)

Dumitriţa Dumitriu, Simina; Dubicka, Zofia; Ionesi, Viorel

2018-01-01

The paper presents Miocene (lower Sarmatian) benthic foraminifera from the FH3P1 Rădăuţi Core section from the northwestern part of the Moldavian Platform, Romania. Based on foraminiferal assemblages we infer sediments were deposited in shallow-water, including marine-marginal environments, of varying salinities from brackish to normal marine with some short and rather small sea-level changes. Moreover, we describe for the first time in the Moldavian Platform a very rare species, Miliolina cristata Millett, which presents a characteristic spinose keel. Based on a detailed study of the test morphology and its variability, observed in picked material as well as in thin sections, we discuss some palaeoecological aspects of these foraminifera. M. cristata probably does not constitute a distinctive species, but it is more probable that some miliolid taxa developed such an exoskeletal feature in response to new environmental conditions, such as more turbulent water. Accordingly, our study would support the thesis that one of the functions of the benthic foraminiferal spines is to stabilize foraminiferal tests found in sandy substrates from high-energy environments.

Diatoms as Proxies for a Fluctuating Ice Cap Margin, Hvitarvatn, Iceland

NASA Astrophysics Data System (ADS)

Black, J. L.; Miller, G. H.; Geirsdottir, A.

2005-12-01

There are no complete records of terrestrial environmental change for the Holocene (11,000yrs) in Iceland and the status of Icelandic glaciers in the early Holocene remains unclear. It is not even known whether Iceland's large ice caps disappeared in the early Holocene, and if they did, when they re-grew. Icelandic lakes are particularly well suited to address these uncertainties as: 1) Glacial erosion and soft bedrock result in high lacustrine sedimentation rates, 2) Diagnostic tephras aid the geochronology, 3) Iceland's sensitivity to changes in North Atlantic circulation should produce clear signals in key environmental proxies (diatoms) preserved in lacustrine sequences, and 4) Ice-cap profiles are relatively flat so small changes in the equilibrium line altitude result in large changes in accumulation area. Hence, large changes in ice-sheet margins during the Holocene will impact sedimentation in glacier-dominated lakes and the diatom assemblages at those times. Hvitarvatn is a glacier dominated lake located on the eastern margin of Langjokull Ice Cap in central-western Iceland. The uppermost Hvitarvatn sediments reflect a glacially dominated system with planktonic, silica-demanding diatom taxa that suggest a high dissolved silica and turbid water environment consistent with high fluxes of glacial flour. Below this are Neoglacial sediments deposited when Langjokull was active, but outlet glaciers were not in contact with Hvitarvatn. The diatom assemblage here shows a small increase in abundance, but is still dominated by planktic, silica-demanding taxa. A distinct shift in lake conditions is reflected in the lowermost sediments, composed of predominantly benthic diatoms and deposited in clear water conditions with long growing seasons likely found in an environment with warmer summers than present and with no glacial erosion. Langjokull must have disappeared in the early Holocene for such a diverse, benthic dominated diatom assemblage to flourish.

Remote sensing of Northern mines: supporting operation and environmental monitoring in cold conditions

NASA Astrophysics Data System (ADS)

Tuomela, Anne; Davids, Corine; Knutsson, Sven; Knutsson, Roger; Rauhala, Anssi; Rossi, Pekka M.; Rouyet, Line

2017-04-01

Northern areas of Finland, Sweden and Norway have mineral-rich deposits. There are several active mines in the area but also closed ones and deposits with plans for future mining. With increasing demand for environmental protection in the sensitive Northern conditions, there is a need for more comprehensive monitoring of the mining environment. In our study, we aim to develop new opportunities to use remote sensing data from satellites and unmanned aerial vehicles (UAVs) in improving mining safety and monitoring, for example in the case of mine waste storage facilities. Remote sensing methods have evolved fast, and could in many cases enable precise, reliable, and cost-efficient data collection over large areas. The study has focused on four mining areas in Northern Fennoscandia. Freely available medium-resolution (e.g. Sentinel-1), commercial high-resolution (e.g. TerraSAR-X) and Synthetic Aperture Radar (SAR) data has been collected during 2015-2016 to study how satellite remote sensing could be used e.g. for displacement monitoring using SAR Interferometry (InSAR). Furthermore, UAVs have been utilized in similar data collection in a local scale, and also in collection of thermal infrared data for hydrological monitoring of the areas. The development and efficient use of the methods in mining areas requires experts from several fields. In addition, the Northern conditions with four distinct seasons bring their own challenges for the efficient use of remote sensing, and further complicate their integration as standardised monitoring methods for mine environments. Based on the initial results, remote sensing could especially enhance the monitoring of large-scale structures in mine areas such as tailings impoundments.

South Atlantic sag basins: new petroleum system components

DOE Office of Scientific and Technical Information (OSTI.GOV)

Henry, S.G.; Mello, M.R.

Newly discovered pre-salt source rocks, reservoirs and seals need to be included as components to the petroleum systems of both sides of the South Atlantic. These new components lie between the pre-salt rift strata and the Aptian salt layers, forming large, post-rift, thermal subsidence sag basins. These are differentiated from the older rift basins by the lack of syn-rift faulting and a reflector geometry that is parallel to the base salt regional unconformity rather than to the Precambrian basement. These basins are observed in deep water regions overlying areas where both the mantle and the crust have been involved inmore » the extension. This mantle involvement creates post-rift subsiding depocenters in which deposition is continuous while proximal rift-phase troughs with little or no mantle involvement are bypassed and failed to accumulate potential source rocks during anoxic times. These features have been recognized in both West African Kwanza Basin and in the East Brasil Rift systems. The pre-salt source rocks that are in the West African sag basins were deposited in lacustrine brackish to saline water environment and are geochemically distinct from the older, syn-rift fresh to brackish water lakes, as well as from younger, post-salt marine anoxic environments of the drift phase. Geochemical analyses of the source rocks and their oils have shown a developing source rock system evolving from isolated deep rift lakes to shallow saline lakes, and culminating with the infill of the sag basin by large saline lakes to a marginally marine restricted gulf. Sag basin source rocks may be important in the South Atlantic petroleum system by charging deep-water prospects where syn-rift source rocks are overmature and the post-salt sequences are immature.« less

Devonian Terrestrial Revolution: the palaeoenvironment of the oldest known tetrapod tracks, Zachełmie Quarry, Poland

NASA Astrophysics Data System (ADS)

Niedźwiedzki, G.

2012-04-01

Numerous trackways and isolated prints with digit impressions, which are similar to the foot anatomy of early tetrapods such as Ichthyostega, were found on the three dolomite bed-surfaces in the lower part of the Wojciechowice Formation exposed in the Zachełmie Quarry in the Holy Cross Mountains (south-central Poland), (Niedźwiedzki et al., 2010). The age of the tetrapod track-bearing strata is well-constrained, but the detailed sedimentology of the lower section with tetrapod ichnites is still under study. The Wojciechowice Formation represent one of the first carbonate stages of a transgressive succession that begins with Early Devonian continental to marginal marine clastics and culminates in the development of a Givetian coral-stromatoporoid carbonate platform. The tetrapod track-bearing complex is composed of grey to reddish, thin- to medium-bedded dolomitic shales and marly dolomite mudstones. These deposits from the tetrapod track-bearing horizon lack definitive marine body fossils, and may have formed in a marginal marine environment, e.g. around a coastal lagoon. Mudcracks, columnar peds, root traces, and microbially induced sedimentary structures were found in three distinct pedotypes of very weakly to weakly developed paleosols (Retallack, 2011). Conodonts of the costatus zone (mid-Eifelian) were found 20 m above the uppermost surface with tetrapod tracks in limestones of the upper Wojciechowice Formation, which contain also brachiopod and crinoidal debris. The overlying Kowala Formation is a marine coral limestone and dolostone. The parts of profile with tetrapod ichnites and invertebrate and conodont fossils contain also records of invertebrate traces. Seven ichnotaxa are distributed among four recognized ichnoassemblages. The recognized ichnocoenoses are typical for the shallow-marine (Cruziana ichnofacies) and land-water transitional (Skolithos/Psilonichnus ichnofacies) carbonate depositional environments. The ichnocoenoses are dominated by trace fossils produced by arthropods (probably crustaceans), a group that can create large and distinctive burrows. The palaeoecological information from the Zachełmie section has direct bearing on the interpretation of environmental aspects of tetrapod emergence and terrestrialization. It should be fully integrated with data from other Devonian tetrapod tracksites. Niedźwiedzki, G., Szrek P., Narkiewicz K., Narkiewicz M. and Ahlberg P.E. 2010. Tetrapod trackways from the early Middle Devonian period of Poland. Nature, 463: 43-48. Retallack, G.J. 2011. Woodland Hypothesis for Devonian Tetrapod Evolution. The Journal of Geology, 119, 3: 235-258

Experimental verification of vapor deposition rate theory in high velocity burner rigs

NASA Technical Reports Server (NTRS)

Gokoglu, Suleyman A.; Santoro, Gilbert J.

1985-01-01

The main objective has been the experimental verification of the corrosive vapor deposition theory in high-temperature, high-velocity environments. Towards this end a Mach 0.3 burner-rig appartus was built to measure deposition rates from salt-seeded (mostly Na salts) combustion gases on the internally cooled cylindrical collector. Deposition experiments are underway.

Provenance of Des Moines lobe till records ice-stream catchment evolution during Laurentide deglaciation

USGS Publications Warehouse

Lusardi, B.A.; Jennings, C.E.; Harris, K.L.

2011-01-01

Mapping and analysis of deposits of the Des Moines lobe of the Laurentide Ice Sheet, active after the Last Glacial Maximum (LGM), reveal several texturally and lithologically distinct tills within what had been considered to be a homogeneous deposit. Although the differences between tills are subtle, minor distinctions are predictable and mappable, and till sheets within the area covered by the lobe can be correlated for hundreds of kilometres parallel to ice flow. Lateral till-sheet contacts are abrupt or overlap in a narrow zone, coincident with a geomorphic discontinuity interpreted to be a shear margin. Till sheets 10 to 20m thick show mixing in their lower 2 to 3m. We suggest that: (i) lithologically distinct till sheets correspond to unique ice-stream source areas; (ii) the sequence of tills deposited by the Des Moines lobe was the result of the evolution and varying dominance of nearby and competing ice streams and their tributaries; and (iii) in at least one instance, more than one ice stream simultaneously contributed to the lobe. Therefore the complex sequence of tills of subtly different provenances, and the unconformities between them record the evolution of an ice-catchment area during Laurentide Ice Sheet drawdown. Till provenance data suggest that, after till is created in the ice-stream source area, the subglacial conditions required for transporting till decline and incorporation of new material is limited. ?? 2011 The Authors. Boreas ?? 2011 The Boreas Collegium.

Bearing-Foreign Material Deposition on Retrieved Co-Cr Femoral Heads: Composition and Morphology

PubMed Central

Tikekar, Nishant M.; Heiner, Anneliese D.; Baer, Thomas E.; Kruger, Karen M.; Callaghan, John J.; Brown, Thomas D.; Lannutti, John J.

2015-01-01

Bearing-foreign material deposition onto a femoral head can occur from contact with an acetabular shell due to dislocation, reduction, or subluxation. The purpose of this study was to comprehensively characterize deposit regions on retrieved cobalt-chrome femoral heads from metal-on-polyethylene total hip arthroplasties that had experienced such adverse events. The morphology, topography, and composition of deposition regions were characterized using macrophotography, optical profilometry, scanning electron microscopy, energy dispersive spectroscopy, and X-ray photoelectron spectroscopy. The deposit areas were relatively large, they were much rougher than the surrounding undamaged clean areas, and they displayed several distinct morphologies. Titanium alloy elements were the predominant constituents. Calcium and phosphorous were also detected within the deposit areas, in a composition that could nucleate abrasive hydroxyapatite. In addition, tungsten-rich particles, likely present as tungsten carbide, were observed on top of the titanium deposits. The increased roughness associated with these deposition features would be expected to accelerate damage and wear of the opposing liner and hence accelerate the development of osteolysis. PMID:26236744

Comprehensive geobiological characterization of a bituminous carbonate facies with Ediacara-type fossils (Shibantan Member, South China)

NASA Astrophysics Data System (ADS)

Duda, Jan-Peter; Blumenberg, Martin; Thiel, Volker; Simon, Klaus; Zhu, Maoyan; Reitner, Joachim

2015-04-01

The Shibantan Member (Dengying Formation, Ediacaran Period) is one of only few carbonate settings with Ediacara-type fossils worldwide (e.g. Ding & Chen, 1981; Sun, 1986; Xiao et al., 2005; Shen et al., 2009; Chen et al., 2014). However, only little is known about the sedimentology and biogeochemistry of the environments in which these organisms throve. Here we provide a comprehensive geobiological characterization of the Shibantan Member, addressing the interplay between sedimentary and (bio-) geochemical processes. Sedimentary analysis revealed that black laminated limestones of the lower Shibantan Member were deposited after a sudden local deepening in a subtidal lower- to middle ramp environment close to the storm wave base, while the dark wavy dolomites of the upper Shibantan Member were deposited in a subtidal middle ramp environment between storm- and fair weather wave base. Sedimentation in the Shibantan basin was generally highly dynamic as evidenced by a distinct slumping horizon and mass-flow deposits that were possibly due to synsedimentary tectonic processes. The microbial-mat associated biota including Ediacara-type fossils is restricted to the lower Shibantan Member. Sedimentary analysis of this part reveals a close relationship between autochthonous mat growth and allochthonous and/or para-autochthonous event deposition. During deposition of the lower Shibantan Member the water column was probably temporarily stratified, with a sub- to anoxic water layer (evidenced by Ni/Co-, V/(V+Ni) and V/Sc ratios) overlain by a oxygenated upper layer (evidenced by negative Ce anomalies and low V/Cr ratios). However, such stratification was not permanent, as mixing by storm events is evidenced by hummocky cross stratification structures. 13C-enrichments in carbonates of the Lower Shibantan Member (δ13C = +3.3 to +4.0o VPDB) together with 13C-depletions of syngenetic n-alkanes cleaved from the respective extraction residue using catalytic hydropyrolysis (HyPy; δ13C = -31.7 to -36.3o VPDB) indicate a significant withdrawal of 12C by primary producers that thrived within the microbial mats. At the same time, sulphurised biomarkers in the bitumen and HyPy-treated extraction residue hint at organic matter decomposition and concomitant sulphide production by sulphate-reducing bacteria. Given the sedimentological evidence for periodical ventilation of the water column by storms, sulphide oxidising bacteria were possibly favoured whenever oxygen became available at the sediment-water interface. Taken together, the environments in which the microbial-mat-associated biota including Ediacara-type fossils throve were highly dynamic due to a complex interplay of geological and biological processes. References Chen Z., Zhou C., Xiao S., Wang W., Guan C., Hua H., Yuan X., 2014. New Ediacara fossils preserved in marine limestone and their ecological implications. Scientific Reports, 4 Ding Q. and Chen Y., 1981. Discovery of soft metazoan from the Sinian System along eastern Yangtze Gorge, Hubei. Journal of the Wuhan College of Geology, 2, 53-57. Shen, B., Xiao S., Zhou C., Yuan X., 2009. Yangtziramulus zhangi New Genus and Species, a Carbonate-Hosted Macrofossil from the Ediacaran Dengying Formation in the Yangtze Gorges Area, South China. Journal of Paleontology, 83(4): 575-587. Sun W., 1986. Late precambrian pennatulids (sea pens) from the eastern Yangtze Gorge, China: Paracharnia gen. nov. Precambrian Research, 31(4), 361-375. Xiao S., Shen B., Zhou C., Xie G., Yuan X., 2005. A uniquely preserved Ediacaran fossil with direct evidence for a quilted bodyplan. Proceedings of the National Academy of Sciences of the United States of America, 102(29), 10227-10232.

Spatially Resolved Genomic, Stable Isotopic, and Lipid Analyses of a Modern Freshwater Microbialite from Cuatro Ciénegas, Mexico

PubMed Central

Nitti, Anthony; Daniels, Camille A.; Siefert, Janet; Souza, Valeria; Hollander, David

2012-01-01

Abstract Microbialites are biologically mediated carbonate deposits found in diverse environments worldwide. To explore the organisms and processes involved in microbialite formation, this study integrated genomic, lipid, and both organic and inorganic stable isotopic analyses to examine five discrete depth horizons spanning the surface 25 mm of a modern freshwater microbialite from Cuatro Ciénegas, Mexico. Distinct bacterial communities and geochemical signatures were observed in each microbialite layer. Photoautotrophic organisms accounted for approximately 65% of the sequences in the surface community and produced biomass with distinctive lipid biomarker and isotopic (δ13C) signatures. This photoautotrophic biomass was efficiently degraded in the deeper layers by heterotrophic organisms, primarily sulfate-reducing proteobacteria. Two spatially distinct zones of carbonate precipitation were observed within the microbialite, with the first zone corresponding to the phototroph-dominated portion of the microbialite and the second zone associated with the presence of sulfate-reducing heterotrophs. The coupling of photoautotrophic production, heterotrophic decomposition, and remineralization of organic matter led to the incorporation of a characteristic biogenic signature into the inorganic CaCO3 matrix. Overall, spatially resolved multidisciplinary analyses of the microbialite enabled correlations to be made between the distribution of specific organisms, precipitation of carbonate, and preservation of unique lipid and isotopic geochemical signatures. These findings are critical for understanding the formation of modern microbialites and have implications for the interpretation of ancient microbialite records. Key Words: Microbial ecology—Microbe-mineral interactions—Microbial mats—Stromatolites—Genomics. Astrobiology 12, 685–698. PMID:22882001

Uranium mineralization and unconformities: how do they correlate? - A look beyond the classic unconformity-type deposit model?

NASA Astrophysics Data System (ADS)

Markwitz, Vanessa; Porwal, Alok; Campbell McCuaig, T.; Kreuzer, Oliver P.

2010-05-01

Uranium deposits are usually classified based on the characteristics of their host rocks and geological environments (Dahlkamp, 1993; OECD/NEA Red Book and IAEA, 2000; Cuney, 2009). The traditional unconformity-related deposit types are the most economical deposits in the world, with the highest grades amongst all uranium deposit types. In order to predict undiscovered uranium deposits, there is a need to understand the spatial association of uranium mineralization with structures and unconformities. Hydrothermal uranium deposits develop by uranium enriched fluids from source rocks, transported along permeable pathways to their depositional environment. Unconformities are not only separating competent from incompetent sequences, but provide the physico-chemical gradient in the depositional environment. They acted as important fluid flow pathways for uranium to migrate not only for surface-derived oxygenated fluids, but also for high oxidized metamorphic and magmatic fluids, dominated by their geological environment in which the unconformities occur. We have carried out comprehensive empirical spatial analyses of various types of uranium deposits in Australia, and first results indicate that there is a strong spatial correlation between unconformities and uranium deposits, not only for traditional unconformity-related deposits but also for other styles. As a start we analysed uranium deposits in Queensland and in particular Proterozoic metasomatic-related deposits in the Mount Isa Inlier and Late Carboniferous to Early Permian volcanic-hosted uranium occurrences in Georgetown and Charters Towers Regions show strong spatial associations with contemporary and older unconformities. The Georgetown Inlier in northern Queensland consists of a diverse range of rocks, including Proterozoic and early Palaeozoic metamorphic rocks and granites and late Palaeozoic volcanic rocks and related granites. Uranium-molybdenum (+/- fluorine) mineralization in the Georgetown inlier varies from strata- to structure-bound and occurs above regional unconformities. The Proterozoic basins in the Mount Isa Inlier rest unconformably on Palaeoproterozoic basement accompanied by volcanic and igneous rocks, which were deformed and metamorphosed in the Mesoproterozoic. Uranium occurrences in the Western Succession of Mount Isa are either hosted in clastic metasediments or mafic volcanics that belong to the Palaeoproterozoic Eastern Creek Volcanics. Uranium and vanadium mineralization occur in metasomatised and hematite-magnetite-carbonate alteration zones, bounded by major faults and regional unconformities. The results of this study highlight the importance of unconformities in uranium minerals systems as possible fluid pathways and/or surfaces of physico-chemical contrast that could have facilitated the precipitation of uranium, not only in classical unconformity style uranium deposits but in several other styles of uranium mineralization as well. References Cuney, M., 2009. The extreme diversity of uranium deposits. Mineralium Deposita, 44, 3-9. Dahlkamp, F. J., 1993. Uranium ore deposits. Springer, Berlin, p 460. OECD / NEA Red Book & IAEA, 2000. Uranium 1999: Resources, Production and Demand. OECD Nuclear Energy Agency and International Atomic Energy Agency, Paris.

Hydrothermal Evolution of the Giant Cenozoic Kadjaran porphyry Cu-Mo deposit, Tethyan metallogenic belt, Armenia, Lesser Caucasus: mineral paragenetic, cathodoluminescence and fluid inclusion constraints

NASA Astrophysics Data System (ADS)

Hovakimyan, Samvel; Moritz, Robert; Tayan, Rodrik; Rezeau, Hervé

2016-04-01

The Lesser Caucasus belongs to the Central segment of the Tethyan metallogenic belt and it is a key area to understand the metallogenic evolution between the Western & Central parts of the Tethyan belt and its extension into Iran. Zangezur is the most important mineral district in the southernmost Lesser Caucasus. It is a component of the South Armenian block, and it was generated during the convergence and collision of the southern margin of the Eurasian plate and the northern margin of the Arabian plate, and terranes of Gondwana origin (Moritz et al., in press). The Zangezur ore district consists of the Tertiary Meghri-Ordubad composite pluton, which is characterized by a long-lasting Eocene to Pliocene magmatic, tectonic and metallogenic evolution. It hosts major porphyries Cu-Mo and epithermal Au - polymetallic deposits and occurrences, including the giant world class Kadjaran porphyry Cu-Mo deposit (2244 Mt reserves, 0.3% Cu, 0.05% Mo and 0.02 g/t Au). The Kadjaran deposit is hosted by a monzonite intrusion (31.83±0.02Ma; Moritz et al., in press). Detailed field studies of the porphyry stockwork and veins of the different mineralization stages, their crosscutting and displacement relationships and the age relationship between different paragenetic mineral associations were the criteria for distinction of the main stages of porphyry mineralization at the Kadjaran deposit. The economic stages being: quartz- molybdenite, quartz-molybdenite-chalcopyrite, and quartz-chalcopyrite. The main paragenetic association of the Kadjaran porphyry deposit includes pyrite, molybdenite, chalcopyrite, bornite, chalcocite, pyrrhotite, covellite, sphalerite, and galena. Recent field observations in the Kadjaran open pit revealed the presence of epithermal veins with late vuggy silica and advanced argillic alteration in the north-eastern and eastern parts of the deposit. They are distributed as separate veins and have also been recognized in re-opened porphyry veins and in stockwork. One of them is the east-west-oriented 6th vein zone in the northern part of the deposit, which contains quartz-molybdenite veins and late quartz-galena-sphalerite veins. This is interpreted as a telescoping between porphyry and epithermal environments. It is supported by microscopic studies of mineral paragenesis, which reveal the presence of enargite and tennantite-tetrahedrite, luzonite, sphalerite, and galena, generally in a gangue of quartz, followed by a late carbonate and gypsum stage. On-going fluid inclusion studies are being carried out on quartz samples from the different mineralization stages. Five types of fluid inclusions were distinguished according to their nature, bubble size, and daughter mineral content: vapor-rich, aqueous-carbonic, brine, polyphase brine and liquid-rich inclusions. Cathodoluminescence images from the porphyry veins reveal four generations of quartz. Molybdenite and chalcopyrite are associated with two different dark luminescent quartz generations, which contain typical brine, aqueous-carbonic and vapour-rich H2O fluid inclusions, with some of them coexisting locally as boiling assemblages. Epithermal veins are mainly characterized by liquid-rich H2O fluid inclusions. Microthermometric studies of fluid inclusions reveal a major difference in homogenisation temperatures between the early quartz-molybdenite- chalcopyrite stage (Thtotal between 3600 and 4250C) and the late quartz-galena-sphalerite vein stage (Thtotal 300-2700C), which is attributed to the transition from a porphyry to an epithermal environment in the Kadjaran deposit.

A conceptual model for assessing the internal environment of a healthcare organization.

PubMed

Asubonteng, P

1997-01-01

By understanding the opportunities and threats in the external environment and relating them to the organization's internal strengths and weaknesses, strategic managers can determine the distinctive competence of the organization. Distinctive competence refers to the strengths that will give an organization a competitive advantage.

A radon progeny deposition model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rielage, Keith; Elliott, Steven R; Hime, Andrew

2010-12-01

The next generation low-background detectors operating underground aim for unprecedented low levels of radioactive backgrounds. Although the radioactive decays of airborne radon (particularly {sup 222}Rn) and its subsequent progeny present in an experiment are potential backgrounds, also problematic is the deposition of radon progeny on detector materials. Exposure to radon at any stage of assembly of an experiment can result in surface contamination by progeny supported by the long half life (22 y) of {sup 210}Pb on sensitive locations of a detector. An understanding of the potential surface contamination from deposition will enable requirements of radon-reduced air and clean roommore » environments for the assembly of low background experiments. It is known that there are a number of environmental factors that govern the deposition of progeny onto surfaces. However, existing models have not explored the impact of some environmental factors important for low background experiments. A test stand has been constructed to deposit radon progeny on various surfaces under a controlled environment in order to develop a deposition model. Results from this test stand and the resulting deposition model are presented.« less

Stratigraphy, facies analysis and depositional environments of the Upper Unit of Abu Roash "E" member in the Abu Gharadig field, Western Desert, Egypt

NASA Astrophysics Data System (ADS)

Hewaidy, Abdel Galil; Elshahat, O. R.; Kamal, Samy

2018-03-01

Abu Roach "E" member is of an important hydrocarbon reservoir-producing horizon in the Abu Gharadig Field (north Western Desert, Egypt). This study is used to build facies analysis and depositional environments model for the Upper Unit of the Abu Roash "E" member in Abu Gharadig Field. This target has been achieved throughout the sedimentological, wire line logs, lithostratigraphic and biostratigraphic analyses of more than 528 feet cores. The high-resolution biostratigraphic analysis provides a calibration for the paleo-bathymetry and depositional environmental interpretations. Biozonation and lithostratigraphic markers are used to constrain stratigraphic correlation. Integration between the core description and petorographic microfacies analysis by microscope examination provide an excellent indication for the rock types and depositional environments. Five depositional facies types are detected including carbonate inner ramp, tidal flats, tidal channels, supra-tidal and tide dominated delta facies. This model helps in the understanding of the Upper Unit of Abu Roash "E" member reservoir distribution as well as lateral and vertical facies changes that contribute to the development strategy for the remaining hydrocarbon reserves for this important oil reservoir.

Ants adjust their pheromone deposition to a changing environment and their probability of making errors

PubMed Central

Czaczkes, Tomer J.; Heinze, Jürgen

2015-01-01

Animals must contend with an ever-changing environment. Social animals, especially eusocial insects such as ants and bees, rely heavily on communication for their success. However, in a changing environment, communicated information can become rapidly outdated. This is a particular problem for pheromone trail using ants, as once deposited pheromones cannot be removed. Here, we study the response of ant foragers to an environmental change. Ants were trained to one feeder location, and the feeder was then moved to a different location. We found that ants responded to an environmental change by strongly upregulating pheromone deposition immediately after experiencing the change. This may help maintain the colony's foraging flexibility, and allow multiple food locations to be exploited simultaneously. Our treatment also caused uncertainty in the foragers, by making their memories less reliable. Ants which had made an error but eventually found the food source upregulated pheromone deposition when returning to the nest. Intriguingly, ants on their way towards the food source downregulated pheromone deposition if they were going to make an error. This may suggest that individual ants can measure the reliability of their own memories and respond appropriately. PMID:26063845

Paleoclimatological analysis of Late Eocene core, Manning Formation, Brazos County, Texas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yancey, T.; Elsik, W.

1994-09-01

A core of the basal part of the Manning Formation was drilled to provide a baseline for paleoclimate analysis of the expanded section of siliciclastic sediments of late Eocene age in the outcrop belt. The interdeltaic Jackson Stage deposits of this area include 20+ cyclic units containing both lignite and shallow marine sediments. Depositional environments can be determined with precision and the repetitive nature of cycles allows comparisons of the same environment throughout, effectively removing depositional environment as a variable in interpretation of climate signal. Underlying Yegua strata contain similar cycles, providing 35+ equivalent environmental transacts within a 6 m.y.more » time interval of Jackson and Yegua section, when additional cores are taken. The core is from a cycle deposited during maximum flooding of the Jackson Stage, with deposits ranging from shoreface (carbonaceous) to midshelf, beyond the range of storm sand deposition. Sediments are leached of carbonate, but contain foram test linings, agglutinated forams, fish debris, and rich assemblages of terrestrial and marine palynomorphs. All samples examined contain marine dinoflagellates, which are most abundant in transgressive and maximum flood zones, along with agglutinated forams and fish debris. This same interval contains two separate pulses of reworked palynomorphs. The transgressive interval contains Glaphyrocysta intricata, normally present in Yegua sediments. Pollen indicates fluctuating subtropical to tropical paleoclimates, with three short cycles of cooler temperatures, indicated by abundance peaks of alder pollen (Alnus) in transgressive, maximum flood, and highstand deposits.« less

Grain size statistics and depositional pattern of the Ecca Group sandstones, Karoo Supergroup in the Eastern Cape Province, South Africa

NASA Astrophysics Data System (ADS)

Baiyegunhi, Christopher; Liu, Kuiwu; Gwavava, Oswald

2017-11-01

Grain size analysis is a vital sedimentological tool used to unravel the hydrodynamic conditions, mode of transportation and deposition of detrital sediments. In this study, detailed grain-size analysis was carried out on thirty-five sandstone samples from the Ecca Group in the Eastern Cape Province of South Africa. Grain-size statistical parameters, bivariate analysis, linear discriminate functions, Passega diagrams and log-probability curves were used to reveal the depositional processes, sedimentation mechanisms, hydrodynamic energy conditions and to discriminate different depositional environments. The grain-size parameters show that most of the sandstones are very fine to fine grained, moderately well sorted, mostly near-symmetrical and mesokurtic in nature. The abundance of very fine to fine grained sandstones indicate the dominance of low energy environment. The bivariate plots show that the samples are mostly grouped, except for the Prince Albert samples that show scattered trend, which is due to the either mixture of two modes in equal proportion in bimodal sediments or good sorting in unimodal sediments. The linear discriminant function analysis is dominantly indicative of turbidity current deposits under shallow marine environments for samples from the Prince Albert, Collingham and Ripon Formations, while those samples from the Fort Brown Formation are lacustrine or deltaic deposits. The C-M plots indicated that the sediments were deposited mainly by suspension and saltation, and graded suspension. Visher diagrams show that saltation is the major process of transportation, followed by suspension.

FAST TRACK COMMUNICATION Understanding adhesion at as-deposited interfaces from ab initio thermodynamics of deposition growth: thin-film alumina on titanium carbide

NASA Astrophysics Data System (ADS)

Rohrer, Jochen; Hyldgaard, Per

2010-12-01

We investigate the chemical composition and adhesion of chemical vapour deposited thin-film alumina on TiC using and extending a recently proposed nonequilibrium method of ab initio thermodynamics of deposition growth (AIT-DG) (Rohrer and Hyldgaard 2010 Phys. Rev. B 82 045415). A previous study of this system (Rohrer et al 2010 J. Phys.: Condens. Matter 22 015004) found that use of equilibrium thermodynamics leads to predictions of a non-binding TiC/alumina interface, despite its industrial use as a wear-resistant coating. This discrepancy between equilibrium theory and experiment is resolved by the AIT-DG method which predicts interfaces with strong adhesion. The AIT-DG method combines density functional theory calculations, rate-equation modelling of the pressure evolution of the deposition environment and thermochemical data. The AIT-DG method was previously used to predict prevalent terminations of growing or as-deposited surfaces of binary materials. Here we extend the method to predict surface and interface compositions of growing or as-deposited thin films on a substrate and find that inclusion of the nonequilibrium deposition environment has important implications for the nature of buried interfaces.

Hydrothermal alteration of felsic volcanic rocks at the Helen Siderite Deposit, Wawa, Ontario

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morton, R.L.; Nebel, M.L.

1984-09-01

Felsic lavas and pyroclastic rocks, underlying the Archean Helen iron-formation, have been variably altered by hydrothermal solutions which, when discharged onto the sea floor, formed the Helen siderite deposit. Within the footwall volcanic sequence five chemically and mineralogically distinct alteration types have been defined: least altered, sericite, chlorite chloritoid, and ankerite. Based on mineralogy and chemistry of the altered rocks and on the geometry of the alteration zones, an alteration model is proposed.

Distinct contributions of complement factors to platelet activation and fibrin formation in venous thrombus development

PubMed Central

Jäckel, Sven; Saffarzadeh, Mona; Langer, Florian

2017-01-01

Expanding evidence indicates multiple interactions between the hemostatic system and innate immunity, and the coagulation and complement cascades. Here we show in a tissue factor (TF)–dependent model of flow restriction-induced venous thrombosis that complement factors make distinct contributions to platelet activation and fibrin deposition. Complement factor 3 (C3) deficiency causes prolonged bleeding, reduced thrombus incidence, thrombus size, fibrin and platelet deposition in the ligated inferior vena cava, and diminished platelet activation in vitro. Initial fibrin deposition at the vessel wall over 6 hours in this model was dependent on protein disulfide isomerase (PDI) and TF expression by myeloid cells, but did not require neutrophil extracellular trap formation involving peptidyl arginine deiminase 4. In contrast to C3−/− mice, C5-deficient mice had no apparent defect in platelet activation in vitro, and vessel wall platelet deposition and initial hemostasis in vivo. However, fibrin formation, the exposure of negatively charged phosphatidylserine (PS) on adherent leukocytes, and clot burden after 48 hours were significantly reduced in C5−/− mice compared with wild-type controls. These results delineate that C3 plays specific roles in platelet activation independent of formation of the terminal complement complex and provide in vivo evidence for contributions of complement-dependent membrane perturbations to prothrombotic TF activation on myeloid cells. PMID:28223279

Sedimentary architecture and depositional environment of Kudat Formation, Sabah, Malaysia

NASA Astrophysics Data System (ADS)

Ghaheri, Samira; Suhaili, Mohd; Sapari, Nasiman; Momeni, Mohammadsadegh

2017-12-01

Kudat Formation originated from deep marine environment. Three lithofacies association of deep marine turbidity channel was discovered in three Members of the Kudat Formation in Kudat Peninsula, Sabah, Malaysia. Turbidite and deep marine architecture elements was described based on detailed sedimentological studies. Four architecture elements were identified based on each facies association and their lithology properties and character: inner external levee that was formed by turbidity flows spill out from their confinement of channel belt; Lobes sheet that was formed during downslope debris flows associated with levee; Channel fill which sediments deposited from high to low density currents with different value of sediment concentration; and overbank terrace which was formed by rapid suspension sedimentation. The depositional environment of Kudat Formation is shelf to deep marine fan.

Sediment-Hosted Copper Deposits of the World: Deposit Models and Database

USGS Publications Warehouse

Cox, Dennis P.; Lindsey, David A.; Singer, Donald A.; Diggles, Michael F.

2003-01-01

Introduction This publication contains four descriptive models and four grade-tonnage models for sediment hosted copper deposits. Descriptive models are useful in exploration planning and resource assessment because they enable the user to identify deposits in the field and to identify areas on geologic and geophysical maps where deposits could occur. Grade and tonnage models are used in resource assessment to predict the likelihood of different combinations of grades and tonnages that could occur in undiscovered deposits in a specific area. They are also useful in exploration in deciding what deposit types meet the economic objectives of the exploration company. The models in this report supersede the sediment-hosted copper models in USGS Bulletin 1693 (Cox, 1986, and Mosier and others, 1986) and are subdivided into a general type and three subtypes. The general model is useful in classifying deposits whose features are obscured by metamorphism or are otherwise poorly described, and for assessing regions in which the geologic environments are poorly understood. The three subtypes are based on differences in deposit form and environments of deposition. These differences are described under subtypes in the general model. Deposit models are based on the descriptions of geologic environments and physical characteristics, and on metal grades and tonnages of many individual deposits. Data used in this study are presented in a database representing 785 deposits in nine continents. This database was derived partly from data published by Kirkham and others (1994) and from new information in recent publications. To facilitate the construction of grade and tonnage models, the information, presented by Kirkham in disaggregated form, was brought together to provide a single grade and a single tonnage for each deposit. Throughout the report individual deposits are defined as being more than 2,000 meters from the nearest adjacent deposit. The deposit models are presented here as a PDF file. The database can be most conveniently read in FileMaker Pro. For those who do not have the FileMaker application, Microsoft-Excel, tab-delimited-ASCII and comma-separated-value files are included. The reader may be interested in a similar publication on porphyry copper deposits (Singer and others, 2005) also available online. The Google Earth image is not intended to be viewed at the highest possible magnification because the resolution of the database is plus or minus two kilometers. At extreme zoom settings, the deposit locations may not coincide with the Google-Earth images of the mine workings.

A kinetic model for the characteristic surface morphologies of thin films by directional vapor deposition

NASA Astrophysics Data System (ADS)

Li, Kun-Dar; Huang, Po-Yu

2017-12-01

In order to simulate a process of directional vapor deposition, in this study, a numerical approach was applied to model the growth and evolution of surface morphologies for the crystallographic structures of thin films. The critical factors affecting the surface morphologies in a deposition process, such as the crystallographic symmetry, anisotropic interfacial energy, shadowing effect, and deposition rate, were all enclosed in the theoretical model. By altering the parameters of crystallographic symmetry in the structures, the faceted nano-columns with rectangular and hexagonal shapes were established in the simulation results. Furthermore, for revealing the influences of the anisotropic strength and the deposition rate theoretically on the crystallographic structure formations, various parameters adjusted in the numerical calculations were also investigated. Not only the morphologies but also the surface roughnesses for different processing conditions were distinctly demonstrated with the quantitative analysis of the simulations.

Impacts of channel deposition on the risk of flooding in a watershed

NASA Astrophysics Data System (ADS)

Ting-Yue, Hong; Chia-Ling, Chang

2017-04-01

Taiwan is located in East Asian where is always hit by typhoons. Typhoons usually bring huge amounts of rainfall and result in the problems of channel deposition. Deposition influences the functions of channel and increases the risk of flooding. The Luliao Reservoir Watershed is the case area in this study. It is the major water source for agricultural activity and domestic use. The objective of this study is to assess the possible impacts of channel deposition on the watershed environment. This study applies the Storm Water Management Model (SWMM) to predict the hydrologic responses and evaluate the risk of flooding. The results show that the decrease of cross section induced by deposition in a channel may increase the risk of flooding and impact the safety of watershed environment. Therefore, canal desilting is important in channel regulation. The discussion and analysis can be useful references for channel regulation.

Effects of annealing temperature on morphology and thickness of samarium electrodeposited thin films

DOE PAGES

Sims, Nathan J.; Stracener, Daniel W.; Boll, Rose Ann; ...

2016-05-17

Electroplated depositions of Sm were prepared using a vertical well-type electrodeposition unit with an aqueous ammonium acetate electrolyte system, with an average deposition yield just over 87%. The depositions were analyzed for morphology and thickness by scanning electron microscopy (SEM) and chemical composition by energy dispersion X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) before and after firing. The depositions were fired at 125–700 °C, while varying the heating rate from 0.5 to 10 °C/min in either an oxidizing or reducing atmosphere. A heating rate of 10 °C/min was slow enough to prevent disruption of the deposition morphology during firing.more » Furthermore, a gas sweep enhanced the removal of any organic substituents, with an oxidizing environment being more advantageous than a reducing environment.« less

Cross-system nutrient transport: effects of locally-derived aeolian dust on oligotrophic lakes in West Greenland

NASA Astrophysics Data System (ADS)

Bullard, J. E.; Anderson, N. J.; McGowan, S.; Prater, C.; Watts, M.; Whitford, E.

2017-12-01

Terrestrially-derived nutrients can strongly affect production in aquatic environments. However, while some research has focused on nutrient delivery via hydrological inputs, the effects of atmospheric dry deposition are comparatively understudied. This paper examines the influence of aeolian-derived elements on water chemistry and microbial nutrient-limitation in oligotrophic lakes in West Greenland. Estimates of seasonal dust deposition and elemental leaching rates are combined with lake nutrient concentration measurements to establish the role of glacio-fluvial dust deposition in shaping nutrient stoichiometry of downwind lakes. The bioavailability of dust-associated elements is also explored using enzyme assays designed to indicate nutrient-limitation in microbial communities sampled across a dust deposition gradient. Together, these analyses demonstrate the importance of atmospheric dust inputs on hydrologically-isolated lakes found in arid high-latitude environments and demonstrate the need to better understand the role of aeolian deposition in cross-system nutrient transport.

Effect of deforestation on stream water chemistry in the Skrzyczne massif (the Beskid Śląski Mountains in southern Poland).

PubMed

Kosmowska, Amanda; Żelazny, Mirosław; Małek, Stanisław; Siwek, Joanna Paulina; Jelonkiewicz, Łukasz

2016-10-15

The purpose of the study was to identify the factors affecting stream water chemistry in the small mountain catchments deforested to varying degrees, from 98.7 to 14.1%, due to long-term acid deposition. Water samples were collected monthly in 2013 and 2014 from 17 streams flowing across three distinct elevation zones in the Skrzyczne massif (Poland): Upper, Middle and Lower Forest Zone. Chemical and physical analyses, including the pH, electrical conductivity (EC), total mineral content (Mt), water temperature, and the concentrations of Ca(2+), Mg(2+), Na(+), K(+), HCO3(-), SO4(2-), Cl(-), and NO3(-), were conducted. Based on Principal Component Analysis (PCA), the most important factor affecting water chemistry was human impact associated with changes in pH, SO4(2-) concentration, and the concentration of most of the main ions. The substantial acidity of the studied environment contributed to the exclusion of natural factors, associated with changes in discharge, from the list of major factors revealed by PCA. All of the streams were characterized by very low EC, Mt, and low concentrations of the main ions such as Ca(2+) and HCO3(-). This is the effect of continuous leaching of solutes from the soils by acidic precipitation. The lowest parameter values were measured for the streams situated in the Upper Forest Zone, which is associated with greater acid deposition at the higher elevations. In the streams located in the Upper Forest Zone, a higher percentage of SO4(2-) occurred than in the streams situated in the Middle and Lower Forest Zones. However, the largest share of SO4(2-) was measured in the most deforested catchment. The saturation of the studied deforested catchment with sulfur compounds is reflected by a positive correlation between SO4(2-) and discharge. Hence, a forest acts as a natural buffer that limits the level of acidity in the natural environment caused by acidic atmospheric deposition. Copyright © 2016 Elsevier B.V. All rights reserved.

Investigating Rare Earth Element Systematics in the Marcellus Shale

NASA Astrophysics Data System (ADS)

Yang, J.; Torres, M. E.; Kim, J. H.; Verba, C.

2014-12-01

The lanthanide series of elements (the 14 rare earth elements, REEs) have similar chemical properties and respond to different chemical and physical processes in the natural environment by developing unique patterns in their concentration distribution when normalized to an average shale REE content. The interpretation of the REE content in a gas-bearing black shale deposited in a marine environment must therefore take into account the paleoredox conditions of deposition as well as any diagenetic remobilization and authigenic mineral formation. We analyzed 15 samples from a core of the Marcellus Shale (Whipkey ST1, Greene Co., PA) for REEs, TOC, gas-producing potential, trace metal content, and carbon isotopes of organic matter in order to determine the REE systematics of a black shale currently undergoing shale gas development. We also conducted a series of sequential leaching experiments targeting the phosphatic fractions in order to evaluate the dominant host phase of REEs in a black shale. Knowledge of the REE system in the Marcellus black shale will allow us to evaluate potential REE release and behavior during hydraulic fracturing operations. Total REE content of the Whipkey ST1 core ranged from 65-185 μg/g and we observed three distinct REE shale-normalized patterns: middle-REE enrichment (MREE/MREE* ~2) with heavy-REE enrichment (HREE/LREE ~1.8-2), flat patterns, and a linear enrichment towards the heavy-REE (HREE/LREE ~1.5-2.5). The MREE enrichment occurred in the high carbonate samples of the Stafford Member overlying the Marcellus Formation. The HREE enrichment occurred in the Union Springs Member of the Marcellus Formation, corresponding to a high TOC peak (TOC ~4.6-6.2 wt%) and moderate carbonate levels (CaCO3 ~4-53 wt%). Results from the sequential leaching experiments suggest that the dominant host of the REEs is the organic fraction of the black shale and that the detrital and authigenic fractions have characteristic MREE enrichments. We present our conclusions on the impact of depositional setting and diagenetic remobilization and authigenic mineral formation on the REE system in the Marcellus Shale.

Monitoring Atmospheric Deposition of Nitrogen in Alpine Environments in Rocky Mountain and Yosemite National Parks, USA

NASA Astrophysics Data System (ADS)

Roop, H. A.; Clow, D. W.; Mills, J.; Fenn, M. E.

2011-12-01

Recent increases in atmospheric deposition of nitrogen (N) in the western U.S. have adversely impacted surface water quality and changed the composition of aquatic biota in high-elevation lakes. Existing N deposition data are generally not spatially diverse; representation of remote wilderness areas and high-elevation watersheds is often lacking, making it difficult to assess the importance of variations in N deposition on water quality impacts. This study aims to better understand N deposition in remote environments, particularly in alpine environments, where both the quantity and environmental impact of atmospheric N deposition are poorly understood. Understanding the impacts of N deposition on these environments is important for National Park resource and water-quality managers. Using ion-exchange resin (IER) collectors, seasonal through-fall of nitrogen was measured at 29 sites in the Rocky Mountains and 21 sites in the Sierra Nevada from 2006-2011. The IER collectors, deployed in pairs, represent geographically diverse transects aimed to quantify the spatial distribution of nitrogen deposition. Placed on talus slopes or in areas of exposed bedrock, the IER collectors were installed immediately following snowmelt (June/July) and replaced with new collectors prior to the first snowfall (September). Following spring melt, the collectors deployed over the winter were exchanged with new collectors. These seasonal swaps capture winter/spring and summer/fall deposition. A majority of the sites were paired with seasonal surface-water quality samples, allowing for comparison with nitrate levels in surface waters. In the lab, N compounds are eluted from the resins, then diluted and analyzed on an ion- chromatograph. Preliminary data from 2006, representing 16 sites with uncontaminated samples in Rocky Mountain National Park, suggest higher nitrogen deposition on the east side of the park. Average summer N deposition for an 85-day exposure period at the eastern slope sites was 0.85 ± 0.21 kg/ha, and west-slope sites averaged 0.69 ± 0.12 kg/ha. Greater N deposition on the eastern slope may be related to seasonal upslope (easterly) winds, common during the spring and summer, which transport urban and agricultural pollutants into the mountains. However, an ANOVA analysis indicated that the difference in mean N deposition of the east- and west-sides were not statistically different at p < 0.05. Due to a small sample size, more data are currently being analyzed to determine if these results are representative. Ongoing analysis of samples collected from 2007-2011, in both Rocky Mountain and Yosemite National Parks, will help to place these preliminary results in context and build a more robust database from which the impacts of N deposition on high-elevation watersheds can be quantitatively determined.

Ion beam sputtering of in situ superconducting Y-Ba-Cu-O films

NASA Astrophysics Data System (ADS)

Klein, J. D.; Yen, A.; Clauson, S. L.

1990-05-01

Oriented superconducting YBa2Cu3O7 thin films were deposited on yttria stabilized zirconia and SrTiO3 substrates by ion-beam sputtering of a nonstoichiometric oxide target. The films exhibited zero-resistance critical temperatures as high as 83.5 K without post-deposition anneals. Both the deposition rate and the c-lattice parameter data displayed two distinct regimes of dependence on the beam power of the ion source. Low-power sputtering yielded films with large c-dimensions and low Tc. Higher-power sputtering produced a continuous decrease in the c-lattice parameter and increase in critical temperature. Films having the smaller c-lattice parameters were Cu rich. The Cu content of films deposited at beam voltages of 800 V and above increased with increasing beam power.

Deformation, geochemistry, and origin of massive sulfide deposits, Gossan lead district, Virginia.

USGS Publications Warehouse

Gair, J.E.; Slack, J.F.

1984-01-01

Lenses and layers of massive sulphides comprise a discontinuous horizon in the late Proterozoic metasedimentary Ashe formation. The folded and brecciated sulphides include pyrrhotite, minor chalcopyrite, sphalerite and pyrite, and rare arsenopyrite and galena. The deposits were mined for supergene copper, later for gossan iron, and finally for sulphur. The Ashe formation is interpreted to be marine turbidites, and contains lenses of mafic rocks of probable tholeiitic basalt parentage. Mineralogically and chemically distinctive rocks - for the Ashe formation - are interbedded with the sulphides and may represent metamorphosed alteration zones and/or mixed chemical and clastic sediments. The sulphide deposits are interpreted as syngenetic sediments, modified by deformation during metamorphism. Their deposition occurred in a deep, elongate marine basin overlying a crustal rift zone.-G.J.N.

Strukturalny zapis procesów akumulacyjno-deflacyjnych w wydmie wałowej we wschodniej części Kotliny Sandomierskiej (Ukraina)

NASA Astrophysics Data System (ADS)

Zieliński, Paweł; Semeniuk, Izabela

2008-01-01

During the studies of aeolian forms in the central part of the Lubaczów-Jaworów Plateau, in the borderland between Poland and Ukraine (Fig. 1), a special attention was given to lithologic features of deposits building a ridge dune, which is situated to the NE of Wola Arłamowa village. These deposits are characterized by distinct cyclic variability. This fact determined us to undertake investigations in order to reconstruct aerodynamic conditions under which such deposit variability had appeared. These investigations included: a) geomorphological mapping of the ridge dune and its immediate vicinity, b) identification of texture and structure of deposits building the form, c) measurements of scale and frequency of lithofacies, d) measurements of structural directional elements, and e) identification of primary deposition environments according to the classification by Hunter (1977) and Borówka (2001), described according to the suggestions published by Zieliński and Issmer (2008). Based on the lithologic features of dune building material (Figs 2, 3), we distinguished two deflation-accumulation cycles. The first one is recorded within the south-eastern slope of the dune, and it is characterized by the occurrence of sand sets with high-angle inclined stratification, which are separated by reactivation surfaces (Figs 2D, 3B). Sand was deposited on the leeward slope by wind from a predominant direction. The formation of reactivation surfaces is regarded as a result of the leeward slope exposure to winter strong wind from a direction completely different from the predominant one (McKee 1966; Borówka 1980; Hunter and Rubin 1983; Zieliński et al. in press). Therefore, we can assume that this change of wind direction occurred in annual rhythm. The second cycle was most completely recorded in the crest zone of the dune. It consists, from bottom to top, of the following lithofacies: RC→MR→PB→DT (Figs 2D, 3A). This cycle evidences wind from a slightly variable direction but with increasing velocity that resulted in increased deposition, and after exceeding the threshold value — increased deflation (Fig. 4). The nature of deposition can be compared with the described in literature wedge stratification (McKee 1966; McKee et al. 1971; Izmaiłow 2001). During this cycle the aerodynamic conditions changed in considerably shortened periods — from several days to several weeks. The authors suppose that this variability was associated with deepening, travelling to the east, and filling up of dynamic lows.

Modeling of an industrial environment: external dose calculations based on Monte Carlo simulations of photon transport.

PubMed

Kis, Zoltán; Eged, Katalin; Voigt, Gabriele; Meckbach, Reinhard; Müller, Heinz

2004-02-01

External gamma exposures from radionuclides deposited on surfaces usually result in the major contribution to the total dose to the public living in urban-industrial environments. The aim of the paper is to give an example for a calculation of the collective and averted collective dose due to the contamination and decontamination of deposition surfaces in a complex environment based on the results of Monte Carlo simulations. The shielding effects of the structures in complex and realistic industrial environments (where productive and/or commercial activity is carried out) were computed by the use of Monte Carlo method. Several types of deposition areas (walls, roofs, windows, streets, lawn) were considered. Moreover, this paper gives a summary about the time dependence of the source strengths relative to a reference surface and a short overview about the mechanical and chemical intervention techniques which can be applied in this area. An exposure scenario was designed based on a survey of average German and Hungarian supermarkets. In the first part of the paper the air kermas per photon per unit area due to each specific deposition area contaminated by 137Cs were determined at several arbitrary locations in the whole environment relative to a reference value of 8.39 x 10(-4) pGy per gamma m(-2). The calculations provide the possibility to assess the whole contribution of a specific deposition area to the collective dose, separately. According to the current results, the roof and the paved area contribute the most part (approximately 92%) to the total dose in the first year taking into account the relative contamination of the deposition areas. When integrating over 10 or 50 y, these two surfaces remain the most important contributors as well but the ratio will increasingly be shifted in favor of the roof. The decontamination of the roof and the paved area results in about 80-90% of the total averted collective dose in each calculated time period (1, 10, 50 y).

Impact of enhanced ozone deposition and halogen chemistry on tropospheric ozone over the Northern Hemisphere

EPA Science Inventory

Fate of ozone in marine environments has been receiving increased attention due to the tightening of ambient air quality standards. The role of deposition and halogen chemistry is examined through incorporation of an enhanced ozone deposition algorithm and inclusion of halogen ch...

Enthalpy and high temperature relaxation kinetics of stable vapor-deposited glasses of toluene

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhattacharya, Deepanjan; Sadtchenko, Vlad, E-mail: vlad@gwu.edu

Stable non-crystalline toluene films of micrometer and nanometer thicknesses were grown by vapor deposition at distinct rates and probed by fast scanning calorimetry. Fast scanning calorimetry is shown to be extremely sensitive to the structure of the vapor-deposited phase and was used to characterize simultaneously its kinetic stability and its thermodynamic properties. According to our analysis, transformation of vapor-deposited samples of toluene during heating with rates in excess 10{sup 5} K s{sup −1} follows the zero-order kinetics. The transformation rate correlates strongly with the initial enthalpy of the sample, which increases with the deposition rate according to sub-linear law. Analysismore » of the transformation kinetics of vapor-deposited toluene films of various thicknesses reveal a sudden increase in the transformation rate for films thinner than 250 nm. The change in kinetics seems to correlate with the surface roughness scale of the substrate. The implications of these findings for the formation mechanism and structure of vapor-deposited stable glasses are discussed.« less

Rhenium-osmium evidence for regional mineralization in southwestern north america.

PubMed

McCandless, T E; Ruiz, J

1993-09-03

More than 40 base metal porphyry ore deposits in southwestern North America are associated with the Laramide orogeny (about 90 million to 50 million years ago). Rhenium-osmium dates on molybdenite, a rhenium-enriched sulfide common in many of the deposits, reveal that in individual deposits mineralization occurs near the final stages of magmatic activity irrespective of the time of inception, magnitude, or duration of magmatism. Deposits that differ widely in location and in the extent and timing of magmatism have nearly identical ages for mineralization. Rhenium-osmium-ages suggest that mineralization occurred during two distinct intervals from about 74 million to 70 million years ago and from 60 million to 55 million years ago. Most deposits that formed in the oldest interval are within the older Precambrian basement of northwestern Arizona, whereas the younger deposits are restricted to the younger Precambrian basement in southern Arizona and northern Mexico. Synchronous, widespread mineralization indicates that similar crust-mantle interaction occurred on a regional scale for ore deposits once thought to be the product of localized processes.

Using XRF Geochemical Data to Differentiate Storm Event Deposits in a Backbarrier Lake in Coastal Louisiana

NASA Astrophysics Data System (ADS)

Dietz, M.; Liu, K. B.; Bianchette, T. A.; Yao, Q.; McCloskey, T.

2016-12-01

Hurricanes Gustav and Ike consecutively impacted coastal Louisiana in 2008 and generated significant storm surges. Three sediment cores taken from Bay Champagne, a coastal backbarrier lake near Port Fourchon, Louisiana, clearly show a deposition layer of clastic sediment up to 17 cm thick attributable to these two storms. X-ray fluorescence (XRF) analysis indicates that the two storm events can be distinguished from one another based on contrasting geochemical profiles. The bottom layer, presumably deposited by Hurricane Gustav, has high concentrations of S, Cl, Ca, and Sr, suggesting a strong marine influence. The top layer, presumably attributed to Hurricane Ike, has high concentrations of Ti, Mn, Fe and Zn, indicative of material of terrestrial origin. The elemental concentration profiles suggest that the storm deposits in each core were deposited through two distinct hydrological processes: a storm surge -driven marine intrusion during Hurricane Gustav, followed by intensive freshwater flooding during Hurricane Ike. Using these deposits as modern analogs, this technique could be applied to characterize older storm layers in the sedimentary record and potentially provide information about their respective depositional mechanisms.

Analysis of Lunar Pyroclastic Glass Deposit FeO Abundances by LRO Diviner

NASA Technical Reports Server (NTRS)

Allen, Carlton C.; Greenhagen, Benjamin T.; DonaldsonHanna, Kerri L.; Paige, David A.

2011-01-01

Telescopic observations and orbital images of the Moon reveal at least 75 deposits, often tens to hundreds of km across, that mantle mare or highland surfaces [1]. These deposits are interpreted as the products of pyroclastic eruptions and designated herein as lunar pyroclastic deposits (LPD). They are understood to be composed primarily of sub-millimeter beads of basaltic composition, ranging from glassy to partially-crystallized [2]. Delano [3] documented 25 distinct pyroclastic bead compositions in lunar soil samples, though the source deposits for most of these beads have not been identified. The pyroclastic deposits are important for many reasons. Petrology experiments and modeling have demonstrated that the pyroclastic glasses are the deepest-sourced and most primitive basalts on the Moon [4]. Recent analyses have documented the presence of water in these glasses, demonstrating that the lunar interior is considerably more volatile-rich than previously understood [5]. Experiments have shown that the iron-rich pyroclastic glasses release the highest percentage of oxygen of any Apollo soils, making these deposits promising lunar resources [6].

Hydrated mineral stratigraphy of Ius Chasma, Valles Marineris

USGS Publications Warehouse

Roach, L.H.; Mustard, J.F.; Swayze, G.; Milliken, R.E.; Bishop, J.L.; Murchie, S.L.; Lichtenberg, K.

2010-01-01

New high-resolution spectral and morphologic imaging of deposits on walls and floor of Ius Chasma extend previous geomorphic mapping, and permit a new interpretation of aqueous processes that occurred during the development of Valles Marineris. We identify hydrated mineralogy based on visible-near infrared (VNIR) absorptions. We map the extents of these units with CRISM spectral data as well as morphologies in CTX and HiRISE imagery. Three cross-sections across Ius Chasma illustrate the interpreted mineral stratigraphy. Multiple episodes formed and transported hydrated minerals within Ius Chasma. Polyhydrated sulfate and kieserite are found within a closed basin at the lowest elevations in the chasma. They may have been precipitates in a closed basin or diagenetically altered after deposition. Fluvial or aeolian processes then deposited layered Fe/Mg smectite and hydrated silicate on the chasma floor, postdating the sulfates. The smectite apparently was weathered out of Noachian-age wallrock and transported to the depositional sites. The overlying hydrated silicate is interpreted to be an acid-leached phyllosilicate transformed from the underlying smectite unit, or a smectite/jarosite mixture. The finely layered smectite and massive hydrated silicate units have an erosional unconformity between them, that marks a change in surface water chemistry. Landslides transported large blocks of wallrock, some altered to contain Fe/Mg smectite, to the chasma floor. After the last episode of normal faulting and subsequent landslides, opal was transported short distances into the chasma from a few m-thick light-toned layer near the top of the wallrock, by sapping channels in Louros Valles. Alternatively, the material was transported into the chasma and then altered to opal. The superposition of different types of hydrated minerals and the different fluvial morphologies of the units containing them indicate sequential, distinct aqueous environments, characterized by alkaline, then circum-neutral, and finally very acidic surface or groundwater chemistry. ?? 2009 Elsevier Inc. All rights reserved.

Multiple Magma Batches Recorded in Tephra Deposits from the Toba Complex, Sumatra.

NASA Astrophysics Data System (ADS)

Pearce, N. J. G.; Westgate, J.; Gatti, E.

2015-12-01

The Toba Caldera Complex is the largest Quaternary caldera on Earth, and has generated three voluminous and compositionally similar rhyolitic tuffs, viz. the Oldest (OTT, 800 ka), Middle (MTT, ~500 ka) and Youngest Toba Tuffs (YTT, 75 ka). These tephra deposits are widespread across Indonesia, Malaysia, South China Sea, Sea of Bengal, India and Indian Ocean and provide useful stratigraphic markers in oceanic, lacustrine and terrestrial environments. Single shard trace element analysis of these deposits reveals the changing availability of different batches of magma through time, with Sr, Ba and Y contents defining 5 discrete magma populations in YTT, 4 populations in MTT and only a single, low Ba population in OTT. Within an individual eruption these populations are clearly distinct, but between eruptions (e.g. MTT and YTT) some of these populations overlap while others do not, indicating both the longevity (and/or continuous supply of fresh material) and evolution of these magma batches in the Toba Complex. Major element compositions of the different groups show equilibration at different pressures (based on Q'-Ab'-Or'), with the equilibration of low Ba populations at ~160 MPa, increasing to depths of ~210 MPa for the highest Ba population. The proportions of different populations of glass in distal YTT shows that relatively little of the high Ba population makes it into the distal record across India, and that this population appears to be over-represented in the proximal free glass and pumice from the caldera walls. This data may shed light on magma availability and tephra dispersal during the YTT eruption. Similarly, the glass composition of individual pumices from proximal deposits record regional, compositional and temporal differences in the erupted products. These show, for example, the apparent mingling of some of the magma batches and also that the high Ba population appears early (i.e. stratigraphically lower) in the northern caldera wall.

Mineral magnetic characteristics of the late Quaternary coastal red sands of Bheemuni, East Coast (India)

NASA Astrophysics Data System (ADS)

Srivastava, Priyeshu; Sangode, S. J.; Parmar, Nikita; Meshram, D. C.; Jadhav, Priyanka; Singhvi, A. K.

2016-11-01

The voluminous red sand deposits of Bheemuni in the east coast of India provide record of coastal land-sea interaction during the late Quaternary climatic and eustatic oscillations. Limited information on the origin and depositional environments of these red sands and their chronology is available. We studied two inland to coast cross profiles from Bheemuni red sand deposits using mineral magnetism, color characteristics and Citrate-bicarbonate-dithionite (CBD) extractable pedogenic iron oxides over 23 horizons along with optically stimulated luminescence (OSL) chronology at 6 horizons. The oldest exposed bed had an optical age of 48.9 ± 1.7 ka. Differential ages between the two parallel sections (SOS = 48.9 ± 1.7 to 12.1 ± 0.3 ka and IMD = 29.3 ± 3.5 ka) suggest laterally shifting fluvial sedimentation. Both the profiles show significant amount of antiferromagnetic oxide (hematite) along with ferrimagnetic (magnetite/maghemite) mineral composition. The granulometric (/domain-) sensitive parameters (χFD, χARM, SIRM/χLF and χARM/χLF) indicate variable concentration of superparamagnetic (SP) and single domain (SD) particles between the two profiles. The higher frequency dependent and pedogenic magnetic susceptibilities (χFD and χpedo) in the younger (IMD) profile suggest enhanced pedogenesis under a warm-wet climate post 29.3 ka and also during Holocene. A combination of hard isothermal remanent magnetization (HIRM) and redness rating (RR) index indicates distinct but variable concentration of a) crystalline and b) poorly crystalline (pigmentary) hematites in both the profiles. We consider that the former (#a) is derived from hinterland red soils and possibly due to post-depositional diagenesis, and the latter (#b) precipitated from the dissolved iron under fluvial regime imparting the unique red coloration to Bheemuni sands. Partial to complete alteration of ferromagnesian minerals due to pedogenesis in hinterlands under warm-wet climate was therefore the principal source of reddening of the Bheemuni sands.

Post-collisional deposits in the Zagros foreland basin: Implications for diachronous underthrusting

NASA Astrophysics Data System (ADS)

Pirouz, Mortaza

2017-11-01

Detailed sedimentology of the Neogene foreland basin deposits is investigated and classified into 11 lithofacies associations with respect to their paleo-sedimentary environments. The foreland deposits reveal a single coarsening-upward mega-sequence with continuous passage from back-bulge to forebulge, foredeep, and wedge-top sedimentary environments. The Gachsaran deposits form the base of the foreland strata and consist mainly of three different lithofacies associations including fluvial, marine, and sabkha deposits in the eastern Zagros in Fars, and are typically dominated with evaporites toward the west in the Dezful and Kirkuk embayments. The Mishan Formation has three different shallow-marine lithofacies associations in a vertical succession representing foredeep deposits in the eastern Zagros, which tapers toward the Dezful embayment and disappears in Iraq. The Agha Jari distal wedge-top deposits also contain three different lithofacies associations including delta deposits mostly in the Fars, tidal flat deposits in Dezful and Mesopotamia basin, and continental fluvial deposits across the entire Zagros. The uppermost synorogenic Bakhtiari Formation represents proximal wedge-top deposits and consists mainly of two main lithofacies associations including shallow marine and fluvial deposits, within which the fluvial succession is divided into three sub-lithofacies associations with respect to distance from the mountain front and hydraulic power of the river networks. Synthetizing sedimentary facies association with age constraints of the old foreland deposits near the Zagros suture in the High Zagros area suggests that a considerable part of the Arabian plate has been removed at the northern edge by underthrusting and erosion. Moreover, preservation of the young distal foreland deposits near the suture in the western Zagros implies that the magnitude and rate of removal of the proximal foreland deposits have been inconstant along-strike the belt and decreases toward the east.

Assessment of Lead and Beryllium deposition and adsorption to exposed stream channel sediments

NASA Astrophysics Data System (ADS)

Pawlowski, E.; Karwan, D. L.

2016-12-01

The fallout radionuclides Beryllium-7 and Lead-210 have been shown to be effective sediment tracers that readily bind to particles. The adsorption capacity has primarily been assessed in marine and coastal environments with an important assumption being the radionuclides' uniform spatial distribution as fallout from the atmosphere. This neglects localized storm events that may mine stratospheric reserves creating variable distributions. To test this assumption atmospheric deposition is collected at the University of Minnesota St. Paul Campus weather station during individual storm events and subsequently analyzed for Beryllium-7 and Lead-210. This provides further insight into continental effects on radionuclide deposition. The study of Beryllium-7 and Lead-210 adsorption in marine and coastal environments has provided valuable insights into the processes that influence the element's binding to particles but research has been limited in freshwater river environments. These environments have greater variation in pH, iron oxide content, and dissolved organic carbon (DOC) levels which have been shown to influence the adsorption of Beryllium and Lead in marine settings. This research assesses the adsorption of Beryllium and Lead to river sediments collected from in-channel deposits by utilizing batch experiments that mimic the stream conditions from which the deposits were collected. Soils were collected from Difficult Run, VA, and the West Swan River, MN. Agitating the soils in a controlled solution of known background electrolyte and pH while varying the level of iron oxides and DOC in step provides a better understanding of the sorption of Lead and Beryllium under the conditions found within freshwater streams. Pairing the partitioning of Lead and Beryllium with their inputs to streams via depositional processes, from this study and others, allows for their assessment as possible sediment tracers and age-dating tools within the respective watersheds.

Taphonomy of fossils from the hominin-bearing deposits at Dikika, Ethiopia.

PubMed

Thompson, Jessica C; McPherron, Shannon P; Bobe, René; Reed, Denné; Barr, W Andrew; Wynn, Jonathan G; Marean, Curtis W; Geraads, Denis; Alemseged, Zeresenay

2015-09-01

Two fossil specimens from the DIK-55 locality in the Hadar Formation at Dikika, Ethiopia, are contemporaneous with the earliest documented stone tools, and they collectively bear twelve marks interpreted to be characteristic of stone tool butchery damage. An alternative interpretation of the marks has been that they were caused by trampling animals and do not provide evidence of stone tool use or large ungulate exploitation by Australopithecus-grade hominins. Thus, resolving which agents created marks on fossils in deposits from Dikika is an essential step in understanding the ecological and taphonomic contexts of the hominin-bearing deposits in this region and establishing their relevance for investigations of the earliest stone tool use. This paper presents results of microscopic scrutiny of all non-hominin fossils collected from the Hadar Formation at Dikika, including additional fossils from DIK-55, and describes in detail seven assemblages from sieved surface sediment samples. The study is the first taphonomic description of Pliocene fossil assemblages from open-air deposits in Africa that were collected without using only methods that emphasize the selective retention of taxonomically-informative specimens. The sieved assemblages show distinctive differences in faunal representation and taphonomic modifications that suggest they sample a range of depositional environments in the Pliocene Hadar Lake Basin, and have implications for how landscape-based taphonomy can be used to infer past microhabitats. The surface modification data show that no marks on any other fossils resemble in size or shape those on the two specimens from DIK-55 that were interpreted to bear stone tool inflicted damage. A large sample of marks from the sieved collections has characteristics that match modern trampling damage, but these marks are significantly smaller than those on the DIK-55 specimens and have different suites of characteristics. Most are not visible without magnification. The data show that the DIK-55 marks are outliers amongst bone surface damage in the Dikika area, and that trampling is not the most parsimonious interpretation of their origin. Copyright © 2015 Elsevier Ltd. All rights reserved.

Diatoms in sediments of perennially ice-covered Lake Hoare, and implications for interpreting lake history in the McMurdo Dry Valleys of Antarctica

USGS Publications Warehouse

Spaulding, S.A.; McKnight, Diane M.; Stoermer, E.F.; Doran, P.T.

1997-01-01

Diatom assemblages in surficial sediments, sediment cores, sediment traps, and inflowing streams of perennially ice-covered Lake Hore, South Victorialand, Antarctica were examined to determine the distribution of diatom taxa, and to ascertain if diatom species composition has changed over time. Lake Hoare is a closed-basin lake with an area of 1.8 km2, maximum depth of 34 m, and mean depth of 14 m, although lake level has been rising at a rate of 0.09 m yr-1 in recent decades. The lake has an unusual regime of sediment deposition: coarse grained sediments accumulate on the ice surface and are deposited episodically on the lake bottom. Benthic microbial mats are covered in situ by the coarse episodic deposits, and the new surfaces are recolonized. Ice cover prevents wind-induced mixing, creating the unique depositional environment in which sediment cores record the history of a particular site, rather than a lake=wide integration. Shallow-water (<1 m) diatom assemblages (Stauroneis anceps, Navicula molesta, Diadesmis contenta var. parallela, Navicula peraustralis) were distinct from mid-depth (4-16 m) assemblages (Diadesmis contenta, Luticola muticopsis fo. reducta, Stauroneis anceps, Diadesmis contenta var. parallela, Luticola murrayi) and deep-water (2-31 m) assemblages (Luticola murrayi, Luticola muticopsis fo. reducta, Navicula molesta. Analysis of a sediment core (30 cm long, from 11 m water depth) from Lake Hoare revealed two abrupt changes in diatom assemblages. The upper section of the sediment core contained the greatest biomass of benthic microbial mat, as well as the greatest total abundance and diversity of diatoms. Relative abundances of diatoms in this section are similar to the surficial samples from mid-depths. An intermediate zone contained less organic material and lower densities of diatoms. The bottom section of core contained the least amount of microbial mat and organic material, and the lowest density of diatoms. The dominant process influencing species composition and abundance of diatom assemblages in the benthic microbial mats is episodic deposition of coarse sediment from the ice surface.

The contribution of lateritization processes to the formation of the kaolin deposits from eastern Amazon

NASA Astrophysics Data System (ADS)

da Costa, Marcondes Lima; Sousa, Daniel José Lima; Angélica, Rômulo Simões

The eastern region of the Amazon is home to the most important kaolin bauxite producing district in Brazil, referred to as the Paragominas-Capim kaolin bauxite district, which has a reserve of at least 1.0 billion tons of high-quality kaolin used in the paper coating industry. The kaolin deposits are closely related to sedimentary rocks of the Parnaíba basin and their lateritic cover. Two large deposits are already being mined: IRCC (Ipixuna) and PPSA (Paragominas). The geology of the IRCC mine is comprised of the kaolin-bearing lower unit (truncated mature laterite succession derived from the Ipixuna/Itapecuru formation) and the upper unit (immature lateritized Barreiras formation). The lower kaolin unit is characterized by a sandy facies at the bottom and a soft (ore) with flint facies at the top. It is formed by kaolinite, quartz, some iron oxi-hydroxides, mica and several accessories and heavy minerals. The <2 μm kaolinite crystallites only correspond to 41.3-58.3% of the soft kaolin, and large booklets of 15-300 μm are common. The degree of structure order of kaolinite decreases towards the flint kaolin. The chemical composition of the soft kaolin is similar to the theoretical chemical composition of kaolinite, with low iron content, and can be well correlated to most kaolin deposits in the region. The distribution pattern of chemical elements from sandy to flint kaolin (lower unit) suggests a lateritic evolution and erosive truncation. This is quite distinct from the upper unit, which has a mineralogical and chemical pathway relating it to a complete immature lateritic profile. The geological evolution of the IRCC kaolin is similar to that of other deposits in the eastern Amazon region, being comprised of: parent rocks formed in an estuarine marine and fluvio-laccustrine environment during the early Cretaceous; establishment of mature lateritization with the formation of kaolin in the Eocene; marine transgression and regression - (Pirabas and Barreiras formation) with kaolin profile erosion and forward movement of deferruginization and flintization during the Miocene after partial mangrove covering; and immature lateritization - partial kaolin ferruginization during the Pleistocene.

Characteristics of depositional environment and evolution of Upper Cretaceous Mishrif Formation, Halfaya Oil field, Iraq based on sedimentary microfacies analysis

NASA Astrophysics Data System (ADS)

Zhong, Yuan; Zhou, Lu; Tan, Xiucheng; Guo, Rui; Zhao, Limin; Li, Fei; Jin, Zhimin; Chen, Yantao

2018-04-01

As one of the most important carbonate targets in the Middle East, Upper Cretaceous Mishrif Formation has been highlighted for a long time. Although consensus has been reached on the overall sedimentary background, disputes still exist in understanding the sedimentary environment changes among sub-regions due to relatively limited research, rare outcrop, and incomplete drilled core, which hinders the analysis on sedimentary environment and thus the horizontal and vertical correlation. In this study, taking the Halfaya Oil Field as an example, the sedimentary microfacies analysis method was introduced to comprehensively characterize the cored interval of Mishrif Formation, including Single Layers MC1-1 to MA2. A total of 11 sedimentary microfacies are identified through system identification of sedimentary microfacies and environmental analysis, with reference to the standard microfacies classification in the rimmed carbonate platform. Then three kinds of environments are identified through microfacies assemblage analysis, namely restricted platform, open platform, and platform margin. Systematic analyses indicate that the deposits are mainly developed in the open platform and platform margin. Meanwhile, rock-electricity interpretation model is established according to the electricity response to cored intervals, and is then employed to interpret the uncored intervals, which finally helps build the sedimentary evolution pattern through horizontal and vertical correlation. It is proposed that the Single Layers MC1-1 to MB2-3 were deposited in the open platform featured by low water level, including sub-environments of low-energy shoal within platform and inter-shoal sea; Single Layers MB2-2 to MB1-2B were deposited in the open platform and platform margin, including sub-environments of high-energy shoal on the platform margin, low-energy shoal within platform, inter-shoal sea, and open sea; and Single Layers MB1-2A to MA2 were again deposited in the open platform with high water level, and the circumstance of open sea was dominant. The deposition of Single Layers MC1-1 to MA2 actually corresponded to a retrogradation-progradation process. Results of this study will not only provide significant guidance to the exploration and development of Mishrif Formation, Halfaya Oil Field, but also support that the theory of sedimentary environment correlation with adjacent areas is reliable.

Grain size analysis and depositional environment of shallow marine to basin floor, Kelantan River Delta

NASA Astrophysics Data System (ADS)

Afifah, M. R. Nurul; Aziz, A. Che; Roslan, M. Kamal

2015-09-01

Sediment samples were collected from the shallow marine from Kuala Besar, Kelantan outwards to the basin floor of South China Sea which consisted of quaternary bottom sediments. Sixty five samples were analysed for their grain size distribution and statistical relationships. Basic statistical analysis like mean, standard deviation, skewness and kurtosis were calculated and used to differentiate the depositional environment of the sediments and to derive the uniformity of depositional environment either from the beach or river environment. The sediments of all areas were varied in their sorting ranging from very well sorted to poorly sorted, strongly negative skewed to strongly positive skewed, and extremely leptokurtic to very platykurtic in nature. Bivariate plots between the grain-size parameters were then interpreted and the Coarsest-Median (CM) pattern showed the trend suggesting relationships between sediments influenced by three ongoing hydrodynamic factors namely turbidity current, littoral drift and waves dynamic, which functioned to control the sediments distribution pattern in various ways.

Dinocyst taphonomy, impact craters, cyst ghosts, and the Paleocene-Eocene thermal maximum (PETM)

USGS Publications Warehouse

Edwards, Lucy E.

2012-01-01

Dinocysts recovered from sediments related to the Chesapeake Bay impact structure in Virginia and the earliest Eocene suboxic environment in Maryland show strange and intriguing details of preservation. Features such as curled processes, opaque debris, breakage, microborings and cyst ghosts, among others, invite speculation about catastrophic depositional processes, rapid burial and biological and chemical decay. Selected specimens from seven cores taken in the coastal plain of Virginia and Maryland show abnormal preservation features in various combinations that merit illustration, description, discussion and further study. Although the depositional environments described are extreme, many of the features discussed are known from, or could be found in, other environments. These environments will show both similarities to and differences from the extreme environments here.

Thermochromic VO2 thin films deposited by magnetron sputtering for smart window applications

NASA Astrophysics Data System (ADS)

Fortier, Jean-Philippe

"Smart" windows are a perfect innovative example of technology that reduces our energy dependence and our impact on the environment while saving on the economical point of view. With the use of vanadium dioxide (VO2), a thermochromic compound, and this, as a thin coating, it would in fact be possible to control the sun's transmission of infrared light (heat) as a function of the surrounding environment temperature. In other words, its optical behavior would allow a more effective management of heat exchanges between a living venue and the outdoor environment. However, this type of window is still in a developmental stage. First, the oxide's deposition is not simple in nature. Based on a conventional deposition technique called magnetron sputtering mainly used in the fenestration industry, several factors such as the oxygen concentration and the substrate temperature during deposition can affect the coating's thermochromic behavior, and this, by changing its composition and crystallinity. Other control parameters such as the deposition rate, the pressure in the sputtering chamber and the choice of substrate may also modify the film microstructure, thereby varying its optical and electrical properties. In addition, several issues still persist as to its commercial application. For starters, the material's structural transition, related to the change of its optical properties, only occurs around 68°C. In addition, its low transparency and natural greenish colour are not visually appealing. Then, to this day, the deposition temperature required to crystallize and form the thermochromic oxide remains an obstacle for a possible large-scale application. Ultimately, although the material's change in temperature has been shown to be advantageous in situations of varying climate, the existing corrective solutions to these issues generate a deterioration of the thermochromic behavior. With no practical expertise on the material, this project was undertaken with certain objectives in mind. To start, we had to find a first recipe to obtain our first samples of the material. Using the literature as a starting point, several samples were deposited by magnetron sputtering while improving certain deposition conditions as well as varying influential deposition parameters. Once the oxide obtained, it was necessary to optimize the parameters not only to render thermochromic coatings with the highest possible quality, but also to determine each parameter's sensitivity. Characterization techniques such as microscopy, spectroscopy, ellipsometry, scanning electron microscopy, atomic force microscopy, Raman spectroscopy, x-ray diffraction and finally, time-of-flight secondary ion mass spectrometry were used to analyze different aspects of our multiple samples. Indeed, to mention only the ix most relevant observations, we were able to confirm that the microstructure, composition, most relevant observations, we were able to confirm that the microstructure, composition, crystallinity and film thickness have a significant impact on the coating's thermochromic behavior as well as on its optical properties. As a result, the oxygen concentration and the thickness had to be optimized and the deposition temperature, maximized. Reactive poisoning of the sputtering target is also a phenomenon that needs to be considered during deposition. Then, our sputtering target and substrate cleaning procedures were improved following certain observations. VO2 was equally found to be sensitive to small temperature gradients in addition of being highly dependent upon high deposition temperatures. Finally, the use of different substrates has subsequently shown that the film composition and microstructure can be altered. After mastering the deposition of thin VO2 films, we explored another path that we found to be quite innovative. A relatively new deposition technique called HiPIMS was put to the test based on its new characteristics, leading to believe that it had the potential of improving our coatings and allow a better application of the material. We first took some time to study and adapt to the technique's distinct characteristics, based on pulsed sputtering. After parameter optimization, the highly ionized sputtering flux allowed us to obtain more crystalline and denser coatings, with considerable homogeneity, less roughness and a higher purity than films obtained using conventional sputtering and than those described in the literature. With these features, it was possible to extract the material's optical constants and to obtain a change of transmission in the infrared (DeltaT2500 nm=61%) comparable to the best performing thermochromic samples documented in the literature, and this, at a substantially lower deposition temperature (300°C). This is a technical highlight, as conventional sputtering methods normally require temperatures above 400°C to form the oxide. In addition, our films had transition temperatures lower than that of the bulk material. The results seem to indicate that HiPIMS is promising and preferable for the deposition of VO2 films with respect to their practical use in the world of windows. (Abstract shortened by UMI.).

Anatomy and dynamics of a floodplain, Powder River, Montana, U.S.A.

USGS Publications Warehouse

Pizzuto, J.E.; Moody, J.A.; Meade, R.H.

2008-01-01

Centimeter-scale measurements on several Powder River floodplains provide insights into the nature of overbank depositional processes that created the floodplains; during a 20-year period after a major flood in 1978. Rising stages initially entered across a sill at the downriver end of the floodplains. Later, as stages continued to rise, water entered the floodplains through distinct low saddles along natural levees. The annual maximum depth of water over the levee crest averaged 0.19 in from 1983 through 1996, and the estimated flow velocities were approximately 0.15 m s-1. Water ponded in the floodplain trough, a topographic low between the natural levee and the pre-flood riverbank, and mud settled as thin layers of nearly constant thickness. Mud layers alternated with sand layers, which were relatively thick near the channel. Together, these beds created a distinctive natural levee. In some locations, individual flood deposits began as a thin mud layer that gradually coarsened upwards to medium-grained sand. Coarsening-upwards sequences form initially as mud because only the uppermost layers of water in the channel supply the first overbank flows, which are rich in mud but starved of sand. At successively higher stages, fine sands and then medium sands increase in concentration in the floodwater and are deposited as fine- and medium-sand layers overlying the initial mud layer. Theoretical predictions from mathematical models of sediment transport by advection and diffusion indicate that these processes acting alone are unlikely to create the observed sand layers of nearly uniform thickness that extend across much of the floodplain. We infer that other transport processes, notably bedload transport, must be important along Powder River. Even with the centimeter-scale measurements of floodplain deposits, daily hydraulic data, and precise annual surface topographic surveys, we were unable to determine any clear correspondence between the gauged flow record of overbank floods and the depositional layers mapped in the floodplain. These results provide a detailed example of floodplain deposits and depositional processes that should prove useful for interpreting natural levee deposits in a variety of geologic settings. Copyright ?? 2008, SEPM (Society for Sedimentary Geology).

Depositional environments and processes in Upper Cretaceous nonmarine and marine sediments, Ocean Point dinosaur locality, North Slope, Alaska

USGS Publications Warehouse

Phillips, R.L.

2003-01-01

A 178-m-thick stratigraphic section exposed along the lower Colville River in northern Alaska, near Ocean Point, represents the uppermost part of a 1500 m Upper Cretaceous stratigraphic section. Strata exposed at Ocean Point are assigned to the Prince Creek and Schrader Bluff formations. Three major depositional environments are identified consisting, in ascending order, of floodplain, interdistributary-bay, and shallow-marine shelf. Nonmarine strata, comprising the lower 140 m of this section, consist of fluvial distributaries, overbank sediments, tephra beds, organic-rich beds, and vertebrate remains. Tephras yield isotopic ages between 68 and 72.9 Ma, generally consistent with paleontologic ages of late Campanian-Maastrichtian determined from dinosaur remains, pollen, foraminifers, and ostracodes. Meandering low-energy rivers on a low-gradient, low-relief floodplain carried a suspended-sediment load. The rivers formed multistoried channel deposits (channels to 10 m deep) as well as solitary channel deposits (channels 2-5 m deep). Extensive overbank deposits resulting from episodic flooding formed fining-upward strata on the floodplain. The fining-upward strata are interbedded with tephra and beds of organic-rich sediment. Vertical-accretion deposits containing abundant roots indicate a sheet flood origin for many beds. Vertebrate and nonmarine invertebrate fossils along with plant debris were locally concentrated in the floodplain sediment. Deciduous conifers as well as abundant wetland plants, such as ferns, horsetails, and mosses, covered the coastal plain. Dinosaur skeletal remains have been found concentrated in floodplain sediments in organic-rich bone beds and as isolated bones in fluvial channel deposits in at least nine separate horizons within a 100-m-thick interval. Arenaceous foraminifers in some organic-rich beds and shallow fluvial distributaries indicate a lower coastal plain environment with marginal marine (bay) influence. Marginal marine strata representing interdistributary bay deposits overlie the nonmarine beds and comprise about 15 m of section. Extensive vegetated sand flats, shoals, and shallow channels overlain by shallow bay deposits (less than 7 m deep), containing storm-generated strata characterize the marginal marine beds. Abundant bioturbation and roots characterize the stratigraphic lowest bay deposits; bioturbated sediment, pelecypods, barnacles, and benthic microfossils are found in the overlying bay storm deposits. The sediments abruptly change upward from hummocky cross-stratified bay deposits to a muddy marsh deposit containing shallow organic-rich channels to prograding nonmarine to marginal marine beds. Transgressive, abundantly fossiliferous shallow-marine strata more than 13 m thick comprise the uppermost exposures at Ocean Point. The marine beds overlie nonmarine and bay strata and represent an environment dominated episodically by storms. The age of the marginal marine and marine beds is late Maastrichtian based on pollen. ?? 2003 Elsevier Ltd. All rights reserved.

Landscape characteristics of Rhizophora mangle forests and propagule deposition in coastal environments of Florida (USA)

USGS Publications Warehouse

Sengupta, R.; Middleton, B.; Yan, C.; Zuro, M.; Hartman, H.

2005-01-01

Field dispersal studies are seldom conducted at regional scales even though reliable information on mid-range dispersal distance is essential for models of colonization. The purpose of this study was to examine the potential distance of dispersal of Rhizophora mangle propagules by comparing deposition density with landscape characteristics of mangrove forests. Propagule density was estimated at various distances to mangrove sources (R. mangle) on beaches in southwestern Florida in both high-and low-energy environments, either facing open gulf waters vs. sheltered, respectively. Remote sensing and Geographic Information Systems were used to identify source forests and to determine their landscape characteristics (forest size and distance to deposition area) for the regression analyses. Our results indicated that increasing density of propagules stranded on beaches was related negatively to the distance of the deposition sites from the nearest stands of R. mangle and that deposition was greatly diminished 2 km or more from the source. Measures of fragmentation such as the area of the R. mangle forests were related to propagule deposition but only in low-energy environments. Our results suggest that geographic models involving the colonization of coastal mangrove systems should include dispersal dynamics at mid-range scales, i.e., for our purposes here, beyond the local scale of the forest and up to 5 km distant. Studies of mangrove propagule deposition at various spatial scales are key to understanding regeneration limitations in natural gaps and restoration areas. Therefore, our study of mid-range propagule dispersal has broad application to plant ecology, restoration, and modeling. ?? Springer 2005.

A deposit model for Mississippi Valley-Type lead-zinc ores: Chapter A in Mineral deposit models for resource assessment

USGS Publications Warehouse

Leach, David L.; Taylor, Ryan D.; Fey, David L.; Diehl, Sharon F.; Saltus, Richard W.

2010-01-01

This report also describes the geoenvironmental characteristic of MVT deposits. The response of MVT ores in the supergene environment is buffered by their placement in carbonate host rocks which commonly results in near-neutral associated drainage water. The geoenvironmental features and anthropogenic mining effects presented in this report illustrates this important environmental aspect of MVT deposits which separates them from other deposit types (especially coal, VHMS, Cu-porphyry, SEDEX, acid-sulfate polymetallic vein).

Depositional evolution of the Lower Khuzestan plain (SW Iran) since the end of the Late Pleistocene

NASA Astrophysics Data System (ADS)

Bogemans, Frieda; Janssens, Rindert; Baeteman, Cecile

2017-09-01

A detailed sedimentological investigation of sixty-six cores supported by radiocarbon age determination enabled the reconstruction of the depositional environmental evolution since the end of the Late Pleistocene in the Iranian part of the Mesopotamian plain. Both fluvial and estuarine environments have been identified on the basis of the sediment characteristics and their between-core stratigraphic correlations. At the end of the Late Pleistocene the fluvial behaviour allowed only the deposition of sand. Prior to 12400-12040 yr cal BP the palaeohydraulics changed by which heterolithic fluvial facies were deposited. Shortly after 12400 - 12040 yr cal BP an erosional phase caused the incision of depressions most probably because of a climate change to further arid conditions. In the early Holocene, mud-dominated river systems filled the depressions; a situation that lasted at least until 7900 - 7700 yr cal BP. After this period tides invaded via the active channels in the downstream part of the area, which turned into an estuarine environment for a period of about 2000-2500 years. Tidal influence diminished and stopped around 5000 yr cal BP because of progradation. Fluvial processes dominated again the sedimentary environment in the study area, except at the southern margin of it where tides controlled, although very locally, the environment.

High-performance integrated virtual environment (HIVE): a robust infrastructure for next-generation sequence data analysis

PubMed Central

Simonyan, Vahan; Chumakov, Konstantin; Dingerdissen, Hayley; Faison, William; Goldweber, Scott; Golikov, Anton; Gulzar, Naila; Karagiannis, Konstantinos; Vinh Nguyen Lam, Phuc; Maudru, Thomas; Muravitskaja, Olesja; Osipova, Ekaterina; Pan, Yang; Pschenichnov, Alexey; Rostovtsev, Alexandre; Santana-Quintero, Luis; Smith, Krista; Thompson, Elaine E.; Tkachenko, Valery; Torcivia-Rodriguez, John; Wan, Quan; Wang, Jing; Wu, Tsung-Jung; Wilson, Carolyn; Mazumder, Raja

2016-01-01

The High-performance Integrated Virtual Environment (HIVE) is a distributed storage and compute environment designed primarily to handle next-generation sequencing (NGS) data. This multicomponent cloud infrastructure provides secure web access for authorized users to deposit, retrieve, annotate and compute on NGS data, and to analyse the outcomes using web interface visual environments appropriately built in collaboration with research and regulatory scientists and other end users. Unlike many massively parallel computing environments, HIVE uses a cloud control server which virtualizes services, not processes. It is both very robust and flexible due to the abstraction layer introduced between computational requests and operating system processes. The novel paradigm of moving computations to the data, instead of moving data to computational nodes, has proven to be significantly less taxing for both hardware and network infrastructure. The honeycomb data model developed for HIVE integrates metadata into an object-oriented model. Its distinction from other object-oriented databases is in the additional implementation of a unified application program interface to search, view and manipulate data of all types. This model simplifies the introduction of new data types, thereby minimizing the need for database restructuring and streamlining the development of new integrated information systems. The honeycomb model employs a highly secure hierarchical access control and permission system, allowing determination of data access privileges in a finely granular manner without flooding the security subsystem with a multiplicity of rules. HIVE infrastructure will allow engineers and scientists to perform NGS analysis in a manner that is both efficient and secure. HIVE is actively supported in public and private domains, and project collaborations are welcomed. Database URL: https://hive.biochemistry.gwu.edu PMID:26989153

High-performance integrated virtual environment (HIVE): a robust infrastructure for next-generation sequence data analysis.

PubMed

Simonyan, Vahan; Chumakov, Konstantin; Dingerdissen, Hayley; Faison, William; Goldweber, Scott; Golikov, Anton; Gulzar, Naila; Karagiannis, Konstantinos; Vinh Nguyen Lam, Phuc; Maudru, Thomas; Muravitskaja, Olesja; Osipova, Ekaterina; Pan, Yang; Pschenichnov, Alexey; Rostovtsev, Alexandre; Santana-Quintero, Luis; Smith, Krista; Thompson, Elaine E; Tkachenko, Valery; Torcivia-Rodriguez, John; Voskanian, Alin; Wan, Quan; Wang, Jing; Wu, Tsung-Jung; Wilson, Carolyn; Mazumder, Raja

2016-01-01

The High-performance Integrated Virtual Environment (HIVE) is a distributed storage and compute environment designed primarily to handle next-generation sequencing (NGS) data. This multicomponent cloud infrastructure provides secure web access for authorized users to deposit, retrieve, annotate and compute on NGS data, and to analyse the outcomes using web interface visual environments appropriately built in collaboration with research and regulatory scientists and other end users. Unlike many massively parallel computing environments, HIVE uses a cloud control server which virtualizes services, not processes. It is both very robust and flexible due to the abstraction layer introduced between computational requests and operating system processes. The novel paradigm of moving computations to the data, instead of moving data to computational nodes, has proven to be significantly less taxing for both hardware and network infrastructure.The honeycomb data model developed for HIVE integrates metadata into an object-oriented model. Its distinction from other object-oriented databases is in the additional implementation of a unified application program interface to search, view and manipulate data of all types. This model simplifies the introduction of new data types, thereby minimizing the need for database restructuring and streamlining the development of new integrated information systems. The honeycomb model employs a highly secure hierarchical access control and permission system, allowing determination of data access privileges in a finely granular manner without flooding the security subsystem with a multiplicity of rules. HIVE infrastructure will allow engineers and scientists to perform NGS analysis in a manner that is both efficient and secure. HIVE is actively supported in public and private domains, and project collaborations are welcomed. Database URL: https://hive.biochemistry.gwu.edu. © The Author(s) 2016. Published by Oxford University Press.

An Appalachian Amazon? Magnetofossil evidence for the development of a tropical river-like system in the mid-Atlantic United States during the Paleocene-Eocene Thermal Maximum

NASA Astrophysics Data System (ADS)

Kopp, R. E.; Schumann, D.; Raub, T. D.; Powars, D. S.; Godfrey, L. V.; Swanson-Hysell, N.; Maloof, A. C.; Vali, H.

2009-12-01

The Paleocene-Eocene Thermal Maximum is preserved within the mid-Atlantic Coastal Plain as a unique clay deposited in the Salisbury Embayment, a tectonic downwarp that stretches from southeastern Virginia to central New Jersey. The mostly massive and kaolinite-rich clay is distinct from the glauconitic sediments that otherwise characterize regional Paleocene and lower Eocene deposits. It contains abundant magnetite produced by magnetotactic bacteria and by larger, presumptively eukaryotic microorganisms not yet known from any other locality. Because most magnetotactic bacteria live within a specific, narrow redox environment -- the suboxic zone of a water column or sediments, where both oxygen and sulfide concentrations are low and iron concentrations relatively high -- their biominerals can be used as a paleoenvironmental tracer. High iron bioavailability indicates a relatively thick suboxic zone. The preservation of iron biominerals suggests that this zone was located in sediments, rather than in the water column, as water column suboxia is associated with high sedimentary organic carbon concentrations, which promote magnetite dissolution. The thickest modern, sedimentary, high-iron suboxic zones occur in tropical river-dominated shelves, such as the Amazon Shelf. These zones result from the combination of a moderately high input of reactive Fe (produced by tropical weathering conditions) with a high-energy environment (produced by tides, frontal-zone currents, and surface waves) that promotes the regular physical reworking of the sediments, thus allowing the re-oxidation of reduced Fe and increasing the availability of Fe as an electron acceptor. To test the "Appalachian Amazon" hypothesis, we mapped the distribution of magnetofossils throughout the Salisbury Embayment using ferromagnetic resonance spectroscopy and electron microscopy, supplemented by organic carbon isotope data. We find three magnetic facies in the clay: Facies 1, characterized by a mix of detrital particles and magnetofossils; Facies 2, with a higher magnetofossil-to-detrital ratio; and Facies 3, with only transient magnetofossils. Facies 1 occurs in inner-middle neritic deposits of central Maryland and northern Virginia, near where the modern Potomac crosses the Fall Line. Facies 2 occurs throughout the middle neritic deposits of eastern Maryland and Virginia and of southern New Jersey. Facies 3 occurs in the outer neritic deposits of eastern New Jersey and on the northern and southern flanks of the embayment. Consistent with the hypothesis, this distribution suggests a link between the magnetofossil distribution and a river system with an outlet in the vicinity of Facies 1. The development of such a river system may have been linked to a combination of more intense weathering, higher precipitation, and increased storminess.

Decadal-scale variations of sedimentary dinoflagellate cyst records from the Yellow Sea over the last 400 years

NASA Astrophysics Data System (ADS)

Kim, So-Young; Roh, Youn Ho; Shin, Hyeon Ho; Huh, Sik; Kang, Sung-Ho; Lim, Dhongil

2018-01-01

In recent decades, the Yellow Sea has experienced severe environmental deterioration due to increasing input of anthropogenic pollutants and consequently accelerated eutrophication. Whilst there have been significant advances in documenting historical records of metal pollution in the Yellow Sea region, changes in phytoplankton community structures affected by eutrophication remain understudied. Here, we present a new record of dinoflagellate cyst-based signals in age-dated sediment cores from the Yellow Sea mud deposits to provide better insight into eutrophication history and identification of associated responses of the regional phytoplankton community. It is worthy of note that there were significant variations in abundances and community structures of dinoflagellate cysts in three historical stages in association with increasing anthropogenic activity over the last 400 years. Pervasive effects of human interference altering the Yellow Sea environments are recognized by: 1) an abrupt increase of organic matter, including the diatom-produced biogenic opal concentrations (∼1850); 2) a distinct shift in phytoplankton composition towards dinoflagellate dominance (∼1940), and 3) recent acceleration of dinoflagellate cyst accumulation (∼1990). Particularly in the central Yellow Sea shelf, the anomalously high deposition of dinoflagellate cysts (especially Alexandrium species) is suggested to be a potentially important source of inoculum cells serving as a seed population for localized and recurrent blooms in coastal areas around the Yellow Sea.

Characterization of a Louisiana Bay Bottom

NASA Astrophysics Data System (ADS)

Freeman, A. M.; Roberts, H. H.

2016-02-01

This study correlates side-scan sonar and CHIRP water bottom-subbottom acoustic amplitudes with cone penetrometer data to expand the limited understanding of the geotechnical properties of sediments in coastal Louisiana's bays. Standardized analysis procedures were developed to characterize the bay bottom and shallow subsurface of the Sister Lake bay bottom. The CHIRP subbottom acoustic data provide relative amplitude information regarding reflection horizons of the bay bottom and shallow subsurface. An amplitude analysis technique was designed to identify different reflectance regions within the lake from the CHIRP subbottom profile data. This amplitude reflectivity analysis technique provides insight into the relative hardness of the bay bottom and shallow subsurface, useful in identifying areas of erosion versus deposition from storms, as well as areas suitable for cultch plants for state oyster seed grounds, or perhaps other restoration projects. Side-scan and CHIRP amplitude reflectivity results are compared to penetrometer data that quantifies geotechnical properties of surface and near-surface sediments. Initial results indicate distinct penetrometer signatures that characterize different substrate areas including soft bottom, storm-deposited silt-rich sediments, oyster cultch, and natural oyster reef areas. Although amplitude analysis of high resolution acoustic data does not directly quantify the geotechnical properties of bottom sediments, our analysis indicates a close relationship. The analysis procedures developed in this study can be applied in other dynamic coastal environments, "calibrating" the use of synoptic acoustic methods for large-scale water bottom characterization.

Microwave-assisted magnesium phosphate coating on the AZ31 magnesium alloy.

PubMed

Ren, Yufu; Babaie, Elham; Lin, Boren; Bhaduri, Sarit B

2017-08-18

Due to the combination of many unique properties, magnesium alloys have been widely recognized as suitable metallic materials for fabricating degradable biomedical implants. However, the extremely high degradation kinetics of magnesium alloys in the physiological environment have hindered their clinical applications. This paper reports for the first time the use of a novel microwave-assisted coating process to deposit magnesium phosphate (MgP) coatings on the Mg alloy AZ31 and improve its in vitro corrosion resistance. Newberyite and trimagnesium phosphate hydrate (TMP) layers with distinct features were fabricated at various processing times and temperatures. Subsequently, the corrosion resistance, degradation behavior, bioactivity and cytocompatibility of the MgP coated AZ31 samples were investigated. The potentiodynamic polarization tests reveal that the corrosion current density of the AZ31 magnesium alloy in simulated body fluid (SBF) is significantly suppressed by the deposited MgP coatings. Additionally, it is seen that MgP coatings remarkably reduced the mass loss of the AZ31 alloy after immersion in SBF for two weeks and promoted precipitation of apatite particles. The high viability of preosteoblast cells cultured with extracts of coated samples indicates that the MgP coatings can improve the cytocompatibility of the AZ31 alloy. These attractive results suggest that MgP coatings, serving as the protective and bioactive layer, can enhance the corrosion resistance and biological response of magnesium alloys.

Lithofacies and seismic-reflection interpretation of temperate glacimarine sedimentation in Tarr Inlet, Glacier Bay, Alaska

USGS Publications Warehouse

Cai, J.; Powell, R.D.; Cowan, E.A.; Carlson, P.R.

1997-01-01

High-resolution seismic-reflection profiles of sediment fill within Tart Inlet of Glacier Bay, Alaska, show seismic facies changes with increasing distance from the glacial termini. Five types of seismic facies are recognized from analysis of Huntec and minisparker records, and seven lithofacies are determined from detailed sedimentologic study of gravity-, vibro- and box-cores, and bottom grab samples. Lithofacies and seismic facies associations, and fjord-floor morphology allow us to divide the fjord into three sedimentary environments: ice-proximal, iceberg-zone and ice-distal. The ice-proximal environment, characterized by a morainal-bank depositional system, can be subdivided into bank-back, bank-core and bank-front subenvironments, each of which is characterized by a different depositional subsystem. A bank-back subsystem shows chaotic seismic facies with a mounded surface, which we infer consists mainly of unsorted diamicton and poorly sorted coarse-grained sediments. A bank-core depositional subsystem is a mixture of diamicton, rubble, gravel, sand and mud. Seismic-reflection records of this subsystem are characterized by chaotic seismic facies with abundant hyperbolic diffractions and a hummocky surface. A bank-front depositional subsystem consists of mainly stratified and massive sand, and is characterized by internal hummocky facies on seismic-reflection records with significant surface relief and sediment gravity flow channels. The depositional system formed in the iceberg-zone environment consists of rhythmically laminated mud interbedded with thin beds of weakly stratified diamicton and stratified or massive sand and silt. On seismic-reflection profiles, this depositional system is characterized by discontinuously stratified facies with multiple channels on the surface in the proximal zone and a single channel on the largely flat sediment surface in the distal zone. The depositional system formed in the ice-distal environment consists of interbedded homogeneous or laminated mud and massive or stratified sand and coarse silt. This depositional system shows continuously stratified seismic facies with smooth and flat surfaces on minisparker records, and continuously stratified seismic facies which are interlayered with thin weakly stratified facies on Huntec records.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Davis, R.J.; Johnson, C.A.; Gilreath, J.A.

Depositional systems in the Medina Group (Lower Silurian) of western New York have been studied using stratigraphic dipmeter data. Results of this study indicate a nearshore-deltaic-interdeltaic depositional environment. Only minor deltaic episodes are preserved in the study area. This fits the generally arid climate with seasonal wet periods suggested by C.D. Laughrey. Facies recognized include: longshore-current sand waves in a shoreface environment, distributary mouth bars, distributary channels, tidal inlets, flood deltas, beaches, sandy tidal flats on which beach ridges were formed, and possible upper delta-plain sediments. Once the depositional sequences are recognized, paleocurrents within key sand units can be interpretedmore » to determine favorable directions for successfully locating offset wells.« less

A note on coarse-grained gravity-flow deposits within proterozoic lacustrine sedimentary rocks, Transvaal sequence, South Africa

NASA Astrophysics Data System (ADS)

Eriksson, P. G.

A widely developed, thin, coarse-matrix conglomerate occurs within early Proterozoic lacustrine mudrocks in the Transvaal Sequence, South Africa. The poorly sorted tabular chert clasts, alternation of a planar clast fabric with disorientated zones, plus normal and inverse grading in the former rock type suggest deposition by density-modified grain-flow and high density turbidity currents. The lower fan-delta slope palæenvironment inferred for the conglomerate is consistent with the lacustrine interpretation for the enclosing mudrock facies. This intracratonic setting contrasts with the marine environment generally associated with density-modified grain-flow deposits.

Process parameter-growth environment-film property relationships for reactive sputter deposited metal (V, Nb, Zr, Y, Au) oxide, nitride, and oxynitride films. Final report, 1 January 1989-30 June 1993

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aita, C.R.

1993-09-30

The research developed process parameter-growth environment-film property relations (phase maps) for model sputter-deposited transition metal oxides, nitrides, and oxynitrides grown by reactive sputter deposition at low temperature. Optical emission spectrometry was used for plasma diagnostics. The results summarized here include the role of sputtered metal-oxygen molecular flux in oxide film growth; structural differences in highest valence oxides including conditions for amorphous growth; and using fundamental optical absorption edge features to probe short range structural disorder. Eight appendices containing sixteen journal articles are included.

Rome in its setting. Post-glacial aggradation history of the Tiber River alluvial deposits and tectonic origin of the Tiber Island

PubMed Central

Motta, Laura; Brock, Andrea L.; Macrì, Patrizia; Florindo, Fabio; Sadori, Laura; Terrenato, Nicola

2018-01-01

The Tiber valley is a prominent feature in the landscape of ancient Rome and an important element for understanding its urban development. However, little is known about the city’s original setting. Our research provides new data on the Holocene sedimentary history and human-environment interactions in the Forum Boarium, the location of the earliest harbor of the city. Since the Last Glacial Maximum, when the fluvial valley was incised to a depth of tens of meters below the present sea level, 14C and ceramic ages coupled with paleomagnetic analysis show the occurrence of three distinct aggradational phases until the establishment of a relatively stable alluvial plain at 6–8 m a.s.l. during the late 3rd century BCE. Moreover, we report evidence of a sudden and anomalous increase in sedimentation rate around 2600 yr BP, leading to the deposition of a 4-6m thick package of alluvial deposits in approximately one century. We discuss this datum in the light of possible tectonic activity along a morpho-structural lineament, revealed by the digital elevation model of this area, crossing the Forum Boarium and aligned with the Tiber Island. We formulate the hypothesis that fault displacement along this structural lineament may be responsible for the sudden collapse of the investigated area, which provided new space for the observed unusually large accumulation of sediments. We also posit that, as a consequence of the diversion of the Tiber course and the loss in capacity of transport by the river, this faulting activity triggered the origin of the Tiber Island. PMID:29590208

Marine intervals in Neogene fluvial deposits of western Amazonia

NASA Astrophysics Data System (ADS)

Boonstra, Melanie; Troelstra, Simon; Lammertsma, Emmy; Hoorn, Carina

2014-05-01

Amazonia is one of the most species rich areas on Earth, but this high diversity is not homogeneous over the entire region. Highest mammal and tree-alpha diversity is found in the fluvio-lacustrine Pebas system, a Neogene wetland associated with rapid radiation of species. The estuarine to marine origin of various modern Amazonian fish, plants, and invertebrates has been associated with past marine ingressions into this freshwater Pebas system. The exact nature and age of these invasions is, however, debated. Here we present new evidence from fluvial and fluvio-lacustrine deposits of Neogene age in southeast Colombia, that point to periods of widespread marine conditions in western Amazonia. Our evidence is based on an analysis of marine palynomorphs, such as organic linings of foraminifera and dinoflagellate cysts, present in dark sandy clay sediments that outcrop along the Caqueta and Amazon rivers. Characteristically, the foraminiferal linings can be assigned to three benthic morphotypes only, e.g. Ammonia, Elphidium and Trochammina. This low diversity assemblage is associated with estuarine/marginal marine conditions. No distinct marine elements such as shelf or planktonic species were encountered. The observed foraminiferal linings and dinocyst assemblages are typical for a (eutrophic) shallow marine environment, suggesting that the Pebas freshwater wetland system occasionally changed to (marginal) marine. Although some reworked elements are found, a typical Neogene dinocyst taxon is commonly found supporting in situ deposition. Sedimentological features typical for tidal conditions that are reported for sites in Peru and northeastern Brazil likely relate to these marine ingressions. Sea level changes as well as foreland basin development related to Andes formation may have facilitated the entry of marine water during the Neogene.

Rome in its setting. Post-glacial aggradation history of the Tiber River alluvial deposits and tectonic origin of the Tiber Island.

PubMed

Marra, Fabrizio; Motta, Laura; Brock, Andrea L; Macrì, Patrizia; Florindo, Fabio; Sadori, Laura; Terrenato, Nicola

2018-01-01

The Tiber valley is a prominent feature in the landscape of ancient Rome and an important element for understanding its urban development. However, little is known about the city's original setting. Our research provides new data on the Holocene sedimentary history and human-environment interactions in the Forum Boarium, the location of the earliest harbor of the city. Since the Last Glacial Maximum, when the fluvial valley was incised to a depth of tens of meters below the present sea level, 14C and ceramic ages coupled with paleomagnetic analysis show the occurrence of three distinct aggradational phases until the establishment of a relatively stable alluvial plain at 6-8 m a.s.l. during the late 3rd century BCE. Moreover, we report evidence of a sudden and anomalous increase in sedimentation rate around 2600 yr BP, leading to the deposition of a 4-6m thick package of alluvial deposits in approximately one century. We discuss this datum in the light of possible tectonic activity along a morpho-structural lineament, revealed by the digital elevation model of this area, crossing the Forum Boarium and aligned with the Tiber Island. We formulate the hypothesis that fault displacement along this structural lineament may be responsible for the sudden collapse of the investigated area, which provided new space for the observed unusually large accumulation of sediments. We also posit that, as a consequence of the diversion of the Tiber course and the loss in capacity of transport by the river, this faulting activity triggered the origin of the Tiber Island.

Bacterial Polymertropism, the Response to Strain-Induced Alignment of Polymers

NASA Astrophysics Data System (ADS)

Lemon, David J.

In nature, bacteria often live in surface-associated communities known as biofilms. Biofilm-forming bacteria deposit a layer of polysaccharide on the surfaces they inhabit; hence, polysaccharide is their immediate environment on any surface. In this study, we examined how the physical characteristics of polysaccharide substrates influence the behavior of the biofilm-forming bacterium Myxococcus xanthus. M. xanthus colonies, and indeed those of the majority of biofilm-forming species tested, respond to the compression-induced deformation of polysaccharide substrates by preferentially spreading across the surface perpendicular to the axis of compression. This response is conserved across multiple distantly related phyla and is found in species with an array of distinct motility apparatuses.The birefringence and small angle X-ray scattering patterns of compressed polysaccharide substrates indicate that the directed surface movements of these bacteria consistently match the orientation of the long axes of aligned and tightly packed polysaccharide fibers in compressed substrates. Therefore, we refer to this behavior as polymertropism to denote that the directed movements are a response to the physical arrangement of the change in packing and alignment of the polymers in the substrate. In addition to altering the colony morphology we find the behavior of groups of cells, called flares, is also affected in several species resulting in increased flare speed, duration, and displacement on compressed gel substrates.We suggest that polymertropism, which requires a downward-facing motility apparatus in M. xanthus, may be responsible for the observed tendency of bacterial cells to follow trails of extruded and presumably aligned polysaccharides, which their neighbors secrete and deposit on the substrate as they move across it. Polymertropism may also play a role in the organization of bacteria in a biofilm, as the iterative process of polysaccharide trail deposition and following is proposed to yield aggregates of cells.

Depositional environments, diagenesis, hydrocarbons: Codell and Juana Lopez members of Carlile shale (upper Cretaceous), Canon City-Raton basins, south-central Colorado

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krutak, P.R.

1989-09-01

Codell and Juana Lopez strata in the Canon City and northern Raton basins comprise a nearshore marine system which was deposited in a series of barrier islands, lagoon fills, tidal deltas, and offshore bars. Codell thicknesses vary but average 6 m (20 ft). Three areally significant Codell paleoenvironments occur: barrier island, lagoonal, and offshore bar. Juana Lopez rocks are thinner, usually less than 1.8 m (6 ft). Five distinctive lithofacies/paleoenvironments occur in the Juana Lopez: (1) a calcarenite or limy sandstone (tidal flat); (2) a sandstone with limonitized borings (offshore bar complex); (3) a shaly to massive sandstone sequence (subaerialmore » beach/dune ); (4) a sandy limestone or biosparite (lagoonal/bay molluscan biostromes); and (5) a sandy shale (offshore bar sequence). These deposits accumulated along a northeastward-trending coast that prograded southeastward in response to a gradual drop in sea level. Petrographic and scanning electron microscopy study reveals the following diagenetic sequence in the Codell Sandstone: (1) modification by authigenic, syntaxial quartz overgrowths; (2) chert cementation; (3) dissolution episodes causing corrosion of quartz, chert, and feldspar; (4) calcite cementation; (5) late-stage limonitization; and, in rare instances, (6) dehydration of limonite to hematite. Diagenetic changes in the Juana Lopez Member involve minor dolomitization, precipitation of calcite rim cement, and limonitic staining. Stratigraphically trapped hydrocarbons occur in bioturbated, relict shelf Codell sandstones in the west-central portion of the Denver basin. Valley-fill( ) Codell sandstones of the northern Denver basin are generally tight but do produce. Juana Lopez calcarenites and fetid biosparities may lack commercial hydrocarbons.« less

Synchronisation of sedimentary records using tephra: A postglacial tephrochronological model for the Chilean Lake District

NASA Astrophysics Data System (ADS)

Fontijn, Karen; Rawson, Harriet; Van Daele, Maarten; Moernaut, Jasper; Abarzúa, Ana M.; Heirman, Katrien; Bertrand, Sébastien; Pyle, David M.; Mather, Tamsin A.; De Batist, Marc; Naranjo, Jose-Antonio; Moreno, Hugo

2016-04-01

Well-characterised tephra horizons deposited in various sedimentary environments provide a means of synchronising sedimentary archives. The use of tephra as a chronological tool is however still widely underutilised in southern Chile and Argentina. In this study we develop a postglacial tephrochronological model for the Chilean Lake District (ca. 38 to 42°S) by integrating terrestrial and lacustrine records. Tephra deposits preserved in lake sediments record discrete events even if they do not correspond to primary fallout. By combining terrestrial with lacustrine records we obtain the most complete tephrostratigraphic record for the area to date. We present glass geochemical and chronological data for key marker horizons that may be used to synchronise sedimentary archives used for palaeoenvironmental, palaeoclimatological and palaeoseismological purposes. Most volcanoes in the studied segment of the Southern Volcanic Zone, between Llaima and Calbuco, have produced at least one regional marker deposit resulting from a large explosive eruption (magnitude ≥ 4), some of which now have a significantly improved age estimate (e.g., the 10.5 ka Llaima Pumice eruption from Llaima volcano). Others, including several units from Puyehue-Cordón Caulle, are newly described here. We also find tephra related to the Cha1 eruption from Chaitén volcano in lake sediments up to 400 km north from source. Several clear marker horizons are now identified that should help refine age model reconstructions for various sedimentary archives. Our chronological model suggests three distinct phases of eruptive activity impacting the area, with an early-to-mid-Holocene period of relative quiescence. Extending our tephrochronological framework further south into Patagonia will allow a more detailed evaluation of the controls on the occurrence and magnitude of explosive eruptions throughout the postglacial.

Diagram of Lake Stratification on Mars

NASA Image and Video Library

2017-06-01

This diagram presents some of the processes and clues related to a long-ago lake on Mars that became stratified, with the shallow water richer in oxidants than deeper water was. The sedimentary rocks deposited within a lake in Mars' Gale Crater more than three billion years ago differ from each other in a pattern that matches what is seen in lakes on Earth. As sediment-bearing water flows into a lake, bedding thickness and particle size progressively decrease as sediment is deposited in deeper and deeper water as seen in examples of thick beds (PIA19074) from shallowest water, thin beds (PIA19075) from deeper water and even thinner beds (PIA19828) from deepest water. At sites on lower Mount Sharp, inside the crater, measurements of chemical and mineral composition by NASA's Curiosity Mars rover reveal a clear correspondence between the physical characteristics of sedimentary rock from different parts of the lake and how strongly oxidized the sediments were. Rocks with textures indicating that the sediments were deposited near the edge of a lake have more strongly oxidized composition than rocks with textures indicating sedimentation in deep water. For example, the iron mineral hematite is more oxidized than the iron mineral magnetite. An explanation for why such chemical stratification occurs in a lake is that the water closer to the surface is more exposed to oxidizing effects of oxygen in the atmosphere and ultraviolet light. On Earth, a stratified lake with a distinct boundary between oxidant-rich shallows and oxidant-poor depths provides a diversity of environments suited to different types of microbes. If Mars has ever hosted microbial live, the stratified lake at Gale Crater may have similarly provided a range of different habitats for life. https://photojournal.jpl.nasa.gov/catalog/PIA21500

Energy Gradients Structure Microbial Communities Across Sediment Horizons in Deep Marine Sediments of the South China Sea

PubMed Central

Graw, Michael F.; D'Angelo, Grace; Borchers, Matthew; Thurber, Andrew R.; Johnson, Joel E.; Zhang, Chuanlun; Liu, Haodong; Colwell, Frederick S.

2018-01-01

The deep marine subsurface is a heterogeneous environment in which the assembly of microbial communities is thought to be controlled by a combination of organic matter deposition, electron acceptor availability, and sedimentology. However, the relative importance of these factors in structuring microbial communities in marine sediments remains unclear. The South China Sea (SCS) experiences significant variability in sedimentation across the basin and features discrete changes in sedimentology as a result of episodic deposition of turbidites and volcanic ashes within lithogenic clays and siliceous or calcareous ooze deposits throughout the basin's history. Deep subsurface microbial communities were recently sampled by the International Ocean Discovery Program (IODP) at three locations in the SCS with sedimentation rates of 5, 12, and 20 cm per thousand years. Here, we used Illumina sequencing of the 16S ribosomal RNA gene to characterize deep subsurface microbial communities from distinct sediment types at these sites. Communities across all sites were dominated by several poorly characterized taxa implicated in organic matter degradation, including Atribacteria, Dehalococcoidia, and Aerophobetes. Sulfate-reducing bacteria comprised only 4% of the community across sulfate-bearing sediments from multiple cores and did not change in abundance in sediments from the methanogenic zone at the site with the lowest sedimentation rate. Microbial communities were significantly structured by sediment age and the availability of sulfate as an electron acceptor in pore waters. However, microbial communities demonstrated no partitioning based on the sediment type they inhabited. These results indicate that microbial communities in the SCS are structured by the availability of electron donors and acceptors rather than sedimentological characteristics. PMID:29696012

Paleoweathering features in the Sergi Formation (Jurassic-Cretaceous), northeastern Brazil, and implications for hydrocarbon exploration

NASA Astrophysics Data System (ADS)

Pierini, Cristina; Mizusaki, Ana M.; Pimentel, Nuno; Faccini, Ubiratan F.; Scherer, Claiton M. S.

2010-03-01

Paleoweathering in the Sergi Formation has been classified and analyzed to ascertain its origin and relationship with stratigraphic evolution. The Sergi Formation belongs to the pre-rift sequence of the Recôncavo Basin (northeastern Brazil) and comprises a complex association of eolian and fluvial sandstones and lacustrine mudstones. This formation can be subdivided into three depositional sequences bounded by regional unconformities. Four paleoweathering types, each one related to a distinct origin, have been described in the Sergi Formation: (1) textural mottling, which is distinguished by alternating rock colors as a result of the iron oxide mobilization within mineral phases that evolved under alternating oxidation (yellowish, brownish and reddish shades) and reduction (grayish or greenish hues) conditions; (2) non-textural mottling, which displays a discoloration pattern that is independent of the original rock texture; (3) carbonate concentrations, usually related to carbonate nodule formation, which display a massive internal structure that reveals their origin through continuous growth or crystallization; and (4) banded carbonates (silicified), associated with the beginning of regular surface formation due to the chemical precipitation of carbonates within lacustrine environments. Both mottling color motifs and carbonate accumulation usually represent groundwater oscillation rather than pedogenesis. Only carbonate intraclasts and banded carbonate (silicified) have their origin ascribed to pedogenesis sensu stricto, although the carbonate intraclasts do not represent soil deposits in situ, but calcretes eroded from areas close to channels, and the banded carbonates (silicified) have strong diagenetic modifications. Therefore, it is reasonable to assume that fluvial and meteoric water have controlled paleoweathering evolution as well as deposition, yet both aspects are ruled by the same mechanisms (relief, sedimentation rate and, above all, climate).

Supercritical bedforms and sedimentary structures from field and core studies, Middle Eocene deep-marine base-of-slope environment, Ainsa Basin, Spanish Pyrenees

NASA Astrophysics Data System (ADS)

Cornard, Pauline; Pickering, Kevin

2017-04-01

In recent years, many researchers have focussed on supercritical- and subcritical-flow deposits using flume-tank experiments (e.g., Cartigny el al., 2011; Postma et al., 2014; Postma and Cartigny, 2014), or from direct observations on presently active deep-water systems (e.g., Hughes et al., 2012). Using outcrop and core examples from a base-of-slope environment in the Middle Eocene Ainsa Basin, Spanish Pyrenees, and with published experimental work, a range of deposits are interpreted as upper-flow regime sedimentary structures. This contribution focusses on the interpretation of several supercritical bedforms (antidunes and chutes-and-pools) observed on the field and upper-flow regime sedimentary structures recognized in cores. The spatial distribution of supercritical-flow deposits obtained from an analysis of field outcrops and core sedimentary logs are evaluated in relation to the depositional environment (channel axis, off-axis, margin and interfan). The frequency distributions of the bed thicknesses are also analysed in relation to supercritical versus subcritical bed-thickness distributions.

Geologic interpretation of geophysical data for the Wadi al Jarir and Al Jurdhawiyah quadrangles, sheets 25/42 C and D, Kingdom of Saudi Arabia

USGS Publications Warehouse

Kleinkopf, M. Dean; Cole, James C.

1983-01-01

Correlation of aeromagnetic data and mineral deposit information provide justification for some prospecting guides. Small granodiorite-porphyry plutons with distinct edge anomalies in Murdama metasediments commonly are associated with copper-gold-bearing quartz veins. Vein orientations in these and most other known deposits in the northeastern Shield cannot be sensibly related to the stress field of the Najd fault system, and are believed to predate the Najd or to have been governed by local factors. Small, weakly magnetic targets such as the Bald al Jimalah West tungsten deposit are not indicated by the regional magnetic data.

Impact Crater Deposits in the Martian Highlands

NASA Technical Reports Server (NTRS)

Mest, S. C.; Crown, D. a.

2005-01-01

The martian highlands of Noachis Terra (20-30 deg S, 20-50 deg E), Tyrrhena Terra (0-30 deg S, 50- 100 deg E) and Terra Cimmeria (0-60 deg S, 120-170 deg E) preserve long and complex histories of degradation, but the relative effects of such factors as fluvial, eolian, and mass wasting processes have not been well constrained. The effects of this degradation are best observed on large (D greater than 10 km) impact craters that characterize the ancient highlands. Some craters exhibit distinct interior deposits, but precise origins of these deposits are enigmatic; infilling may occur by sedimentary (e.g., fluvial, lacustrine, eolian), mass wasting and (or) volcanic processes.

Sand ridges off Sarasota, Florida: A complex facies boundary on a low-energy inner shelf environment

USGS Publications Warehouse

Twichell, D.; Brooks, Gillian L.; Gelfenbaum, G.; Paskevich, V.; Donahue, Brian

2003-01-01

The innermost shelf off Sarasota, Florida was mapped using sidescan-sonar imagery, seismic-reflection profiles, surface sediment samples, and short cores to define the transition between an onshore siliciclastic sand province and an offshore carbonate province and to identify the processes controlling the distribution of these distinctive facies. The transition between these facies is abrupt and closely tied to the morphology of the inner shelf. A series of low-relief nearly shore-normal ridges characterize the inner shelf. Stratigraphically, the ridges are separated from the underlying Pleistocene and Tertiary carbonate strata by the Holocene ravinement surface. While surficial sediment is fine to very-fine siliciclastic sand on the southeastern sides of the ridges and shell hash covers their northwestern sides, the cores of these Holocene deposits are a mixture of both of these facies. Along the southeastern edges of the ridges the facies boundary coincides with the discontinuity that separates the ridge deposits from the underlying strata. The transition from siliciclastic to carbonate sediment on the northwestern sides of the ridges is equally abrupt, but it falls along the crests of the ridges rather than at their edges. Here the facies transition lies within the Holocene deposit, and appears to be the result of sediment reworking by modern processes. This facies distribution primarily appears to result from south-flowing currents generated during winter storms that winnow the fine siliciclastic sediment from the troughs and steeper northwestern sides of the ridges. A coarse shell lag is left armoring the steeper northwestern sides of the ridges, and the fine sediment is deposited on the gentler southeastern sides of the ridges. This pronounced partitioning of the surficial sediment appears to be the result of the siliciclastic sand being winnowed and transported by these currents while the carbonate shell hash falls below the threshold of sediment movement and is left as a lag. The resulting facies boundaries on this low-energy, sediment-starved inner continental shelf are of two origins which both are tied to the remarkably subtle ridge morphology. Along the southeastern sides of the ridges the facies boundary coincides with a stratigraphic discontinuity that separates Holocene from the older deposits while the transition along the northwestern sides of the ridges is within the Holocene deposit and is the result of sediment redistribution by modern processes. ?? 2003 Elsevier B.V. All rights reserved.

The Geology of the Ka'u Desert, Hawaii as a Mars Analog

NASA Astrophysics Data System (ADS)

Craddock, R. A.; Irwin, R. P.; Williams, R.; Swanson, D.; Howard, A. D.; Quantin, C.; Kuzmin, R.; Zimbelman, J. R.

2005-12-01

The Ka'u Desert is located on the western flank of Kilauea volcano on the Big Island of Hawaii. It is a desert because it receives little annual rainfall (about 150 mm/yr) but also because it is subjected to constant outgassing from Kilauea, which creates a harsh, acidic environment. Near the summit of Kilauea the Ka'u Desert is characterized by the Keanakako'i tephra deposit, which is several meters deep thinning out to a discontinuous deposit 1.5 km (1 mile) towards the center of the desert. The deposit itself has been incised by a number of gullies that are flat-floored and terminate in a series of amphitheater-shaped plunge pools. Most of the interior desert contains undulating weathered lava flows, extensive deposits of sand, and several more recent lava flows and volcanic edifices. The southern portion of the desert is bounded by the Hilina Pali fault scarp, which is 500 m (1,500 ft) above the nearby Pacific Ocean and contains a complex series of outwash plains, alluvial fans, and debris flows. We will present a summary of the geology of the Ka'u Desert. Contrary to published interpretations, we will present evidence that the Keanakako'i was not emplaced by two separate catastrophic eruption events but rather by two distinct eruption episodes that included multiple eruption events often interrupted by long hiatuses. Despite the morphology of the gullies contained on the Keanakako'i we will present evidence that the gullies were formed exclusively by surface runoff and not groundwater sapping, including quantitative estimates about the large amounts of discharge that occur during extreme storms. We will also present analyses of the sand deposits and determine the likely provenance of these materials. For the first time, we will also describe alluvial fans and mass wasting features on Hilina Pali and show evidence that they are part of poorly integrated channel system that originates in the Keanakako'i tephra. The Ka'u Desert represents a good Mars analog because (1) similar to valley networks, the development of channels and gullies in the Ka'u Desert has been interrupted by resurfacing events, (2) associated fluvial deposits have been heavily modified by eolian processes, and (3) the alluvial fans on the Hilina Pali have unusually large source areas.

A colluvium - travertine sedimentary succession from the Tibetan Plateau: dating and climatic significance

NASA Astrophysics Data System (ADS)

Meyer, Michael; Wang, Zhijun; Schlütz, Frank; Hoffmann, Dirk; May, Jan-Hendrik; Aldenderfer, Mark

2014-05-01

Morphodynamics and sedimentation on the Tibetan Plateau are strongly controlled by cold-arid climate conditions and distinct freeze-thaw cycles. In such a periglacial environment mass-wasting processes are dominant on mountain slopes, causing thick successions of talus and colluvium to accumulate. While periglacial slope dynamics are ubiquitous on the plateau today, they were probably much more intense during the various cold stages of the Late Pleistocene. However, the exact nature as well as the timing and duration of such temperature controlled slope dynamics on the Tibetan plateau are not well constrained. Travertines are secondary carbonates precipitated from hydrothermal springs. On the Tibetan Plateau these types of spring deposits form along neotectonic faults, where super-saturated ground water can penetrate onto the surface, facilitating degassing and carbonate precipitation. Spring carbonate formation further requires non-permanently frozen ground and reasonable humid conditions in order to recharge the ground water aquifer. Travertines hold potential for palaeoenvironmental reconstruction, because they are dateable via U-series techniques and their geochemical, biological and petrographic signature can be used to extract high resolution palaeoenvironmental information. Due to a dense network of neotectonic faults on the Tibetan plateau, travertines are relatively common. Nevertheless, the potential of these hydrothermal spring deposits as an archive for palaeoenvironmental change on the plateau has yet to be explored. Here we present the first results obtained for an unusual, non-continuous sediment sequence encountered in southern Tibet at an altitude of 4200 m asl. near Chusang village, i.e. a ca. 200 m thick succession of periglacial colluvium alternating with travertine deposits. Preliminary data indicate that travertine deposition at the Chusang hydrothermal spring occurred periodically throughout the Late Pleistocene and extensive travertine precipitation was also responsible for preserving old colluvial sediment. We combine U-series disequilibrium dating with optically stimulated luminescence dating and radiocarbon dating to constrain the depositional history of this unique sediment sequence. Sedimentological logging and geomorphological mapping is used to understand past depositional processes and environmental constraints. Comparison to published high resolution climate records that are continuous in nature (e.g. speleothem records from adjacent catchments and regions) will allow us to link this clastic-chemical sediment sequence into the broader palaeoclimatic framework of High Asia.

Characterization of solid airborne particles deposited in snow in the vicinity of urban fossil fuel thermal power plant (Western Siberia).

PubMed

Talovskaya, A V; Yazikov, E G; Filimonenko, E A; Lata, J-C; Kim, J; Shakhova, T S

2017-07-20

Recognition and detailed characterization of solid particles emitted from thermal power plants into the environment is highly important due to their potential detrimental effects on human health. Snow cover is used for the identification of anthropogenic emissions in the environment. However, little is known about types, physical and chemical properties of solid airborne particles (SAP) deposited in snow around thermal power plants. The purpose of this study is to quantify and characterize in detail the traceable SAP deposited in snow near fossil fuel thermal power plant in order to identify its emissions into the environment. Applying the scanning electron microscopy-energy dispersive spectroscopy, and X-ray diffraction, mineral and anthropogenic phase groups in SAP deposited in snow near the plant and in fly ash were observed. We identified quartz, albite and mullite as most abundant mineral phases and carbonaceous matter, slag and spherical particles as dominate anthropogenic phases. This is the first study reporting that zircon and anthropogenic sulphide-bearing, metal oxide-bearing, intermetallic compound-bearing and rare-earth element-bearing particles were detected in snow deposits near thermal power plant. The identified mineral and anthropogenic phases can be used as tracers for fossil fuel combustion emissions, especially with regard to their possible effect on human health.

Ants adjust their pheromone deposition to a changing environment and their probability of making errors.

PubMed

Czaczkes, Tomer J; Heinze, Jürgen

2015-07-07

Animals must contend with an ever-changing environment. Social animals, especially eusocial insects such as ants and bees, rely heavily on communication for their success. However, in a changing environment, communicated information can become rapidly outdated. This is a particular problem for pheromone trail using ants, as once deposited pheromones cannot be removed. Here, we study the response of ant foragers to an environmental change. Ants were trained to one feeder location, and the feeder was then moved to a different location. We found that ants responded to an environmental change by strongly upregulating pheromone deposition immediately after experiencing the change. This may help maintain the colony's foraging flexibility, and allow multiple food locations to be exploited simultaneously. Our treatment also caused uncertainty in the foragers, by making their memories less reliable. Ants which had made an error but eventually found the food source upregulated pheromone deposition when returning to the nest. Intriguingly, ants on their way towards the food source downregulated pheromone deposition if they were going to make an error. This may suggest that individual ants can measure the reliability of their own memories and respond appropriately. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Significance of nearshore trace-fossil assemblages of the cambro-ordovician deadwood formation and Aladdin Sandstone, South Dakota

USGS Publications Warehouse

Stanley, T.M.; Feldmann, R.M.

1998-01-01

The Cambro-Ordovician Deadwood Formation and Aladdin Sandstone represent intertidal and subtidal, nearshore deposystems that contain few well-preserved body fossils, but contain abundant trace fossils. The present study uses the much neglected trace-fossil fauna to describe the diverse paleoenvironments represented in the Deadwood-Aladdin deposystems, and to better understand the environmental conditions that controlled benthic life in the Early Paleozoic. The Deadwood-Aladdin ichnotaxa can be separated into three distinct assemblages based on the changing sedimentologic and hydrodynamic conditions that existed across the Cambro-Ordovician shelf. Trace-fossil assemblages and corresponding lithofacies characteristics indicate that the Deadwood-Aladdin deposystems formed within an intertidal-flat and subtidal-shelf environment. Based on the distribution and numbers of preserved ichnotaxa, the intertidal flat can be subdivided further into an ecologically stressful inner sand-flat environment, and a more normal marine outer sand-flat environment, both of which belong to a mixed, Skolithos-Cruziana softground ichnofacies. The inner sand flat is characterized by low diversity, low numbers, and a general lack of complexly constructed ichnotaxa. Trace fossils common to both assemblages tend to be smaller in the inner flat compared to the outer sand flat. Taphonomic effects, such as substrate type and sediment heterogeneity, also aid in differentiating between the inner and outer sand-flat assemblages. The subtidal shelf environment is categorized in the Cruziana Ichnofacies. Ichnological evidence of periodic tempestite deposition and hardground development within this subtidal regime is manifested by high diversity and low abundance of ichnogenera.

Occurrence model for volcanogenic beryllium deposits: Chapter F in Mineral deposit models for resource assessment

USGS Publications Warehouse

Foley, Nora K.; Hofstra, Albert H.; Lindsey, David A.; Seal, Robert R.; Jaskula, Brian W.; Piatak, Nadine M.

2012-01-01

Current global and domestic mineral resources of beryllium (Be) for industrial uses are dominated by ores produced from deposits of the volcanogenic Be type. Beryllium deposits of this type can form where hydrothermal fluids interact with fluorine and lithophile-element (uranium, thorium, rubidium, lithium, beryllium, cesium, tantalum, rare earth elements, and tin) enriched volcanic rocks that contain a highly reactive lithic component, such as carbonate clasts. Volcanic and hypabyssal high-silica biotite-bearing topaz rhyolite constitutes the most well-recognized igneous suite associated with such Be deposits. The exemplar setting is an extensional tectonic environment, such as that characterized by the Basin and Range Province, where younger topaz-bearing igneous rock sequences overlie older dolomite, quartzite, shale, and limestone sequences. Mined deposits and related mineralized rocks at Spor Mountain, Utah, make up a unique economic deposit of volcanogenic Be having extensive production and proven and probable reserves. Proven reserves in Utah, as reported by the U.S. Geological Survey National Mineral Information Center, total about 15,900 tons of Be that are present in the mineral bertrandite (Be4Si2O7(OH)2). At the type locality for volcanogenic Be, Spor Mountain, the tuffaceous breccias and stratified tuffs that host the Be ore formed as a result of explosive volcanism that brought carbonate and other lithic fragments to the surface through vent structures that cut the underlying dolomitic Paleozoic sedimentary rock sequences. The tuffaceous sediments and lithic clasts are thought to make up phreatomagmatic base surge deposits. Hydrothermal fluids leached Be from volcanic glass in the tuff and redeposited the Be as bertrandite upon reaction of the hydrothermal fluid with carbonate clasts in lithic-rich sections of tuff. The localization of the deposits in tuff above fluorite-mineralized faults in carbonate rocks, together with isotopic evidence for the involvement of magmatic water in an otherwise meteoric water-dominated hydrothermal system, indicate that magmatic volatiles contributed to mineralization. At the type locality, hydrothermal alteration of dolomite clasts formed layered nodules of calcite, opal, fluorite, and bertrandite, the latter occurring finely intergrown with fluorite. Alteration assemblages and elemental enrichments in the tuff and surrounding volcanic rocks include regional diagenetic clays and potassium feldspar and distinctive hydrothermal halos of anomalous fluorine, lithium, molybdenum, niobium, tin, and tantalum, and intense potassium feldspathization with sericite and lithium-smectite in the immediate vicinity of Be ore. Formation of volcanogenic Be deposits is due to the coincidence of multiple factors that include an appropriate Be-bearing source rock, a subjacent pluton that supplied volatiles and heat to drive convection of meteoric groundwater, a depositional site characterized by the intersection of normal faults with permeable tuff below a less permeable cap rock, a fluorine-rich ore fluid that facilitated Be transport (for example, BeF42- complex), and the existence of a chemical trap that caused fluorite and bertrandite to precipitate at the former site of carbonate lithic clasts in the tuff.

Depositional processes in large-scale debris-flow experiments

USGS Publications Warehouse

Major, J.J.

1997-01-01

This study examines the depositional process and characteristics of deposits of large-scale experimental debris flows (to 15 m3) composed of mixtures of gravel (to 32 mm), sand, and mud. The experiments were performed using a 95-m-long, 2-m-wide debris-flow flume that slopes 31??. Following release, experimental debris flows invariably developed numerous shallow (???10 cm deep) surges. Sediment transported by surges accumulated abruptly on a 3?? runout slope at the mouth of the flume. Deposits developed in a complex manner through a combination of shoving forward and shouldering aside previously deposited debris and through progressive vertical accretion. Progressive accretion by the experimental flows is contrary to commonly assumed en masse sedimentation by debris flows. Despite progressive sediment emplacement, deposits were composed of unstratified accumulations of generally unsorted debris; hence massively textured, poorly sorted debris-flow deposits are not emplaced uniquely en masse. The depositional process was recorded mainly by deposit morphology and surface texture and was not faithfully registered by interior sedimentary texture; homogeneous internal textures could be misinterpreted as the result of en masse emplacement by a single surge. Deposition of sediment by similar, yet separate, debris flows produced a homogenous, massively textured composite deposit having little stratigraphic distinction. Similar deposit characteristics and textures are observed in natural debris-flow deposits. Experimental production of massively textured deposits by progressive sediment accretion limits interpretations that can be drawn from deposit characteristics and casts doubt on methods of estimating flow properties from deposit thickness or from relations between particle size and bed thickness.

Geochemical characteristics of The Emet (Espey-Hisarcik) borate deposits, Kütahya, Turkey

NASA Astrophysics Data System (ADS)

Koçak, İ.; Koç, Ş.

2018-06-01

Nearly 72% world's borate reserves are in western part of Turkey. The Emet (Kütahya) deposit is one of these deposits. The Emet borate deposit, like other deposits in western Anatolia, was deposited in Miocene lacustrine environment whose formation coincides with volcanic activity started in Paleogene and lasted to the beginning of Quaternary. The borate ore displaying lenticular structure is alternated with claystone, marl, tuff and thin bedded limestone. The mineral paragenesis is composed of colemanite, hydroboracite, Veatchite, dolomite, calcite, montmorillonite and illite. The Emet borate deposit has been the subject of various geologic and mineralogical studies. In the present study major and trace element contents of 60 borate samples from this deposit are discussed. Among the trace elements, significant enrichment was found in As, Se, Sr, Cs, Sb and Li. Element correlations indicate volcanic source for boron (exhalations and hydrothermal solutions) whilst other elements are found to be derived from a terrestrial source. According to REE data, high Ce concentrations and anomalies are generally indicative of oxygenated depositional environment whilst low Ce contents facilitated the lake waters to be low oxygenated as a result of H2S-rich hydrothermal solutions. The weak negative anomaly detected only in the Hisarcık region is attributed to lacking of Eu contribution to the lake due to insufficient alteration on the continent.

Loess records

USGS Publications Warehouse

Muhs, Daniel R.; Cattle, Stephen R.; Crouvi, Onn; Rousseau, Denis-Didier; Sun, Jiimin; Zárate, Marcelo A.

2014-01-01

Loess is aeolian sediment, dominated by silt-sized particles, that is identifiable in the field as a distinct sedimentary body. It covers a significant portion of the land surface of the Earth and as such constitutes one of the most important archives of long-term dust deposition. Large tracts of loess cover Europe, Asia, South America, and North America, and smaller loess bodies are found covering parts of Africa, the Middle East, New Zealand, and Australia. Loess thickness, particle size, and carbonate content decrease downwind from sources, trends that are powerful tools for reconstructing paleowinds. Many loess sections consist of relatively thick deposits of mostly unaltered sediment with intercalated paleosols. Paleosols represent periods of landscape stability when loess deposition ceased or at least slowed significantly. Studies from several continents show that loess in most regions was deposited during glacial periods and paleosols formed during interglacial and interstadial periods.

Origin of a classic cratonic sheet sandstone: Stratigraphy across the Sauk II-Sauk III boundary in the Upper Mississippi Valley

USGS Publications Warehouse

Runkel, Anthony C.; McKay, R.M.; Palmer, A.R.

1998-01-01

The origin of cratonic sheet sandstones of Proterozoic and early Paleozoic age has been a long-standing problem for sedimentologists. Lower Paleozoic strata in the Upper Mississippi Valley are best known for several such sandstone bodies, the regional depositional histories of which are poorly understood. We have combined outcrop and subsurface data from six states to place the Upper Cambrian Wonewoc (Ironton and Galesville) Sandstone in a well-constrained stratigraphic framework across thousands of square kilometers. This framework makes it possible for the first time to construct a regional-scale depositional model that explains the origin of this and other cratonic sheet sandstones. The Wonewoc Sandstone, although mapped as a single contiguous sheet, is a stratigraphically complex unit that was deposited during three distinct conditions of relative sea level that span parts of four trilobite zones. During a relative highstand of sea level in Crepicephalus Zone time, quartzose sandstone lithofacies aggraded more or less vertically in nearshore-marine and terrestrial environments across much of the present-day out-crop belt around the Wisconsin arch. At the same time, finer grained, feldspathic sandstone, siltstone, and shale aggraded in deeper water immediately seaward of the quartzose sand, and shale and carbonate sediment accumulated in the most distal areas. During Aphelaspis and Dunderbergia Zones time a relative fall in sea level led to the dispersal of quartzose sand into a basinward-tapering, sheet-like body across much of the Upper Mississippi Valley. During early Elvinia Zone time a major transgression led to deposition of a second sheet sandstone that is generally similar to the underlying regressive sheet. The results of this investigation also demonstrate how subtle sequence-bounding unconformities may be recognized in mature, cratonic siliciclastics. We place the Sauk II-Sauk III subsequence boundary at the base of the coarsest bed in the Wonewoc Sandstone, a lag developed through erosion that occurred during the regional regressive-transgressive event that spanned Aphelaspis to early Elvinia Zones time. Such sequence-bounding unconformities are difficult to recognize where they are contained within coarse siliciclastics of the Upper Mississippi Valley, because they separate strata that are texturally and mineralogically similar, and because erosion occurred on a loose, sandy substrate along a low, uniform gradient, and in a nonvegetated terrestrial environment. Furthermore, the ultramature mineral composition of the exposed substrate is resistant to the development of a recognizable weathering profile. The well-known sheet geometry of the Wonewoc and other units of lower Paleozoic sandstone of this area is not dependent on atypical terrestrial depositional conditions conducive to the widespread distribution of sand, as commonly believed. Sand was spread into a sheet dominantly within the marine realm in a manner similar to that inferred for many better-known sandstone bodies deposited in the North American Cretaceous Western Interior seaway and Tertiary Gulf of Mexico. The laterally extensive, thin character of the Upper Mississippi Valley sandstone bodies compared to these other sandstone bodies simply reflects deposition of a continuously abundant supply of sand on a relatively stable, nearly flat basin of slow, uniform subsidence during changes in sea level. The dearth of shale in this and other cratonic sandstones can be indirectly attributed to the same controls, which led to an uncommonly low preservation potential for fairweather deposits on the shoreface.

Ancient and modern sites of natural CO2 leakage: Geochemistry and geochronology of Quaternary and modern travertine deposits on the Colorado Plateau, USA, and implications for CO2 sequestration

NASA Astrophysics Data System (ADS)

Priewisch, A.; Crossey, L. J.; Karlstrom, K. E.; McPherson, B. J.; Mozley, P.

2013-12-01

Travertine-precipitating springs and travertine deposits of the Colorado Plateau serve as natural analogues for evaluating potential leakage associated with geologic sequestration of carbon dioxide (CO2). Extensive Quaternary and modern travertine deposits occur along the Jemez lineament and Rio Grande rift in New Mexico and Arizona, and in the Paradox Basin in Utah, along the Little Grand Wash Fault and the Salt Wash Graben. These groundwater discharge deposits are interpreted to be sites of persistent and significant CO2 degassing along faults and above magmatic systems. Analysis of the geochemical and isotopic composition of U-series dated travertine deposits and modern travertine-precipitating waters allows evaluation of the flow paths of CO2-charged waters. Initial results from New Mexico and Arizona travertine deposits show characteristic rare earth element (REE) signatures for individual travertine deposits and yet generally overlap in concentrations of other trace elements such as Al, As, B, Ba, K, and Si. We report stable oxygen and carbon isotopes of the travertines in New Mexico, Arizona, and Utah. Different travertine deposits have different carbon-oxygen isotope variation patterns suggesting that these stable isotopes are tracers that have the ability to identify distinctive groundwater sources within and between spring groups based on the travertine record. Stable isotope analyses of travertine deposits in New Mexico and Arizona overlap substantially between deposits and cluster around -10‰ to -6‰ for δ18O and around 3.5‰ to 6.5‰ for δ13C. Travertine deposits in Utah show a distinctly different range of stable isotope values: δ18O values cluster around -14‰ to -10.5‰ and δ13C around 4.5‰ to 6.5‰. U-series dating of travertine deposits shows episodic travertine formation in New Mexico and Arizona over the last 700,000 years, and travertine accumulation over the last 400,000 years in Utah. We use U-series dating and volumetric analysis of the travertine deposits to estimate the minimum CO2 flux that was necessary to form the deposits and compare it to modern flux measurements in order to assess the extent of former and modern CO2 leakage. In addition, the thickness of dated travertine sections provides information about the longevity of travertine mound or spring systems that may be controlled by, e. g., sealing of faults, alternating wet/ dry paleohydrologic conditions, and/or rates of magmatic CO2 supply to springs. Understanding travertine deposition is important for the assessment of the long-term performance of a potential CO2 sequestration site because travertine deposits give insight into the complexities of CO2 pathways and leakage rates over timescales necessary for CO2 sequestration.

Tracing sources of crustal contamination using multiple S and Fe isotopes in the Hart komatiite-associated Ni-Cu-PGE sulfide deposit, Abitibi greenstone belt, Ontario, Canada

NASA Astrophysics Data System (ADS)

Hiebert, R. S.; Bekker, A.; Houlé, M. G.; Wing, B. A.; Rouxel, O. J.

2016-10-01

Assimilation by mafic to ultramafic magmas of sulfur-bearing country rocks is considered an important contributing factor to reach sulfide saturation and form magmatic Ni-Cu-platinum group element (PGE) sulfide deposits. Sulfur-bearing sedimentary rocks in the Archean are generally characterized by mass-independent fractionation of sulfur isotopes that is a result of atmospheric photochemical reactions, which produces isotopically distinct pools of sulfur. Likewise, low-temperature processing of iron, through biological and abiotic redox cycling, produces a range of Fe isotope values in Archean sedimentary rocks that is distinct from the range of the mantle and magmatic Fe isotope values. Both of these signals can be used to identify potential country rock assimilants and their contribution to magmatic sulfide deposits. We use multiple S and Fe isotopes to characterize the composition of the potential iron and sulfur sources for the sulfide liquids that formed the Hart deposit in the Shaw Dome area within the Abitibi greenstone belt in Ontario (Canada). The Hart deposit is composed of two zones with komatiite-associated Ni-Cu-PGE mineralization; the main zone consists of a massive sulfide deposit at the base of the basal flow in the komatiite sequence, whereas the eastern extension consists of a semi-massive sulfide zone located 12 to 25 m above the base of the second flow in the komatiite sequence. Low δ56Fe values and non-zero δ34S and Δ33S values of the komatiitic rocks and associated mineralization at the Hart deposit is best explained by mixing and isotope exchange with crustal materials, such as exhalite and graphitic argillite, rather than intrinsic fractionation within the komatiite. This approach allows tracing the extent of crustal contamination away from the deposit and the degree of mixing between the sulfide and komatiite melts. The exhalite and graphitic argillite were the dominant contaminants for the main zone of mineralization and the eastern extension zone of the Hart deposit, respectively. Critically, the extent of contamination, as revealed by multiple S and Fe isotope systematics, is greatest within the deposit and decreases away from it within the komatiite flow. This pattern points to a local source of crustal contamination for the mantle-derived komatiitic melt and a low degree of homogenization between the mineralization and the surrounding lava flow. Coupled S and Fe isotope patterns like those identified at the Hart deposit may provide a useful tool for assessing the potential of a komatiitic sequence to host Ni-Cu-(PGE).

Suspected Offshore Chalcolithic/Early Bronze Age Tsunamigenic Sediments: Jisr al Zarka, Israel

NASA Astrophysics Data System (ADS)

Tiulienieva, N.; Braun, Y.; Katz, T.; Goodman-Tchernov, B. N.; Suchkov, I.

2017-12-01

Offshore tsunami deposits are a potentially important sedimentological archive for past tsunamis. They have been identified offshore of Israel using granulometric, geoarchaeological, and micropaleontological indicators. Recent advances in tsunami sedimentological research have put forth a series of new proxies that may be useful tools for tsunami deposit identification. The well-studied offshore deposits of Israel provide a unique opportunity to test some of these proxies because they present good distinction between tsunami and non-tsunami deposits and they can be associated with a rich historical record and archaeological artifacts. In this study, a 219 cm long sediment core, retrieved from a 15.3 m water depth, situated in about 5 km to the north from well studied shallow shelf, offshore Caesarea. Based on the previously used criteria three layers in the new core were identified as tsunami-generated. Two of these correlated to previously described tsunami events in Caesarea; 749 AD and 1500 BC. The third layer gave the time frame from 5.6 to 6 ka BP, making this event the oldest identified in the Eastern Mediterranean to date. Identified unusual layers were attributed to tsunami-generated sedimentary sequences, based on both visually recognizable indicators and the results of laboratory analyses. FT-IR, XRD, and XRF analysis were also applied. The results of this study allow to make following conclusions: (1) visual tsunami indicators in the studied core are similar to those in Caesarea, but lack archaeological debris; (2) while distinct deviation of granulometric coefficients (mean, median, standard deviation, skewness, kurtosis) correlated to tsunami layers, the additional proxies of deposition rate and mollusk assemblage excluded one deviated layer from tsunamigenic-designation; (3) the results of XRF, FT-IR, XRD showed that they are not useful as independent methods at this study site.

The Lacustrine Upper Brushy Basin Member of the Morrison Formation, Four Corners Region, Usa: a Lithological and Mineralogical Terrestrial Analog for Gale Crater, Mars

NASA Astrophysics Data System (ADS)

Potter-McIntyre, S. L.; Chan, M. A.; McPherson, B. J.

2013-12-01

The upper part of the Jurassic Brushy Basin Member of the Morrison Formation is an iron- and clay-rich volcaniclastic shale deposited in an ephemeral alkaline saline lake system. Sedimentary rocks exposed in Gale Crater consist of similar non-acidic clays, possibly of lacustrine origin. Three primary clastic lithofacies are present in both the Brushy Basin Member and at Gale Crater: silt-/claystone, sandstone, and conglomerate. Both the terrestrial and martian silt-/claystone lithofacies are interpreted as lacustrine depositional environments due to features such as parallel laminated and massive sedimentary structures. Vugs are present in the siltstone/claystone facies on both the Colorado Plateau and at Gale Crater. Fluvial features are also observed in both examples such as cross-bedded sandstones and imbricated conglomerates. Concretions are present in both the Colorado Plateau and Gale Crater units. The vugs in the Brushy Basin Member preserve algal forms with cellular elaboration and are interpreted as charophyte molds. Two distinct suites of elements (1. C, Fe, As, P and, 2. C, S, Se, P) are associated with the microbial fossils and may be potential markers for biosignatures. Vugs at Gale Crater are a potential target to investigate the possibility of preserved microbial (algal) life where early analyses show the presence of the elements capable of supporting life. The Brushy Basin Member is composed predominately of quartz, feldspars, zeolites and altered volcanic ash. The abundant clay minerals in both the terrestrial and martian examples are hypothesized to have formed due to partial alteration of volcanic minerals in alkaline fluid. Similarly, concretions present in the terrestrial unit exhibit a diverse range of mineralogies likely due to alkaline fluid chemistries interacting with reactive volcaniclastic sediments. Terrestrial concretion mineralogy is diverse even within an outcrop or stratigraphic horizon which suggests reactants to precipitate concretions are being sourced from diagenetic micorenvironments. Similar diagenetic microenvironments may be preserved at Gale Crater due to the fine-grained, volcaniclastic (reactive) rocks. The Brushy Basin Member is a valuable analog because comparative iron-and clay-rich compositions help to: 1) understand diagenetic processes in a non-acidic, saline lacustrine environment, 2) document specific sedimentary structures and lithofacies associations to interpret depositional environment, 3) document specific biomediated features (e.g., textures, morphologies, chemistries), and 4) demonstrate how these features might persist or respond to diagenesis over time.

Descriptions and preliminary report on sediment cores from the southwest coastal area, Everglades National Park, Florida

USGS Publications Warehouse

Wingard, G. Lynn; Cronin, Thomas M.; Holmes, Charles W.; Willard, Debra A.; Budet, Carlos A.; Ortiz, Ruth E.

2005-01-01

Sediment cores were collected from five locations in the southwest coastal area of Everglades National Park, Florida, in May 2004 for the purpose of determining the ecosystem history of the area and the impacts of changes in flow through the Shark River Slough. An understanding of natural cycles of change prior to significant human disturbance allows land managers to set realistic performance measures and targets for salinity and other water quality and quantity quality measures. Preliminary examination of the cores indicates significant changes have taken place over the last 1000-2000 years. The cores collected from the inner bays - the most landward bays - are distinctly different from other estuarine sediment cores examined in Florida Bay and Biscayne Bay. Peats in the inner-bay cores from Big Lostmans Bay, Broad River Bay, and Tarpon Bay were deposited at least 1000 years before present (BP) based on radiocarbon analyses. The peats are overlain by poorly sorted organic muds and sands containing species indicative of deposition in a freshwater to very low salinity environment. The Alligator Bay core, the most northern inner-bay core, is almost entirely sand; no detailed faunal analyses or radiometric dating has been completed on this core. The Roberts River core, taken from the mouth of the River where it empties into Whitewater Bay, is lithologically and faunally similar to previously examined cores from Biscayne and Florida Bays; however, the basal unit was deposited ~2000 years before the present based on radiocarbon analyses. A definite trend of increasing salinity over time is seen in the Roberts River core, from sediments representing a terrestrially dominated freshwater environment at the bottom of the core to those representing an estuarine environment with a strong freshwater influence at the top. The changes seen at Roberts River could represent a combination of factors including rising sea-level and changes in freshwater supply, but the timing and extent of the changes needs to be determined. The preliminary information on the cores collected in 2004 will be combined with data from cores collected in July 2005. The 2005 cores were collected along transects moving from the inner bays out towards the coast. These transects, combining information from the 2004 and 2005 cores, will allow us to examine long term trends in freshwater supply, sea-level rise, and potentially the impact of storms on the coastal ecosystem.

Interstratified arkosic and volcanic rocks of the Miocene Spanish Canyon Formation, Alvord Mountain area, California: descriptions and interpretations

USGS Publications Warehouse

Buesch, David C.

2014-01-01

The Spanish Canyon Foundation in the Alvord Mountain area, California, varies from about 50 to 120 m thick and records the interstratification of arkosic sandstone and conglomerate with tuffaceous deposits and lava flows. In the lower third of the formation, arkosic sandstone and conglomerate are interstratified with tuffaceous deposits. Some tuffs might have been deposited as primary, nonwelded to partially welded ignimbrites or fallout tephra. Many of the tuffaceous deposits represent redeposited material that formed tuffaceous sandstone, and many of these deposits contain arkosic grains that represent mixing of different source matieral. Arkosic sandstone, and especially conglomerate (some with maximum clast lengths up to 1 m), represent intermittent incursions of coarser plutoniclastic fan deposits into other finer grained and mostly volcaniclastic basin deposits. After deposition of the 18.78 Ma Peach Spring Tuff, the amount of tuffaceous material decreased. The upper two-thirds of the formation has arkosic sandstone and conglomerate interstratified with two olivine basalt lave flows. locally, conglomerate clasts in this part of the section have maximum lengths up to 1 m. Many tuffaceous and arkosic sandstone beds of the Spanish Canyon Formation have tabular to broad (low-relief) lenticular geometry, and locally, some arkosic conglomerate fills channels as much as 1.5 m deep. These bedforms are consistent with deposition in medial to distal alluvial-fan or fluvial environments; some finer-grained deposits might have formed in lacustrine environments.

Publications - MP 158 | Alaska Division of Geological & Geophysical Surveys

Science.gov Websites

Portal Climate and Cryosphere Hazards Coastal Hazards Program Guide to Geologic Hazards in Alaska Deposits; Bluff; Coastal; Coastal Erosion; Depositional Environment; Dunes; Engineering Geology; Flood

Stratigraphy of a proposed wind farm site southeast of Block Island: Utilization of borehole samples, downhole logging, and seismic profiles

NASA Astrophysics Data System (ADS)

Sheldon, Dane P. H.

Seismic stratigraphy, sedimentology, lithostratigraphy, downhole geophysical logging, mineralogy, and palynology were used to study and interpret the upper 70 meters of the inner continental shelf sediments within a proposed wind farm site located approximately two to three nautical miles to the southeast of Block Island, Rhode Island. Core samples and downhole logging collected from borings drilled for geotechnical purposes at proposed wind turbine sites along with seismic surveys in the surrounding area provide the data for this study. Cretaceous coastal plain sediments that consist of non-marine to marine sand, silt, and clay are found overlying bedrock at a contact depth beyond the sampling depth of this study. The upper Cretaceous sediments sampled in borings are correlated with the Magothy/Matawan formations described regionally from New Jersey to Nantucket. An unconformity formed through sub-aerial, fluvial, marine, and glacial erosion marks the upper strata of the Cretaceous sediments separating them from the overlying deposits. The majority of Quaternary deposits overlying the unconformity represent the advance, pulsing, and retreat of the Laurentide ice sheet that reached its southern terminus in the area of Block Island approximately 25,000 to 21,000 years before present. The sequence consists of a basal glacial till overlain by sediments deposited by meltwater environments ranging from deltaic to proglacial lakefloor. A late Pleistocene to early Holocene unconformity marks the top of the glacial sequence and was formed after glacial retreat through fluvial and subaerial erosion/deposition. Overlying the glacial sequence are sediments deposited during the late Pleistocene and Holocene consisting of interbedded gravel, sand, silt, and clay. Sampling of these sediments was limited and surficial reflectors in seismic profiles were masked due to a hard bottom return. However, two depositional periods are interpreted as representing fluvial and estuarine/marine environments respectively. One sample recovered at five meters contained shell fragments within a gray fine to coarse sand possibly representing a shallow estuarine to marine environment. A coarse near surface deposit described but not recovered in all borings may represent a transgressive unconformity and resulting lag deposit however due to lack of sampling and seismic resolution in the upper 5 meters, the nature of this deposit is merely speculation. In areas where depth to the glacial surface increased, sediments ranging from sand to fine-grained silt and clay were encountered in borings. In summary, the upper 70 meters of the inner continental shelf section within the study site consists of unconsolidated sediments spanning three major depositional periods. Sediments derived from glacial activity represent the bulk of samples collected. The glacial sequences represent various depositional environments, although most samples are interpreted to be the product of glacial meltwater deposition with distribution determined by source as well as highs and lows present in the antecedent topography. Finely laminated (varved) sediment to the south of Block Island indicates the presence of proglacial lakes in the area during the time of glacial retreat. Overlying sediments represent environments ranging from fluvial to marine.

Deposition and immersion-mode nucleation of ice by three distinct samples of volcanic ash

NASA Astrophysics Data System (ADS)

Schill, G. P.; Genareau, K.; Tolbert, M. A.

2015-07-01

Ice nucleation of volcanic ash controls both ash aggregation and cloud glaciation, which affect atmospheric transport and global climate. Previously, it has been suggested that there is one characteristic ice nucleation efficiency for all volcanic ash, regardless of its composition, when accounting for surface area; however, this claim is derived from data from only two volcanic eruptions. In this work, we have studied the depositional and immersion freezing efficiency of three distinct samples of volcanic ash using Raman microscopy coupled to an environmental cell. Ash from the Fuego (basaltic ash, Guatemala), Soufrière Hills (andesitic ash, Montserrat), and Taupo (Oruanui eruption, rhyolitic ash, New Zealand) volcanoes were chosen to represent different geographical locations and silica content. All ash samples were quantitatively analyzed for both percent crystallinity and mineralogy using X-ray diffraction. In the present study, we find that all three samples of volcanic ash are excellent depositional ice nuclei, nucleating ice from 225 to 235 K at ice saturation ratios of 1.05 ± 0.01, comparable to the mineral dust proxy kaolinite. Since depositional ice nucleation will be more important at colder temperatures, fine volcanic ash may represent a global source of cold-cloud ice nuclei. For immersion freezing relevant to mixed-phase clouds, however, only the Oruanui ash exhibited appreciable heterogeneous ice nucleation activity. Similar to recent studies on mineral dust, we suggest that the mineralogy of volcanic ash may dictate its ice nucleation activity in the immersion mode.

H3.Y discriminates between HIRA and DAXX chaperone complexes and reveals unexpected insights into human DAXX-H3.3-H4 binding and deposition requirements

PubMed Central

Zink, Lisa-Maria; Delbarre, Erwan; Eberl, H. Christian; Keilhauer, Eva C.; Bönisch, Clemens; Pünzeler, Sebastian; Bartkuhn, Marek; Collas, Philippe; Mann, Matthias

2017-01-01

Abstract Histone chaperones prevent promiscuous histone interactions before chromatin assembly. They guarantee faithful deposition of canonical histones and functionally specialized histone variants into chromatin in a spatial- and temporally-restricted manner. Here, we identify the binding partners of the primate-specific and H3.3-related histone variant H3.Y using several quantitative mass spectrometry approaches, and biochemical and cell biological assays. We find the HIRA, but not the DAXX/ATRX, complex to recognize H3.Y, explaining its presence in transcriptionally active euchromatic regions. Accordingly, H3.Y nucleosomes are enriched in the transcription-promoting FACT complex and depleted of repressive post-translational histone modifications. H3.Y mutational gain-of-function screens reveal an unexpected combinatorial amino acid sequence requirement for histone H3.3 interaction with DAXX but not HIRA, and for H3.3 recruitment to PML nuclear bodies. We demonstrate the importance and necessity of specific H3.3 core and C-terminal amino acids in discriminating between distinct chaperone complexes. Further, chromatin immunoprecipitation sequencing experiments reveal that in contrast to euchromatic HIRA-dependent deposition sites, human DAXX/ATRX-dependent regions of histone H3 variant incorporation are enriched in heterochromatic H3K9me3 and simple repeat sequences. These data demonstrate that H3.Y's unique amino acids allow a functional distinction between HIRA and DAXX binding and its consequent deposition into open chromatin. PMID:28334823

Conservatism of Late Pennsylvanian vegetational patterns during short-term cyclic and long-term directional environmental change, western equatorial Pangea.

PubMed

Tabor, Neil J; Romanchock, Charles M; Looy, Cynthia V; Hotton, Carol L; Dimichele, William A; Chaney, Dan S

2013-09-19

Patterns of plant distribution by palaeoenvironment were examined across the Pennsylvanian-Permian transition in North-Central Texas. Stratigraphically recurrent packages of distinct lithofacies, representing different habitats, contain qualitatively and quantitatively different macrofloras and microfloras. The species pools demonstrate niche conservatism, remaining closely tied to specific habitats, during both short-term cyclic environmental change and a long-term trend of increasing aridity. The deposits examined principally comprise the terrestrial Markley and its approximate marine equivalent, the Harpersville Formation and parts of lower Archer City Formation. Fossiliferous deposits are lens-like, likely representing fill sequences of channels formed during abandonment phases. Palaeosols, represented by blocky mudstones, comprise a large fraction of the deposits. They suggest progressive climate change from minimally seasonal humid to seasonal subhumid to seasonal dry subhumid. Five lithofacies yielded plants: kaolinite-dominated siltstone, organic shale, mudstone beds within organic shale, coarsening upward mudstone-sandstone interbeds and channel sandstone. Both macro- and microflora were examined. Lithofacies proved compositionally distinct, with different patterns of dominance diversity. Organic shales (swamp deposits), mudstone partings (swamp drainages) and coarsening upward mudstone-sandstone interbeds (floodplains) typically contain Pennsylvanian wetland vegetation. Kaolinite-dominated siltstones and (to the extent known) sandstones contain taxa indicative of seasonally dry substrates. Some kaolinite-dominated siltstones and organic shales/coals yielded palynomorphs. Microfloras are more diverse, with greater wetland-dryland overlap than macrofloras. It appears that these two floras were coexistent at times on the regional landscape.

Conservatism of Late Pennsylvanian vegetational patterns during short-term cyclic and long-term directional environmental change, western equatorial Pangea

PubMed Central

TABOR, NEIL J.; ROMANCHOCK, CHARLES M.; LOOY, CYNTHIA V.; HOTTON, CAROL L.; DIMICHELE, WILLIAM A.; CHANEY, DAN S.

2014-01-01

Patterns of plant distribution by palaeoenvironment were examined across the Pennsylvanian–Permian transition in North–Central Texas. Stratigraphically recurrent packages of distinct lithofacies, representing different habitats, contain qualitatively and quantitatively different macrofloras and microfloras. The species pools demonstrate niche conservatism, remaining closely tied to specific habitats, during both short-term cyclic environmental change and a long-term trend of increasing aridity. The deposits examined principally comprise the terrestrial Markley and its approximate marine equivalent, the Harpersville Formation and parts of lower Archer City Formation. Fossiliferous deposits are lens-like, likely representing fill sequences of channels formed during abandonment phases. Palaeosols, represented by blocky mudstones, comprise a large fraction of the deposits. They suggest progressive climate change from minimally seasonal humid to seasonal subhumid to seasonal dry subhumid. Five lithofacies yielded plants: kaolinite-dominated siltstone, organic shale, mudstone beds within organic shale, coarsening upward mudstone–sandstone interbeds and channel sandstone. Both macro- and microflora were examined. Lithofacies proved compositionally distinct, with different patterns of dominance diversity. Organic shales (swamp deposits), mudstone partings (swamp drainages) and coarsening upward mudstone–sandstone interbeds (floodplains) typically contain Pennsylvanian wetland vegetation. Kaolinite-dominated siltstones and (to the extent known) sandstones contain taxa indicative of seasonally dry substrates. Some kaolinite-dominated siltstones and organic shales/coals yielded palynomorphs. Microfloras are more diverse, with greater wetland–dryland overlap than macrofloras. It appears that these two floras were coexistent at times on the regional landscape. PMID:25339793

Robust and Elastic Lunar and Martian Structures from 3D-Printed Regolith Inks

NASA Astrophysics Data System (ADS)

Jakus, Adam E.; Koube, Katie D.; Geisendorfer, Nicholas R.; Shah, Ramille N.

2017-03-01

Here, we present a comprehensive approach for creating robust, elastic, designer Lunar and Martian regolith simulant (LRS and MRS, respectively) architectures using ambient condition, extrusion-based 3D-printing of regolith simulant inks. The LRS and MRS powders are characterized by distinct, highly inhomogeneous morphologies and sizes, where LRS powder particles are highly irregular and jagged and MRS powder particles are rough, but primarily rounded. The inks are synthesized via simple mixing of evaporant, surfactant, and plasticizer solvents, polylactic-co-glycolic acid (30% by solids volume), and regolith simulant powders (70% by solids volume). Both LRS and MRS inks exhibit similar rheological and 3D-printing characteristics, and can be 3D-printed at linear deposition rates of 1-150 mm/s using 300 μm to 1.4 cm-diameter nozzles. The resulting LRS and MRS 3D-printed materials exhibit similar, but distinct internal and external microstructures and material porosity (~20-40%). These microstructures contribute to the rubber-like quasi-static and cyclic mechanical properties of both materials, with young’s moduli ranging from 1.8 to 13.2 MPa and extension to failure exceeding 250% over a range of strain rates (10-1-102 min-1). Finally, we discuss the potential for LRS and MRS ink components to be reclaimed and recycled, as well as be synthesized in resource-limited, extraterrestrial environments.

Evidence of ancient alteration and subaqueous activity in Oxia Planum, the candidate landing site for Exomars 2020

NASA Astrophysics Data System (ADS)

Quantin-Nataf, Cathy; Carter, John; Thollot, Patrick; Loizeau, Damien; Davis, Joel; Grindrod, Peter; lozach, Loic

2017-04-01

The ExoMars 2018 mission (ESA) has for scientific objectives to search for signs of past and present life on Mars, to investigate the water/geochemical environment as a function of depth in the shallow subsurface, to study to Martian atmospheric trace gases and to characterize the surface environment. The landing site has to be relevant with regard to these objectives while fitting the restrictive engineering constrains. From the scientific point of view, the site must be ancient, from the Early Mars period, for which many scientific evidences favor the existence of a water-related cycle. In this paper, we present the unique location called Oxia Planum, a wide clay bearing plain located between 16° and 19° North and -23° to -28° East proposed as landing site for Exomars 2020 mission. Oxia Planum is located between Ares Vallis and Marwth Vallis in a wide basin just at the outlet of Cogoon Vallis System, with elevations ranging from -2800 m down to -3100 m. The regional compositional mapping of Oxia planum has been achieved based on OMEGA data at 2.5 km/pix well as CRISM multispectral data at 200 m/pix. Mg/Fe phyllosilicates, identified and mapped based on their diagnostic absorptions at 1.4, 1.9 and 2.3 µm are exposed over about 80% of the ellipse surface. The entire unit with phyllosilicates signatures corresponds to a light-toned layered unit that is observed over a large range of elevations (from -2600 m to -3100m) suggesting that like in Marwth Vallis region, the layered and altered formation overlaps a pre-existing topography . The age returned from crater count on the clay rich formation is 3.9 Ga. At the top or embedded within the layered formation, several fluvial morphologies such as former valleys or inverted channels are observed. Also, at the top of the layered clay-rich formation, a deltaic deposit is observed suggesting sub-aqueous episodes postdating the altered layered formation. In terms of mineralogy, the putative delta fan shows layers enriched in hydrated silica. This delta fan implies a second and distinct period of alteration in Oxia Planum signed by a distinct mineralogy. In term of age, the delta has a too small surface to allow a confident age assignment from crater count. We can only state that the delta-fan is older than 3.5 Ga. Oxia Planum recorded at least two clearly distinct alteration environments and contexts: 1) the alteration of the Noachian layers and 2) the fluvio-deltaic system post-dating the Noachian clay rich unit. Deciphering the formation environments for such diverse altered rocks would fulfill the goals of the ExoMars Rover.

12 CFR 362.8 - Restrictions on activities of insured state nonmember banks affiliated with certain securities...

Code of Federal Regulations, 2014 CFR

2014-01-01

..., distribution or underwriting of stocks, bonds, debentures, notes, or other securities activity, of a type not... conducts retail sales activity with the public is physically distinct from the routine deposit taking area...

12 CFR 362.8 - Restrictions on activities of insured state nonmember banks affiliated with certain securities...

Code of Federal Regulations, 2012 CFR

2012-01-01

..., distribution or underwriting of stocks, bonds, debentures, notes, or other securities activity, of a type not... conducts retail sales activity with the public is physically distinct from the routine deposit taking area...

Microplastics and Nanoplastics in Aquatic Environments: Aggregation, Deposition, and Enhanced Contaminant Transport.

PubMed

Alimi, Olubukola S; Farner Budarz, Jeffrey; Hernandez, Laura M; Tufenkji, Nathalie

2018-02-20

Plastic litter is widely acknowledged as a global environmental threat, and poor management and disposal lead to increasing levels in the environment. Of recent concern is the degradation of plastics from macro- to micro- and even to nanosized particles smaller than 100 nm in size. At the nanoscale, plastics are difficult to detect and can be transported in air, soil, and water compartments. While the impact of plastic debris on marine and fresh waters and organisms has been studied, the loads, transformations, transport, and fate of plastics in terrestrial and subsurface environments are largely overlooked. In this Critical Review, we first present estimated loads of plastics in different environmental compartments. We also provide a critical review of the current knowledge vis-à-vis nanoplastic (NP) and microplastic (MP) aggregation, deposition, and contaminant cotransport in the environment. Important factors that affect aggregation and deposition in natural subsurface environments are identified and critically analyzed. Factors affecting contaminant sorption onto plastic debris are discussed, and we show how polyethylene generally exhibits a greater sorption capacity than other plastic types. Finally, we highlight key knowledge gaps that need to be addressed to improve our ability to predict the risks associated with these ubiquitous contaminants in the environment by understanding their mobility, aggregation behavior and their potential to enhance the transport of other pollutants.

Depositional environment of the Onverwacht sedimentary rocks Barberton greenstone belt, South Africa

NASA Astrophysics Data System (ADS)

Paris, I. A.

The Onverwacht Group is the basal part of the ca 3.5 Ga succession forming the Barberton greenstone belt. It comprises a volcanic pile overlain by a thin layer of volcaniclastic sediments which, due to silicification, are extremely well preserved. There has been a controversy as to how and in what environment these sediments were formed, different sets of data being presented to reach opposite conclusions. The Onverwacht Group has been extensively repeated tectonically and here for the first time, sediments from different structural levels are studied together. Three separate facies have been recognised, a distal and proximal turbidite facies and a subaerial facies. Deposition of Onverwacht Group sedimentary rocks occurred in an oceanic basin characterised by the presence of emergent volcanic islands. After eruption, material was deposited both subaerially and in a shallow submarine environment on the volcanic slopes and, as a result of pyroclastic flow, in the deeper parts of the basin.

Sediment facies, depositional environments, and distribution of phytoclasts in the recent Mahakam River delta, Kalimantan, Indonesia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gastaldo, R.A.; Huc, A.Y.

1992-12-01

The Mahakam River delta is a tide- and wave-dominated delta located on the edge of the Kutei basin, eastern Kalimantan, Borneo. It is a coastal deltaic sequence, Neogene to Holocene in age, from which all recoverable hydrocarbons (crude oil and natural gas) are considered to be derived from kerogen III predecessors. However, a complete understanding of the types of sediments sourcing the hydrocarbons has not yet been achieved. A vibracoring program sampled the principal fine-grained depositional environments in two transects; one within the fluvially-dominated regime, one within the tidally-dominated regime. Ten sedimentary facies are distinguished and phytoclasts have been recoveredmore » from all environments of deposition. Canopy parts from the mixed tropical forest community are preserved throughout the delta, whereas dicotyledonous angiosperm mangroves are restricted to the subtidal zone and delta front. Nypa parts are preserved in most depositional environments. In sites where there appears to be an absence of macrodetritus, dispersed cuticle is recoverable. Identifiable plant parts include wood and fibrous tissues, Nypa petioles and leaf laminae, dicotyledonous angiosperm leaves and isolated cuticles, fruits and seeds, roots and rootlets, and moss. Dammar is found either as dispersed resin ducts or amorphous clasts. Additional biotic components found in bedded plant litters include insects, gastropods, bivalves, sand dollars, ostracods, and crabs. Fluvial channels and depositional sites associated with these systems in the delta front can be differentiated from Nypa swamps and mixed tropical hardwood-palm swamps based on their phytological components and accessory biotic elements. 39 refs., 10 figs., 3 tabs.« less

Deposition rates of fungal spores in indoor environments, factors effecting them and comparison with non-biological aerosols

NASA Astrophysics Data System (ADS)

Kanaani, Hussein; Hargreaves, Megan; Ristovski, Zoran; Morawska, Lidia

Particle deposition indoors is one of the most important factors that determine the effect of particle exposure on human health. While many studies have investigated the particle deposition of non-biological aerosols, few have investigated biological aerosols and even fewer have studied fungal spore deposition indoors. The purpose of this study was, for the first time, to investigate the deposition rates of fungal particles in a chamber of 20.4 m 3 simulating indoor environments by: (1) releasing fungal particles into the chamber, in sufficient concentrations so the particle deposition rates can be statistically analysed; (2) comparing the obtained deposition rates with non-bioaerosol particles of similar sizes, investigated under the same conditions; and (3) investigating the effects of ventilation on the particle deposition rates. The study was conducted for a wide size range of particle sizes (0.54-6.24 μm), at three different air exchange rates (0.009, 1.75 and 2.5 h -1). An Ultraviolet Aerodynamic Particle Sizer Spectrometer (UVAPS) was used to monitor the particle concentration decay rate. The study showed that the deposition rates of fungal spores ( Aspergillus niger and Penicillium species) and the other aerosols (canola oil and talcum powder) were similar, especially at very low air exchange rates (in the order of 0.009). Both the aerosol and the bioaerosol deposition rates were found to be a function of particle size. The results also showed increasing deposition rates with increasing ventilation rates, for all particles under investigation. These conclusions are important in understanding the dynamics of fungal spores in the air.

SHRIMP-SI Multiple Sulfur Isotope Analysis of Sulfides from Brazilian Deposits: Analytical Capability to Resolve Single Grain Textural Complexities and Distinct Sulfur Sources

NASA Astrophysics Data System (ADS)

Ireland, T. R.; Teles, G. D. S.; Chemale, F., Jr.; Avila, J.

2016-12-01

The Archean atmosphere is thought to be several times more reducing than the present day atmosphere, and the occurrence of Mass Independent Fractionation of Sulfur isotopes (MIF-S) in sulfides of sedimentary and volcanogenic rocks older than 2.45 Ga reinforces it. The most accepted mechanism to generate MIF-S requires photochemical reactions with volcanogenic SO2 in an anoxic atmosphere (O2 levels <10-5 PAL). The identification of MIF-S, noted as Δ33S and Δ36S, requires precise measurements of less abundant 33S and 36S isotopes, which were first attained by bulk isotope analyses. However, in-situ analysis has become essential, as many of ancient sulfide samples have suffered post-depositional processes, and their primary isotopic signature from the atmosphere are now overprinted by mass-dependent fractionation processes. High-precision and resolution in situ measurements of 32S, 33S, 34S and 36S in sulfides can be achieved by SHRIMP-SI, which allows isotopic determinations with internal errors better than 0.05‰ for Δ33S and 0.2‰ for Δ36S (2SE), and reproducibility about 0.1‰ for Δ33S and better than 0.5‰ for Δ36S (2SD). Examples of the SHRIMP-SI capability are provided by multiple sulfur isotope analysis of samples from Brazil, the Au-(U) and pyrite deposits of Jacobina Basin and the massive sulfide deposits of the 3.3 Ga Mundo Novo Greenstone Belt. The level of precision and spatial resolution achievable with SHRIMP-SI allowed the isotopic distinction between sedimentary and post-depositional pyrites in Jacobina Basin, as well as the identification of different sulfur sources in the Mundo Novo Greenstone Belt VMS deposits.

Spectral and stratigraphic mapping of hydrated minerals associated with interior layered deposits near the southern wall of Melas Chasma, Mars

NASA Astrophysics Data System (ADS)

Liu, Yang; Goudge, Timothy A.; Catalano, Jeffrey G.; Wang, Alian

2018-03-01

Orbital remote sensing data acquired from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) onboard Mars Reconnaissance Orbiter (MRO), in conjunction with other datasets, are used to perform detailed spectral and stratigraphic analyses over a portion of south Melas Chasma, Mars. The Discrete Ordinate Radiative Transfer (DISORT) model is used to retrieve atmospherically corrected single scattering albedos from CRISM I/F data for mineral identification. A sequence of interbedded poly- and monohydrated sulfates associated with interior layered deposits (ILDs) is identified and mapped. Analyses from laboratory experiments and spectral unmixing of CRISM hyperspectral data support the hypothesis of precipitation and dehydration of multiple inputs of complex Mg-Ca-Fe-SO4-Cl brines. In this scenario, the early precipitated Mg sulfates could dehydrate into monohydrated sulfate due to catalytic effects, and the later-precipitated Mg sulfates from the late-stage "clean" brine could terminate their dehydration at mid-degree of hydration to form a polyhydrated sulfate layer due to depletion of the catalytic species (e.g., Ca, Fe, and Cl). Distinct jarosite-bearing units are identified stratigraphically above the hydrated sulfate deposits. These are hypothesized to have formed either by oxidation of a fluid containing Fe(II) and SO4, or by leaching of soluble phases from precursor intermixed jarosite-Mg sulfate units that may have formed during the later stages of deposition of the hydrated sulfate sequence. Results from stratigraphic analysis of the ILDs show that the layers have a consistent northward dip towards the interior of the Melas Chasma basin, a mean dip angle of ∼6°, and neighboring strata that are approximately parallel. These strata are interpreted as initially sub-horizontal layers of a subaqueous, sedimentary evaporite deposits that underwent post-depositional tilting from slumping into the Melas Chasma basin. The interbedded hydrated sulfate units and jarosite-bearing units, which have distinct stratigraphic relationships, are indicative of a complex sedimentary and aqueous history in south Melas Chasma.

Recent progress concerning the production of controlled highly oriented electrospun nanofibrous arrays

NASA Astrophysics Data System (ADS)

Manea, L. R.; Hristian, L.; Leon, A. L.; Popa, A.

2016-08-01

Among the foreground domains of all the research-development programs at national and international level, a special place is occupied by that concerning the nanosciences, nanotechnologies, new materials and technologies. Electrospinning found a well-deserved place in this space, offering the preparation of nanomaterials with distinctive properties and applications in medicine, environment, photonic sensors, filters, etc. These multiple applications are generated by the fact that the electrospinning technology makes available the production of nanofibers with controllable characteristics (length, porosity, density, and mechanical characteristics), complexity and architecture. The apparition of 3D printing technology favors the production of complex nanofibrous structures, controlled assembly, self-assembly of electrospun nanofibers for the production of scaffolds used in various medical applications. The architecture of fibrous deposits has a special influence on the subsequent development of the cells of the reconstructed organism. The present work proposes to study of recent progress concerning the production of controlled highly oriented electrospun nanofibrous arrays and progress in research on the production of complex 2D and 3D structures.

Gravity flows associated with flood events and carbon burial: Taiwan as instructional source area.

PubMed

Liu, James T; Kao, Shuh-Ji; Huh, Chih-An; Hung, Chin-Chang

2013-01-01

Taiwan's unique setting allows it to release disproportionately large quantities of fluvial sediment into diverse dispersal systems around the island. Earthquakes, lithology, topography, cyclone-induced rainfall, and human disturbance play major roles in the catchment dynamics. Deep landslides dominate the sediment-removal process on land, giving fluvial sediment distinct geochemical signals. Extreme conditions in river runoff, sediment load, nearshore waves and currents, and the formation of gravity flows during typhoon events can be observed within short distances. Segregation of fresh biomass and clastic sediment occurs during the marine transport process, yet turbidity currents in the Gaoping Submarine Canyon carry woody debris. Strong currents in the slope and back-arc basin of the Okinawa Trough disperse fine-grained sediments rapidly and widely. Temporal deposition and remobilization may occur when the shallow Taiwan Strait acts as a receptacle. Taiwan can therefore serve as a demonstration of the episodic aspect of the source-to-sink pathway to both the coastal and deep-ocean environments.

Interfacial Mechanism in Lithium-Sulfur Batteries: How Salts Mediate the Structure Evolution and Dynamics.

PubMed

Lang, Shuang-Yan; Xiao, Rui-Juan; Gu, Lin; Guo, Yu-Guo; Wen, Rui; Wan, Li-Jun

2018-06-08

Lithium-sulfur batteries possess favorable potential for energy-storage applications due to their high specific capacity and the low cost of sulfur. Intensive understanding of the interfacial mechanism, especially the polysulfide formation and transformation under complex electrochemical environment, is crucial for the build-up of advanced batteries. Here we report the direct visualization of interfacial evolution and dynamic transformation of the sulfides mediated by the lithium salts via real-time atomic force microscopy monitoring inside a working battery. The observations indicate that the lithium salts influence the structures and processes of sulfide deposition/decomposition during discharge/charge. Moreover, the distinct ion interaction and diffusion in electrolytes manipulate the interfacial reactions determining the kinetics of the sulfide transformation. Our findings provide deep insights into surface dynamics of lithium-sulfur reactions revealing the salt-mediated mechanisms at nanoscale, which contribute to the profound understanding of the interfacial processes for the optimized design of lithium-sulfur batteries.

Change in the fouling propensity of sludge in membrane bioreactors (MBR) in relation to the accumulation of biopolymer clusters.

PubMed

Sun, Fei-yun; Wang, Xiao-mao; Li, Xiao-yan

2011-04-01

A membrane bioreactor (MBR) and an activated sludge process (ASP) were operated side by side to evaluate the change of sludge supernatant characteristics and the evolution of the sludge fouling propensity. The MBR sludge had a higher organic concentration and more biopolymer clusters (BPC) in the supernatant compared with ASP. BPC increased in both concentration and size in the MBR. The results show that the change in the liquid-phase property had a profound effect on the sludge fouling propensity. MBR operation transformed typical activated sludge to MBR sludge with a higher fouling propensity. Distinct from the ASP, membrane filtration retained soluble microbial products (SMP) within the MBR, and the vast membrane surface provided a unique environment for the transformation of SMP to large size BPC, leading to further sludge deposition on the membrane surface. Thus, membrane filtration is the crucial cause of the inevitable fouling problem in submerged MBRs. Copyright © 2011 Elsevier Ltd. All rights reserved.

Improved Regolith-Landform and Geological Mapping using AIRSAR Data as an Aid to Mineral Exploration in the North-Eastern Goldfields Region, Western Australia

NASA Technical Reports Server (NTRS)

Tapley, Ian J.

1996-01-01

The distinctive contribution of AIRSAR data in characterizing the regolith-landforms in a relatively vegetation free environment are discussed. AIRSAR frame processed data were initially MAF-cleaned to enhance the signal content of the data before geocoding to AMG coordinates. Colors in a three frequency single polarization combination image C-, L- P- bands, and in an enhancement of pedestal height, relate directly to the scale of surface roughness of the various regolith units Examination of the AIRSAR enhancements reveals that in mafic terrain, and to a lesser extent, in felsic terrain, AIRSAR data provides discrimination between the principle geomorphic regimes, relict, erosional and depositional. A multivariate statistical technique called an all-possible subsets calculation was used to examine the degree of polarimetric separation between selected regolith-landforms for all combinations of the nine band AIRSAR radar. An unanticipated aspect of the research was the identification on the AIRSAR imagery of previously unmapped structural features.

Dissolved oxygen sensing using organometallic dyes deposited within a microfluidic environment

NASA Astrophysics Data System (ADS)

Chen, Q. L.; Ho, H. P.; Jin, L.; Chu, B. W.-K.; Li, M. J.; Yam, V. W.-W.

2008-02-01

This work primarily aims to integrate dissolved oxygen sensing capability with a microfluidic platform containing arrays of micro bio-reactors or bio-activity indicators. The measurement of oxygen concentration is of significance for a variety of bio-related applications such as cell culture and gene expression. Optical oxygen sensors based on luminescence quenching are gaining much interest in light of their low power consumption, quick response and high analyte sensitivity in comparison to similar oxygen sensing devices. In our microfluidic oxygen sensor device, a thin layer of oxygen-sensitive luminescent organometallic dye is covalently bonded to a glass slide. Micro flow channels are formed on the glass slide using patterned PDMS (Polydimethylsiloxane). Dissolved oxygen sensing is then performed by directing an optical excitation probe beam to the area of interest within the microfluidic channel. The covalent bonding approach for sensor layer formation offers many distinct advantages over the physical entrapment method including minimizing dye leaching, ensuring good stability and fabrication simplicity. Experimental results confirm the feasibility of the device.

Physical criteria for distinguishing sandy tsunami and storm deposits using modern examples

USGS Publications Warehouse

Morton, Robert A.; Gelfenbaum, Guy; Jaffe, Bruce E.

2007-01-01

Modern subaerial sand beds deposited by major tsunamis and hurricanes were compared at trench, transect, and sub-regional spatial scales to evaluate which attributes are most useful for distinguishing the two types of deposits. Physical criteria that may be diagnostic include: sediment composition, textures and grading, types and organization of stratification, thickness, geometry, and landscape conformity. Published reports of Pacific Ocean tsunami impacts and our field observations suggest that sandy tsunami deposits are generally 30 cm thick, generally extend The distinctions between tsunami and storm deposits are related to differences in the hydrodynamics and sediment-sorting processes during transport. Tsunami deposition results from a few high-velocity, long-period waves that entrain sediment from the shoreface, beach, and landward erosion zone. Tsunamis can have flow depths greater than 10 m, transport sediment primarily in suspension, and distribute the load over a broad region where sediment falls out of suspension when flow decelerates. In contrast, storm inundation generally is gradual and prolonged, consisting of many waves that erode beaches and dunes with no significant overland return flow until after the main flooding. Storm flow depths are commonly

Syn-deformational features of Carlin-type Au deposits

USGS Publications Warehouse

Peters, S.G.

2004-01-01

Syn-deformational ore deposition played an important role in some Carlin-type Au deposits according to field and laboratory evidence, which indicates that flow of Au-bearing fluids was synchronous with regional-scale deformation events. Gold-related deformation events linked to ore genesis were distinct from high-level, brittle deformation that is typical of many epithermal deposits. Carlin-type Au deposits, with brittle-ductile features, most likely formed during tectonic events that were accompanied by significant fluid flow. Interactive deformation-fluid processes involved brittle-ductile folding, faulting, shearing, and gouge development that were focused along illite-clay and dissolution zones caused by hydrothermal alteration. Alteration along these deformation zones resulted in increased porosity and enhancement of fluid flow, which resulted in decarbonated, significant dissolution, collapse, and volume and mass reduction. Carlin-type Au deposits commonly are hosted in Paleozoic and Mesozoic sedimentary rocks (limestone, siltstone, argillite, shale, and quartzite) on the margins of cratons. The sedimentary basins containing the host rocks underwent tectonic events that influenced the development of stratabound, structurally controlled orebodies. Published by Elsevier Ltd.

Interior trough deposits on Mars: Subice volcanoes?

USGS Publications Warehouse

Chapman, M.G.; Tanaka, K.L.

2001-01-01

Widespread, several-kilometer-thick successions of layered deposits occur as mounds that partly fill the troughs or chasmata that compose the Valles Marineris on Mars. Like terrestrial subice volcanoes, the layered deposits occur in a volcano-tectonic setting within basins that may have held ponded water or ice. On the basis of their dimensions, morphologies, and associated catastrophic floods and other geologic events as shown in Viking and new Mars Global Surveyor (MGS) data sets, we suggest that the interior deposits are volcanic in origin and possibly generated by subice eruptions. A tuya origin for the mounds can explain the lack of external sediment, mound heights that can rival the plateau, local flat-topped mesas, morphologically distinct mounds of different ages, horizontal to steep dips, fine-grained materials, indications of rare volcanic vents and lava flows, and spectral composition. The extremely diverse layering of west Candor Chasma and possible volcanic cones in Melas may have formed by related subaerial eruptions. Consistent with the suggestion that interior deposits are eroding out of the wall rock, some deposits could have been erupted from sites along the walls.

[Observation of ozone dry deposition in the field of winter wheat.

PubMed

Li, Shuo; Zheng, You Fei; Wu, Rong Jun; Yin, Ji Fu; Xu, Jing Xin; Zhao, Hui; Sun, Jian

2016-06-01

Ozone is one of the main atmospheric pollutants over surface layer, and its increasing surface ozone concentration and its impact on main crops have become the focus of the public. In order to explore ozone deposition law and environmental factors influencing ozone deposition process, this study used the micrometeorological methods and carried out the experiment under natural conditions. The results showed that during the observational period (the vigorously growing season of wheat), the mean value of ozone flux was -0.35 μg·m -2 ·s -1 (the negative sign indicated that the deposition direction was toward the ground). The mean rate of ozone deposition was 0.55 cm·s -1 . The mean value of aerodynamic resistance was 30 s·m -1 , the mean value of sub-layer resistance was 257 s·m -1 , and that of the canopy layer stomatic resistance was 163 s·m -1 . All the test parameters presented distinct diurnal fluctuation. The ozone deposition resistance was influenced by friction velocity, solar radiation velocity, temperature, relative humidity and other factors.

Microfossils in cherts from the Middle Riphean (Mesoproterozoic) Avzyan Formation, southern Ural Mountains, Russian Federation

NASA Technical Reports Server (NTRS)

Sergeev, V. N.; Knoll, A. H. (Principal Investigator)

1994-01-01

A diverse assemblage of well-preserved microorganisms has been detected in black cherts from the approximately 1200 Ma-old Avzyan Formation (Suite) of the southern Ural Mountains, Russian Federation. The lower Kataskin Member contains a diverse, abundant microbiota dominated by mat-forming filamentous cyanobacteria, several types of colonial unicells, and morphologically distinctive stalked cyanobacteria. The upper Revet Member contains a less diverse biota dominated by unicellular cyanobacteria. Palaeoecological evidence indicates that the microbial community of the Kataskin Member inhabited a shallow water, presumably marine, carbonate environment. Revet microorganisms possibly lived in restricted peritidal environments. The biostratigraphic significance of the Avzyan microbiota is limited. Many of the taxa are long-ranging; they were already abundant in Palaeoproterozoic successions and continue into the Neoproterozoic. Nevertheless, in many respects, the Kataskin assemblage is comparable to those reported from the Middle-Late Riphean deposits of Northern America, Australia and Eurasia. The following taxa are here described: Chroococcaceae-Eogloeocapsa avzyanica Sergeev, Gloeodiniopsis lamellosa Schopf emend. Knoll et Golubic; Entophysalidaceae-Eoentophysalis belcherensis Hofmann; Dermocarpaceae-Polybessurus bipartitus Fairchild ex Green et al.; Nostocaceae-Eosphaeronostoc kataskinicum Sergeev; Nostocaceae or Oscillatoriaceae-Siphonophycus robustum (Schopf) emend. Knoll et Golubic emend. Knoll et al., Siphonophycus sp.; Incertae sedis-Eosynechococcus amadeus Knoll et Golubic.

The deep permafrost carbon pool of the Yedoma region in Siberia and Alaska

PubMed Central

Strauss, Jens; Schirrmeister, Lutz; Grosse, Guido; Wetterich, Sebastian; Ulrich, Mathias; Herzschuh, Ulrike; Hubberten, Hans-Wolfgang

2013-01-01

[1] Estimates for circumpolar permafrost organic carbon (OC) storage suggest that this pool contains twice the amount of current atmospheric carbon. The Yedoma region sequestered substantial quantities of OC and is unique because its deep OC, which was incorporated into permafrost during ice age conditions. Rapid inclusion of labile organic matter into permafrost halted decomposition and resulted in a deep long-term sink. We show that the deep frozen OC in the Yedoma region consists of two distinct major subreservoirs: Yedoma deposits (late Pleistocene ice- and organic-rich silty sediments) and deposits formed in thaw-lake basins (generalized as thermokarst deposits). We quantified the OC pool based on field data and extrapolation using geospatial data sets to 83 + 61/−57 Gt for Yedoma deposits and to 128 + 99/−96 Gt for thermokarst deposits. The total Yedoma region 211 + 160/−153 Gt is a substantial amount of thaw-vulnerable OC that must be accounted for in global models. PMID:26074633

Crossed optical and chemical evaluations of modern glass soiling in various European urban environments

NASA Astrophysics Data System (ADS)

Favez, Olivier; Cachier, Hélène; Chabas, Anne; Ausset, Patrick; Lefevre, Roger

As part of the MULTI-ASSESS and VIDRIO EC projects, the soiling of modern glass is characterised in various European urban atmospheres. Our original methodology relies on crossed chemical measurements of the deposit (evaluation of the ion, elemental and organic carbon contents, and subsequent "mass closure") and exhaustive measurements of glass optical properties (light reflectance, transmittance and absorption). Samples were exposed sheltered from rain in Athens, Krakow, London, Montelibretti (Italy), Prague and Troyes (France), during increasing exposure durations, up to more than two years. Although a slowing down of the deposition rate is observed for some species at some sites, no obvious saturation phenomenon seems to occur for the particle deposition. The chemical composition of the deposit is shown to reflect the atmospheric environment of the exposure site. Some post-deposit evolutions, such as the disappearance of ammonium and possibly of particulate organic matter, are found to occur. For thin deposits, the glass optical properties (e.g. light absorption and diffuse transmittance) are found to evolve quasi-linearly with species concentrations (EC and ions, respectively). However, for conditions creating heavier deposits such as long time exposures in rather polluted environments, a saturation phenomenon is observed. Using a simple model, light absorption, which is primarily due to EC particles, is shown to reach the saturation level ( S) for A≈16% and the concentration for which the semi-saturation level is reached (C 1/2) is found to be about 15 μgC of EC/cm 2. For diffuse transmittance, due to scattering species, these parameters are found to be about 30% and 65 μg of ions/cm 2, respectively. These values may be considered as representative of the soiling in Europe.

Microbial Populations in Extreme Environments: Investigations and Characterizations of the Microbiology and Geochemistry of Galapagos Island Fumaroles

NASA Astrophysics Data System (ADS)

Mayhew, L. E.; Childers, S. E.; Geist, D.

2005-12-01

The extreme physiochemical conditions, insularity, and wide range in ages of fumaroles of the Galapagos Islands provide an excellent opportunity to explore for novel microorganisms and to study life in extreme environments. This is the first study that measures microbial diversity of Galapagos fumaroles. Forty-seven samples were collected from six distinct fumarole fields on Sierra Negra and Alcedo volcanoes. Vulcan Chico, on Sierra Negra, was activated during the last eruption in 1979. Two of the other fumarole fields on Sierra Negra are associated with a long-lived fault system on the caldera floor and are therefore likely to be significantly older. The fault-associated fumaroles have widespread alteration haloes (up to 100 m in diameter) and thick deposits of native sulfur. The most vigorous of the fumarole fields on Alcedo activated in late 1993 to early 1994. The second fumarole field on Alcedo is associated with a recently extinct geyser and the third is located on a rhyolite vent. A diversity of colors was observed in the substrates at all of the fumarole fields and some may be the result of microbial activity. Collection sites were chosen on the basis of temperature and the variations in the substrate in order to obtain samples from a variety of environments. Temperatures at sample sites range from 25.0 to 178.5° C, and pH from 0 to 6. The material collected varies between sites and includes crystalline sulfur deposits, clay, sandy and rocky soils, and microbial mats. Substrate material is characterized by powder x-ray diffractometry and scanning electron microscopy and gases collected from five of the fumarole fields are being analyzed to test for chemical controls on the microbial populations. Genomic DNA is being extracted from all of the samples. Primers for Bacteria and Archaea are used for PCR amplification of the 16S rRNA gene. To date, 22 of 37 processed samples have amplifiable DNA. Microbial diversity of samples possessing amplifiable DNA is being assessed by denaturing gradient gel electrophoresis (DGGE). These results may reveal the presence of novel organisms and will provide insights into how vent age, insularity, temperature, pH, and geochemistry influence the microbial populations in extreme environments in the Galapagos Islands.

Glacial Extent During the Late Early Miocene (18-16 Ma): Results from the ANDRILL AND-2A Drillcore, Southern McMurdo Sound Project, Antarctica

NASA Astrophysics Data System (ADS)

Pekar, Stephen; Koss, Howard; Passchier, Sandra

2010-05-01

Litho- and sequence stratigraphic results from the ANtarctic Geological DRILLing Program (ANDRILL) Southern McMurdo Sound (SMS) AND-2A drill hole indicate that glacial conditions varied widely in the western Ross Sea between the two isotopic Mi events (i.e., inferred glacioeustasy) Mi1b (17.7 Ma) and Mi2 (16.2 Ma). Most of this interval had not been previously recovered from the Antarctic continental margin providing the first opportunity to use direct evidence in understanding the evolution of the ice sheet during this time. During the 2007 austral spring/summer, the SMS drill hole cored 1138 meters of sediments, with ~98% recovery. The section between 700 and 400 mbsf has high sedimentation rates (180 m/ my) and excellent age control, based on radiometric ages and magnetostratigraphy, providing an exceptional record of glacial advances and retreats deposited in a shallow water environment in Antarctica between 18 and 16 Ma. Approximately twenty sequences within this interval were identified. Each sequence is bounded by distinct surfaces characterized by a pronounced shift in lithofacies, with typically more ice distal facies below (e.g., characteristic of open marine to iceberg influenced depositional environments), and more proximal facies above (e.g., sandy massive diamictites and conglomerates). Lithofacies and grain size analysis suggest that these cycles are controlled by a combination of water depth and ice proximity. A surface at 648.74 mbsf contains a hiatus that spans 18.0-17.6 Ma and correlates to the isotopic event Mi1b. This surface separates a prolonged interval of glacial advance over this site below, based on extensive sediment deformation and more ice distal environments above. A sharp surface at 436.13 mbsf (~16.3 Ma), interpreted to represent glacial maximum extent, contains a possible short hiatus and is correlated to the Mi2 event. In contrast, although the lithofacies indicates a glacial advance, evidence of ice grounding at 436 mbsf is equivocal, suggesting a smaller advance than for the one at the Mi1b event. Between these two ice advances, the lithofacies indicates generally more distal ice environments and therefore less ice volume and correlates to the early Miocene Climatic Optimum (17.2-16.4 Ma).

Fate and agricultural consequences of leachable elements added to the environment from the 2011 Cordón Caulle tephra fall

NASA Astrophysics Data System (ADS)

Stewart, Carol; Craig, Heather M.; Gaw, Sally; Wilson, Thomas; Villarosa, Gustavo; Outes, Valeria; Cronin, Shane; Oze, Christopher

2016-11-01

The June 2011 eruption of Cordón Caulle volcano, Chile, dispersed tephra over 350,000 km2, including productive agricultural land. This resulted in the death of nearly one million livestock. Two distinct environments were affected: a proximal temperate Andean setting, and the semi-arid Argentine steppe farther from the volcano. The purpose of this study was to better understand the fate and agricultural consequences of leachable elements added to the environment by this large silicic tephra fall. Tephra, soil and surface water samples across the depositional area were collected both immediately after the eruption (tephra and water) and nine months afterwards (tephra, soil and water). Tephra samples were analysed following a new hazard assessment protocol developed by the International Volcanic Health Hazard Network (IVHHN). Water-extractable element concentrations in freshly-collected tephra were very low to low compared to other eruptions, and showed no trends with distance from the volcano. Surface water analyses suggested short-term changes to water composition due to the release of elements from tephra. No effect on the fertility of soils underlying tephra was apparent after nine months. Water-extractable fluorine (F) in freshly-collected tephra ranged from 12 to 167 mg/kg, with a median value of 67 mg/kg. Based on parallels with the 11-12 October 1995 eruption of Ruapehu volcano, New Zealand, we conclude that F toxicity was a possible contributing factor to the large-scale livestock deaths as well as to chronic fluorosis widely reported in wild deer populations across the Cordón Caulle tephra depositional area. Finally, we recommend that effective response to widespread tephra fall over agricultural areas should include: (1) rapid, statistically representative field sampling of tephra, soils, surface water supplies and forage crops; (2) analysis using appropriate and reliable laboratory methods; (3) modelling both short and long-term impacts on the ecosystem, especially for elements that may generate chronic hazard; (4) timely dissemination of results to agricultural agencies; (5) longitudinal sampling and monitoring to adapt impact models; and (6) developing reliable animal fatality diagnoses through autopsies and chemical analysis.

Environmental changes in the central Po Plain (northern Italy) due to fluvial modifications and anthropogenic activities

NASA Astrophysics Data System (ADS)

Marchetti, Mauro

2002-05-01

The fluvial environment of the central Po Plain, the largest plain in Italy, is discussed in this paper. Bounded by the mountain chains of the Alps and the Apennines, this plain is a link between the Mediterranean environment and the cultural and continental influences of both western and eastern Europe. In the past decades, economic development has been responsible for many changes in the fluvial environment of the area. This paper discusses the changes in fluvial dynamics that started from Late Pleistocene and Early Holocene due to distinct climatic changes. The discussion is based on geomorphological, pedological, and archaeological evidences and radiocarbon dating. In the northern foothills, Late Pleistocene palaeochannels indicate several cases of underfit streams among the northern tributaries of the River Po. On the other hand, on the southern side of the Po Plain, no geomorphological evidence of similar discharge reduction has been found. Here, stratigraphic sections, together with archaeological remains buried under the fluvial deposits, show a reduction in the size of fluvial sediments after the 10th millennium BC. During the Holocene, fluvial sedimentation became finer, and was characterised by minor fluctuations in the rate of deposition, probably related to short and less intense climatic fluctuations. Given the high rate of population growth and the development of human activities since the Neolithic Age, human influence on fluvial dynamics, especially since the Roman Age, prevailed over other factors (i.e., climate, tectonics, vegetation, etc.). During the Holocene, the most important changes in the Po Plain were not modifications in water discharge but in sediment. From the 1st to 3rd Century AD, land grants to war veterans caused almost complete deforestation, generalised soil erosion, and maximum progradation of the River Po delta. At present, land abandonment in the mountainous region has led to reafforestation. Artificial channel control in the mountain sector of the basins and in-channel gravel extraction (now illegal but very intense in the 1960s and 1970s) are causing erosion along the rivers and along large sectors of the Adriatic coast. These changes are comparable with those occurring in basins of other Mediterranean rivers.

Descriptive models, grade-tonnage relations, and databases for the assessment of sediment-hosted copper deposits: with emphasis on deposits in the Central Africa Copperbelt, Democratic Republic of the Congo and Zambia: Chapter J in Global mineral resource assessment

USGS Publications Warehouse

Taylor, Cliff D.; Causey, J. Douglas; Denning, Paul; Hammarstrom, Jane M.; Hayes, Timothy S.; Horton, John D.; Kirschbaum, Michael J.; Parks, Heather L.; Wilson, Anna B.; Wintzer, Niki E.; Zientek, Michael L.

2013-01-01

Chapter 1 of this report summarizes a descriptive model of sediment-hosted stratabound copper deposits. General characteristics and subtypes of sediment-hosted stratabound copper deposits are described based upon worldwide examples. Chapter 2 provides a global database of 170 sediment-hosted copper deposits, along with a statistical evaluation of grade and tonnage data for stratabound deposits, a comparison of stratabound deposits in the CACB with those found elsewhere, a discussion of the distinctive characteristics of the subtypes of sediment-hosted copper deposits that occur within the CACB, and guidelines for using grade and tonnage distributions for assessment of undiscovered resources in sediment-hosted stratabound deposits in the CACB. Chapter 3 presents a new descriptive model of sediment-hosted structurally controlled replacement and vein (SCRV) copper deposits with descriptions of individual deposits of this type in the CACB and elsewhere. Appendix A describes a relational database of tonnage, grade, and other information for more than 100 sediment-hosted copper deposits in the CACB. These data are used to calculate the pre-mining mineral endowment for individual deposits in the CACB and serve as the basis for the grade and tonnage models presented in chapter 2. Appendix B describes three spatial databases (Esri shapefiles) for (1) point locations of more than 500 sediment-hosted copper deposits and prospects, (2) projected surface extent of 86 selected copper ore bodies, and (3) areal extent of 77 open pits, all within the CACB.

Spotting the differences: probing host/microbiota interactions with a dedicated software tool for the analysis of faecal outputs in Drosophila.

PubMed

Wayland, Matthew T; Defaye, Arnaud; Rocha, Joao; Jayaram, Satish Arcot; Royet, Julien; Miguel-Aliaga, Irene; Leulier, François; Cognigni, Paola

2014-10-01

The intestinal physiology of Drosophila melanogaster can be monitored in an integrative, non-invasive manner by analysing graphical features of the excreta produced by flies fed on a dye-supplemented diet. This assay has been used by various labs to explore gut function and its regulation. To facilitate its use, we present here a free, stand-alone dedicated software tool for the analysis of fly excreta. The Ultimate Reader of Dung (T.U.R.D.) is designed to offer a flexible environment for a wide range of experimental designs, with special attention to automation and high-throughput processing. This software detects the distinctive changes in acid-base and water balance previously reported to occur in response to dietary challenges and mating. We have used T.U.R.D. to test the contribution of the bacterial environment of the flies to various intestinal parameters including the established diet- and mating-triggered responses. To this end, we have analysed the faecal patterns of flies reared in germ-free conditions, upon re-association with controlled microbiota and subjected to food-borne or systemic, non-lethal bacterial infections. We find that the tested faecal outputs are unchanged in all these conditions, suggesting that the impact of the bacterial environment on the intestinal features highlighted by faecal deposit analysis is minimal. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.