Predicting nest success from habitat features in aspen forests of the central Rocky Mountains

Treesearch

Heather M. Struempf; Deborah M. Finch; Gregory Hayward; Stanley Anderson

2001-01-01

We collected nesting data on bird use of aspen stands in the Routt and Medicine Bow National Forests between 1987 and 1989. We found active nest sites of 28 species of small nongame birds on nine study plots in undisturbed aspen forests. We compared logistic regression models predicting nest success (at least one nestling) from nest-site or stand-level habitat...

Survival of various implant-supported prosthesis designs following 36 months of clinical function.

PubMed

Rodriguez, A M; Orenstein, I H; Morris, H F; Ochi, S

2000-12-01

The use of endosseous dental implants to replace natural teeth lost to trauma, dental caries, or periodontal disease has become a predictable form of prosthetic treatment since gaining popularity in the early 1980s. While numerous clinical studies have focused on the survival of implants, few address the survival of different prosthesis designs. Beginning in 1991, 882 prostheses supported by more than 2,900 implants (687 patients) were placed by the Department of Veterans Affairs Dental Implant Clinical Research Group (DICRG). These prostheses were divided into five research strata based on arch location. The recommended design for each stratum was: bar-supported overdenture (maxillary completely edentulous); screw-retained hybrid denture (mandibular completely edentulous); screw-retained fixed partial denture (mandibular and maxillary posterior partially edentulous); and cemented single crown (maxillary anterior single tooth). Alternative overdenture designs were utilized in the edentulous arches when the recommended prosthesis could not be fabricated. Prosthesis success rates for the research strata were calculated for an observation time of up to 36 months following prosthesis placement. Success rates for the maxillary edentulous stratum ranged from 94.6% for the bar-retained overdenture supported by five to six fixtures to 81.8% for the cap-retained overdenture. The mandibular edentulous strata produced success rates of 98.1% for the fixed hybrid prosthesis to 91.7% for the cap-retained prosthesis. Success rates for maxillary and mandibular posterior fixed partial dentures were 94.3% and 92.6%, respectively, while the maxillary anterior single-tooth prosthesis yielded a success rate of 98.1% for the 36-month observation period. The recommended prosthesis designs investigated in this study proved to be reliable, with encouraging success rates for an observation period of 36 months following placement.

Clinical application of a tissue-cultured skin autograft: an alternative for the treatment of non-healing or slowly healing wounds?

PubMed

Zöller, Nadja; Valesky, Eva; Butting, Manuel; Hofmann, Matthias; Kippenberger, Stefan; Bereiter-Hahn, Jürgen; Bernd, August; Kaufmann, Roland

2014-01-01

The treatment regime of non-healing or slowly healing wounds is constantly improving. One aspect is surgical defect coverage whereby mesh grafts and keratinocyte suspension are applied. Tissue-cultured skin autografts may be an alternative for the treatment of full-thickness wounds and wounds that cover large areas of the body surface. Autologous epidermal and dermal cells were isolated, expanded in vitro and seeded on collagen-elastin scaffolds. The developed autograft was immunohistochemically characterized and subsequently transplanted onto a facial chronic ulceration of a 71-year-old patient with vulnerable atrophic skin. Characterization of the skin equivalent revealed comparability to healthy human skin due to the epidermal strata, differentiation and proliferation markers. Within 138 days, the skin structure at the transplantation site closely correlated with the adjacent undisturbed skin. The present study demonstrates the comparability of the developed organotypic skin equivalent to healthy human skin and the versatility for clinical applications.

Seismic evidence of Quaternary faulting in the Benton Hills area, southeast Missouri

USGS Publications Warehouse

Palmer, J.R.; Shoemaker, M.; Hoffman, D.; Anderson, N.L.; Vaughn, J.D.; Harrison, R.W.

1997-01-01

Two reflection seismic profiles at English Hill, across the southern edge of the Benton Hills escarpment, southeast Missouri, establish that geologic structures at English Hill are of tectonic origin. The lowland area to the south of the escarpment is relatively undisturbed. The geology at English Hill is structurally complex, and reflection seismic and geologic data indicate extensive and episodic faulting of Paleozoic, Cretaceous, Tertiary, and Quaternary strata. The individual faults have near-vertical fault surfaces with maximum vertical separations on the order of 15 m. They appear to be clustered in north-northeast trending zones that essentially parallel one of the dominant Benton Hills structural trends. These observations suggest that previously mapped Quaternary faults at English Hill are deep-seated and tectonic in origin. This paper documents recent faulting at English Hill and is the first time late Quaternary, surface-rupture faulting has been recognized in the middle Mississippi River Valley region outside of the New Madrid seismic zone. This has important implications for earthquake assessment in the midcontinent.

Terrestrial Responses to Variability in the Southern Westerlies Inferred from Deep Holocene Peat Archives

NASA Astrophysics Data System (ADS)

Hughes, P. D. M.; Mauquoy, D.; van Bellen, S.; Roland, T. P.; Loader, N.; Street-Perrott, F. A.; Daley, T.

2017-12-01

The deep ombrotrophic peat bogs of Chile are located throughout the latitudes dominated by the southern westerly wind belt. The domed surfaces of these peatlands make them sensitive to variability in summer atmospheric moisture balance and the near-continuous accumulation of deep peat strata throughout the Holocene to the present day means that these sites provide undisturbed archives of palaeoclimatic change. We have reconstructed late-Holocene bog water table depths - which can be related to changes in the regional balance of precipitation to evaporation (P-E) - from a suite of peat bogs located in three areas of Tierra del Feugo, Chile, under the main path of the SWWB. Water-table depths were reconstructed from sub-fossil testate amoebae assemblages using a conventional transfer function to infer past water-table depths, based on taxonomic classification of tests but also an innovative trait-based transfer function to infer the same parameter. Water table reconstructions derived from the two methods were consistent within sites. They show that mire water tables have been relatively stable in the last 2000 years across Tierra del Feugo. Higher water table levels, most probably indicating increased effective precipitation, were found between c. 1400 and 900 cal. BP., whereas a consistent drying trend was reconstructed across the region in the most recent peat strata. This shift may represent a pronounced regional decrease in precipitation and/or a change to warmer conditions linked to strengthening of the SWWB. However, other factors such as recent thinning of the ozone layer over Tierra del Fuego could have contributed to recent shifts in some testate amoebae species.

Comparison of vesicular-arbuscular mycorrhizae in plants from disturbed and adjacent undisturbed regions of a coastal salt marsh in Clinton, Connecticut, USA

NASA Astrophysics Data System (ADS)

Cooke, John C.; Lefor, Michael W.

1990-01-01

Roots of salt marsh plant species Spartina alterniflora, S. patens, Distichlis spicata, and others were examined for the presence of vesicular-arbuscular mycorrhizal (VAM) fungi. Samples were taken from introduced planted material in a salt marsh restoration project and from native material in adjacent marsh areas along the Indian River, Clinton, Connecticut, USA. After ten years the replanted area still has sites devoid of vegetation. The salt marsh plants introduced there were devoid of VAM fungi, while high marsh species from the adjacent undisturbed region showed consistent infection, leading the authors to suggest that VAM fungal infection of planting stocks may be a factor in the success of marsh restoration.

Carbonate rocks of the Seward Peninsula, Alaska: Their correlation and paleogeographic significance

USGS Publications Warehouse

Dumoulin, Julie A.; Harris, Alta; Repetski, John E.

2014-01-01

Paleozoic carbonate strata deposited in shallow platform to off-platform settings occur across the Seward Peninsula and range from unmetamorphosed Ordovician–Devonian(?) rocks of the York succession in the west to highly deformed and metamorphosed Cambrian–Devonian units of the Nome Complex in the east. Faunal and lithologic correlations indicate that early Paleozoic strata in the two areas formed as part of a single carbonate platform. The York succession makes up part of the York terrane and consists of Ordovician, lesser Silurian, and limited, possibly Devonian rocks. Shallow-water facies predominate, but subordinate graptolitic shale and calcareous turbidites accumulated in deeper water, intraplatform basin environments, chiefly during the Middle Ordovician. Lower Ordovician strata are mainly lime mudstone and peloid-intraclast grainstone deposited in a deepening upward regime; noncarbonate detritus is abundant in lower parts of the section. Upper Ordovician and Silurian rocks include carbonate mudstone, skeletal wackestone, and coral-stromatoporoid biostromes that are commonly dolomitic and accumulated in warm, shallow to very shallow settings with locally restricted circulation. The rest of the York terrane is mainly Ordovician and older, variously deformed and metamorphosed carbonate and siliciclastic rocks intruded by early Cambrian (and younger?) metagabbros. Older (Neoproterozoic–Cambrian) parts of these units are chiefly turbidites and may have been basement for the carbonate platform facies of the York succession; younger, shallow- and deep-water strata likely represent previously unrecognized parts of the York succession and its offshore equivalents. Intensely deformed and altered Mississippian carbonate strata crop out in a small area at the western edge of the terrane. Metacarbonate rocks form all or part of several units within the blueschist- and greenschist-facies Nome Complex. The Layered sequence includes mafic meta¬igneous rocks and associated calcareous metaturbidites of Ordovician age as well as shallow-water Silurian dolostones. Scattered metacarbonate rocks are chiefly Cambrian, Ordovician, Silurian, and Devonian dolostones that formed in shallow, warm-water settings with locally restricted circulation and marbles of less constrained Paleozoic age. Carbonate metaturbidites occur on the northeast and southeast coasts and yield mainly Silurian and lesser Ordovician and Devonian conodonts; the northern succession also includes debris flows with meter-scale clasts and an argillite interval with Late Ordovician graptolites and lenses of radiolarian chert. Mafic igneous rocks at least partly of Early Devonian age are common in the southern succession. Carbonate rocks on Seward Peninsula experienced a range of deformational and thermal histories equivalent to those documented in the Brooks Range. Conodont color alteration indices (CAIs) from Seward Peninsula, like those from the Brooks Range, define distinct thermal provinces that likely reflect structural burial. Penetratively deformed high-pressure metamorphic rocks of the Nome Complex (CAIs ≥5) correspond to rocks of the Schist belt in the southern Brooks Range; both record subduction during early stages of the Jurassic–Cretaceous Brooks Range orogeny. Weakly metamorphosed to unmetamorphosed strata of the York terrane (CAIs mainly 2–5), like Brooks Range rocks in the Central belt and structural allochthons to the north, experienced moderate to shallow burial during the main phase of the Brooks Range orogeny. The nature of the contact between the York terrane and the Nome Complex is uncertain; it may be a thrust fault, an extensional surface, or a thrust fault later reactivated as an extensional fault. Lithofacies and biofacies data indicate that, in spite of their divergent Mesozoic histories, rocks of the York terrane and protoliths of the Nome Complex formed as part of the same lower Paleozoic carbonate platform. Stratigraphies in both

Lithostratigraphic, conodont, and other faunal links between lower Paleozoic strata in northern and central Alaska and northeastern Russia

USGS Publications Warehouse

Dumoulin, Julie A.; Harris, Anita G.; Gagiev, Mussa; Bradley, Dwight C.; Repetski, John E.

2002-01-01

Lower Paleozoic platform carbonate strata in northern Alaska (parts of the Arctic Alaska, York, and Seward terranes; herein called the North Alaska carbonate platform) and central Alaska (Farewell terrane) share distinctive lithologic and faunal features, and may have formed on a single continental fragment situated between Siberia and Laurentia. Sedimentary successions in northern and central Alaska overlie Late Proterozoic metamorphosed basement; contain Late Proterozoic ooid-rich dolostones, Middle Cambrian outer shelf deposits, and Ordovician, Silurian, and Devonian shallow-water platform facies, and include fossils of both Siberian and Laurentian biotic provinces. The presence in the Alaskan terranes of Siberian forms not seen in wellstudied cratonal margin sequences of western Laurentia implies that the Alaskan rocks were not attached to Laurentia during the early Paleozoic.The Siberian cratonal succession includes Archean basement, Ordovician shallow-water siliciclastic rocks, and Upper Silurian–Devonian evaporites, none of which have counterparts in the Alaskan successions, and contains only a few of the Laurentian conodonts that occur in Alaska. Thus we conclude that the lower Paleozoic platform successions of northern and central Alaska were not part of the Siberian craton during their deposition, but may have formed on a crustal fragment rifted away from Siberia during the Late Proterozoic. The Alaskan strata have more similarities to coeval rocks in some peri-Siberian terranes of northeastern Russia (Kotelny, Chukotka, and Omulevka). Lithologic ties between northern Alaska, the Farewell terrane, and the peri-Siberian terranes diminish after the Middle Devonian, but Siberian afµnities in northern and central Alaskan biotas persist into the late Paleozoic.

Progradational sequences in Miocene shoreline deposits, southeastern Caliente Range, California

USGS Publications Warehouse

Clifton, H. Edward

1981-01-01

An exceptionally well exposed marine-nonmarine transition in middle Miocene strata exists in the southeastern Caliente Range, California. About 50 individual progradational sequences form a succession that ranges in thickness from approximately 1000 m (where predominantly nonmarine) to more than 2500 m (where predominantly marine). Paleogreographic evidence in basalt flows near the top of the succession and in overlying fluvial deposists indicates that these middle Miocene strata were deposited across a north-northwest trending shoreline.A complete progradational sequence typically is several meters to a few tens of meters thick and includes strata that represent three intertonguing stratigraphic units. Individual sequences generally rest on a thin gravel deposit interpreted as a transgressive lag on an erosional surface. The gravel is overlain by structureless siltstone or fine-grained sandstone deposited at water depths where the rate of faunal mixing exceeded that of production of structures by physical processes. These rocks grade upward into bedded fine sandstone deposited closer to shore where physical processes exceeded bioturbation. Crossbedded lenses of coarse sand or fine gravel in the upper part of this facies suggest the presence of failry long-period surface waves. The bedded fine sandstone is sharply overlain by a crossbedded coarse sandstone facies that is interpreted as a combined offshore bar-rip channel-surf zone assemblage. Cross-strata dip dominantly offshore, suggesting substantial deposition from rip currents. A secondary, shore=parallel mode of cross-strata direction suggests longshore currents produced by surface waves from the northwest. The crossbedded coarse-grained sandstone grades upward into planar-bedded medium-grained sandstone that is interpreted as a beach foreshore. This facies grades upward through structureless medium-grained sandstone into nonmarine or lagoonal red and green mudstone of the Caliente Formation.The middle Miocene succession was deposited in a subsiding basin that was otherwise remarkably stable tectonically; the position of the strand line differed no more than a few kilometers through a period of 1 to 3 m.y. The average duration of the transgressive-regressive cycles, a few tens of thousands of years, together with their distribution in groups of three or four in the lower two-thirds of the succession, is consistent with the pattern of long-term climatic cycles produced by periodicity of the earth's solar orbit and may be related to eustatic sea level changes attendant to the development of the Antarctic ice cap. Changes in the pattern of progradation in the upper part of the succession and nearby basaltic eruptions may hav been precursors to the onset of movement along the San Andreas fault in this area 12-14 m.y. ago.

The Bowland Basin, NW England: Base metal mineralisation and its relationship to basin evolution

NASA Astrophysics Data System (ADS)

Gaunt, Jonathan Mark

The Bowland Basin of NW England is a Carboniferous half graben. The Basin was initiated in the Devonian and actively extended during the Carboniferous until the late Westphalian. From the late Westphalian to the early Permian the Bowland Basin underwent inversion in response to Hercynian collision tectonics. Renewed subsidence commenced in the Permian and continued until inversion in the Cenozoic. The sedimentary succession of the Bowland Basin is dominated by Carboniferous strata, but some Permo-Triassic strata are present. The basal sedimentary succession may be comprised of Devonian to early Dinantian syn-rift clastics. The main Dinantian succession is comprised of interbedded limestones, calcareous mudstones and clastic strata. The Dinantian strata include the Waulsortian-facies Clitheroe Limestone and the Limekiln Wood Limestone, both of which host mineralisation. The overlying Namurian is comprised of shales and sandstones. The diagenetic history of the Limekiln Wood Limestone and Waulsortian-facies Clitheroe Limestone in the Cow Ark-Marl Hill Moor district is a function of changes in the burial environment during the Carboniferous. Both exhibit a pre-basin inversion diagenetic sequence that changes with time from shallow to moderate burial depth cements. Late Carbonifeous basin inversion resulted in the formation of tectonic stylolites. Tectonic stylolitisation was postdated by dolomitisation and silicification. Dolomitisation and silicification are suggested to have taken place in the deep burial environment. The base metal mineralisation studied in this work comes from the Cow Ark- Marl Hill Moor district, which is sited on the present basin inversion axis. Mineralisation occurs as four distinct episodes (Period 1, Period 2, Period 3 and Post-Period 3) within a complex multigeneration vein suite. The vein suite, which postdates tectonic stylolitisation and hence end-Carboniferous basin inversion, is comprised of calcite, baroque dolomite, baroque ankerite and siderite. The veins, which are often spatially associated with faults, exhibit a variety of morphologies, and are largely hosted by hydraulic shear fractures. Compositional variations between the different vein carbonates occur with time and the calcites, baroque dolomites, baroque ankerites and siderites are interpreted to have had several different fluid sources. Fluids precipitating siderite, baroque dolomite and baroque ankerite may have been produced by clay mineral transformations and decarboxylation of organic matter within the calcareous strata. The multiple vein calcite generations belong to three MnO:FeO compositional classes, each occupying a specific paragenetic position. The trend from ferroan to manganoan calcite with time may be a consequence of calcite-forming fluids being derived from successively shallower depths within the sedimentary succession, or of increased permeation by meteoric fluids. (Abstract shortened by ProQuest.).

Middle Jurassic strata link Wallowa, Olds Ferry, and Izee terranes in the accreted Blue Mountains island arc, northeastern Oregon

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

White, J.D.L.; Vallier, T.; Stanley, G.D. Jr.

1992-08-01

Middle Jurassic strata atop the Wallowa terrane in northeastern Oregon link the Wallowa, Izee, and Olds Ferry terranes as related elements of a single long-lived and complex oceanic feature, the Blue Mountains island arc. Middle Jurassic strata in the Wallowa terrane include a dacitic ash-flow deposit and contain fossil corals and bivalves of North American affinity. Plant fossils in fluvial sandstones support a Jurassic age and indicate a seasonal temperate climate. Corals in a transgressive sequence traditionally overlying the fluvial units are of Bajocian age and are closely related to endemic varieties of the Western Interior embayment. They are unlikemore » Middle Jurassic corals in other Cordilleran terranes; their presence suggests that the Blue Mountains island arc first approached the North American craton at high paleolatitudes in Middle Jurassic time. The authors consider the Bajocian marine strata and underlying fluvial volcaniclastic units to be a basin-margin equivalent of the Izee terrane, a largely Middle Jurassic (Bajocian) succession of basinal volcaniclastic and volcanic rocks known to overlie the Olds Ferry and Baker terranes.« less

Deciphering evolutionary strata on plant sex chromosomes and fungal mating-type chromosomes through compositional segmentation.

PubMed

Pandey, Ravi S; Azad, Rajeev K

2016-03-01

Sex chromosomes have evolved from a pair of homologous autosomes which differentiated into sex determination systems, such as XY or ZW system, as a consequence of successive recombination suppression between the gametologous chromosomes. Identifying the regions of recombination suppression, namely, the "evolutionary strata", is central to understanding the history and dynamics of sex chromosome evolution. Evolution of sex chromosomes as a consequence of serial recombination suppressions is well-studied for mammals and birds, but not for plants, although 48 dioecious plants have already been reported. Only two plants Silene latifolia and papaya have been studied until now for the presence of evolutionary strata on their X chromosomes, made possible by the sequencing of sex-linked genes on both the X and Y chromosomes, which is a requirement of all current methods that determine stratum structure based on the comparison of gametologous sex chromosomes. To circumvent this limitation and detect strata even if only the sequence of sex chromosome in the homogametic sex (i.e. X or Z chromosome) is available, we have developed an integrated segmentation and clustering method. In application to gene sequences on the papaya X chromosome and protein-coding sequences on the S. latifolia X chromosome, our method could decipher all known evolutionary strata, as reported by previous studies. Our method, after validating on known strata on the papaya and S. latifolia X chromosome, was applied to the chromosome 19 of Populus trichocarpa, an incipient sex chromosome, deciphering two, yet unknown, evolutionary strata. In addition, we applied this approach to the recently sequenced sex chromosome V of the brown alga Ectocarpus sp. that has a haploid sex determination system (UV system) recovering the sex determining and pseudoautosomal regions, and then to the mating-type chromosomes of an anther-smut fungus Microbotryum lychnidis-dioicae predicting five strata in the non-recombining region of both the chromosomes.

Prevalence, Genotype Richness, and Coinfection Patterns of Hemotropic Mycoplasmas in Raccoons (Procyon lotor) on Environmentally Protected and Urbanized Barrier Islands.

PubMed

Volokhov, Dmitriy V; Hwang, Jusun; Chizhikov, Vladimir E; Danaceau, Heather; Gottdenker, Nicole L

2017-05-01

Raccoons ( Procyon lotor ) are successful urban adapters and hosts to a number of zoonotic and nonzoonotic pathogens, yet little is known about their hemoplasma infections and how prevalence varies across habitat types. This study identifies hemotropic Mycoplasma species infection in raccoons from urban and undisturbed habitats and compares hemoplasma infection in sympatric urban cats ( Felis catus ) from the same geographic region. We collected blood from raccoons ( n = 95) on an urban coastal island ( n = 37) and an undisturbed coastal island ( n = 58) and from sympatric urban cats ( n = 39) in Georgia, USA. Based on 16S rRNA gene amplification, 62.1% (59/95) of raccoons and 17.9% (7/39) of feral cats were positive for hemoplasma. There was a greater percentage of hemoplasma-infected raccoons on the undisturbed island (79.3% [46/58]) than on the urban island (35.1% [13/37]; χ 2 = 16.9, df = 1, P = 0.00004). Sequencing of the full-length 16S rRNA gene amplicons revealed six hemoplasma genotypes in raccoons, including five novel genotypes that were distinct from three known hemoplasma species identified in the sympatric cats. In addition, the hemoplasma genotypes detected in raccoons were not identified in sympatric cats or vice versa. Although all six hemoplasma genotypes were found in raccoons from urban and undisturbed islands, coinfection patterns differed between sites and among individuals, with the proportion of coinfected raccoons being greater in the undisturbed site. This study shows that raccoons are hosts for several novel hemoplasmas and that habitat type influences infection patterns. IMPORTANCE This study provides information about novel hemoplasmas identified in raccoons ( Procyon lotor ), which can be used for assessments of the prevalence of these hemoplasmas in raccoon populations and for future studies on the potential pathogenic impacts of these hemoplasmas on raccoon health. Raccoons from the undisturbed habitat had a higher prevalence of hemoplasma infection than urban raccoons. There does not appear to be cross-species transmission of hemotropic mycoplasmas between urban raccoons and feral cats. Raccoons appear to be hosts for several novel hemoplasmas, and habitat type influences infection patterns. Copyright © 2017 American Society for Microbiology.

Prevalence, Genotype Richness, and Coinfection Patterns of Hemotropic Mycoplasmas in Raccoons (Procyon lotor) on Environmentally Protected and Urbanized Barrier Islands

PubMed Central

Hwang, Jusun; Chizhikov, Vladimir E.; Danaceau, Heather

2017-01-01

ABSTRACT Raccoons (Procyon lotor) are successful urban adapters and hosts to a number of zoonotic and nonzoonotic pathogens, yet little is known about their hemoplasma infections and how prevalence varies across habitat types. This study identifies hemotropic Mycoplasma species infection in raccoons from urban and undisturbed habitats and compares hemoplasma infection in sympatric urban cats (Felis catus) from the same geographic region. We collected blood from raccoons (n = 95) on an urban coastal island (n = 37) and an undisturbed coastal island (n = 58) and from sympatric urban cats (n = 39) in Georgia, USA. Based on 16S rRNA gene amplification, 62.1% (59/95) of raccoons and 17.9% (7/39) of feral cats were positive for hemoplasma. There was a greater percentage of hemoplasma-infected raccoons on the undisturbed island (79.3% [46/58]) than on the urban island (35.1% [13/37]; χ2 = 16.9, df = 1, P = 0.00004). Sequencing of the full-length 16S rRNA gene amplicons revealed six hemoplasma genotypes in raccoons, including five novel genotypes that were distinct from three known hemoplasma species identified in the sympatric cats. In addition, the hemoplasma genotypes detected in raccoons were not identified in sympatric cats or vice versa. Although all six hemoplasma genotypes were found in raccoons from urban and undisturbed islands, coinfection patterns differed between sites and among individuals, with the proportion of coinfected raccoons being greater in the undisturbed site. This study shows that raccoons are hosts for several novel hemoplasmas and that habitat type influences infection patterns. IMPORTANCE This study provides information about novel hemoplasmas identified in raccoons (Procyon lotor), which can be used for assessments of the prevalence of these hemoplasmas in raccoon populations and for future studies on the potential pathogenic impacts of these hemoplasmas on raccoon health. Raccoons from the undisturbed habitat had a higher prevalence of hemoplasma infection than urban raccoons. There does not appear to be cross-species transmission of hemotropic mycoplasmas between urban raccoons and feral cats. Raccoons appear to be hosts for several novel hemoplasmas, and habitat type influences infection patterns. PMID:28258139

Review of Paleomagnetic Age Constraints of Mid-Continent Rift Strata, Upper Midwestern United States

NASA Astrophysics Data System (ADS)

Houlihan, E.; Runkel, A.; Feinberg, J. M.; Cowan, C. A.; Titus, S.

2016-12-01

The Keweenawan Supergroup consists of 1.1 Ga volcanic units and overlying km-thick sedimentary succession that are associated with the Midcontinent Rift (MR), one of the most prominent geologic features in the Precambrian basement rocks of the North American craton (Morey and Green, 1982; Ojakangas et al., 2001; Ojakangas and Dickas, 2002). Recent studies targeting the sedimentary sequences of the rift highlight a longstanding problem that limits the impact of their results. The studies are based on data collected from a sedimentary package of the Keweenawan Supergroup that is very poorly constrained in age. Sedimentary strata low in the succession are constrained by dated intercalated volcanics, or mineralization ages, that indicate syn-rift filling commenced at about 1087 Ma as volcanism was waning (Davis and Paces, 1990). However, km-thick younger strata within the rift are constrained in maximum age only by virtue of overlying Cambrian fossil-bearing units (Morey and Ojakangas, 1982). Thus, the bulk of the MR sedimentary succession has a range in possible age of about 500 Ma, and potentially is in places as young as Middle Cambrian. Paleomagnetic methods may hold the most promise to date the MR sedimentary succession. Widespread paleomagnetic studies have been conducted on the igneous rocks of the rift, and several previous studies have used paleomagnetic techniques to date the sedimentary units as well (Dubois, 1962; Henry et al., 1976; Elmore and Van der Voo, 1978; Roy and Robertson, 1978; Halls and Palmer, 1981; Palmer et al., 1981; Watts, 1981; McCabe and Van der Voo, 1982; Diehl and Haig, 1994; Kulakov et al., 2013 and others). These authors generally considered the paleomagnetic signatures to be consistent with a Mesoproterozoic age for both the igneous and sedimentary rocks of the rift. Recently, however, authors have suggested that the uppermost sedimentary units are much younger in age, based on a combination of zircon and paleomagnetic analysis (Malone et al., 2016). Here, we present new paleomagnetic data collected in 2015, and combine it with previous paleomagnetic studies to synthesize all paleomagnetic data on the Mid-Continent Rift strata and provide suggestions for future studies to determine the age and correlation of the units.

Development of an Assessment Framework for Restored Forested Wetlands

Treesearch

Randall K. Kolka; Carl C. Trettin; E.A. Nelson

1998-01-01

Development of an assessment framework and associated indicators that can be used to evaluate the effectiveness of a wetland restoration is critical to demonstrating the sustainability of restored sites. An interdisciplinary approach was developed to assess how succession is proceeding on a restored bottomland site in South Carolina relative to an undisturbed...

Influence of restoration and succession on bottomland hardwood hydrology

Treesearch

Randy K. Kolka; J. H. Singer; C. R. Coppock; W. P. Casey; C. C. Trettin

2000-01-01

The hydrologic pathways of four bottomland hardwood wetland sites were investigated with transects consisting of nests of shallow wells and piezometers. Sites included a disturbed but recently restored system, two disturbed systems that are recovering naturally and a relatively undisturbed reference site. Water table elevations in both uplands and bottomlands were...

Detrital zircon geochronology of pre- and syncollisional strata, Acadian orogen, Maine Appalachians

USGS Publications Warehouse

Bradley, Dwight C.; O'Sullivan, Paul B.

2017-01-01

The Central Maine Basin is the largest expanse of deep-marine, Upper Ordovician to Devonian metasedimentary rocks in the New England Appalachians, and is a key to the tectonics of the Acadian Orogeny. Detrital zircon ages are reported from two groups of strata: (1) the Quimby, Rangeley, Perry Mountain and Smalls Falls Formations, which were derived from inboard, northwesterly sources and are supposedly older; and (2) the Madrid, Carrabassett and Littleton Formations, which were derived from outboard, easterly sources and are supposedly younger. Deep-water deposition prevailed throughout, with the provenance shift inferred to mark the onset of foredeep deposition and orogeny. The detrital zircon age distribution of a composite of the inboard-derived units shows maxima at 988 and 429 Ma; a composite from the outboard-derived units shows maxima at 1324, 1141, 957, 628, and 437 Ma. The inboard-derived units have a greater proportion of zircons between 450 and 400 Ma. Three samples from the inboard-derived group have youngest age maxima that are significantly younger than the nominal depositional ages. The outboard-derived group does not share this problem. These results are consistent with the hypothesised provenance shift, but they signal potential problems with the established stratigraphy, structure, and (or) regional mapping. Shallow-marine deposits of the Silurian to Devonian Ripogenus Formation, from northwest of the Central Maine Basin, yielded detrital zircons featuring a single age maximum at 441 Ma. These zircons were likely derived from a nearby magmatic arc now concealed by younger strata. Detrital zircons from the Tarratine Formation, part of the Acadian foreland-basin succession in this strike belt, shows age maxima at 1615, 980 and 429 Ma. These results are consistent with three episodes of zircon recycling beginning with the deposition of inboard-derived strata of the Central Maine Basin, which were shed from post-Taconic highlands located to the northwest. Next, southeasterly parts of this succession were deformed in the Acadian orogeny, shedding detritus towards the northwest into what remained of the basin. Finally, by Pragian time, all strata in the Central Maine Basin had been deformed and detritus from this new source accumulated as the Tarratine Formation in a new incarnation of the foreland basin. Silurian-Devonian strata from the Central Maine Basin have similar detrital zircon age distributions to coeval rocks from the Arctic Alaska and Farewell terranes of Alaska and the Northwestern terrane of Svalbard. We suggest that these strata were derived from different segments of the 6500-km-long Appalachian-Caledonide orogen.

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

Handford, C.R.

Exploration is increasingly dependent upon obtaining credible stratigraphic interpretations of seismic data. With respect to carbonate platforms, two of the most important seismic-imaging and interpretation problems are (1) distinguishing between lowstand unconformities and drowning unconformities, and (2) recognizing paleokarst reservoirs. Lowstand unconformities vs. drowning unconformities. Many contend that onlapping wedges of strata above sequence boundaries but below the previous shelf break comprise the lowstand systems tract. An alternative view is that onlapping wedges do not record sea level falls, but instead chronicle sea level rises and platform demise. A Mississippian carbonate ramp exposed along the southern margin of North Americamore » is flanked by a siliciclastic lowstand wedge and overlain by a drowning succession of black shales. This dual history of lowstand exposure and drowning formed two baselap surfaces, which lie so close to each other on the shelf that seismic dissemination is almost impossible. The paradox is that although the ramp was terminated by drowning, the visible seismic baselap was due to low-stand exposure. Numerous large fields around the world produce from carbonate reservoirs with a moderate to strong paleokarst overprint. Their discoveries, however, were structurally driven and rarely based upon predrill knowledge of paleokarst systems. In fact, there has been little effort to determine how to recognize paleocave systems in seismic reflection data. To narrow this gap, the sedimentary fill and stratal geometries of modern cave systems were examined and modeled seismically. The models show a passage from continuous reflections in the undisturbed country rock to discontinuous reflections inclined toward the cavern core. Velocity pull-ups and pull-downs are significant where velocity and density contrasts between the country rock and collapsed chamber are important.« less

Overview of the potential and identified petroleum source rocks of the Appalachian basin, eastern United States: Chapter G.13 in Coal and petroleum resources in the Appalachian basin: distribution, geologic framework, and geochemical character

USGS Publications Warehouse

Coleman, James L.; Ryder, Robert T.; Milici, Robert C.; Brown, Stephen; Ruppert, Leslie F.; Ryder, Robert T.

2014-01-01

The Appalachian basin is the oldest and longest producing commercially viable petroleum-producing basin in the United States. Source rocks for reservoirs within the basin are located throughout the entire stratigraphic succession and extend geographically over much of the foreland basin and fold-and-thrust belt that make up the Appalachian basin. Major source rock intervals occur in Ordovician, Devonian, and Pennsylvanian strata with minor source rock intervals present in Cambrian, Silurian, and Mississippian strata.

Facies analysis and sequence stratigraphic framework of upper Campanian strata (Neslen and Mount Garfield formations, Bluecastle Tongue of the Castlegate sandstone, and Mancos shale), Eastern Book cliffs, Colorado and Utah

USGS Publications Warehouse

Kirschbaum, Mark A.; Hettinger, Robert D.

2004-01-01

Facies and sequence-stratigraphic analysis identifies six high-resolution sequences within upper Campanian strata across about 120 miles of the Book Cliffs in western Colorado and eastern Utah. The six sequences are named after prominent sandstone units and include, in ascending order, upper Sego sequence, Neslen sequence, Corcoran sequence, Buck Canyon/lower Cozzette sequence, upper Cozzette sequence, and Cozzette/Rollins sequence. A seventh sequence, the Bluecastle sequence, is present in the extreme western part of the study area. Facies analysis documents deepening- and shallowing- upward successions, parasequence stacking patterns, downlap in subsurface cross sections, facies dislocations, basinward shifts in facies, and truncation of strata.All six sequences display major incision into shoreface deposits of the Sego Sandstone and sandstones of the Corcoran and Cozzette Members of the Mount Garfield Formation. The incised surfaces represent sequence-boundary unconformities that allowed bypass of sediment to lowstand shorelines that are either attached to the older highstand shorelines or are detached from the older highstand shorelines and located southeast of the main study area. The sequence boundary unconformities represent valley incisions that were cut during successive lowstands of relative sea level. The overlying valley-fill deposits generally consist of tidally influenced strata deposited during an overall base level rise. Transgressive surfaces can be traced or projected over, or locally into, estuarine deposits above and landward of their associated shoreface deposits. Maximum flooding surfaces can be traced or projected landward from offshore strata into, or above, coastal-plain deposits. With the exception of the Cozzette/Rollins sequence, the majority of coal-bearing coastal-plain strata was deposited before maximum flooding and is therefore within the transgressive systems tracts. Maximum flooding was followed by strong progradation of parasequences and low preservation potential of coastal-plain strata within the highstand systems tract. The large incised valleys, lack of transgressive retrogradational parasequences, strong progradational nature of highstand parasequences, and low preservation of coastal-plain strata in the highstand systems tracts argue for relatively low accommodation space during deposition of the Sego, Corcoran, and Cozzette sequences. The Buck Canyon/Cozzette and Cozzette/Rollins sequences contrast with other sequences in that the preservation of retrogradational parasequences and the development of large estuaries coincident with maximum flooding indicate a relative increase in accommodation space during deposition of these strata. Following maximum flooding, the Buck Canyon/Cozzette sequence follows the pattern of the other sequences, but the Cozzette/Rollins sequence exhibits a contrasting offlapping pattern with development of offshore clinoforms that downlap and eventually parallel its maximum flooding surface. This highstand systems tract preserves a thick coal-bearing section where the Rollins Sandstone Member of the Mount Garfield Formation parasequences prograde out of the study area, stepping up as much as 800 ft stratigraphically over a distance of about 90 miles. This progradational stacking pattern indicates a higher accommodation space and increased sedimentation rate compared to the previous sequences.

Seventy years of forest growth and community dynamics in an undisturbed northern hardwood forest

Treesearch

Jennifer Pontius; Joshua M. Halman; Paul G. Schaberg

2016-01-01

Long-term forest inventories provide a unique opportunity to quantify changes in forest structure and evaluate how changes compare with current stand development models. An examination of a 70 year record at the Bartlett Experimental Forest, New Hampshire, indicated that although species abundances have primarily changed as expected under natural succession, some...

The stratigraphy of the southern Pab Range, Pakistan

NASA Astrophysics Data System (ADS)

White, H. J.

The Cretaceous strata exposed in the southern Pab Range, southeast Baluchistan, Pakistan is investigated. It records the precollision deposition history of the Indo-Pakistani continental shelf. The strata comprise two depositional successions, namely, The Early to Late Cretaceous Sembar-Goru-Parh sequence and the Maestrichtian Mughal Kot-Pab sequence. The former began with deposition of black shales on the continental slope (Sembar Formation), succeeded by calcareous shale, marl and micstone of outer shelf origin (Goru Formation), and ended with inner shelf platform carbonates (Parh Limestone). These deep to shallow water lithofacies prograted westward over the continental shelf of the north-advancing Subcontinent. The Mughal Kot-Pab propagation contains the first significant influx of terrigenous sand reaching the western portion of the continental shelf. Deposition environments in the Mughal Kot Formation include inner shelf, prodelta, delta front and distributary channel. A thick succession of shoreface cycles comprises the Pab sandstone.

Evidence for Mojave-Sonora megashear-Systematic left-lateral offset of Neoproterozoic to Lower Jurassic strata and facies, western United States and northwestern Mexico

USGS Publications Warehouse

Stewart, John H.

2005-01-01

Major successions as well as individual units of Neoproterozoic to Lower Jurassic strata and facies appear to be systematically offset left laterally from eastern California and western Nevada in the western United States to Sonora, Mexico. This pattern is most evident in units such as the "Johnnie oolite," a 1- to 2-m-thick oolite of the Neoproterozoic Rainstorm Member of the Johnnie Formation in the western United States and of the Clemente Formation in Sonora. The pattern is also evident in the Lower Cambrian Zabriskie Quartzite of the western United States and the correlative Proveedora Quartzite in Sonora. Matching of isopach lines of the Zabriskie Quartzite and Proveedora Quartzite suggests ???700-800 km of left-lateral offset. The offset pattern is also apparent in the distribution of distinctive lithologic types, unconformities, and fossil assemblages in other rocks ranging in age from Neoproterozoic to Early Jurassic. In the western United States, the distribution of facies in Neoproterozoic and Paleozoic strata indicates that the Cordilleran miogeocline trends north-south. A north-south trend is also suggested in Sonora, and if so is compatible with offset of the miogeocline but not with the ideas that the miogeocline wrapped around the continental margin and trends east-west in Sonora. An imperfect stratigraphic match of supposed offset segments along the megashear is apparent. Some units, such as the "Johnnie oolite" and Zabriskie-Proveedora, show almost perfect correspondence, but other units are significantly different. The differences seem to indicate that the indigenous succession of the western United States and offset segments in Mexico were not precisely side by side before offset but were separated by an area-now buried, eroded, or destroyed-that contained strata of intermediate facies. ?? 2005 Geological Society of America.

A Polymer Plugging Gel for the Fractured Strata and Its Application

PubMed Central

Fan, Xiangyu; Zhao, Pengfei; Zhang, Qiangui; Zhang, Ting; Zhu, Kui; Zhou, Chenghua

2018-01-01

Well leakage of fractured strata is a tricky problem while drilling. This unwieldy problem is usually caused by the poor formation of the cementing degree, the staggered-mesh of the fracture, and the low bearing capacity of the formation, which can also lead to a narrow and even unsafe window of drilling fluid density. For fractured strata, the normal plugging material has the disadvantages of unsuitable size and low strength, resulting in unsuccessful first time plugging and an increase in cost. Therefore, we developed a polymer plugging gel for the fractured strata, named XNGJ-3. XNGJ-3 is mainly made of an acrylamide monomer and is accompanied by the reactive monomers of carboxyl and hydroxyl as ingredients. XNGJ-3 has a low viscosity before gelling. At 80 °C it becomes gelled, and the gelling time was controlled within the required time of the practical application. These conditions are beneficial for making the plugging material enter the crossing fracture smoothly and occlude the fracture. XNGJ-3 also has a good deformability and can avoid being damaged during the process of fracture closure. The well leakage simulated experiment revealed that the bearing capacity of this material can reach 21 MPa and the inverse bearing capacity can reach 20 MPa. These strengths are more than twice that of common polymer plugging gels. Finally, three leaked wells in the fractured strata of the Sichuan Basin were used to verify the plugging effect of XNGJ-3. Compared with other common plugging materials, XNGJ-3 has the advantages of having a higher success rate of first time plugging, a lower economic cost, a shorter work time, and so forth, which indicate that this plugging material has a good engineering application value in dealing with well leakage of fractured strata. PMID:29883407

Reclamation after oil and gas development does not speed up succession or plant community recovery in big sagebrush ecosystems in Wyoming

USGS Publications Warehouse

Rottler, Caitlin M.; Burke, Ingrid C.; Palmquist, Kyle A.; Bradford, John B.; Lauenroth, William K.

2018-01-01

Article for intended outlet: Restoration Ecology. Abstract: Reclamation is an application of treatment(s) following a disturbance to promote succession and accelerate the return of target conditions. Previous studies have framed reclamation in the context of succession by studying its effectiveness in re-establishing late-successional plant communities. Re-establishment of these plant communities is especially important and potentially challenging in regions such as drylands and shrub steppe ecosystems where succession proceeds slowly. Dryland shrub steppe ecosystems are frequently associated with areas rich in fossil-fuel energy sources, and as such the need for effective reclamation after disturbance from fossil-fuel-related energy development is great. Past research in this field has focused primarily on coal mines; few researchers have studied reclamation after oil and gas development. To address this research gap and to better understand the effect of reclamation on rates of succession in dryland shrub steppe ecosystems, we sampled oil and gas wellpads and adjacent undisturbed big sagebrush plant communities in Wyoming, USA and quantified the extent of recovery for major functional groups on reclaimed and unreclaimed (recovered via natural succession) wellpads relative to the undisturbed plant community. Reclamation increased the rate of recovery for all forb and grass species as a group and for perennial grasses, but did not affect other functional groups. Rather, analyses comparing recovery to environmental variables and time since wellpad abandonment showed that recovery of other groups were affected primarily by soil texture and time since wellpad abandonment. This is consistent with studies in other ecosystems where reclamation has been implemented, suggesting that reclamation may not help re-establish late-successional plant communities more quickly than they would re-establish naturally.

Bidirectional recovery patterns of Mojave Desert vegetation in an aqueduct pipeline corridor after 36 years: II. Annual plants

USGS Publications Warehouse

Berry, Kristin H.; Mack, Jeremy S.; Weigand, James F.; Gowan, Timothy A.; LaBerteaux, Denise

2015-01-01

We studied recovery of winter annual plants in a 97-m wide disturbed aqueduct corridor in the Mojave Desert 36 years after construction. We established plots at 0, 20, and 40 m from the road verge at the corridor center and at 100 m in undisturbed vegetation. We recorded 47 annual species, of which 41 were native and six were exotic. Exotic species composed from 64 to 91% of total biomass. We describe a bilateral process of recovery: from the road verge to the outward edge of the corridor and from undisturbed habitat into the corridor. Native annual plants significantly increased in richness from road verge to undisturbed vegetation, but not in density, biomass, or cover. In contrast, exotic annual plants increased in density, biomass, cover and richness with increasing distance from the road verge. The species of colonizing shrubs and type of canopy cover affected density, biomass, and richness of annuals. Species composition of native annuals differed significantly by distance, suggesting secondary succession. In general, native annuals were closer to achieving recovery on the 40-m plots than at the road verge. Recovery estimates were in centuries and dependent on location, canopy type, and whether considering all annuals or natives only.

Landscape variation in species diversity and succession as related to topography, soils and human disturbance

Treesearch

Jeffery N. Pearcy; David M. Hix; Stacy A. Drury

1995-01-01

Three hundred and thirty-two plots have been sampled on the Wayne National Forest of southeastern Ohio, for the purpose of developing an ecological classification system (ECS). The ECS will be based on the herbaceous and woody vegetation, soils and topography of mature (80-140 year-old), relatively-undisturbed forests. Species diversity changes little across this...

Posteruption arthropod succession on the Mount St. Helens volcano: the ground-dwelling beetle fauna (Coleoptera).

Treesearch

R.R. Parmenter; C.M. Crisafulli; N. Korbe; G. Parsons; M. Edgar; J.A. MacMahon

2005-01-01

The 1980 eruptions of Mount St. Helens created a complex mosaic of disturbance types over a 600 km2 area. From 1980 through 2000 we monitored beetle species relative abundance and faunal composition of assemblages at undisturbed reference sites and in areas subjected to tephra-fall, blowdown, and pyroclastic flow volcanic disturbance. We...

Differences in the impacts of formal and informal recreational trails on urban forest loss and tree structure.

PubMed

Ballantyne, Mark; Pickering, Catherine Marina

2015-08-15

Recreational trails are one of the most common types of infrastructure used for nature-based activities such as hiking and mountain biking worldwide. Depending on their design, location, construction, maintenance and use, these trails differ in their environmental impacts. There are few studies, however, comparing the impacts of different trail types including between formal management-created trails and informal visitor-created trails. Although both types of trails can be found in remote natural areas, dense networks of them often occur in forests close to cities where they experience intense visitor use. To assess the relative impacts of different recreational trails in urban forests, we compared the condition of the trail surface, loss of forest strata and changes in tree structure caused by seven types of trails (total network 46.1 km) traversing 17 remnants of an endangered urban forest in Australia. After mapping and classifying all trails, we assessed their impact on the forest condition at 125 sites (15 sites per trail type, plus 15 control sites within undisturbed forest). On the trail sites, the condition of the trail surface, distance from the trail edge to four forest strata (litter, understory, midstorey and tree cover) and structure of the tree-line were assessed. Informal trails generally had poorer surface conditions and were poorly-designed and located. Per site, formal and informal trails resulted in similar loss of forest strata, with wider trails resulting in greater loss of forest. Because there were more informal trails, however, they accounted for the greatest cumulative forest loss. Structural impacts varied, with the widest informal trails and all formal hardened trails resulting in similar reductions in canopy cover and tree density but an increase in saplings. These structural impacts are likely a function of the unregulated and intense use of large informal trails, and disturbance from the construction and maintenance of formal trails. The results demonstrate that different types of recreational trails vary in the type and range of impacts they cause to forests. They highlight the importance of careful consideration towards management options when dealing with trail networks especially in areas of high conservation value. Copyright © 2015 Elsevier Ltd. All rights reserved.

A Case Study on the Strata Movement Mechanism and Surface Deformation Regulation in Chengchao Underground Iron Mine

NASA Astrophysics Data System (ADS)

Cheng, Guanwen; Chen, Congxin; Ma, Tianhui; Liu, Hongyuan; Tang, Chunan

2017-04-01

The regular pattern of surface deformation and the mechanism of underground strata movement, especially in iron mines constructed with the block caving method, have a great influence on infrastructure on the surface, so they are an important topic for research. Based on the engineering geology conditions and the surface deformation and fracture features in Chengchao Iron Mine, the mechanism of strata movement and the regular pattern of surface deformation in the footwall were studied by the geomechanical method, and the following conclusions can be drawn: I. The surface deformation process is divided into two stages over time, i.e., the chimney caving development stage and the post-chimney deformation stage. Currently, the surface deformation in Chengchao Iron Mine is at the post-chimney deformation stage. II. At the post-chimney deformation stage, the surface deformation and geological hazards in Chengchao Iron Mine are primarily controlled by the NWW-trending joints, with the phenomenon of toppling deformation and failure on the surface. Based on the surface deformation characteristics in Chengchao Iron Mine, the surface deformation area can be divided into the following four zones: the fracture extension zone, the fracture closure zone, the fracture formation zone and the deformation accumulation zone. The zones on the surface can be determined by the surface deformation characteristics. III. The cantilever beams near the chimney caving area, caused by the NWW-trending joints, have been subjected to toppling failure. This causes the different deformation and failure mechanisms in different locations of the deep rock mass. The deep rock can be divided into four zones, i.e., the fracture zone, fracture transition zone, deformation zone and undisturbed zone, according to the different deformation and failure mechanisms. The zones in the deep rock are the reason for the zones on the surface, so they can be determined by the zones on the surface. Through these findings, the degree of damage to the infrastructure in different locations can be determined based on the surface deformation zones. As the mining continues deeper, the development regulation of the zones on the surface and in deep rock mass can be further studied based on the zones in the deep rock.

Undisturbed upright stance control in the elderly: Part 2. Postural-control impairments of elderly fallers.

PubMed

Berger, L; Chuzel, M; Buisson, G; Rougier, P

2005-09-01

A common way of predicting falling risks in elderly people can be to study center of pressure (CP) trajectories during undisturbed upright stance maintenance. By estimating the difference between CP and center of gravity (CG) motions (CP - CGv), one can estimate the neuromuscular activity. The results of this study, which included 34 sedentary elderly persons aged over 75 years (21 fallers and 13 nonfallers), demonstrated significantly increased CGh and CP - CGv motions in both axes for the fallers. In addition, the fallers presented larger CGh motions in the mediolateral axis, suggesting an enlarged loading-unloading mechanism, which could have reflected the adoption of a step-initiating strategy. As highlighted by fractional Brownian motion modeling, the distance covered by the CP - CGv motions before the successive control mechanisms switched was enhanced for the fallers in both axes, therefore increasing the risk that the CG would be outside of the base of support.

LBA-ECO TG-07 Trace Gas Fluxes, Undisturbed and Logged Sites, Para, Brazil: 2000-2002

Treesearch

M.M. Keller; R.K. Varner; J.D. Dias; H.S. Silva; P.M. Crill; Jr. de Oliveira; G.P. Asner

2009-01-01

Trace gas fluxes of carbon dioxide, methane, nitrous oxide, and nitric oxide were measured manually at undisturbed and logged forest sites in the Tapajos National Forest, near Santarem, Para, Brazil. Manual measurements were made approximately weekly at both the undisturbed and logged sites. Fluxes from clay and sand soils were completed at the undisturbed sites....

Reproductive strategy of the intertidal seagrass Zostera japonica under different levels of disturbance and tidal inundation

NASA Astrophysics Data System (ADS)

Suonan, Zhaxi; Kim, Seung Hyeon; Qin, Le-Zheng; Lee, Kun-Seop

2017-10-01

Zostera japonica populations along the coastline of the northwestern Pacific Ocean are declining, mainly due to anthropogenic and natural disturbances. Although reproductive strategy is an important factor in achieving population persistence, changes in the reproductive strategy of Z. japonica under anthropogenic disturbances and tidal stresses are largely unknown. Thus, the duration and frequency of flowering, reproductive effort, potential seed production, and seed density in sediments were measured at three study stations (undisturbed upper, undisturbed lower, and disturbed stations), which were classified based on the levels of inundation stress and clamming activity, in monospecific meadows of Z. japonica on the southern coast of Korea. The flowering duration was approximately six months in the disturbed station, with disturbance due to clam harvesting, whereas the duration was about five months in the undisturbed lower station, and only three months in the undisturbed upper station. The maximum flowering frequency was 25.5% in the disturbed station, which was approximately 4- and 2-fold higher than in the undisturbed upper (6.1%) and lower (12.3%) stations, respectively. A similar trend in reproductive effort was also found among the three study stations. Potential seed production was 7850, 6220, and 1560 seeds m-2 in the disturbed, undisturbed lower, and undisturbed upper stations, respectively. The annual maximum seed density in sediments was also higher in the disturbed and undisturbed lower stations than in the undisturbed upper station, but the densities were relatively low (ranging from 71 to 254 seeds m-2) at all three study stations. It was found that the allocation to sexual reproduction was highest in the disturbed station, followed by the undisturbed lower station, and lowest in the undisturbed upper station, suggesting that sexual reproduction in Z. japonica tends to be enhanced under disturbed and inundated environmental conditions for population persistence.

Establishing benchmark monitoring points in wilderness: successes and challenges

Treesearch

Charles G. Johnson

2000-01-01

The Western United States has a rich heritage of biological diversity within the wilderness areas. To access human disturbances compared to human-undisturbed sites, the tool of “benchmarking” is used, where sites are compared over time. The resulting data and photographic records are the basis of monitoring used by land managers. Examples are given for three locations...

Use of fish community data to evaluate restoration success of a riparian stream

Treesearch

Michael H. Paller; Marcel J.M. Reichert; John M. Dean; John C. Seigle

2000-01-01

From 1985 to 1988, stream and riparian habitats in Pen branch and Four Mile branch began recovering from deforestation caused by the previous release of hot water from nuclear reactors. The Pen branch corridor was replanted with wetland trees in 1995 to expedite recovery and restore the Pen branch ecosystem. Pen branch, Four Mile branch, and two relatively undisturbed...

Physical simulation and theoretical evolution for ground fissures triggered by underground coal mining

PubMed Central

Yu, Xiang; Yang, Yi; Yang, Zeng-Qiang

2018-01-01

Underground coal mining activities are prone to cause movement and breakage in geological strata and also lead to mining subsidence and even ground fissures. Along the direction working panel advancing, ground fissures may occur in roof in front and/or behind working panel. However, the investigations of previous similarity tests in lab only emphasize on the region behind working panel. By improving strata material property in construction and mounting artificial pressure devices, two physical simulation tests were conducted and successfully investigated the simulated results. Then, the mechanical model of “cantilever beam and elastic foundation beam” was proposed to calculate the stress distribution and the crack initiation angle in overlying strata and it well explains the mechanisms of ground fissures generation and propagation. Results show that, the maximum internal force in roof always occurred in front of working panel. However, because the void space in gob due to excavation is large enough to cause the bend and rotation of roof strata, compare to the triaxially compressed region in front of working panel, the roof always broke off at some positions above gob since the stress concentration resulting from such bend and rotation of strata could easily reach the limit strength of strata rocks. Also, the length of cantilever beam changed dynamically as respect to the panel advancing and the breakage intervals. Thus, the breakage position where the internal force first reached the limit tensile strength is not fixed and there will be two different kinds of relative positions between the crack initiation point and the working panel. The crack initiation direction is always perpendicular to the internal force, and the crack propagation direction is affected by the initiation angle, overburden-separation degree and the position of the hydraulic shields. If there is no overburden-separation or less, the roofs will break off as a composite beam and the propagation direction will be roughly along the central line between the initial broken point and the support position. Otherwise, the roof strata will bend with the support shields moving forward, then the fracture angle will be close to the initiation angle and the fault surface will be stepped. PMID:29513703

Physical simulation and theoretical evolution for ground fissures triggered by underground coal mining.

PubMed

Yang, Jing-Hu; Yu, Xiang; Yang, Yi; Yang, Zeng-Qiang

2018-01-01

Underground coal mining activities are prone to cause movement and breakage in geological strata and also lead to mining subsidence and even ground fissures. Along the direction working panel advancing, ground fissures may occur in roof in front and/or behind working panel. However, the investigations of previous similarity tests in lab only emphasize on the region behind working panel. By improving strata material property in construction and mounting artificial pressure devices, two physical simulation tests were conducted and successfully investigated the simulated results. Then, the mechanical model of "cantilever beam and elastic foundation beam" was proposed to calculate the stress distribution and the crack initiation angle in overlying strata and it well explains the mechanisms of ground fissures generation and propagation. Results show that, the maximum internal force in roof always occurred in front of working panel. However, because the void space in gob due to excavation is large enough to cause the bend and rotation of roof strata, compare to the triaxially compressed region in front of working panel, the roof always broke off at some positions above gob since the stress concentration resulting from such bend and rotation of strata could easily reach the limit strength of strata rocks. Also, the length of cantilever beam changed dynamically as respect to the panel advancing and the breakage intervals. Thus, the breakage position where the internal force first reached the limit tensile strength is not fixed and there will be two different kinds of relative positions between the crack initiation point and the working panel. The crack initiation direction is always perpendicular to the internal force, and the crack propagation direction is affected by the initiation angle, overburden-separation degree and the position of the hydraulic shields. If there is no overburden-separation or less, the roofs will break off as a composite beam and the propagation direction will be roughly along the central line between the initial broken point and the support position. Otherwise, the roof strata will bend with the support shields moving forward, then the fracture angle will be close to the initiation angle and the fault surface will be stepped.

[Adaptation of control mechanisms involved in upright undisturbed stance maintenance during prolonged darkness].

PubMed

Rougier, P

2003-04-01

To assess to which extent the non visual somato-sensorial information may, through a recalibration process, induce a reorganisation by the central nervous system to control undisturbed upright stance. Ten healthy adults were placed in complete darkness for a 24 min period. Their postural performance was recorded through a force platform on which they were required to stand still at regular intervals. Centre of Pressure (CP) displacements, recorded from the platform, were modelled as fractional brownian motion. Through this analysis, one may objectively assess from which distance and for how long the corrective process is initiated with the aim of slowing and retrace its steps. In addition, the degree to which the CP trajectories are successively controlled was determined. Once in complete darkness, an increase of the mean time intervals (Delta(t)) before the corrective process intervenes was observed, the effect being mostly significant for the mediolateral direction. In parallel, the mean distances covered at this Delta(t) were slightly affected for both mediolateral and anteroposterior directions. Lastly, the degree to which the CP trajectories are controlled tended to decrease. These data suggest a reorganisation of the control mechanisms called into play for maintaining an undisturbed upright stance, thus implying participation of the central nervous system. This short-term adaptation is discussed on the basis of our knowledge of long term adaptations previously observed in blind individuals, and also in a rehabilitation perspective.

Recent sedimentological studies of the Murray and Stimson formations and their implications for Gale crater evolution, Mars

NASA Astrophysics Data System (ADS)

Gupta, Sanjeev; Fedo, Chris; Grotzinger, John; Edgett, Ken; Vasavada, Ashwin

2017-04-01

The Mars Science Laboratory (MSL) Curiosity rover has been exploring sedimentary rocks on the lower north slope of Aeolis Mons since August 2014. Previous work has demonstrated a succession of sedimentary rock types deposited dominantly in river-delta settings (Bradbury group), and interfingering/overlying contemporaneous/younger lake settings (Murray formation, Mt. Sharp group). The Murray formation is unconformably overlain by the Stimson formation, an ancient aeolian sand lithology. Here, we describe the MSL team's most recent sedimentological findings regarding the Murray and Stimson formations. The Murray formation is of the order of 200 meters thick and formed dominantly of mudstones. The mudstone facies, originally identified at the Pahrump Hills field site, show abundant fine-scale planar laminations throughout the Murray formation succession and is interpreted to record deposition in an ancient lake system in Gale crater. Since leaving the Naukluft Plateau (Stimson formation rocks) and driving south-southeastwards and progressive stratigraphically upwards through the Murray succession, we have recognised a variety of additional facies have been recognized that indicate variability in the overall palaeoenvironmental setting. These facies include (1) cross-bedded siltstones to very fine-grained sandstones with metre-scale troughs that might represent aeolian sedimentation; (2) a heterolithic mudstone-sandstone facies with laminated fine-grained strata, cm-scale ripple cross-laminations in siltstone or very fine sandstone, and dm-scale cross-stratified siltstone and very fine grained sandstone. The palaeoenvironmental setting for the second facies remains under discussion. Our results show that Gale crater hosted lakes systems for millions to tens of millions of years, perhaps punctuated by drier intervals. Murray strata are unconformably overlain by the Stimson formation. Stimson outcrops are typically characterized by cross-bedded sandstones with cross-sets ranging between 40-80 cm thick (Fig. 2). Within the sets, cross-strata comprise repetitive laminations that are a few millimeters thick and typically sub-parallel. Cross-laminations downlap onto the underlying bounding surface with an asymptotic profile and are truncated at their top by an overlying bounding surface. Palaeocurrent analysis based on measurements of 117 foreset azimuths indicate a wind regime that drove dune migration towards the northeast. Cross sets are separated by erosional bounding surfaces, which are interpreted to represent interdune surfaces, which were formed by migrating dunes as they climbed over the stoss slope of a preceding dune, eroding its stoss and upper part of the lee slope. From analysis of the sedimentary architecture, and comparison with terrestrial aeolian strata, we interpret the Stimson formation to represent sands deposited in a dry-aeolian dune system. In summary, sedimentary observations by the Curiosity rover record a diverse range of palaeoenvironments and a rich geological history in strata preserved in lower Aeolis Mons.

Evaluating equilibrium and non-equilibrium transport of bromide and isoproturon in disturbed and undisturbed soil columns.

PubMed

Dousset, S; Thevenot, M; Pot, V; Simunek, J; Andreux, F

2007-12-07

In this study, displacement experiments of isoproturon were conducted in disturbed and undisturbed columns of a silty clay loam soil under similar rainfall intensities. Solute transport occurred under saturated conditions in the undisturbed soil and under unsaturated conditions in the sieved soil because of a greater bulk density of the compacted undisturbed soil compared to the sieved soil. The objective of this work was to determine transport characteristics of isoproturon relative to bromide tracer. Triplicate column experiments were performed with sieved (structure partially destroyed to simulate conventional tillage) and undisturbed (structure preserved) soils. Bromide experimental breakthrough curves were analyzed using convective-dispersive and dual-permeability (DP) models (HYDRUS-1D). Isoproturon breakthrough curves (BTCs) were analyzed using the DP model that considered either chemical equilibrium or non-equilibrium transport. The DP model described the bromide elution curves of the sieved soil columns well, whereas it overestimated the tailing of the bromide BTCs of the undisturbed soil columns. A higher degree of physical non-equilibrium was found in the undisturbed soil, where 56% of total water was contained in the slow-flow matrix, compared to 26% in the sieved soil. Isoproturon BTCs were best described in both sieved and undisturbed soil columns using the DP model combined with the chemical non-equilibrium. Higher degradation rates were obtained in the transport experiments than in batch studies, for both soils. This was likely caused by hysteresis in sorption of isoproturon. However, it cannot be ruled out that higher degradation rates were due, at least in part, to the adopted first-order model. Results showed that for similar rainfall intensity, physical and chemical non-equilibrium were greater in the saturated undisturbed soil than in the unsaturated sieved soil. Results also suggested faster transport of isoproturon in the undisturbed soil due to higher preferential flow and lower fraction of equilibrium sorption sites.

Evaluating equilibrium and non-equilibrium transport of bromide and isoproturon in disturbed and undisturbed soil columns

NASA Astrophysics Data System (ADS)

Dousset, S.; Thevenot, M.; Pot, V.; Šimunek, J.; Andreux, F.

2007-12-01

In this study, displacement experiments of isoproturon were conducted in disturbed and undisturbed columns of a silty clay loam soil under similar rainfall intensities. Solute transport occurred under saturated conditions in the undisturbed soil and under unsaturated conditions in the sieved soil because of a greater bulk density of the compacted undisturbed soil compared to the sieved soil. The objective of this work was to determine transport characteristics of isoproturon relative to bromide tracer. Triplicate column experiments were performed with sieved (structure partially destroyed to simulate conventional tillage) and undisturbed (structure preserved) soils. Bromide experimental breakthrough curves were analyzed using convective-dispersive and dual-permeability (DP) models (HYDRUS-1D). Isoproturon breakthrough curves (BTCs) were analyzed using the DP model that considered either chemical equilibrium or non-equilibrium transport. The DP model described the bromide elution curves of the sieved soil columns well, whereas it overestimated the tailing of the bromide BTCs of the undisturbed soil columns. A higher degree of physical non-equilibrium was found in the undisturbed soil, where 56% of total water was contained in the slow-flow matrix, compared to 26% in the sieved soil. Isoproturon BTCs were best described in both sieved and undisturbed soil columns using the DP model combined with the chemical non-equilibrium. Higher degradation rates were obtained in the transport experiments than in batch studies, for both soils. This was likely caused by hysteresis in sorption of isoproturon. However, it cannot be ruled out that higher degradation rates were due, at least in part, to the adopted first-order model. Results showed that for similar rainfall intensity, physical and chemical non-equilibrium were greater in the saturated undisturbed soil than in the unsaturated sieved soil. Results also suggested faster transport of isoproturon in the undisturbed soil due to higher preferential flow and lower fraction of equilibrium sorption sites.

Relevance of anisotropy and spatial variability of gas diffusivity for soil-gas transport

NASA Astrophysics Data System (ADS)

Schack-Kirchner, Helmer; Kühne, Anke; Lang, Friederike

2017-04-01

Models of soil gas transport generally do not consider neither direction dependence of gas diffusivity, nor its small-scale variability. However, in a recent study, we could provide evidence for anisotropy favouring vertical gas diffusion in natural soils. We hypothesize that gas transport models based on gas diffusion data measured with soil rings are strongly influenced by both, anisotropy and spatial variability and the use of averaged diffusivities could be misleading. To test this we used a 2-dimensional model of soil gas transport to under compacted wheel tracks to model the soil-air oxygen distribution in the soil. The model was parametrized with data obtained from soil-ring measurements with its central tendency and variability. The model includes vertical parameter variability as well as variation perpendicular to the elongated wheel track. Different parametrization types have been tested: [i)]Averaged values for wheel track and undisturbed. em [ii)]Random distribution of soil cells with normally distributed variability within the strata. em [iii)]Random distributed soil cells with uniformly distributed variability within the strata. All three types of small-scale variability has been tested for [j)] isotropic gas diffusivity and em [jj)]reduced horizontal gas diffusivity (constant factor), yielding in total six models. As expected the different parametrizations had an important influence to the aeration state under wheel tracks with the strongest oxygen depletion in case of uniformly distributed variability and anisotropy towards higher vertical diffusivity. The simple simulation approach clearly showed the relevance of anisotropy and spatial variability in case of identical central tendency measures of gas diffusivity. However, until now it did not consider spatial dependency of variability, that could even aggravate effects. To consider anisotropy and spatial variability in gas transport models we recommend a) to measure soil-gas transport parameters spatially explicit including different directions and b) to use random-field stochastic models to assess the possible effects for gas-exchange models.

Succession of Bacterial Community Structure and Diversity in Soil along a Chronosequence of Reclamation and Re-Vegetation on Coal Mine Spoils in China

PubMed Central

Li, Yuanyuan; Wen, Hongyu; Chen, Longqian; Yin, Tingting

2014-01-01

The growing concern about the effectiveness of reclamation strategies has motivated the evaluation of soil properties following reclamation. Recovery of belowground microbial community is important for reclamation success, however, the response of soil bacterial communities to reclamation has not been well understood. In this study, PCR-based 454 pyrosequencing was applied to compare bacterial communities in undisturbed soils with those in reclaimed soils using chronosequences ranging in time following reclamation from 1 to 20 year. Bacteria from the Proteobacteria, Chloroflexi, Actinobacteria, Acidobacteria, Planctomycetes and Bacteroidetes were abundant in all soils, while the composition of predominant phyla differed greatly across all sites. Long-term reclamation strongly affected microbial community structure and diversity. Initial effects of reclamation resulted in significant declines in bacterial diversity indices in younger reclaimed sites (1, 8-year-old) compared to the undisturbed site. However, bacterial diversity indices tended to be higher in older reclaimed sites (15, 20-year-old) as recovery time increased, and were more similar to predisturbance levels nearly 20 years after reclamation. Bacterial communities are highly responsive to soil physicochemical properties (pH, soil organic matter, Total N and P), in terms of both their diversity and community composition. Our results suggest that the response of soil microorganisms to reclamation is likely governed by soil characteristics and, indirectly, by the effects of vegetation restoration. Mixture sowing of gramineae and leguminosae herbage largely promoted soil geochemical conditions and bacterial diversity that recovered to those of undisturbed soil, representing an adequate solution for soil remediation and sustainable utilization for agriculture. These results confirm the positive impacts of reclamation and vegetation restoration on soil microbial diversity and suggest that the most important phase of microbial community recovery occurs between 15 and 20 years after reclamation. PMID:25502754

Biological properties of disturbed and undisturbed Cerrado sensu stricto from Northeast Brazil.

PubMed

Araújo, A S F; Magalhaes, L B; Santos, V M; Nunes, L A P L; Dias, C T S

2017-03-01

The aim of this study was to measure soil microbial biomass and soil surface fauna in undisturbed and disturbed Cerrado sensu stricto (Css) from Sete Cidades National Park, Northeast Brazil. The following sites were sampled under Cerrado sensu stricto (Css) at the park: undisturbed and disturbed Css (slash-and-burn agricultural practices). Total organic and microbial biomass C were higher in undisturbed than in disturbed sites in both seasons. However, microbial biomass C was higher in the wet than in the dry season. Soil respiration did not vary among sites but was higher in the wet than in the dry season. The densities of Araneae, Coleoptera, and Orthoptera were higher in the undisturbed site, whereas the densities of Formicidae were higher in the disturbed site. Non-metric multidimensional scaling analysis separated undisturbed from disturbed sites according to soil biological properties. Disturbance by agricultural practices, such as slash-and-burn, probably resulted in the deterioration of the biological properties of soil under native Cerrado sensu stricto in the Sete Cidades National Park.

Cenozoic stratigraphy of the Sahara, Northern Africa

USGS Publications Warehouse

Swezey, Christopher S.

2009-01-01

This paper presents an overview of the Cenozoic stratigraphic record in the Sahara, and shows that the strata display some remarkably similar characteristics across much of the region. In fact, some lithologies of certain ages are exceptionally widespread and persistent, and many of the changes from one lithology to another appear to have been relatively synchronous across the Sahara. The general stratigraphic succession is that of a transition from early Cenozoic carbonate strata to late Cenozoic siliciclastic strata. This transition in lithology coincides with a long-term eustatic fall in sea level since the middle Cretaceous and with a global climate transition from a Late Cretaceous–Early Eocene “warm mode” to a Late Eocene–Quaternary “cool mode”. Much of the shorter-term stratigraphic variability in the Sahara (and even the regional unconformities) also can be correlated with specific changes in sea level, climate, and tectonic activity during the Cenozoic. Specifically, Paleocene and Eocene carbonate strata and phosphate are suggestive of a warm and humid climate, whereas latest Eocene evaporitic strata (and an end-Eocene regional unconformity) are correlated with a eustatic fall in sea level, the build-up of ice in Antarctica, and the appearance of relatively arid climates in the Sahara. The absence of Oligocene strata throughout much of the Sahara is attributed to the effects of generally low eustatic sea level during the Oligocene and tectonic uplift in certain areas during the Late Eocene and Oligocene. Miocene sandstone and conglomerate are attributed to the effects of continued tectonic uplift around the Sahara, generally low eustatic sea level, and enough rainfall to support the development of extensive fluvial systems. Middle–Upper Miocene carbonate strata accumulated in northern Libya in response to a eustatic rise in sea level, whereas Upper Miocene mudstone accumulated along the south side of the Atlas Mountains because uplift of the mountains blocked fluvial access to the Mediterranean Sea. Uppermost Miocene evaporites (and an end-Miocene regional unconformity) in the northern Sahara are correlated with the Messinian desiccation of the Mediterranean Sea. Abundant and widespread Pliocene paleosols are attributed to the onset of relatively arid climate conditions and (or) greater variability of climate conditions, and the appearance of persistent and widespread eolian sediments in the Sahara is coincident with the major glaciation in the northern hemisphere during the Pliocene.

Observation Versus Embolization in Patients with Blunt Splenic Injury After Trauma: A Propensity Score Analysis.

PubMed

Olthof, Dominique C; Joosse, Pieter; Bossuyt, Patrick M M; de Rooij, Philippe P; Leenen, Loek P H; Wendt, Klaus W; Bloemers, Frank W; Goslings, J Carel

2016-05-01

Non-operative management (NOM) is the standard of care in hemodynamically stable patients with blunt splenic injury after trauma. Splenic artery embolization (SAE) is reported to increase observation success rate. Studies demonstrating improved splenic salvage rates with SAE primarily compared SAE with historical controls. The aim of this study was to investigate whether SAE improves success rate compared to observation alone in contemporaneous patients with blunt splenic injury. We included adult patients with blunt splenic injury admitted to five Level 1 Trauma Centers between January 2009 and December 2012 and selected for NOM. Successful treatment was defined as splenic salvage and no splenic re-intervention. We calculated propensity scores, expressing the probability of undergoing SAE, using multivariable logistic regression and created five strata based on the quintiles of the propensity score distribution. A weighted relative risk (RR) was calculated across strata to express the chances of success with SAE. Two hundred and six patients were included in the study. Treatment was successful in 180 patients: 134/146 (92 %) patients treated with observation and 48/57 (84 %) patients treated with SAE. The weighted RR for success with SAE was 1.17 (0.94-1.45); for complications, the weighted RR was 0.71 (0.41-1.22). The mean number of transfused blood products was 4.4 (SD 9.9) in the observation group versus 9.1 (SD 17.2) in the SAE group. After correction for confounders with propensity score stratification technique, there was no significant difference between embolization and observation alone with regard to successful treatment in patients with blunt splenic injury after trauma.

Realism on the rocks: Novel success and James Hutton's theory of the earth.

PubMed

Rossetter, Thomas

2018-02-01

In this paper, I introduce a new historical case study into the scientific realism debate. During the late-eighteenth century, the Scottish natural philosopher James Hutton made two important successful novel predictions. The first concerned granitic veins intruding from granite masses into strata. The second concerned what geologists now term "angular unconformities": older sections of strata overlain by younger sections, the two resting at different angles, the former typically more inclined than the latter. These predictions, I argue, are potentially problematic for selective scientific realism in that constituents of Hutton's theory that would not be considered even approximately true today played various roles in generating them. The aim here is not to provide a full philosophical analysis but to introduce the case into the debate by detailing the history and showing why, at least prima facie, it presents a problem for selective realism. First, I explicate Hutton's theory. I then give an account of Hutton's predictions and their confirmations. Next, I explain why these predictions are relevant to the realism debate. Finally, I consider which constituents of Hutton's theory are, according to current beliefs, true (or approximately true), which are not (even approximately) true, and which were responsible for these successes. Copyright © 2017 The Author. Published by Elsevier Ltd.. All rights reserved.

Natural forest expansion on reclaimed coal mines in Northern Spain: the role of native shrubs as suitable microsites.

PubMed

Alday, Josu G; Zaldívar, Pilar; Torroba-Balmori, Paloma; Fernández-Santos, Belén; Martínez-Ruiz, Carolina

2016-07-01

The characterization of suitable microsites for tree seedling establishment and growth is one of the most important tasks to achieve the restoration of native forest using natural processes in disturbed sites. For that, we assessed the natural Quercus petraea forest expansion in a 20-year-old reclaimed open-cast mine under sub-Mediterranean climate in northern Spain, monitoring seedling survival, growth, and recruitment during 5 years in three contrasting environments (undisturbed forest, mine edge, and mine center). Seedling density and proportion of dead branches decreased greatly from undisturbed forest towards the center of the mine. There was a positive effect of shrubs on Q. petraea seedling establishment in both mine environments, which increase as the environment undergoes more stress (from the mine edge to the center of the mine), and it was produced by different shrub structural features in each mine environment. Seedling survival reduction through time in three environments did not lead to a density reduction because there was a yearly recruitment of new seedlings. Seedling survival, annual growth, and height through time were greater in mine sites than in the undisturbed forest. The successful colonization patterns and positive neighbor effect of shrubs on natural seedlings establishment found in this study during the first years support the use of shrubs as ecosystem engineers to increase heterogeneity in micro-environmental conditions on reclaimed mine sites, which improves late-successional Quercus species establishment.

Understanding staff perceptions about Klebsiella pneumoniae carbapenemase-producing Enterobacteriaceae control efforts in Chicago long-term acute care hospitals.

PubMed

Lyles, Rosie D; Moore, Nicholas M; Weiner, Shayna B; Sikka, Monica; Lin, Michael Y; Weinstein, Robert A; Hayden, Mary K; Sinkowitz-Cochran, Ronda L

2014-04-01

To identify differences in organizational culture and better understand motivators to implementation of a bundle intervention to control Klebsiella pneumoniae carbapenemase-producing Enterobacteriaceae (KPC). Mixed-methods study. Four long-term acute care hospitals (LTACHs) in Chicago. LTACH staff across 3 strata of employees (administration, midlevel management, and frontline clinical workers). Qualitative interviews or focus groups and completion of a quantitative questionnaire. Eighty employees (frontline, 72.5%; midlevel, 17.5%; administration, 10%) completed surveys and participated in qualitative discussions in August 2012. Although 82.3% of respondents felt that quality improvement was a priority at their LTACH, there were statistically significant differences in organizational culture between staff strata, with administrative-level having higher organizational culture scores (ie, more favorable responses) than midlevel or frontline staff. When asked to rank the success of the KPC control program, mean response was 8.0 (95% confidence interval, 7.6-8.5), indicating a high level of agreement with the perception that the program was a success. Patient safety and personal safety were reported most often as personal motivators for intervention adherence. The most convergent theme related to prevention across groups was that proper hand hygiene is vital to prevention of KPC transmission. Despite differences in organizational culture across 3 strata of LTACH employees, the high degree of convergence in motivation, understanding, and beliefs related to implementation of a KPC control bundle suggests that all levels of staff may be able to align perspectives when faced with a key infection control problem and quality improvement initiative.

Photoacoustic FTIR spectroscopic study of undisturbed nacre from red abalone

NASA Astrophysics Data System (ADS)

Verma, Devendra; Katti, Kalpana; Katti, Dinesh

2006-07-01

In this work, photoacoustic Fourier transform infrared (PA-FTIR) spectroscopy has been utilized to study interfacial interactions of undisturbed nacre and nacre powder from red abalone shell. The spectra of both undisturbed nacre and nacre powder showed characteristic bands of aragonite and proteins. Although nacre powder and undisturbed nacre are chemically identical, PA-FTIR spectrum of undisturbed nacre is found to be significantly different from that of nacre powder. A broad and strong band is observed at around 1485 cm -1 in nacre powder. The intensity of this band is notably reduced in undisturbed nacre. This result is explained on the basis of interfacial interactions between aragonite platelets and acidic proteins. It is also observed that band at around 1788 cm -1 originates from three overlapping bands 1797, 1787 and 1778 cm -1. The band at around 1787 cm -1 is assigned to C dbnd O stretching of carboxylate groups of acidic proteins. The other two bands at 1797 and 1778 cm -1, originate from aragonite and have been assigned to combination bands, ν 3 + ν 4a and ν 3 + ν 4b, respectively. For the study of stratification in undisturbed nacre, PA-FTIR spectra have been collected in step scan mode. The variation in spectra with depth can be attributed to changes in conformation of proteins as well as interfacial interactions.

Effect of wind turbine wakes on summer-time wind profiles in the US Great Plains

NASA Astrophysics Data System (ADS)

Rhodes, M. E.; Lundquist, J. K.; Aitken, M.

2011-12-01

Wind energy is steadily becoming a significant source of grid electricity in the United States, and the Midwestern United States provides one of the nation's richest wind resources. This study examines the effect of wind turbine wakes on the wind profile in central Iowa. Data were collected using a coherent Doppler LiDAR system located approximately 2.5 rotor diameters north of a row of modern multi-MW wind turbine generators. The prevailing wind direction was from the South allowing the LiDAR to capture wind turbine wake properties; however, a number of periods existed where the LiDAR captured undisturbed flow. The LiDAR system reliably obtained readings up to 200 m above ground level (AGL), spanning the entire rotor disk (~40 m to 120 m AGL) which far surpasses the information provided by traditional wind resource assessment instrumentation. We extract several relevant parameters from the lidar data including: horizontal wind speed, vertical velocity, horizontal turbulence intensity, wind shear, and turbulent kinetic energy (TKE). Each time period at a particular LiDAR measurement height was labeled "wake" or "undisturbed" based on the wind direction at that height. Wake and undisturbed data were averaged separately to create a time-height cross-section averaged day for each parameter. Significant differences between wake and undisturbed data emerge. During the day, wake conditions experience larger values of TKE within the altitudes of the turbine rotor disk while TKE values above the rotor disk are similar between waked and undisturbed conditions. Furthermore, the morning transition of TKE in the atmospheric boundary layer commences earlier during wake conditions than in undisturbed conditions, and the evening decay of TKE persists longer during wake conditions. Waked wind shear is consistently greater than undisturbed periods at the edges of the wind turbine rotor disk (40m & 120m AGL), but especially so during the night where wind shear values during wake conditions are three times larger than in undisturbed conditions. Waked conditions show an increased rate of nocturnal subsidence over that of undisturbed conditions, likely due to the momentum deficit as a result of energy extraction by the turbine. Turbulent intensity shows increased levels and longevity in the waked rotor region when compared to the undisturbed conditions. The presentation will present these differences between waked and undisturbed conditions, and compare these observations to the phenomena accounted for in traditional wind turbine wake models.

Multifractal Analysis of Seismically Induced Soft-Sediment Deformation Structures Imaged by X-Ray Computed Tomography

NASA Astrophysics Data System (ADS)

Nakashima, Yoshito; Komatsubara, Junko

Unconsolidated soft sediments deform and mix complexly by seismically induced fluidization. Such geological soft-sediment deformation structures (SSDSs) recorded in boring cores were imaged by X-ray computed tomography (CT), which enables visualization of the inhomogeneous spatial distribution of iron-bearing mineral grains as strong X-ray absorbers in the deformed strata. Multifractal analysis was applied to the two-dimensional (2D) CT images with various degrees of deformation and mixing. The results show that the distribution of the iron-bearing mineral grains is multifractal for less deformed/mixed strata and almost monofractal for fully mixed (i.e. almost homogenized) strata. Computer simulations of deformation of real and synthetic digital images were performed using the egg-beater flow model. The simulations successfully reproduced the transformation from the multifractal spectra into almost monofractal spectra (i.e. almost convergence on a single point) with an increase in deformation/mixing intensity. The present study demonstrates that multifractal analysis coupled with X-ray CT and the mixing flow model is useful to quantify the complexity of seismically induced SSDSs, standing as a novel method for the evaluation of cores for seismic risk assessment.

Geospatial Database for Strata Objects Based on Land Administration Domain Model (ladm)

NASA Astrophysics Data System (ADS)

Nasorudin, N. N.; Hassan, M. I.; Zulkifli, N. A.; Rahman, A. Abdul

2016-09-01

Recently in our country, the construction of buildings become more complex and it seems that strata objects database becomes more important in registering the real world as people now own and use multilevel of spaces. Furthermore, strata title was increasingly important and need to be well-managed. LADM is a standard model for land administration and it allows integrated 2D and 3D representation of spatial units. LADM also known as ISO 19152. The aim of this paper is to develop a strata objects database using LADM. This paper discusses the current 2D geospatial database and needs for 3D geospatial database in future. This paper also attempts to develop a strata objects database using a standard data model (LADM) and to analyze the developed strata objects database using LADM data model. The current cadastre system in Malaysia includes the strata title is discussed in this paper. The problems in the 2D geospatial database were listed and the needs for 3D geospatial database in future also is discussed. The processes to design a strata objects database are conceptual, logical and physical database design. The strata objects database will allow us to find the information on both non-spatial and spatial strata title information thus shows the location of the strata unit. This development of strata objects database may help to handle the strata title and information.

Exploring an analytic model of urban housing strata.

PubMed

Park, J H

1992-07-01

An analytic model of urban housing strata is developed which utilizes housing structure type, housing tenure type, floor size, physical quality, residential area, and number of rooms to calculate a housing deficit for each housing characteristic. The housing norm is subtracted from the actual housing conditions. Each housing deficit value is weighted according to the priority of the 6 variables and then summed as the housing strata score. Negative scores are below the norm and positive ones above. The model is applied to empirical data for Seoul, Korea. The findings were that 66% of the family sample showed negative scores (unsatisfactory housing conditions). Scores range from -22 to =or+ 18. Morris and Winter's "housing adjustment model" is used to explain housing behavior when there is a gap between housing conditions and the norm. Housing behavior is analyzed with multiple regression analysis of housing strata, social strata, and family life stage variables. Findings indicate that the establishment stage in the family life cycle is more likely to be associated with upper housing strata. From the way the model is set up only those in the establishment, childbearing, and child-rearing stage could get a positive deficit housing score. Size of household is not statistically significant, but upper housing strata are reflective of families with 2.5 members. Those with 3-4.5 members may be in the upper middle housing strata. Those with 5 children are in the lower middle housing strata. Housing strata are significantly related to housing structure type, tenure type, and size and number of rooms. The high rise apartment is likely to be in the upper, the row house and multifamily house in the lower housing, and the single detached house is distributed through all 4 strata. Home ownership is highest in the upper strata. The proportion of housing with 18 pyong and 2 rooms is higher in the lower strata, while housing with 19-32 pyong (63-106 sq. ms) and 3 rooms is higher in the middle housing strata. Housing satisfaction is significantly explained by housing strata but not general social strata (r = .13). Propensity to move is explained by family life stage followed by housing strata.

Late Laramide thrust-related and evaporite-domed anticlines in the southern Piceance Basin, northeastern Colorado Plateau

USGS Publications Warehouse

Grout, M.A.; Abrams, G.A.; Tang, R.L.; Hainsworth, T.J.; Verbeek, E.R.

1991-01-01

New seismic and gravity data across the hydrocarbon-producing Divide Creek and Wolf Creek anticlines in the southern Piceance basin reveal contrasting styles of deformation within two widely separated time frames. Seismic data indicate that prebasin Paleozoic deformation resulted in block faulting of the Precambrian crystalline basement rocks and overlying Cambrian through Middle Pennsylvanian strata. Movement along these block faults throughout much of Pennsylvanian time, during northeast-southwest crustal extension, likely influenced distribution of the Middle Pennsylvanian (Desmoinesian) evaporite-rich facies. Younger rocks, including the thick succession of Cenozoic basin strata, then buried the Paleozoic structures. Gravity data confirm that excess material of relatively low density exists beneath the Wolf Creek structure, whereas material of relatively higher density (overthickened shale) is found beneath the Divide Creek Anticline. -from Authors

[Capacity of response of the health system to the expectations of populations in zones exposed to results-based financing in Benin in 2015].

PubMed

Salami, Lamidhi; Dona Ouendo, Edgard-Marius; Fayomi, Benjamin

2017-07-10

Introduction: The increased use of results-based financing (RBF) services was the basis for this study designed to evaluate the contribution of RBF to the capacity of response of the health system to the population’s expectations. Methods: This study, conducted in six Benin health zones randomly selected in two strata exposed to RBF (FBR_PRPSS and FBR_PASS) and one zone not exposed to RBF (Non_FBR), examined the seven dimensions of reactivity. A score, followed by weighting of their attributes, was used to calculate the index of reactivity (IR). Results: Sixty-seven health care units and 653 people were observed and interviewed. The FBR_PRPSS and FBR_PASS strata, managed by the new provisions of RBF, displayed good performances for the “rapidity of management” (70% and 80%) and “quality of the health care environment” dimensions, with a more marked improvement for the PRPSS model, which provides greater resources. Poor access to social welfare networks in the three strata led to renouncing of health care. The capacity of response to expectations was moderate and similar in the Non_FBR (IR = 0.53), FBR_PASS (IR = 0.62) and FBR_PRPSS (IR = 0.61) strata (p > 0.05). Conclusion: The FBR_PRPSS and FBR_PASS models have a non-significant effect on the capacity of response. Their success probably depends on the health system context, the combination of targeted interventions, such as universal health insurance, but also the importance and the use of the new resources that they provide.

Capture and Three Dimensional Projection of New South Wales Strata Plans in Landxml Format

NASA Astrophysics Data System (ADS)

Harding, B.; Foreman, A.

2017-10-01

New South Wales is embarking on a major reform program named Cadastre NSW. This reform aims to move to a single source of truth for the digital representation of cadastre. The current lack of a single source cadastre has hindered users from government and industry due to duplication of effort and misalignment between databases from different sources. For this reform to be successful, there are some challenges that need to be addressed. "Cadastre 2034 - Powering Land & Real Property" (2015) published by the Intergovernmental Committee on Surveying and Mapping (ICSM) identifies that current cadastres do not represent real property in three dimensions. In future vertical living lifestyles will create complex property scenarios that the Digital Cadastral Database (DCDB) will need to contend with. While the NSW DCDB currently holds over 3 million lots and 5 million features, one of its limitations is that it does not indicate land ownership above or below the ground surface. NSW Spatial Services is currently capturing survey plans into LandXML format. To prepare for the future, research is being undertaken to also capture multi-level Strata Plans through a modified recipe. During this research, multiple Strata Plans representing a range of ages and development types have been investigated and converted to LandXML. Since it is difficult to visualise the plans in a two dimensional format, quality control purposes require a method to display these plans in three dimensions. Overall investigations have provided Spatial Services with enough information to confirm that the capture and display of Strata Plans in the LandXML format is possible.

Thermal Maturity of Pennsylvanian Coals and Coaly Shales, Eastern Shelf and Fort Worth Basin, Texas

USGS Publications Warehouse

Hackley, Paul C.; Guevara, Edgar H.; Hentz, Tucker F.; Hook, Robert W.

2007-01-01

The U.S. Geological Survey and the Texas Bureau of Economic Geology are engaged in an ongoing collaborative study to characterize the organic composition and thermal maturity of Upper Paleozoic coal-bearing strata from the Eastern Shelf of the Midland basin and from the Fort Worth basin, north-central Texas. Data derived from this study will have application to a better understanding of the potential for coalbed gas resources in the region. This is an important effort in that unconventional resources such as coalbed gas are expected to satisfy an increasingly greater component of United States and world natural gas demand in coming decades. In addition, successful coalbed gas production from equivalent strata in the Kerr basin of southern Texas and from equivalent strata elsewhere in the United States suggests that a closer examination of the potential for coalbed gas resources in north-central Texas is warranted. This report presents thermal maturity data for shallow (<2,000 ft; <610 m) coal and coaly shale cuttings, core, and outcrop samples from the Middle-Upper Pennsylvanian Strawn, Canyon, and Cisco Groups from the Eastern Shelf of the Midland basin. Data for Lower Pennsylvanian Atoka Group strata from deeper wells (5,400 ft; 1,645 m) in the western part of the Fort Worth basin also are included herein. The data indicate that the maturity of some Pennsylvanian coal and coaly shale samples is sufficient to support thermogenic coalbed gas generation on the Eastern Shelf and in the western Fort Worth basin.

Geology of the Carnegie museum dinosaur quarry site of Diplodocus carnegii, Sheep Creek, Wyoming

USGS Publications Warehouse

Brezinski, D.K.; Kollar, A.D.

2008-01-01

The holotype of Diplodocus carnegii Hatcher, 1901, consists of a partial skeleton (CM 84) that was recovered, along with a second partial skeleton of the same species (CM 94), from the upper 10 m of the Talking Rock facies of the Brushy Basin Member of the Morrison Formation exposed along Bone Quarry Draw, a tributary of Sheep Creek in Albany County, Wyoming. A composite measured section of the stratigraphic interval exposed adjacent to the quarry indicates that the Brushy Basin Member in this area is a stacked succession of lithofacies consisting of hackly, greenish gray, calcareous mudstone and greenish brown, dense, fine-grained limestone. The more erosion resistant limestone layers can be traced over many hundreds of meters. Thus, these strata do not appear to represent a highly localized deposit such as a stream channel, oxbow lake, or backwater pond. The Sheep Creek succession is interpreted as representing a clastic-dominated lake where high turbidity and sediment influx produced deposition of calcareous mudstone. During drier periods the lake's turbidity decreased and limestone and dolomite precipitation replaced mud deposition. Microkarsting at the top of some limestone/ dolomite layers suggests subaerial deposition may have prevailed during these dry episodes. The quarry of D. carnegii was excavated within the top strata of one of the numerous intervals of hackly, greenish gray, calcareous mudstone that represent an ephemeral freshwater lake. The quarry strata are directly overlain by 0.3 m of dolomite-capped limestone that was deposited shortly after interment of D. carnegii in the lake mudstones. The close vertical proximity of the overlying limestone to the skeleton's stratigraphic: level suggests that the animal's carcass may have been buried beneath the drying lake deposits during a period of decreased rainfall.

Seismic facies and stratigraphy of the Cenozoic succession in McMurdo Sound, Antarctica: Implications for tectonic, climatic and glacial history

USGS Publications Warehouse

Fielding, C.R.; Whittaker, J.; Henrys, S.A.; Wilson, T.J.; Nash, T.R.

2007-01-01

A new stratigraphic model is presented for the evolution of the Cenozoic Victoria Land Basin of the West Antarctic Rift, based on integration of seismic reflection and drilling data. The Early Rift phase (?latest Eocene to Early Oligocene) comprises wedges of strata confined by early extensional faults, and which contain seismic facies consistent with drainage via coarse-grained fans and deltas into discrete, actively subsiding grabens and half-grabens. The Main Rift phase (Early Oligocene to Early Miocene) comprises a lens of strata that thickens symmetrically from the basin margins into a central depocenter, and in which stratal events pass continuously over the top of the Early Rift extensional topography. Internal seismic facies and lithofacies indicate a more organized, cyclical shallow marine succession, influenced increasingly upward by cycles of glacial advance and retreat into the basin. The Passive Thermal Subsidence phase (Early Miocene to ?) comprises an evenly distributed sheet of strata that does not thicken appreciably into the depocentre, with more evidence for clinoform sets and large channels. These patterns are interpreted to record accumulation under similar environmental conditions but in a regime of slower subsidence. The Renewed Rifting phase (? to Recent, largely unsampled by coring thus far) has been further divided into 1, a lower interval, in which the section thickens passively towards a central depocentre, and 2. an upper interval, in which more dramatic thickening patterns are complicated by magmatic activity. The youngest part of the stratigraphy was accumulated under the influence of flexural loading imposed by the construction of large volcanic edifices, and involved minimal sediment supply from the western basin margin, suggesting a change in environmental (glacial) conditions at possibly c. 2 Ma.

High-resolution sequence stratigraphy of lower Paleozoic sheet sandstones in central North America: The role of special conditions of cratonic interiors in development of stratal architecture

USGS Publications Warehouse

Runkel, Anthony C.; Miller, J.F.; McKay, R.M.; Palmer, A.R.; Taylor, John F.

2007-01-01

Well-known difficulties in applying sequence stratigraphic concepts to deposits that accumulated across slowly subsiding cratonic interior regions have limited our ability to interpret the history of continental-scale tectonism, oceanographic dynamics of epeiric seas, and eustasy. We used a multi-disciplinary approach to construct a high-resolution stratigraphic framework for lower Paleozoic strata in the cratonic interior of North America. Within this framework, these strata proved readily amenable to modern sequence stratigraphic techniques that were formulated based on successions along passive margins and in foreland basins, settings markedly different from the cratonic interior. Parasequences, parasequence stacking patterns, systems tracts, maximum flooding intervals, and sequence-bounding unconformities can be confidently recognized in the cratonic interior using mostly standard criteria for identification. The similarity of cratonic interior and foreland basin successions in size, geometry, constituent facies, and local stacking patterns of nearshore parasequences is especially striking. This similarity indicates that the fundamental processes that establish shoreface morphology and determine the stratal expression of retreat and progradation were likewise generally the same, despite marked differences in tectonism, physiography, and bathymetry between the two settings. Our results do not support the widespread perception that Paleozoic cratonic interior successions are so anomalous in stratal geometries, and constitute such a poor record of time, that they are poorly suited for modern sequence stratigraphic analyses. The particular arrangement of stratal elements in the cratonic interior succession we studied is no more anomalous or enigmatic than the variability in architecture that sets all sedimentary successions apart from one another. Thus, Paleozoic strata of the cratonic interior are most appropriately considered as a package that belongs in a continuum of variable stratigraphic packages reflecting variable controls such as subsidence and shelf physiography. Special conditions of exceptionally slow subsidence rate, shallow bathymetry, and nearly flat regional shelf gradient are manifest mostly by the presence of individual systems tracts of relatively long duration that extend for much greater distances across depositional strike than those that characterize successions deposited in more dynamic tectonic and physiographic settings. These results suggest that if other cratonic interior successions are as anomalous as reported, a low sediment supply may have played a primary role in development of their apparently condensed stratal architecture. The results also lead us to suggest that a nonvegetated lower Paleozoic landscape played a relatively insignificant role in the development of what are commonly perceived to be enigmatic stratigraphic features of sheet sandstones, particularly their widespread yet thin geometry, and a scarcity of shale and siltstone. ?? 2007 Geological Society of America.

Valley-fill sequences and onlap geometries, Lower Cretaceous Muddy Sandstone, Kitty Field, Powder River basin, Wyoming

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

Gardner, M.H.; Gustason, E.R.

1987-05-01

The Muddy Sandstone at Kitty field is a valley-fill sequence that records a late Albian sea level rise and accompanying transgression. The valley was cut during a preceding sea level lowstand. Stratal geometries and facies successions within the valley fill demonstrate the history of transgression was not gradual and progressive. Rather, the valley fill comprises a series of discrete, time-bounded, depositional units which onlap the erosional surface. Five time-bounded depositional units were defined by facies successions and were used to define onlap geometries. Facies successions within individual units record progressive shoaling. Capping each succession, there may be a planar disconformity,more » a thin bioturbated interval, or the deepest water facies of the next depositional event. Thus, the termination of each depositional event is marked by an episode of rapid deepening. At a single geographic location, stratal successions within older depositional units represent more landward facies than those within younger units. Therefore, the onlap geometry of the valley-fill sequence consists of a landward-stepping arrangement of depositional units. The primary reservoirs within the valley-fill sequence, at Kitty field, are laterally coalesced, channel-belt sandstones at the base and barrier island sandstones at the top. Reservoir sandstones of lesser quality occur within the intermediate estuarine facies. The stacking pattern, developed by onlap of the units, results in multiple pay zones within mid-valley reaches. The boundaries of each depositional unit define a high-resolution, chronostratigraphic correlation of valley-fill strata, a correlation corroborated by bentonites. This correlation method gives an accurate description of the internal geometry of valley-fill strata and, therefore, provides a basis for understanding the process of transgressive onlap.« less

Short-term dynamics of second-growth mixed mesophytic forest strata in West Virginia

Treesearch

Cynthia C. Huebner; Steven L. Stephenson; Harold S. Adams; Gary W. Miller

2007-01-01

The short-term dynamics of mixed mesophytic forest strata in West Virginia were examined using similarity analysis and linear correlation of shared ordination space. The overstory tree, understory tree, shrub/vine, and herb strata were stable over a six year interval, whereas the tree seedling and sapling strata were unstable. All strata but the shrub/vine and tree...

Disturbance-mediated accelerated succession in two Michigan forest types

USGS Publications Warehouse

Abrams, Marc D.; Scott, Michael L.

1989-01-01

In northern lower Michigan, logging accelerated sugar maple (Acer saccharum) dominance in a northern white cedar (Thuja occidentals) community, and clear-cutting and burning quickly converted certain sites dominated by mature jack pine (Pinus banksiana) to early-succesional hardwoods, including Prunus, Populus, and Quercus. In both forest types the succeeding hardwoods should continue to increase in the future at the expense of the pioneer conifer species. In the cedar example, sugar maple was also increasing a an undisturbed, old-growth stand, but at a much reduced rate than in the logged stand. Traditionally, disturbance was through to set back succession to some earlier stage. However, out study sites and at least several other North American forest communities exhibited accelerated succession following a wide range of disturbances, including logging fire, ice storms, wind-throw, disease, insect attack, and herbicide spraying.

A study of calcium intake and sources of calcium in adolescent boys and girls from two socioeconomic strata, in Pune, India.

PubMed

Sanwalka, Neha J; Khadilkar, Anuradha V; Mughal, M Zulf; Sayyad, Mehmood G; Khadilkar, Vaman V; Shirole, Shilpa C; Divate, Uma P; Bhandari, Dhanshari R

2010-01-01

Adequate intake of calcium is important for skeletal growth. Low calcium intake during childhood and adolescence may lead to decreased bone mass accrual thereby increasing the risk of osteoporotic fractures. Our aim was to study dietary calcium intake and sources of calcium in adolescents from lower and upper economic strata in Pune, India. We hypothesized that children from lower economic strata would have lower intakes of calcium, which would predominantly be derived from non-dairy sources. Two hundred male and female adolescents, from lower and upper economic stratum were studied. Semiquantitative food frequency questionnaire was used to evaluate intakes of calcium, phosphorus, oxalic acid, phytin, energy and protein. The median calcium intake was significantly different in all four groups, with maximum intake in the upper economic strata boys (893 mg, 689-1295) and lowest intake in lower economic strata girls (506 mg, 380-674). The median calcium intake in lower economic strata boys was 767 mg (585-1043) and that in upper economic strata girls was 764 mg (541-959). The main source of calcium was dairy products in upper economic strata adolescents while it was dark green leafy vegetables in lower economic strata adolescents. The median calcium intake was much lower in lower economic strata than in the upper economic strata both in boys and girls. Girls from both groups had less access to dairy products as compared to boys. Measures need to be taken to rectify low calcium intake in lower economic strata adolescents and to address gender inequality in distribution of dairy products in India.

Modeling diffusion and reaction in soils: 9. The Buckingham-Burdine-Campbell equation for gas diffusivity in undisturbed soil

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

Moldrup, P.; Olesen, T.; Yamaguchi, T.

1999-08-01

Accurate description of gas diffusivity (ratio of gas diffusion coefficients in soil and free air, D{sub s}/D{sub 0}) in undisturbed soils is a prerequisite for predicting in situ transport and fate of volatile organic chemicals and greenhouse gases. Reference point gas diffusivities (R{sub p}) in completely dry soil were estimated for 20 undisturbed soils by assuming a power function relation between gas diffusivity and air-filled porosity ({epsilon}). Among the classical gas diffusivity models, the Buckingham (1904) expression, equal to the soil total porosity squared, best described R{sub p}. Inasmuch, as their previous works implied a soil-type dependency of D{sub s}/D{submore » 0}({epsilon}) in undisturbed soils, the Buckingham R{sub p} expression was inserted in two soil-type-dependent D{sub s}/D{sub 0}({epsilon}) models. One D{sub s}/D{sub 0}({epsilon}) model is a function of pore-size distribution (the Campbell water retention parameter used in a modified Burdine capillary tube model), and the other is a calibrated, empirical function of soil texture (silt + sand fraction). Both the Buckingham-Burdine-Campbell (BBC) and the Buckingham/soil texture-based D{sub s}/D{sub 0}({epsilon}) models described well the observed soil type effects on gas diffusivity and gave improved predictions compared with soil type independent models when tested against an independent data set for six undisturbed surface soils. This study emphasizes that simple but soil-type-dependent power function D{sub s}/D{sub 0}({epsilon}) models can adequately describe and predict gas diffusivity in undisturbed soil. The authors recommend the new BBC model as basis for modeling gas transport and reactions in undisturbed soil systems.« less

Mineralogical Changes in a Predominantly Fluviolacustrine Succession at Gale Crater, Mars

NASA Technical Reports Server (NTRS)

Rampe, E. B.; Ming, D. W.; Grotzinger. J. P.; Bristow, T. F.; Blake, D. F.; Vaniman, D. T.; Chipera, S. J.; Gellert, R.; Morris, R. V.; Morrison, S. M.

2017-01-01

The Mars Science Laboratory Curiosity rover landed in Gale crater in August 2012 to investigate the strata of lower Aeolis Mons (i.e., Mount Sharp) and characterize their depositional and diagenetic environments. Visible/short-wave infrared spectra from orbit of these strata show variations in phyllosilicate, sulfate, and Fe-oxide minerals, suggesting these units record environmental changes that occurred during the early Hesperian. Curiosity has traversed over 15 km and has climbed through Approx. 200 m of stratigraphic section, made up of predominantly fluviolacustrine (i.e., the Bradbury group and the Murray formation) and aeolian (i.e., the Stimson formation) units. Multiple geochemical and mineralogical instruments are onboard Curiosity to study these ancient rocks, including the Chemistry and Mineralogy (CheMin) instrument, which is an X-ray diffractometer (XRD) and X-ray fluorescence spectrometer, and the Alpha Particle X-ray Spectrometer (APXS).

A Glimpse at Late Mesozoic to Early Tertiary Offshore Stratigraphy from Wilkes Land, East Antarctica: Results of Strategic Dredging of the Mertz-Ninnis Trough

NASA Astrophysics Data System (ADS)

Schrum, H.; Domack, E.; Desantis, L.; Leventer, A.; McMullen, K.; Escutia, C.

2004-12-01

As early as 1912 Sir Douglas Mawson demonstrated that pre-glacial sedimentary successions could be recovered by seafloor dredging of erosional troughs found offshore, East Antarctica. Since then, little systematic dredging has been undertaken in Antarctica despite indications of outcropping strata exposed along seaward flanks of glacially excavated troughs and the dire need to resolve the nature of preglacial and synglacial strata in this region. During cruise NB Palmer 01-01, three dredges were collected in echelon along the seaward flank of the Mertz-Ninnis Trough, parallel to the Mertz Ice Tongue, in water depths of 900 to 450 m. We combine biostratigraphic (palynologic) and lithologic analyses on sedimentary clasts with multi- and single-channel seismic reflection data collected by the WEGA cruise in 2000. 1359 pebble to cobble sized clasts were collected from three dredges. Of these 15% to 43%, within each dredge, were of sedimentary character, including carbonaceous sandstones with plant macrofossils, black sulfide-rich mudstones, siltstones, lignites, red quartz arenites, arkoses, and diamictites in various states of lithification. Palynomorphs were separated from these sedimentary rocks. We examined eleven individual lithologies, nine of which yielded useful palynological detritus. Of these samples, five yielded palynomorphs distinctive to the Paleogene (i.e. Nothofagus flemingii, Tricolporites spp., Proteacidites spp.); two samples contained only Lower Cretaceous palynomorphs, while three samples provided no stratigraphically useful palynomorph kerogen. We combine these results with multi-channel seismic and multibeam swath mapping to demonstrate that dredged materials represent seafloor outcrop or shallow subcrop of strata beneath a thin glacial till. Our stratigraphic model for these samples is consistent with 62 km of multichannel seismic reflection data (WEGA line W02) showing seaward dipping strata onlapping the basement to the southwest and partly infilling a rifted basin of late Cretaceous age. Seaward dipping reflectors above the syn-rift strata represent post-rift deposits ranging from Paleogene to Quaternary. Included within this stratigraphy are lithified diamictites containing Mesozoic palynomorphs in addition to palynomorphs of Early Tertiary age (including dinoflagellates). Seaward dipping reflectors in the deep axis of the Mertz-Ninnis Trough were not sampled directly by our dredges, but are believed to be Lower Cretaceous siltstones by extrapolation to core DF-79-38, 100 km along strike to the southeast (Domack et al., 1980). Furthermore, the thermal maturity of the lignite samples recovered in our collections suggests that the coal is of Early Tertiary age, as are numerous organic-rich mudstones, which contain Paleogene palynomorphs. These results indicate that sedimentary strata in this portion of the Wilkes Land Margin contain significantly thick (greater than 2.7 km) post-rift (drift phase) marine sequences of both pre- and synglacial character. Strategic dredging is a promising methodology by which to sample stratigraphic succession in a cost effective manner along the East Antarctic margin in the absence of, or preparation for, International Ocean Drilling Projects on the shelf. Domack, E. W., Fairchild, W. W., and Anderson, J. B. (1980) Lower Cretaceous sediment from the East Antarctic continental shelf, Nature, 287, 625-626.

A Russian record of a Middle Ordovician meteorite shower: Extraterrestrial chromite at Lynna River, St. Petersburg region

NASA Astrophysics Data System (ADS)

Lindskog, Anders; Schmitz, Birger; Cronholm, Anders; Dronov, Andrei

2012-08-01

Numerous fossil meteorites and high concentrations of sediment-dispersed extraterrestrial chromite (EC) grains with ordinary chondritic composition have previously been documented from 467 ± 1.6 Ma Middle Ordovician (Darriwilian) strata. These finds probably reflect a temporarily enhanced influx of L-chondritic matter, following the disruption of the L-chondrite parent body in the asteroid belt 470 ± 6 Ma. In this study, a Volkhovian-Kundan limestone/marl succession at Lynna River, northwestern Russia, has been searched for EC grains (>63 μm). Eight samples, forming two separate sample sets, were collected. Five samples from strata around the Asaphus expansus-A. raniceps trilobite Zone boundary, in the lower-middle Kundan, yielded a total of 496 EC grains in 65.5 kg of rock (average 7.6 EC grains kg-1, but up to 10.2 grains kg-1). These are extremely high concentrations, three orders of magnitude higher than "background" levels in similar condensed sediment from other periods. EC grains are typically about 50 times more abundant than terrestrial chrome spinel in the samples and about as common as terrestrial ilmenite. Three stratigraphically lower lying samples, close to the A. lepidurus-A. expansus trilobite Zone boundary, at the Volkhov-Kunda boundary, yielded only two EC grains in 38.2 kg of rock (0.05 grains kg-1). The lack of commonly occurring EC grains in the lower interval probably reflects that these strata formed before the disruption of the L-chondrite parent body. The great similarity in EC chemical composition between this and other comparable studies indicates that all or most EC grains in these Russian mid-Ordovician strata share a common source--the L-chondrite parent body.

Geologic framework for the national assessment of carbon dioxide storage resources: Powder River Basin, Wyoming, Montana, South Dakota, and Nebraska: Chapter B in Geologic framework for the national assessment of carbon dioxide storage resources

USGS Publications Warehouse

Craddock, William H.; Drake II, Ronald M.; Mars, John L.; Merrill, Matthew D.; Warwick, Peter D.; Blondes, Madalyn S.; Gosai, Mayur A.; Freeman, P.A.; Cahan, Steven A.; DeVera, Christina A.; Lohr, Celeste D.; Warwick, Peter D.; Corum, Margo D.

2012-01-01

This report presents ten storage assessment units (SAUs) within the Powder River Basin of Wyoming, Montana, South Dakota, and Nebraska. The Powder River Basin contains a thick succession of sedimentary rocks that accumulated steadily throughout much of the Phanerozoic, and at least three stratigraphic packages contain strata that are suitable for CO2 storage. Pennsylvanian through Triassic siliciclastic strata contain two potential storage units: the Pennsylvanian and Permian Tensleep Sandstone and Minnelusa Formation, and the Triassic Crow Mountain Sandstone. Jurassic siliciclastic strata contain one potential storage unit: the lower part of the Sundance Formation. Cretaceous siliciclastic strata contain seven potential storage units: (1) the Fall River and Lakota Formations, (2) the Muddy Sandstone, (3) the Frontier Sandstone and Turner Sandy Member of the Carlile Shale, (4) the Sussex and Shannon Sandstone Members of Cody Shale, and (5) the Parkman, (6) Teapot, and (7) Teckla Sandstone Members of the Mesaverde Formation. For each SAU, we discuss the areal distribution of suitable CO2 reservoir rock. We also characterize the overlying sealing unit and describe the geologic characteristics that influence the potential CO2 storage volume and reservoir performance. These characteristics include reservoir depth, gross thickness, net thickness, porosity, permeability, and groundwater salinity. Case-by-case strategies for estimating the pore volume existing within structurally and (or) stratigraphically closed traps are presented. Although assessment results are not contained in this report, the geologic information included herein will be employed to calculate the potential storage space in the various SAUs.

Study on the Rule of Super Strata Movement and Subsidence

NASA Astrophysics Data System (ADS)

Yao, Shunli; Yuan, Hongyong; Jiang, Fuxing; Chen, Tao; Wu, Peng

2018-01-01

The movement of key strata is related to the safety of the whole earth’s surface for coal mining under super strata. Based on the key strata theory, the paper comprehensively analyzes the characteristics of the subsidence before and after the instability of the super strata by studing through FLAC3D and microseismic dynamic monitoring of the surface rock movement observation. The stability of the super strata movement is analyzed according to the characteristic value of the subsidence. The subsidence law and quantitative indexes under the control of the super rock strata that provides basis for the prevention and control of surface risk, optimize mining area and face layout and reasonably set mining boundary around mining area. It provides basis for the even growth of mine safety production and regional public safety.

Eocene lake basins in Wyoming and Nevada record rollback of the Farallon flat-slab beneath western North America

NASA Astrophysics Data System (ADS)

Smith, M. E.; Cassel, E. J.; Jicha, B. R.; Singer, B. S.; Carroll, A.

2014-12-01

Numerical and conceptual models of flat-slab rollback predict broad initial dynamic subsidence above the slab hinge then uplift and volcanism triggered by the advection of asthenosphere beneath the overriding plate. These predicted surface effects provide a viable but largely untested explanation for lake basin formation in Cordilleran-type orogenies. We argue that the hydrologic closure of both the foreland (early Eocene) and hinterland (late Eocene) of the North American Cordillera were caused by a trenchward-migrating wave of dynamic and thermal topography resulting from progressive removal of the Farallon flat-slab. Two major episodes of hydrologic drainage closure are recorded by Eocene terrestrial strata in the western United States. The first occurred in the retroarc foreland during the early Eocene, and resulted in the deposition of the Green River Fm. The second occurred in the hinterland during the late Eocene and resulted in accumulation of the Elko Fm. In both regions, lake strata overlie fluvial strata and become progressively more evaporative up-section, and are overlain by volcaniclastic strata. Both successions were then truncated by regional unconformities that extend until the Oligocene. We interpret these stratigraphic successions to record trenchward propagation of a regional topographic wave, caused by slab rollback. Migration of the slab-hinge initially caused dynamic subsidence and initiation of lacustrine deposition. Regional surface uplift followed, and was associated with scattered volcanism. Uplift promoted formation of endorheic basins and ultimately the development of regional unconformities. The height of the uplift can be roughly approximated by the preserved thickness of lacustrine and other nonmarine deposits at both locations (0.2-1.0 km). The 40Ar/39Ar and U-Pb geochronology of Green River Fm ash beds indicate that this surface topographic wave migrated trenchward (SW) across the foreland from 53 to 47 Ma at a velocity of ~6 cm/yr. Single crystal sanidine 40Ar/39Ar ages for ash beds within the Elko Fm indicate hydrologic ponding from 43 to 38 Ma. The 4 myr gap between Green River and Elko Fm deposition may represent the time required for the rollback wave to transit the steep eastern slope of the Sevier fold-thrust belt.

Electrokinetic Enhanced Permanganate Delivery for Low Permeability Soil Remediation

NASA Astrophysics Data System (ADS)

Chowdhury, A. I.; Gerhard, J.; Reynolds, D. A.; Sleep, B. E.; O'Carroll, D. M.

2016-12-01

Contaminant mass sequestered in low permeability zones (LPZ) in the subsurface has become a significant concern due to back diffusion of contaminants, leading to contaminant rebound following treatment of the high permeability strata. In-situ remediation technologies such as in-situ chemical oxidation (ISCO) are promising, however, successful delivery of oxidants into silts and clays remains a challenge. Electrokinetics (EK) has been proposed as a technique that can overcome this challenge by delivering oxidants into low permeability soils. This study demonstrates the ability of EK to facilitate permanganate delivery into silt for treatment of trichloroethene (TCE). A two-dimensional sandbox was packed with alternate vertical layers of coarse sand and silt contaminated with high concentrations of aqueous phase TCE. Nine experiments were conducted to compare EK-enhanced in-situ chemical oxidation (EK-ISCO) to ISCO alone or EK alone. Frequent groundwater sampling at multiple locations combined with image analysis provided detailed mapping of TCE, permanganate, and manganese dioxide mass distributions. EK-ISCO successfully delivered the permanganate throughout the silt cross-section while ISCO without EK resulted in permanganate delivery only to the edges of the silt layer. EK-ISCO resulted in a 4.4 order-of-magnitude (OoM) reduction in TCE concentrations in the coarse sand compared to a 3.5 OoM reduction for ISCO alone. This study suggests that electrokinetics coupled with ISCO can achieve enhanced remediation of lower permeability strata, where remediation technologies for successful contaminant mass removal would otherwise be limited.

High-resolution delineation of chlorinated volatile organic compounds in a dipping, fractured mudstone: Depth- and strata-dependent spatial variability from rock-core sampling

NASA Astrophysics Data System (ADS)

Goode, Daniel J.; Imbrigiotta, Thomas E.; Lacombe, Pierre J.

2014-12-01

Synthesis of rock-core sampling and chlorinated volatile organic compound (CVOC) analysis at five coreholes, with hydraulic and water-quality monitoring and a detailed hydrogeologic framework, was used to characterize the fine-scale distribution of CVOCs in dipping, fractured mudstones of the Lockatong Formation of Triassic age, of the Newark Basin in West Trenton, New Jersey. From these results, a refined conceptual model for more than 55 years of migration of CVOCs and depth- and strata-dependent rock-matrix contamination was developed. Industrial use of trichloroethene (TCE) at the former Naval Air Warfare Center (NAWC) from 1953 to 1995 resulted in dense non-aqueous phase liquid (DNAPL) TCE and dissolved TCE and related breakdown products, including other CVOCs, in underlying mudstones. Shallow highly weathered and fractured strata overlie unweathered, gently dipping, fractured strata that become progressively less fractured with depth. The unweathered lithology includes black highly fractured (fissile) carbon-rich strata, gray mildly fractured thinly layered (laminated) strata, and light-gray weakly fractured massive strata. CVOC concentrations in water samples pumped from the shallow weathered and highly fractured strata remain elevated near residual DNAPL TCE, but dilution by uncontaminated recharge, and other natural and engineered attenuation processes, have substantially reduced concentrations along flow paths removed from sources and residual DNAPL. CVOCs also were detected in most rock-core samples in source areas in shallow wells. In many locations, lower aqueous concentrations, compared to rock core concentrations, suggest that CVOCs are presently back-diffusing from the rock matrix. Below the weathered and highly fractured strata, and to depths of at least 50 meters (m), groundwater flow and contaminant transport is primarily in bedding-plane-oriented fractures in thin fissile high-carbon strata, and in fractured, laminated strata of the gently dipping mudstones. Despite more than 18 years of pump and treat (P&T) remediation, and natural attenuation processes, CVOC concentrations in aqueous samples pumped from these deeper strata remain elevated in isolated intervals. DNAPL was detected in one borehole during coring at a depth of 27 m. In contrast to core samples from the weathered zone, concentrations in core samples from deeper unweathered and unfractured strata are typically below detection. However, high CVOC concentrations were found in isolated samples from fissile black carbon-rich strata and fractured gray laminated strata. Aqueous-phase concentrations were correspondingly high in samples pumped from these strata via short-interval wells or packer-isolated zones in long boreholes. A refined conceptual site model considers that prior to P&T remediation groundwater flow was primarily subhorizontal in the higher-permeability near surface strata, and the bulk of contaminant mass was shallow. CVOCs diffused into these fractured and weathered mudstones. DNAPL and high concentrations of CVOCs migrated slowly down in deeper unweathered strata, primarily along isolated dipping bedding-plane fractures. After P&T began in 1995, using wells open to both shallow and deep strata, downward transport of dissolved CVOCs accelerated. Diffusion of TCE and other CVOCs from deeper fractures penetrated only a few centimeters into the unweathered rock matrix, likely due to sorption of CVOCs on rock organic carbon. Remediation in the deep, unweathered strata may benefit from the relatively limited migration of CVOCs into the rock matrix. Synthesis of rock core sampling from closely spaced boreholes with geophysical logging and hydraulic testing improves understanding of the controls on CVOC delineation and informs remediation design and monitoring.

High-resolution delineation of chlorinated volatile organic compounds in a dipping, fractured mudstone: depth- and strata-dependent spatial variability from rock-core sampling

USGS Publications Warehouse

Goode, Daniel J.; Imbrigiotta, Thomas E.; Lacombe, Pierre J.

2014-01-01

Synthesis of rock-core sampling and chlorinated volatile organic compound (CVOC) analysis at five coreholes, with hydraulic and water-quality monitoring and a detailed hydrogeologic framework, was used to characterize the fine-scale distribution of CVOCs in dipping, fractured mudstones of the Lockatong Formation of Triassic age, of the Newark Basin in West Trenton, New Jersey. From these results, a refined conceptual model for more than 55 years of migration of CVOCs and depth- and strata-dependent rock-matrix contamination was developed. Industrial use of trichloroethene (TCE) at the former Naval Air Warfare Center (NAWC) from 1953 to 1995 resulted in dense non-aqueous phase liquid (DNAPL) TCE and dissolved TCE and related breakdown products, including other CVOCs, in underlying mudstones. Shallow highly weathered and fractured strata overlie unweathered, gently dipping, fractured strata that become progressively less fractured with depth. The unweathered lithology includes black highly fractured (fissile) carbon-rich strata, gray mildly fractured thinly layered (laminated) strata, and light-gray weakly fractured massive strata. CVOC concentrations in water samples pumped from the shallow weathered and highly fractured strata remain elevated near residual DNAPL TCE, but dilution by uncontaminated recharge, and other natural and engineered attenuation processes, have substantially reduced concentrations along flow paths removed from sources and residual DNAPL. CVOCs also were detected in most rock-core samples in source areas in shallow wells. In many locations, lower aqueous concentrations, compared to rock core concentrations, suggest that CVOCs are presently back-diffusing from the rock matrix. Below the weathered and highly fractured strata, and to depths of at least 50 meters (m), groundwater flow and contaminant transport is primarily in bedding-plane-oriented fractures in thin fissile high-carbon strata, and in fractured, laminated strata of the gently dipping mudstones. Despite more than 18 years of pump and treat (P&T) remediation, and natural attenuation processes, CVOC concentrations in aqueous samples pumped from these deeper strata remain elevated in isolated intervals. DNAPL was detected in one borehole during coring at a depth of 27 m. In contrast to core samples from the weathered zone, concentrations in core samples from deeper unweathered and unfractured strata are typically below detection. However, high CVOC concentrations were found in isolated samples from fissile black carbon-rich strata and fractured gray laminated strata. Aqueous-phase concentrations were correspondingly high in samples pumped from these strata via short-interval wells or packer-isolated zones in long boreholes. A refined conceptual site model considers that prior to P&T remediation groundwater flow was primarily subhorizontal in the higher-permeability near surface strata, and the bulk of contaminant mass was shallow. CVOCs diffused into these fractured and weathered mudstones. DNAPL and high concentrations of CVOCs migrated slowly down in deeper unweathered strata, primarily along isolated dipping bedding-plane fractures. After P&T began in 1995, using wells open to both shallow and deep strata, downward transport of dissolved CVOCs accelerated. Diffusion of TCE and other CVOCs from deeper fractures penetrated only a few centimeters into the unweathered rock matrix, likely due to sorption of CVOCs on rock organic carbon. Remediation in the deep, unweathered strata may benefit from the relatively limited migration of CVOCs into the rock matrix. Synthesis of rock core sampling from closely spaced boreholes with geophysical logging and hydraulic testing improves understanding of the controls on CVOC delineation and informs remediation design and monitoring.

Comparison of Shear Strength Properties for Undisturbed and Reconstituted Parit Nipah Peat, Johor

NASA Astrophysics Data System (ADS)

Azhar, A. T. S.; Norhaliza, W.; Ismail, B.; Abdullah, M. E.; Zakaria, M. N.

2016-11-01

Shear strength of soil is required to determine the soil stability and design the foundations. Peat is known as a soil with complex natural formations which also contributes problems to the researchers, developers, engineers and contractors in constructions and infrastructures. Most researchers conducted experiment and investigation of shear strength on peat using shear box test and simple shear test, but only a few had discovered the behavior of peat using triaxial consolidated undrained test. The aim of this paper is to determine the undrained shear strength properties of reconstituted peat and undisturbed peat of Parit Nipah, Johor for comparison purposes. All the reconstituted peat samples were formed with the size that passed opening sieve 3.35 mm and preconsolidation pressure at 100 kPa. The result of undrained shear strength of reconstituted peat was 21kPa for cohesion with the angle of friction, 41° compare to the undisturbed peat with cohesion 10 kPa and angle of friction, 16°. The undrained shear strength properties result obtained shows that the reconstituted peat has higher strength than undisturbed peat. For relationship deviator stress-strain, σd max and excess pore pressure, Δu, it shows that both of undisturbed and reconstituted gradually increased when σ’ increased, but at the end of the test, the values are slightly dropped. The physical properties of undisturbed and reconstituted peat were also investigated to correlate with the undrained shear strength results.

U-Pb Geochronology of non-marine Upper Triassic strata of the Colorado Plateau (western North America): implications for stratigraphic correlation and paleoenvironmental reconstruction

NASA Astrophysics Data System (ADS)

Rasmussen, C.; Mundil, R.; Irmis, R. B.; Keller, C. B.; Giesler, D.; Gehrels, G. E.

2017-12-01

The Triassic is a critical period in Earth history that witnessed the origin of modern ecosystems and frequent climate fluctuations, as well as major environmental events such as flood basalt volcanism and bolide impacts. The Chinle Formation contains a primary non-marine archive for past ecosystems in North America due to its fossil richness and well-studied sedimentology. Moreover, within these highly fossiliferous strata, a biotic turnover has been reported that has been hypothesized to coincide with one or more of the aforementioned environmental events. Unfortunately, few radioisotopic ages have been published for the Late Triassic, limiting our ability for lithological and paleoenvironmental correlations. In addition, the superposition of the Chinle Formation remains illusive due to frequent lateral facies changes and discontinuous outcrops across the Colorado Plateau. The 520 m long core 1A of the Colorado Plateau Coring Project from Petrified Forest National Park (PFNP) (Arizona) provides, for the first time, a continuous section of these early Mesozoic sedimentary strata. Many of the sand- and siltstones from this continuous succession throughout most of the Upper Triassic Chinle Formation contain euhedral zircons suitable for U-Pb analyses. We analyzed >300 crystals each from 10 samples using LA-ICPMS; these results indicated abundant Late Triassic crystals that appear to be closely associated with the depositional age of the host rock. We then selected the youngest grains from these samples to obtain precise CA-TIMS U-Pb single zircon ages in order to constrain the maximum depositional ages (using quantitative methods) of these formations. We are able to revise the proposed time scale (based on outcrop samples) for Upper Triassic strata at PFNP and evaluate whether the biotic turnover observed within the Sonsela Member of these strata coincides with the Manicouagan bolide impact event. This revised chronostratigraphic framework allows intercalibration with the Newark astrochronostratigraphic polarity time scale and the correlation with other key non-marine and marine Late Triassic sections globally (e.g., Ischigualasto-Villa Uníon Basin, Argentina; Tethyan region, Europe) improving our understanding of paleoenvironmental and evolutionary changes during the Triassic.

40Ar/39Ar dating of a Langhian biotite-rich clay layer in the pelagic sequence of the Cònero Riviera, Ancona, Italy

NASA Astrophysics Data System (ADS)

Mader, Dieter; Montanari, Alessandro; Gattacceca, Jérôme; Koeberl, Christian; Handler, Robert; Coccioni, Rodolfo

2001-12-01

A nearly complete and undisturbed Miocene carbonate sequence is present in the easternmost part of the Umbria-Marche basin, Italy, which is ideal for detailed and integrated stratigraphic investigations of the Miocene Epoch. In this study, we were trying to obtain evidence for the presence or absence of distal ejecta from the 15 Ma Ries impact structure in southern Germany, located about 600 km to the north-northwest of the Umbria-Marche basin. The first step is to find coeval strata in the Umbria-Marche sequence. At the La Vedova section, Cònero Riviera, we dated a volcaniclastic biotite-rich clay layer, the Aldo Level, which is situated within planktonic foraminiferal Zone N8, at 14.9±0.2 Ma, using the 40Ar/39Ar method. Together with detailed geologic and stratigraphic information about the Aldo Level, the resulting age can be used confidentially to calibrate the Langhian stage. Besides providing new constraints on Miocene geochronology, this age can now be used for impact stratigraphic studies. To directly correlate the biotite ages of the La Vedova section with rocks from the Ries impact event, Ries impact glass was also analyzed and found to be coeval. Although unrelated to this impact event, the biotite-rich clay layer should help in the search for evidence of distal ejecta related to the Ries crater.

Darkness after the K-T impact: Effects of soot

NASA Technical Reports Server (NTRS)

Wolbach, Wendy S.; Anders, Edward; Orth, Charles J.

1988-01-01

Dust from the K-T impact apparently settled from the atmosphere in less than 6 months, restoring sunlight to minimum photosynthesis levels in about 4 months. However, the discovery of a global soot component in the boundary clay makes it necessary to reconsider the problem, as soot particles not only are smaller (0.1 vs. about 0.5 micrometer) and thus settle more slowly, but also are better light absorbers (optical depth of 13 mg soot cm(-2) about 1800; and are more resistant to rainout. Still, the darkness cannot have lasted very much longer than 6 months, else no larger animals would have survived. Perhaps the soot coagulated with the rock dust and fell out with it. Evidence on this point may be sought at a relatively undisturbed K-T boundary site, such as Woodside Creek, N.Z. There the boundary clay and lowermost Tertiary strata are finely laminated and show large chemical and isotopic differences on a millimeter scale, apparently representing a detailed time sequence. Researchers studied a 3 m section across the boundary at this site, analyzing the principal forms of carbon (soot, elemental C, kerogen, and carbonate) as well as 33 elements. Correlations among the elements were sought. Apparently soot came early and coagulated with the ejecta, staying with them for the primary fallout and in the next 5 cm, but then parting company, perhaps due to size sorting.

Accumulation of sediment-associated viruses in shellfish.

PubMed Central

Landry, E F; Vaughn, J M; Vicale, T J; Mann, R

1983-01-01

The present study focused on the importance of contaminated sediments in shellfish accumulation of human viruses. Epifaunal (Crassostrea virginica) and infaunal (Mercenaria mercenaria) shellfish, placed on or in cores, were exposed to either resuspended or undisturbed sediments containing bound poliovirus type 1 (LSc 2ab). Consistent bioaccumulation by oysters (four of five trials) was only noted when sediment-bound viruses occurred in the water column. Virus accumulation was observed in a single instance where sediments remained in an undisturbed state. While the incidence of bioaccumulation was higher with resuspended rather than undisturbed contaminated sediment, the actual concentration of accumulated viruses was not significantly different. The accumulation of viruses from oysters residing on uninoculated sediments. When clams were exposed to undisturbed, virus-contaminated sediments, two of five shellfish pools yielded viral isolates. Bioaccumulation of undisturbed sediments by these bivalves was considered marginal when related to the concentration of virus in contaminated sediments; they would only represent a significant threat when suspended in the water column. Arguments were advanced for water-column sampling in the region of the water-sediment interface to provide an accurate determination of the virological quality of shellfish harvesting waters. PMID:6297392

Submarine-fan sedimentation, Ouachita Mountains, Arkansas and Oklahoma

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

Moiola, R.J.; Shanmugam, G.

1984-09-01

More than 10,000 m (32,808 ft) of interbedded sandstones and shales comprise the Upper Mississippian and Lower Pennsylvanian flysch succession (Stanley, Jackfork, Johns Valley, Atoka) in the Ouachita Mountains of Arkansas and Oklahoma. Deposited primarily by turbidity current and hemipelagic processes in bathyal and abyssal water depths, these strata formed major submarine-fan complexes that prograded in a westward direction along the axis of an elongate remnant ocean basin that was associated with the collision and suturing of the North American and African-South American plates. A longitudinal fan system is visualized as the depositional framework for these strata, which were depositedmore » in a setting analogous to the modern Bengal fan of the Indian Ocean. Facies analysis of the Jackfork formation indicates that inner fan deposits are present in the vicinity of Little Rock, Arkansas; middle fan channel and interchannel deposits occur at DeGray Dam and Friendship, Arkansas; and outer fan depositional-lobe deposits are present in southeastern Oklahoma. Boulder-bearing units (olistostromes), many with exotic clasts, were shed laterally into the Ouachita basin. They occur throughout the flysch succession and in all fan environments (i.e., inner, middle, and outer). This relationship may serve as a useful criterion for recognizing analogous longitudinal fan systems in the rock record.« less

Paleomagnetism of a well-dated marine succession in South China: A possible Late Cambrian true polar wander (TPW)

NASA Astrophysics Data System (ADS)

Jiao, Wen-Jun; Li, Yong-Xiang; Yang, Zhen-Yu

2018-04-01

The Cambrian true polar wander (TPW) hypothesis remains controversial largely because of the uncertainties in the quality and/or fidelity of the paleomagnetic data as well as their chronological control. Testing the TPW hypothesis requires high-quality paleomagnetic data of sufficient spatial and temporal resolutions. Here, we present paleomagnetic results of a continuous Cambrian shallow marine succession from South China where available detailed biostratigraphy provides exceptional chronological constraints. Forty-three sites of paleomagnetic samples were collected from this limestone-dominated succession. Stepwise thermal demagnetization generally reveals three-component magnetizations. Low- and intermediate-temperature components can be cleaned by ∼330 °C, and the high-temperature component (HTC) was isolated typically from ∼350 to ∼450 °C. A positive fold test and the presence of reversed polarity in the strata, together with rock magnetic data as well as the scanning electron microscopic (SEM) and transmission electron microscopic (TEM) results, collectively suggest that the HTCs are likely primary. A directional shift of the HTCs occurs between the lower-middle Cambrian and the upper Cambrian strata in the succession and is tentatively interpreted to indicate a ∼57° polar wander from ∼500.5 to 494 Ma. Because the rate of polar wander is too fast to be a tectonic origin, this polar wander is interpreted to represent a Late Cambrian TPW. This TPW appears coeval with the Steptoean positive carbon isotope excursion (SPICE) and the major trilobite mass extinctions, suggesting a potential link between the TPW and the Late Cambrian biotic and climatic changes. Because the proposed TPW event is exceptionally well-dated, it should be testable through examination of other worldwide sections.

[Effects of human engineering activities on permafrost active layer and its environment in northern Qinghai-Tibetan plateau].

PubMed

Guo, Zhenggang; Wu, Qingbo; Niu, Fujun

2006-11-01

With disturbed and undisturbed belts during the construction of Qinghai-Tibet highway as test objectives, this paper studied the effects of human engineering activities on the permafrost ecosystem in northern Qinghai-Tibetan plateau. The results showed that the thickness of permafrost active layer was smaller in disturbed than in undisturbed belt, and decreased with increasing altitude in undisturbed belt while no definite pattern was observed in disturbed belt. Different vegetation types had different effects on the thickness of permafrost active layer, being decreased in the order of steppe > shrub > meadow. In the two belts, altitude was the main factor affecting the vertical distribution of soil moisture, but vegetation type was also an important affecting factor if the altitude was similar. Due to the human engineering activities, soil temperature in summer was lower in disturbed than in undisturbed belt.

Correlations among stand ages and forest strata in mixed-oak forests of southeastern Ohio

Treesearch

P. Charles Goebel; David M. Hix

1997-01-01

Many models of landscape ecosystem development, as well as of forest stand dynamics, are based upon spatial and temporal changes in the species composition and structure of various forest strata. However, few document the interrelationships among forest strata, or the response of different strata to alterations of natural disturbance regimes. To examine how...

43 CFR 2806.32 - How does BLM determine the population strata served?

Code of Federal Regulations, 2014 CFR

2014-10-01

... 43 Public Lands: Interior 2 2014-10-01 2014-10-01 false How does BLM determine the population... does BLM determine the population strata served? (a) BLM determines the population strata served as follows: (1) If the site or facility is within a designated RMA, BLM will use the population strata of the...

43 CFR 2806.32 - How does BLM determine the population strata served?

Code of Federal Regulations, 2012 CFR

2012-10-01

... 43 Public Lands: Interior 2 2012-10-01 2012-10-01 false How does BLM determine the population... does BLM determine the population strata served? (a) BLM determines the population strata served as follows: (1) If the site or facility is within a designated RMA, BLM will use the population strata of the...

43 CFR 2806.32 - How does BLM determine the population strata served?

Code of Federal Regulations, 2011 CFR

2011-10-01

... 43 Public Lands: Interior 2 2011-10-01 2011-10-01 false How does BLM determine the population... does BLM determine the population strata served? (a) BLM determines the population strata served as follows: (1) If the site or facility is within a designated RMA, BLM will use the population strata of the...

43 CFR 2806.32 - How does BLM determine the population strata served?

Code of Federal Regulations, 2013 CFR

2013-10-01

... 43 Public Lands: Interior 2 2013-10-01 2013-10-01 false How does BLM determine the population... does BLM determine the population strata served? (a) BLM determines the population strata served as follows: (1) If the site or facility is within a designated RMA, BLM will use the population strata of the...

Stratigraphy and lithofacies of Lisburne Group carbonate rocks (Carboniferous - Permian) in the National Petroleum Reserve - Alaska

USGS Publications Warehouse

Dumoulin, Julie A.; Bird, Kenneth J.; Houseknecht, David W.

2001-01-01

Carbonate rocks of the Lisburne Group (Carboniferous-Permian) occur widely throughout northern Alaska. In the NPRA, seismic mapping and well penetrations show that the Lisburne occurs throughout the subsurface except in northernmost NPRA where it is missing by depositional onlap. Lisburne strata encountered in 11 exploratory wells in the northern part of the NPRA are essentially undeformed, consist of limestone and lesser dolostone, sandstone, siltstone, and shale, encompass a wide array of chiefly shallow-water facies, and range in age from Early Mississippian to Permian. Basins and platforms that formed during Mississippian (and possibly Devonian) time greatly affected depositional patterns of the Lisburne. Total thickness of the Lisburne in northern NPRA wells varies from almost 4000 ft in the Ikpikpuk-Umiat Basin to 300 ft on the north edge of the Fish Creek Platform. Lisburne strata of Mississippian age are found in northeastern NPRA, comprise three subunits (lower limestone, middle dolostone, and upper limestone) and are oldest (Osagean) in the Ikpikpuk-Umiat Basin. All wells that penetrated the Lisburne in northern NPRA encountered rocks of Pennsylvanian age; these intervals are mainly limestone and characterized by decameter-scale shallowing-upward sequences. Lisburne sections of prob-able Early-middle Permian age range from thin (≤60 ft) intervals of dolostone and limestone in the Fish Creek Platform area to thick (500-1000 ft) successions of interbedded limestone and siliciclastic sediment in the Ikpikpuk-Umiat Basin and northwestern NPRA. Abundant non-carbonate detritus, primarily quartz and chert with locally notable plagioclase feldspar and metamorphic lithic clasts, occurs throughout the Lisburne Group in northern NPRA. Per-mian strata and a persistent non-carbonate detrital component are also seen in the Lisburne in subsurface beneath the Chukchi Sea (Hanna Trough) to the northwest, but are not found in Lisburne successions elsewhere in Alaska.

Paleocurrents of the Middle-Upper Jurassic strata in the Paradox Basin, Colorado, inferred from anisotropy of magnetic susceptibility (AMS)

NASA Astrophysics Data System (ADS)

Ejembi, J. I.; Ferre, E. C.; Potter-McIntyre, S. L.

2017-12-01

The Middle-Upper Jurassic sedimentary strata in the southwestern Colorado Plateau recorded pervasive eolian to fluvio-lacustrine deposition in the Paradox Basin. While paleocurrents preserved in the Entrada Sandstone, an eolian deposition in the Middle Jurassic, has been well constrained and show a northwesterly to northeasterly migration of ergs from the south onto the Colorado Plateau, there is yet no clear resolution of the paleocurrents preserved in the Wanakah Formation and Tidwell Member of the Morrison Formation, both of which are important sedimentary sequences in the paleogeographic framework of the Colorado Plateau. New U-Pb detrital zircon geochronology of sandstones from these sequences suggests that an abrupt change in provenance occurred in the early Late Jurassic, with sediments largely sourced from eroding highlands in central Colorado. We measured the anisotropy of magnetic susceptibility (AMS) of sediments in oriented sandstone samples from these three successive sequences; first, to determine the paleocurrents from the orientations of the AMS fabrics in order to delineate the source area and sediments dispersal pattern and second, to determine the depositional mechanisms of the sediments. Preliminary AMS data from two study sites show consistency and clustering of the AMS axes in all the sedimentary sequences. The orientations of the Kmin - Kint planes in the Entrada Sandstone sample point to a NNE-NNW paleocurrent directions, which is in agreement with earlier studies. The orientations of the Kmin - Kint planes in the Wanakah Formation and Tidwell Member samples show W-SW trending paleocurrent directions, corroborating our hypothesis of a shift in provenance to the eroding Ancestral Front Range Mountain, located northeast of the Paradox Basin, during the Late Jurassic. Isothermal remanence magnetization (IRM) of the samples indicate that the primary AMS carriers are detrital, syndepositional ferromagnetic minerals. Thus, we contend that AMS can be successfully deployed in constraining paleocurrents in lacustrine sedimentary strata, which lacks traditional sedimentary structures for paleocurrent analyses.

Late Devonian glacigenic and associated facies from the central Appalachian Basin, eastern United States

USGS Publications Warehouse

Brezinski, D.K.; Cecil, C.B.; Skema, V.W.

2010-01-01

Late Devonian strata in the eastern United States are generally considered as having been deposited under warm tropical conditions. However, a stratigraphically restricted Late Devonian succession of diamictite- mudstonesandstone within the Spechty Kopf and Rockwell Formations that extends for more than 400 km along depositional strike within the central Appalachian Basin may indicate other wise. This lithologic association unconformably overlies the Catskill Formation, where a 3- to 5-m-thick interval of deformed strata occurs immediately below the diamictite strata. The diamictite facies consists of several subfacies that are interpreted to be subglacial, englacial, supraglacial meltout, and resedimented deposits. The mudstone facies that overlies the diamictite consists of subfacies of chaotically bedded, clast-poor mudstone, and laminated mudstone sub facies that represent subaqueous proximal debris flows and distal glaciolacustrine rhythmites or varvites, respectively. The pebbly sandstone facies is interpreted as proglacial braided outwash deposits that both preceded glacial advance and followed glacial retreat. Both the tectonic and depositional frameworks suggest that the facies were deposited in a terrestrial setting within the Appalachian foreland basin during a single glacial advance and retreat. Regionally, areas that were not covered by ice were subject to increased rainfall as indicated by wet-climate paleosols. River systems eroded deeper channels in response to sea-level drop during glacial advance. Marine facies to the west contain iceborne dropstone boulders preserved within contemporaneous units of the Cleveland Shale Member of the Ohio Shale.The stratigraphic interval correlative with sea-level drop, climate change, and glacigenic succession represents one of the Appalachian Basin's most prolific oil-and gas-producing intervals and is contemporaneous with a global episode of sea-level drop responsible for the deposition of the Hangenberg Shale/Sandstone of Europe. This interval records the Hangenberg biotic crisis near the Devonian-Carboniferous boundary. ?? 2009 Geological Society of America.

COLLECTION OF UNDISTURBED SURFACE SEDIMENTS

EPA Science Inventory

The National Resource Council identified the need for a capability to collect undisturbed surface sediments. Surface sediments are an important source for most exposure of fish to polychlorinated biphenyls via direct uptake from water in contact with sediments. An innovative sedi...

Microbial secondary succession in soil microcosms of a desert oasis in the Cuatro Cienegas Basin, Mexico.

PubMed

López-Lozano, Nguyen E; Heidelberg, Karla B; Nelson, William C; García-Oliva, Felipe; Eguiarte, Luis E; Souza, Valeria

2013-01-01

Ecological succession is one of the most important concepts in ecology. However for microbial community succession, there is a lack of a solid theoretical framework regarding succession in microorganisms. This is in part due to microbial community complexity and plasticity but also because little is known about temporal patterns of microbial community shifts in different kinds of ecosystems, including arid soils. The Cuatro Cienegas Basin (CCB) in Coahuila, Mexico, is an arid zone with high diversity and endemisms that has recently been threatened by aquifer overexploitation. The gypsum-based soil system of the CCB is one of the most oligotrophic places in the world. We undertook a comparative 16S rRNA 454 pyrosequencing study to evaluate microbial community succession and recovery over a year after disturbance at two sites. Results were related to concurrent measurements of humidity, organic matter and total C and N content. While each site differed in both biogeochemistry and biodiversity, both present similar pattern of change at the beginning of the succession that diverged in later stages. After one year, experimentally disturbed soil was not similar to established and undisturbed adjacent soil communities indicating recovery and succession in disturbed soils is a long process.

Variation in the immune responses against Plasmodium falciparum merozoite surface protein-1 and apical membrane antigen-1 in children residing in the different epidemiological strata of malaria in Cameroon.

PubMed

Kwenti, Tebit Emmanuel; Moye, Adzemye Linus; Wiylanyuy, Adzemye Basil; Njunda, Longdoh Anna; Nkuo-Akenji, Theresa

2017-11-09

Studies to assess the immune responses against malaria in Cameroonian children are limited. The purpose of this study was to assess the immune responses against Plasmodium falciparum merozoite surface protein-1 (MSP-1 19 ) and apical membrane antigen-1 (AMA-1) in children residing in the different epidemiological strata of malaria in Cameroon. In a cross-sectional survey performed between April and July 2015, 602 children between 2 and 15 years (mean ± SD = 5.7 ± 3.7), comprising 319 (53%) males were enrolled from five epidemiological strata of malaria in Cameroon including: the sudano-sahelian (SS) strata, the high inland plateau (HIP) strata, the south Cameroonian equatorial forest (SCEF) strata, the high western plateau (HWP) strata, and the coastal (C) strata. The children were screened for clinical malaria (defined by malaria parasitaemia ≥ 5000 parasites/µl plus axillary temperature ≥ 37.5 °C). Their antibody responses were measured against P. falciparum MSP-1 19 and AMA-1 vaccine candidate antigens using standard ELISA technique. A majority of the participants were IgG responders 72.1% (95% CI 68.3-75.6). The proportion of responders was higher in females (p = 0.002) and in children aged 10 years and above (p = 0.005). The proportion of responders was highest in Limbe (C strata) and lowest in Ngaoundere (HIP strata) (p < 0.0001). Similarly, the mean IgG antibody levels were higher in children aged 10 years and above (p < 0.0001) and in Limbe (p = 0.001). The IgG antibody levels against AMA-1 were higher in females (p = 0.028), meanwhile no gender disparity was observed with MSP-1. Furthermore the risk of clinical malaria (p < 0.0001) and the mean parasite density (p = 0.035) were higher in IgG non-responders. A high proportion of IgG responders was observed in this study, suggesting a high degree exposure of the target population to malaria parasites. The immune responses varied considerably across the different strata: the highest levels observed in the C strata and the lowest in the HIP strata. Furthermore, malaria transmission in Cameroon could be categorized into two major groups based on the serological reaction of the children: the southern (comprising C and SCEF strata) and northern (comprising HWP, HIP and SS strata) groups. These findings may have significant implications in the design of future trials for evaluating malaria vaccine candidates in Cameroon.

40 CFR 434.64 - Procedure and method detection limit for measurement of settleable solids.

Code of Federal Regulations, 2011 CFR

2011-07-01

... thoroughly mixed sample. Allow to settle undisturbed for 45 minutes. Gently stir along the inside surface of the cone with a stirring rod. Allow to settle undisturbed for 15 minutes longer. Record the volume of...

40 CFR 434.64 - Procedure and method detection limit for measurement of settleable solids.

Code of Federal Regulations, 2010 CFR

2010-07-01

... thoroughly mixed sample. Allow to settle undisturbed for 45 minutes. Gently stir along the inside surface of the cone with a stirring rod. Allow to settle undisturbed for 15 minutes longer. Record the volume of...

Mid and Late Devonian arenites deposited by sheet-flood, braided streams and rivers in the northern Barrier Ranges, far western New South Wales, Australia

NASA Astrophysics Data System (ADS)

Neef, G.; Bottrill, R. S.; Cohen, D. R.

1996-05-01

Extensive and well exposed, fine-grained fluvial sandstone and less common pebbly coarse-grained fluvial sandstone of Devonian age, crop out in the northern Barrier Ranges of far west New South Wales, Australia. These strata were deposited largely on low-gradient alluvial fans in a basin and range landscape and contain common sedimentary structures (especially streaming lineations and tabular cross-beds). Around 400 of these sedimentary structures were measured to determine the palaeoflow trends of the sheet floods, streams or rivers which deposited the sandstone. The strata are mapped as the Mid Devonian Coco Range Sandstone and the Late Devonian Nundooka Sandstone, which together are around 2.7 km thick. They were deposited at the western margin of the large Emsian to Early Carboniferous Darling Basin. The Coco Range Sandstone is Emsian to Eifelian in age (based on fragments) of fossil fish) and it is separated from the Frasnian-Famennian (Late Devonian) Nundooka Sandstone by the north-trending Nundooka Creek Fault. The eastern boundary of the Nundooka Sandstone is formed by the Western Boundary Fault. Eastward of this fault is the north-trending and 40 km wide Bancannia Trough, which contains gently folded Late Silurian to Early Carboniferous strata up to 7.5 km thick. Most of the Coco Range Sandstone and all of the Nundooka Sandstone are non-graded, fine and very fine-grained, light brown sub-litharenites which are considered to have been deposited mainly on low-gradient alluvial fans. Sedimentary successions of 1.75 to 5.25 m thickness in the fine-grained arenite usually commence with Sm (massive or slumped) → Sh (laminated arenite) or St (trough cross-beds) → Sp (tabular cross-bedded sandstone). An erosional surface commonly underlies the sedimentary successions and they are interpreted to be the result of deposition from decelerating sheet floods. Units composed of tabular cross-bedded strata several metres thick are rarely channelised and are interpreted to represent deposition within braided streams flowing upon the fans or deposited at the margin of sheet floods. In the Coco Range Sandstone there are two sheet-like coarse pebbly arenite units (The Valley Tank and Copi Dam Members) which together total 200 m in thickness. Unimodal palaeocurrent trends and heavy mineral suites from within the coarse-grained arenite indicate a derivation from the south near Broken Hill. Sedimentary structures within the coarse-grained arenite indicate a Platte River style of deposition upon distal braid plains, whereas local interdigitation of coarse-grained arenite with fine arenite strata shows that deposition was essentially continuous (i.e. the coarse arenite do not overlie unconformities) and the two lithotypes represent interdigitation of alluvial fans and braid plain deposition. The northward progradation of the coarse arenite units was probably due to a sudden retardation of basement downwarping.

New Early Triassic trace fossil records from South China: implications for biotic recovery following the end-Permian mass extinction

NASA Astrophysics Data System (ADS)

Luo, M.; George, A. D.; Chen, Z.; Zhang, Y.

2013-12-01

New Early Triassic trace fossil assemblages are documented from the Susong and Tianshengqiao areas in South China to evaluate the mode and tempo of biotic recovery of epifaunal and infaunal organisms following the end-Permian mass extinction. The Susong succession is exposed in Anhui area of the Lower Yangtze region and comprises mudstone and carbonate facies that record overall shallowing from offshore to supratidal settings. The Tianshengqiao succession crops out in the Luoping area, Yuannan Province of the Upper Yangtze region, and consists of mixed carbonate and siliciclastic facies which were deposited in shallow marine to offshore settings. Bivalve and conodont biostratigraphy helps constrain the chronostratigraphic framework of the Lower Triassic successions in these two sections. Griesbachian to Dieneria ichnological records in both successions are characterized by low ichnodiversity, low ichnofabric indices (ii=1-2) and low bedding plane bioturbation indices (bpbi=1-2). Higher ii (ii= 3 and 4) corresponding to densely populated diminutive Skolithos in the Tianshengqiao succession suggest an opportunistic strategy during earliest Triassic deposition. Ichnological data from the Susong succession show an increase in ichnodiversity during the Smithian. A total of 12 ichnogenera including Arenicolites, Chondrites, Gyrochorte, Laevicyclus, Monocraterion, Palaeophycus, Phycodes, Plaolites, Thalassinoides, Treptichnus, Trichichnus and one problematic trace are identified. Ichnofabric indices (ii) and bpbi increase to moderate to high levels (ii = 4-5, bpbi= 3-5). Although complex traces such as Rhizocorallium are in Spathian strata in this section, the low levels of ichnodiversity, ichnofabric indices and diminutive Planolites suggest a decline in recovery. In the Tianshengqiao succession, ichnofabric indices exhibit a moderate to high value (ii= 3 to 5), however, only six ichnogenera are found and Planolites burrows are consistently small (average diameter at 3.7 mm) in the Smithian strata. These stressed ichnological parameters remain unchanged during the Spathian. Complex traces such as large Rhizocorallium and Thalassinoides and large sized Planolites (average diameter is 6.9 mm) did not appear until the Anisian. Ichnological results from both successions record the response of organisms to prolonged unfavorable environmental conditions although trace fossils from the Susong succession show evidences for recovery during the Smithian followed by a decline. This maybe resulted from a recognised temperature spike at the Smithian/Spathian boundary in South China and elsewhere. Ichnological data from the Tianshengqiao succession suggests a protracted recovery throughout the Early Triassic.

Integrated multi-stratigraphic study of the Coll de Terrers late Permian-Early Triassic continental succession from the Catalan Pyrenees (NE Iberian Peninsula): A geologic reference record for equatorial Pangaea

NASA Astrophysics Data System (ADS)

Mujal, Eudald; Fortuny, Josep; Pérez-Cano, Jordi; Dinarès-Turell, Jaume; Ibáñez-Insa, Jordi; Oms, Oriol; Vila, Isabel; Bolet, Arnau; Anadón, Pere

2017-12-01

The most severe biotic crisis on Earth history occurred during the Permian-Triassic (PT) transition around 252 Ma. Whereas in the marine realm such extinction event is well-constrained, in terrestrial settings it is still poorly known, mainly due to the lack of suitable complete sections. This is utterly the case along the Western Tethys region, located at Pangaea's equator, where terrestrial successions are typically build-up of red beds often characterised by a significant erosive gap at the base of the Triassic strata. Henceforth, documenting potentially complete terrestrial successions along the PT transition becomes fundamental. Here, we document the exceptional Coll de Terrers area from the Catalan Pyrenees (NE Iberian Peninsula), for which a multidisciplinary research is conducted along the PT transition. The red-bed succession, located in a long E-W extended narrow rift system known as Pyrenean Basin, resulted from a continuous sedimentary deposition evolving from meandering (lower Upper Red Unit) to playa-lake/ephemeral lacustrine (upper Upper Red Unit) and again to meandering settings (Buntsandstein facies). Sedimentary continuity is suggested by preliminary cyclostratigraphic analysis that warrants further analysis. Our combined sedimentological, mineralogical and geochemical data infer a humid-semiarid-humid climatic trend across the studied succession. The uppermost Permian strata, deposited under an orbitally controlled monsoonal regime, yields a relatively diverse ichnoassemblage mainly composed of tetrapod footprints and arthropod trace fossils. Such fossils indicate appropriate life conditions and water presence in levels that also display desiccation structures. These levels alternate with barren intervals formed under dry conditions, being thus indicative of strong seasonality. All these features are correlated with those reported elsewhere in Gondwana and Laurasia, and suggest that the Permian-Triassic boundary might be recorded somewhere around the Buntsandstein base. Consequently, Coll de Terrers and the whole Catalan Pyrenees become key regions to investigate in detail the Permian extinction event and the Triassic ecosystems recovery.

Socioeconomic rehabilitation of successful renal transplant patients and impact of funding source: Indian scenario.

PubMed

Kapoor, Rakesh; Sharma, Raj Kumar; Srivastava, Aneesh; Kapoor, Rohit; Arora, Sohrab; Sureka, Sanjoy Kumar

2015-01-01

Socio-economic rehabilitation is an important outcome parameter in successful renal transplant recipients, particularly in developing countries with low income patients who often depend on extraneous sources to fund their surgery costs. We studied the socioeconomic rehabilitation and changes in socioeconomic status (SES) of successful renal allograft recipients among Indian patients and its correlation with their source of funding for the surgery. A cross-sectional, questionnaire-based study was conducted on 183 patients between January 2010 to January 2013. Patients with follow up of at least 1 year after successful renal transplant were included. During interview, two questionnaires were administered, one related to the SES including source of funding before transplantation and another one relating to the same at time of interview. Changes in SES were categorized as improvement, stable and deterioration if post-transplant SES score increased >5%, increased or decreased by <5% and decreased >5% of pre-transplant value, respectively. In this cohort, 97 (52.7%), 67 (36.4%) and 19 (10.3%) patients were non-funded (self-funded), one-time funded and continuous funded, respectively. Fifty-six (30.4%) recipients had improvement in SES, whereas 89 (48.4%) and 38 (20.7%) recipients had deterioration and stable SES. Improvement in SES was seen in 68% patients with continuous funding support whereas, in only 36% and 12% patients with non-funded and onetime funding support (P = 0.001) respectively. Significant correlation was found (R = 0.715) between baseline socioeconomic strata and changes in SES after transplant. 70% of the patients with upper and upper middle class status had improving SES. Patients with middle class, lower middle and lower class had deterioration of SES after transplant in 47.4%, 79.6% and 66.7% patients, respectively. Most of the recipients from middle and lower social strata, which included more than 65% of our patient's population, had deteriorating SES even after a successful transplant. One-time funding source for transplant had significant negative impact on SES and rehabilitation.

Sedimentology and sequence stratigraphy of the Cretaceous Nanushuk, Seabee, and Tuluvak formations exposed on Umiat Mountain, north-central Alaska

USGS Publications Warehouse

Houseknecht, David W.; Schenk, Christopher J.

2005-01-01

Upper Cretaceous strata of the upper part of the Nanushuk Formation, the Seabee Formation, and the lower part of the Tuluvak Formation are exposed along the Colville River on the east flank of Umiat Mountain in north-central Alaska. The Ninuluk sandstone, which is the uppermost unit of the Nanushuk Formation, displays a vertical succession of facies indicative of deposition in an upward-deepening estuarine through shoreface setting. A marine-flooding surface lies between the Ninuluk sandstone and organic-rich shale of the basal part of the Seabee Formation. The Ninuluk sandstone and the lower part of the Seabee Formation are interpreted as components of a transgressive-systems tract. The lowest, well-exposed strata in the Seabee Formation are a succession of shoreface sandstone beds in the middle of the formation. Integration of outcrop information and the Umiat No. 11 well log suggests that this sandstone succession rests on a sequence boundary and is capped by a marine-flooding surface. The sandstone succession is interpreted as a lowstand-systems tract. The upper part of the Seabee Formation includes a thick interval of organic-rich shale deposited in a dysaerobic offshore environment, and the gradational Seabee-Tuluvak contact is a coarsening-upward shale-to-sandstone succession deposited in a prodelta/delta-front environment. The observation that the upper part of the Seabee Formation correlates with seismic clinoforms suggests that dysaerobic conditions extended well up onto the prodelta slope during intervals of transgression and highstand. Correlation of the Umiat Mountain outcrop section with well logs and seismic data suggests that sequence boundaries and lowstand shoreface deposits may be common in the Seabee Formation and that wave action may have been important in transporting sand to the paleoshelf margin. These conclusions may contribute to an enhanced understanding of sand distribution in prospective lowstand turbidite deposits in the subsurface of the central North Slope of Alaska.

Geology of an Ordovician stratiform base-metal deposit in the Long Canyon Area, Blaine County, Idaho

USGS Publications Warehouse

Otto, B.R.; Zieg, G.A.

2003-01-01

In the Long Canyon area, Blaine County, Idaho, a strati-form base-metal-bearing gossan is exposed within a complexly folded and faulted sequence of Ordovician strata. The gossan horizon in graptolitic mudrock suggests preservation of bedded sulfides that were deposited by an Ordovician subaqueous hydrothermal system. Abrupt thickness changes and geochemi-cal zoning in the metal-bearing strata suggest that the gossan is near the source of the hydrothermal system. Ordovician sedimentary rocks at Long Canyon represent a coarsening-upward section that was deposited below wave base in a submarine depositional environment. The lowest exposed rocks represent deposition in a starved, euxinic basin and over-lying strata represent a prograding clastic wedge of terrigenous and calcareous detritus. The metalliferous strata are between these two types of strata. Strata at Long Canyon have been deformed by two periods of thrust faulting, at least three periods of normal faulting, and two periods of folding. Tertiary extensional faulting formed five subhorizontal structural plates. These low-angle fault-bounded plates truncate Sevier-age and possibly Antler-age thrust faults. The presence of gossan-bearing strata in the four upper plates suggests that there was only minor, although locally complex, stratigraphic displacement and rotation. The lack of correlative strata in the lowest plate suggests the displacement was greater than 2000 ft. The metalliferous strata were exposed to surface weathering, oxidation, and erosion prior to and during deposition of the Eocene Challis Volcanic Group. The orientations of erosional canyons formed during this early period of exposure were related to the orientations of Sevier-age thrust faults, and stream-channel gravel was deposited in the canyons. During this and subsequent intervals of exposure, sulfidic strata were oxi-dized to a minimum depth of 700 ft.

Macroinvertebrate community assembly in pools created during peatland restoration.

PubMed

Brown, Lee E; Ramchunder, Sorain J; Beadle, Jeannie M; Holden, Joseph

2016-11-01

Many degraded ecosystems are subject to restoration attempts, providing new opportunities to unravel the processes of ecological community assembly. Restoration of previously drained northern peatlands, primarily to promote peat and carbon accumulation, has created hundreds of thousands of new open water pools. We assessed the potential benefits of this wetland restoration for aquatic biodiversity, and how communities reassemble, by comparing pool ecosystems in regions of the UK Pennines on intact (never drained) versus restored (blocked drainage-ditches) peatland. We also evaluated the conceptual idea that comparing reference ecosystems in terms of their compositional similarity to null assemblages (and thus the relative importance of stochastic versus deterministic assembly) can guide evaluations of restoration success better than analyses of community composition or diversity. Community composition data highlighted some differences in the macroinvertebrate composition of restored pools compared to undisturbed peatland pools, which could be used to suggest that alternative end-points to restoration were influenced by stochastic processes. However, widely used diversity metrics indicated no differences between undisturbed and restored pools. Novel evaluations of restoration using null models confirmed the similarity of deterministic assembly processes from the national species pool across all pools. Stochastic elements were important drivers of between-pool differences at the regional-scale but the scale of these effects was also similar across most of the pools studied. The amalgamation of assembly theory into ecosystem restoration monitoring allows us to conclude with more certainty that restoration has been successful from an ecological perspective in these systems. Evaluation of these UK findings compared to those from peatlands across Europe and North America further suggests that restoring peatland pools delivers significant benefits for aquatic fauna by providing extensive new habitat that is largely equivalent to natural pools. More generally, we suggest that assembly theory could provide new benchmarks for planning and evaluating ecological restoration success. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

AN EARLY STAGE IN THE PLANT RECOLONIZATION OF A NUCLEAR TARGET AREA

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

Rickard, W.H.; Shields, L.M.

1963-01-01

Vegetational analyses were conducted three years postdetonation in a nuclear target area in a Grayia spinosa-Lycium andersonii community in Yucca Fiat, Nevada. Annual plants dominated the early stage of recolonization and were quantitatively more abundant in the disturbed areas than in an adjacent undisturbed shrub community. Ment zelia albicaulis and Chaenactis steviodes occurred in both disturbed and undisturbed areas, however; Mentzelia was more abundant in disturbed areas while Chaenactis was more abundant in the undisturbed community. Salsola kali was confined to disturbed areas while Phacelia vallismortae was more often encountered in the undisturbed community. The plant recolonization of a mechanicallymore » disturbed area was quantitatively and qualitatively more like that of the interior zone of the nuclear target area than less disturbed habitats. These data support a conclusion that soil displacement presents a more rigorous habitat for plant recolonization than disturbances created by the wider ranging destructive components of a nuclear detonation. (auth)« less

Volatile compounds released by disturbed and undisturbed adults of Anchomenus dorsalis (Coleoptera, Carabidae, Platynini) and structure of the pygidial gland

PubMed Central

Bonacci, Teresa; Brandmayr, Pietro; Zetto, Tullia; Perrotta, Ida Daniela; Guarino, Salvatore; Peri, Ezio; Colazza, Stefano

2011-01-01

Abstract Volatile compounds produced by adults of Anchomenus dorsalis under undisturbed and disturbed conditions were investigated with an all-glass aeration apparatus. GC-MS analysis of the crude extracts from undisturbed and disturbed adults highlighted four major volatile compounds, undecane, heneicosane, Z-9 tricosene and tricosane, of which significantly more undecane was released by disturbed adults compared to undisturbed beetles. The pygidial glands of adults of Anchomenus dorsalis were investigated using light and Transmission Electron Microscopy (TEM). Each gland showed dense aggregates of secretory cells organized into visually distinct lobes; a long collecting canal that drains the secretion towards the reservoir, a bean-shaped double lobed muscular reservoir in which secretion is stored and a short duct (efferent duct) through which the secretion is discharged. The function of the pygidial glands and the possible role played by undecane as a defensive allomone and/or chemical signalling molecule are discussed. PMID:21594158

The lasting effects of tank maneuvers on desert soils and intershrub flora

USGS Publications Warehouse

Prose, Douglas V.; Wilshire, Howard G.

2000-01-01

Mojave Desert soils and intershrub flora sustained lasting disturbances during military training maneuvers initiated by General George Patton, Jr. in the 1940s, and during Operation Desert Strike in 1964. At six sites, mean desert pavement clast size was significantly smaller by 15% to 50% in single tank tracks compared to undisturbed surfaces. The finer-grained tracks yielded significantly higher surface reflectance values at two of three sites. At one site, Patton era tank tracks cross centuries-old "intaglios" and there was no significant difference in clast size between the disturbances. Full recovery of pavement surfaces may require a change in climate since pavements formed in Pleistocene times under climatic conditions that no longer exist. Tank tracks of both ages exhibited significant levels of soil compaction, as indicated by penetrometer resistance values that were 51% to 120% greater than those in undisturbed soils to 0.3 m depth. Soil bulk density in tracks was 4% to 6% higher than in undisturbed soils. Soil compaction lowered infiltration rates in tank tracks by 24% to 55% in comparison to undisturbed soils. Compaction has prevented the intershrub flora from recovering in tank tracks. Annual and herbaceous perennial plant density was higher by 13% to 56% in tank tracks than in undisturbed soils, but compaction has restricted the growth of individual plants. This was reflected in plant cover values, which were 3% to 16% lower in tank tracks than in undisturbed soils. Soil compaction also altered the species composition. Species with long taproots, such as Chaenactis fremontii, were reduced in density and cover in tank tracks, whereas grass species with shallow, fibrous root systems had large density increases in tracks. Another important element of the intershrub flora, cryptobiotic crust, exhibited a low rate of recovery from the impact of tank travel at one site. The cover of the most well-developed component of the crusts, growing on delicate soil pedicels in undisturbed soils, was reduced by 50% in tank tracks because of destruction and compaction of the uppermost soil layers.

Retention and remobilization of stabilized silver nanoparticles in an undisturbed loamy sand soil

USDA-ARS?s Scientific Manuscript database

Column experiments were conducted with undisturbed loamy sand soil under unsaturated conditions (around 90% saturation degree) to investigate the retention of surfactant stabilized silver nanoparticles (AgNPs) with various input concentration (Co), flow velocity, and ionic strength (IS), and the rem...

Empirical Bayes methods for smoothing data and for simultaneous estimation of many parameters.

PubMed Central

Yanagimoto, T; Kashiwagi, N

1990-01-01

A recent successful development is found in a series of innovative, new statistical methods for smoothing data that are based on the empirical Bayes method. This paper emphasizes their practical usefulness in medical sciences and their theoretically close relationship with the problem of simultaneous estimation of parameters, depending on strata. The paper also presents two examples of analyzing epidemiological data obtained in Japan using the smoothing methods to illustrate their favorable performance. PMID:2148512

Tertiary stratigraphy and basin evolution, southern Sabah (Malaysian Borneo)

NASA Astrophysics Data System (ADS)

Balaguru, Allagu; Nichols, Gary

2004-08-01

New mapping and dating of strata in the southern part of the Central Sabah Basin in northern Borneo has made it possible to revise the lithostratigraphy and chronostratigraphy of the area. The recognition in the field of an Early Miocene regional unconformity, which may be equivalent to the Deep Regional Unconformity recognised offshore, has allowed the development of a stratigraphic framework of groups and formations, which correspond to stages in the sedimentary basin development of the area. Below the Early Miocene unconformity lies ophiolitic basement, which is overlain by an accretionary complex of Eocene age and a late Paleogene deep water succession which formed in a fore-arc basin. The late Paleogene deposits underwent syn-depositional deformation, including the development of extensive melanges, all of which can be demonstrated to lie below the unconformity in this area. Some localised limestone deposition occurred during a period of uplift and erosion in the Early Miocene, following which there was an influx of clastic sediments deposited in delta and pro-deltaic environments in the Middle Miocene. These deltaic to shallow marine deposits are now recognised as forming two coarsening-upward successions, mapped as the Tanjong and Kapilit Formations. The total thickness of these two formations in the Central Sabah Basin amounts to 6000 m, only half of the previous estimates, although the total stratigraphic thickness of Cenozoic clastic strata in Sabah may be more than 20,000 m.

Controls on Middle Pennsylvanian peat-forming floras in the Eastern United States

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

Eble, C.F.

1992-01-01

Middle Pennsylvanian strata in the Central Appalachian Basin contain numerous coal beds that provide an opportunity to study changes in coal-spore floras on an intra- and inter-bed scale. Vertical spore abundance patterns within individual coal beds record the ecological dynamics, both biologic and edaphic, of peat-forming systems in this interval. Coal palynofloras of this interval show a stratigraphic change in composition. Early to Middle Pennsylvanian spore floras are largely dominated by Lycospora. Species of Densosporites, a small lycopsid genus, Granulatisporites, a fern/pteridosperm( )-allied genus, and Laevigatosporites, a calamite-related genus, commonly displace Lycospora vertically within these beds, reflecting patterns of ecologicalmore » succession. Spore floras from stratigraphically younger coal beds in this sequence exhibit similar intra-bed spore variation, but contain increased percentages of tree-fern spores, and tend to be more florally heterogeneous overall. Areas of clastic deposition within the swamps are also marked by changes in spore composition. These changes in coal palynology are paralleled by stratigraphic changes in coal appearance and associated strata composition. The proportion of dull'' coal lithotypes, frequency of clastic partings, and amount of coarse clastics in the enclosing strata all increase toward the top of this sequence. Climate may have been more important in determining the floral composition of Early through mid-Middle Pennsylvanian peat swamps, whereas climate, tectonics, and eustasy interacted to determine sediment volume and type in this interval.« less

Resilience of ponderosa and lodgepole pine forests to mountain pine beetle disturbance and limited regeneration

USGS Publications Warehouse

Briggs, Jenny S.; Hawbaker, Todd J.; Vandendriesche, Don

2015-01-01

After causing widespread mortality in lodgepole pine forests in North America, the mountain pine beetle (MPB) has recently also affected ponderosa pine, an alternate host species that may have different levels of resilience to this disturbance. We collected field data in ponderosa pine- and lodgepole pine-dominated forests attacked by MPB in Colorado and then simulated stand growth over 200 years using the Forest Vegetation Simulator. We compared scenarios of no disturbance with scenarios of MPB-caused mortality, both with and without regeneration. Results indicated that basal area and tree density recovered to predisturbance levels relatively rapidly (within 1‐8 decades) in both forest types. However, convergence of the disturbed conditions with simulated undisturbed conditions took longer (12‐20+ decades) and was delayed by the absence of regeneration. In MPB-affected ponderosa pine forests without regeneration, basal area did not converge with undisturbed conditions within 200 years, implying lower resilience in this ecosystem. Surface fuels accumulated rapidly in both forest types after MPB-induced mortality, remaining high for 3‐6 decades in simulations. Our results suggest that future patterns of succession, regeneration, fuel loading, climate, and disturbance interactions over long time periods should be considered in management strategies addressing MPB effects in either forest type, but particularly in ponderosa pine.

On the relative intensity of Poisson’s spot

NASA Astrophysics Data System (ADS)

Reisinger, T.; Leufke, P. M.; Gleiter, H.; Hahn, H.

2017-03-01

The Fresnel diffraction phenomenon referred to as Poisson’s spot or spot of Arago has, beside its historical significance, become relevant in a number of fields. Among them are for example fundamental tests of the super-position principle in the transition from quantum to classical physics and the search for extra-solar planets using star shades. Poisson’s spot refers to the positive on-axis wave interference in the shadow of any spherical or circular obstacle. While the spot’s intensity is equal to the undisturbed field in the plane wave picture, its intensity in general depends on a number of factors, namely the size and wavelength of the source, the size and surface corrugation of the diffraction obstacle, and the distances between source, obstacle and detector. The intensity can be calculated by solving the Fresnel-Kirchhoff diffraction integral numerically, which however tends to be computationally expensive. We have therefore devised an analytical model for the on-axis intensity of Poisson’s spot relative to the intensity of the undisturbed wave field and successfully validated it both using a simple light diffraction setup and numerical methods. The model will be useful for optimizing future Poisson-spot matter-wave diffraction experiments and determining under what experimental conditions the spot can be observed.

Precipitation and streamwater chemistry in an undisturbed watershed in southeast Alaska.

Treesearch

John D. Stednick

1981-01-01

Water chemistry samples have been taken from streamflow since 1976 and precipitation since 1978 in Indian River, an undisturbed watershed on Chichagof Island in Southeast Alaska. Volume weighted concentrations of total nitrogen, ammonium nitrogen, nitrate nitrogen, total phosphorus, orthophosphate, sulfate sulfur, chloride, bicarbonate, silica, calcium, magnesium,...

Invasibility of Mediterranean-Climate Rivers by Non-Native Fish: The Importance of Environmental Drivers and Human Pressures

PubMed Central

Ilhéu, Maria; Matono, Paula; Bernardo, João Manuel

2014-01-01

Invasive species are regarded as a biological pressure to natural aquatic communities. Understanding the factors promoting successful invasions is of great conceptual and practical importance. From a practical point of view, it should help to prevent future invasions and to mitigate the effects of recent invaders through early detection and prioritization of management measures. This study aims to identify the environmental determinants of fish invasions in Mediterranean-climate rivers and evaluate the relative importance of natural and human drivers. Fish communities were sampled in 182 undisturbed and 198 disturbed sites by human activities, belonging to 12 river types defined for continental Portugal within the implementation of the European Union's Water Framework Directive. Pumpkinseed sunfish, Lepomis gibbosus (L.), and mosquitofish, Gambusia holbrooki (Girard), were the most abundant non-native species (NNS) in the southern river types whereas the Iberian gudgeon, Gobio lozanoi Doadrio and Madeira, was the dominant NNS in the north/centre. Small northern mountain streams showed null or low frequency of occurrence and abundance of NNS, while southern lowland river types with medium and large drainage areas presented the highest values. The occurrence of NNS was significantly lower in undisturbed sites and the highest density of NNS was associated with high human pressure. Results from variance partitioning showed that natural environmental factors determine the distribution of the most abundant NNS while the increase in their abundance and success is explained mainly by human-induced disturbance factors. This study stresses the high vulnerability of the warm water lowland river types to non-native fish invasions, which is amplified by human-induced degradation. PMID:25372284

Waterfowl Conservation in the US Prairie Pothole Region: Confronting the Complexities of Climate Change

PubMed Central

Niemuth, Neal D.; Fleming, Kathleen K.; Reynolds, Ronald E.

2014-01-01

The Prairie Pothole Region (PPR) is the most important waterfowl production area in North America. However, waterfowl populations there are predicted to decline because of climate-related drying of wetlands. Consequently, changes in the geographic focus of PPR waterfowl conservation have been recommended, which could have long-lasting and costly impacts. We used a 40-year dataset of pond counts collected in the PPR to test hypotheses about climate-related drying. We assessed May (1974–2013) and July (1974–2003) pond numbers in 20 waterfowl survey strata to determine if trends in pond numbers were consistent with predictions of drying. We also assessed trends in precipitation and temperature for the 20 strata and developed models describing May pond numbers from 1974 through 2010 as a function of precipitation, temperature, the previous year’s pond numbers, and location. None of the 20 strata showed significant declines in May pond numbers, although seven strata showed increases over time. July pond numbers declined significantly in one stratum, and increased in seven strata. An index to hydroperiod showed significant increasing trends in three strata, and no strata had decreasing trends. Precipitation increased significantly in two strata and decreased in two from 1974 to 2010; no strata showed significant changes in temperature. The best linear model described pond numbers within all strata as a function of precipitation, temperature, the previous year’s pond numbers, and the latitude and longitude of the stratum, and explained 62% of annual variation in pond numbers. We hypothesize that direct effects of climate change on prairie pothole wetlands and waterfowl may be overshadowed by indirect effects such as intensified land use and increased pressure to drain wetlands. We recommend that an adaptive, data-driven approach be used to resolve uncertainties regarding direct and indirect effects of climate change on prairie wetlands and waterfowl, and guide future conservation efforts. PMID:24937641

Waterfowl conservation in the US Prairie Pothole Region: confronting the complexities of climate change.

PubMed

Niemuth, Neal D; Fleming, Kathleen K; Reynolds, Ronald E

2014-01-01

The Prairie Pothole Region (PPR) is the most important waterfowl production area in North America. However, waterfowl populations there are predicted to decline because of climate-related drying of wetlands. Consequently, changes in the geographic focus of PPR waterfowl conservation have been recommended, which could have long-lasting and costly impacts. We used a 40-year dataset of pond counts collected in the PPR to test hypotheses about climate-related drying. We assessed May (1974-2013) and July (1974-2003) pond numbers in 20 waterfowl survey strata to determine if trends in pond numbers were consistent with predictions of drying. We also assessed trends in precipitation and temperature for the 20 strata and developed models describing May pond numbers from 1974 through 2010 as a function of precipitation, temperature, the previous year's pond numbers, and location. None of the 20 strata showed significant declines in May pond numbers, although seven strata showed increases over time. July pond numbers declined significantly in one stratum, and increased in seven strata. An index to hydroperiod showed significant increasing trends in three strata, and no strata had decreasing trends. Precipitation increased significantly in two strata and decreased in two from 1974 to 2010; no strata showed significant changes in temperature. The best linear model described pond numbers within all strata as a function of precipitation, temperature, the previous year's pond numbers, and the latitude and longitude of the stratum, and explained 62% of annual variation in pond numbers. We hypothesize that direct effects of climate change on prairie pothole wetlands and waterfowl may be overshadowed by indirect effects such as intensified land use and increased pressure to drain wetlands. We recommend that an adaptive, data-driven approach be used to resolve uncertainties regarding direct and indirect effects of climate change on prairie wetlands and waterfowl, and guide future conservation efforts.

Uplift of continental crustal blocks adjacent to the Rancheria Basin-Guasare area: the effects of Maastrichtian-Paleocene collision along the southern Caribbean plate boundary

NASA Astrophysics Data System (ADS)

Bayona, G.; Montes, C.; Jaramillo, C.; Ojeda, G.; Cardona, A.; Pardo, A.; Lamus, F.

2007-05-01

In the Rancheria basin (RB) and Guasare area (GA), Maastrichtian-Paleocene synorogenic strata overlie the Aptian-Campanian carbonate platform. Nowadays, RB is bounded to the west by metamorphic-and-igneous cored Santa Marta massif, where Upper Cretaceous strata overlie unconformably pre-Cretaceous rocks. The eastern boundary of the RB is the Perija range that includes volcaniclastic and sedimentary rocks of Jurassic and Cretaceous age in the hanging-wall of a NW-verging, low-angle dipping thrust belt. The GA is on the eastern foothills of the Perija range and corresponds to the western boundary of the Maracaibo basin. Strata architecture, seismic reflectors, gravity, provenance, and paleocurrent analyses carried out in those basins constrain the timing and style of uplift of Santa Marta massif and Perija range, which are linked with tectonism along the southern Caribbean plate. Maastrichtian-Paleocene strata thicken eastward up to 2.2 km in the RB, and this succession includes (in stratigraphic order): foram-rich calcareous mudstone, oyster-pelecypod rich carbonate-siliciclastic strata, coal- bearing mudstones and feldspar-lithic-rich fluvial sandstones. Internal disconformities and truncations of seismic reflectors are identified to the west of the RB, but there are not major thrust faults at this part of the basin to explain such unconformities and truncations. In Early Paleocene, carbonates developed better to the west of the RB, whereas mixed carbonate-siliciclastic deposition continued toward the east of the RB. In early Late Paleocene, influx of terrigenous material (key grains=metamorphic, microcline and garnet fragments) derived from the Santa Marta massif increased to the west, but to the east of the RB and GA carbonate-siliciclastic and carbonate deposition continued, respectively. In mid-Late Paleocene, diachronous eastward advance of paralic/deltaic environments, tropical humid climate, and high subsidence rates favored production and preservation of peat in RB and GA. In the late Late Paleocene, inversion along a buried graben system under the Perija range explain supply toward RB and GA of micritic, volcanic, and sedimentary rock fragments, and the record of a thinner Upper Paleocene strata in the GA than in the RB. Tectonic subsidence in the RB was mainly related to pivoting of the Santa Marta massif as result of collision of the Maracaibo continental sub-plate with the southern margin of the Caribbean oceanic plate. This model explains the generation of accommodation space in the RB without faulting, denudation of upper crustal material of the Santa Marta massif, early capture of terrigenous detritus in the RB that favored carbonate deposition in the GA, the mechanism of initial inversion of the Perija range, and the present positive gravity anomaly under the Santa Marta massif.

Upper Cretaceous and Lower Jurassic strata in shallow cores on the Chukchi Shelf, Arctic Alaska: Chapter C in Studies by the U.S. Geological Survey in Alaska, vol. 15

USGS Publications Warehouse

Houseknecht, David W.; Craddock, William H.; Lease, Richard O.

2016-02-12

Shallow cores collected in the 1980s on the Chukchi Shelf of western Arctic Alaska sampled pre-Cenozoic strata whose presence, age, and character are poorly known across the region. Five cores from the Herald Arch foreland contain Cenomanian to Coniacian strata, as documented by biostratigraphy, geochronology, and thermochronology. Shallow seismic reflection data collected during the 1970s and 1980s show that these Upper Cretaceous strata are truncated near the seafloor by subtle angular unconformities, including the Paleogene mid-Brookian unconformity in one core and the Pliocene-Pleistocene unconformity in four cores. Sedimentary structures and lithofacies suggest that Upper Cretaceous strata were deposited in a low accommodation setting that ranged from low-lying coastal plain (nonmarine) to muddy, shallow-marine environments near shore. These observations, together with sparse evidence from the adjacent western North Slope, suggest that Upper Cretaceous strata likely were deposited across all of Arctic Alaska.A sixth core from the Herald Arch contains lower Toarcian marine strata, indicated by biostratigraphy, truncated by a Neogene or younger unconformity. These Lower Jurassic strata evidently were deposited south of the arch, buried structurally to high levels of thermal maturity during the Early Cretaceous, and uplifted on the Herald thrust-fault system during the mid to Late Cretaceous. These interpretations are based on regional stratigraphy and apatite fission-track data reported in a complementary report and are corroborated by the presence of recycled palynomorphs of Early Jurassic age and high thermal maturity found in Upper Cretaceous strata in two of the foreland cores. This dataset provides evidence that uplift and exhumation of the Herald thrust belt provided sediment to the foreland during the Late Cretaceous.

Maxwell Strata and Cut Locus in the Sub-Riemannian Problem on the Engel Group

NASA Astrophysics Data System (ADS)

Ardentov, Andrei A.; Sachkov, Yuri L.

2017-12-01

We consider the nilpotent left-invariant sub-Riemannian structure on the Engel group. This structure gives a fundamental local approximation of a generic rank 2 sub-Riemannian structure on a 4-manifold near a generic point (in particular, of the kinematic models of a car with a trailer). On the other hand, this is the simplest sub-Riemannian structure of step three. We describe the global structure of the cut locus (the set of points where geodesics lose their global optimality), the Maxwell set (the set of points that admit more than one minimizer), and the intersection of the cut locus with the caustic (the set of conjugate points along all geodesics). The group of symmetries of the cut locus is described: it is generated by a one-parameter group of dilations R+ and a discrete group of reflections Z2 × Z2 × Z2. The cut locus admits a stratification with 6 three-dimensional strata, 12 two-dimensional strata, and 2 one-dimensional strata. Three-dimensional strata of the cut locus are Maxwell strata of multiplicity 2 (for each point there are 2 minimizers). Two-dimensional strata of the cut locus consist of conjugate points. Finally, one-dimensional strata are Maxwell strata of infinite multiplicity, they consist of conjugate points as well. Projections of sub-Riemannian geodesics to the 2-dimensional plane of the distribution are Euler elasticae. For each point of the cut locus, we describe the Euler elasticae corresponding to minimizers coming to this point. Finally, we describe the structure of the optimal synthesis, i. e., the set of minimizers for each terminal point in the Engel group.

Microbial secondary succession in soil microcosms of a desert oasis in the Cuatro Cienegas Basin, Mexico

PubMed Central

López-Lozano, Nguyen E.; Heidelberg, Karla B.; Nelson, William C.; García-Oliva, Felipe; Eguiarte, Luis E.

2013-01-01

Ecological succession is one of the most important concepts in ecology. However for microbial community succession, there is a lack of a solid theoretical framework regarding succession in microorganisms. This is in part due to microbial community complexity and plasticity but also because little is known about temporal patterns of microbial community shifts in different kinds of ecosystems, including arid soils. The Cuatro Cienegas Basin (CCB) in Coahuila, Mexico, is an arid zone with high diversity and endemisms that has recently been threatened by aquifer overexploitation. The gypsum-based soil system of the CCB is one of the most oligotrophic places in the world. We undertook a comparative 16S rRNA 454 pyrosequencing study to evaluate microbial community succession and recovery over a year after disturbance at two sites. Results were related to concurrent measurements of humidity, organic matter and total C and N content. While each site differed in both biogeochemistry and biodiversity, both present similar pattern of change at the beginning of the succession that diverged in later stages. After one year, experimentally disturbed soil was not similar to established and undisturbed adjacent soil communities indicating recovery and succession in disturbed soils is a long process. PMID:23638384

Identification of canopy strata in Allegheny hardwood stands

Treesearch

David W. McGill; Stephen B. Jones; Christopher A. Nowak

1995-01-01

Allegheny hardwood stands typically develop vertical canopy layers, or strata, due to differential species-specific growth rates and tolerance to shade. Across the Allegheny Plateau, black cherry dominates the main canopy, while sugar maple, American beech, and red maple are relegated to subcanopy strata.

New interpretation of the so-called Nubian strata in northeast Africa

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

Klitzsch, E.H.; Squyres, C.H.

1988-08-01

Stratigraphical interpretation of the so-called Nubian Sandstone of Egypt and northern Sudan have led to new ideas on the structural and paleogeographical development of northeast Africa. The strata formerly comprised under the term Nubian Sandstone include sediments from Cambrian to Paleocene age. Based on field work and paleontological investigations during the last 10 years, these strata can be subdivided into three major cycles, each characterizing a certain structural situation of northeast Africa. The first or Paleozoic cycle comprises strata of Cambrian to Early Carboniferous age. These strata were deposited during a period of generally northern dip of northeast Africa; continentalmore » sediments transported northward interfinger with marine strata resulting from southward transgressions. Sediments of the second cycle were deposited during and after Gondwana and northern continents collided, which caused updoming of large areas of Egypt and bordering areas to the west and east. As a result, most of Egypt became subject to erosion; transgressions remained near the present northern edge of the continent, and purely continental deposition took place in northern Sudan and bordering areas in Chad and Libya. The resulting strata are similar to the Karroo of East Africa. Strata of the third cycle were deposited after Pangea began to disintegrate. Northeast Africa now had a generally northern dip again, and consequently deposition was controlled - as during the first cycle - by northward drainage and southward transgressions. This last cycle began during Late Jurassic time.« less

Symbiont dynamics during ecosystem succession: co-occurring plant and arbuscular mycorrhizal fungal communities.

PubMed

García de León, David; Moora, Mari; Öpik, Maarja; Neuenkamp, Lena; Gerz, Maret; Jairus, Teele; Vasar, Martti; Bueno, C Guillermo; Davison, John; Zobel, Martin

2016-07-01

Although mycorrhizas are expected to play a key role in community assembly during ecological succession, little is known about the dynamics of the symbiotic partners in natural systems. For instance, it is unclear how efficiently plants and arbuscular mycorrhizal (AM) fungi disperse into early successional ecosystems, and which, if either, symbiotic partner drives successional dynamics. This study describes the dynamics of plant and AM fungal communities, assesses correlation in the composition of plant and AM fungal communities and compares dispersal limitation of plants and AM fungi during succession. We studied gravel pits 20 and 50 years post abandonment and undisturbed grasslands in Western Estonia. The composition of plant and AM fungal communities was strongly correlated, and the strength of the correlation remained unchanged as succession progressed, indicating a stable dependence among mycorrhizal plants and AM fungi. A relatively high proportion of the AM fungal taxon pool was present in early successional sites, in comparison with the respective fraction of plants. These results suggest that AM fungi arrived faster than plants and may thus drive vegetation dynamics along secondary vegetation succession. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

MEASUREMENT OF EFFECTIVE AIR DIFFUSION COEFFICIENTS FOR TRICHLOROETHENE IN UNDISTURBED SOIL CORES. (R826162)

EPA Science Inventory

Abstract

In this study, we measure effective diffusion coefficients for trichloroethene in undisturbed soil samples taken from Picatinny Arsenal, New Jersey. The measured effective diffusion coefficients ranged from 0.0053 to 0.0609 cm²/s over a range of air...

Dust emissions from undisturbed and disturbed, crusted playa surfaces: cattle trampling effects

USDA-ARS?s Scientific Manuscript database

Dry playa lake beds can be significant sources of fine dust emission. This study used a portable field wind tunnel to quantify the PM10 emissions from a bare, fine-textured playa surface located in the far northern Chihuahua Desert. The natural, undisturbed crust and its subjection to two levels of ...

Spatial autocorrelation in growth of undisturbed natural pine stands across Georgia

Treesearch

Raymond L. Czaplewski; Robin M. Reich; William A. Bechtold

1994-01-01

Moran's I statistic measures the spatial autocorrelation in a random variable measured at discrete locations in space. Permutation procedures test the null hypothesis that the observed Moran's I value is no greater than that expected by chance. The spatial autocorrelation of gross basal area increment is analyzed for undisturbed, naturally regenerated stands...

Undisturbed soil columns for lysimetry II. Miscible displacement and field evaluation

USDA-ARS?s Scientific Manuscript database

Concerns about agriculture's effect on water quality and the expanding use of no-tillage, has produced a crucial need for in situ solute transport research of mobile nutrients as affected by tillage system. Eight undisturbed soil columns (41 cm diameter by 100 cm long) were sealed into PVC cylinder...

Effect of in-situ disturbance within the soil mass on the stress-strain behaviour of silty soil

NASA Astrophysics Data System (ADS)

Noor, Sarah T.; Rabika Rahman, SS; Nahar, Sabiqun

2018-04-01

To date, different techniques have been evolved to collect soil in undisturbed condition so that the in-situ soil behaviour can be determined by carrying out laboratory tests. For the same reason, the execution of undisturbed soil sampling in practice is given a lot of efforts. However, this study brings the fact into consideration that the in-situ soil condition may not remain constant, rather it might vary time to time, because of different internal or external reasons. For example, the internal stress state of soil layers, existing below or above the swelling soil layer, become modified during shrinking and swelling resulting from drying and wetting of swelling clay, respectively. Further, foundations of building may transfer cyclic loads (generated by vibration installed in the building) to the soil below the foundation. Therefore, this study investigates the effects of stress-strain behaviour due to the disturbances on the shear strength of the soil with respect to that of undisturbed specimens. The shear strength of disturbed soil shows deviation from that of undisturbed specimen depending on the different parameters defining the severity of disturbance.

A comparative analysis of microbiomes in natural and anthropogenically disturbed soils of northwestern Kazakhstan

NASA Astrophysics Data System (ADS)

Pershina, E. V.; Ivanova, E. A.; Nagieva, A. G.; Zhiengaliev, A. T.; Chirak, E. L.; Andronov, E. E.; Sergaliev, N. Kh.

2016-06-01

The goal of this study was to determine the relationships between the structure of the soil microbiome and the agroecological state of soils by the example of natural undisturbed (steppe areas) and anthropogenically disturbed (pastures, croplands, fallows) areas in the territory of northwestern Kazakhstan. The highest abundance of proteobacteria was found in the anthropogenically disturbed of fallows and in undisturbed soils; in other cases, actinobacteria and representatives of the Firmicutes phylum predominated. Different kinds of anthropogenic impacts resulted in the decrease in the portions of bacteria from the Acidobacteria, Gemmatimonadetes, and Firmicutes phyla. In the disturbed soils, the portions of bacteria from the Erysipelothrix, Mycobacterium, Methylibium, Skermanella, Ralstonia, Lactococcus, Bdellovibrio, Candidatus nitrososphaera, Catellatospora, Cellulomonas, Stenotrophomonas, and Steroidobacter genera increased. Bacteria of the Erysipelothrix and Methylibium genera occurred only in the undisturbed soils. The anthropogenically disturbed and undisturbed soils differed significantly in the taxonomic structure of their microbiomes forming two separate clusters, which confirms the efficiency of using the data on the structure of soil microbiomes when assessing the agroecological status of soils.

Veterinarians and the animal-health industry: a complex dimension of opportunity.

PubMed

Sibbel, R L Rick

2006-01-01

The animal-health industry continues to offer many different opportunities for veterinarians interested in business applications for products and ideas vested in animal health and animal husbandry. These opportunities are expanding rapidly and becoming more diverse every day. Successful animal-health companies are increasing the recruiting and retention of business-savvy veterinary professionals. Employment earnings and broad offerings of employment extras in the animal health industries are in the top strata of the many veterinary professional options.

Mesozoic black shales, source mixing and carbon isotopes

NASA Astrophysics Data System (ADS)

Suan, Guillaume

2016-04-01

Over the last decades, considerable attention has been devoted to the paleoenvironmental and biogeochemical significance of Mesozoic black shales. Black shale-bearing successions indeed often display marked changes in the organic carbon isotope composition (δ13Corg), which have been commonly interpreted as evidence for dramatic perturbations of global carbon budgets and CO2 levels. Arguably the majority of these studies have discarded some more "local" explanations when interpreting δ13Corg profiles, most often because comparable profiles occur on geographically large and distant areas. Based on newly acquired data and selected examples from the literature, I will show that the changing contribution of organic components with distinct δ13C signatures exerts a major but overlooked influence of Mesozoic δ13Corg profiles. Such a bias occurs across a wide spectrum of sedimentological settings and ages, as shown by the good correlation between δ13Corg values and proxies of kerogen proportions (such as rock-eval, biomarker, palynofacies and palynological data) recorded in Mesozoic marginal to deep marine successions of Triassic, Jurassic and Cretaceous age. In most of these successions, labile, 12C-enriched amorphous organic matter of marine origin dominates strata deposited under anoxic conditions, while oxidation-resistant, 13C-rich terrestrial particles dominate strata deposited under well-oxygenated conditions. This influence is further illustrated by weathering profiles of Toarcian (Lower Jurassic) black shales from France, where weathered areas dominated by refractory organic matter show dramatic 13C-enrichment (and decreased total organic carbon and pyrite contents) compared to non-weathered portions of the same horizon. The implications of these results for chemostratigraphic correlations and pCO2 reconstructions of Mesozoic will be discussed, as well as strategies to overcome this major bias.

Evolution of the Early Triassic marine depositional environment in the Croatian Dinarides

NASA Astrophysics Data System (ADS)

Aljinović, Dunja; Smirčić, Duje; Horacek, Micha; Richoz, Sylvain; Krystyn, Leopold; Kolar-Jurkovšek, Tea; Jurkovšek, Bogdan

2014-05-01

In the central part of the Dinarides in Croatia, the Early Triassic depositional sequence was investigated by means of litho-, bio- and chemostratigraphy at locality Plavno (ca. 1.000m thick). Conodont and δ13C-isotope analysis were a powerfull tool to determine stage and substage boundaries. The succession begins with the second conodont zone of the Griesbachian Isarcicella staeschei and I. isarcica with low δ13C-values and a steadily increase towards the Griesbachian-Dienerian boundary. Around that boundary a minor, short, negative excursion occurs. In the Dienerian the δ13C-values increase with a steepening of the slope towards the Dienerian-Smithian boundary. Around that boundary a maximum of +5o in shallow water carbonate occurs followed by a steep and continuous drop to low, often negative values in the Smithian. Just before the Smithian-Spathian boundary a steep rise to a second maximum is documented. It is followed by decline in the Spathian and a gentle increase to a rounded peak at the Spathian-Anisian boundary. In lithological sense Plavno succession has threefold division: 1) carbonates representing the oldest Early Triassic strata (early Griesbachian); 2) dominantly red clastics (shales, siltstones and sandstones) with intercalation of oncoid/ooid or bioclast rich grainstones (uppermost Griesbachian, Dienerian and Smithian) and 3) dominantly grey carbonaceous lime mudstones, marls and calcisiltites with ammonoids representing Spathian strata. In the oldest strata (Griesbachian) in macrocrystalline subhedral dolomites rare microspheres and foraminifers Earlandia and Cornuspira point to the stressful conditions related to the end Permian mass extinction. In the uppermost Griesbachian and Dienerian strata, within dominantly clastic deposition, rare coarse oncoliths with typical microbial cortices occur. Their presence fits to the interpretation of biotical-induced precipitation related to PTB extinction and can suggest still stressful condition. The Dienerian and Smithian are characterized by strong siliciclastic input and deposition of red shales, siltstones and sandstones with intercalation of oolithic and bioclastic grainstones. Hummocky-cross-strata witness the importance of storms. Presence of loadcasts and abundant casts of bivalve shells suggest quick deposition of terrigenous material and instant burying of epifauna during storms. Abundant trace fossils preserved in shales evidence intensive life activity in an overall shallow depositonal environment. During the Spathian deposition of lime mudstones and marls prevails. Two Spathian intervals bear ammonoid fauna suggest deposition in slightly deeper environment and a connection with the open sea testifying a transgression at the beginning of Spathian. Even in deeper environment storms play a significant role assuming deposition above storm wave base. The influence of storms in this deeper environment is recognized as accumulation of coarsegrained bioclastic lag at the base of storm beds, graded calcisiltites, gutter casts and hummocky-cross-stratified beds. Intense bioturbation suggest colonization by organisms between storms. Pending from nature and distribution of facies the Plavno sequence has been interpreted as epeiric ramp. An epeiric ramp is defined here as having a very low bathymetric slope (negligible in its inner regions), no grainy shoreface facies, water depths of tens of meters, a width of many hundreds of kilometers and depositional processes dominated by storms.

Pollen dispersal of tropical trees (Dinizia excelsa: Fabaceae) by native insects and African honeybees in pristine and fragmented Amazonian rainforest.

PubMed

Dick, Christopher W; Etchelecu, Gabriela; Austerlitz, Frédéric

2003-03-01

Tropical rainforest trees typically occur in low population densities and rely on animals for cross-pollination. It is of conservation interest therefore to understand how rainforest fragmentation may alter the pollination and breeding structure of remnant trees. Previous studies of the Amazonian tree Dinizia excelsa (Fabaceae) found African honeybees (Apis mellifera scutellata) as the predominant pollinators of trees in highly disturbed habitats, transporting pollen up to 3.2 km between pasture trees. Here, using microsatellite genotypes of seed arrays, we compare outcrossing rates and pollen dispersal distances of (i) remnant D. excelsa in three large ranches, and (ii) a population in undisturbed forest in which African honeybees were absent. Self-fertilization was more frequent in the disturbed habitats (14%, n = 277 seeds from 12 mothers) than in undisturbed forest (10%, n = 295 seeds from 13 mothers). Pollen dispersal was extensive in all three ranches compared to undisturbed forest, however. Using a twogener analysis, we estimated a mean pollen dispersal distance of 1509 m in Colosso ranch, assuming an exponential dispersal function, and 212 m in undisturbed forest. The low effective density of D. excelsa in undisturbed forest (approximately 0.1 trees/ha) indicates that large areas of rainforest must be preserved to maintain minimum viable populations. Our results also suggest, however, that in highly disturbed habitats Apis mellifera may expand genetic neighbourhood areas, thereby linking fragmented and continuous forest populations.

Measurement of undisturbed di-nitrogen emissions from aquatic ecosystems

NASA Astrophysics Data System (ADS)

Qin, Shuping, Clough, Timothy, Lou, Jiafa; Hu, Chunsheng; Oenema, Oene; Wrage-Mönnig, Nicole; Zhang, Yuming

2016-04-01

Increased production of reactive nitrogen (Nr) from atmospheric di-nitrogen (N2) during the last century has greatly contributed to increased food production1-4. However, enriching the biosphere with Nr through N fertilizer production, combustion, and biological N2 fixation has also caused a series of negative effects on global ecosystems 5,6, especially aquatic ecosystems7. The main pathway converting Nr back into the atmospheric N2 pool is the last step of the denitrification process, i.e., the reduction of nitrous oxide (N2O) into N2 by micro-organisms7,8. Despite several attempts9,10, there is not yet an accurate, fast and direct method for measuring undisturbed N2 fluxes from denitrification in aquatic sediments at the field scale11-14. Such a method is essential to study the feedback of aquatic ecosystems to Nr inputs1,2,7. Here we show that the measurement of both N2O emission and its isotope signature can be used to infer the undisturbed N2 fluxes from aquatic ecosystems. The microbial reduction of N2O increases the natural abundance of 15N-N2O relative to 14N-N2O (δ15N-N2O). We observed linear relationships between δ15N-N2O and the logarithmic transformed N2O/(N2+N2O) emission ratios. Through independent measurements, we verified that the undisturbed N2 flux from aquatic ecosystems can be inferred from measurements of N2O emissions and the δ15N-N2O signature. Our method allows the determination of field-scale N2 fluxes from undisturbed aquatic ecosystems, and thereby allows model predictions of denitrification rates to be tested. The undisturbed N2 fluxes observed are almost one order of magnitude higher than those estimated by the traditional method, where perturbation of the system occurs, indicating that the ability of aquatic ecosystems to remove Nr may have been severely underestimated.

Assessing the Impact of Deforestation of the Atlantic Rainforest on Ant-Fruit Interactions: A Field Experiment Using Synthetic Fruits

PubMed Central

Bieber, Ana Gabriela D.; Silva, Paulo S. D.; Sendoya, Sebastián F.; Oliveira, Paulo S.

2014-01-01

Ants frequently interact with fleshy fruits on the ground of tropical forests. This interaction is regarded as mutualistic because seeds benefit from enhanced germination and dispersal to nutrient-rich microsites, whereas ants benefit from consuming the nutritious pulp/aril. Considering that the process of deforestation affects many attributes of the ecosystem such as species abundance and composition, and interspecific interactions, we asked whether the interaction between ants and fallen fleshy fruits in the Brazilian Atlantic forest differs between human-created fragments and undisturbed forests. We controlled diaspore type and quantity by using synthetic fruits (a plastic ‘seed’ covered by a lipid-rich ‘pulp’), which were comparable to lipid-rich fruits. Eight independent areas (four undisturbed forests, and four disturbed forest fragments) were used in the field experiment, in which we recorded the attracted ant species, ant behaviour, and fruit removal distance. Fruits in undisturbed forest sites attracted a higher number of species than those in disturbed forests. Moreover, the occurrence of large, fruit-carrying ponerine ants (Pachycondyla, Odontomachus; 1.1 to 1.4 cm) was higher in undisturbed forests. Large species (≥3 mm) of Pheidole (Myrmicinae), also able to remove fruits, did not differ between forest types. Following these changes in species occurrence, fruit displacement was more frequent in undisturbed than in disturbed forests. Moreover, displacement distances were also greater in the undisturbed forests. Our data suggest that fallen fleshy fruits interacting with ants face different fates depending on the conservation status of the forest. Together with the severe loss of their primary dispersers in human-disturbed tropical forest sites, vertebrate-dispersed fruits may also be deprived of potential ant-derived benefits in these habitats due to shifts in the composition of interacting ant species. Our data illustrate the use of synthetic fruits to better understand the ecology of ant-fruit interactions in variable ecological settings, including human-disturbed landscapes. PMID:24587341

Assessing the impact of deforestation of the Atlantic rainforest on ant-fruit interactions: a field experiment using synthetic fruits.

PubMed

Bieber, Ana Gabriela D; Silva, Paulo S D; Sendoya, Sebastián F; Oliveira, Paulo S

2014-01-01

Ants frequently interact with fleshy fruits on the ground of tropical forests. This interaction is regarded as mutualistic because seeds benefit from enhanced germination and dispersal to nutrient-rich microsites, whereas ants benefit from consuming the nutritious pulp/aril. Considering that the process of deforestation affects many attributes of the ecosystem such as species abundance and composition, and interspecific interactions, we asked whether the interaction between ants and fallen fleshy fruits in the Brazilian Atlantic forest differs between human-created fragments and undisturbed forests. We controlled diaspore type and quantity by using synthetic fruits (a plastic 'seed' covered by a lipid-rich 'pulp'), which were comparable to lipid-rich fruits. Eight independent areas (four undisturbed forests, and four disturbed forest fragments) were used in the field experiment, in which we recorded the attracted ant species, ant behaviour, and fruit removal distance. Fruits in undisturbed forest sites attracted a higher number of species than those in disturbed forests. Moreover, the occurrence of large, fruit-carrying ponerine ants (Pachycondyla, Odontomachus; 1.1 to 1.4 cm) was higher in undisturbed forests. Large species (≥3 mm) of Pheidole (Myrmicinae), also able to remove fruits, did not differ between forest types. Following these changes in species occurrence, fruit displacement was more frequent in undisturbed than in disturbed forests. Moreover, displacement distances were also greater in the undisturbed forests. Our data suggest that fallen fleshy fruits interacting with ants face different fates depending on the conservation status of the forest. Together with the severe loss of their primary dispersers in human-disturbed tropical forest sites, vertebrate-dispersed fruits may also be deprived of potential ant-derived benefits in these habitats due to shifts in the composition of interacting ant species. Our data illustrate the use of synthetic fruits to better understand the ecology of ant-fruit interactions in variable ecological settings, including human-disturbed landscapes.

The importance of the riparian zone and in-stream processes in nitrate attenuation in undisturbed and agricultural watersheds – a review of the scientific literature

USGS Publications Warehouse

Ranalli, Anthony J.; Macalady, Donald L.

2010-01-01

We reviewed published studies from primarily glaciated regions in the United States, Canada, and Europe of the (1) transport of nitrate from terrestrial ecosystems to aquatic ecosystems, (2) attenuation of nitrate in the riparian zone of undisturbed and agricultural watersheds, (3) processes contributing to nitrate attenuation in riparian zones, (4) variation in the attenuation of nitrate in the riparian zone, and (5) importance of in-stream and hyporheic processes for nitrate attenuation in the stream channel. Our objectives were to synthesize the results of these studies and suggest methodologies to (1) monitor regional trends in nitrate concentration in undisturbed 1st order watersheds and (2) reduce nitrate loads in streams draining agricultural watersheds. Our review reveals that undisturbed headwater watersheds have been shown to be very retentive of nitrogen, but the importance of biogeochemical and hydrological riparian zone processes in retaining nitrogen in these watersheds has not been demonstrated as it has for agricultural watersheds. An understanding of the role of the riparian zone in nitrate attenuation in undisturbed watersheds is crucial because these watersheds are increasingly subject to stressors, such as changes in land use and climate, wildfire, and increases in atmospheric nitrogen deposition. In general, understanding processes controlling the concentration and flux of nitrate is critical to identifying and mapping the vulnerability of watersheds to water quality changes due to a variety of stressors. In undisturbed and agricultural watersheds we propose that understanding the importance of riparian zone processes in 2nd order and larger watersheds is critical. Research is needed that addresses the relative importance of how the following sources of nitrate along any given stream reach might change as watersheds increase in size and with flow: (1) inputs upstream from the reach, (2) tributary inflow, (3) water derived from the riparian zone, (4) groundwater from outside the riparian zone (intermediate or regional sources), and (5) in-stream (hyporheic) processes.

The Strata-1 experiment on small body regolith segregation

NASA Astrophysics Data System (ADS)

Fries, Marc; Abell, Paul; Brisset, Julie; Britt, Daniel; Colwell, Joshua; Dove, Adrienne; Durda, Dan; Graham, Lee; Hartzell, Christine; Hrovat, Kenneth; John, Kristen; Karrer, Dakotah; Leonard, Matthew; Love, Stanley; Morgan, Joseph; Poppin, Jayme; Rodriguez, Vincent; Sánchez-Lana, Paul; Scheeres, Dan; Whizin, Akbar

2018-01-01

The Strata-1 experiment studies the mixing and segregation dynamics of regolith on small bodies by exposing a suite of regolith simulants to the microgravity environment aboard the International Space Station (ISS) for one year. This will improve our understanding of regolith dynamics and properties on small asteroids, and may assist in interpreting analyses of samples from missions to small bodies such as OSIRIS-REx, Hayabusa-1 and -2, and future missions to small bodies. The Strata-1 experiment consists of four evacuated tubes partially filled with regolith simulants. The simulants are chosen to represent models of regolith covering a range of complexity and tailored to inform and improve computational studies. The four tubes are regularly imaged while moving in response to the ambient vibrational environment using dedicated cameras. The imagery is then downlinked to the Strata-1 science team about every two months. Analyses performed on the imagery includes evaluating the extent of the segregation of Strata-1 samples and comparing the observations to computational models. After Strata-1's return to Earth, x-ray tomography and optical microscopy will be used to study the post-flight simulant distribution. Strata-1 is also a pathfinder for the new "1E" ISS payload class, which is intended to simplify and accelerate emplacement of experiments on board ISS.

High latitude minor ion enhancements: A clue for studies of magnetosphere-atmosphere coupling. [using OGO 6 ion mass spectrometer

NASA Technical Reports Server (NTRS)

Taylor, H. A., Jr.

1973-01-01

Unexpectedly abrupt and pronounced distributions of the thermal molecular ions NO(+), O2(+) and N2(+) were observed at mid and high latitudes by the OGO-6 ion mass spectrometer. These minor ions may reach concentration levels exceeding 1000 ions/cu cm at altitudes as great as 1000 km, suggestive of scale heights well in excess of those inferred from low and mid-latitude measurements, under relatively undisturbed conditions. The high latitude ion enhancements were observed to be narrowly defined in time and space, with molecular ion concentrations changing by as much as an order of magnitude between successive orbits.

Paleogeographic and paleo-oceanographic influences on carbon isotope signatures: Implications for global and regional correlation, Middle-Upper Jurassic of Saudi Arabia

NASA Astrophysics Data System (ADS)

Eltom, Hassan A.; Gonzalez, Luis A.; Hasiotis, Stephen T.; Rankey, Eugene C.; Cantrell, Dave L.

2018-02-01

Carbon isotope data (δ13C) can provide an essential means for refining paleogeographic and paleo-oceanographic reconstructions, and interpreting stratigraphic architecture within complex carbonate strata. Although the primary controls on global δ13C signatures of marine carbonates are well understood, understanding their latitudinal and regional variability is poor. To better constrain the nature and applications of δ13C stratigraphy, this study: 1) presents a new high-resolution δ13C stratigraphic curve from Middle to Upper Jurassic carbonates in the upper Tuwaiq Mountain, Hanifa, and lower Jubaila formations in central Saudi Arabia; 2) explores their latitudinal and regional variability; and 3) discusses their implications for stratigraphic correlations. Analysis of δ13C data identified six mappable units with distinct δ13C signatures (units 1-6) between up-dip and down-dip sections, and one unit (unit 7) that occurs only in the down-dip section of the study succession. δ13C data from the upper Tuwaiq Mountain Formation and the lower Hanifa Formation (units 1, 2), which represent Upper Callovian to Middle Oxfordian strata, and record two broad positive δ13C excursions. In the upper part of the Hanifa Formation (units 3-6, Early Oxfordian-Late Kimmeridgian), δ13C values decreased upward to unit 7, which showed a broad positive δ13C excursion. Isotopic data suggest similar δ13C trends between the southern margin of the Tethys Ocean (Arabian Plate; low latitude, represented by the study succession) and northern Tethys oceans (high latitude), despite variations in paleoclimatic, paleogeographic, and paleoceanographic conditions. Variations in the δ13C signal in this succession can be attributed to the burial of organic matter and marine circulation at the time of deposition. Our study uses δ13C signatures to provide independent data for chronostratigraphic constraints which help in stratigraphic correlations within heterogeneous carbonate successions.

Carbon dioxide exchange between an undisturbed old-growth temperate forest and the atmosphere

Treesearch

D.Y. Hollinger; F.M. Kelliher; J.N. Byers; J.E. Hunt; T.M. McSeveny; P.L. Weir

1994-01-01

We used the eddy-correlation technique to investigate the exchange of C02 between an undisturbed old-growth forest and the atmosphere at a remote Southern Hemisphere site on 15 d between 1989 and 1990. Our goal was to determine how environmental factors regulate ecosystem CO2 exchange, and to test whether present knowledge...

Spatial cross-correlation of undisturbed, natural shortleaf pine stands in northern Georgia

Treesearch

Robin M. Reich; Raymond L. Czaplewski; William A. Bechtold

1994-01-01

In this study a cross-correlation statistic is used to analyse the spatial relationship among stand characteristics of natural, undisturbed shortleaf pine stands sampled during 1961-72 and 1972-82 in northern Georgia. Stand characteristics included stand age, site index, tree density, hardwood competition, and mortality. In each time period, the spatial cross-...

Fuels on disturbed and undisturbed sites in the southern Appalachian Mountains, USA

Treesearch

Thomas A. Waldrop; Lucy Brudnak; Sandra Rideout-Hanzak

2007-01-01

Fuel distribution in the southern Appalachian Mountain region was measured in over 1000 study plots that were stratified by topographic position (aspect and slop position) and disturbance history. Few fuel differences occurred among topographic positions for undisturbed plots, indicating that fuel accumulation is no greater on highly productive sites than on less...

Water quality and streamflow in the Caribou-Poker Creeks Research Watershed, central Alaska, 1978.

Treesearch

Jerry W. Hilgert; Charles W. Slaughter

1983-01-01

Baseline data from 1978 are presented on precipitation, streamflow, and chemical and biological water quality in a subarctic, taiga watershed. First-, second-, and third-order streams that drain undisturbed catchments embracing permafrost-underlain and permafrost-free landscapes were monitored; results are being used in analysis of the natural, undisturbed condition of...

Ancient Martian aeolian processes and palaeomorphology reconstructed from the Stimson formation on the lower slope of Aeolis Mons, Gale crater, Mars

USGS Publications Warehouse

Banham, Steve G.; Gupta, Sanjeev; Rubin, David M.; Watkins, Jessica A.; Sumner, Dawn Y.; Edgett, Kenneth S.; Grotzinger, John P.; Lewis, Kevin W.; Edgar, Lauren; Stack, Kathryn M.; Barnes, Robert; Bell, Jame F. III; Day, Mackenzie D.; Ewing, Ryan C.; Lapotre, Mathieu G.A.; Stein, Nathan T.; Rivera-Hernandez, Frances; Vasavada, Ashwin R.

2018-01-01

Reconstruction of the palaeoenvironmental context of Martian sedimentary rocks is central to studies of ancient Martian habitability and regional palaeoclimate history. This paper reports the analysis of a distinct aeolian deposit preserved in Gale crater, Mars, and evaluates its palaeomorphology, the processes responsible for its deposition, and its implications for Gale crater geological history and regional palaeoclimate. Whilst exploring the sedimentary succession cropping out on the northern flank of Aeolis Mons, Gale crater, the Mars Science Laboratory rover Curiosity encountered a decametre‐thick sandstone succession, named the Stimson formation, unconformably overlying lacustrine deposits of the Murray formation. The sandstone contains sand grains characterized by high roundness and sphericity, and cross‐bedding on the order of 1 m in thickness, separated by sub‐horizontal bounding surfaces traceable for tens of metres across outcrops. The cross‐beds are composed of uniform thickness cross‐laminations interpreted as wind‐ripple strata. Cross‐sets are separated by sub‐horizontal bounding surfaces traceable for tens of metres across outcrops that are interpreted as dune migration surfaces. Grain characteristics and presence of wind‐ripple strata indicate deposition of the Stimson formation by aeolian processes. The absence of features characteristic of damp or wet aeolian sediment accumulation indicate deposition in a dry aeolian system. Reconstruction of the palaeogeomorphology suggests that the Stimson dune field was composed largely of simple sinuous crescentic dunes with a height of ca10 m, and wavelengths of ca 150 m, with local development of complex dunes. Analysis of cross‐strata dip‐azimuths indicates that the general dune migration direction and hence net sediment transport was towards the north‐east. The juxtaposition of a dry aeolian system unconformably above the lacustrine Murray formation represents starkly contrasting palaeoenvironmental and palaeoclimatic conditions. Stratigraphic relationships indicate that this transition records a significant break in time, with the Stimson formation being deposited after the Murray formation and stratigraphically higher Mount Sharp group rocks had been buried, lithified and subsequently eroded.

Disturbance and Plant Succession in the Mojave and Sonoran Deserts of the American Southwest

PubMed Central

Abella, Scott R.

2010-01-01

Disturbances such as fire, land clearing, and road building remove vegetation and can have major influences on public health through effects on air quality, aesthetics, recreational opportunities, natural resource availability, and economics. Plant recovery and succession following disturbance are poorly understood in arid lands relative to more temperate regions. This study quantitatively reviewed vegetation reestablishment following a variety of disturbances in the Mojave and Sonoran Deserts of southwestern North America. A total of 47 studies met inclusion criteria for the review. The time estimated by 29 individual studies for full reestablishment of total perennial plant cover was 76 years. Although long, this time was shorter than an estimated 215 years (among 31 individual studies) required for the recovery of species composition typical of undisturbed areas, assuming that recovery remains linear following the longest time since disturbance measurement made by the studies. PMID:20617030

Controls on architecture of Argentine limestone and associated strata in northeastern Kansas. A firstcut method for evaluating limestone aggregate durability using spectral scintillometry

DOT National Transportation Integrated Search

2006-10-01

Missourian strata were studied in eastern Kansas to evaluate the build-and-fill controls on strata deposited in association with high-amplitude glacioeustatic sea-level fluctuations. Results from this study show that creation of relief in high-freque...

Ice sheet load cycling and fluid underpressures in the Eastern Michigan Basin, Ontario, Canada

USGS Publications Warehouse

Neuzil, Christopher E.; Provost, Alden M.

2014-01-01

Strong fluid underpressures have been detected in Paleozoic strata in the eastern Michigan Basin, with hydraulic heads reaching ~400 m below land surface (~4 MPa underpressure) and ~200 m below sea level in strata where unusually low permeabilities (~10−20–10−23 m2) were measured in situ. Multiple glaciations, including three with as much as 3 km of ice cover at the site in the last 120 ka, suggest a causal link with the underpressures. We examined this possibility using a one-dimensional groundwater flow model incorporating mechanical loading from both ice weight and lithospheric flexure. Because hydrologic and mechanical changes during glaciation are not well characterized and subsurface properties are imperfectly known, the model was used inversely to estimate flexural loads and loosely constrained permeabilities by matching observed pressures. Acceptable matches were obtained for a surprisingly wide range of scenarios with permeabilities close to measured values and plausible flexural loads. Matches were not obtained when too many parameters were preselected, or when permeabilities were constrained to be significantly larger than measured values. In successful model runs groundwater expulsion under glacial-mechanical loads caused the underpressuring, and flexural loads were important if aquifer and sub-glacial pressures were significantly elevated during glaciation. Simulated fluid pressures in the low-permeability strata fluctuated by 30–40 MPa during glacial cycles but resulted in advective transport of only tens of meters or less. Although other mechanisms cannot be ruled out, we conclude that glacial-mechanical forcing of a water-saturated system can explain the observed underpressures.

Structural deformation at the Flynn Creek impact crater, Tennessee - A preliminary report on deep drilling

NASA Technical Reports Server (NTRS)

Roddy, D. J.

1979-01-01

The geologic and core drilling studies described in the present paper show that the Flynn Creek crater has such distinctive morphological features as a broad flat hummocky floor; large central peak; locally terraced crater walls; uplifted, as well as flat-lying rim segments; and a surrounding ejecta blanket. The major structural features include a shallow depth of total brecciation and excavation as compared with apparent crater diameter; a thin breccia lens underlain by a thin zone of disrupted strata; concentric ring fault zones in inner rim, beneath crater wall, and outer crater floor regions; a large central uplift underlain by a narrow dipping zone of deeply disrupted strata; faulted, folded, brecciated, and fractured rim strata; and uplifted rim strata, which dip away from the crater, and flat-lying rim strata, which terminate as inward dipping rocks.

Model for the prediction of subsurface strata movement due to underground mining

NASA Astrophysics Data System (ADS)

Cheng, Jianwei; Liu, Fangyuan; Li, Siyuan

2017-12-01

The problem of ground control stability due to large underground mining operations is often associated with large movements and deformations of strata. It is a complicated problem, and can induce severe safety or environmental hazards either at the surface or in strata. Hence, knowing the subsurface strata movement characteristics, and making any subsidence predictions in advance, are desirable for mining engineers to estimate any damage likely to affect the ground surface or subsurface strata. Based on previous research findings, this paper broadly applies a surface subsidence prediction model based on the influence function method to subsurface strata, in order to predict subsurface stratum movement. A step-wise prediction model is proposed, to investigate the movement of underground strata. The model involves a dynamic iteration calculation process to derive the movements and deformations for each stratum layer; modifications to the influence method function are also made for more precise calculations. The critical subsidence parameters, incorporating stratum mechanical properties and the spatial relationship of interest at the mining level, are thoroughly considered, with the purpose of improving the reliability of input parameters. Such research efforts can be very helpful to mining engineers’ understanding of the moving behavior of all strata over underground excavations, and assist in making any damage mitigation plan. In order to check the reliability of the model, two methods are carried out and cross-validation applied. One is to use a borehole TV monitor recording to identify the progress of subsurface stratum bedding and caving in a coal mine, the other is to conduct physical modelling of the subsidence in underground strata. The results of these two methods are used to compare with theoretical results calculated by the proposed mathematical model. The testing results agree well with each other, and the acceptable accuracy and reliability of the proposed prediction model are thus validated.

Soil-foraging animals alter the composition and co-occurrence of microbial communities in a desert shrubland

PubMed Central

Eldridge, David J; Woodhouse, Jason N; Curlevski, Nathalie J A; Hayward, Matthew; Brown, Mark V; Neilan, Brett A

2015-01-01

Animals that modify their physical environment by foraging in the soil can have dramatic effects on ecosystem functions and processes. We compared bacterial and fungal communities in the foraging pits created by bilbies and burrowing bettongs with undisturbed surface soils dominated by biocrusts. Bacterial communities were characterized by Actinobacteria and Alphaproteobacteria, and fungal communities by Lecanoromycetes and Archaeosporomycetes. The composition of bacterial or fungal communities was not observed to vary between loamy or sandy soils. There were no differences in richness of either bacterial or fungal operational taxonomic units (OTUs) in the soil of young or old foraging pits, or undisturbed soils. Although the bacterial assemblage did not vary among the three microsites, the composition of fungi in undisturbed soils was significantly different from that in old or young foraging pits. Network analysis indicated that a greater number of correlations between bacterial OTUs occurred in undisturbed soils and old pits, whereas a greater number of correlations between fungal OTUs occurred in undisturbed soils. Our study suggests that digging by soil-disturbing animals is likely to create successional shifts in soil microbial and fungal communities, leading to functional shifts associated with the decomposition of organic matter and the fixation of nitrogen. Given the primacy of organic matter decomposition in arid and semi-arid environments, the loss of native soil-foraging animals is likely to impair the ability of these systems to maintain key ecosystem processes such as the mineralization of nitrogen and the breakdown of organic matter, and to recover from disturbance. PMID:25932616

Field application of a planted fixed bed reactor (PFR) for support media and rhizosphere investigation using undisturbed samples from full-scale constructed wetlands.

PubMed

Barreto, A B; Vasconcellos, G R; von Sperling, M; Kuschk, P; Kappelmeyer, U; Vasel, J L

2015-01-01

This study presents a novel method for investigations on undisturbed samples from full-scale horizontal subsurface-flow constructed wetlands (HSSFCW). The planted fixed bed reactor (PFR), developed at the Helmholtz Center for Environmental Research (UFZ), is a universal test unit for planted soil filters that reproduces the operational conditions of a constructed wetland (CW) system in laboratory scale. The present research proposes modifications on the PFR original configuration in order to allow its operation in field conditions. A mobile device to obtain undisturbed samples from real-scale HSSFCW was also developed. The experimental setting is presented with two possible operational configurations. The first allows the removal and replacement of undisturbed samples in the CW bed for laboratory investigations, guaranteeing sample integrity with a mobile device. The second allows the continuous operation of the PFR and undisturbed samples as a fraction of the support media, reproducing the same environmental conditions outside the real-scale system. Investigations on the hydrodynamics of the adapted PFR were carried out with saline tracer tests, validating the proposed adaptation. Six adapted PFR units were installed next to full-scale HSSFCW beds and fed with interstitial liquid pumped from two regions of planted and unplanted support media. Fourteen points were monitored along the system, covering carbon fractions, nitrogen and sulfate. The results indicate the method as a promising tool for investigations on CW support media, rhizosphere and open space for studies on CW modeling, respirometry, kinetic parameters, microbial communities, redox potential and plant influence on HSSFCW.

PIRLS 2011 User Guide for the International Database. Supplement 4: PIRLS 2011 Sampling Stratification Information

ERIC Educational Resources Information Center

Foy, Pierre, Ed.; Drucker, Kathleen T., Ed.

2013-01-01

This supplement contains documentation on the explicit and implicit stratification variables included in the PIRLS 2011 data files. The explicit strata are smaller sampling frames, created from the national sampling frames, from which national samples of schools were drawn. The implicit strata are nested within the explicit strata, and were used…

Post-stratified estimation: with-in strata and total sample size recommendations

Treesearch

James A. Westfall; Paul L. Patterson; John W. Coulston

2011-01-01

Post-stratification is used to reduce the variance of estimates of the mean. Because the stratification is not fixed in advance, within-strata sample sizes can be quite small. The survey statistics literature provides some guidance on minimum within-strata sample sizes; however, the recommendations and justifications are inconsistent and apply broadly for many...

TIMSS 2011 User Guide for the International Database. Supplement 4: TIMSS 2011 Sampling Stratification Information

ERIC Educational Resources Information Center

Foy, Pierre, Ed.; Arora, Alka, Ed.; Stanco, Gabrielle M., Ed.

2013-01-01

This supplement contains documentation on the explicit and implicit stratification variables included in the TIMSS 2011 data files. The explicit strata are smaller sampling frames, created from the national sampling frames, from which national samples of schools were drawn. The implicit strata are nested within the explicit strata, and were used…

Estimation of CO2 diffusion coefficient at 0-10 cm depth in undisturbed and tilled soils

USDA-ARS?s Scientific Manuscript database

Diffusion coefficients (D) of CO2 at 0 – 10 cm layers in undisturbed and tilled soil conditions were estimated using Penman, Millington-Quirk, Ridgwell et al. (1999), Troeh et al., and Moldrup et al. models. Soil bulk density and volumetric soil water content ('v) at 0 – 10 cm were measured on April...

Occurrence of an exotic earthworm (Amynthas agrestis) in undisturbed soils of the southern Appalachian Mountains, USA

Treesearch

Mac. A. Callaham; Paul F. Hendrix; Ross J. Phillips

2003-01-01

This study documents the occurrence of an aggressive invasive earthworm species in undisturbed forest soils of the southern Appalachian Mountains of northern Georgia, USA. Earthworms were sorted from samples collected in pitfall traps that had been set in mature, mesic oak-hickory forests in remote, high elevation, locations across northern Georgia. Specimens were...

Changes in soil hydraulic properties caused by construction of a simulated waste trench at the Idaho National Engineering Laboratory, Idaho

USGS Publications Warehouse

Shakofsky, S.M.

1995-01-01

In order to assess the effect of filled waste disposal trenches on transport-governing soil properties, comparisons were made between profiles of undisturbed soil and disturbed soil in a simulated waste trench. The changes in soil properties induced by the construction of a simulated waste trench were measured near the Radioactive Waste Management Complex at the Idaho National Engineering Laboratory (INEL) in the semi-arid southeast region of Idaho. The soil samples were collected, using a hydraulically- driven sampler to minimize sample disruption, from both a simulated waste trench and an undisturbed area nearby. Results show that the undisturbed profile has distinct layers whose properties differ significantly, whereas the soil profile in the simulated waste trench is. by comparison, homogeneous. Porosity was increased in the disturbed cores, and, correspondingly, saturated hydraulic conductivities were on average three times higher. With higher soil-moisture contents (greater than 0.32), unsaturated hydraulic conductivities for the undisturbed cores were typically greater than those for the disturbed cores. With lower moisture contents, most of the disturbed cores had greater hydraulic conductivities. The observed differences in hydraulic conductivities are interpreted and discussed as changes in the soil pore geometry.

Outcrops, Fossils, Geophysical Logs, and Tectonic Interpretations of the Upper Cretaceous Frontier Formation and Contiguous Strata in the Bighorn Basin, Wyoming and Montana

USGS Publications Warehouse

Merewether, E.A.; Cobban, W.A.; Tillman, R.W.

2010-01-01

In the Bighorn Basin of north-central Wyoming and south-central Montana, the Frontier Formation of early Late Cretaceous age consists of siliciclastic, bentonitic, and carbonaceous beds that were deposited in marine, brackish-water, and continental environments. Most lithologic units are laterally discontinuous. The Frontier Formation conformably overlies the Mowry Shale and is conformably overlain by the Cody Shale. Molluscan fossils collected from outcrops of these formations and listed in this report are mainly of marine origin and of Cenomanian, Turonian, and Coniacian ages. The lower and thicker part of the Frontier in the Bighorn Basin is of Cenomanian age and laterally equivalent to the Belle Fourche Member of the Frontier in central Wyoming. Near the west edge of the basin, these basal strata are disconformably overlain by middle Turonian beds that are the age equivalent of the Emigrant Gap Member of the Frontier in central Wyoming. The middle Turonian beds are disconformably overlain by lower Coniacian strata. Cenomanian strata along the south and east margins of the basin are disconformably overlain by upper Turonian beds in the upper part of the Frontier, as well as in the lower part of the Cody; these are, in turn, conformably overlain by lower Coniacian strata. Thicknesses and ages of Cenomanian strata in the Bighorn Basin and adjoining regions are evidence of regional differential erosion and the presence of an uplift during the early Turonian centered in northwestern Wyoming, west of the basin, probably associated with a eustatic event. The truncated Cenomanian strata were buried by lower middle Turonian beds during a marine transgression and possibly during regional subsidence and a eustatic rise. An uplift in the late middle Turonian, centered in north-central Wyoming and possibly associated with a eustatic fall, caused the erosion of lower middle Turonian beds in southern and eastern areas of the basin as well as in an adjoining region of north-central Wyoming. Similarly, in east-central Wyoming and an adjacent area to the south, Cenomanian strata are disconformably overlain by upper middle and lower upper Turonian strata that probably reflect uplift and erosion in that region during the interim period of middle Turonian time. During later subsidence and a marine transgression, upper Turonian deposits buried Cenomanian beds in areas along the south and east margins of the Bighorn Basin and buried lower middle Turonian beds in much of northern Wyoming. Upper Turonian and lower Coniacian strata are apparently conformable in eastern and southern areas of the basin as well as near Riverton, Kaycee, and Casper in central Wyoming. Upper Turonian strata are absent on the west flank of the Bighorn Basin and in outcrops west of the basin, where middle Turonian beds are disconformably overlain by lower Coniacian beds . The conformable upper Turonian and lower Coniacian beds apparently transgressed an eroded middle Turonian surface in the region, but only Coniacian strata overlie middle Turonian beds on the west side of the basin and areas farther west. Coniacian strata onlap the truncated lower middle Turonian surface west of the basin, indicating a region that had higher elevation possibly resulting from tectonic uplift. In east-central Wyoming and an adjoining region to the south, upper middle Turonian and lower upper Turonian strata are disconformably overlain by lower and middle Coniacian beds. That region apparently was uplifted and eroded during the latest Turonian.

Rational Use of Land Resource During the Implementation of Transportless System of Coal Strata Surface Mining

NASA Astrophysics Data System (ADS)

Gvozdkova, T.; Tyulenev, M.; Zhironkin, S.; Trifonov, V. A.; Osipov, Yu M.

2017-01-01

Surface mining and open pits engineering affect the environment in a very negative way. Among other pollutions that open pits make during mineral deposits exploiting, particular problem is the landscape changing. Along with converting the land into pits, surface mining is connected with pilling dumps that occupy large ground. The article describes an analysis of transportless methods of several coal seams strata surface mining, applied for open pits of South Kuzbass coal enterprises (Western Siberia, Russia). To improve land-use management of open pit mining enterprises, the characteristics of transportless technological schemes for several coal seams strata surface mining are highlighted and observed. These characteristics help to systematize transportless open mining technologies using common criteria that characterize structure of the bottom part of a strata and internal dumping schemes. The schemes of transportless systems of coal strata surface mining implemented in South Kuzbass are given.

Determination of the optimal level for combining area and yield estimates

NASA Technical Reports Server (NTRS)

Bauer, M. E. (Principal Investigator); Hixson, M. M.; Jobusch, C. D.

1981-01-01

Several levels of obtaining both area and yield estimates of corn and soybeans in Iowa were considered: county, refined strata, refined/split strata, crop reporting district, and state. Using the CCEA model form and smoothed weather data, regression coefficients at each level were derived to compute yield and its variance. Variances were also computed with stratum level. The variance of the yield estimates was largest at the state and smallest at the county level for both crops. The refined strata had somewhat larger variances than those associated with the refined/split strata and CRD. For production estimates, the difference in standard deviations among levels was not large for corn, but for soybeans the standard deviation at the state level was more than 50% greater than for the other levels. The refined strata had the smallest standard deviations. The county level was not considered in evaluation of production estimates due to lack of county area variances.

Earth's glacial record and its tectonic setting

NASA Astrophysics Data System (ADS)

Eyles, N.

1993-09-01

Glaciations have occurred episodically at different time intervals and for different durations in Earth's history. Ice covers have formed in a wide range of plate tectonic and structural settings but the bulk of Earth's glacial record can be shown to have been deposited and preserved in basins within extensional settings. In such basins, source area uplift and basin subsidence fulfill the tectonic preconditions for the initiation of glaciation and the accomodation and preservation of glaciclastic sediments. Tectonic setting, in particular subsidence rates, also dictates the type of glaciclastic facies and facies successions that are deposited. Many pre-Pleistocene glaciated basins commonly contain well-defined tectonostratigraphic successions recording the interplay of tectonics and sedimentation; traditional climatostratigraphic approaches involving interpretation in terms of either ice advance/retreat cycles or glacio-eustatic sea-level change require revision. The direct record of continental glaciation in Earth history, in the form of classically-recognised continental glacial landforms and "tillites", is meagre; it is probable that more than 95% of the volume of preserved "glacial" strata are glacially-influenced marine deposits that record delivery of large amounts of glaciclastic sediment to offshore basins. This flux has been partially or completely reworked by "normal" sedimentary processes such that the record of glaciation and climate change is recorded in marine successions and is difficult to decipher. The dominant "glacial" facies in the rock record are subaqueous debris flow diamictites and turbidites recording the selective preservation of poorly-sorted glaciclastic sediment deposited in deep water basins by sediment gravity flows. However, these facies are also typical of many non-glacial settings, especially volcanically-influenced environments; numerous Archean and Proterozoic diamictites, described in the older literature as tillites, have no clearly established glacial parentage. The same remarks apply to many successions of laminated and thin-bedded facies interpreted as "varvites". Despite suggestions of much lower values of solar luminosity (the weak young sun hypothesis), the stratigraphic record of Archean glaciations is not extensive and may be the result of non-preservation. However, the effects of very different Archean global tectonic regimes and much higher geothermal heat flows, combined with a Venus-like atmosphere warmed by elevated levels of CO 2, cannot be ruled out. The oldest unambiguous glacial succession in Earth history appears to be the Early Proterozoic Gowganda Formation of the Huronian Supergroup in Ontario; the age of this event is not well-constrained but glaciation coincided with regional rifting, and may be causally related to, oxygenation of Earth's atmosphere just after 2300 Ma. New evidence that oxygenation is tectonically, not biologically driven, stresses the intimate relationship between plate tectonics, evolution of the atmosphere and glaciation. Global geochemical controls, such as elevated atmospheric CO 2 levels, may be responsible for a long mid-Proterozoic non-glacial interval after 2000 Ma that was terminated by the Late Proterozoic glaciations just after 800 Ma. A persistent theme in both Late Proterozoic and Phanerozoic glaciations is the adiabatic effect of tectonic uplift, either along collisional margins or as a result of passive margin uplifts in areas of extended crust, as the trigger for glaciation; the process is reinforced by global geochemical feedback, principally the drawdown of atmospheric CO 2 and Milankovitch "astronomical" forcing but these are unlikely, by themselves, to inititiate glaciation. The same remarks apply to late Cenozoic glaciations. Late Proterozoic glacially-influenced strata occur on all seven continents and fall into two tectonostratigraphic types. In the first category are thick sucessions of turbidites and mass flows deposited along active, compressional plate margins recording a protracted and complex phase of supercontinent assembly between 800 and 550 Ma. Local cordilleran glaciations of volcanic peaks is indicated. Many deposits are preserved within mobile belts that record the subduction of interior oceans now preserved as "welds" between different cratons. Discrimination between glacially-influenced and non-glacial, volcaniclastic mass flow successions continues to be problematic. The second tectonostratigraphic category of Late Proterozoic glacial strata includes successions of glacially-influenced, mostly marine strata deposited along rifted, extensional plate margins. The oldest (Sturtian) glaciclastic sediments result from the break-out of Laurentia from the Late Proterozoic supercontinent starting around 750 Ma along its "palaeo-Pacific" margin with a later (Marinoan) phase of rifting at about 650 Ma. "Passive margin" uplifts and the generation of "adiabatic" ice covers on uplifted crustal blocks triggered widespread glaciation along the "palaeo-Pacific" margin of North America and in Australia. A major phase of rifting along the opposite ("palaeo-Atlantic") margin of Laurentia occurred after 650 Ma and is similarly recorded by glaciclastic strata in basins preserved around the margins of the present day North Atlantic Ocean. Glaciation of the west African platform after 650 Ma is closely related to collision of the West African and Guyanan cratons and uplift of the orogenic belt; the same process, involving uplift around the northern and western margins of the Afro-Arabian platform subsequently triggered Late Ordovician glaciation at about 440 Ma when the south polar region lay over North Africa. Early Silurian glaciation in Bolivia and Brazil was followed by a non-glacial episode and renewed Late Devonian glaciation of northern Brazil and Bolivia. The latter event may have resulted from rotation of Gondwana under the South Pole combined with active orogenesis along the western margin of the supercontinent. Hercynian uplift along the western margin of South America caused by the collision and docking of "Chilinia" at about 350 Ma (Late Tournasian—Early Visean) was the starting point of a long Late Palaeozoic glacial record that terminated at about 255 Ma (Kungurian-Kazanian) in western Australia. The arrival of large landmasses at high latitude may have been an important precondition for ice growth. Strong Namurian uplift around virtually the entire palaeo-Pacific rim of Gondwana culminated in glaciation of the interior of the supercontinent during the latest Westphalian (c. 300 Ma). There is a clear picture of plate margin compression and propagation of "far field" stresses to the plate interior allowing preservation of glacially-influenced strata in newly-rifted intracratonic basins. Many basins show a "steer's head" style of infill architecture recording successive phases of subsidence and overstepping of younger strata during basin subsidence and expansion. Exploration for oil and gas in Gondwanan glaciated basins is currently a major stimulus to understanding the relationship between tectonics and sedimentation. Warm Mesozoic palaeoclimates do not rule out the existence of restricted ice covers in the interiors of continental landmasses at high palaeolatitudes (e.g. Siberia, Antarctica) but there is as yet, no direct geological record of their existence. The most likely record of glaciers is contained in Late Jurassic and early Cretaceous strata. In any event, these ice masses are unlikely to have had any marked effect on global sea levels and alternative explanations should perhaps be sought for 4th order, so-called "glacio-eustatic" changes in sea level, inferred from Triassic, Jurassic and Cretaceous strata. The growth of extensive Northern Hemisphere ice sheets in Plio-Pleistocene time (c. 2.5 Ma) was the culmination of a long global climatic deterioration that began sometime after 60 Ma during the late Tertiary. Tectonic uplift of areas such as the Tibetan Plateau and plate tectonic reorganizations have been identified as first-order controls. Initiation of the East Antarctic ice sheet, at about 36 Ma, is the result of the progressive thermal isolation of the continent combined with uplift along the Transantarctic Mountains. In the Northern Hemisphere, the upwarping of extensive passive margin plateaux around the margins of the newly-rifted North Atlantic may have amplified global climatic changes and set the scene for the growth of continental ice sheets after 2.5 Ma. Ice sheet growth and decay was driven by complexly interrelated changes in ocean circulation, Milankovitch orbital forcing and global geochemical cycles. It is arguable whether continental glaciations of the Northern Hemisphere, and the evolution of hominids, would have occurred without the necessary precondition of tectonic uplift.

Seismic and chronostratigraphic results from SHALDRIL II, northwestern Weddell Sea

USGS Publications Warehouse

Anderson, J.B.; Wellner, J.; Wise, S.; Bohaty, S.; Manley, P.; Smith, T.; Weaver, F.; Kulhanek, D.

2007-01-01

The 2006 SHALDRIL II cruise was conducted in the northwestern Weddell Sea, with primary drilling targets in the James Ross Basin. A site drilled along the northern edge of the James Ross Basin sampled either latest Eocene or earliest Oligocene deposits, providing a lower chronostratigraphic benchmark for our seismic stratigraphic age model. Severe sea ice conditions forced abandonment of several of the James Ross Basin sites. Three alternate sites were drilled along the southern flank of the Joinville Plateau. Seismic data from the area show a thick, southward dipping stratigraphic succession with no conspicuous gaps. Three drill sites sampled this succession and recovered Oligocene, middle Miocene, and early Pliocene strata overlain by a thin drape of Pleistocene deposits. The Pliocene-Miocene boundary appears to be represented by a disconformity within the cored interval. Otherwise, this is one of the most complete post-Eocene successions anywhere on Antarctica and its adjacent margins

Water table dynamics in undisturbed, drained and restored blanket peat

NASA Astrophysics Data System (ADS)

Holden, J.; Wallage, Z. E.; Lane, S. N.; McDonald, A. T.

2011-05-01

SummaryPeatland water table depth is an important control on runoff production, plant growth and carbon cycling. Many peatlands have been drained but are now subject to activities that might lead to their restoration including the damming of artificial drains. This paper investigates water table dynamics on intact, drained and restored peatland slopes in a blanket peat in northern England using transects of automated water table recorders. Long-term (18 month), seasonal and short-term (storm event) records are explored. The restored site had drains blocked 6 years prior to monitoring commencing. The spatially-weighted mean water table depths over an 18 month period were -5.8 cm, -8.9 cm and -11.5 cm at the intact, restored and drained sites respectively. Most components of water table behaviour at the restored site, including depth exceedance probability curves, seasonality of water table variability, and water table responses to individual rainfall events were intermediate between that of the drained and intact sites. Responses also depended on location with respect to the drains. The results show that restoration of drained blanket peat is difficult and the water table dynamics may not function in the same way as those in undisturbed blanket peat even many years after management intervention. Further measurement of hydrological processes and water table responses to peatland restoration are required to inform land managers of the hydrological success of those projects.

Succession of insects on unreclaimed coal strip mine spoil banks in Indiana

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

Schrock, J.R.

1984-01-01

Selected sites at a western Indiana unreclaimed coal strip mine and adjacent undisturbed area sampled by Munsee in 1964 were restudied in 1981. Slope and exposure, soil pH and texture, vegetation and tree tallies, on-site rainfall and local weather records were used to characterize 18 spoilbanks and two unmined sites. Surface-active arthropods were sampled by replicated pitfall taps the summer of 1981 at the same locations and dates trapped by Munsee in 1964. Plant cover was sampled by a modified point-contact method. Trees over one inch dbh were tallied and measured for basal area. Clustering by similarity based on chi-squaremore » differences was performed for plants, trees, ants, springtails and ground beetles, using the undisturbed forest and a highly acid un-revegetated mined site as the extremes. Soil pH and texture changed rapidly on one moist spoilbank. Soil moisture levels generally decreased between 1964 and 1981 and depth of water penetration generally increased. Ant, springtail and carabid populations changed on revegetating sites. Myrmica spatulata and Smithistruma clypeata were major new ants on the sites in 1981. Iridomyrmex pruinosus analis and Pheidole bicarinata characteristic of barren spoilbanks in 1964 survived on only one remaining barren site in 1981. The collembolan Entomobrya quadrilineata decreased while Hypogastrura denticulata increased on the revegetating sites. Known habitat preference of some of these insects matched their occurrence on the spoilbanks.« less

Supercritical strata in Lower Paleozoic fluvial rocks: a super critical link to upper flow regime processes and preservation in nature

NASA Astrophysics Data System (ADS)

Lowe, David; Arnott, Bill

2015-04-01

Recent experimental work has much improved our understanding of the lithological attributes of open-channel supercritical flow deposits, namely those formed by antidunes, chutes-and-pools and cyclic steps. However their limited documentation in the ancient sedimentary record brings into question details about their geological preservation. Antidune, chute-and-pool and cyclic step deposits are well developed in sandy ephemeral fluvial deposits of the Upper Cambrian - Lower Ordovician Potsdam Group in the Ottawa Embayment of eastern North America. These high energy fluvial strata form dm- to a few m-thick units intercalated within thick, areally expansive successions of sheet sandstones consisting mostly of wind ripple and adhesion stratification with common deflation lags. Collectively these strata record deposition in a semi-arid environment in which rare, episodic high-energy fluvial events accounted for most of the influx of sediment from upland sources. Following deposition, however, extensive aeolian processes reworked the sediment pile, and hence modified profoundly the preserved stratigraphic record. Antidune deposits occur as 0.2 - 1.6 m thick cosets made up of 2 - 15 cm thick lenticular sets of low angle (≤ 20o) cross-stratified, medium- to coarse-grained sandstone bounded by low-angle (5 - 15o) concave-upward scours and, in many cases, capped by low angle (10 - 15o) convex-upwards symmetrical formsets. Chute-and-pool deposits form single sets, 5 - 55 cm thick and 0.6 - 6 m wide, with scoured bases and low to high angle (5 - 25o) sigmoidal cross-strata consisting of medium- to coarse-grained sandstone. Cyclic step deposits consist of trough cross-stratified sets, 20 cm - 1.6 m thick, 2.5 - 12 m long and 7 - 35 m wide, typically forming trains that laterally are erosively juxtaposed at regularly-spaced intervals. They are composed of medium- to coarse-grained sandstone with concave-up, moderate to high angle (15 - 35o) cross-strata with tangential bases that conform to the shape of the basal bounding surface of the set. Antidune and cyclic step deposits are common and fill 0.4 - 1.8 m deep channels, which then are generally overlain by extensive (>1 km) aeolian deflation surfaces. Chute-and-pool strata, however, are rare and only occur as isolated scour-filling sets within unconfined floodplain deposits. Nowhere in outcrop do different kinds of supercritical bedform deposits interfinger or appear related to the same flow event, suggesting that individual packages of supercritical strata were deposited by discreet, rapidly waning flows with little time for incremental growth or deposition under changing flow conditions. The stratal characteristics and geometries of channel-filling antidune and cyclic step cosets in the Potsdam are similar to those produced in steady experimental flows with high rates of aggradation. Similar conditions in the Potsdam were probably attained because the flows were channelized, which also caused the freshly deposited sediment to lie beneath the water table, and hence beneath the effects of extensive post-flood aeolian deflation. Conversely, scour-filling chute-and-pool deposits formed on the floodplain where highly unsteady, erosive and rapidly waning unconfined flows formed isolated, partly-filled, erosively-based, ephemeral structures. Moreover, being formed on the surface of the floodplain subjected these deposits to extensive post-depositional reworking, and as a consequence caused them to be poorly preserved.

Relation of the lower Pennsylvanian unconformity to a mid-carboniferous eustatic event in the eastern United States

USGS Publications Warehouse

Englund, K.J.; Thomas, R.E.

1997-01-01

Two contrasting concepts specifying the age and duration of the hiatus resulting from a mid-Carboniferous eustatic event in the eastern United States are based on different evidence. The original model indicated that the hiatus is at an unconformity in cratonic areas that was assumed to coincide with the Mississippian-Pennsylvanian boundary at the contact between the Mississippian Bluestone Formation and the Pennsylvanian Pocahontas Formation in the Appalachian foreland basin. This concept was adhered to exclusively until 1969 and continues to reappear in reports dealing with global correlations and division of the Carboniferous into the Mississippian and Pennsylvanian Systems. This division is at a major eustatic event that supposedly occurred at about 330 Ma in scattered parts of the world, including the Appalachian basin. An alternative concept, fully supported by geologic mapping and biostratigraphic studies, indicates that the unconformity and associated hiatus are much younger because they originate in the Appalachian foreland basin in the lower part (upper Namurian) of the Lower Pennsylvanian New River Formation, about 260 m above the Mississippian-Pennsylvanian boundary. The duration of this hiatus increases in a northwesterly direction onto the cratonic shelf because the unconformity progressively truncated the underlying Lower Pennsylvanian and Upper Mississippian successions. The westward onlap of Pennsylvanian strata onto the eroded surface resulted in a hiatus from the Early Mississippian (Tournaisian) to the Middle Pennsylvanian (Westphalian B). The systemic boundary, which is in a depositional continuous sequence of strata in the Appalachian foreland basin, was correlated biostratigraphically by Pfefferkorn and Gillespie in 1982 with Gothan's "Florensprung" (floral break) described in 1913 at the Namurian A-B boundary in the Upper Silesian basin. An intra-Namurian erosive event was noted also in the Upper Silesian basin by Havlena, who reported in 1982 that an intra-Namurian erosive contact occurs well above the Florensprung. The origin of the Florensprung in depositional continuous strata has been attributed to tectonism, environment, or climate. However, spherules found in depositional continuous strata near the Mississippian-Pennsylvanian boundary in the Appalachian basin indicate that the effect of an asteroid impact may be the underlying cause for the biodiversity noted at the systemic boundary.

Undergraduates Discovering Folds in ''Flat'' Strata: An Unusual Undergraduate Geology Field Methods Course

ERIC Educational Resources Information Center

Abolins, Mark

2014-01-01

Undergraduates learned to measure, map, and interpret bedding plane attitudes during a semesterlong geology field methods course in a field area where strata dip less than 98. Despite the low dip of the strata, 2011 field course students discovered a half-kilometer-wide structural basin by using digital levels and Brunton pocket transits to…

Initiation and evolution of the Arabia-Eurasia collision in the Caucasus region constrained by detrital zircon geochronology

NASA Astrophysics Data System (ADS)

Tye, A. R.; Niemi, N. A.

2016-12-01

The Greater Caucasus (GC) mountain range is composed of thrust sheets of Paleozoic (Pz) - Mesozoic (Mz) flysch. Crystalline basement is exposed in the western part of the range, but not in the eastern. Detrital zircon ages from Eocene - recent foreland strata to the south of the western GC in Georgia suggest sediment sourcing from GC basement or Pz strata since Eocene time, requiring significant exhumation prior to or coincident with the onset of Arabia-Eurasia collision 30 Ma. We sampled foreland basin sedimentary rocks and modern river sands whose catchment areas together span the potential source rocks exposed in the western Greater Caucasus (GC) in Georgia. We find that GC basement rocks and lower Pz strata contain a diagnostic 450 Ma zircon population that is absent from the upper Pz and Mz sedimentary strata that are exposed throughout most of the range. These 450 Ma zircons are from an unknown source with an age distinct from the Hercynian ( 300 Ma) and Pan-African ( 600 Ma) orogens. Despite their absence in late Pz and Mz strata, the 450 Ma zircons are prevalent in Eocene - recent foreland basin deposits, whose ages were determined biostratigraphically [1]. Paleocurrent directions also indicate a GC source for Eocene strata [2], necessitating early Cenozoic exposure of GC basement or Pz strata. Exposing GC basement or Pz strata during Eocene time requires erosional removal of >3500 m of Mesozoic and late Paleozoic strata [1]. The detrital zircon age observations suggest that erosional removal of these strata took place prior to the initiation of the Arabia-Eurasia collision at 30 Ma and well before the ongoing episode of rapid GC exhumation and erosion from 5 Ma - present. Foreland basin detrital zircon ages also reveal a lack of input from Late Cretaceous to Paleogene volcanism of the Adjara-Trialet zone. This finding is consistent with the existence of a Paleogene ocean basin between the Greater Caucasus and Lesser Caucasus wide enough to prevent transport of sand sized sediments from one side to the other. References[1] Gamkrelidze, P. D., & I. R. Kakhazdze (1959), K-38-VII, Min. Geol. Min. Prot. USSR. [2] Vincent, S. J., et al. (2007). Terra Nova, 19(2), 160-166. [3] Avdeev, B., & Niemi, N. A. (2011). Tectonics, 30(2), TC2009[4] Nalivkin, D. V. (1976). Geologic Map of the Caucasus, 1:500000.

Correlation, sedimentology, structural setting, chemical composition, and provenance of selected formations in Mesoproterozoic Lemhi Group, central Idaho

USGS Publications Warehouse

Tysdal, Russell G.; Lindsey, David A.; Taggart, Joseph E.

2003-01-01

A unit of the Mesoproterozoic Apple Creek Formation of the Lemhi Range previously was correlated with part of the lower subunit of the Mesoproterozoic Yellowjacket Formation in the Salmon River Mountains. Strata currently assigned to the middle subunit of the Yellowjacket Formation lie conformably above the Apple Creek unit in the Salmon River Mountains, and are here renamed the banded siltite unit and reassigned to the Apple Creek Formation. Almost all of the banded siltite unit is preserved within the Salmon River Mountains, where it grades upward into clastic rocks that currently are assigned to the upper subunit of the Yellowjacket Formation and that here are reassigned to the Gunsight Formation. The banded siltite unit of the Apple Creek Formation is composed of a turbidite sequence, as recognized by previous workers. Uppermost strata of the unit were reworked by currents, possibly storm generated, and adjusted to a high water content by developing abundant soft-sediment deformation features. Basal strata of the overlying Gunsight Formation in the Salmon River Mountains display abundant hummocky crossbeds, storm-generated features deposited below fair-weather wave base, that are conformable above the storm-reworked deposits. The hummocky crossbedded strata grade upward into marine shoreface strata deposited above fair-weather wave base, which in turn are succeeded by fluvial strata. Hummocky and shoreface strata are absent from the Gunsight Formation in the Lemhi Range. The major thickness of the Gunsight Formation in both the Salmon River Mountains and the Lemhi Range is composed of fluvial rocks, transitional in the upper part into marine rocks of the Swauger Formation. The fluvial strata are mainly characterized by stacked sheets of metasandstone and coarse siltite; they are interpreted as deposits of braided rivers. The Poison Creek thrust fault of the Lemhi Range extends northwestward through the study area in the east-central part of the Salmon River Mountains. The Apple Creek and Gunsight Formations on the southwest side of the thrust fault were transported to the northeast as part of the Poison Creek thrust sheet. A segment of the thrust fault within the Gunsight Formation in the Salmon River Mountains subsequently underwent normal displacement. Along this segment, lower Gunsight strata on the southwest were juxtaposed against upper Gunsight and Swauger strata on the northeast.

SlamZ: Slide activity on the Hikurangi margin, New Zealand - First results of the RV Sonne expedition SO247

NASA Astrophysics Data System (ADS)

Huhn, Katrin; Kukowski, Nina; Freudenthal, Tim; Crutchley, Gareth; Goepel, Andreas; Henrys, Stuart; Kasten, Sabine; Kaul, Norbert; Kuhlmann, Jannis; Mountjoy, Joshu; Orpin, Alan; Pape, Thomas; Schwarze, Cornelius; Totsche, Kai-Uwe; Torres, Marta; Villinger, Heiner

2017-04-01

Submarine landslides are important geologic hazards. Although they have been the focus of research for decades, there is still a clear lack in knowledge with respect to the interplay between tectonic movements, slope architecture and sediment physical properties of slope strata, as well as gas hydrate dissociation as controlling factors of slope stability or respectively slope failure processes. The main scientific goal of the Sonne expedition SO247 undertaken in spring 2016 was to gain a better understanding of the factors controlling slope destabilization, especially the interaction of tectonic steepening and gas hydrate transformation, at different tectonic settings along the Hikurangi subduction zone east of New Zealand's North Island. This active continental margin is characterized by various potential triggers for slope failure, e.g. (I) a wide range of tectonic movements which are associated with high seismicity, numerous active faults, sediment uplift and slope over-steepening, and (II) large gas hydrate deposits whose current upper stability limit in some places correlates with the breakoff points of slides. The target areas of SO247 were the frontal accretionary ridge at Rock Garden and the Tuaheni landslide complex (TLC) further north offshore Gisborne. Bathymetric as well as high-resolution seismic reflection and Parasound data were used to select suitable position for 53 gravity cores with a total length of 150 m which were recovered along systematic transects from the undisturbed slope sections to the slid masses in both working areas. In addition, six long sediment cores (three in both working areas) with a total length of approx. 470 m were drilled utilizing the MARUM Bremen drill rig MeBo200. These include a 105 m long continuous sediment core (core recovery > 95%) from an undisturbed slope section in the vicinity of the Tuaheni slide complex. This core represented the first long (i.e. longer than 50 m) sediment record from the Hikurangi margin. This drilling operation was paired with dense in-situ heat-flow measurements. Sedimentological, geotechnical, geophysical and geochemical analysis of the core material as well as sampled pore fluids and gases will enable a deeper insight into the slide kinematics, potential trigger mechanisms and timing of failure events. Furthermore, these data allow us to test hypotheses regarding the key role of sediment physical properties and/or gas hydrate dissociation and therewith the mechanics of submarine landslides; what are potential trigger mechanisms: uplift and over-steepening vs. sediment physical behaviour.

Assessment of Aeolis Palus stratigraphic relationships based on bench-forming strata in the Kylie and the Kimberley regions of Gale crater, Mars

NASA Astrophysics Data System (ADS)

Williams, Rebecca M. E.; Malin, Michael C.; Stack, Kathryn M.; Rubin, David M.

2018-07-01

The stratigraphic context of rock layers is a critical piece of information needed for accurate reconstruction of their geologic history. Although sedimentary rocks are widespread in Gale crater, efforts to deduce stratigraphic relationships of rocks were challenging early in the Mars Science Laboratory mission because vertical bedrock exposures were relatively rare along the first ∼3 km the rover traversed across Aeolis Palus. Potential insights into the three-dimensional configuration of rock layers were made once the rover passed Dingo Gap, especially in the informally-named Kylie and Kimberley regions. Here, the terrain exhibits low relief ( < 10 m) cliffs, some of which are continuous over lengths > 75 m. Curiosity Mastcam and Navcam images show that the cliffs are capped by resistant, bench-forming rock layers corresponding to two facies: a poorly sorted, weakly stratified pebble conglomerate, and a massive, dark-toned, vuggy sandstone. In places, the inclination of the topographic surface (northward ∼2° to 3°) is similar to the apparent dip of the underlying strata, suggesting the presence of dip slopes in an area inferred to be generally flat-lying, conformable rock units. Further, we assessed potential strata correlations via plane-fitting exercises and a regional comparison to other capping strata. We speculate that bench-forming strata in the study region could be part of a widespread package of draping strata (the Siccar Point group) that post-dates deposition and exhumation of the lower strata of Mount Sharp.

Necromass production: studies in undisturbed and logged Amazon Forests

Treesearch

MICHAEL PALACE; MICHAEL KELLER; HUDSON SILVA

2008-01-01

Necromass stocks account for up to 20% of carbon stored in tropical forests and have been estimated to be 14–19% of the annual aboveground carbon flux. Both stocks and fluxes of necromass are infrequently measured. In this study, we directly measured the production of fallen coarse necromass (>2 cm diameter) during 4.5 years using repeated surveys in undisturbed...

Necromass in undisturbed and logged forests in the Brazilian Amazon.

Treesearch

Michael Palace; Michael Keller; Gregory P. Asner; Jose Natalino M. Silva; Carlos Passos

2007-01-01

Necromass is an important stock of carbon in tropical forests. We estimated volume, density, and mass of fallen and standing necromass in undisturbed and selectively logged forests at Juruena, Mato Grosso, Brazil (10.488S, 58.478W). We also measured standing dead trees at the Tapajos National Forest, Para, Brazil (3.088S, 54.948W) complementing our earlier study there...

Coarse woody debris in undisturbed and logged forests in the eastern Brazilian Amazon.

Treesearch

Michael Keller; Michael Palace; Gregory P. Asner; Rodrigo Jr. Pereira; Jose Natalino M. Silva

2004-01-01

Coarse woody debris (CWD) is an important component of the carbon cycle in tropical forests. We measured the volume and density of fallen CWD at two sites, Cauaxi and Tapajós in the Eastern Amazon. At both sites we studied undisturbed forests (UFs) and logged forests 1 year after harvest. Conventional logging (CL) and reduced impact logging (RIL) were...

High duck nesting success in a predator-reduced environment

USGS Publications Warehouse

Duebbert, H.F.; Lokemoen, J.T.

1980-01-01

Duck nesting and production were studied during 1969-74 on a 51-ha field of undisturbed grass-legume cover and a surrounding 8.13-km2 area in north-central South Dakota. The principal mammalian predators of ducks were reduced within a 259-km2 zone from May 1969 through August 1971. Dabbling duck nest densities, hatching success, and breeding populations attained high levels. Seven duck species produced 1,062 nests on the 51-ha field during 6 years, 864 (81%) hatched, 146 (14%) were destroyed, and 52 (5%) had other fates. During 1970-72, when predator reduction was most effective, the hatching success for 756 nests was 94%. The number of mallard (Anas platyrhynchos) nests increased from 37 (0.7/ha) in 1969 to 181 (3.5/ha) in 1972. Mallard pairs increased from 2.8/km2 to 16.8/km2 on the 8.13-km2 area during the same period. A minimum of 7,250 ducklings hatched on the 51-ha field during the 6 years, including 2,342 ducklings in 1972. Exceptionally high duck nesting densities and hatching rates occurred when predators were controlled.

On the potential of long wavelength imaging radars for mapping vegetation types and woody biomass in tropical rain forests

NASA Technical Reports Server (NTRS)

Rignot, Eric J.; Zimmermann, Reiner; Oren, Ram

1995-01-01

In the tropical rain forests of Manu, in Peru, where forest biomass ranges from 4 kg/sq m in young forest succession up to 100 kg/sq m in old, undisturbed floodplain stands, the P-band polarimetric radar data gathered in June of 1993 by the AIRSAR (Airborne Synthetic Aperture Radar) instrument separate most major vegetation formations and also perform better than expected in estimating woody biomass. The worldwide need for large scale, updated biomass estimates, achieved with a uniformly applied method, as well as reliable maps of land cover, justifies a more in-depth exploration of long wavelength imaging radar applications for tropical forests inventories.

Self-revegetation of disturbed ground in the deserts of Nevada and Washington

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

Rickard, W.H.; Sauer, R.H.

1982-01-01

Plant cover established without purposeful soil preparation or seeding was measured on ground disturbed by plowing in Washington and by aboveground nuclear explosions in Nevada. After a time lapse of three decades in Washington and two decades in Nevada, fewer species were self-established on the disturbed ground than the nearby undisturbed ground. Alien annual plants were the dominants on the disturbed ground. Cheatgrass (Bromus tectorum) dominated abandoned fields in Washington, and filaree (Erodium cicutarium) dominated disturbed ground in Nevada. Perennial grasses and shrubs appeared to be more successful as invaders in Nevada than in Washington. This distinction is attributed tomore » the superior competitive ability of cheatgrass in Washington.« less

Ambiguities in model-independent partial-wave analysis

NASA Astrophysics Data System (ADS)

Krinner, F.; Greenwald, D.; Ryabchikov, D.; Grube, B.; Paul, S.

2018-06-01

Partial-wave analysis is an important tool for analyzing large data sets in hadronic decays of light and heavy mesons. It commonly relies on the isobar model, which assumes multihadron final states originate from successive two-body decays of well-known undisturbed intermediate states. Recently, analyses of heavy-meson decays and diffractively produced states have attempted to overcome the strong model dependences of the isobar model. These analyses have overlooked that model-independent, or freed-isobar, partial-wave analysis can introduce mathematical ambiguities in results. We show how these ambiguities arise and present general techniques for identifying their presence and for correcting for them. We demonstrate these techniques with specific examples in both heavy-meson decay and pion-proton scattering.

Mesozoic­ and Cenozoic Tectono-depositional History of the Southwestern Chukchi Borderland: Implications of Pre-Brookian Passive-margin Slope Deposits for the Jurassic Extensional Deformation of the Amerasia Basin, Arctic Ocean

NASA Astrophysics Data System (ADS)

Ilhan, I.; Coakley, B.

2016-12-01

A stratigraphic framework for offshore northwest of Alaska has been developed from multi-channel seismic reflection data and direct seismic-well ties to the late 80's Crackerjack and Popcorn exploration wells along the late Cretaceous middle Brookian unconformity. This unconformity is characterized by downlap, onlap, and bi-directional onlap of the overlying upper Brookian strata in high accommodation, and erosional incision of the underlying lower Brookian strata in low accommodation. This surface links multiple basins across the southwestern Chukchi Borderland, Arctic Ocean. The lower Brookian strata are characterized by pinch out basin geometry in which parallel-continuous reflectors show north-northeasterly progressive onlap of the younger strata onto a lower Cretaceous unconformity. These strata are subdivided into Aptian-Albian and Upper Cretaceous sections along a middle Cretaceous unconformity. The north-northeasterly thinning-by-onlap is consistent across hundreds of kilometers along the southwestern Chukchi Borderland. While this suggests a south-southwesterly regional source of sediment and transport from the Early Cretaceous Arctic Alaska-Chukotka orogens, pre-Brookian clinoform strata, underlying the lower Cretaceous unconformity angularly, have been observed for the first time in southeastern margin of the Chukchi Abyssal Plain. This suggests a change in sediment source and transport direction between the pre-Brookian and the lower Brookian strata. Although the mechanism for the accommodation is not well understood, we interpret the pre-Brookian strata as passive-margin slope deposits due to the fact that we have not observed any evidence for upper crustal tectonic deformation or syn-tectonic "growth" strata in the area. Thus, this implies that depositional history of the southwestern Chukchi Borderland post-dates the accommodation. This interpretation puts a new substantial constrain on the pre-Valanginian clockwise rotation of the Chukchi Borderland away from the East Siberian continental shelf, associated with the antecedent counter-clockwise rotation of the Arctic Alaska-Chukotka microplate away from the Canadian Arctic Islands and extensional deformation of the Amerasia Basin.

Shifting stream planform state decreases stream productivity yet increases riparian animal production.

PubMed

Venarsky, Michael P; Walters, David M; Hall, Robert O; Livers, Bridget; Wohl, Ellen

2018-05-01

In the Colorado Front Range (USA), disturbance history dictates stream planform. Undisturbed, old-growth streams have multiple channels and large amounts of wood and depositional habitat. Disturbed streams (wildfires and logging < 200 years ago) are single-channeled with mostly erosional habitat. We tested how these opposing stream states influenced organic matter, benthic macroinvertebrate secondary production, emerging aquatic insect flux, and riparian spider biomass. Organic matter and macroinvertebrate production did not differ among sites per unit area (m -2 ), but values were 2 ×-21 × higher in undisturbed reaches per unit of stream valley (m -1 valley) because total stream area was higher in undisturbed reaches. Insect emergence was similar among streams at the per unit area and per unit of stream valley. However, rescaling insect emergence to per meter of stream bank showed that the emerging insect biomass reaching the stream bank was lower in undisturbed sites because multi-channel reaches had 3 × more stream bank than single-channel reaches. Riparian spider biomass followed the same pattern as emerging aquatic insects, and we attribute this to bottom-up limitation caused by the multi-channeled undisturbed sites diluting prey quantity (emerging insects) reaching the stream bank (riparian spider habitat). These results show that historic landscape disturbances continue to influence stream and riparian communities in the Colorado Front Range. However, these legacy effects are only weakly influencing habitat-specific function and instead are primarily influencing stream-riparian community productivity by dictating both stream planform (total stream area, total stream bank length) and the proportional distribution of specific habitat types (pools vs riffles).

Fecal corticosterone, body mass, and caching rates of Carolina chickadees (Poecile carolinensis) from disturbed and undisturbed sites

PubMed Central

Lucas, Jeffrey R.; Freeberg, Todd M.; Egbert, Jeremy; Schwabl, Hubert

2006-01-01

We tested for hormonal and behavioral differences between Carolina chickadees (Poecile carolinensis) taken from a disturbed (recently logged) forest, an undisturbed forest, or a residential site. We measured fecal corticosterone and body mass levels in the field, and fecal corticosterone, body mass, and caching behavior in an aviary experiment. In the field, birds from the disturbed forest exhibited significantly higher fecal corticosterone levels than birds from either the undisturbed forest or from the residential site. Birds from the disturbed forest also exhibited lower body mass than those from the undisturbed forest but higher body mass than those from the residential site. Our aviary results suggest that these physiological differences between field sites are the result of short-term responses to ecological factors: Neither body mass nor fecal corticosterone levels varied between birds captured at different sites. Aviary sample sizes were sufficient to detect seasonal variation in fecal corticosterone (lowest in summer), body mass (highest in spring), and rate of gain in body mass (highest in winter). Under “closed-economy” aviary conditions (all food available from a feeder in the aviary), there were no site differences in the percent of seeds taken from the feeder that were cached. However, under “open-economy” conditions (food occasionally available ad libitum), significantly fewer seeds were cached by birds from the disturbed forest compared to the undisturbed or residential sites. On average, there was only a two-fold difference in population-levels of fecal corticosterone. This difference is about the same as an increase in fecal corticosterone induced by a two-hour increase in food deprivation, and can not be considered to be an acute stress response to disturbance. PMID:16458312

Emergence and growth of plant species in coal mine soil

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

Day, A.D.; Mitchell, G.F.; Tucker, T.C.

1979-01-01

Experiments were conducted in the laboratory and greenhouse in Arizona with the following objectives: to evaluate the chemical properties of undisturbed soil, surface-mined coal land (coal mine soil) on the Black Mesa Coal Mine, and Gila loam soil; and to study the emergence of seven plant species in the greenhouse in Gila loam soil and coal mine soil. The pH of coal mine soil (6.2) was lower than the pH of undisturbed soil (7.5) or Gila loam (7.6). The total soluble salts in coal mine soil (3241) and undisturbed soil (4592) were much higher than in Gila loam (378); however,more » coal mine soil was lower in total soluble salts than undisturbed soil. The nitrogen content of coal mine soil was higher than the nitrogen content of undisturbed soil or gila loam. Emergence percentages for seven plant species grown in coal mine soil were similar to emergence percentages for the same species grown in Gila loam. Alfalfa (Medicago sativa L.), barley (Hordeum vulgare L.), and wheat (Triticum aestivum L. em Thell.) had from 84 to 93% emergence in coal mine soil. Indian ricegrass (Oryzopsis hymenoides Roem. and Shult), fourwing saltbush (Atriplex canescens Pursh), yellow sweetclover (Melilotus officinalis Lam.), and winterfat (Euroti lanata Pursh.) emerged <35% in coal mine soil and Gila loam. Plant growth data from forage species grown in the greenhouse indicate that coal mine soil has a lower fertility level than does Gila loam soil. When supplied with optimum soil moisture and plant nutrients, coal mine soil produced approximately the same yields of forage from alfalfa, barley, and wheat as were produced in Gila loam under the same soil-moisture and fertility conditions.« less

Shifting stream planform state decreases stream productivity yet increases riparian animal production

USGS Publications Warehouse

Venarsky, Michael P.; Walters, David M.; Hall, Robert O.; Livers, Bridget; Wohl, Ellen

2018-01-01

In the Colorado Front Range (USA), disturbance history dictates stream planform. Undisturbed, old-growth streams have multiple channels and large amounts of wood and depositional habitat. Disturbed streams (wildfires and logging < 200 years ago) are single-channeled with mostly erosional habitat. We tested how these opposing stream states influenced organic matter, benthic macroinvertebrate secondary production, emerging aquatic insect flux, and riparian spider biomass. Organic matter and macroinvertebrate production did not differ among sites per unit area (m−2), but values were 2 ×–21 × higher in undisturbed reaches per unit of stream valley (m−1 valley) because total stream area was higher in undisturbed reaches. Insect emergence was similar among streams at the per unit area and per unit of stream valley. However, rescaling insect emergence to per meter of stream bank showed that the emerging insect biomass reaching the stream bank was lower in undisturbed sites because multi-channel reaches had 3 × more stream bank than single-channel reaches. Riparian spider biomass followed the same pattern as emerging aquatic insects, and we attribute this to bottom-up limitation caused by the multi-channeled undisturbed sites diluting prey quantity (emerging insects) reaching the stream bank (riparian spider habitat). These results show that historic landscape disturbances continue to influence stream and riparian communities in the Colorado Front Range. However, these legacy effects are only weakly influencing habitat-specific function and instead are primarily influencing stream–riparian community productivity by dictating both stream planform (total stream area, total stream bank length) and the proportional distribution of specific habitat types (pools vs riffles).

Effects of Disturbances on Vegetation Composition and Permafrost Thaw in Boreal Forests and Tundra Ecosystems of the Siberian Arctic

NASA Astrophysics Data System (ADS)

Ramos, E.; Alexander, H. D.; Natali, S.

2014-12-01

In Arctic ecosystems, climate-driven changes to the thermal regime of permafrost soils have the potential to create surface disturbances that influence vegetation dynamics and underlying soil properties. Disturbance-mediated changes in vegetation are important because vegetation and the accumulation of soil organic matter drive ecosystem carbon (C) dynamics and contribute to the insulation of soils and protection of permafrost from thaw. We examined the effect of two disturbance types—thermokarsts and frost boils—to determine disturbance effects on the vegetation community and soil properties in northeast Siberia. In summer 2014, we measured vegetation cover, soil moisture, soil temperature, and thaw depth in two thermokarst sites within boreal forests, two frost boil sites in tundra, and in adjacent undisturbed sites within both ecosystems. Both thermokarst and frost boils resulted in decreased vegetation cover and greater exposure of mineral soils (10-40% bare soils vs. 0% in undisturbed), and consequently, 2-3 times higher soil temperature and deeper thaw depth. Compared to undisturbed areas, soil moisture was 3-4 times higher in thermokarst areas but 1.2-2 times lower in frost boil areas, which reflected differences in microtopography between these two disturbance types. In both thermokarst and frost boil disturbed areas, deciduous and evergreen shrubs covered only 5 and 10%, respectively, compared to approximately 10 and 20%, respectively, in undisturbed areas. In general, graminoids were substantially more abundant (2-20 times) in disturbed areas than in those undisturbed. These results highlight important linkages between disturbances, vegetation communities, and permafrost soils, and contribute to our understanding of how changes in arctic vegetation dynamics as direct and/or indirect consequences of climate change have the potential to impact permafrost C pools.

A simple hypothesis of how leaf and canopy-level transpiration and assimilation respond to elevated CO2 reveals distinct response patterns between disturbed and undisturbed vegetation

NASA Astrophysics Data System (ADS)

Donohue, Randall J.; Roderick, Michael L.; McVicar, Tim R.; Yang, Yuting

2017-01-01

Elevated CO2 increases leaf-level water-use efficiency (ω) almost universally. How canopy-level transpiration and assimilation fluxes respond to increased ω is currently unclear. We present a simple, resource-availability-based hypothesis of how equilibrium (or mature) leaf and canopy transpiration and assimilation rates, along with leaf area index (L), respond to elevated CO2. We quantify this hypothesis in the form of a model and test it against observations from eight Free Air CO2 Enrichment sites that span a wide range of resource availabilities. Sites were grouped according to vegetation disturbance status. We find the model adequately accounts for the responses of undisturbed vegetation (R2 = 0.73, 11% error) but cannot account for the responses of disturbed vegetation (R2 = 0.47, 17% error). At undisturbed sites, the responses of L and of leaf and canopy transpiration vary predictably (7% error) with resource availability, whereas the leaf assimilation response is less predictable. In contrast, the L and transpiration flux responses at the disturbed (mostly forested) sites are highly variable and are not strongly related to resource availability. Initial analyses suggest that they are more strongly related to regrowth age than to resource availability. We conclude that (i) our CO2 response hypothesis is valid for capturing the responses of undisturbed vegetation only, (ii) that the responses of disturbed vegetation are distinctly different from undisturbed vegetation, and (iii) that these differences need to be accounted for when predicting the effects of elevated CO2 on land surface processes generally, and on leaf area and water fluxes in particular.

Exploring the use of environmental DNA to determine the species of salmon redds

USGS Publications Warehouse

Strobel, Burke; Laramie, Matthew; Pilliod, David S.

2017-01-01

Annual redd counts are used to monitor the status and trends of salmonid populations, but methods to easily and reliably determine which of sympatric species made specific redds are lacking. We explored whether environmental DNA (eDNA) analysis might prove useful for determining the species of salmon redds. We collected eDNA samples from the interstitial spaces of redds of Chinook Salmon Oncorhynchus tshawytscha, redds of Coho Salmon O. kisutch, and areas of undisturbed gravel (n = 10, each), as well as from the water column adjacent to each of those sites in the Sandy River basin, Oregon, USA during the fall of 2013. The concentrations of Chinook and Coho eDNA were quantified within each sample using real-time PCR. The water in the interstitial spaces of redds contained significantly higher eDNA concentrations of the species that made the redd than (1) the other species and (2) the adjacent water column. In contrast, neither Chinook nor Coho eDNA was significantly more concentrated than the other in the water from the interstitial spaces of undisturbed gravel. The interstitial water of undisturbed gravel contained significantly higher eDNA concentrations of Coho than the adjacent water column. In contrast, Chinook eDNA concentration was similar in the interstitial water of undisturbed gravel and the adjacent water column. Both species’ redds had significantly higher concentrations of their respective species’ eDNA than did undisturbed gravel, but conclusions were confounded by differences in the timing and locations of sampling. This initial investigation highlights the potential value and some of the complexity of using eDNA analysis to indicate redd species.

Unusual seismogenic soft-sediment deformation structures in Cambrian epicratonic carbonate deposits, western Colorado, U.S.A

NASA Astrophysics Data System (ADS)

Myrow, P.; Chen, J.

2013-12-01

A wide variety of unusual penecontemporaneous deformation structures exist in grainstone and flat-pebble conglomerate beds of the Upper Cambrian strata, western Colorado, including slide scarps, thrusted beds, irregular blocks and internally deformed beds. Slide scarps are characterized by concave-up, sharp surfaces that truncate one or more underlying beds. Thrusted beds record movement of a part of a bed onto itself along a moderate to steeply inclined (generally 25°-40°) ramp. The hanging wall lenses in cases show fault-bend geometries, with either intact or mildly deformed bedding. Irregular bedded to internally deformed blocks isolated on generally flat upper bedding surfaces are similar in composition to the underlying beds. These features represent parts of beds that were detached, moved up onto, and some distances across, the laterally adjacent undisturbed bed surfaces. The blocks moved either at the sediment-water interface or intrastratally at shallow depths within overlying muddy deposits. Finally, internally deformed beds have large blocks, fitted fabrics of highly irregular fragments, and contorted lamination, which represent heterogeneous deformation, such as brecciation and liquefaction. The various deformation structures were most probably triggered by earthquakes, considering the nature of deformation (regional distribution of liquefaction structures, and the brittle segmentation and subsequent transportation of semi-consolidated beds) and the reactivation of Mesoproterozoic, crustal-scale shear zones in the central Rockies during the Late Cambrian. Features produced by initial brittle deformation are unusual relative to most reported seismites, and may represent poorly recognized to unrecognized seismogenic structures in the rock record.

Sequence stratigraphy, paleoclimate, and tectonics of coal-bearing strata

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

Jack C. Pashin; Robert A. Gastaldo

2004-07-15

The origin of coal-bearing strata has been debated vigorously for more than a century, and with the emergence of coalbed methane as a major energy resource and the possibility of sequestering greenhouse gas in coal, this debate has never been more relevant. This volume contains 10 chapters on coal-bearing strata of Carboniferous through Tertiary age and is based on a special session that was held at an AAPG Annual Meeting in New Orleans. Contributors have employed a multitude of approaches ranging from basin analysis to plant taphonomy to support a variety of views on the sequence stratigraphy, paleoclimate, and tectonicsmore » of coal-bearing strata.« less

K/T boundary stratigraphy: Evidence for multiple impacts and a possible comet stream

NASA Technical Reports Server (NTRS)

Shoemaker, E. M.; Izett, G. A.

1992-01-01

A critical set of observations bearing on the K/T boundary events were obtained from several dozen sites in western North America. Thin strata at and adjacent to the K/T boundary are locally preserved in association with coal beds at these sites. The strata were laid down in local shallow basins that were either intermittently flooded or occupied by very shallow ponds. Detailed examination of the stratigraphy at numerous sites led to the recognition of two distinct strata at the boundary. From the time that the two strata were first recognized, E.M. Shoemaker has maintained that they record two impact events. We report some of the evidence that supports this conclusion.

Socioeconomic inequalities and vaccination coverage: results of an immunisation coverage survey in 27 Brazilian capitals, 2007-2008.

PubMed

Barata, Rita Barradas; Ribeiro, Manoel Carlos Sampaio de Almeida; de Moraes, José Cássio; Flannery, Brendan

2012-10-01

Since 1988, Brazil's Unified Health System has sought to provide universal and equal access to immunisations. Inequalities in immunisation may be examined by contrasting vaccination coverage among children in the highest versus the lowest socioeconomic strata. The authors examined coverage with routine infant immunisations from a survey of Brazilian children according to socioeconomic stratum of residence census tract. The authors conducted a household cluster survey in census tracts systematically selected from five socioeconomic strata, according to average household income and head of household education, in 26 Brazilian capitals and the federal district. The authors calculated coverage with recommended vaccinations among children until 18 months of age, according to socioeconomic quintile of residence census tract, and examined factors associated with incomplete vaccination. Among 17,295 children with immunisation cards, 14,538 (82.6%) had received all recommended vaccinations by 18 months of age. Among children residing in census tracts in the highest socioeconomic stratum, 77.2% were completely immunised by 18 months of age versus 81.2%-86.2% of children residing in the four census tract quintiles with lower socioeconomic indicators (p<0.01). Census tracts in the highest socioeconomic quintile had significantly lower coverage for bacille Calmette-Guérin, oral polio and hepatitis B vaccines than those with lower socioeconomic indicators. In multivariable analysis, higher birth order and residing in the highest socioeconomic quintile were associated with incomplete vaccination. After adjusting for interaction between socioeconomic strata of residence census tract and household wealth index, only birth order remained significant. Evidence from Brazilian capitals shows success in achieving high immunisation coverage among poorer children. Strategies are needed to reach children in wealthier areas.

Socioeconomic inequalities and vaccination coverage: results of an immunisation coverage survey in 27 Brazilian capitals, 2007–2008

PubMed Central

Sampaio de Almeida Ribeiro, Manoel Carlos; de Moraes, José Cássio; Flannery, Brendan

2012-01-01

Background Since 1988, Brazil's Unified Health System has sought to provide universal and equal access to immunisations. Inequalities in immunisation may be examined by contrasting vaccination coverage among children in the highest versus the lowest socioeconomic strata. The authors examined coverage with routine infant immunisations from a survey of Brazilian children according to socioeconomic stratum of residence census tract. Methods The authors conducted a household cluster survey in census tracts systematically selected from five socioeconomic strata, according to average household income and head of household education, in 26 Brazilian capitals and the federal district. The authors calculated coverage with recommended vaccinations among children until 18 months of age, according to socioeconomic quintile of residence census tract, and examined factors associated with incomplete vaccination. Results Among 17 295 children with immunisation cards, 14 538 (82.6%) had received all recommended vaccinations by 18 months of age. Among children residing in census tracts in the highest socioeconomic stratum, 77.2% were completely immunised by 18 months of age versus 81.2%–86.2% of children residing in the four census tract quintiles with lower socioeconomic indicators (p<0.01). Census tracts in the highest socioeconomic quintile had significantly lower coverage for bacille Calmette-Guérin, oral polio and hepatitis B vaccines than those with lower socioeconomic indicators. In multivariable analysis, higher birth order and residing in the highest socioeconomic quintile were associated with incomplete vaccination. After adjusting for interaction between socioeconomic strata of residence census tract and household wealth index, only birth order remained significant. Conclusions Evidence from Brazilian capitals shows success in achieving high immunisation coverage among poorer children. Strategies are needed to reach children in wealthier areas. PMID:22268129

Model for turbidite-to-contourite continuum and multiple process transport in deep marine settings: examples in the rock record

NASA Astrophysics Data System (ADS)

Stanley, Daniel Jean

1993-01-01

Petrological analysis of geological sections in St. Croix in the Caribbean, the Niesenflysch in Switzerland and the Annot Sandstone in the French Maritime Alps sheds light on multiple process transport in deep marine settings. A model depicting a turbidite-to-contourite continuum of stratal types is applied to these three rock units. Recognition of a diverse suite of bedforms, coupled with analysis of paleocurrents, helps to better interpret depositional origin and basin paleogeography. The St. Croix strata record emplacement by gravity flows and, subsequently, by bottom currents flowing parallel to the base of slope; these sediments accumulated on a lower slope apron. A Niesenflysch section in the Swiss Alps west of Adelboden includes turbidites which were deposited at fairly regular intervals beyond the base of slope, in a setting more distal than that of the St. Croix sequences. Most of these turbidites appear to have been partially reworked by bottom currents related to basin circulation or to density flows from the basin margins. In the Annot Sandstone, reworked turbidites (termed transitional variants) and packets of entirely rippled strata are observed in submarine fan and slope sequences in the Peira-Cava area. In contrast to those in St. Croix and the Niesenflysch, the current-emplaced deposits of the Annot Sandstone are directly associated with fan-valley deposits. Such rippled strata in channels are deposits of gravity flow origin which were subsequently reworked downslope by currents generated by successive gravity flows; they also occur on levees by overbank flow. Consideration of multiple process transport is of special help to interpret sections which are poorly exposed, or which can be examined in cores, or which are located in sequences that have been highly deformed structurally.

A quasi-Hertzian stress field from an internal source: A possible working model for the Vredefort structure

NASA Technical Reports Server (NTRS)

Antoine, L. A. G.; Reimold, W. U.; Colliston, W. P.

1992-01-01

The Vredefort structure is a large domal feature about 110 km southeast of Johannesburg, South Africa, situated within and almost central to the large intracratonic Witwatersrand Basin. This structure consists of an Archean core of ca. 45 km in diameter, consisting largely of granitic gneiss, surrounded by a collar of metasedimentary and metavolcanic supracrustal rocks of the Dominian Group, Witwatersrand and Ventersdorp Supergroups, and Transvaal Sequence. The interpretation of images of the gravity and magnetic fields over Vredefort has permitted the delineation of several important features of the structure and of its environment. The outline of the collar strata is a prominent feature of both the gravity and the magnetic fields. The Vredefort structure shares this distinctive geometry with other structures (e.g., Manicouagan, Decaturville, Sierra Madera) of debated impact origin. In all these, successively older strata with steep outward dips are encountered while traversing inward to the center of the structure. A further attribute of these structures is the shortening of the outcrop of a particular stratigraphic unit compared to the original perimeter of that unit. To account for the geometric attributes of the Vredefort structure a mechanical scheme is required where there is radial movement of horizontal strata toward, with uplift in, the center of the Vredefort structure. Two models can be proposed: (1) one in which there is a rapid rise and violent disruption of cover rocks in response to expansion of a fluid accumulation; and (2) one in which there is, in contrast, a nonexplosive, quasi-Hertzian stress field resulting from a diapiric process. Both models can accommodate the geometry and structural components of Vredefort.

Longitudinal variation in suspended sediment and turbidity of two undisturbed streams in northwestern California in relation to the monitoring of water quality above and below a land disturbance

Treesearch

Steve G. Markman

1990-01-01

Abstract - In-stream water quality regulations of California state that silvicultural disturbances must not increase turbidity levels more than 20 percent above naturally occurring background levels. These regulations fail to take into account the natural variation of turbidity and suspended sediment concentration along a short stretch of an undisturbed stream. At...

Distribution of tree species in an undisturbed northern hardwood-spruce-fir forest, the Bowl, N. H.

Treesearch

C. Wayne Martin

1977-01-01

Knowledge acquired from forests that have never been logged can provide clues to the long-term effects of resource utilization. In 1974, a survey was made of the vegetation of the Bowl Research Natural Area in central New Hampshire, known to be undisturbed by humans; and an adjacent watershed known to have been logged in the late 1880's. There were no significant...

Management of an undisturbed water ecosystem containing old growth hemlock, as a model system of Clear Lake Reserve, Ontario

Treesearch

A. M. Zobel; R. A. Reid; K. Cybulski; K. Glowniak; O. Loucks; J. E. Nighswander

2000-01-01

Since 1969 Trent University researchers have been investigating the chemistry and biotic part of a small undisturbed lake near Minden, Ontario. Clear Lake is surrounded by old growth hemlock stands, some 400 years old. The research was later joined by personnel of the Ontario Ministry of the Environment, and the educational program in the Frost Centre. We are going to...

Extreme late-summer drought causes neutral annual carbon balance in southwestern ponderosa pine forests and grasslands

NASA Astrophysics Data System (ADS)

Kolb, Thomas; Dore, Sabina; Montes-Helu, Mario

2013-03-01

We assessed the impacts of extreme late-summer drought on carbon balance in a semi-arid forest region in Arizona. To understand drought impacts over extremes of forest cover, we measured net ecosystem production (NEP), gross primary production (GPP), and total ecosystem respiration (TER) with eddy covariance over five years (2006-10) at an undisturbed ponderosa pine (Pinus ponderosa) forest and at a former forest converted to grassland by intense burning. Drought shifted annual NEP from a weak source of carbon to the atmosphere to a neutral carbon balance at the burned site and from a carbon sink to neutral at the undisturbed site. Carbon fluxes were particularly sensitive to drought in August. Drought shifted August NEP at the undisturbed site from sink to source because the reduction of GPP (70%) exceeded the reduction of TER (35%). At the burned site drought shifted August NEP from weak source to neutral because the reduction of TER (40%) exceeded the reduction of GPP (20%). These results show that the lack of forest recovery after burning and the exposure of undisturbed forests to late-summer drought reduce carbon sink strength and illustrate the high vulnerability of forest carbon sink strength in the southwest US to predicted increases in intense burning and precipitation variability.

Mangrove removal in the belize cays: effects on mangrove-associated fish assemblages in the intertidal and subtidal

USGS Publications Warehouse

Taylor, D.S.; Reyier, E.A.; Davis, W.P.; McIvor, C.C.

2007-01-01

We investigated the effects of mangrove cutting on fish assemblages in Twin Cays, Belize, in two habitat types. We conducted visual censuses at two sites in adjoining undisturbed/disturbed (30%–70% of shoreline fringe removed) sub-tidal fringing Rhizophora mangle Linnaeus, 1753. Observers recorded significantly more species and individuals in undisturbed sites, especially among smaller, schooling species (e.g., atherinids, clupeids), where densities were up to 200 times greater in undisturbed habitat. Multivariate analyses showed distinct species assemblages between habitats at both sites. In addition, extensive trapping with wire minnow traps within the intertidal zone in both undisturbed and disturbed fringing and transition (landward) mangrove forests was conducted. Catch rates were low: 638 individuals from 24 species over 563 trap-nights. Trap data, however, indicated that mangrove disturbance had minimal effect on species composition in either forest type (fringe/transition). Different results from the two methods (and habitat types) may be explained by two factors: (1) a larger and more detectable species pool in the subtidal habitat, with visual "access" to all species, and (2) the selective nature of trapping. Our data indicate that even partial clearing of shoreline and more landward mangroves can have a significant impact on local fish assemblages.

[Effect of trampling disturbance on soil infiltration of biological soil crusts].

PubMed

Shi, Ya Fang; Zhao, Yun Ge; Li, Chen Hui; Wang, Shan Shan; Yang, Qiao Yun; Xie, Shen Qi

2017-10-01

The effect of trampling disturbance on soil infiltration of biological soil crusts was investigated by using simulated rainfall. The results showed that the trampling disturbance significantly increased soil surface roughness. The increasing extent depended on the disturbance intensity. Soil surface roughness values at 50% disturbance increased by 91% compared with the undisturbed treatment. The runoff was delayed by trampling disturbance. A linear increase in the time of runoff yield was observed along with the increasing disturbance intensity within 20%-50%. The time of runoff yield at 50% disturbance increased by 169.7% compared with the undisturbed treatment. Trampling disturbance increased soil infiltration and consequently decreased the runoff coefficient. The cumulative infiltration amount at 50% disturbance increased by 12.6% compared with the undisturbed treatment. Soil infiltration significant decreased when biocrusts were removed. The cumulative infiltration of the treatment of biocrusts removal decreased by 30.2% compared with the undisturbed treatment. Trampling disturbance did not significantly increase the soil loss when the distur bance intensity was lower than 50%, while the biocrusts removal resulted in 10 times higher in soil erosion modulus. The trampling disturbance of lower than 50% on biocrusts might improve soil infiltration and reduce the risk of runoff, thus might improve the soil moisture without obviously increa sing the soil loss.

[Assessment on vegetation restoration capacity of several grassland ecosystems under destroyed disturbance in permafrost regions of Qinghai-Tibet Plateau].

PubMed

Li, Dong-Ming; Guo, Zheng-Gang; An, Li-Zhe

2008-10-01

Vegetation restoration capacity of disturbed grassland ecosystem is one of the important components in assessing the influence of human engineering activities on the grassland ecosystems in permafrost region of Qinghai-Tibet Plateau. After comparing the features of vegetation communities, plant species diversity, grassland primary productivity, and economic group between disturbed and undisturbed communities, the comprehensive vegetation restoration capacity of several grassland communities under destroyed disturbance was assessed by using comprehensive assessment index. The results showed that the restoration of cover and community composition was obvious after 26 years natural restoration, being better for alpine steppes than for alpine meadows. However, the cover of disturbed communities was less than that of undisturbed communities. The restoration of plant species diversity in Stipa purpurea steppe was better than that in other grassland types. The biomass of standing plants restored from 0 to 148.8-489.6 g x m(-2), and that of Kobresia tibetica meadow was the highest (489.6 g x m(-2)). The palatable plants of disturbed communities were lower than those of undisturbed communities except for K. tibetica meadow, in which, the palatable plants were not changeable between disturbed and undisturbed communities. The comprehensive vegetation restoration capacity of alpine steppes was better than that of alpine meadows.

Disentangling the drivers of taxonomic and phylogenetic beta diversities in disturbed and undisturbed subtropical forests

NASA Astrophysics Data System (ADS)

Liu, Jinliang; Qian, Hong; Jin, Yi; Wu, Chuping; Chen, Jianhua; Yu, Shuquan; Wei, Xinliang; Jin, Xiaofeng; Liu, Jiajia; Yu, Mingjian

2016-10-01

Understanding the relative importance of dispersal limitation and environmental filtering processes in structuring the beta diversities of subtropical forests in human disturbed landscapes is still limited. Here we used taxonomic (TBD) and phylogenetic (PBD), including terminal PBD (PBDt) and basal PBD (PBDb), beta diversity indices to quantify the taxonomic and phylogenetic turnovers at different depths of evolutionary history in disturbed and undisturbed subtropical forests. Multiple linear regression model and distance-based redundancy analysis were used to disentangle the relative importance of environmental and spatial variables. Environmental variables were significantly correlated with TBD and PBDt metrics. Temperature and precipitation were major environmental drivers of beta diversity patterns, which explained 7-27% of the variance in TBD and PBDt, whereas the spatial variables independently explained less than 1% of the variation for all forests. The relative importance of environmental and spatial variables differed between disturbed and undisturbed forests (e.g., when Bray-Curtis was used as a beta diversity metric, environmental variable had a significant effect on beta diversity for disturbed forests but had no effect on undisturbed forests). We conclude that environmental filtering plays a more important role than geographical limitation and disturbance history in driving taxonomic and terminal phylogenetic beta diversity.

Disentangling the drivers of taxonomic and phylogenetic beta diversities in disturbed and undisturbed subtropical forests

PubMed Central

Liu, Jinliang; Qian, Hong; Jin, Yi; Wu, Chuping; Chen, Jianhua; Yu, Shuquan; Wei, Xinliang; Jin, Xiaofeng; Liu, Jiajia; Yu, Mingjian

2016-01-01

Understanding the relative importance of dispersal limitation and environmental filtering processes in structuring the beta diversities of subtropical forests in human disturbed landscapes is still limited. Here we used taxonomic (TBD) and phylogenetic (PBD), including terminal PBD (PBDt) and basal PBD (PBDb), beta diversity indices to quantify the taxonomic and phylogenetic turnovers at different depths of evolutionary history in disturbed and undisturbed subtropical forests. Multiple linear regression model and distance-based redundancy analysis were used to disentangle the relative importance of environmental and spatial variables. Environmental variables were significantly correlated with TBD and PBDt metrics. Temperature and precipitation were major environmental drivers of beta diversity patterns, which explained 7–27% of the variance in TBD and PBDt, whereas the spatial variables independently explained less than 1% of the variation for all forests. The relative importance of environmental and spatial variables differed between disturbed and undisturbed forests (e.g., when Bray-Curtis was used as a beta diversity metric, environmental variable had a significant effect on beta diversity for disturbed forests but had no effect on undisturbed forests). We conclude that environmental filtering plays a more important role than geographical limitation and disturbance history in driving taxonomic and terminal phylogenetic beta diversity. PMID:27775021

In situ reactor

DOEpatents

Radtke, Corey William; Blackwelder, David Bradley

2004-01-27

An in situ reactor for use in a geological strata, is described and which includes a liner defining a centrally disposed passageway and which is placed in a borehole formed in the geological strata; and a sampling conduit is received within the passageway defined by the liner and which receives a geological specimen which is derived from the geological strata, and wherein the sampling conduit is in fluid communication with the passageway defined by the liner.

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

Saller, A.H.; Schlanger, S.O.

Two wells drilled along the margin of Enewetak Atoll penetrated approximately 1,000 m of upper eocene, Oligocene, and lower Miocene carbonates. STrontium isotope stratigraphy indicates relatively continuous deposition of carbonate from 40 Ma to 20 Ma. Depositional environments show a gradual basinward progradation of facies with slope carbonates passing upward into fore-reef, reef, back-reef, and lagoonal carbonates. Slope strata contain wackestones and packstones with submarine-cemented lithoclasts, coral, coralline algae fragments, benthic rotaline forams, planktonic forams, and echinoderm fragments. Fore-reef strata are dominantly packstones and boundstones containing large pieces of coral, abundant benthic forams, coralline algae fragments, stromatoporoids(.), and minor planktonicmore » forams. Reef and near-reef sediments include coralgal boundstones and grainstones with abundant benthic forams. Halimeda and miliolid forams are common in lagoonward parts of the back reef. Sponge borings, geopetal structures, and fractures are common in reef and fore-reef strata. Lagoonal strata are wackestones and packstones with common mollusks, coral, coralline algae, and benthic forams (rotaline and miliolid). Diagenesis has extensively altered strata near the atoll margin. Aragonite dissolution and calcite cements (radiaxial and cloudy prismatic are abundant in fore-reef, reef, and some back-reef strata). Petrographic and geochemical data indicate arogonite dissolution and calcite cementation in seawater at burial depths of 100 to 300 m. Dolomite occurs in slope and deeply buried reefal carbonates.« less

Permeability Prediction in Deep Coal Seam: A Case Study on the No. 3 Coal Seam of the Southern Qinshui Basin in China

PubMed Central

2013-01-01

The coal permeability is an important parameter in mine methane control and coal bed methane (CBM) exploitation, which determines the practicability of methane extraction. Permeability prediction in deep coal seam plays a significant role in evaluating the practicability of CBM exploitation. The coal permeability depends on the coal fractures controlled by strata stress, gas pressure, and strata temperature which change with depth. The effect of the strata stress, gas pressure, and strata temperature on the coal (the coal matrix and fracture) under triaxial stress and strain conditions was studied. Then we got the change of coal porosity with strata stress, gas pressure, and strata temperature and established a coal permeability model under tri-axial stress and strain conditions. The permeability of the No. 3 coal seam of the Southern Qinshui Basin in China was predicted, which is consistent with that tested in the field. The effect of the sorption swelling on porosity (permeability) firstly increases rapidly and then slowly with the increase of depth. However, the effect of thermal expansion and effective stress compression on porosity (permeability) increases linearly with the increase of depth. The most effective way to improve the permeability in exploiting CBM or extracting methane is to reduce the effective stress. PMID:24396293

Numerical study on the responses of groundwater and strata to pumping and recharge in a deep confined aquifer

NASA Astrophysics Data System (ADS)

Zhang, Yang-Qing; Wang, Jian-Hua; Chen, Jin-Jian; Li, Ming-Guang

2017-05-01

Groundwater drawdown and strata settlements induced by dewatering in confined aquifers can be relieved by artificial recharge. In this study, numerical simulations of a field multi-well pumping-recharge test in a deep confined aquifer are conducted to analyze the responses of groundwater and strata to pumping and recharge. A three-dimensional numerical model is developed in a finite-difference software, which considers the fluid-mechanical interaction using the Biot consolidation theory. The predicted groundwater drawdown and ground settlements are compared to the measured data to confirm the validation of the numerical analysis of the pumping and recharge. Both numerical results and measured data indicate that the effect of recharge on controlling the groundwater drawdown and strata settlements correlates with the injection rate and well arrangements. Since the groundwater drawdown induced by pumping can be controlled by artificial recharge, soil compression can be relieved by reducing the changes of effective stress of the soils. Consequently, strata settlement induced by pumping can be relieved by artificial recharge and ground settlements can be eliminated if an appropriate injection rate and well arrangement are being determined. Moreover, the changes of the pore pressure and seepage force induced by pumping and recharge will also result in significant horizontal deformations in the strata near the recharge wells.

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

Saller, A.H.; Schlanger, S.O.

Two wells drilled along the margin of Enewetak Atoll penetrated approximately 1000 m of upper Eocene, Oligocene, and lower Miocene carbonates. Strontium isotope stratigraphy indicates relatively continuous deposition of carbonate from 40 Ma to 20 Ma. Depositional environments show a gradual basinward progradation of facies with slope carbonates passing upward into fore-reef, reef, back-reef, and lagoonal carbonates. Slope strata contain wackestones and packstones with submarine-cemented lithoclasts, coral, coralline algae fragments, benthic rotaline forams, planktonic forams, and echinoderm fragments. Fore-reef strata are dominantly packstones and boundstones containing large pieces of coral, abundant benthic forams, coralline algae fragments, stromatoporoids( ), and minormore » planktonic forams. Reef and near-reef sediments include coralgal boundstones and grainstones with abundant benthic forams. Halimeda and miliolid forams are common in lagoonward parts of the back reef. Sponge borings, geopetal structures, and fractures are common in reef and fore-reef strata. Lagoonal strata are wackestones and packstones with common mollusks, coral, coralline algae, and benthic forams (rotaline and miliolid). Diagenesis has extensively altered strata near the atoll margin. Aragonite dissolution and calcite cements (radiaxial and cloudy prismatic) are abundant in fore-reef, reef, and some back-reef strata. Petrographic and geochemical data indicate aragonite dissolution and calcite cementation in seawater at burial depths of 100 to 300 m. Dolomite occurs in slope and deeply buried reefal carbonates. Most dolomitization occurred at burial depths of more than 1000 m in cool marine waters circulating through the atoll. lagoonal strata are not significantly altered by marine diagenesis and still contain abundant primary aragonite and magnesium calcite.« less

Downslope coarsening in aeolian grainflows of the Navajo Sandstone

NASA Astrophysics Data System (ADS)

Loope, David B.; Elder, James F.; Sweeney, Mark R.

2012-07-01

Downslope coarsening in grainflows has been observed on present-day dunes and generated in labs, but few previous studies have examined vertical sorting in ancient aeolian grainflows. We studied the grainflow strata of the Jurassic Navajo Sandstone in the southern Utah portion of its outcrop belt from Zion National Park (west) to Coyote Buttes and The Dive (east). At each study site, thick sets of grainflow-dominated cross-strata that were deposited by large transverse dunes comprise the bulk of the Navajo Sandstone. We studied three stratigraphic columns, one per site, composed almost exclusively of aeolian cross-strata. For each column, samples were obtained from one grainflow stratum in each consecutive set of the column, for a total of 139 samples from thirty-two sets of cross-strata. To investigate grading perpendicular to bedding within individual grainflows, we collected fourteen samples from four superimposed grainflow strata at The Dive. Samples were analyzed with a Malvern Mastersizer 2000 laser diffraction particle analyser. The median grain size of grainflow samples ranges from fine sand (164 μm) to coarse sand (617 μm). Using Folk and Ward criteria, samples are well-sorted to moderately-well-sorted. All but one of the twenty-eight sets showed at least slight downslope coarsening, but in general, downslope coarsening was not as well-developed or as consistent as that reported in laboratory subaqueous grainflows. Because coarse sand should be quickly sequestered within preserved cross-strata when bedforms climb, grain-size studies may help to test hypotheses for the stacking of sets of cross-strata.

Rapid Shifts in Soil Nutrients and Decomposition Enzyme Activity in Early Succession Following Forest Fire

DOE PAGES

Knelman, Joseph E.; Graham, Emily B.; Ferrenberg, Scott; ...

2017-09-15

In post-disturbance landscapes nutrient availability has proven a major control on ecological succession. In this study, we examined variation in connections between soil nutrient availability and decomposition extracellular enzyme activity (EEA) across post fire secondary succession in forest soils as well as after a secondary flood disturbance. We also examined possible linkages between edaphic properties and bacterial communities based on 16S rRNA gene analysis. We found that with advancing succession in a post-fire landscape, the relationship between soil nutrients and EEA became stronger over time. In general, late successional soils showed stronger connections between EEA and soil nutrient status, whilemore » early successional soils were marked by a complete decoupling of nutrients and EEA. We also found that soil moisture and bacterial communities of post-fire disturbance soils were susceptible to change following the secondary flood disturbance, while undisturbed, reference forest soils were not. Our results demonstrate that nutrient pools correlating with EEA change over time. While past work has largely focused on ecosystem succession on decadal timescales, our work suggests that nutrients shift in their relative importance as a control of decomposition EEA in the earliest stages of secondary succession. Furthermore, this work emphasizes the relevance of successional stage, even on short timescales, in predicting rates of carbon and nitrogen cycling, especially as disturbances become more frequent in a rapidly changing world.« less

Rapid Shifts in Soil Nutrients and Decomposition Enzyme Activity in Early Succession Following Forest Fire

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

Knelman, Joseph E.; Graham, Emily B.; Ferrenberg, Scott

In post-disturbance landscapes nutrient availability has proven a major control on ecological succession. In this study, we examined variation in connections between soil nutrient availability and decomposition extracellular enzyme activity (EEA) across post fire secondary succession in forest soils as well as after a secondary flood disturbance. We also examined possible linkages between edaphic properties and bacterial communities based on 16S rRNA gene analysis. We found that with advancing succession in a post-fire landscape, the relationship between soil nutrients and EEA became stronger over time. In general, late successional soils showed stronger connections between EEA and soil nutrient status, whilemore » early successional soils were marked by a complete decoupling of nutrients and EEA. We also found that soil moisture and bacterial communities of post-fire disturbance soils were susceptible to change following the secondary flood disturbance, while undisturbed, reference forest soils were not. Our results demonstrate that nutrient pools correlating with EEA change over time. While past work has largely focused on ecosystem succession on decadal timescales, our work suggests that nutrients shift in their relative importance as a control of decomposition EEA in the earliest stages of secondary succession. Furthermore, this work emphasizes the relevance of successional stage, even on short timescales, in predicting rates of carbon and nitrogen cycling, especially as disturbances become more frequent in a rapidly changing world.« less

Spatial distribution of soil properties on a landslide in Taiwan: effects of movement types and vegetation

NASA Astrophysics Data System (ADS)

Lee, Pei-Chen; Cheng, Chih-Hsin

2017-04-01

Landslides are critical natural disturbances in tropical and temperate areas and exert immense impacts on forest ecosystems and soil properties. The impacts of landslides on soil properties not only vary with their movement type, scale, or location but also have great spatial variation inside landslide. In this study, the effects of movement type (erosion and deposition) and succeeding vegetation on soil properties inside a landslide scar were evaluated. The study site was located in Chiufenernshan, central Taiwan. The landslide was triggered by the Chi-Chi Earthquake (Ritch magnitude 7.3) in 1999. A huge amount of waste debris (30 million m3) was moved along the sliding slope (with a tipping degree at 26o) and deposited in the lower parts. Total area size of landslide scar was 200 ha and about 30 - 50 m depth waste material was eroded/deposited in the upper/lower scar areas. After 17 years, the succeeding vegetation varied inside landslide scar. The erosion areas were covered with grass (Miscanthus floridulus) or left barren in some slopes. In contrast, a secondary forest, dominated with Trema orientalis, Lithocarpus konishii, Mallotus paniculatus, and Smilax bracteata, developed in the deposition areas. We collected soil samples in different landscape areas including (i) erosion areas without vegetation, (ii) erosion areas with grass vegetation, (iii) deposition areas, and (iv) adjacent undisturbed areas. Our results indicated that the erosion areas had higher bulk density, rock fragment and pH value, but less soil organic carbon, total nitrogen, total phosphorus and N-mineralization rate than both deposition and adjacent undisturbed areas. The soil properties without vegetation even showed the extreme end compared to the soils with grass vegetation. Soils at the deposition zone had similar rock fragment, bulk density, soil pH, soil organic carbon and N-mineralization rate values to the undisturbed site (p > 0.05). We speculate that movement types could determine the initial establishment of vegetation types and then influence soil properties under vegetation succession. Therefore, both waste movement types and vegetation and their interactions play important roles on soil properties.

Inventory of Neoproterozoic and Paleozoic strata in Sonora, Mexico

USGS Publications Warehouse

Stewart, John H.; Poole, Forrest G.

2002-01-01

This compilation is an inventory of all known outcrops of Neoproterozoic and Paleozoic strata in Sonora, Mexico. We have not attempted an interpretation of the regional stratigraphic or structural setting of the strata. Brief summaries of the stratigraphic setting of the Sonora rocks are given in Poole and Hayes (1971), Rangin (1978), Stewart and others (1984, 1990), and Poole and Madrid (1986; 1988b). More specific information on the setting of strata of specific ages are given by Stewart and others (2002) for the Neoproterozoic and Cambrian; by Poole and others (1995a) for Ordovician shelf strata; by Poole and others (1995b) for Ordovician deep-water openbasin strata; by Poole and others (1997, 1998, 2000a) for Silurian strata; and by Poole and others (2000a) for Mississippian strata. Other reports that discuss regional aspects of Paleozoic stratigraphy include López-Ramos (1982), Peiffer-Rangin, (1979, 1988), Pérez-Ramos (1992), and Stewart and others (1997, 1999a). Structurally, the major Paleozoic feature of Sonora is the Sonora allochthon, consisting of deep-water (eugeoclinal) strata emplaced in the Permian over shelf (miogeoclinal) deposits (Poole and others, 1995a,b; Poole and Perry, 1997; 1998). The emplacement structure is generally considered to be a major Permian continental margin thrust fault that emplaced the deep-water rocks northward over shelf (miogeoclinal) deposits. An alternate interpretation has been presented by Stewart and others (2002). He proposed that the emplacement of the Sonora allochthon was along a major Permian transpressional structure that was primarily a strike-slip fault with only a minor thrust component . The Mojave-Sonora megashear has been proposed to disrupt Neoproterozoic and Paleozoic trends in Sonora. This feature is a hypothetical, left-lateral, northwest-striking fault extending across northern Sonora and the southwestern United States (Silver and Anderson, 1974; Anderson and Schmidt, 1983). It is proposed to have Jurassic displacements of about 700-800 km. Current opinion is mixed concerning whether the Mojave-Sonora megashear exists (see discussions and references in Stewart and others, 1990; 1999a). The inventory presented here is the product of a search of the literature for described Neoproterozoic and Paleozoic localities and our examination of a large number of the outcrops in the field. The individual localities are described by reference letters and numbers, locality name, latitude and longitude, a brief text on the stratigraphy of the strata, and references. Figure 1 is an index showing the location of Sonora and the location of figure 2. The location of a few localites that are outside of figure 2 are also shown on figure 1. We also include a separate description of localities that have been erroneously reported, on the based of our field examinations, to contain Neoproterozoic and Paleozoic rocks. We include a brief description of problematic strata in southern Sonora that have been described as Paleozoic, but may be at least in part Mesozoic. Figures 3-11 show the distribution of Neoproterozoic, Cambrian, Ordovician, Silurian, Devonian, Mississippian, Pennsylvanian, and Permian strata in Sonora.

A Systems Approach to Identifying Exploration and Development Opportunities in the Illinois Basin: Digital Portifolio of Plays in Underexplored Lower Paleozoic Rocks [Part 1 of 2

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

Seyler, Beverly; Harris, David; Keith, Brian

2008-06-30

This study examined petroleum occurrence in Ordovician, Silurian and Devonian reservoirs in the Illinois Basin. Results from this project show that there is excellent potential for additional discovery of petroleum reservoirs in these formations. Numerous exploration targets and exploration strategies were identified that can be used to increase production from these underexplored strata. Some of the challenges to exploration of deeper strata include the lack of subsurface data, lack of understanding of regional facies changes, lack of understanding the role of diagenetic alteration in developing reservoir porosity and permeability, the shifting of structural closures with depth, overlooking potential producing horizons,more » and under utilization of 3D seismic techniques. This study has shown many areas are prospective for additional discoveries in lower Paleozoic strata in the Illinois Basin. This project implemented a systematic basin analysis approach that is expected to encourage exploration for petroleum in lower Paleozoic rocks of the Illinois Basin. The study has compiled and presented a broad base of information and knowledge needed by independent oil companies to pursue the development of exploration prospects in overlooked, deeper play horizons in the Illinois Basin. Available geologic data relevant for the exploration and development of petroleum reservoirs in the Illinois Basin was analyzed and assimilated into a coherent, easily accessible digital play portfolio. The primary focus of this project was on case studies of existing reservoirs in Devonian, Silurian, and Ordovician strata and the application of knowledge gained to future exploration and development in these underexplored strata of the Illinois Basin. In addition, a review of published reports and exploration in the New Albany Shale Group, a Devonian black shale source rock, in Illinois was completed due to the recent increased interest in Devonian black shales across the United States. The New Albany Shale is regarded as the source rock for petroleum in Silurian and younger strata in the Illinois Basin and has potential as a petroleum reservoir. Field studies of reservoirs in Devonian strata such as the Geneva Dolomite, Dutch Creek Sandstone and Grassy knob Chert suggest that there is much additional potential for expanding these plays beyond their current limits. These studies also suggest the potential for the discovery of additional plays using stratigraphic concepts to develop a subcrop play on the subkaskaskia unconformity boundary that separates lower Devonian strata from middle Devonian strata in portions of the basin. The lateral transition from Geneva Dolomite to Dutch Creek Sandstone also offers an avenue for developing exploration strategies in middle Devonian strata. Study of lower Devonian strata in the Sesser Oil Field and the region surrounding the field shows opportunities for development of a subcrop play where lower Devonian strata unconformably overlie Silurian strata. Field studies of Silurian reservoirs along the Sangamon Arch show that opportunities exist for overlooked pays in areas where wells do not penetrate deep enough to test all reservoir intervals in Niagaran rocks. Mapping of Silurian reservoirs in the Mt. Auburn trend along the Sangamon Arch shows that porous reservoir rock grades laterally to non-reservoir facies and several reservoir intervals may be encountered in the Silurian with numerous exploration wells testing only the uppermost reservoir intervals. Mapping of the Ordovician Trenton and shallower strata at Centralia Field show that the crest of the anticline shifted through geologic time. This study illustrates that the axes of anticlines may shift with depth and shallow structure maps may not accurately predict structurally favorable reservoir locations at depth.« less

Application of deterministic deconvolution of ground-penetrating radar data in a study of carbonate strata

USGS Publications Warehouse

Xia, J.; Franseen, E.K.; Miller, R.D.; Weis, T.V.

2004-01-01

We successfully applied deterministic deconvolution to real ground-penetrating radar (GPR) data by using the source wavelet that was generated in and transmitted through air as the operator. The GPR data were collected with 400-MHz antennas on a bench adjacent to a cleanly exposed quarry face. The quarry site is characterized by horizontally bedded carbonate strata with shale partings. In order to provide groundtruth for this deconvolution approach, 23 conductive rods were drilled into the quarry face at key locations. The steel rods provided critical information for: (1) correlation between reflections on GPR data and geologic features exposed in the quarry face, (2) GPR resolution limits, (3) accuracy of velocities calculated from common midpoint data and (4) identifying any multiples. Comparing the results of deconvolved data with non-deconvolved data demonstrates the effectiveness of deterministic deconvolution in low dielectric-loss media for increased accuracy of velocity models (improved at least 10-15% in our study after deterministic deconvolution), increased vertical and horizontal resolution of specific geologic features and more accurate representation of geologic features as confirmed from detailed study of the adjacent quarry wall. ?? 2004 Elsevier B.V. All rights reserved.

Holocene alluvial stratigraphy and response to climate change in the Roaring River valley, Front Range, Colorado, USA

USGS Publications Warehouse

Madole, Richard F.

2012-01-01

Stratigraphic analyses and radiocarbon geochronology of alluvial deposits exposed along the Roaring River, Colorado, lead to three principal conclusions: (1) the opinion that stream channels in the higher parts of the Front Range are relics of the Pleistocene and nonalluvial under the present climate, as argued in a water-rights trial USA v. Colorado, is untenable, (2) beds of clast-supported gravel alternate in vertical succession with beds of fine-grained sediment (sand, mud, and peat) in response to centennial-scale changes in snowmelt-driven peak discharges, and (3) alluvial strata provide information about Holocene climate history that complements the history provided by cirque moraines, periglacial deposits, and paleontological data. Most alluvial strata are of late Holocene age and record, among other things, that: (1) the largest peak flows since the end of the Pleistocene occurred during the late Holocene; (2) the occurrence of a mid- to late Holocene interval (~2450–1630(?) cal yr BP) of warmer climate, which is not clearly identified in palynological records; and (3) the Little Ice Age climate seems to have had little impact on stream channels, except perhaps for minor (~1 m) incision. Published

Holocene alluvial stratigraphy and response to climate change in the Roaring River valley, Front Range, Colorado, USA

NASA Astrophysics Data System (ADS)

Madole, Richard F.

2012-09-01

Stratigraphic analyses and radiocarbon geochronology of alluvial deposits exposed along the Roaring River, Colorado, lead to three principal conclusions: (1) the opinion that stream channels in the higher parts of the Front Range are relics of the Pleistocene and nonalluvial under the present climate, as argued in a water-rights trial USA v. Colorado, is untenable, (2) beds of clast-supported gravel alternate in vertical succession with beds of fine-grained sediment (sand, mud, and peat) in response to centennial-scale changes in snowmelt-driven peak discharges, and (3) alluvial strata provide information about Holocene climate history that complements the history provided by cirque moraines, periglacial deposits, and paleontological data. Most alluvial strata are of late Holocene age and record, among other things, that: (1) the largest peak flows since the end of the Pleistocene occurred during the late Holocene; (2) the occurrence of a mid- to late Holocene interval (~ 2450-1630(?) cal yr BP) of warmer climate, which is not clearly identified in palynological records; and (3) the Little Ice Age climate seems to have had little impact on stream channels, except perhaps for minor (~ 1 m) incision.

Elsaesser variable analysis of fluctuations in the ion foreshock and undisturbed solar wind

NASA Technical Reports Server (NTRS)

Labelle, James; Treumann, Rudolf A.; Marsch, Eckart

1994-01-01

Magnetohydrodynamics (MHD) fluctuations in the solar wind have been investigated previously by use of Elsaesser variables. In this paper, we present a comparison of the spectra of Elsaesser variables in the undisturbed solar wind at 1 AU and in the ion foreshock in front of the Earth. Both observations take place under relatively strong solar wind flow speed conditions (approximately equal 600 km/s). In the undisturbed solar wind we find that outward propagating Alfven waves dominate, as reported by other observers. In the ion foreshock the situation is more complex, with neither outward nor inward propagation dominating over the entire range investigated (1-10 mHz). Measurements of the Poynting vectors associated with the fluctuations are consistent with the Elsaesser variable analysis. These results generally support interpretations of the Elsaesser variables which have been made based strictly on solar wind data and provide additional insight into the nature of the ion foreshock turbulence.

Phase II study of the PI3K inhibitor BKM120 in patients with advanced or recurrent endometrial carcinoma: a stratified type I–type II study from the GINECO group

PubMed Central

Heudel, P-E; Fabbro, M; Roemer-Becuwe, C; Kaminsky, M C; Arnaud, A; Joly, F; Roche-Forestier, S; Meunier, J; Foa, C; You, B; Priou, F; Tazi, Y; Floquet, A; Selle, F; Berton-Rigaud, D; Lesoin, A; Kalbacher, E; Lortholary, A; Favier, L; Treilleux, I; Ray-Coquard, I

2017-01-01

Backround: Patients with metastatic endometrial carcinoma have a poor prognosis and PIK3CA mutations and amplifications are common in these cancers. This study evaluated the efficacy and safety of the pure PI3K inhibitor BKM120 in advanced or recurrent endometrial carcinoma. Methods: This phase II, multicentre, single-arm, double strata (histological low grade (LG) or high grade (HG)) open-label study enrolled patients with histologically confirmed advanced or recurrent endometrial carcinoma who had received not more than one prior chemotherapy regimen. Patients received initially BKM120 100 mg tablets once daily. Primary end points were proportion of patients free of progression at 2 months (HG strata) or at 3 months (LG strata), objective response rate (ORR), and safety. Results: A total of 40 patients were enrolled, of whom 16 patients had received BKM120 at 100 mg. Because of high toxicities (cutaneous rash (54%), depressive events (47%), and anxiety (40%), the IDMC has proposed to stop recruitment at 100 mg and to continue the clinical trial with a lower dose of 60 mg per day. In addition, 24 patients (median age 67 years old) were newly enrolled (14 in the LG strata and 10 in the HG strata). Rate of nonprogression at 2 months in the HG strata was 70% and at 3 months was 60% in the LG strata. Median progression-free survival (PFS) for all patients is 4.5 months (CI 95% 2.8–6.1), and the median PFS for LG strata is 8.3 months compared with 3.8 months for the HG strata. No response was reported. At 60 mg per day, the most commonly reported treatment-related adverse events (AEs) were hyperglycaemia (58%), cognitive (31%), digestive (28%), hepatic liver functions (26%), and rash (23%). The most commonly reported treatment-related grade ⩾3 AEs were HTA (17%), hyperglycaemia (17%), and increased alanine aminotransferase (24%). Five patients (21%) stopped BKM120 for toxicity. Conclusions: The BKM120 was associated with an unfavourable safety profile and minimal antitumour activity in monotherapy in advanced or recurrent endometrial carcinoma. The clinical trial was stopped before end of recruitment for toxicity. PMID:28072765

[Objective and subjective knowledge of HIV/AIDS as predictor of condom use in adolescents].

PubMed

Villaseñor-Sierra, Alberto; Caballero-Hoyos, Ramiro; Hidalgo-San Martín, Alfredo; Santos-Preciado, José Ignacio

2003-01-01

To evaluate the association between objective and subjective knowledge on HIV/AIDS and condom use. Analysis of a database from an anonymous, self-applied, randomized survey conducted between 1995 and 1996. Study subjects were 1,410 adolescents of four socioeconomic strata from Guadalajara, Mexico. Objective knowledge was assessed with 24 questions regarding HIV/AIDS, and subjective knowledge with the question "how much do you think you know about HIV/AIDS?" The variables associated with condom use were identified using logistic regression analysis and by calculating odds ratios with a 95% confidence interval. The degree of objective knowledge was "average", differentiated by socioeconomic strata (p < 0.001), and was higher in adolescents from medium and high socioeconomic strata (p < 0.008). Regarding subjective knowledge, adolescents from the low, medium, and high socioeconomic strata claimed to know "a little", and the ones from the lowest stratum claimed to know "very little". Condom use was higher in males (35.4%), and in adolescents from high socioeconomic strata (p < 0.005), than in females (15.3%) (p < 0.001). Although there was a correlation between objective and subjective knowledge (r = 0.37, p < 0.001), a higher degree of subjective knowledge was associated with condom use (p < 0.001). Subjective knowledge, belonging to medium and high socioeconomic strata and being male, were predictors of condom use.

The Basal Ediacaran Noonday Formation, Eastern California, and implications for Laurentian equivalents

NASA Astrophysics Data System (ADS)

Petterson, R.; Prave, A. R.; Wernicke, B. P.

2009-12-01

The Neoproterozoic-Cambrian succession in the Death Valley region of SW Laurentia is among the best exposed and easily accessible in the world, and comprises one of the most complete sections in Laurentia. The largest single exposure of these strata occurs in the Panamint Range on the west flank of Death Valley, but this area has received little attention in comparison to exposures to the east of Death Valley, primarily because of structural complexity and metamorphism. The eastern strata, though unmetamorphosed, occur in isolated fault-bounded exposures and are relatively incomplete compared to the Panamint stratigraphy. This, combined with a lack of fossil or radiometric age control, has hindered confident regional correlation, as well as placement in the context of hallmark Neoproterozoic events observed in other successions around the globe. New mapping, measured sections and high-resolution C-isotope data reported here from the Noonday Formation in the Panamints delineate its regional stratigraphic architecture and establish its age through correlation with sections with radiometric age control. Carbon isotopic trends in the Panamints match to within 1-2‰ reproducibility previous results obtained for correlative strata in the eastern sections, indicating that metamorphism did not significantly alter C isotopic ratios. The combined litho- and chemostratigraphic data form the basis for a revised stratigraphic framework for the Noonday Formation. A composite section shows that, where most complete, the Noonday consists of three members, from the base upward, the Sentinel Peak, Radcliff, and Mahogany Flats members. New mapping and chemostratigraphic data permit robust regional correlation of a thin dolostone marker horizon at the base of the Noonday in the Panamints as little as 2 m thick (Sentinel Peak Member) with a tube-bearing microbial dolostone in the eastern Death Valley region more than 200 m thick. The data also reveal that the Radcliff Member is bounded by disconformable surfaces and their correlative conformities. These surfaces are recognizable throughout the region and are used to construct a regionally unified stratigraphic nomenclature. We present a chemostratigraphic profile spanning most of Noonday time. The profile is a remarkable match for the Maiberg cap carbonate sequence in Namibia, including the decline to a minimum at -5‰, a recovery to near 0‰, and then subsequent decline to 2‰. Correlation of these curves (1) firmly places the Noonday at the base of the Ediacaran Period, (2) indicates deposition of ~200 m of Sentinel Peak and Radcliff strata occurred between 635 and 632 Ma, (3) supports the hypothesis that the Wildrose Diamictite of the Kingston Peak Formation, which lies in sharp contact below the Sentinel Peak Member, represents at least part of the Marinoan glacial interval; (4) helps identify correlative cap carbonate sequences in key Laurentian sections, which include the Ravensthroat Formation in the MacKenzie Mountains, dolostones capping the upper diamictite of the Pocatello Formation in eastern Idaho, and the middle part of the Mina el Mezquite Formation in Sonora.

Migrated hydrocarbons in exposure of Maastrichtian nonmarine strata near Saddle Mountain, lower Cook Inlet, Alaska

USGS Publications Warehouse

LePain, D.L.; Lillis, P.G.; Helmold, K.P.; Stanley, R.G.

2012-01-01

Magoon and others (1980) described an 83-meter- (272-foot-) thick succession of Maastrichtian (Upper Cretaceous) conglomerate, sandstone, mudstone, and coal exposed on the south side of an unnamed drainage, approximately 3 kilometers (1.8 miles) east of Saddle Mountain in lower Cook Inlet (figs. 1 and 2). The initial significance of this exposure was that it was the first reported occurrence of nonmarine rocks of this age in outcrop in lower Cook Inlet, which helped constrain the Late Cretaceous paleogeography of the area and provided important information on the composition of latest Mesozoic sandstones in the basin. The Saddle Mountain section is thought to be an outcrop analog for Upper Cretaceous nonmarine strata penetrated in the OCS Y-0097 #1 (Raven) well, located approximately 40 kilometers (25 miles) to the south–southeast in Federal waters (fig. 1). Atlantic Richfield Company (ARCO) drilled the Raven well in 1980 and encountered oil-stained rocks and moveable liquid hydrocarbons between the depths of 1,760 and 3,700 feet. Completion reports on file with the Bureau of Ocean Energy Management (BOEM; formerly Bureau of Ocean Energy Management, Regulation and Enforcement, and prior to 2010, U.S. Minerals Management Service) either show flow rates of zero or do not mention flow rates. A fluid analysis report on file with BOEM suggests that a wireline tool sampled some oil beneath a 2,010-foot diesel cushion during the fl ow test of the 3,145–3,175 foot interval, but the recorded fl ow rate was still zero (Kirk Sherwood, written commun., January 9, 2012). Further delineation and evaluation of the apparent accumulation was never performed and the well was plugged and abandoned. As part of a 5-year comprehensive evaluation of the geology and petroleum systems of the Cook Inlet forearc basin, the Alaska Division of Geological & Geophysical Surveys obtained a research permit from the National Park Service to access the relatively poorly understood ‘Saddle Mountain exposure’ that is located in the Lake Clark National Park and Preserve. This work was done in cooperation with the Alaska Division of Oil & Gas and U.S. Geological Survey (USGS) research geologists. This report expands on Magoon and others’ (1980) description of the exposure, presents new data on sandstone composition and reservoir quality, presents new geochemical data on petroleum extracted from the outcropping sandstone, and describes oil-bearing correlative strata penetrated by the Raven well. Although the exposure is more than a kilometer (0.6 mile) east of Saddle Mountain (fig. 2), in this report we variously refer to it as the Saddle Mountain succession, Saddle Mountain section, or the rocks at Saddle Mountain underlain by Upper Jurassic strata of the Naknek Formation.

Mobility of radionuclides and trace elements in soil from legacy NORM and undisturbed naturally 232Th-rich sites.

PubMed

Mrdakovic Popic, Jelena; Meland, Sondre; Salbu, Brit; Skipperud, Lindis

2014-05-01

Investigation of radionuclides (232Th and 238U) and trace elements (Cr, As and Pb) in soil from two legacy NORM (former mining sites) and one undisturbed naturally 232Th-rich site was conducted as a part of the ongoing environmental impact assessment in the Fen Complex area (Norway). The major objectives were to determine the radionuclide and trace element distribution and mobility in soils as well as to analyze possible differences between legacy NORM and surrounding undisturbed naturally 232Th-rich soils. Inhomogeneous soil distribution of radionuclides and trace elements was observed for each of the investigated sites. The concentration of 232Th was high (up to 1685 mg kg(-1), i.e., ∼7000 Bq kg(-1)) and exceeded the screening value for the radioactive waste material in Norway (1 Bq g(-1)). Based on the sequential extraction results, the majority of 232Th and trace elements were rather inert, irreversibly bound to soil. Uranium was found to be potentially more mobile, as it was associated with pH-sensitive soil phases, redox-sensitive amorphous soil phases and soil organic compounds. Comparison of the sequential extraction datasets from the three investigated sites revealed increased mobility of all analyzed elements at the legacy NORM sites in comparison with the undisturbed 232Th-rich site. Similarly, the distribution coefficients Kd (232Th) and Kd (238U) suggested elevated dissolution, mobility and transportation at the legacy NORM sites, especially at the decommissioned Nb-mining site (346 and 100 L kg(-1) for 232Th and 238U, respectively), while the higher sorption of radionuclides was demonstrated at the undisturbed 232Th-rich site (10,672 and 506 L kg(-1) for 232Th and 238U, respectively). In general, although the concentration ranges of radionuclides and trace elements were similarly wide both at the legacy NORM and at the undisturbed 232Th-rich sites, the results of soil sequential extractions together with Kd values supported the expected differences between sites as the consequences of previous mining operations. Hence, mobility and possible elevated bioavailability at the legacy NORM site could be expected and further risk assessment should take this into account when decisions about the possible intervention measures are made.

Discriminating Natural Variation from Legacies of Disturbance in Semi-Arid Forests, Southwestern USA

NASA Astrophysics Data System (ADS)

Swetnam, T. L.; Lynch, A. M.; Falk, D. A.; Yool, S. R.; Guertin, D. P.

2014-12-01

Characterizing differences in existing vegetation driven by natural variation versus disturbance legacies could become a critical component of applied forest management practice with important implications for monitoring ecologic succession and eco-hydrological interactions within the critical zone. Here we characterize variations in aerial LiDAR derived forest structure at individual tree scale in Arizona and New Mexico. Differences in structure result from both topographic and climatological variations and from natural and human related disturbances. We chose a priori undisturbed and disturbed sites that included preservation, development, logging and wildfire as exemplars. We compare two topographic indices, the topographic position index (TPI) and topographic wetness index (TWI), to two local indicators of spatial association (LISA): the Getis-Ord Gi and Anselin's Moran I. We found TPI and TWI correlate well to positive z-scores (tall trees in tall neighborhoods) in undisturbed areas and that disturbed areas are clearly defined by negative z-scores, in some cases better than what is visible from traditional orthophotography and existing GIS maps. These LISA methods also serve as a robust technique for creating like-clustered stands, i.e. common stands used in forest inventory monitoring. This research provides a significant advancement in the ability to (1) quantity variation in forest structure across topographically complex landscapes, (2) identify and map previously unrecorded disturbance locations, and (3) quantify the different impacts of disturbance within the perimeter of a stand or event at ecologically relevant scale.

Reconnaissance observations of long-term natural vegetation recovery in the Cape Thompson region, Alaska, and additions to the checklist of flora

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

Everett, K.R.; Murray, B.M.; Murray, D.F.

1985-06-01

The diversity of disturbance types, landforms, vegetation and soils, together with the large, well-documented flora, makes Cape Thompson an ideal site to study long-term (20-year) environmental adjustments after impact. Man-caused disturbances there between 1958 and 1962 fall into three categories: runways, excavations and off-road vehicle trails. In addition, natural disturbance by frost action creates scars. Reestablished vegetation after 20 years consisted of species found in adjacent undisturbed landscapes. Vegetation on excavations and cut-and-fill surfaces consisted of 3 to 5% vascular plants, of which Deschampsia cespitosa and Sagina nivalis are the most important (in terms of cover and frequency) of themore » 33 species identified. Cryptogams generally made up less than 1% of the vegetation, with lichens showing the least reestablishment. Vehicle trails crossing both alkaline and acidic fell-fields are still visible. Dryas octopetala, dominant in the adjacent undisturbed tundra, has not been effective in either recolonizing the track areas or extending into the trail from either the center or sides. The tundra at Ogotoruk Creek has shown considerable resiliency in terms of reestablishment of vegetation, especially in the moister sites where bank slumping and lateral migration of vegetation is effective. On the more-exposed, better-drained sites, as on frost scars, the continuing interplay between physical and biological forces has prevented directional or progressive plant succession. 33 figs., 13 tabs.« less

The importance of subsurface geology for water source and vegetation communities in Cherokee Marsh, Wisconsin

USGS Publications Warehouse

Kurtz, A.M.; Bahr, J.M.; Carpenter, Q.J.; Hunt, R.J.

2007-01-01

Restoration of disturbed wetland systems is an important component of wetland mitigation, yet uncertainty remains about how hydrologic processes affect biologic processes and wetlands patterns. To design more effective restoration strategies and re-establish native plant communities in disturbed wetlands, it is imperative to understand undisturbed systems. A site within Cherokee Marsh located in Madison, Wisconsin, USA, contains a relatively undisturbed area of wetland consisting of plant communities common within the prairie landscape including a fen, sedge meadow, and shallow marsh. These distinct communities are found within an area of minimal topographic relief, yet transitions from one community to the next occur over short distances. This study sought to characterize the geologic, hydrologic, and chemical gradients associated with these shifts in vegetation to gain insight into the factors controlling the spatial differences in dominant plant species, which could be critical for restoration success. Vegetation analyses revealed a transition of dominant sedge species, which appeared to correspond to changes in hydrology from a ground-water dominated to a surface-water dominated system (as determined by water isotopes). Along the same vegetation transect, subsurface coring results show a heterogeneous composition of peat and till with lateral and vertical variations in stratigraphy, which relates to variability in ground-water discharge as evidenced by hydroperiods and stable isotope composition. Applications of this type of approach throughout the glaciated terrains of the midwestern and northeastern United States and Canada can improve future wetland restoration and management. ?? 2007, The Society of Wetland Scientists.

Hydrologic regime controls soil phosphorus fluxes in restoration and undisturbed wetlands

USGS Publications Warehouse

Aldous, A.; McCormick, P.; Ferguson, C.; Graham, S.; Craft, C.

2005-01-01

Many wetland restoration projects occur on former agricultural soils that have a history of disturbance and fertilization, making them prone to phosphorus (P) release upon flooding. To study the relationship between P release and hydrologic regime, we collected soil cores from three restoration wetlands and three undisturbed wetlands around Upper Klamath Lake in southern Oregon, U.S.A. Soil cores were subjected to one of three hydrologic regimes - flooded, moist, and dry - for 7.5 weeks, and P fluxes were measured upon reflooding. Soils from restoration wetlands released P upon reflooding regardless of the hydrologic regime, with the greatest releases coming from soils that had been flooded or dried. Undisturbed wetland soils released P only after drying. Patterns in P release can be explained by a combination of physical and biological processes, including the release of iron-bound P due to anoxia in the flooded treatment and the mineralization of organic P under aerobic conditions in the dry treatment. Higher rates of soil P release from restoration wetland soils, particularly under flooded conditions, were associated with higher total P concentrations compared with undisturbed wetland soils. We conclude that maintaining moist soil is the means to minimize P release from recently flooded wetland soils. Alternatively, prolonged flooding provides a means of liberating excess labile P from former agricultural soils while minimizing continued organic P mineralization and soil subsidence. ?? 2005 Society for Ecological Restoration International.

[Monitoring and analysis on evolution process of rainfall runoff water quality in urban area].

PubMed

Dong, Wen; Li, Huai-En; Li, Jia-Ke

2013-02-01

In order to find the water quality evolution law and pollution characteristics of the rainfall runoff from undisturbed to the neighborhood exit, 6 times evolution process of rainfall runoff water quality were monitored and analyzed from July to October in 2011, and contrasted the clarification efficiency of the grassland to the roof runoff rudimentarily at the same time. The research showed: 1. the results of the comparison from "undisturbed, rainfall-roof, rainfall runoff-road, rainfall-runoff the neighborhood exit runoff " showed that the water quality of the undisturbed rain was better than that from the roof and the neighborhood exist, but the road rainfall runoff water quality was the worst; 2. the average concentrations of the parameters such as COD, ammonia nitrogen and total nitrogen all exceeded the Fifth Class of the Surface Water Quality Standard except for the soluble total phosphorus from undisturbed rainfall to the neighborhood exit; 3. the runoff water quality of the short early fine days was better than that of long early fine days, and the last runoff water quality was better than that of the initial runoff in the same rainfall process; 4. the concentration reduction of the grassland was notable, and the reduction rate of the grassland which is 1.0 meter wide of the roof runoff pollutants such as COD and nitrogen reached 30%.

Calaveras reversed: westward younging is indicated.

USGS Publications Warehouse

Bateman, P.C.; Harris, A.G.; Kistler, R.W.; Krauskopf, K.B.

1985-01-01

Samples of limestone collected from strata in the southern part of the western metamorphic belt of the Sierra Nevada, which traditionally have been assigned to the Calaveras Formation, have yielded Early Triassic conodonts, and samples of metavolcanic rock indicate an Early Jurassic Rb-Sr age. These ages, together with general westward younging of units rather than with eastward younging as has been assumed until recently by many workers, chiefly on the basis of sparse oservations of bedding facings. The rocks are strongly deformed, and the possibility that tectonism rather than stratigraphic succession accounts for the age pattern cannot be dismissed.-Authors

Geology and paleontology of the Santa Maria district, California

USGS Publications Warehouse

Woodring, W.P.; Bramlette, M.N.

1950-01-01

Among areas of possible interest, three appear to be favorable for prospecting on the basis of surface geology: an area east of Foxen Canyon, where oil may be trapped in the basal part of the Tinaquaic sandstone member of the Sisquoc formation by westward overlap of successively higher Tinaquaic strata onto the Monterey shale; an area so1tth of the I ... ions Head fault, where oil may be trapped by the fault; and the offshore extension of the north border of Point Sal Ridge, where oil may possibly be trapped in the Monterey by overlap of the Sisquoc formation.

Application of ground-penetrating radar at McMurdo Station, Antarctica

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

Stefano, J.E.

1992-05-01

Argonne National Laboratory initiated a site investigation program at McMurdo Station, Antarctica, to characterize environmental contamination. The performance and usefulness of ground-penetrating radar (GPR) was evaluated under antarctic conditions during the initial site investigation in January 1991. Preliminary surveys were successful in defining the contact between reworked pyroclastic material and in the prefill, undisturbed pyroclastics and basalts at some sites. Interference from radio traffic at McMurdo Station was not observed, but interference was a problem in work with unshielded antennas near buildings. In general, the results of this field test suggest that high-quality, high-resolution, continuous subsurface profiles can be producedmore » with GPR over most of McMurdo Station.« less

Application of ground-penetrating radar at McMurdo Station, Antarctica

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

Stefano, J.E.

1992-01-01

Argonne National Laboratory initiated a site investigation program at McMurdo Station, Antarctica, to characterize environmental contamination. The performance and usefulness of ground-penetrating radar (GPR) was evaluated under antarctic conditions during the initial site investigation in January 1991. Preliminary surveys were successful in defining the contact between reworked pyroclastic material and in the prefill, undisturbed pyroclastics and basalts at some sites. Interference from radio traffic at McMurdo Station was not observed, but interference was a problem in work with unshielded antennas near buildings. In general, the results of this field test suggest that high-quality, high-resolution, continuous subsurface profiles can be producedmore » with GPR over most of McMurdo Station.« less

Distribution of Root-Associated Bacterial Communities Along a Salt-Marsh Primary Succession.

PubMed

Wang, Miao; Yang, Pu; Falcão Salles, Joana

2015-01-01

Proper quantification of the relative influence of soil and plant host on the root-associated microbiome can only be achieved by studying its distribution along an environmental gradient. Here, we used an undisturbed salt marsh chronosequence to study the bacterial communities associated with the soil, rhizosphere and the root endopshere of Limonium vulgare using 454-pyrosequencing. We hypothesize that the selective force exerted by plants rather than soil would regulate the dynamics of the root-associated bacterial assembly along the chronosequence. Our results showed that the soil and rhizosphere bacterial communities were phylogenetically more diverse than those in the endosphere. Moreover, the diversity of the rhizosphere microbiome followed the increased complexity of the abiotic and biotic factors during succession while remaining constant in the other microbiomes. Multivariate analyses showed that the rhizosphere and soil-associated communities clustered by successional stages, whereas the endosphere communities were dispersed. Interestingly, the endosphere microbiome showed higher turnover, while the bulk and rhizosphere soil microbiomes became more similar at the end of the succession. Overall, we showed that soil characteristics exerted an overriding influence on the rhizosphere microbiome, although plant effect led to a clear diversity pattern along the succession. Conversely, the endosphere microbiome was barely affected by any of the environmental measurements and very distinct from other communities.

Paleomagnetism and Magnetostratigraphy of Upper Permian to Lower Triassic (?) Beaufort Group Strata at Bethulie, Karoo Basin, Free State Province, South Africa

NASA Astrophysics Data System (ADS)

Geissman, J. W.; Gastaldo, R. A.; Neveling, J.; Makubalo, S.

2017-12-01

A multifaceted approach to understand the timing of interpreted environmental changes during the Late Permian to possibly Early Triassic (?) time in the Beaufort Group strata of the Karoo Basin includes work to establish robust magnetic polarity records for sections previously interpreted to encompass end-Permian extinction events. Demonstrating the preservation of an early-acquired remanence (RM) in Karoo strata is required for a robust magnetostratigraphy. Yet, this is challenging due to thermochemical effects related to the Early Jurassic (ca. 183 Ma) Karoo Large Igneous Province (LIP), and the NE to SW increase in burial diagenesis attending Cape Fold Belt tectonism. Documentation of a primary RM in these strata, which appears to be preserved in some areas, requires careful laboratory- and field-based assessment. We report data from 53 sites collected at the well-studied Bethulie section, Free State Province, in which several <2 m wide Karoo LIP dikes crop out. We obtained 7-10+ independent samples per individual horizon to assess ChRM uniformity. Strata well-removed from dikes yield both normal and reverse polarity ChRM. It is always the case that the first-removed RM is a NNW seeking, moderate to steep negative-inclination ChRM (normal polarity); NRM intensities are typically 1 to 5 mA/m. Sites BT15 and BT21, which are located in strata lying some 4 m below the often-cited "event bed" interval inferred to be the terrestrial expression of the Permian/Triassic boundary, is dominated by a well-defined reverse RM with a normal overprint RM unblocked below 400oC, implying elevated temperatures (i.e., 100 to 250oC+) for ca. 1 Ma (+/-). Contact tests are positive but complicated. Host strata collected in distances equal to or less than 1-2 dike widths from the intrusions have been thermally remagnetized and demonstrate high NRM intensities (> 50 mA/m). Collectively, we interpret these data to indicate that any ChRM, with the exception of those from host strata in baked contacts, that persists above Tlub of 425oC is pre-Karoo LIP in origin, and likely primary at the Bethulie locality.

Infrared measurements of pristine and disturbed soils 1. Spectral contrast differences between field and laboratory data

USGS Publications Warehouse

Johnson, J. R.; Lucey, P.G.; Horton, K.A.; Winter, E.M.

1998-01-01

Comparison of emissivity spectra (8-13 ??m) of pristine soils in the field with laboratory reflectance spectra of the same soils showed that laboratory spectra tend to have less spectral contrast than field spectra (see following article). We investigated this the phenomenon by measuring emission spectra of both undisturbed (in situ) and disturbed soils (prepared as if for transport to the laboratory). The disturbed soils had much less spectral contrast than the undisturbed soils in the reststrahlen region near 9 ??m. While the increased porosity of a disturbed soil can decrease spectral contrast due to multiple scattering, we hypothesize that the effect is dominantly the result of a difference in grain-size distribution of the optically active layer (i.e., fine particle coatings). This concept was proposed by Salisbury et al. (1994) to explain their observations that soils washed free of small particles adhering the larger grains exhibited greater spectral contrast than unwashed soils. Our laboratory reflectance spectra of wet- and dry-sieved soils returned from field sites also show greater spectral contrast for wet-sieved (washed) soils. We therefore propose that undisturbed soils in the field can be characterized as 'clean' soils (washed free of fine particles at the surface due to rain and wind action) and that disturbed soils represent 'dirty' soils (contaminated with fine particle coatings). The effect of packing soils in the field and laboratory also increases spectral contrast but not to the magnitude of that observed for undisturbed and wet-sieved soils. Since it is a common practice to use laboratory spectra of field samples to interpret spectra obtained remotely, we suggest that the influence of fine particle coatings on disturbed soils, if unrecognized, could influence interpretations of remote sensing data.Comparison of emissivity spectra (8-13 ??m) of pristine soils in the field with laboratory reflectance spectra of the same soils showed that laboratory spectra tend to have less spectral contrast than field spectra (see following article). We investigated this phenomenon by measuring emission spectra of both undisturbed (in situ) and disturbed soils (prepared as if for transport to the laboratory). The disturbed soils had much less spectral contrast than the undisturbed soils in the reststrahlen region near 9 ??m. While the increased porosity of a disturbed soil can decrease spectral contrast due to multiple scattering, we hypothesize that the effect is dominantly the result of a difference in grain-size distribution of the optically active layer (i.e., fine particle coatings). This concept was proposed by Salisbury et al. (1994) to explain their observations that soils washed free of small particles adhering to larger grains exhibited greater spectral contrast than unwashed soils. Our laboratory reflectance spectra of wet- and dry-sieved soils returned from field sites also show greater spectral contrast for wet-sieved (washed) soils. We therefore propose that undisturbed soils in the field can be characterized as `clean' soils (washed free of fine particles at the surface due to rain and wind action) and that disturbed soils represent `dirty' soils (contaminated with fine particle coatings). The effect of packing soils in the field and laboratory also increases spectral contrast but not to the magnitude of that observed for undisturbed and wet-sieved soils. Since it is a common practice to use laboratory spectra of field samples to interpret spectra obtained remotely, we suggest that the influence of fine particle coatings on disturbed soils, if unrecognized, could influence interpretations of remote sensing data.

Paleomagnetic poles and polarity zonation from the middle proterozoic belt supergroup, montana and Idaho

NASA Astrophysics Data System (ADS)

Elston, Donald P.; Bressler, Stephen L.

1980-01-01

Twelve paleomagnetic poles and a preliminary polarity zonation are reported from geologically mapped, stratigraphically controlled sections of the middle Proterozoic Belt Supergroup in western Montana and northern Idaho. Although gaps exist in the stratigraphic coverage, the lower Belt, Ravalli Group, and middle Belt carbonate appear to be largely if not entirely of normal polarity. A switch to reversed polarity takes place near the base of the overlying Missoula Group (base of Snowslip Fomration), and two comparatively narrow intervals of mixed polarity containing at least 18 reversals are found in the lower and middle Snowslip. Seven reversals, mostly widely spaced in stratigraphic position, have been found in overlying strata of the Missoula Group. Poles from strata of the Ravalli Group through Missoula Group are well defined and tightly clustered. They plot in the south-central Pacific Ocean and display only a small (~20°) southeast to northwest shift in pole path. Poles from Belt strata in the eastern basin plot sytematically east of poles from the more westerly collection sites. A counterclockwise shift in declination of 7°-10° is seen in strata from the easterly sites, which has given rise to a curving pole path that closely parallels the path for the westerly sites. This easterly path appears explainable as a consequence of a counterclokwise structural rotation of eastern Belt strata relative to western and central Belt strata produced during west ot east thrust faulting of late Mesozoic and early Cenozoic age. An additional counterclockwise rotation of the same magnitude exists between the northern and southern parts of the Montana fisturbed belt of the eastern Belt basin. Moreover, anomalously steep inclinations, not yet explained, have been reported from some of the strata sampled at the north end of the disturbed belt. The steep inclinations result in poles that plot distinctly east of poles reported from this study. The Belt pole path lies in a part of the North American apparent polar wander path that has been assigned an age of about 1500-1200 m.y. This is in broad agreement with isotopic ages reported for strata of the lower Belt to the middle Ravalli Group. The Belt path trends toward, and its northwest end overlaps, the beginning of the pole path for the Grand Canyon Supergroup, which formed in the interval from <~1300 to ~830 m.y. ago. Because polarity zonations differ between strata of the upper Belt and lower Grand Canyon Supergroups. Belt strata would appear, on paleomagnetic grounds, to be largely or entirely older than strata of the Grand Canyon Supergroup. However, isotopic ages for the Missoula Group (1100 m.y. and younger) presently require an alternative interpretation, i.e., that the Belt terrance did not participate in inferred plate motion which gave rise to a large north-trending loop in the inverval ~1200 to ~1100 m.y. ago and to later motion seen in the Grand Canyon path. Additional dating is needed for the Purcell Lava of the Missoula Group to support or modify the 1100 m.y. age determined by the K-Ar method.

Publications - GMC 69 | Alaska Division of Geological & Geophysical Surveys

Science.gov Websites

DGGS GMC 69 Publication Details Title: Magnetic properties of greigite-bearing Cretaceous strata, North , 1987, Magnetic properties of greigite-bearing Cretaceous strata, North Slope, Alaska (abstract only

Modulation of contextual fear conditioning by chronic stress in rats is related to individual differences in behavioral reactivity to novelty.

PubMed

Cordero, M Isabel; Kruyt, Nyika D; Sandi, Carmen

2003-04-25

We investigated whether contextual fear conditioning could be related to the behavioral trait of locomotor reactivity to novelty in undisturbed and chronically stressed rats. Fear conditioning was found to be specifically enhanced in low reactive-stressed animals, as compared to low reactive-undisturbed rats. The results suggest that individuals that display low reactivity to novelty are more susceptible to be influenced by stress exposure to subsequently exhibit potentiated contextual fear conditioning.

Malignant melanoma in Chile: different site distribution between private and state patients.

PubMed

Zemelman, Viviana B; Valenzuela, Carlos Y; Sazunic, Ivo; Araya, Irene

2014-01-01

The body site location of primary Malignant Melanoma (MM) has been correlated with prognosis and survival. Ethnic, genetics, sun exposure factors are related to the anatomical distribution of MM. Low and high socioeconomic strata in Chile differ in ethnic, genetic and cultural conditions. The purpose of this study was to analyze the anatomical MM distribution in the Chilean population in both strata searching for differences due to their ethno-genetic-cultural differences. Records of 1148 MM, 575 cases from state hospitals (Low Socioeconomic Strata, LSS) and 573 cases from private clinics (High Socioeconomic Strata, HSS) were analyzed by body site. Females from LSS showed a higher number of MM in soles, cheeks, and around the eye area. Females from the HSS showed a higher number of MM in dorsal feet and dorsal hands. Males from LSS showed a higher number of MM in soles, around the eye area, and cheeks. However, males from HSS showed a higher number of MM in the trunk, and in the arms. Acral MM was significantly higher in LSS than in the HSS in both sexes. The Chilean population from the HSS and LSS showed differences in the distribution of MM by site. Furthermore, gender differences in the proportion of MM analyzed by anatomical site are observed in both strata. Results show evidence that differential genetics factors, sun exposure, or other environmental or cultural factors of both strata may account for these differences.

Resources or landmarks: which factors drive homing success in Tetragonula carbonaria foraging in natural and disturbed landscapes?

PubMed

Leonhardt, Sara D; Kaluza, Benjamin F; Wallace, Helen; Heard, Tim A

2016-10-01

To date, no study has investigated how landscape structural (visual) alterations affect navigation and thus homing success in stingless bees. We addressed this question in the Australian stingless bee Tetragonula carbonaria by performing marking, release and re-capture experiments in landscapes differing in habitat homogeneity (i.e., the proportion of elongated ground features typically considered prominent visual landmarks). We investigated how landscape affected the proportion of bees and nectar foragers returning to their hives as well as the earliest time bees and foragers returned. Undisturbed landscapes with few landmarks (that are conspicuous to the human eye) and large proportions of vegetation cover (natural forests) were classified visually/structurally homogeneous, and disturbed landscapes with many landmarks and fragmented or no extensive vegetation cover (gardens and plantations) visually/structurally heterogeneous. We found that proportions of successfully returning nectar foragers and earliest times first bees and foragers returned did not differ between landscapes. However, most bees returned in the visually/structurally most (forest) and least (garden) homogeneous landscape, suggesting that they use other than elongated ground features for navigation and that return speed is primarily driven by resource availability in a landscape.

Diarrhea no more: does zinc help the poor? Evidence on the effectiveness of programmatic efforts to reach poorest in delivering zinc and ORS at scale in UP and Gujarat, India.

PubMed

LeFevre, Amnesty E; Mohan, Diwakar; Mazumder, Sarmila; Lamberti, Laura L; Taneja, Sunita; Black, Robert E; Fischer-Walker, Christa L

2016-12-01

India has the greatest burden of diarrhea in children under 5 years globally. The Diarrhea Alleviation through zinc and oral rehydration salts (ORS) Therapy program (2010-2014) sought to improve access to and utilization of zinc and ORS among children 2-59 months in Gujarat and Uttar Pradesh (UP), India, through public and private sector delivery channels. In this analysis, we present findings on program's effect in reducing child-health inequities. Data from cross-sectional baseline and endline surveys were used to assess disparities in key outcomes across six dimensions: socioeconomic strata, gender, caregiver education, ethnicity and geography. Careseeking outside the home for children under 5 years with diarrhea did not increase significantly in UP or Gujarat across socioeconomic strata. Declines in private sector careseeking were observed in both sites along with concurrent increases in public sector careseeking. Zinc, ORS, zinc+ORS use did not increase significantly in UP across socioeconomic strata. In Gujarat, increases in zinc use (20% overall; 33% in the Quintile 5 (Q5) strata) and zinc+ORS (18% overall; 30% in the Q5 strata) were disproportionately observed in the high income strata, among members of the most advantaged caste, and among children whose mothers had ≥1 year of schooling. ORS use increased significantly across all socioeconomic strata for children in Gujarat with diarrhea (23% overall; 33% in Q5 strata) and those with dehydration + diarrhea (33% overall; 38% in Q5 strata). The magnitude of increase in ORS receipt from the public sector was nearly twice that observed in the private sector. In Gujarat, while out of pocket spending for diarrhea was significantly higher for male children, overall costs to users declined by a mean of US$ 2; largely due to significant reductions in wages lost (-US$ 0.79; P  < 0.003), and transportation costs (-US$ 0.44; P  < 0.00). While significant improvements in diarrhea treatment were achieved in Gujarat, new strategies are needed in UP, particularly in the private sector. If national-level reductions in diarrheal disease burden are to be realized, improved understanding is needed of how to optimally increase coverage of zinc and ORS and decrease contraindicated treatments amongst the most disadvantaged across geographic areas and axes of gender, ethnicity, education and socioeconomic status.

Runoff and soil erosion for an undisturbed tropical woodland in the Brazilian Cerrado

NASA Astrophysics Data System (ADS)

Oliveira, Paulo Tarso S.; Nearing, Mark; Wendland, Edson

2015-04-01

The Brazilian Cerrado is a large and important economic and environmental region that is experiencing major loss of its natural landscapes due to pressures of food and energy production, which has caused large increases in soil erosion. However the magnitude of the soil erosion increases in this region is not well understood, in part because scientific studies of surface runoff and soil erosion are scarce or nonexistent in undisturbed Cerrado vegetation. In this study we measured natural rainfall-driven rates of runoff and soil erosion for an undisturbed tropical woodland classified as "cerrado sensu stricto denso" and bare soil to compute the Universal Soil Loss Equation (USLE) cover and management factor (C-factor) to help evaluate the likely effects of land use change on soil erosion rates. Replicated data on precipitation, runoff, and soil loss on plots (5 x 20 m) under bare soil and cerrado were collected for 55 erosive storms occurring in 2012 and 2013. The measured annual precipitation was 1247.4 mm and 1113.0 mm for 2012 and 2013, resulting in a rainfall erosivity index of 4337.1 MJ mm ha-1 h-1 and 3546.2 MJ mm ha-1 h-1, for each year respectively. The erosive rainfall represented 80concentrated in the wet season, which generally runs from October through March. In the plots on bare soil, the runoff coefficient for individual rainfall events (total runoff divided by total rainfall) ranged from 0.003 to 0.860 with an average value and standard deviation of 0.212 ± 0.187. Moreover, the runoff coefficient found for the bare soil plots (~20infiltration capacity. In forest areas the leaf litter and the more porous soil tend to promote the increase of infiltration and water storage, rather than rapid overland flow. Indeed, runoff coefficients ranged from 0.001 to 0.030 with an average of less than 1under undisturbed cerrado. The soil losses measured under bare soil and cerrado were 15.68 t ha-1yr-1 and 0.24 t ha-1 yr-1 in 2012, and 14.82 t ha-1 yr-1, 0.11 t ha-1 yr-1 in 2013, respectively, with means of total soil loss during the study period of 15.25 t ha-1 yr-1 and 0.17 t ha-1 yr-1. The erosivity-weighted C-factor for the undisturbed cerrado vegetation was 0.013. Previous studies have shown that, in general, the C-factors for Brazilian crops cover an approximate 10-fold range, from 2 to 39-times greater than the C-factor for undisturbed cerrado. Our results suggest that though soil erosion under undisturbed Cerrado is important, shifts in land use from the native to cultivated vegetation may result in orders of magnitude increases in soil loss rates. These results provide benchmark values that will be useful to evaluate past and future land use changes using soil erosion models and measurements.

Dynamics of bacterial community succession in a salt marsh chronosequence: evidences for temporal niche partitioning.

PubMed

Dini-Andreote, Francisco; de Cássia Pereira e Silva, Michele; Triadó-Margarit, Xavier; Casamayor, Emilio O; van Elsas, Jan Dirk; Salles, Joana Falcão

2014-10-01

The mechanisms underlying community assembly and promoting temporal succession are often overlooked in microbial ecology. Here, we studied an undisturbed salt marsh chronosequence, spanning over a century of ecosystem development, to understand bacterial succession in soil. We used 16S rRNA gene-based quantitative PCR to determine bacterial abundance and multitag 454 pyrosequencing for community composition and diversity analyses. Despite 10-fold lower 16S rRNA gene abundances, the initial stages of soil development held higher phylogenetic diversities than the soil at late succession. Temporal variations in phylogenetic β-diversity were greater at initial stages of soil development, possibly as a result of the great dynamism imposed by the daily influence of the tide, promoting high immigration rates. Allogenic succession of bacterial communities was mostly driven by shifts in the soil physical structure, as well as variations in pH and salinity, which collectively explained 84.5% of the variation concerning community assemblage. The community assembly data for each successional stage were integrated into a network co-occurrence analysis, revealing higher complexity at initial stages, coinciding with great dynamism in turnover and environmental variability. Contrary to a spatial niche-based perspective of bacterial community assembly, we suggest temporal niche partitioning as the dominant mechanism of assembly (promoting more phylotype co-occurrence) in the initial stages of succession, where continuous environmental change results in the existence of multiple niches over short periods of time.

Dynamics of bacterial community succession in a salt marsh chronosequence: evidences for temporal niche partitioning

PubMed Central

Dini-Andreote, Francisco; de Cássia Pereira e Silva, Michele; Triadó-Margarit, Xavier; Casamayor, Emilio O; van Elsas, Jan Dirk; Salles, Joana Falcão

2014-01-01

The mechanisms underlying community assembly and promoting temporal succession are often overlooked in microbial ecology. Here, we studied an undisturbed salt marsh chronosequence, spanning over a century of ecosystem development, to understand bacterial succession in soil. We used 16S rRNA gene-based quantitative PCR to determine bacterial abundance and multitag 454 pyrosequencing for community composition and diversity analyses. Despite 10-fold lower 16S rRNA gene abundances, the initial stages of soil development held higher phylogenetic diversities than the soil at late succession. Temporal variations in phylogenetic β-diversity were greater at initial stages of soil development, possibly as a result of the great dynamism imposed by the daily influence of the tide, promoting high immigration rates. Allogenic succession of bacterial communities was mostly driven by shifts in the soil physical structure, as well as variations in pH and salinity, which collectively explained 84.5% of the variation concerning community assemblage. The community assembly data for each successional stage were integrated into a network co-occurrence analysis, revealing higher complexity at initial stages, coinciding with great dynamism in turnover and environmental variability. Contrary to a spatial niche-based perspective of bacterial community assembly, we suggest temporal niche partitioning as the dominant mechanism of assembly (promoting more phylotype co-occurrence) in the initial stages of succession, where continuous environmental change results in the existence of multiple niches over short periods of time. PMID:24739625

Salt fluoridation and oral health.

PubMed

Marthaler, Thomas M

2013-11-01

The aim of this paper is to make known the potential of fluoridated salt in community oral health programs, particularly in South Eastern Europe. Since 1922, the addition of iodine to salt has been successful in Switzerland. Goiter is virtually extinct. By 1945, the caries-protective effect of fluorides was well established. Based on the success of water fluoridation, a gynecologist started adding of fluoride to salt. The sale of fluoridated salt began in 1956 in the Swiss Canton of Zurich, and several other cantons followed suit. Studies initiated in the early seventies showed that fluoride, when added to salt, inhibits dental caries. The addition of fluoride to salt for human consumption was officially authorized in 1980-82. In Switzerland 85% of domestic salt consumed is fluoridated and 67% in Germany. Salt fluoridation schemes are reaching more than one hundred million in Mexico, Colombia, Peru and Cuba. The cost of salt fluoridation is very low, within 0.02 and 0.05 € per year and capita. Children and adults of the low socio-economic strata tend to have substantially more untreated caries than higher strata. Salt fluoridation is by far the cheapest method for improving oral health. Salt fluoridation has cariostatic potential like water fluoridation (caries reductions up to 50%). In Europe, meaningful percentages of users have been attained only in Germany (67%) and Switzerland (85%). In Latin America, there are more than 100 million users, and several countries have arrived at coverage of 90 to 99%. Salt fluoridation is by far the cheapest method of caries prevention, and billions of people throughout the world could benefit from this method. Copyright © 2013 by Academy of Sciences and Arts of Bosnia and Herzegovina.

Directionality of Spectral and Polarimetric Measurements of Soils

NASA Astrophysics Data System (ADS)

Furey, J.; Zahniser, S. R.; Morgan, C.; Lewis, M. G.

2017-12-01

Spectral and polarimetric instruments mounted on a goniometer in a laboratory setting measured directionality effects for discriminating disturbed from undisturbed soils at varied illumination and look angles. Over 8000 custom polarimetric images, using rotating linear polarizers, were acquired at 63 goniometer positions in the Visible (Vis), Near InfraRed (NIR), Short Wave IR (SWIR), and Long Wave IR (LWIR) spectral bands, as well as a hyperspectral imager in the Vis through NIR (Resonon Pika), and a nonimaging hyperspectral instrument (ASD Fieldspec). The soils had been sampled from earlier field studies in the Global Undisturbed/Disturbed Earth (GUIDE) program, and the soil surfaces were prepared in disturbed and undisturbed states for laboratory measurement. No one spectral range was most effective at discriminating at all azimuth and elevation angles for any soil, but polarimetric SWIR was the most often effective. Azimuthal spectral variations did not provide statistically significant discrimination in themselves. Other preliminary findings are that polarimetry is key to understanding azimuthal effects and that nadir spectra are the least predictive.

Effects of bottom fishing on the benthic megafauna of Georges Bank

USGS Publications Warehouse

Collie, J.S.; Escanero, G.A.; Valentine, P.C.

1997-01-01

This study addresses ongoing concerns ever the effects of mobile fishing gear on benthic communities. Using side-scan sonar, bottom photographs and fishing records, we identified a set of disturbed and undisturbed sites on the gravel pavement area of northern Georges Bank in the northwest Atlantic. Replicate samples of the megofauna were collected with a 1 m Naturalists' dredge on 2 cruises in 1994. Compared with the disturbed sites, the undisturbed sites had higher numbers of organisms, biomass, species richness and species diversity; evenness was higher at the disturbed sites. Undisturbed sites were characterized by an abundance of bushy epifaunal taxa (bryozoans, hydroids, worm tubes) that provide a complex habitat for shrimps, polychaetes, brittle stars, mussels and small fish. Disturbed sites were dominated by larger, hard-shelled molluscs, and scavenging crabs and echinoderms. Many of the megafaunal species in our samples have also been identified in stomach contents of demersal fish on Georges Bank; the abundances of at feast some of these species were reduced at the disturbed sites.

Fipronil mobility and transformation in undisturbed soil columns.

PubMed

Chatterjee, Niladri Sekhar; Gupta, Suman

2010-08-01

The downward movement of fipronil and its two toxic metabolites i.e. sulfone and desulfinyl were studied in undisturbed soil columns. Mobility behavior of two different formulations of fipronil viz granular and suspension concentrate were also studied. The undisturbed columns containing sandy loam soil were leached with water equivalent to 400 mm rainfall. Results revealed that although majority of the fipronil (approximately 80%) remained in top 0-5 cm layer, substantial amount (approximately 15%) moved to 5-10 cm depth. In case of metabolites sulfone and desulfinyl >90% of the residues remained in 0-5 cm core indicating low mobility of these metabolites in comparison to fipronil. Results of mobility behavior of fipronil in granular and SC formulations revealed low mobility in granular formulation. Sulfide was detected as the major degradation product in both the formulations and was found to be distributed throughout the column. A little amount of sulfone (0.1% of the total recovered) was also detected upto 10 cm depth.

Early to middle Jurassic salt in Baltimore Canyon trough

USGS Publications Warehouse

McKinney, B. Ann; Lee, Myung W.; Agena, Warren F.; Poag, C. Wylie

2005-01-01

A pervasive, moderately deep (5-6 s two-way traveltime), high-amplitude reflection is traced on multichannel seismic sections over an approximately 7500 km² area of Baltimore Canyon Trough. The layer associated with the reflection is about 25 km wide, about 60 m thick in the center, and thins monotonically laterally, though asymmetrically, at the edges. Geophysical characteristics are compatible with an interpretation of this negative-polarity reflector as a salt lens deposited on the top of a synrift evaporite sequence. However, alternative interpretations of the layer as gas-saturated sediments, an overpressured shale, or a weathered igneous intrusion are also worthy of consideration.Geophysical analyses were made on three wavelet- and true-amplitude processed multichannel seismic dip lines. The lens-shaped layer demarked by the reflection has a velocity of 4.4 km/s; the lens lies within strata having velocities of 5.3 to 5.7 km/s. A trough marking the onset of the lens has an amplitude that is 10 to 20 db greater than reflections from the encasing layers and an apparent reflection coefficient of -0.24. Using amplitude versus offset analysis methods, we determined that observed reflection coefficients, though variable, decrease consistently with respect to increasing offset. Linear inversion yields a low density, about 2.2 g/cc. Integration of one of the true-amplitude-processed lines and one-dimensional modeling of the layer provide data on the impedance contrast and interference patterns that further reinforce the salt lens interpretation.The thin, horizontal salt lens was probably deposited or precipitated during the Jurassic in a shallow, narrow (peripheral) rift basin, as rifting progressed down the North Atlantic margin. Unlike thicker deposits in other areas that deformed and flowed, often into diapir structures, this thin lens has remained relatively undisturbed since deposition.

Variation in glycogen concentrations within mantle and foot tissue in Amblema plicata plicata: Implications for tissue biopsy sampling

USGS Publications Warehouse

Naimo, T.J.; Monroe, E.M.

1999-01-01

With the development of techniques to non-lethally biopsy tissue from unionids, a new method is available to measure changes in biochemical, contaminant, and genetic constituents in this imperiled faunal group. However, before its widespread application, information on the variability of biochemical components within and among tissues needs to be evaluated. We measured glycogen concentrations in foot and mantle tissue in Amblema plicata plicata (Say, 1817) to determine if glycogen was evenly distributed within and between tissues and to determine which tissue might be more responsive to the stress associated with relocating mussels. Glycogen was measured in two groups of mussels: those sampled from their native environment (undisturbed mussels) and quickly frozen for analysis and those relocated into an artificial pond (relocated mussels) for 24 months before analysis. In both undisturbed and relocated mussels, glycogen concentrations were evenly distributed within foot, but not within mantle tissue. In mantle tissue, concentrations of glycogen varied about 2-fold among sections. In addition, glycogen varied significantly between tissues in undisturbed mussels, but not in relocated mussels. Twenty-four months after relocation, glycogen concentrations had declined by 80% in mantle tissue and by 56% in foot tissue relative to the undisturbed mussels. These data indicate that representative biopsy samples can be obtained from foot tissue, but not mantle tissue. We hypothesize that mantle tissue could be more responsive to the stress of relocation due to its high metabolic activity associated with shell formation.

Lower Cretaceous bentonitic strata in southwestern Montana assigned to Vaughn Member of Mowry Shale (East) and of Blackleaf Formation (West)

USGS Publications Warehouse

Tysdal, R.G.; Dyman, T.S.; Nichols, D.J.

1989-01-01

The Vaughn Member, newly assigned to the Mowry Shale in this report, comprises strata that crop out in the Greenhorn, Gravelly, Madison, and Gallatin ranges, and the Centennial and Beartooth mountains of southwestern Montana. Herein the member is correlated with the Vaughn Member of the Blackleaf Formation, which crops out to the west in the Lima Peaks area, Snowcrest Range, and Pioneer Mountains. Strata assigned to the Vaughn Member of the Blackleaf Formation in southwestern Montana exhibit the same contrasting relationships that exist in northwestern Montana. The Vaughn Member of the Mowry is late Albian in age, determined by bracketing with shallow water marine bivalves in the Muddy Sandstone below and palynomorphs in Mowry strata above. Palynomorphs from the Vaughn Member itself are typically mid-Cretaceous, but do not permit a more exact determination of age. -from Authors

Improving participant selection in disease management programmes: insights gained from propensity score stratification.

PubMed

Linden, Ariel; Adams, John L

2008-10-01

While the randomized controlled trial (RCT) remains the gold-standard study design for evaluating treatment effect, outcomes researchers turn to powerful quasi-experimental designs when only observational studies can be conducted. Within these designs, propensity score matching is one of the most popular to evaluate disease management (DM) programme effectiveness. Given that DM programmes generally have a much smaller number of participants than non-participants in the population, propensity score matching will typically result in all or nearly all participants finding successful matches, while most of the non-participants in the population remain unmatched and thereby excluded from the analysis. By excluding data from the unmatched population, the effect of non-treatment in the remaining population with the disease is not captured. In the present study, we examine changes in hospitalization rates stratified by propensity score quintiles across the entire population allowing us to gain insight as to how well the programme chose its participants, or if the programme could have been effective on those individuals not explicitly targeted for the intervention. These data indicate the presence of regression to the mean, and suggest that the DM programme may be overly limited to only the highest strata when there is evidence of a potential benefit for those in all the lower strata as well.

Combined intracranial pressure monitoring and cerebrospinal fluid infusion study to guide management of slit ventricle syndrome.

PubMed

Hart, Michael Gavin; Czosnyka, Marek; Czosnyka, Zofia Helena; Fernandes, Helen Marie

2013-01-01

Slit ventricle syndrome remains a complex entity presenting a considerable challenge to treat successfully. This study aims to demonstrate the application of dual intracranial pressure (ICP) and infusion studies together with the novel shunt occlusion test in both a diagnostic and therapeutic role. An 8-year-old child had aqueduct stenosis treated with a ventriculoperitoneal shunt (medium-pressure valve). The presentation was of headaches with papilloedema. Imaging with both computed tomography and magnetic resonance imaging revealed slit ventricles. Initially a shunt exploration revealed distal obstruction that was treated together with insertion of a paediatric strata II regular valve; however, the child continued to deteriorate. Overnight ICP monitoring revealed dramatically raised ICP with poor compensatory reserve. Intra-operative infusion study revealed a shunt that was patent distally but with proximal obstruction. A subtemporal decompression ipsilateral to the shunt was performed together with adjustment of the paediatric strata II regular valve to 2.5 in order to prevent overdrainage. This led to normalisation of ICP, resolution of papilloedema and symptomatic improvement. We demonstrate how combined ICP monitoring and shunt infusion studies can be used to help guide management. Unilateral subtemporal decompressions and preventing shunt overdrainage can result in normalisation of ICP and cerebrospinal fluid dynamics.

Recognizing the Albian-Cenomanian (OAE1d) sequence boundary using plant carbon isotopes: Dakota Formation, Western Interior Basin, USA

USGS Publications Warehouse

Grocke, D.R.; Ludvigson, Greg A.; Witzke, B.L.; Robinson, S.A.; Joeckel, R.M.; Ufnar, David F.; Ravn, R.L.

2006-01-01

Analysis of bulk sedimentary organic matter and charcoal from an Albian-Cenomanian fluvial-estuarine succession (Dakota Formation) at Rose Creek Pit (RCP), Nebraska, reveals a negative excursion of ???3???, in late Albian strata. Overlying Cenomanian strata have ??13C values of -24???, to -23???, that are similar to pre-excursion values. The absence of an intervening positive excursion (as exists in marine records of the Albian-Cenomanian boundary) likely results from a depositional hiatus. The corresponding positive ??13C event and proposed depositional hiatus are concordant with a regionally identified sequence boundary in the Dakota Formation (D2), as well as a major regressive phase throughout the globe at the Albian-Cenomanian boundary. Data from RCP confirm suggestions that some positive carbon-isotope excursions in the geologic record are coincident with regressive sea-level phases. We estimate using isotopic correlation that the D2 sequence boundary at RCP was on the order of 0.5 m.y. in duration. Therefore, interpretations of isotopic events and associated environmental phenomena, such as oceanic anoxic events, in the shallow-marine and terrestrial record may be influenced by stratigraphic incompleteness. Further investigation of terrestrial ??13C records may be useful in recognizing and constraining sea-level changes in the geologic record. ?? 2006 Geological Society of America.

Linking sediment structure, hydrological functioning and biogeochemical cycling in disturbed coastal saltmarshes and implications for vegetation development

NASA Astrophysics Data System (ADS)

Spencer, Kate; Harvey, Gemma; James, Tempest; Simon, Carr; Michelle, Morris

2014-05-01

Saltmarsh restoration undoubtedly provides environmental enhancement, with vegetation quickly re-establishing following the breach of sea walls and subsequent tidal inundation of previously defended areas. Yet evidence increasingly suggests that the restored saltmarshes do not have the same biological characteristics as their natural counterparts (Mossman et al. 2012) and this may be in part be due to physicochemical parameters at the site including anoxia and poor drainage. Hence, restored saltmarshes may not offer the range and quality of ecosystem services anticipated. These environments will have been 'disturbed' by previous land use and there is little understanding of the impacts of this disturbance on the wider hydrogeomorphic and biogeochemical functioning in restored saltmarshes and the implications for saltmarsh vegetation development. This study examines linkages between physical sediment characteristics, sediment structure (using X-ray microtomography), sub-surface hydrology (using pressure transducers and time series analysis), and sediment and porewater geochemistry (major and trace elements, major anions) in sediment cores collected from undisturbed saltmarshes and those restored by de-embankment. Sub-surface sediments in restored saltmarshes have lower organic matter content, lower moisture content and higher bulk density than undisturbed sites. Using X-ray tomography a clear horizon can be observed which separates relict agricultural soils at depth with less dense and structureless sediments deposited since de-embankment. Ratios of open to closed pore space suggest that while undisturbed saltmarshes have the highest porosity, restored saltmarshes have larger void spaces, but limited pore connectivity. Sub-surface hydrological response to tidal flooding was subdued in the restored compared to the undisturbed site, suggesting that porewater flow may be impeded. Time series analysis indicated that flow pathways differ in restored saltmarsh sediments with preferential horizontal flows. The undisturbed saltmarsh displayed typical vertical geochemical sediment profiles. However, in the restored sites total Fe and Mn are elevated at depth indicating an absence of diagenetic cycling, whilst porewater sulphate and nitrate increased at depth suggesting that vertical solute transport is impeded in restored sites. In surface sediments, though total Hg concentrations are similar, Hg methylation rates are significantly higher than in the undisturbed saltmarsh suggesting that surface anoxia and poor drainage may result in increased mobilization and bioavailability of Hg. These findings have implications for the wider biogeochemical ecosystem services offered by saltmarsh restoration and the water-logged, anoxic conditions produced are unsuitable for seedling germination and plant growth. This highlights the need for integrated understanding of physical and biogeochemical processes.

A Jurassic Shock-Aftershock Earthquake Sequence Recorded by Small Clastic Pipes and Dikes within Dune Cross-Strata, Zion National Park, Utah

NASA Astrophysics Data System (ADS)

Loope, D. B.; Zlotnik, V. A.; Kettler, R. M.; Pederson, D. T.

2012-12-01

Eolian sandstones of south-central and southeast Utah contain large volumes of contorted cross-strata that have long been recognized as products of liquefaction caused by seismic shaking. Unlike most sites where Navajo Sandstone is exposed, in Zion National Park (southwestern Utah), the Navajo contains very, very few contorted strata. We have, however, mapped the distribution of more than 1,000 small-scale, vertical pipes and dikes in uncontorted cross-strata of the Navajo at two small study sites in Zion. Pipes are 2-5 cm in diameter and up to 3 m long; dikes are ~6 cm wide. Clusters of the water-escape structures lie directly above and below numerous, near-horizontal bounding surfaces. Dikes are restricted to the wind-ripple strata that lie above the bounding surfaces. Pipes are common both above and below the bounding surfaces. In map view, most pipes are arranged in lines. Near the bounding surfaces, pipes merge upward with shallow dikes trending parallel to the lines of pipes. Pipes formed in grainflows—homogeneous, well-sorted sand lacking cohesion. Dikes formed above the bounding surface, in more-cohesive, poorly sorted, wind-ripple strata. As liquefaction began, expansion of subsurface sand caused spreading within the unliquified (capping) beds near the land surface. Dikes intruded cracks in the wind-ripple strata, and pipes rose from the better-sorted sand to interdune surfaces, following trends of cracks. Because the wind-ripple strata had low cohesive strength, a depression formed around each rupture, and ejected sand built upward to a flat-topped surface rather than forming the cone of a classic sand volcano. In one 3 m2 portion of the map area, a cluster of about 20 pipes and dikes, many with truncated tops, record eight stratigraphically distinct seismic events. The large dunes that deposited the Navajo cross-strata likely moved ~1m/yr. When, in response to seismic shaking, a few liters of fluidized sand erupted onto the lowermost portion of the dune lee slope through a pipe, the erupted sand dried and was buried by climbing wind-ripple strata as the large dune continued to advance downwind. The mapped cluster recording eight distinct seismic events lies within thin-laminated sediment that was deposited by wind ripples during 1 m (~ 1 year) of southeastward dune migration. We conclude that the small pipes and dikes of our study sites are products of numerous >MM 5 earthquakes, some of which recurred at intervals of less than 2 months. We interpret one small cluster of pipes and dikes with well-defined upward terminations as a distinct shock-aftershock sequence. Because the largest modern earthquakes can produce surface liquefaction only up to about 175 km from their epicenters, the Jurassic epicenters must have been well within that distance. The tendency of modern plate boundaries to produce high-frequency aftershocks suggests that the epicenter for this Jurassic sequence lay to the southwest, within the plate boundary zone (not within continental rocks to the east). As eolian dunes steadily migrate over interdune surfaces underlain by water-saturated dune cross-strata, the thin, distinct laminae produced by the wind ripples that occupy dune toes can faithfully record high-frequency seismic events.

Similar simulation study on the characteristics of the electric potential response to coal mining

NASA Astrophysics Data System (ADS)

Niu, Yue; Li, Zhonghui; Kong, Biao; Wang, Enyuan; Lou, Quan; Qiu, Liming; Kong, Xiangguo; Wang, Jiali; Dong, Mingfu; Li, Baolin

2018-02-01

An electric potential (EP) can be generated during the failure process of coal and rock. In this article, a similar physical model of coal rock was built and the characteristics of the EP responding to the process of coal mining were studied. The results showed that, at the early mining stage, the structure of coal rock strata were stable in the simulation model, the support stress of overlying coal rock strata was low and the maximum subsidence was little, while the EP change was less. With the advancement of the working face, the support stress of the overlying coal rock strata in the mined-out area changed dramatically, the maximum subsidence increased constantly, the deformation and destruction were aggravated, and cracks expanded continuously. Meanwhile, the EP response was significant with fluctuation. When significant macro damage appeared in coal rock strata, the EP signal fluctuation was violent. The overlying coal rock strata were influenced by gravity and mining activity. During the mining process, the crack growth and the friction, together with slip between coal and rock particles, resulted in the response of EP. The change in EP was closely related to the damage state and stress distribution of the coal rock strata. EP monitoring has the advantages of accurate reflection and strong anti-interference in the field. Therefore, with further study, an EP monitoring method could be applied for monitoring and early warning of coal and rock dynamic disaster, and risk evaluation in the future. The strength of the EP and its fluctuation degree could serve as the key discrimination indexes.

Comparative Genomics of Mycobacteria: Some Answers, Yet More New Questions

PubMed Central

Behr, Marcel A.

2015-01-01

Comparative genomic studies permit a genus-level perspective on the distinction between environmental mycobacteria and Mycobacterium tuberculosis, as well as a species-level assessment of genetic variability within M. tuberculosis. Both of these strata of evolutionary analysis serve to generate hypotheses regarding the genomic basis of M. tuberculosis virulence. In contrasting lessons from macroevolutionary study and microevolutionary study, one can form predictions about which segments of the genome are likely to be essential for or dispensable for the pathogenesis of tuberculosis. Although some of these predictions have been experimentally verified, notable exceptions challenge the direct link between these virulence factors and the capacity of M. tuberculosis to successfully cause disease and propagate between human hosts. These unexpected findings serve as the stimulus for further studies, using genomic comparisons and other approaches, to better define the remarkable success of this recalcitrant pathogen. PMID:25395374

Aerodynamic effects of nearly uniform slipstreams on thin wings in the transonic regime

NASA Technical Reports Server (NTRS)

Rizk, M. H.

1980-01-01

A simplified model is used to describe the interaction between a propeller slipstream and a wing in the transonic regime. The undisturbed slipstream boundary is assumed to coincide with an infinite circular cylinder. The undisturbed slipstream velocity is rotational and is a function of the radius only. In general, the velocity perturbation caused by introducing a wing into the slipstream is also rotational. By making small disturbance assumptions, however, the perturbation velocity becomes nearly potential, and an approximation for the flow is obtained by solving a potential equation.

Remote sensing applications for urban planning - The LUMIS project. [Land Use Management Information System

NASA Technical Reports Server (NTRS)

Paul, C. K.; Landini, A. J.; Diegert, C.

1975-01-01

The Santa Monica mountains of Los Angeles consist primarily of complexly folded sedimentary marine strata with igneous and metamorphic rocks at the eastern end of the mountains. With the increased development of the Santa Monicas, a study was conducted to determine the critical land use data items in the mountains. Two information systems developed in parallel are described. One capitalizes on the City's present computer line printer system, and the second utilizes map overlay techniques on an interactive computer terminal. Results concerning population, housing, and land improvement illustrate the successful linking of ordinal and nominal data files in the interactive system.-

Depositional sequences and facies in the Torok Formation, National Petroleum Reserve, Alaska (NPRA)

USGS Publications Warehouse

Houseknecht, David W.; Schenk, Christopher J.

2002-01-01

Brookian turbidites (Cretaceous through Tertiary) have become oil exploration objectives on the NorthSlope of Alaska during the past decade, and it is likely this focus will extend into the National Petroleum Reserve-Alaska (NPRA). A regional grid of 2-D seismic data, sparse well control, and field work in the Brooks Range foothills provide constraints for an ongoing effort to establish a sequence stratigraphic framework for Brookian turbidites in the Torok Formation across NPRA. The Torok Formation and overlying Nanushuk Formation (both mostly Albian) display the overall seismic geometry of bottomset-clinoform-topset strata indicating northeastward migration of a shelf margin. Within bottomset and clinoform strata of the Torok, depositional sequences have been identified that represent four distinct phases of shelf-margin sedimentation. (1) Regression, representing low relative sea level, is characterized by the development of an erosional surface on the shelf and upper slope, and the deposition of turbidite channel deposits on the middle to lower slope and submarine fan deposits at the base of slope. These deposits constitute a lowstand systems tract (LST). (2) Transgression, representing rising relative sea level, is characterized by the deposition of a mudstone drape on the basin floor, slope, and outer shelf. This drape comprises relatively condensed facies that constitute a transgressive systems tract (TST). (3) Aggradation, representing high relative sea level, is characterized by the deposition of relatively thick strata on the outer shelf and moderately thick mudstones on the slope. (4) Progradation, also representing high relative sea level, is characterized by the deposition of relatively thin strata on the outer shelf and very thick mudstones on the slope. Together, deposits of the aggradation and progradation phases constitute a highstand systems tract (HST). Large scale geometries of Torok strata vary across the Colville basin. In southern NPRA, high rates of subsidence accommodated the deposition of a "foredeep clinoform wedge" that contains a high proportion of sand-rich LST deposits. In northern NPRA, lower rates of subsidence favored the accumulation of mud-rich HST deposits. The most favorable stratigraphic trapping geometries in the Torok Formation occur where amalgamated sandstones deposited in turbidite channels incised on the mid- to lower-slope and on the proximal parts of submarine fans during regression (LSTs) are capped by relatively condensed mudstone facies deposited during transgression (TSTs). Common successions observed in Torok cores include a spectrum of slope and turbidite facies. Upper slope facies comprise laminated mudstones and siltstones that locally display evidence of slumping, sliding, and chaotic failure. Lower slope facies comprise heterolithic turbidites at some locations and interlaminated mudstones and thin, very fine-grained sandstones at others. Torok turbidites include amalgamated sandstones deposited in channel systems as well as thin-bedded, widespread sandstones deposited by unconfined flows on lobes or in channel overbank settings. These turbidite facies likely occur in both channel-lobe systems and slope apron systems within the Torok.

Development of a rockfall hazard rating matrix for the State of Ohio : executive summary report.

DOT National Transportation Integrated Search

2005-06-30

The geology in Ohio is characterized by the : presence of gently dipping, harder, more competent : strata (siltstones, sandstones, limestones) alternating : with softer, less competent strata (claystones, : mudstones, sha les). This type of stratigra...

Areal Control Using Generalized Least Squares As An Alternative to Stratification

Treesearch

Raymond L. Czaplewski

2001-01-01

Stratification for both variance reduction and areal control proliferates the number of strata, which causes small sample sizes in many strata. This might compromise statistical efficiency. Generalized least squares can, in principle, replace stratification for areal control.

Development of a Rockfall Hazard Rating Matrix for the State of Ohio : Executive Summary Report

DOT National Transportation Integrated Search

2005-06-01

The geology in Ohio is characterized by the : presence of gently dipping, harder, more competent : strata (siltstones, sandstones, limestones) alternating : with softer, less competent strata (claystones, : mudstones, sha les). This type of stratigra...

Raster Images of Geologic Maps of Middle Proterozoic Belt strata in parts of Benewah, Bonner, Kootenai and Shoshone Counties, Idaho and Lincoln, Mineral and Sanders Counties, Montana

USGS Publications Warehouse

Boleneus, David E.; Appelgate, Larry M.; Joseph, Nancy L.; Brandt, Theodore R.

2001-01-01

Geologic maps of the western part of the Belt Basin of western Montana and northern Idaho were converted into digital raster (TIFF image) format to facilitate their manipulation in geographic information systems. The 85-mile x 100-mile map area mostly contains rocks belonging to the lower and middle Belt Supergroup. The area is of interest as these Middle Proterozoic strata contain vein-type lead-zinc-silver deposits in the Coeur d?Alene Mining District in the St. Regis and Revett formations and strata-bound copper-silver deposits, such as the Troy mine, within the Revett Formation. The Prichard Formation is also prospective for strata-bound lead-zinc deposits because equivalent Belt strata in southern British Columbia, Canada host the Sullivan lead-zinc deposit. Map data converted to digital images include 13 geological maps at scales ranging from 1:48,000 to 1:12,000. Geologic map images produced from these maps by color scanning were registered to grid tick coverages in a Universal Transverse Mercator (North American Datum of 1927, zone 11) projection using ArcView Image Analysis. Geo-registering errors vary from 10 ft to 114 ft.

Chlorophyll a and inorganic suspended solids in backwaters of the upper Mississippi River system: Backwater lake effects and their associations with selected environmental predictors

USGS Publications Warehouse

Rogala, James T.; Gray, Brian R.

2006-01-01

The Long Term Resource Monitoring Program (LTRMP) uses a stratified random sampling design to obtain water quality statistics within selected study reaches of the Upper Mississippi River System (UMRS). LTRMP sampling strata are based on aquatic area types generally found in large rivers (e.g., main channel, side channel, backwater, and impounded areas). For hydrologically well-mixed strata (i.e., main channel), variance associated with spatial scales smaller than the strata scale is a relatively minor issue for many water quality parameters. However, analysis of LTRMP water quality data has shown that within-strata variability at the strata scale is high in off-channel areas (i.e., backwaters). A portion of that variability may be associated with differences among individual backwater lakes (i.e., small and large backwater regions separated by channels) that cumulatively make up the backwater stratum. The objective of the statistical modeling presented here is to determine if differences among backwater lakes account for a large portion of the variance observed in the backwater stratum for selected parameters. If variance associated with backwater lakes is high, then inclusion of backwater lake effects within statistical models is warranted. Further, lakes themselves may represent natural experimental units where associations of interest to management may be estimated.

Geologic map of the Glen Canyon Dam 30’ x 60’ quadrangle, Coconino County, northern Arizona

USGS Publications Warehouse

Billingsley, George H.; Priest, Susan S.

2013-01-01

The Glen Canyon Dam 30’ x 60’ quadrangle is characterized by nearly flat lying to gently dipping Paleozoic and Mesozoic sedimentary strata that overlie tilted Proterozoic strata or metasedimentary and igneous rocks similar to those exposed at the bottom of Grand Canyon southwest of the quadrangle. Mississippian to Permian rocks are exposed in the walls of Marble Canyon; Permian strata and minor outcrops of Triassic strata form the surface bedrock of House Rock Valley and Marble Plateau, southwestern quarter of the quadrangle. The Paleozoic strata exposed in Marble Canyon and Grand Canyon south of the map are likely present in the subsurface of the entire quadrangle but with unknown facies and thickness changes. The Mesozoic sedimentary rocks exposed along the Vermilion and Echo Cliffs once covered the entire quadrangle, but Cenozoic erosion has removed most of these rocks from House Rock Valley and Marble Plateau areas. Mesozoic strata remain over much of the northern and eastern portions of the quadrangle where resistant Jurassic sandstone units form prominent cliffs, escarpments, mesas, buttes, and much of the surface bedrock of the Paria, Kaibito, and Rainbow Plateaus. Jurassic rocks in the northeastern part of quadrangle are cut by a sub-Cretaceous regional unconformity that bevels the Entrada Sandstone and Morrison Formation from Cummings Mesa southward to White Mesa near Kaibito. Quaternary deposits, mainly eolian, mantle much of the Paria, Kaibito, and Rainbow Plateaus in the northern and northeastern portion of the quadrangle. Alluvial deposits are widely distributed over parts of House Rock Valley and Marble Plateau in the southwest quarter of the quadrangle. The east-dipping strata of the Echo Cliffs Monocline forms a general north-south structural boundary through the central part of the quadrangle, separating Marble and Paria Plateaus west of the monocline from the Kaibito Plateau east of the monocline. The Echo Cliffs Monocline continues north of the quadrangle into southern Utah. The gentle north- and northeast-dipping Mesozoic strata on the Kaibito and Rainbow Plateaus are partly interrupted by northwest-trending, broad-based, ill-defined synclines and anticlines. These broad-based structures form mesas and buttes near anticlinal crests and deeply incised drainages in synclinal valleys. The 1,300-ft-thick (396-m-thick) Navajo Sandstone erodes into a maze of tributary slot canyons in the northeastern part of the quadrangle. Mesozoic strata in the extreme northeast corner of the quadrangle dip gently southwest due to the influence of the Monument Upwarp in southeastern Utah and by an intrusive uplift (laccolith) that forms Navajo Mountain, a prominent 10,388 ft (3,166 m) landmark just northeast of the quadrangle.

Bromus tectorum invasion alters nitrogen dynamics in an undisturbed arid grassland ecosystem

USGS Publications Warehouse

Sperry, L.J.; Belnap, J.; Evans, R.D.

2006-01-01

The nonnative annual grass Bromus tectorum has successfully replaced native vegetation in many arid and semiarid ecosystems. Initial introductions accompanied grazing and agriculture, making it difficult to separate the effects of invasion from physical disturbance. This study examined N dynamics in two recently invaded, undisturbed vegetation associations (C3 and C4). The response of these communities was compared to an invaded/disturbed grassland. The invaded/disturbed communities had higher surface NH4+ input in spring, whereas there were no differences for surface input of NO3-. Soil inorganic N was dominated by NH4+, but invaded sites had greater subsurface soil NO3-. Invaded sites had greater total soil N at the surface four years post-invasion in undisturbed communities, but total N was lower in the invaded/disturbed communities. Soil ??15N increased with depth in the noninvaded and recently invaded communities, whereas the invaded/disturbed communities exhibited the opposite pattern. Enriched foliar ??15N values suggest that Bromus assimilated subsurface NO3-, whereas the native grasses were restricted to surface N. A Rayleigh distillation model accurately described decomposition patterns in the noninvaded communities where soil N loss is accompanied by increasing soil ??15N; however, the invaded/disturbed communities exhibited the opposite pattern, suggesting redistribution of N within the soil profile. This study suggests that invasion has altered the mechanisms driving nitrogen dynamics. Bromus litter decomposition and soil NO3- concentrations were greater in the invaded communities during periods of ample precipitation, and NO3- leached from the surface litter, where it was assimilated by Bromus. The primary source of N input in these communities is a biological soil crust that is removed with disturbance, and the lack of N input by the biological soil crust did not balance N loss, resulting in reduced total N in the invaded/disturbed communities. Bromus produced a positive feedback loop by leaching NO3- from decomposing Bromus litter to subsurface soil layers, accessing that deep-soil N pool with deep roots and returning that N to the surface as biomass and subsequent litter. Lack of new inputs combined with continued loss will result in lower total soil N, evidenced by the lower total soil N in the invaded/disturbed communities. ?? 2006 by the Ecological Society of America.

Facies architecture and stratigraphic evolution of aeolian dune and interdune deposits, Permian Caldeirão Member (Santa Brígida Formation), Brazil

NASA Astrophysics Data System (ADS)

Jones, Fábio Herbert; Scherer, Claiton Marlon dos Santos; Kuchle, Juliano

2016-05-01

The Permian Caldeirão Member (Santa Brígida Formation), located in the Tucano Central Basin, northeast region of Brazil, is characterized by a sandstone succession of aeolian origin that comprises the preserved deposits of dunes and interdunes. Grainflow and translatent wind-ripple strata, and frequent presence of reactivation surface, compose the cross-bedding of crescent aeolian dune deposits. The aeolian cross-strata show a mean dip toward the ENE. In places, interlayered with dune cross-beds, occur interdune units composed of facies indicative of dry, damp and wet condition of the substrate, suggesting spatial and/or temporal variations in the moisture content of the interdune accumulation surface. The presence of NNW current ripple cross-lamination in wet interdune areas indicates streamflows confined to interdune corridors and oriented perpendicular to aeolian transport direction. Lenses of damp and wet interdune strata exhibit mainly interdigitated and transitional relationships with the toe-sets of overlying aeolian dune units in sections parallel to aeolian transport, indicating that dune migration was contemporaneous with accumulation in adjacent interdunes. Lateral variations in the preserved thickness of the interdune units and the associated rare occurrence of abrupt and erosive contacts between interdune and overlying dune sets, suggest temporal variations in the angle of dune and interdune climb that may be related to high-frequency changes in water table position. Four stratigraphic intervals in the Caldeirão Member can be identified, two intervals showing cross-bedding of aeolian dunes without wet interdune areas and two intervals exhibiting aeolian dunes separated by wet interdune areas, marking the transition between dry aeolian systems (Intervals I and III) and wet aeolian systems (Intervals II and IV). The temporal alternations between dry and wet aeolian systems reflect changes in the availability of dry sand and/or the rate in the water table rise, possibly controlled by orbitally-driven climatic fluctuations.

Assessing Seedling Recruitment in Retrogressive Thaw Slumps in the Alaskan Low Arctic

NASA Astrophysics Data System (ADS)

Huebner, D. C.; Bret-Harte, M. S.

2016-12-01

Thermal erosion of permafrost soils may promote shifts from moist acidic tussock tundra (MAT) to shrub tundra in the Alaskan Low Arctic. Tall birch and willow shrub thickets (>1 m) have been observed in stabilized retrogressive thaw slumps (RTS) caused by thermal erosion near lake margins. RTS contain unvegetated, sheltered microsites, which may revegetate through seedling recruitment. We assessed whether recruitment in RTS was greater than in undisturbed MAT by measuring increased seedling cover and seedbank viability. We expected that seedbanks would show post-RTS tradeoffs in quantity and quality, with young seedbanks containing fewer, mostly viable seeds whose viability would decrease as seeds accumulate after disturbance. We made pairwise comparisons of in-situ seedling counts, seedbank viability (percent germination), and seed density (seeds m-2) of soil seedbanks across a chronosequence of RTS and nearby undisturbed MAT (n = 8 sample areas) at two sites near Toolik Lake, Alaska. Both RTS chronosequences were aged in a previous study through shrub ring counts and radiocarbon dated peat. RTS included young (1-10 years after disturbance), middle-aged (10-29 years) and old (> 30 years) sites. Undisturbed MAT areas were not aged but were likely undisturbed by RTS for > 300 years. We found 6 to 40 times more in-situ seedlings in younger RTS than in older RTS, and no seedlings in undisturbed MAT. Younger RTS had more willow and birch seedlings than older RTS. Higher in-situ seedling counts were correlated with deeper thaw depths, more bare soil, and decreased elevation, which suggested sheltering effects. Seedbank viability was unrelated to seedbank size or in-situ counts. Seedbank size increased with age at only one RTS site with no difference in percent germination. At the other site, percent germination decreased with age, but seedbank size was not different. Willow and birch germination was 1-2% overall. Site differences in seedbank size, viability, and species composition indicate that local variation may shape seedbank properties. Our results suggest that RTS in the Alaskan Low Arctic may facilitate greater seedling recruitment, which may in part explain the occurrence of tall shrub thickets in RTS.

Fish assemblages in Tanzanian mangrove creek systems influenced by solar salt farm constructions

NASA Astrophysics Data System (ADS)

Mwandya, Augustine W.; Gullström, Martin; Öhman, Marcus C.; Andersson, Mathias H.; Mgaya, Yunus D.

2009-04-01

Deforestation of mangrove forests is common occurrence worldwide. We examined fish assemblage composition in three mangrove creek systems in Tanzania (East Africa), including two creeks where the upper parts were partly clear-cut of mangrove forest due to the construction of solar salt farms, and one creek with undisturbed mangrove forest. Fish were caught monthly for one year using a seine net (each haul covering 170 m 2) within three locations in each creek, i.e. at the upper, intermediate and lower reaches. Density, biomass and species number of fish were lower in the upper deforested sites compared to the mangrove-fringed sites at the intermediate and lower parts in the two creeks affected by deforestation, whereas there were no differences among the three sites in the undisturbed mangrove creek system. In addition, multivariate analyses showed that the structure of fish assemblages varied between forested and clear-cut sites within the two disturbed creeks, but not within the undisturbed creek. Across the season, we found no significant differences except for a tendency of a minor increase in fish densities during the rainy season. At least 75% of the fishes were juveniles and of commercial interest for coastal fisheries and/or aquaculture. Mugil cephalus, Gerres oyena and Chanos chanos were the most abundant species in the forested sites. The dominant species in the clear-cut areas were M. cephalus and Elops machnata, which were both found in relatively low abundances compared to the undisturbed areas. The conversion of mangrove forests into solar salt farms not only altered fish assemblage composition, but also water and sediment conditions. In comparison with undisturbed areas, the clear-cut sites showed higher salinity, water temperature as well as organic matter and chlorophyll a in the sediments. Our results suggest that mangrove habitat loss and changes in environmental conditions caused by salt farm developments will decrease fish densities, biomass and species numbers as well as alter the overall fish assemblage composition in the salt farm area but not downstream in the creek.

Stratigraphic and palaeoenvironmental summary of the south-east Georgia embayment: a correlation of exploratory wells

USGS Publications Warehouse

Poppe, Lawrence J.; Popenoe, Peter; Poag, C. Wylie; Swift, B. Ann

1995-01-01

A Continental Offshore Stratigraphic Test (COST) well and six exploratory wells have been drilled in the south-east Georgia embayment. The oldest rocks penetrated are weakly metamorphosed Lower Ordovician quartz arenites and Silurian shales and argillites in the Transco 1005-1 well and Upper Devonian argillites in the COST GE-1 well. These marine strata, which are equivalent to the Tippecanoe sequence in Florida, underlie the post-rift unconformity and represent part of a disjunct fragment of Gondwana that was sutured to the North American craton during the late Palaeozoic Alleghanian orogeny. The Palaeozoic strata are unconformably overlain by interbedded non-marine Jurassic (Bajocian and younger) sandstones and shales and marginal marine Lower Cretaceous sandstones, calcareous shales and carbonates, which contain scattered beds of coal and evaporite. Together, these rocks are stratigraphically equivalent to the onshore Fort Pierce and Cotton Valley(?) Formations and rocks of the Lower Cretaceous Comanchean Provincial Series. The abundance of carbonates and evaporites in this interval, which reflects marine influences within the embayment, increases upwards, eastwards and southwards. The Upper Cretaceous part of the section is composed mainly of neritic calcareous shales and shaley limestones stratigraphically equivalent to the primarily marginal marine facies of the onshore Atkinson, Cape Fear and Middendorf Formations and Black Creek Group, and to limestones and shales of the Lawson Limestone and Peedee Formations. Cenozoic strata are primarily semiconsolidated marine carbonates. Palaeocene to middle Eocene strata are commonly cherty; middle Miocene to Pliocene strata are massive and locally phosphatic and glauconitic; Quaternary sediments are dominated by unconsolidated carbonate sands. The effects of eustatic changes and shifts in the palaeocirculation are recorded in the Upper Cretaceous and Tertiary strata.

A new species of Dyoros (Brachiopoda; Chonetoidea) from Nevada (United States) and stratigraphic implications for the Pennsylvanian and Permian Antler Overlap assemblage [Une nouvelle espèce de Dyoros (Brachiopoda; Chonetoidea) du Nevada (États-Unis) et implications stratigraphiques pour le Complexe chevauchant d'Antler (Pennsylvanien et Permien)

USGS Publications Warehouse

Racheboeuf, Patrick R.; Moore, Thomas E.; Blodgett, Robert B.

2004-01-01

Newly discovered fossil localities in coarse-grained deposits of the Pennsylvanian and Permian Antler overlap assemblage in the southern Shoshone Range, north-central Nevada have yielded a low-diversity assemblage consisting chiefly of a new species of chonetoidean brachiopod: Dyoros (Lissosia) nevadaensis nov. sp. The subgenus Dyoros (Lissosia), is known from Leonardian and lower Guadalupian strata in North America, mainly in Texas. The coarse-grained lithology of the host strata, their unconformable relation on deformed lower Paleozoic rocks, and the Leonardian and(or) lower Guadalupian age indicated by Dyoros (Lissosia) provide evidence that host strata are younger than strata of the Antler overlap assemblage in nearby areas of the southern Shoshone Range and suggest that an unconformity of local extent may be present within the overlap assemblage. The fossil age ranges and lithologic data suggest that the host strata may be correlative with the Guadalupian Edna Mountain Formation, an unconformity-bounded unit that forms the upper part of the Antler sequence in the Battle Mountain area to the north. This correlation suggests that the unconformity beneath these strata may have regional extent in north-central Nevada. The origin of the inferred regional unconformity is unknown and may have resulted from relative changes of sea level or regional extensional or contractional tectonism in the area of the former Antler highlands, which forms the substrate for the Antler overlap assemblage. ?? 2004 Elsevier SAS. All rights reserved.

An integrated geophysical study on the Mesozoic strata distribution and hydrocarbon potential in the South China Sea

NASA Astrophysics Data System (ADS)

Hu, Weijian; Hao, Tianyao; Jiang, Weiwei; Xu, Ya; Zhao, Baimin; Jiang, Didi

2015-11-01

A series of drilling, dredge, and seismic investigations indicate that Mesozoic sediments exist in the South China Sea (SCS) which shows a bright prospect for oil and gas exploration. In order to study the distribution of Mesozoic strata and their residual thicknesses in the SCS, we carried out an integrated geophysical study based mainly on gravity data, gravity basement depth and distribution of residual Mesozoic thickness in the SCS were obtained using gravity inversion constrained with high-precision drilling and seismic data. In addition, the fine deep crustal structures and distribution characteristics of Mesozoic thicknesses of three typical profiles were obtained by gravity fitting inversion. Mesozoic strata in the SCS are mainly distributed in the south and north continental margins, and have been reformed by the later tectonic activities. They extend in NE-trending stripes are macro-controlled by the deep and large NE-trending faults, and cut by the NW-trending faults which were active in later times. The offset in NW direction of Mesozoic strata in Nansha area of the southern margin are more obvious as compared to the north margin. In the Pearl River Mouth Basin and Southwest Taiwan Basin of the north continental margin the Mesozoic sediments are continuously distributed with a relatively large thickness. In the Nansha area of the south margin the Mesozoic strata are discontinuous and their thicknesses vary considerably. According to the characteristics of Mesozoic thickness distribution and hydrocarbon potential analyses from drilling and other data, Dongsha Uplift-Chaoshan Depression, Southwest Taiwan Basin-Peikang Uplift and Liyue Bank have large thickness of the Mesozoic residual strata, have good hydrocarbon genesis capability and complete source-reservoir-cap combinations, show a bright prospect of Mesozoic oil/gas resources.

Assessment the effect of homogenized soil on soil hydraulic properties and soil water transport

NASA Astrophysics Data System (ADS)

Mohawesh, O.; Janssen, M.; Maaitah, O.; Lennartz, B.

2017-09-01

Soil hydraulic properties play a crucial role in simulating water flow and contaminant transport. Soil hydraulic properties are commonly measured using homogenized soil samples. However, soil structure has a significant effect on the soil ability to retain and to conduct water, particularly in aggregated soils. In order to determine the effect of soil homogenization on soil hydraulic properties and soil water transport, undisturbed soil samples were carefully collected. Five different soil structures were identified: Angular-blocky, Crumble, Angular-blocky (different soil texture), Granular, and subangular-blocky. The soil hydraulic properties were determined for undisturbed and homogenized soil samples for each soil structure. The soil hydraulic properties were used to model soil water transport using HYDRUS-1D.The homogenized soil samples showed a significant increase in wide pores (wCP) and a decrease in narrow pores (nCP). The wCP increased by 95.6, 141.2, 391.6, 3.9, 261.3%, and nCP decreased by 69.5, 10.5, 33.8, 72.7, and 39.3% for homogenized soil samples compared to undisturbed soil samples. The soil water retention curves exhibited a significant decrease in water holding capacity for homogenized soil samples compared with the undisturbed soil samples. The homogenized soil samples showed also a decrease in soil hydraulic conductivity. The simulated results showed that water movement and distribution were affected by soil homogenizing. Moreover, soil homogenizing affected soil hydraulic properties and soil water transport. However, field studies are being needed to find the effect of these differences on water, chemical, and pollutant transport under several scenarios.

Using Grain-Size Distribution Methods for Estimation of Air Permeability.

PubMed

Wang, Tiejun; Huang, Yuanyang; Chen, Xunhong; Chen, Xi

2016-01-01

Knowledge of air permeability (ka ) at dry conditions is critical for the use of air flow models in porous media; however, it is usually difficult and time consuming to measure ka at dry conditions. It is thus desirable to estimate ka at dry conditions from other readily obtainable properties. In this study, the feasibility of using information derived from grain-size distributions (GSDs) for estimating ka at dry conditions was examined. Fourteen GSD-based equations originally developed for estimating saturated hydraulic conductivity were tested using ka measured at dry conditions in both undisturbed and disturbed river sediment samples. On average, the estimated ka from all the equations, except for the method of Slichter, differed by less than ± 4 times from the measured ka for both undisturbed and disturbed groups. In particular, for the two sediment groups, the results given by the methods of Terzaghi and Hazen-modified were comparable to the measured ka . In addition, two methods (e.g., Barr and Beyer) for the undisturbed samples and one method (e.g., Hazen-original) for the undisturbed samples were also able to produce comparable ka estimates. Moreover, after adjusting the values of the coefficient C in the GSD-based equations, the estimation of ka was significantly improved with the differences between the measured and estimated ka less than ±4% on average (except for the method of Barr). As demonstrated by this study, GSD-based equations may provide a promising and efficient way to estimate ka at dry conditions. © 2015, National Ground Water Association.

Carboniferous and older carbonate rocks: Lithofacies, extent, and reservoir quality: Chapter CC in The oil and gas resource potential of the Arctic National Wildlife Refuge 1002 area, Alaska

USGS Publications Warehouse

Dumoulin, Julie A.

1999-01-01

Carboniferous and older carbonate rocks are potential hydrocarbon reservoir facies for four plays in the 1002 area of the Arctic National Wildlife Refuge. These rocks include several units in the pre-Carboniferous basement and the Carboniferous Lisburne Group. Data from exploratory wells west of the 1002 area, outcrops south of the 1002 area, seismic lines, and well logs are synthesized herein to infer carbonate lithofacies, extent, and reservoir character beneath the northeastern Arctic coastal plain.A chiefly shallow-water basement carbonate succession of Late Proterozoic through Early Devonian age (Katakturuk Dolomite, Nanook Limestone, and Mount Copleston Limestone) is interpreted to be present beneath much of the south-central 1002 area; it reaches 3,700 m thick in outcrop and is the primary reservoir for the Deformed Franklinian Play. A more heterogeneous lithologic assemblage of uncertain age forms basement in the northwestern part of the 1002 area; well data define three subunits that contain carbonate intervals 5- 50 m thick. These strata are prospective reservoirs for the Undeformed Franklinian Play and could also be reservoirs for the Niguanak- Aurora Play. Regional lithologic correlations suggest a Cambrian-Late Proterozoic(?) age for subunits one and two, and a slightly younger, later Cambrian-Silurian age for subunit three. Seismic and well data indicate that subunit one overlies subunit two and is overlain by subunit three. The Mississippian and Pennsylvanian Lisburne Group, a predominantly carbonate platform succession as much as 1 km thick, is projected beneath the southernmost part of the 1002 area and is a potential reservoir for the Ellesmerian Thrust-belt and Niguanak-Aurora Plays.Carbonate rocks in the 1002 area probably retain little primary porosity but may have locally well developed secondary porosity. Measured reservoir parameters in basement carbonate strata are low (porosity generally ≤ 5%; permeability ≤ 0.2 md) but drill-stem tests found locally reasonable flow rates (4,220-4,800 bpd) and, in the Flaxman Island area, recovered gas and condensate from these rocks. The Lisburne Group has produced up to 50,000 bbl of oil/ day from the Lisburne field at Prudhoe Bay. Reservoir parameters of the Lisburne in northeastern Alaska range from low (porosities ≤ 5% in most limestones) to good (porosities average 6.5-10% in some dolostones). Reservoir quality in Carboniferous and older carbonate strata in the 1002 area should be greatest where these rocks are highly fractured and (or) truncated by the Lower Cretaceous Unconformity.

Tooth autotransplantation in a free iliac crest graft for prosthetic reconstruction.

PubMed

Landes, Constantin A; Glasl, Bettina; Ludwig, Björn; Rieger, Jörg; Sader, Robert

2008-09-01

This report documents successful tooth autotransplantation to a free iliac crest graft in an exemplar case. A 14-year-old male patient was operated thrice with increasing amounts of resection for recurrent odontogenic myxoma. When mandibular continuity resection finally was performed, a free iliac crest block autotransplant was used for reconstruction. Upon metal removal 5 months later, 3 wisdom teeth with two-thirds complete root development were transplanted to the free graft and retained by fixed orthodontic appliances including skeletal anchorage with orthodontic microscrews. Tooth graft taking was awaited for 8 weeks with retention. Following undisturbed healing without occlusal forces, 6 months of orthodontic treatment intentionally extruded the autotransplanted teeth to antagonist contact. The third and most dorsal tooth became mobile after 3 months and was lost. The surviving 2 teeth were fitted by a prosthetic bridge as extrusion into the occlusal plane was not completely successful. This exemplar case shows benefit of tooth autotransplants in selected cases of jaw reconstruction with distal bone autotransplants as alternative to dental titanium implants and suprastructures. Orthodontic microscrews can moreover support tooth movement and positioning as anchorage device in altered anatomy.

Capture-recapture studies for multiple strata including non-markovian transitions

USGS Publications Warehouse

Brownie, C.; Hines, J.E.; Nichols, J.D.; Pollock, K.H.; Hestbeck, J.B.

1993-01-01

We consider capture-recapture studies where release and recapture data are available from each of a number of strata on every capture occasion. Strata may, for example, be geographic locations or physiological states. Movement of animals among strata occurs with unknown probabilities, and estimation of these unknown transition probabilities is the objective. We describe a computer routine for carrying out the analysis under a model that assumes Markovian transitions and under reduced parameter versions of this model. We also introduce models that relax the Markovian assumption and allow 'memory' to operate (i.e., allow dependence of the transition probabilities on the previous state). For these models, we sugg st an analysis based on a conditional likelihood approach. Methods are illustrated with data from a large study on Canada geese (Branta canadensis) banded in three geographic regions. The assumption of Markovian transitions is rejected convincingly for these data, emphasizing the importance of the more general models that allow memory.

Logging affects fledgling sex ratios and baseline corticosterone in a forest songbird.

PubMed

Leshyk, Rhiannon; Nol, Erica; Burke, Dawn M; Burness, Gary

2012-01-01

Silviculture (logging) creates a disturbance to forested environments. The degree to which forests are modified depends on the logging prescription and forest stand characteristics. In this study we compared the effects of two methods of group-selection ("moderate" and "heavy") silviculture (GSS) and undisturbed reference stands on stress and offspring sex ratios of a forest interior species, the Ovenbird (Seiurus aurocapilla), in Algonquin Provincial Park, Canada. Blood samples were taken from nestlings for corticosterone and molecular sexing. We found that logging creates a disturbance that is stressful for nestling Ovenbirds, as illustrated by elevated baseline corticosterone in cut sites. Ovenbirds nesting in undisturbed reference forest produce fewer male offspring per brood (proportion male = 30%) while logging with progressively greater forest disturbance, shifted the offspring sex ratio towards males (proportion male: moderate = 50%, heavy = 70%). If Ovenbirds in undisturbed forests usually produce female-biased broods, then the production of males as a result of logging may disrupt population viability. We recommend a broad examination of nestling sex ratios in response to anthropogenic disturbance to determine the generality of our findings.

Distribution and Origin of Iridium in Upper Triassic-Lower Jurassic Continental Strata of the Fundy, Deerfield and Hartford Basins, Newark Supergroup

NASA Astrophysics Data System (ADS)

Tanner, L. H.; Kyte, F. T.

2015-12-01

To date, elevated Ir levels in continental sediments proximal to the Triassic-Jurassic boundary (TJB) have been reported only from Upper Triassic strata of the Newark and Fundy basins, below the basal extrusive units of the Central Atlantic Magmatic Province. We report here the first occurrence of elevated Ir above the oldest volcanic units, as well as additional horizons of Ir enrichment from other basins of the Newark Supergroup. In the Fundy Basin (Nova Scotia, Canada), lacustrine sediments of the Scots Bay Member of the McCoy Brook Formation that directly overlie the North Mountain Basalt contain Ir up to 413 pg/g in fish-bearing strata very close to the palynological TJB. Higher in the formation the strata lack significant Ir enrichment. Similarly, sedimentary strata from between flows of North Mount Basalt show no Ir appreciable enrichment. The Deerfield Basin (Massachusetts) extension of the Hartford Basin contains only one CAMP extrusive unit, the Lower Jurassic Deerfield Basalt. Very modest Ir enrichment, up to 90 pg/g, occurs in the Fall River Beds of the Sugarloaf Formation, several meters below the basalt, and up to 70 pg/g in the Turners Falls Formation less than 2 meters above the basalt. The uppermost New Haven Formation (Upper Triassic) at the Silver Ridge locality (Guilford, CT) in the Hartford Basin contains abundant plant debris, but no evidence of elevated Ir. At the Clathopteris locality to the north (Holyoke, MA), potentially correlative strata that are fine grained and rich in plant remains have Ir enriched to 542 pg/g, an order of magnitude higher than in the coarser-grained strata in direct stratigraphic contact. The high-Ir beds also have elevated REEs relative to other Hartford Basin samples, although there is no evidence of HREE enrichment. We consider the basalts of the Central Atlantic Magmatic Province, widely accepted as the driver of Late Triassic extinctions, as the origin of the elevated Ir levels in the Newark Supergroup.

Cretaceous rocks from southwestern Montana to southwestern Minnesota, northern Rocky Mountains, and Great Plains

USGS Publications Warehouse

Dyman, T.S.; Cobban, W.A.; Fox, J.E.; Hammond, R.H.; Nichols, D.J.; Perry, W.J.; Porter, K.W.; Rice, D.D.; Setterholm, D.R.; Shurr, G.W.; Tysdal, R.G.; Haley, J.C.; Campen, E.B.

1994-01-01

In Montana, Wyoming, North and South Dakota, and Minnesota, Cretaceous strata are preserved in the asymmetric Western Interior foreland basin. More than 5,200 m (17,000 ft) of Cretaceous strata are present in southwestern Montana, less than 300 m (1,000 ft) in eastern South Dakota. The asymmetry resulted from varying rates of subsidence due to tectonic and sediment loading. The strata consist primarily of sandstone, siltstone, mudstone, and shale. Conglomerate is locally abundant along the western margin, whereas carbonate is present in most areas of the eastern shelf. Sediment was deposited in both marine and nonmarine environments as the shoreline fluctuated during major tectonic and eustatic cycles.A discussion of Cretaceous strata from southwestern to east-central Montana, the Black Hills, eastern South Dakota, and southwestern Minnesota shows regional stratigraphy and facies relations, sequence, boundaries, and biostratigraphic and radiometric correlations. The thick Cretaceous strata in southwestern Montana typify nonmarine facies of the rapidly subsiding westernmost part of the basin. These strata include more than 3,000 m (10,000 ft) of synorogenic conglomerate of the Upper Cretaceous part of the Beaverhead Group. West of the Madison Range, sequence boundaries bracket the Kootenai (Aptian and Albian), the Blackleaf (Albian and Cenomanian), and the Frontier Formations (Cenomanian and Turonian); sequence boundaries are difficult to recognize because the rocks are dominantly non-marine. Cretaceous strata in east-central Montana (about 1,371 m; 4,500 ft thick) lie at the approximate depositional axis of the basin and are mostly marine terrigenous rocks. Chert-pebble zones in these rocks reflect stratigraphic breaks that may correlate with sequence boundaries to the east and west. Cretaceous rocks of the Black Hills region consist of a predominantly marine clastic sequence averaging approximately 1,524 m (5,000 ft) thick. The Cretaceous System in eastern South Dakota (457 to 610 m; 1,500 to 2,000 ft thick) consists of a marine shelf sequence dominated by shale and limestone. Major sequence boundaries in South Dakota are at the base of the Lower Cretaceous Lakota Formation, Fall River Sandstone, and Muddy Sandstone, and bracket the Upper Cretaceous Niobrara Formation.

Evaluating the Intersections of Socioeconomic Status and Health Impacts from Exposure to Air Pollution in Bogotá, Colombia

NASA Astrophysics Data System (ADS)

Baublitz, C. B.; Henderson, B. H.; Pachon, J. E.; Galvis, B. R.

2014-12-01

Colombia has strict economic divisions, which may be represented by six strata assigned by the National Planning Department. These are assigned by housing conditions and are arranged such that the divisions with subpar living conditions (strata levels one through three) may receive support from those with better than acceptable living conditions (strata levels five and six). Notably, division three no longer receives aid, and division four neither contributes to this system nor receives support. About ten percent of the population is in the upper three strata, while the remaining populace experiences subpar living conditions. Bogotá, DC has poor air quality that sometimes puts sensitive populations at risk due to particulate matter (PM). The local environmental agency has developed seven strategies to reduce air pollution, predominantly by regulating fixed and mobile sources, for the promotion of public health. Preliminary mapping of results indicates there may be higher concentrations of pollutants in areas whose residents are of a lower socioeconomic status (SES). Because it's more difficult for impoverished people to miss work or afford healthcare, higher exposure could have more significance for the city's overall health burden. The aim of this project is to determine the effective impactful regulatory strategy for the benefit of public health as a result of emission reductions. This will be done by using CMAQ results and BenMAP with information for long-term relative risk estimates for PM to find premature mortality rates per source type and location, segregated by strata division. A statistical regression will define the correspondence between health impact and SES. The benefit per reduction will be given in premature mortalities avoided per ton of PM emissions reduced per source type. For each of seven proposed regulatory strategies, this project provides results in mortalities avoided per ton of emissions of PM reduced per source type. It also compares these results against the strata divisions to analyze the correspondence between SES and exposure to air pollution. Because there are many industrial facilities close to residential areas of the lower three strata, it's predicted that fixed sources are the main contributor to health impacts for citizens of a lower SES.

Nonexplosive and explosive magma/wet-sediment interaction during emplacement of Eocene intrusions into Cretaceous to Eocene strata, Trans-Pecos igneous province, West Texas

USGS Publications Warehouse

Befus, K.S.; Hanson, R.E.; Miggins, D.P.; Breyer, J.A.; Busbey, A.B.

2009-01-01

Eocene intrusion of alkaline basaltic to trachyandesitic magmas into unlithified, Upper Cretaceous (Maastrichtian) to Eocene fluvial strata in part of the Trans-Pecos igneous province in West Texas produced an array of features recording both nonexplosive and explosive magma/wet-sediment interaction. Intrusive complexes with 40Ar/39Ar dates of ~ 47-46??Ma consist of coherent basalt, peperite, and disrupted sediment. Two of the complexes cutting Cretaceous strata contain masses of conglomerate derived from Eocene fluvial deposits that, at the onset of intrusive activity, would have been > 400-500??m above the present level of exposure. These intrusive complexes are inferred to be remnants of diatremes that fed maar volcanoes during an early stage of magmatism in this part of the Trans-Pecos province. Disrupted Cretaceous strata along diatreme margins record collapse of conduit walls during and after subsurface phreatomagmatic explosions. Eocene conglomerate slumped downward from higher levels during vent excavation. Coherent to pillowed basaltic intrusions emplaced at the close of explosive activity formed peperite within the conglomerate, within disrupted Cretaceous strata in the conduit walls, and within inferred remnants of the phreatomagmatic slurry that filled the vents during explosive volcanism. A younger series of intrusions with 40Ar/39Ar dates of ~ 42??Ma underwent nonexplosive interaction with Upper Cretaceous to Paleocene mud and sand. Dikes and sills show fluidal, billowed, quenched margins against the host strata, recording development of surface instabilities between magma and groundwater-rich sediment. Accentuation of billowed margins resulted in propagation of intrusive pillows into the adjacent sediment. More intense disruption and mingling of quenched magma with sediment locally produced fluidal and blocky peperite, but sufficient volumes of pore fluid were not heated rapidly enough to generate phreatomagmatic explosions. This work suggests that Trans-Pecos Texas may be an important locale for the study of subvolcanic phreatomagmatic processes and associated phenomena. Eocene intrusions in the study area underwent complex interactions with wet sediment at shallow levels beneath the surface in strata as old as Maastrichtian, which must have remained unlithified and rich in pore water for ~ 20-25??Ma. ?? 2009 Elsevier B.V. All rights reserved.

Re–Os geochronology of the lacustrine Green River Formation: Insights into direct depositional dating of lacustrine successions, Re–Os systematics and paleocontinental weathering

USGS Publications Warehouse

Cumming, Vivien M.; Selby, David; Lillis, Paul G.

2012-01-01

Lacustrine sedimentary successions provide exceptionally high-resolution records of continental geological processes, responding to tectonic, climatic and magmatic influences. These successions are therefore essential for correlating geological and climatic phenomena across continents and furthermore the globe. Producing accurate geochronological frameworks within lacustrine strata is challenging because the stratigraphy is often bereft of biostratigraphy and directly dateable tuff horizons. The rhenium–osmium (Re–Os) geochronometer is a well-established tool for determining precise and accurate depositional ages of marine organic-rich rocks. Lake systems with stratified water columns are predisposed to the preservation of organic-rich rocks and thus should permit direct Re–Os geochronology of lacustrine strata. We present Re–Os systematics from one of the world's best documented lacustrine systems, the Eocene Green River Formation, providing accurate Re–Os depositional dates that are supported by Ar–Ar and U–Pb ages of intercalated tuff horizons. Precision of the Green River Formation Re–Os dates is controlled by the variation in initial 187Os/188Os and the range of 187Re/188Os ratios, as also documented in marine systems. Controls on uptake and fractionation of Re and Os are considered to relate mainly to depositional setting and the type of organic matter deposited, with the need to further understand the chelating precursors of Re and Os in organic matter highlighted. In addition to geochronology, the Re–Os data records the 187Os/188Os composition of lake water (1.41–1.54) at the time of deposition, giving an insight into continental runoff derived from weathering of the geological hinterland of the Green River Formation. Such insights enable us to evaluate fluctuations in continental climatic, tectonic and magmatic processes and provide the ability for chemostratigraphic correlation combined with direct depositional dates. Furthermore, initial 187Os/188Os values can be used as a diagnostic tool to distinguish between lacustrine and marine depositional settings when compared to known oceanic 187Os/188Os values.

30 CFR 57.3203 - Rock fixtures.

Code of Federal Regulations, 2011 CFR

2011-07-01

... the ground in an area with similar strata, opening dimensions and ground stresses in any mine; or (2... has similar strata, opening dimensions, and ground stresses as the area where the fixtures are..., and the last bolt installed in each work area during the shift shall be accurately determined...

30 CFR 57.3203 - Rock fixtures.

Code of Federal Regulations, 2010 CFR

2010-07-01

... the ground in an area with similar strata, opening dimensions and ground stresses in any mine; or (2... has similar strata, opening dimensions, and ground stresses as the area where the fixtures are..., and the last bolt installed in each work area during the shift shall be accurately determined...

HYDROLOGICALLY-BASED CLASSIFICATION AS A TOOL TO REDUCE BACKGROUND VARIATION IN LAND USE - OR NUTRIENT - RESPONSE RELATIONSHIPS IN LAKE MICHIGAN COASTAL RIVERINE WETLANDS

EPA Science Inventory

Flow-based watershed classes provide useful strata for sampling and assessment schemes both for instream condition and condition of downstream receiving waters, and may provide useful strata for development of nutrient criteria.

Petroleum geology of the mid-Atlantic continental margin, offshore Virginia

USGS Publications Warehouse

Bayer, K.C.; Milici, R.C.

1989-01-01

The Baltimore Canyon Trough, a major sedimentary basin on the Atlantic continental shelf, contains up to 18 km of Mesozoic and Cenozoic strata. The basin has been studied extensively by multichannel common depth point (CDP) seismic reflection profiles and has been tested by drilling for hydrocarbon resources in several places. The Mesozoic and Cenozoic strata contained in the basin were deposited in littoral to bathyal depositional settings and contain immature to marginally mature oil-prone and gas-prone kerogen. The more deeply buried strata of Early Mesozoic age are more likely to be thermally mature than are the younger strata with respect to hydrocarbon generation, but contain terrestrially derived coaly organic matter that would be prone to yield gas, rather than oil. An analysis of available CDP seismic reflection data has indicated that there are several potential hydrocarbon plays in the area offshore of Virginia. These include: (1) Lower Mesozoic synrift basins that appear similar to those exposed in the Appalachian Piedmont, (2) a stratigraphic updip pinchout of strata of Early Mesozoic age in the offshore region near the coast, (3) a deeply buried paleoshelf edge, where seismic reflectors dip sharply seaward; and (4) a Cretaceous/Jurassic shelf edge beneath the present continental rise. Of these, the synrift basins and Cretaceous/Jurassic shelf edge are considered to be the best targets for exploration. ?? 1989.

Implications of diapir-derived detritus and gypsic paleosols in Lower Triassic strata near the Castle Valley salt wall, Paradox Basin, Utah

NASA Astrophysics Data System (ADS)

Lawton, Timothy F.; Buck, Brenda J.

2006-10-01

Gypsum-bearing growth strata and sedimentary facies of the Moenkopi Formation on the crest and NE flank of the Castle Valley salt wall in the Paradox Basin record salt rise, evaporite exposure, and salt-withdrawal subsidence during the Early Triassic. Detrital gypsum and dolomite clasts derived from the middle Pennsylvanian Paradox Formation were deposited in strata within a few kilometers of the salt wall and indicate that salt rise rates roughly balanced sediment accumulation, resulting in long-term exposure of mobile evaporite. Deposition took place primarily in flood-basin or inland sabkha settings that alternated between shallow subaqueous and subaerial conditions in a hyperarid climate. Matrix-supported and clast-supported conglomerates with gypsum fragments represent debris-flow deposits and reworked debris-flow deposits, respectively, interbedded with flood-basin sandstone and siltstone during development of diapiric topography. Mudstone-rich flood-basin deposits with numerous stage I to III gypsic paleosols capped by eolian gypsum sand sheets accumulated during waning salt-withdrawal subsidence. Association of detrital gypsum, eolian gypsum, and gypsic paleosols suggests that the salt wall provided a common source for gypsum in the surrounding strata. This study documents a previously unrecognized salt weld with associated growth strata containing diapir-derived detritus and gypsic palesols that can be used to interpret halokinesis.

[Intersection between gender and socioeconomic status in medical sciences career choice].

PubMed

Gallardo-Hernández, Georgina; Ortiz-Hernández, Luis; Compeán-Dardón, Sandra; Verde-Flota, Elizabeth; Delgado-Sáncnchez, Guadalupe; Tamez-González, Silivia

2006-01-01

Analyze the relationship between gender identity and socioeconomic level associated with career choice among undergraduate students selecting the area of health sciences. Our sample was comprised of first year medical nutrition, dentistry and nursing students (n=637) admitted to the Universidad Autonoma Metropolitana - Xochimilco. A self administered questionnaire was used. The dependent variable was career choice. Independent variables included socioeconomic status, gender norms in student's homes, and gender stereotype internalization. More female nursing students came from low socioeconomic strata, while medical students had a higher socioeconomic status. Among males, more nursing and medical students belonged to a higher socioeconomicstrata. Nutrition and dentistry students belonged to a medium strata. In comparison with males from high socioeconomic strata more male participants reported that household chores were divided among men and women. For women, as the socioeconomic level increased, the participation of men and women also increased. In the indicators of internalization of gender stereotypes, nursing students had the highest rates in the submission scale, but the lowest for masculinity and machismo. As the socioeconomic strata increased, the characteristics of masculinity and machismo also increased. The present results seem to indicate that among women of low socioeconomic strata more traditional gender stereotypes prevail which lead them to seek career choices considered femenine. Among men, there is a clear relationship between career choice, socioeconomic level and internalization of gender stereotypes.

Derivation of S and Pb in phanerozoic intrusion-related metal deposits from neoproterozoic sedimentary pyrite, Great Basin, United States

USGS Publications Warehouse

Vikre, Peter G.; Poulson, S.R.; Koenig, Alan E.

2011-01-01

The thick (≤8 km), regionally extensive section of Neoproterozoic siliciclastic strata (terrigenous detrital succession, TDS) in the central and eastern Great Basin contains sedimentary pyrite characterized by mostly high δ34S values (−11.6 to 40.8‰, >70% exceed 10‰; 51 analyses) derived from reduction of seawater sulfate, and by markedly radiogenic Pb isotopes (207Pb/204Pb >19.2; 15 analyses) acquired from clastic detritus eroded from Precambrian cratonal rocks to the east-southeast. In the overlying Paleozoic section, Pb-Zn-Cu-Ag-Au deposits associated with Jurassic, Cretaceous, and Tertiary granitic intrusions (intrusion-related metal deposits) contain galena and other sulfide minerals with S and Pb isotope compositions similar to those of TDS sedimentary pyrite, consistent with derivation of deposit S and Pb from TDS pyrite. Minor element abundances in TDS pyrite (e.g., Pb, Zn, Cu, Ag, and Au) compared to sedimentary and hydrothermal pyrite elsewhere are not noticeably elevated, implying that enrichment in source minerals is not a precondition for intrusion-related metal deposits.Three mechanisms for transferring components of TDS sedimentary pyrite to intrusion-related metal deposits are qualitatively evaluated. One mechanism involves (1) decomposition of TDS pyrite in thermal aureoles of intruding magmas, and (2) aqueous transport and precipitation in thermal or fluid mixing gradients of isotopically heavy S, radiogenic Pb, and possibly other sedimentary pyrite and detrital mineral components, as sulfide minerals in intrusion-related metal deposits. A second mechanism invokes mixing and S isotope exchange in thermal aureoles of Pb and S exsolved from magma and derived from decomposition of sedimentary pyrite. A third mechanism entails melting of TDS strata or assimilation of TDS strata by crustal or mantle magmas. TDS-derived or assimilated magmas ascend, decompress, and exsolve a mixture of TDS volatiles, including isotopically heavy S and radiogenic Pb from sedimentary pyrite, and volatiles acquired from deeper crustal or mantle sources.In the central and eastern Great Basin, the wide distribution and high density of small to mid-sized vein, replacement, and skarn intrusion-related metal deposits in lower Paleozoic rocks that contain TDS sedimentary pyrite S and Pb reflect (1) prolific Jurassic, Cretaceous, and Tertiary magmatism, (2) a regional, substrate reservoir of S and Pb in permeable and homogeneous siliciclastic strata, and (3) relatively small scale concentration of substrate and magmatic components. Large intrusion-related metal deposits in the central and eastern Great Basin acquired S and most Pb from thicker lithospheric sections.

Identification of the Paleocene-Eocene boundary in coastal strata in the Otway Basin, Victoria, Australia

NASA Astrophysics Data System (ADS)

Frieling, Joost; Huurdeman, Emiel P.; Rem, Charlotte C. M.; Donders, Timme H.; Pross, Jörg; Bohaty, Steven M.; Holdgate, Guy R.; Gallagher, Stephen J.; McGowran, Brian; Bijl, Peter K.

2018-02-01

Detailed, stratigraphically well-constrained environmental reconstructions are available for Paleocene and Eocene strata at a range of sites in the southwest Pacific Ocean (New Zealand and East Tasman Plateau; ETP) and Integrated Ocean Discovery Program (IODP) Site U1356 in the south of the Australo-Antarctic Gulf (AAG). These reconstructions have revealed a large discrepancy between temperature proxy data and climate models in this region, suggesting a crucial error in model, proxy data or both. To resolve the origin of this discrepancy, detailed reconstructions are needed from both sides of the Tasmanian Gateway. Paleocene-Eocene sedimentary archives from the west of the Tasmanian Gateway have unfortunately remained scarce (only IODP Site U1356), and no well-dated successions are available for the northern sector of the AAG. Here we present new stratigraphic data for upper Paleocene and lower Eocene strata from the Otway Basin, southeast Australia, on the (north)west side of the Tasmanian Gateway. We analyzed sediments recovered from exploration drilling (Latrobe-1 drill core) and outcrop sampling (Point Margaret) and performed high-resolution carbon isotope geochemistry of bulk organic matter and dinoflagellate cyst (dinocyst) and pollen biostratigraphy on sediments from the regional lithostratigraphic units, including the Pebble Point Formation, Pember Mudstone and Dilwyn Formation. Pollen and dinocyst assemblages are assigned to previously established Australian pollen and dinocyst zonations and tied to available zonations for the SW Pacific. Based on our dinocyst stratigraphy and previously published planktic foraminifer biostratigraphy, the Pebble Point Formation at Point Margaret is dated to the latest Paleocene. The globally synchronous negative carbon isotope excursion that marks the Paleocene-Eocene boundary is identified within the top part of the Pember Mudstone in the Latrobe-1 borehole and at Point Margaret. However, the high abundances of the dinocyst Apectodinium prior to this negative carbon isotope excursion prohibit a direct correlation of this regional bio-event with the quasi-global Apectodinium acme at the Paleocene-Eocene Thermal Maximum (PETM; 56 Ma). Therefore, the first occurrence of the pollen species Spinizonocolpites prominatus and the dinocyst species Florentinia reichartii are here designated as regional markers for the PETM. In the Latrobe-1 drill core, dinocyst biostratigraphy further indicates that the early Eocene ( ˜ 56-51 Ma) sediments are truncated by a ˜ 10 Myr long hiatus overlain by middle Eocene ( ˜ 40 Ma) strata. These sedimentary archives from southeast Australia may prove key in resolving the model-data discrepancy in this region, and the new stratigraphic data presented here allow for detailed comparisons between paleoclimate records on both sides of the Tasmanian Gateway.

Preliminary Geologic Map of the White Sulphur Springs 30' x 60' Quadrangle, Montana

USGS Publications Warehouse

Reynolds, Mitchell W.; Brandt, Theodore R.

2006-01-01

The geologic map of the White Sulphur Springs quadrangle, scale 1:100,000, was made as part of the Montana Investigations Project to provide new information on the stratigraphy, structure, and geologic history of the geologically complex area in west-central Montana. The quadrangle encompasses about 4,235 km2 (1,635 mi2), across part of the Smith River basin, the west end of the Little Belt Mountains, the Castle Mountains, and the upper parts of the basins of the North Forks of the Smith and Musselshell Rivers and the Judith River. Geologically the quadrangle extends across the eastern part of the Helena structural salient in the Rocky Mountain thrust belt, a segment of the Lewis and Clark tectonic zone, west end of the ancestral central Montana uplift, and the southwest edge of the Judith basin. Rocks and sediments in the White Sulphur Springs quadrangle are assigned to 88 map units on the basis of rock or sediment type and age. The oldest rock exposed is Neoarchean diorite that is infolded with Paleoproterozoic metamorphic rocks including gneiss, diorite, granite, amphibolite, schist, and mixed metamorphic rock types. A thick succession of the Mesoproterozoic Belt Supergroup unconformably overlies the metamorphic rocks and, in turn, is overlain unconformably by Phanerozoic sedimentary and volcanic rocks. Across most of the quadrangle, the pre-Tertiary stratigraphic succession is intruded by Eocene dikes, sills, and plutons. The central part of the Little Belt Mountains is generally underlain by laccoliths and sheet-like bodies of quartz monzonite or dacite. Oligocene andesitic basalt flows in the western and southern part of the quadrangle document both the configuration of the late Eocene erosional surfaces and the extent of extensional faulting younger than early Oligocene in the area. Pliocene, Miocene, and Oligocene strata, mapped as 11 units, consist generally of interbedded sand, gravel, and tuffaceous sedimentary rock. Quaternary and Quaternary-Tertiary sediments rest across the older Cenozoic deposits and across all older rocks. The Quaternary and Quaternary-Tertiary deposits generally are gravels that mantle broad erosional surfaces on the flanks of the mountains, gravels in stream channels, and colluvium and landslide deposits on hill sides. Glacial deposits, representing at least two stages of glaciation, are present in the northern part of the Little Belt Mountains. The geologic structure of much of the northwest part of the quadrangle is a broad uplift, in the core of which the Paleoproterozoic and Neoarchean metamorphic rocks are exposed. Down plunge to the east, the succession of Phanerozoic sedimentary rocks define an east-trending arch, cored locally by Mesoproterozoic strata of the Belt Supergroup. The north flank of the arch dips steeply north as a monocline. Stratigraphic relations among Mississippian, Pennsylvanian, and Jurassic strata document the recurrent uplift and erosion on that north flank. The broader arch of the Little Belt Mountains reflects the west plunge of the ancestral Central Montana uplift. The eastern extension of the Lewis and Clark tectonic zone is exposed in the southern half of the quadrangle where the Volcano Valley fault zone curves from west to southeast as a reverse fault along which the latest movement is up on the south side. The fault zone ends in an anticline in the south-central margin of the quadrangle. Stratigraphic overlap of Phanerozoic strata over the truncated edges of Mesoproterozoic units documents that the area of the eastern terminus of the fault zone was tectonically recurrently active. Northeast trending strike-slip faults displace Mesoproterozoic rocks in the northwest and south-central parts of the quadrangle. Several of those faults are overlain unconformably by the Middle Cambrian Flathead Sandstone. Other north-east and west-trending faults across the central part of the quadrangle are intruded by middle Eocene plutons. You

Age Differences and Dimensions of Religious Behavior

ERIC Educational Resources Information Center

Johnson, Arthur L.; And Others

1974-01-01

This research explores the magnitude, sources, and consequences of differences among age strata in various dimensions of religious orientation and practice. Analysis of a national sample of 4444 Lutheran church members, ages 16-65, revealed patterns of age strata differences that supported a "selective gap" theory rather than a "great gap"…

Very low-grade metamorphic rocks in some representative districts in Tibet

NASA Astrophysics Data System (ADS)

Bi, X.; Mo, X.

2011-12-01

*Response author: Bi,Xianmei,bixm10@sina.com Very low grade metamorphic rocks are widely distributed in Tibet, providing an insight into deformation and metamorphism during the evolution of the Tibetan Plateau. Eighty five Samples of clay mineral-bearing rocks has been collected from various strata including D, P1, T1, T2, T3, J1, J3, K1, K2 and N strata in the Qiangtang terrane, the Gangdese, the Yarlung Zangbo suture and the Tethyan Himalaya. Analyses and refining of clay minerals in samples have been conducted in the Laboratory of X-ray Diffraction, Institute of Petroleum Exploration. Index of illite crystallinity (Ic) along with average thickness of crystal layers of illite, reflectivity of vitrinite and of clay mineral association have been employed as indicators of degree of very low-grade metamorphism. The scheme of classification[1,2] of very-low grade metamorphism based on clay mineral indexes ( mainly index of illite crystallinity) has been used in the present work, that is, low metamorphism (Ic<0.25), higher very-low grade metamorphism (Ic = 0.25-0.30), lower very-low grade metamorphism (Ic = 0.30-0.42) and diagenesis (Ic>0.42). The analytical results show interesting information. In the Qiangtang terrane, clay minerals in the Jurassic strata have indexes of illite crystalinity (Ic) 0.47-0.70, indicating higher diagenesis and in favor of petroleum-generation. However, index of illite crystalinity (Ic) for the Devonian is 0.23, indicating low metamorphism. Indexes of illite crystalinity (Ic) for the J-K strata in middle Gangdese are mostly 0.37-0.25 (very-low grade metamorphism) and a few 0.78-0.48 (diagenesis). Indexes of illite crystalinity (Ic) for the C-P strata in eastern Gangdese are mostly 0.25-0.42 (very-low grade metamorphism) and a few 0.20-0.25 (low metamorphism). The Mesozoic and Cenozoic magmatism and related mineralization are very strong in the Gangdese, which may affect in some extent on indexes of illite crystalinity. In Tethyan Himalaya, clay mineral-bearing rocks from P1, T1, T2, T3, J1 and J3 strata underwent low-very low grade metamorphism, having indexes of illite crystalinity (Ic) 0.12 for P1 stratum, 0.21 for T1 stratum and 0.22-0.33 for the strata from T2 to J3, whereas K1 and N strata underwent diagenesis, having Ic = 0.52 and 1.61, respectively. Metamorphic degree generally reduced from older strata to younger strata according to clay mineral indexes. The rocks affected by magmatism or by major faulting, however, were out of the general trend and increased their metamorphic degree by 0.1-0.3 units reduction of index of illite crystallinity. Rocks within Yarlung Zangbo suture show higher metamorphic degree than those in Tethyan Himalaya. For instance, while the late Triassic has 0.19 of index of illite crystallinity in the former (the Yarlung Zangbo suture), 0.27-0.33 of indexes of illite crystallinity in the latter. The early Cretaceous has 0.28 of index of illite crystallinity in the former, whereas 0.52 in the latter. However, the late Cretaceous Xigaze Group formed in a fore-arc environment was weakly metamorphosed, having Ic 0.7-1.6 and all falling into diagenesis field.

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

Nyagah, K.; Cloeter, J.J.; Maende, A.

The Lamu basin occupies the coastal onshore and offshore areas of south-east Kenya. This fault bounded basin formed as a result of the Paleozoic-early Mesozoic phase of rifting that developed at the onset of Gondwana dismemberment. The resultant graben was filled by Karroo (Permian-Early Jurassic) continental siliciclastic sediments. Carbonate deposits associated with the Tethyan sea invasion, dominate the Middle to Late Jurassic basin fill. Cessation of the relative motion between Madagascar and Africa in the Early Cretaceous, heralded passive margin development and deltaic sediment progradation until the Paleogene. Shallow seas transgressed the basin in the Miocene when another carbonate regimemore » prevailed. The basin depositional history is characterized by pulses of transgressive and regressive cycles, bounded by tectonically enhanced unconformities dividing the total sedimentary succession into discrete megasequences. Source rock strata occur within Megasequence III (Paleogene) depositional cycle and were lowered into the oil window in Miocene time, when the coastal parts of the basin experienced the greatest amount of subsidence. The tectono-eustatic pulses of the Tertiary brought about source and reservoir strata into a spatial relationship in which hydrocarbons could be entrapped. A basement high on the continental shelf has potential for Karroo sandstone and Jurassic limestone reservoirs. Halokinesis of Middle Jurassic salt in Miocene time provides additional prospects in the offshore area. Paleogene deltaic sands occur in rotated listric fault blacks. A Miocene reef Play coincides with an Eocene source rock kitchen.« less

Stand, species, and individual traits impact transpiration in historically disturbed forests.

NASA Astrophysics Data System (ADS)

Blakely, B.; Rocha, A. V.; McLachlan, J. S.

2017-12-01

Historic logging disturbances have changed the structure and species composition of most Northern temperate forests. These changes impact the process of transpiration - which in turn impacts canopy surface temperature - but the links among structure, composition, and transpiration remain unclear. For this reason, ecosystem models typically use simplified structure and composition to simulate the impact of disturbances on forest transpiration. However, such simplifications ignore real variability among stands, species, and individual trees that may strongly influence transpiration across spatial and temporal scales. To capture this variability, we monitored transpiration in 48 individual trees of multiple species in both undisturbed (400+ yr) and historically logged (80 - 120 yr) forests. Using modern and historic forest surveys, we upscaled our observations to stand and regional scales to identify the key changes impacting transpiration. We extended these inferences by establishing a relationship between transpiration and measured surface temperature, linking disturbance-induced changes in structure and composition to local and regional climate. Despite greater potential evapotranspiration and basal area, undisturbed forest transpired less than disturbed (logged) forest. Transpiration was a strong predictor of surface temperature, and the canopy surface was warmer in undisturbed forest. Transpiration differences among disturbed and undisturbed forests resulted from (1) lesser transpiration and dampened seasonality in evergreen species (2) greater transpiration in younger individuals within a species, and (3) strong transpiration by large individuals. When transpiration was scaled to the stand or regional level in a simplified manner (e.g. a single transpiration rate for all deciduous individuals), the resulting estimates differed markedly from the original. Stand- species- and individual-level traits are therefore essential for understanding how transpiration and surface temperature respond to disturbance. Without consideration of such traits, current ecosystem models may struggle to capture the true impact of logging disturbances on forest transpiration.

Effect of rhizobacterial consortia from undisturbed arid- and agro-ecosystems on wheat growth under different conditions.

PubMed

Inostroza, N G; Barra, P J; Wick, L Y; Mora, M L; Jorquera, M A

2017-02-01

Plant growth-promoting rhizobacteria (PGPR) are studied as complements/alternatives to chemical fertilizers used in agriculture. However, poor information exists on the potential of PGPR from undisturbed ecosystems. Here, we have evaluated the plant growth-promoting (PGP) effect of rhizobacterial consortia from undisturbed Chilean arid ecosystems (Consortium C1) and agro-ecosystems (Consortium C2) on plant biomass production. The PGP effects of C1 and C2 were assayed in wheat seedlings (Triticum aestivum L.) grown in pots under growth chamber conditions and in pots placed in an open greenhouse under natural conditions, using two different Chilean Andisols (Piedras Negras and Freire series) kept either at 30 or 60% of their maximum water holding capacity (MWHC). PGP effects depended on the soil type, MWHC and the growth conditions tested. Although both consortia showed PGB effects in artificial soils relative to controls in growth chambers, only C1 provoked a PGP effect at 60% MWHC in phosphorus-poor soil of the 'Piedras Negras' series. At natural conditions, however, only C1 exhibited statistically significant PGP effects at 30% MWHC in 'Piedras Negras', yet and most importantly allowed to maintain similar plant biomass as at 60% MWHC. Our results support possible applications of rhizobacterial consortia from arid ecosystems to improve wheat growth in Chilean Andisols under water shortage conditions. Wheat seedling inoculated with rhizobacterial consortia obtained from an undisturbed Chilean arid ecosystem showed improved growth in phosphorus-poor and partly dry soil. Arid ecosystems should be considered in further studies as an alternative source of microbial inoculants for agro-ecosystems subjected to stressful conditions by low nutrients and/or adverse climate events. © 2016 The Society for Applied Microbiology.

Tree seedlings respond to both light and soil nutrients in a Patagonian evergreen-deciduous forest.

PubMed

Promis, Alvaro; Allen, Robert B

2017-01-01

Seedlings of co-occurring species vary in their response to resource availability and this has implications for the conservation and management of forests. Differential shade-tolerance is thought to influence seedling performance in mixed Nothofagus betuloides-Nothofagus pumilio forests of Patagonia. However, these species also vary in their soil nutrient requirements. To determine the effects of light and soil nutrient resources on small seedlings we examined responses to an experimental reduction in canopy tree root competition through root trenching and restricting soil nutrient depletion through the addition of fertilizer. To understand the effect of light these treatments were undertaken in small canopy gaps and nearby beneath undisturbed canopy with lower light levels. Seedling diameter growth was greater for N. pumilio and height growth was greater for N. betuloides. Overall, diameter and height growth were greater in canopy gaps than beneath undisturbed canopy. Such growths were also greater with fertilizer and root trenching treatments, even beneath undisturbed canopy. Seedling survival was lower under such treatments, potentially reflecting thinning facilitated by resource induced growth. Finally, above-ground biomass did not vary among species although the less shade tolerant N. pumilio had higher below-ground biomass and root to shoot biomass ratio than the more shade tolerant N. betuloides. Above- and below-ground biomass were higher in canopy gaps so that the root to shoot biomass ratio was similar to that beneath undisturbed canopy. Above-ground biomass was also higher with fertilizer and root trenching treatments and that lowered the root to shoot biomass ratio. Restricting soil nutrient depletion allowed seedlings of both species to focus their responses above-ground. Our results support a view that soil nutrient resources, as well as the more commonly studied light resources, are important to seedlings of Nothofagus species occurring on infertile soils.

Sediment Transport and Dust Flux in Disturbed and Undisturbed Dryland Ecosystems: From Site Specific Estimates to Trends Across Gradients of Woody Plant Cover

NASA Astrophysics Data System (ADS)

Field, J. P.; Breshears, D. D.; Whicker, J. J.; Zou, C. B.; Allen, C. D.

2007-12-01

Aeolian sediment transport and associated dust flux are important processes in dryland ecosystems where vegetation cover is inherently sparse relative to more mesic ecosystems. Aeolian processes in dryland ecosystems are strongly influenced by the spatial density of roughness elements, which is largely determined by woody plant height and spacing. Despite the global extent of dryland ecosystems, relatively few measurements of aeolian sediment transport have been made within these systems, and these few existing measurements have not been systematically evaluated with respect to gradients of woody plant cover. We report measured aeolian sediment transport in an undisturbed and disturbed semiarid grasslands in southern Arizona. To place our estimate in a broader context, we compared our site-specific findings to other recently published measurements of aeolian sediment transport in disturbed and undisturbed dryland ecosystems. We propose a new conceptual framework for dryland aeolian sediment transport and dust flux as a function of woody plant cover that integrates our site-specific data with the broader literature base. Our findings suggest that for relatively undisturbed ecosystems, shrublands have inherently greater aeolian sediment transport and associated dust flux than grasslands, woodlands and forests due to wake interference flow associated with the height and spacing of woody roughness elements. Furthermore, the proposed framework suggests that for disturbed ecosystems, the upper bound for aeolian sediment transport increases as a function of decreasing woody plant cover. As a result, aeolian sediment transport spans a relatively small range in woodlands and forests, an intermediate range in shrublands, and the largest range in grasslands. Our framework is applicable both within locations and across broad gradients

Postimpact deformation associated with the late Eocene Chesapeake Bay impact structure in southeastern Virginia

USGS Publications Warehouse

Johnson, G.H.; Kruse, S.E.; Vaughn, A.W.; Lucey, J.K.; Hobbs, C. H.; Powars, D.S.

1998-01-01

Upper Cenozoic strata covering the Chesapeake Bay impact structure in southeastern Virginia record intermittent differential movement around its buried rim. Miocene strata in a graben detected by seismic surveys on the York River exhibit variable thickness and are deformed above the creater rim. Fan-like interformational and intraformational angular unconformities within Pliocene-Pleistocene strata, which strike parallel to the crater rim and dip 2-3?? away from the crater center, indicate that deformation and deposition were synchronous. Concentric, large-scale crossbedded, bioclastics and bodies of Pliocene age within ~20km of the buried crater rim formed on offshore shoals, presumably as subsiding listric slump blocks rotated near the crater rim.

Computer Literacy and Social Stratification. Interactive Technology Laboratory Report #9.

ERIC Educational Resources Information Center

Mehan, Hugh

As schools acquire and use computers for educational purposes, two major questions arise: (1) whether students from different strata of society will obtain equal access to computers, and (2) whether students from different strata of society will be taught similar or different uses of the computer. To explore the relationship between the…

76 FR 69295 - Strata Energy, Inc.; Establishment of Atomic Safety and Licensing Board

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-08

...: Strata Energy, Inc. (Ross In Situ Recovery Uranium Project) This proceeding involves a license... byproduct materials license at its Ross In Situ Recovery Uranium Project site located in Crook County... dated December 29, 1972, published in the Federal Register, 37 FR 28,710 (1972), and the Commission's...

Characteristics of the Russian Lower Class

ERIC Educational Resources Information Center

Tikhonova, N. E.

2011-01-01

Lower socioeconomic strata in Russia have their origins in both the former Soviet lower strata and economic decline of the 1990s. Part of the reason for their persistence is the geographic mismatch between jobs and the labor supply, in addition to lack of education, skills, and social support. The situation cannot be solved by just providing…

The ultrastructure of subgingival dental plaque, revealed by high-resolution field emission scanning electron microscopy.

PubMed

Holliday, Richard; Preshaw, Philip M; Bowen, Leon; Jakubovics, Nicholas S

2015-01-01

To explore the ultrastructure of subgingival dental plaque using high-resolution field emission scanning electron microscopy (FE-SEM) and to investigate whether extracellular DNA (eDNA) could be visualised in ex vivo samples. Ten patients were recruited who fulfilled the inclusion criteria (teeth requiring extraction with radiographic horizontal bone loss of over 50% and grade II/III mobility). In total, 12 teeth were extracted using a minimally traumatic technique. Roots were sectioned using a dental air turbine handpiece, under water cooling to produce 21 samples. Standard fixation and dehydration protocols were followed. For some samples, gold-labelled anti-DNA antibodies were applied before visualising biofilms by FE-SEM. High-resolution FE-SEMs of subgingival biofilm were obtained in 90% of the samples. The sectioning technique left dental plaque biofilms undisturbed. Copious amounts of extracellular material were observed in the plaque, which may have been eDNA as they had a similar appearance to labelled eDNA from in vitro studies. There was also evidence of membrane vesicles and open-ended tubular structures. Efforts to label eDNA with immune-gold antibodies were unsuccessful and eDNA was not clearly labelled. High-resolution FE-SEM images were obtained of undisturbed subgingival ex vivo dental plaque biofilms. Important structural features were observed including extracellular polymeric material, vesicles and unusual open tubule structures that may be remnants of lysed cells. The application of an eDNA immune-gold-labelling technique, previously used successfully in in vitro samples, did not clearly identify eDNA in ex vivo samples. Further studies are needed to characterise the molecular composition of the observed extracellular matrix material.

The ultrastructure of subgingival dental plaque, revealed by high-resolution field emission scanning electron microscopy

PubMed Central

Holliday, Richard; Preshaw, Philip M; Bowen, Leon; Jakubovics, Nicholas S

2015-01-01

Objectives/Aims: To explore the ultrastructure of subgingival dental plaque using high-resolution field emission scanning electron microscopy (FE-SEM) and to investigate whether extracellular DNA (eDNA) could be visualised in ex vivo samples. Materials and Methods: Ten patients were recruited who fulfilled the inclusion criteria (teeth requiring extraction with radiographic horizontal bone loss of over 50% and grade II/III mobility). In total, 12 teeth were extracted using a minimally traumatic technique. Roots were sectioned using a dental air turbine handpiece, under water cooling to produce 21 samples. Standard fixation and dehydration protocols were followed. For some samples, gold-labelled anti-DNA antibodies were applied before visualising biofilms by FE-SEM. Results: High-resolution FE-SEMs of subgingival biofilm were obtained in 90% of the samples. The sectioning technique left dental plaque biofilms undisturbed. Copious amounts of extracellular material were observed in the plaque, which may have been eDNA as they had a similar appearance to labelled eDNA from in vitro studies. There was also evidence of membrane vesicles and open-ended tubular structures. Efforts to label eDNA with immune-gold antibodies were unsuccessful and eDNA was not clearly labelled. Conclusions: High-resolution FE-SEM images were obtained of undisturbed subgingival ex vivo dental plaque biofilms. Important structural features were observed including extracellular polymeric material, vesicles and unusual open tubule structures that may be remnants of lysed cells. The application of an eDNA immune-gold-labelling technique, previously used successfully in in vitro samples, did not clearly identify eDNA in ex vivo samples. Further studies are needed to characterise the molecular composition of the observed extracellular matrix material. PMID:29607057

Nesting ecology of a population of Gopherus agassizii at a utility-scale wind energy facility in southern California

USGS Publications Warehouse

Ennen, Joshua R.; Lovich, Jeffrey E.; Meyer, Katherin P.; Bjurlin, Curtis; Arundel, Terence R.

2012-01-01

We investigated the annual nesting ecology of a population of Desert Tortoises (Gopherus agassizii) inhabiting a utility-scale renewable energy (USRE) facility in southern California and compared our results with populations inhabiting relatively undisturbed sites. In 2000, 15 radio-tracked females produced 29 clutches, and 24 nests were monitored to examine nest-site selection, nest predation, hatching success, date of emergence of hatchlings, and hatchling mass and carapace length. Overall, the nesting ecology of the population inhabiting the USRE facility was very similar to other populations of Desert Tortoises inhabiting relatively undisturbed habitats. Oviposition occurred from 12 May to 8 July, which was similar to other sites. Nest depths (11.1 cm), nest predation (12%), hatchling emergence date (7 August and 29 September), and hatchling morphometrics (i.e., MCL: 44.5 mm; mass: 23 g) were all within ranges reported in other populations. Unlike within other populations, we observed no relationship between hatchling size and either maternal body size or egg width. We found no evidence of females selecting for a particular burrow for oviposition of eggs based on environmental or anthropogenic variables. Most nests were located in or near burrows, and nest depth was greater for nests near the entrance than those deeper in the burrow. Although this study suggests that the nesting ecology of the Desert Tortoise population we studied was not adversely affected by the USRE facility, this relationship is only correlative because our study was not a before-after-control-impact (BACI) study, which would establish a cause and effect relationship. As pointed out in a recent review, BACI studies are critically needed to address the wildlife impacts of utility-scale renewable energy development.

Identification of coal seam strata from geophysical logs of borehole using Adaptive Neuro-Fuzzy Inference System

NASA Astrophysics Data System (ADS)

Yegireddi, Satyanarayana; Uday Bhaskar, G.

2009-01-01

Different parameters obtained through well-logging geophysical sensors such as SP, resistivity, gamma-gamma, neutron, natural gamma and acoustic, help in identification of strata and estimation of the physical, electrical and acoustical properties of the subsurface lithology. Strong and conspicuous changes in some of the log parameters associated with any particular stratigraphy formation, are function of its composition, physical properties and help in classification. However some substrata show moderate values in respective log parameters and make difficult to identify or assess the type of strata, if we go by the standard variability ranges of any log parameters and visual inspection. The complexity increases further with more number of sensors involved. An attempt is made to identify the type of stratigraphy from borehole geophysical log data using a combined approach of neural networks and fuzzy logic, known as Adaptive Neuro-Fuzzy Inference System. A model is built based on a few data sets (geophysical logs) of known stratigraphy of in coal areas of Kothagudem, Godavari basin and further the network model is used as test model to infer the lithology of a borehole from their geophysical logs, not used in simulation. The results are very encouraging and the model is able to decipher even thin cola seams and other strata from borehole geophysical logs. The model can be further modified to assess the physical properties of the strata, if the corresponding ground truth is made available for simulation.

Spatial Probability Distribution of Strata's Lithofacies and its Impacts on Land Subsidence in Huairou Emergency Water Resources Region of Beijing

NASA Astrophysics Data System (ADS)

Li, Y.; Gong, H.; Zhu, L.; Guo, L.; Gao, M.; Zhou, C.

2016-12-01

Continuous over-exploitation of groundwater causes dramatic drawdown, and leads to regional land subsidence in the Huairou Emergency Water Resources region, which is located in the up-middle part of the Chaobai river basin of Beijing. Owing to the spatial heterogeneity of strata's lithofacies of the alluvial fan, ground deformation has no significant positive correlation with groundwater drawdown, and one of the challenges ahead is to quantify the spatial distribution of strata's lithofacies. The transition probability geostatistics approach provides potential for characterizing the distribution of heterogeneous lithofacies in the subsurface. Combined the thickness of clay layer extracted from the simulation, with deformation field acquired from PS-InSAR technology, the influence of strata's lithofacies on land subsidence can be analyzed quantitatively. The strata's lithofacies derived from borehole data were generalized into four categories and their probability distribution in the observe space was mined by using the transition probability geostatistics, of which clay was the predominant compressible material. Geologically plausible realizations of lithofacies distribution were produced, accounting for complex heterogeneity in alluvial plain. At a particular probability level of more than 40 percent, the volume of clay defined was 55 percent of the total volume of strata's lithofacies. This level, equaling nearly the volume of compressible clay derived from the geostatistics, was thus chosen to represent the boundary between compressible and uncompressible material. The method incorporates statistical geological information, such as distribution proportions, average lengths and juxtaposition tendencies of geological types, mainly derived from borehole data and expert knowledge, into the Markov chain model of transition probability. Some similarities of patterns were indicated between the spatial distribution of deformation field and clay layer. In the area with roughly similar water table decline, locations in the subsurface having a higher probability for the existence of compressible material occur more than that in the location with a lower probability. Such estimate of spatial probability distribution is useful to analyze the uncertainty of land subsidence.

Proposed Auxiliary Boundary Stratigraphic Section and Point (ASSP) for the base of the Ordovician System at Lawson Cove, Utah, USA

USGS Publications Warehouse

Miller, James F.; Evans, Kevin R.; Ethington, Raymond L.; Freeman, Rebecca; Loch, James D.; Repetski, John E.; Ripperdan, Robert; Taylor, John F.

2016-01-01

The Global boundary Stratotype Section and Point (GSSP) for the base of the Ordovician System is at the First Appearance Datum (FAD) of the conodont Iapetognathus fluctivagus at Green Point in Newfoundland, Canada. Strata there are typical graptolitic facies that were deposited near the base of the continental slope.We propose establishing an Auxiliary boundary Stratotype Section and Point (ASSP) at the FAD of I. fluctivagus at the Lawson Cove section in the Ibex area of Millard County, Utah, USA. There, strata consist of typical shelly facies limestones that were deposited on a tropical carbonate platform and contain abundant conodonts, trilobites, brachiopods, and other fossil groups. Cambrian and Ordovician strata in this area are ~5300m thick, with the Lawson Cove section spanning 243m in three overlapping segments. Six other measured and studied sections in the area show stratigraphic relationships similar to those at Lawson Cove. Faunas have been used to divide these strata into 14 conodont and 7 trilobite zonal units. The widespread olenid trilobite Jujuyaspis occurs ~90cm above the proposed boundary at Lawson Cove; this genus is generally regarded as earliest Ordovician. Rhynchonelliform and linguliform brachiopods are common to abundant and are useful for correlation. The FAD of Iapetognathus fluctivagus and occurrences of Jujuyaspis and the Lower Ordovician planktonic graptolite Anisograptus matanensis all occur within a 2.4m interval of strata at a nearby section. Non-biological correlation tools include a detailed sequence stratigraphic classification and a detailed carbon-isotope profile. Especially useful for correlation is a positive 13C excursion peak ~15cm below the proposed boundary horizon. All of these correlation tools form an integrated framework that makes the Lawson Cove section especially useful as an ASSP for global correlation of strata with faunas typical of shallow, warm-water, shelly facies.

Detrital zircon U-Pb and (U-Th)/He double-dating of Upper Cretaceous-Cenozoic Zagros foreland basin strata in the Kurdistan Region of northern Iraq

NASA Astrophysics Data System (ADS)

Barber, D. E.; Stockli, D. F.; Koshnaw, R. I.; Horton, B. K.; Tamar-Agha, M. Y.; Kendall, J. J.

2014-12-01

The NW Zagros orogen is the result of the multistage collisional history associated with Late Cretaceous-Cenozoic convergence of the Arabian and Eurasian continents and final closure of Neotethys. Siliciclastic strata preserved within a ~400 km segment of the NW Zagros fold-thrust belt and foreland basin in the Iraqi Kurdistan Region (IKR) provide a widespread record of exhumation and sedimentation. As a means of assessing NW Zagros foreland basin evolution and chronostratigraphy, we present coupled detrital zircon (DZ) U-Pb and (U-Th)/He geo-thermochronometric data of Upper Cretaceous to Pliocene siliciclastic strata from the Duhok, Erbil, and Suleimaniyah provinces of IKR. LA-ICP-MS U-Pb age analyses reveal that the foreland basin fill in IKR in general was dominantly derived from Pan-African/Arabian-Nubian, Peri-Gondwandan, Eurasian, and Cretaceous volcanic arc terrenes. However, the provenance of these strata varies systematically along strike and through time, with an overall increase in complexity upsection. DZ age distribution of Paleocene-Eocene strata is dominated by a ~95 Ma grain age population, likely sourced from the Late Cretaceous Hassanbag-Bitlis volcanic arc complex along the northern margin of Arabia. In contrast, DZ U-Pb age distributions of Neogene strata show a major contribution derived from various Eurasian (e.g., Iranian, Tauride, Pontide; ~45, 150, 300 Ma) and Pan-African (~550, 950 Ma) sources. The introduction of Eurasian DZ ages at the Paleogene-Neogene transition likely records the onset of Arabian-Eurasian collision. Along strike to the southeast, the DZ U-Pb spectra of Neogene strata show a decreased percentage of Pan-African, Peri-Gondwandan, Tauride, and Ordovician ages, coupled with a dramatic increase in 40-50 Ma DZ ages that correspond to Urumieh-Dokhtar magmatic rocks in Iran. Combined with paleocurrent data, this suggests that Neogene sediments were transported longitudinally southeastward through an unbroken foreland basin system and progressively diluted downstream by detritus shed from the Iranian Plateau. Combined (U-Th)/He dating of DZ grains derived from the Hassanbag-Bitlis complex documents a major tectonothermal event at ~75 Ma, corresponding to the timing of proto-Zagros uplift and initial basin development in IKR.

Improvement of core drill methods

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

Gatz, J.L.

1975-07-01

This report documents results of a program to evaluate effectiveness of more or less conventional subsurface samplers in obtaining representative and undisturbed samples of noncohesive alluvial materials containing large quantities of gravels and cobbles. This is the first phase of a research program to improve core drill methods. Samplers evaluated consisted of the Lawrence Livermore Laboratory membrane sampler, 4-in. Denison sampler, 6-in. Dension sampler, 5-in. Modified Denison sampler, and 3-in. thinwall drive tube. Small representative samples were obtained with the Dension samplers; no undisturbed samples were obtained. The field work was accomplished in the Rhodes Canyon area, White Sands Misslemore » Range, New Mexico.« less

Tectonic Processes Along the Southeastern Margin of Alaska - The Neogene Sedimentary Record: Yakataga Formation, St. Elias Mountains

NASA Astrophysics Data System (ADS)

Witmer, J. W.; Ridgway, K. D.; Brennan, P. R.; Arnaud, E.; Pavlis, T.

2008-12-01

Neogene collision of the Yakutat microplate with the southern Alaskan continental margin is associated with extreme rates of exhumation and erosion of the St. Elias Mountains. The exhumation and the concurrent development of temperate glaciers are recorded in the ~5000 m of sedimentary strata of the Yakataga Formation. We present new data from measured stratigraphic sections that document along-strike and temporal changes within the Yakataga Formation along this collisional margin during Miocene to Pleistocene time. In the eastern part of our study area, the Yakataga Formation consists of lenticular sandstone and conglomerate facies associated with fan-delta depositional environments that are overlain by thick-bedded glaciomarine strata. These strata grade to finer-grained sandstone and convoluted mudstone typical of marine shelf environments in the central part of our study area. Along strike in the westernmost part of our study area the Yakataga Formation is interpreted to be laterally equivalent to Neogene strata of the Redwood Formation. These strata include thick-bedded, macrofossil-rich sandstone, well-rounded conglomerate, and thin-bedded mudstone facies that are characteristic of nearshore and shelf depositional environments. These sediments were likely sourced by fluvial systems along the continental margin that served as the backstop for Neogene collision. Preliminary compositional data also suggest that the Redwood Formation was derived from a different source than the Yakataga Formation. Along-strike changes in structural configuration of the Yakataga Formation are also observed. In the easternmost part of our study area adjacent to the Dangerous River zone (DRZ), a possible remnant strike-slip fault system, unconformities between the Yakataga Formation and underlying strata require erosion of 1000s of meters of missing Eocene-Miocene strata. We interpret this part of the mountain range to have undergone the greatest amount of Neogene exhumation. In the central part of the study area, the Yakataga Formation is exposed in a series of growth folds and megachannels that have been incorporated into a southward-propagating thrust belt as sediment was transported westward away from the exhuming St. Elias Range. To the west, more complete stratigraphic sections and finer-grained lithofacies suggest relatively less syndepositional deformation during the deposition of the Yakataga Formation. From a stratigraphic perspective, the DRZ appears to have focused deformation, exhumation, development of temperate glaciers, and westward transport of sediment during deposition of the Yakataga Formation. The westward changes in lithofacies and deformation within the Yakataga Formation are interpreted as products of progressive oblique collision of the Yakutat microplate to the southeastern Alaskan continental margin. New U-Pb detrital zircon geochronologic data from the Yakataga Formation and older underlying strata demonstrate minimal changes in provenance from Eocene to Pleistocene time. We interpret these data to reflect recycling of sediment within the collisional zone.

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.

Estimates of soil erosion using cesium-137 tracer models.

PubMed

Saç, M M; Uğur, A; Yener, G; Ozden, B

2008-01-01

The soil erosion was studied by 137Cs technique in Yatagan basin in Western Turkey, where there exist intensive agricultural activities. This region is subject to serious soil loss problems and yet there is not any erosion data towards soil management and control guidelines. During the soil survey studies, the soil profiles were examined carefully to select the reference points. The soil samples were collected from the slope facets in three different study areas (Kirtas, Peynirli and Kayisalan Hills). Three different models were applied for erosion rate calculations in undisturbed and cultivated sites. The profile distribution model (PDM) was used for undisturbed soils, while proportional model (PM) and simplified mass balance model (SMBM) were used for cultivated soils. The mean annual erosion rates found using PDM in undisturbed soils were 15 t ha(-1) year(-1) at the Peynirli Hill and 27 t ha(-1) year(-1) at the Kirtas Hill. With the PM and SMBM in cultivated soils at Kayişalan, the mean annual erosion rates were obtained to be 65 and 116 t ha(-1) year(-1), respectively. The results of 137Cs technique were compared with the results of the Universal Soil Loss Equation (USLE).

Mobilization of natural colloids from an iron oxide-coated sand aquifer--Effect of pH and ionic strength

USGS Publications Warehouse

Bunn, Rebecca A.; Magelky, Robin D.; Ryan, Joseph N.; Elimelech, Menachem

2002-01-01

Field and laboratory column experiments were performed to assess the effect of elevated pH and reduced ionic strength on the mobilization of natural colloids in a ferric oxyhydroxide-coated aquifer sediment. The field experiments were conducted as natural gradient injections of groundwater amended by sodium hydroxide additions. The laboratory experiments were conducted in columns of undisturbed, oriented sediments and disturbed, disoriented sediments. In the field, the breakthrough of released colloids coincided with the pH pulse breakthrough and lagged the bromide tracer breakthrough. The breakthrough behavior suggested that the progress of the elevated pH front controlled the transport of the mobilized colloids. In the laboratory, about twice as much colloid release occurred in the disturbed sediments as in the undisturbed sediments. The field and laboratory experiments both showed that the total mass of colloid release increased with increasing pH until the concurrent increase in ionic strength limited release. A decrease in ionic strength did not mobilize significant amounts of colloids in the field. The amount of colloids released normalized to the mass of the sediments was similar for the field and the undisturbed laboratory experiments.

Infiltration characteristics of non-aqueous phase liquids in undisturbed loessal soil cores.

PubMed

Wang, Yunqiang; Shao, Ming'an

2009-01-01

The widespread contamination of soils and aquifers by non-aqueous phase liquids (NAPL), such as crude oil, poses serious environmental and health hazards globally. Understanding the infiltration characteristics of NAPL in soil is crucial in mitigating or remediating soil contamination. The infiltration characteristics of crude and diesel oils into undisturbed loessal soil cores, collected in polymethyl methacrylate cylindrical columns, were investigated under a constant fluid head (3 cm) of either crude oil or diesel oil. The infiltration rate of both crude and diesel oils decreased exponentially as wetting depth increased with time. Soil core size and bulk density both had significant effects on NAPL infiltration through the undisturbed soil cores; a smaller core size or a greater bulk density could reduce oil penetration to depth. Compacting soil in areas susceptible to oil spills may be an effective stratage to reduce contamination. The infiltration of NAPL into soil cores was spatially anisotropic and heterogeneous, thus recording the data at four points on the soil core is a good stratage to improve the accuracy of experimental results. Our results revealed that crude and diesel oils, rather than their components, have a practical value for remediation of contaminated loessal soils.

Influence of Disturbance on Soil Respiration in Biologically Crusted Soil during the Dry Season

PubMed Central

Feng, Wei; Zhang, Yu-qing; Wu, Bin; Zha, Tian-shan; Jia, Xin; Qin, Shu-gao; Shao, Chen-xi; Liu, Jia-bin; Lai, Zong-rui; Fa, Ke-yu

2013-01-01

Soil respiration (Rs) is a major pathway for carbon cycling and is a complex process involving abiotic and biotic factors. Biological soil crusts (BSCs) are a key biotic component of desert ecosystems worldwide. In desert ecosystems, soils are protected from surface disturbance by BSCs, but it is unknown whether Rs is affected by disturbance of this crust layer. We measured Rs in three types of disturbed and undisturbed crusted soils (algae, lichen, and moss), as well as bare land from April to August, 2010, in Mu Us desert, northwest China. Rs was similar among undisturbed soils but increased significantly in disturbed moss and algae crusted soils. The variation of Rs in undisturbed and disturbed soil was related to soil bulk density. Disturbance also led to changes in soil organic carbon and fine particles contents, including declines of 60–70% in surface soil C and N, relative to predisturbance values. Once BSCs were disturbed, Q 10 increased. Our findings indicate that a loss of BSCs cover will lead to greater soil C loss through respiration. Given these results, understanding the disturbance sensitivity impact on Rs could be helpful to modify soil management practices which promote carbon sequestration. PMID:24453845

Influence of soil moisture on soil respiration

NASA Astrophysics Data System (ADS)

Fer, Miroslav; Kodesova, Radka; Nikodem, Antonin; Klement, Ales; Jelenova, Klara

2015-04-01

The aim of this work was to describe an impact of soil moisture on soil respiration. Study was performed on soil samples from morphologically diverse study site in loess region of Southern Moravia, Czech Republic. The original soil type is Haplic Chernozem, which was due to erosion changed into Regosol (steep parts) and Colluvial soil (base slope and the tributary valley). Soil samples were collected from topsoils at 5 points of the selected elevation transect and also from the parent material (loess). Grab soil samples, undisturbed soil samples (small - 100 cm3, and large - 713 cm3) and undisturbed soil blocks were taken. Basic soil properties were determined on grab soil samples. Small undisturbed soil samples were used to determine the soil water retention curves and the hydraulic conductivity functions using the multiple outflow tests in Tempe cells and a numerical inversion with HYDRUS 1-D. During experiments performed in greenhouse dry large undisturbed soil samples were wetted from below using a kaolin tank and cumulative water inflow due to capillary rise was measured. Simultaneously net CO2 exchange rate and net H2O exchange rate were measured using LCi-SD portable photosynthesis system with Soil Respiration Chamber. Numerical inversion of the measured cumulative capillary rise data using the HYDRUS-1D program was applied to modify selected soil hydraulic parameters for particular conditions and to simulate actual soil water distribution within each soil column in selected times. Undisturbed soil blocks were used to prepare thin soil sections to study soil-pore structure. Results for all soil samples showed that at the beginning of soil samples wetting the CO2 emission increased because of improving condition for microbes' activity. The maximum values were reached for soil column average soil water content between 0.10 and 0.15 cm3/cm3. Next CO2 emission decreased since the pore system starts filling by water (i.e. aggravated conditions for microbes, closing soil gas pathways etc.). In the case of H2O exchange rate, values increased with increasing soil water contents (up to 0.15-0.20 cm3/cm3) and then remained approximately constant. Acknowledgement: Authors acknowledge the financial support of the Ministry of Agriculture of the Czech Republic No. QJ1230319

Modeling long-term suspended-sediment export from an undisturbed forest catchment

NASA Astrophysics Data System (ADS)

Zimmermann, Alexander; Francke, Till; Elsenbeer, Helmut

2013-04-01

Most estimates of suspended sediment yields from humid, undisturbed, and geologically stable forest environments fall within a range of 5 - 30 t km-2 a-1. These low natural erosion rates in small headwater catchments (≤ 1 km2) support the common impression that a well-developed forest cover prevents surface erosion. Interestingly, those estimates originate exclusively from areas with prevailing vertical hydrological flow paths. Forest environments dominated by (near-) surface flow paths (overland flow, pipe flow, and return flow) and a fast response to rainfall, however, are not an exceptional phenomenon, yet only very few sediment yields have been estimated for these areas. Not surprisingly, even fewer long-term (≥ 10 years) records exist. In this contribution we present our latest research which aims at quantifying long-term suspended-sediment export from an undisturbed rainforest catchment prone to frequent overland flow. A key aspect of our approach is the application of machine-learning techniques (Random Forest, Quantile Regression Forest) which allows not only the handling of non-Gaussian data, non-linear relations between predictors and response, and correlations between predictors, but also the assessment of prediction uncertainty. For the current study we provided the machine-learning algorithms exclusively with information from a high-resolution rainfall time series to reconstruct discharge and suspended sediment dynamics for a 21-year period. The significance of our results is threefold. First, our estimates clearly show that forest cover does not necessarily prevent erosion if wet antecedent conditions and large rainfalls coincide. During these situations, overland flow is widespread and sediment fluxes increase in a non-linear fashion due to the mobilization of new sediment sources. Second, our estimates indicate that annual suspended sediment yields of the undisturbed forest catchment show large fluctuations. Depending on the frequency of large events, annual suspended-sediment yield varies between 74 - 416 t km-2 a-1. Third, the estimated sediment yields exceed former benchmark values by an order of magnitude and provide evidence that the erosion footprint of undisturbed, forested catchments can be undistinguishable from that of sustainably managed, but hydrologically less responsive areas. Because of the susceptibility to soil loss we argue that any land use should be avoided in natural erosion hotspots.

Daily survival rates for nests of Black Skimmers from a core breeding area of the Southeastern USA

USGS Publications Warehouse

Brooks, Gillian L.; Sanders, Felicia J.; Gerard, Patrick D.; Jodice, Patrick G.R.

2014-01-01

Little is known about the reproductive success of Black Skimmers (Rynchops niger) throughout the southeastern USA where availability of undisturbed beaches for nesting is limited. Daily survival rates (DSR) of nests were examined at three nesting sites in Cape Romain National Wildlife Refuge (CRNWR), South Carolina, USA, 2009–2010. The percent of successful nests (n  =  346 nests) ranged from 42–69% among colony sites when data were pooled across both years. The DSR of nests was primarily related to colony site, predation risk, height of high tide, and clutch size. Predation and overwash were the principal causes of identifiable nest loss, each accounting for ∼33% of nest failures during the two study years. Because of the challenges of resighting skimmer chicks, we were not able to measure chick survival effectively and therefore accurate measures of productivity remain elusive. High variability in nest success among sites within close proximity to each other (<20 km) suggests factors at local scales such as disturbance, predation, and overwash events strongly influenced nest success of Black Skimmers during these 2 years as opposed to more region-wide stressors such as tropical storms or food availability. Although time-intensive techniques to control predators do exist, management options to limit flooding and overwash are far more limited. Conservation of Black Skimmers in the southeastern USA would benefit from coordinated, multi-state efforts to measure nest and chick survival.

Stratified and Maximum Information Item Selection Procedures in Computer Adaptive Testing

ERIC Educational Resources Information Center

Deng, Hui; Ansley, Timothy; Chang, Hua-Hua

2010-01-01

In this study we evaluated and compared three item selection procedures: the maximum Fisher information procedure (F), the a-stratified multistage computer adaptive testing (CAT) (STR), and a refined stratification procedure that allows more items to be selected from the high a strata and fewer items from the low a strata (USTR), along with…

Oligocene terrestrial strata of northwestern Ethiopia : a preliminary report on paleoenvironments and paleontology

Treesearch

Bonnie F. Jacobs; Neil Tabor; Mulugeta Feseha; Aaron Pan; John Kappelman; Tab Rasmussen; William Sanders; Michael Wiemann; Jeff Crabaugh; Juan Leandro Garcia Massini

2005-01-01

The Paleogene record of Afro-Arabia is represented by few fossil localities, most of which are coastal. Here we report sedimentological and paleontological data from continental Oligocene strata in northwestern Ethiopia. These have produced abundant plant fossils and unique assemblages of vertebrates, thus filling a gap in what is known of Paleogene interior Afro-...

Side hole drilling in boreholes

NASA Technical Reports Server (NTRS)

Collins, Jr., Earl R. (Inventor)

1980-01-01

Apparatus for use in a borehole or other restricted space to bore a side hole into the strata surrounding the borehole, including a flexible shaft with a drill at its end, and two trains of sheathing members that can be progressively locked together into a rigid structure around the flexible shaft as it is directed sidewardly into the strata.

Implementing a land cover stratification on-the-fly

Treesearch

Ronald E. McRoberts; Daniel G. Wendt

2002-01-01

Stratified estimation is used by the Forest Inventory and Analysis program of the USDA Forest Service to increase the precision of county-level inventory estimates. Stratified estimation requires that plots be assigned to strata and that proportions of land area in each strata be determined. Classified satellite imagery has been found to be an efficient and effective...

The Socialization of Rural College Students: Social Stratification and the Transformation of Living Styles for Rural College Students

ERIC Educational Resources Information Center

Haili, Hu

2015-01-01

Studies of socialization from a stratification perspective stress that while people accept socialization in a broad sense, individual behavior is affected and controlled by special strata relationships and strata culture. This paper sees rural college students as a subculture group and describes their new cultural experiences and the development…

Large Area Crop Inventory Experiment (LACIE). Second-generation sampling strategy evaluation report. [Kansas, North Dakota, and U.S.S.R.

NASA Technical Reports Server (NTRS)

Basu, J. P. (Principal Investigator); Dragich, S. M.; Mcguigan, D. P.

1978-01-01

The author has identified the following significant results. The stratification procedure in the new sampling strategy for LACIE included: (1) correlation test results indicating that an agrophysical stratum may be homogeneous with respect to agricultural density, but not with respect to wheat density; and (2) agrophysical unit homogeneity test results indicating that with respect to agricultural density many agrophysical units are not homogeneous, but removal of one or more refined strata from any such current agrophysical unit can make the strata homogeneous. The apportioning procedure results indicated that the current procedure is not performing well and that the apportioned estimates of refined strata wheat area are often unreliable.

The Strata-1 Regolith Dynamics Experiment: Class 1E Science on ISS

NASA Technical Reports Server (NTRS)

Fries, Marc; Graham, Lee; John, Kristen

2016-01-01

The Strata-1 experiment studies the evolution of small body regolith through long-duration exposure of simulant materials to the microgravity environment on the International Space Station (ISS). This study will record segregation and mechanical dynamics of regolith simulants in a microgravity and vibration environment similar to that experienced by regolith on small Solar System bodies. Strata-1 will help us understand regolith dynamics and will inform design and procedures for landing and setting anchors, safely sampling and moving material on asteroidal surfaces, processing large volumes of material for in situ resource utilization (ISRU) purposes, and, in general, predicting the behavior of large and small particles on disturbed asteroid surfaces. This experiment is providing new insights into small body surface evolution.

Detailed facies analysis of the Upper Cretaceous Tununk Shale Member, Henry Mountains Region, Utah: Implications for mudstone depositional models in epicontinental seas

NASA Astrophysics Data System (ADS)

Li, Zhiyang; Schieber, Juergen

2018-02-01

Lower-Middle Turonian strata of the Tununk Shale Member of the greater Mancos Shale were deposited along the western margin of the Cretaceous Western Interior Seaway during the Greenhorn second-order sea level cycle. In order to examine depositional controls on facies development in this mudstone-rich succession, this study delineates temporal and spatial relationships in a process-sedimentologic-based approach. The 3-dimensional expression of mudstone facies associations and their stratal architecture is assessed through a fully integrative physical and biologic characterization as exposed in outcrops in south-central Utah. Sedimentologic characteristics from the millimeter- to kilometer-scale are documented in order to fully address the complex nature of sediment transport mechanisms observed in this shelf muddy environment. The resulting facies model developed from this characterization consists of a stack of four lithofacies packages including: 1) carbonate-bearing, silty and sandy mudstone (CSSM), 2) silt-bearing, calcareous mudstone (SCM), 3) carbonate-bearing, silty mudstone to muddy siltstone (CMS), and 4) non-calcareous, silty and sandy mudstone (SSM). Spatial and temporal variations in lithofacies type and sedimentary facies characteristics indicate that the depositional environments of the Tununk Shale shifted in response to the 2nd-order Greenhorn transgressive-regressive sea-level cycle. During this eustatic event, the Tununk shows a characteristic vertical shift from distal middle shelf to outer shelf (CSSM to SCM facies), then from outer shelf to inner shelf environment (SCM to CMS, and to SSM facies). Shifting depositional environments, as well as changes in dominant paleocurrent direction throughout this succession, indicate multiple source areas and transport mechanisms (i.e. longshore currents, offshore-directed underflows, storm reworking). This study provides a rare documentation of the Greenhorn cycle as exposed across the entire shelf setting. High-resolution mapping of genetically-related packages facilitate the development of process-based depositional models that can be utilized for lateral correlations into the equivalent foredeep strata of the Cretaceous Interior.

Climatic and biotic controls on annual carbon storage in Amazonian ecosystems

USGS Publications Warehouse

Tian, H.; Melillo, J.M.; Kicklighter, D.W.; McGuire, A.D.; Helfrich, J.; Moore, B.; Vorosmarty, C.J.

2000-01-01

1 The role of undisturbed tropical land ecosystems in the global carbon budget is not well understood. It has been suggested that inter-annual climate variability can affect the capacity of these ecosystems to store carbon in the short term. In this paper, we use a transient version of the Terrestrial Ecosystem Model (TEM) to estimate annual carbon storage in undisturbed Amazonian ecosystems during the period 1980-94, and to understand the underlying causes of the year-to-year variations in net carbon storage for this region. 2 We estimate that the total carbon storage in the undisturbed ecosystems of the Amazon Basin in 1980 was 127.6 Pg C, with about 94.3 Pg C in vegetation and 33.3 Pg C in the reactive pool of soil organic carbon. About 83% of the total carbon storage occurred in tropical evergreen forests. Based on our model's results, we estimate that, over the past 15 years, the total carbon storage has increased by 3.1 Pg C (+ 2%), with a 1.9-Pg C (+2%) increase in vegetation carbon and a 1.2-Pg C (+4%) increase in reactive soil organic carbon. The modelled results indicate that the largest relative changes in net carbon storage have occurred in tropical deciduous forests, but that the largest absolute changes in net carbon storage have occurred in the moist and wet forests of the Basin. 3 Our results show that the strength of interannual variations in net carbon storage of undisturbed ecosystems in the Amazon Basin varies from a carbon source of 0.2 Pg C/year to a carbon sink of 0.7 Pg C/year. Precipitation, especially the amount received during the drier months, appears to be a major controller of annual net carbon storage in the Amazon Basin. Our analysis indicates further that changes in precipitation combine with changes in temperature to affect net carbon storage through influencing soil moisture and nutrient availability. 4 On average, our results suggest that the undisturbed Amazonian ecosystems accumulated 0.2 Pg C/year as a result of climate variability and increasing atmospheric CO2 over the study period. This amount is large enough to have compensated for most of the carbon losses associated with tropical deforestation in the Amazon during the same period. 5 Comparisons with empirical data indicate that climate variability and CO2 fertilization explain most of the variation in net carbon storage for the undisturbed ecosystems. Our analyses suggest that assessment of the regional carbon budget in the tropics should be made over at least one cycle of El Nino-Southern Oscillation because of inter-annual climate variability. Our analyses also suggest that proper scaling of the site-specific and sub-annual measurements of carbon fluxes to produce Basin-wide flux estimates must take into account seasonal and spatial variations in net carbon storage.

Cross-bedding set thickness and stratigraphic architecture of aeolian systems: An example from the Upper Permian Pirambóia Formation (Paraná Basin), southern Brazil

NASA Astrophysics Data System (ADS)

Dias, Kayo Delorenzo Nardi; Scherer, Claiton M. S.

2008-05-01

The Pirambóia Formation comprises an unconformity-bounded aeolian succession essentially composed of three facies associations: aeolian sand sheet, aeolian dune and interdune facies associations. The lower portion of the Pirambóia Formation is characterised by aeolian sand sheet deposits, which are overlain by aeolian dune and interdune strata, hence pointing to an overall increase in sand availability within the paleoerg. The dune and interdune successions can be further subdivided into two distinct stratigraphic intervals in terms of their mean set thickness. Intervals 1 and 2 display mean set thicknesses of 2.9 and 6.19 m, respectively. This increase in the mean set thickness reflects an increase of the angle of climb and/or dune size. In addition to improve the stratigraphic subdivision, the recognition and correlation of intervals with distinct mean set thicknesses provides a tool for reconstructing aeolian erg architecture from drill cores.

Striped bass, temperature, and dissolved oxygen: a speculative hypothesis for environmental risk

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

Coutant, C.C.

1985-01-01

Striped bass Morone saxatilis has a paradoxical record of distribution and abundance, including population declines in coastal waters and variable success of freshwater introductions. This record is analyzed for consistency with a hypothesis that striped bass are squeezed between their thermal and dissolved oxygen preferences or requirements. A commonality among diverse field and laboratory observations supports an inherent thermal niche for the species that changes to lower temperatures as fish age. This shift can cause local conditions, especially warm surface strata and deoxygenated deep water, to be incompatible with the success of large fish. Crowding due to temperature preferences alonemore » or coupled with avoidance of low oxygen concentrations can lead to pathology and overfishing, which may contribute to population declines. Through a mixture of evidence and conjecture, the thermal niche-dissolved oxygen hypothesis is proposed as a unified perspective of the habitat requirements of the species that can aid in its study and management. 139 references, 12 figures.« less

Biostratigraphy and Inoceramus survival across the Cenomanian-Turonian (Cretaceous) boundary in the Ram River section, Alberta, Canada

NASA Astrophysics Data System (ADS)

Walaszczyk, Ireneusz; Plint, A. Guy; Kennedy, William J.

2016-12-01

The biostratigraphy of the uppermost Cenomanian - Lower Turonian succession in the lower part of the Blackstone Formation exposed in the Ram River (Alberta, Canada), is interpreted in terms of the standard inoceramid/ammonite zonation of the interval. Four successive inoceramid zones are recognized, those of Inoceramus pictus, Mytiloides puebloensis, M. kossmati, and M. mytiloides, as established in the stratotype section at Pueblo, Colorado. Their correlation to Pueblo is confirmed by ammonite data. The mid-Early Turonian zone of M. kossmati yielded an assemblage of Inoceramus, with species showing close affinity to the latest Cenomanian lineages. This multi-species sample proves the survival of Inoceramus lineages into the otherwise Mytiloides-dominated Early Turonian, and indicates that their disappearance from the record of the North American Western Interior was not because of their extinction. It is suggested that the apparent lack of Inoceramus in Lower Turonian strata is due to an extremely low population abundance in the Early Turonian sea.

Ants of three adjacent habitats of a transition region between the cerrado and caatinga biomes: the effects of heterogeneity and variation in canopy cover.

PubMed

Neves, F S; Queiroz-Dantas, K S; da Rocha, W D; Delabie, J H C

2013-06-01

Habitat heterogeneity and complexity associated with variations in climatic conditions are important factors determining the structure of ant communities in different terrestrial ecosystems. The objective of this study was to describe the horizontal and vertical distribution patterns of the ant community associated with three adjacent habitats in a transition area between the Cerrado and Caatinga biomes at the Pandeiros River, state of Minas Gerais, Brazil. We tested the following hypotheses: (1) the richness and composition of ant species and functional group structure changes between different habitats and strata; (2) habitats with higher tree species richness and density support higher ant species richness; and (3) habitats with lower variation in canopy cover support higher ant species richness. Sampling was conducted in three adjacent habitats and at three vertical strata. Ant species richness was significantly different among vertical strata. Ant species composition was different among both habitats and vertical strata and functional group structure was divergent among habitats. Partitioning of the diversity revealed that the diversity for the three components was statistically different from the one expected by the null model; α and β 2 were higher and β 1 was lower than the values expected by chance. Tree density and variation in canopy cover negatively affected ant species richness. The occurrence of different species and the changing of functional group structures in different habitats and strata suggest an ecological-evolutionary relationship between ants and their habitats and emphasize the need to implement local conservation strategies in the ecotones between biomes.

Past Human Disturbance Effects upon Biodiversity are Greatest in the Canopy; A Case Study on Rainforest Butterflies.

PubMed

Whitworth, Andrew; Villacampa, Jaime; Brown, Alice; Huarcaya, Ruthmery Pillco; Downie, Roger; MacLeod, Ross

2016-01-01

A key part of tropical forest spatial complexity is the vertical stratification of biodiversity, with widely differing communities found in higher rainforest strata compared to terrestrial levels. Despite this, our understanding of how human disturbance may differentially affect biodiversity across vertical strata of tropical forests has been slow to develop. For the first time, how the patterns of current biodiversity vary between three vertical strata within a single forest, subject to three different types of historic anthropogenic disturbance, was directly assessed. In total, 229 species of butterfly were detected, with a total of 5219 individual records. Butterfly species richness, species diversity, abundance and community evenness differed markedly between vertical strata. We show for the first time, for any group of rainforest biodiversity, that different vertical strata within the same rainforest, responded differently in areas with different historic human disturbance. Differences were most notable within the canopy. Regenerating forest following complete clearance had 47% lower canopy species richness than regenerating forest that was once selectively logged, while the reduction in the mid-storey was 33% and at ground level, 30%. These results also show for the first time that even long term regeneration (over the course of 30 years) may be insufficient to erase differences in biodiversity linked to different types of human disturbance. We argue, along with other studies, that ignoring the potential for more pronounced effects of disturbance on canopy fauna, could lead to the underestimation of the effects of habitat disturbance on biodiversity, and thus the overestimation of the conservation value of regenerating forests more generally.

Past Human Disturbance Effects upon Biodiversity are Greatest in the Canopy; A Case Study on Rainforest Butterflies

PubMed Central

Whitworth, Andrew; Villacampa, Jaime; Brown, Alice; Huarcaya, Ruthmery Pillco; Downie, Roger; MacLeod, Ross

2016-01-01

A key part of tropical forest spatial complexity is the vertical stratification of biodiversity, with widely differing communities found in higher rainforest strata compared to terrestrial levels. Despite this, our understanding of how human disturbance may differentially affect biodiversity across vertical strata of tropical forests has been slow to develop. For the first time, how the patterns of current biodiversity vary between three vertical strata within a single forest, subject to three different types of historic anthropogenic disturbance, was directly assessed. In total, 229 species of butterfly were detected, with a total of 5219 individual records. Butterfly species richness, species diversity, abundance and community evenness differed markedly between vertical strata. We show for the first time, for any group of rainforest biodiversity, that different vertical strata within the same rainforest, responded differently in areas with different historic human disturbance. Differences were most notable within the canopy. Regenerating forest following complete clearance had 47% lower canopy species richness than regenerating forest that was once selectively logged, while the reduction in the mid-storey was 33% and at ground level, 30%. These results also show for the first time that even long term regeneration (over the course of 30 years) may be insufficient to erase differences in biodiversity linked to different types of human disturbance. We argue, along with other studies, that ignoring the potential for more pronounced effects of disturbance on canopy fauna, could lead to the underestimation of the effects of habitat disturbance on biodiversity, and thus the overestimation of the conservation value of regenerating forests more generally. PMID:26950438

Palynology of late Middle Pennsylvanian coal beds in the Appalachian Basin

USGS Publications Warehouse

Eble, C.F.

2002-01-01

Fossil spores and pollen have long been recognized as valuable tools for identifying and correlating coal beds. This paper describes the palynology of late Middle Pennsylvanian coal beds in the Appalachian Basin with emphasis on forms that assist both intra- and interbasinal coal bed correlation. Stratigraphically important palynomorphs that originate in late Middle Pennsylvanian strata include Torispora securis, Murospora kosankei, Triquitrites minutus, Cadiospora magna, Mooreisporites inusitatus, and Schopfites dimorphus. Taxa that terminate in the late Middle Pennsylvanian include Radiizonates difformis, Densosporites annulatus, Dictyotriletes bireticulatus, Vestispora magna, and Savitrisporites nux. Species of Lycospora, Cirratriradites, Vestispora, and Thymospora, as well as Granasporites medius, Triquitrites sculptilis, and T. securis and their respective ranges slightly higher, in earliest Late Pennsylvanian age strata. Late Middle Pennsylvanian and earliest Late Pennsylvanian strata in the Appalachian Basin correlate with the Radiizonates difformis (RD), Mooreisporites inusitatus (MI), Schopfites colchesterensis-S. dimorphus (CP), and Lycospora granulata-Granasporites medius (GM) spore assemblage zones of the Eastern Interior, or Illinois Basin. In the Western Interior Basin, these strata correlate with the middle-upper portion of the Torispora securis-Laevigatosporites globosus (SG) and lower half of the Thymospora pseudothiessenii-Schopfites dimorphus (PD) assemblage zones. In western Europe, late Middle Pennsylvanian and earliest Late Pennsylvanian strata correlate with the middle-upper portion of the Torispora securis-T. laevigata (SL) and the middle part of the Thymospora obscura-T. thiessenii (OT) spore assemblage zones. Allegheny Formation coal beds also correlate with the Torispora securis (X) and Thymospora obscura (XI) spore assemblages, which were developed for coal beds in Great Britain. ?? 2002 Elsevier Science B.V. All rights reserved.

Petroleum prospects for offshore sedimentary basins in the eastern Papua New Guinea and Solomon Islands regions

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

Bruns, T.R.; Vedder, J.G.

Intra-arc basins in the Buka-Bougainville region of Papua New Guinea and in the Solomon Islands contain thick sedimentary sequences that may be prospective for petroleum. The Queen Emma basin, between Bougainville and New Ireland, contains as much as 8 km of deformed Oligocene and younger strata. The Central Solomons Trough, which underlies New Georgia Sound, is a composite intra-arc basin that contains late Oligocene and younger strata as much as 7 km thick. Farther east, beneath Indispensable Strait, the down-faulted Indispensable basin locally contains as much as 5.4 km of Miocene( ) and younger strata, and the offshore part ofmore » Mbokokimbo basin off eastern Guadalcanal includes 6 km or more of late Miocene and younger strata. All of these basins have some of the attributes necessary to generate and trap petroleum. Structural and stratigraphic traps are common, including faulted anticlines, sedimentary wedges, and carbonate reefs and reef-derived deposits on submarine ridges and along the basin margins. The thickness of the basin deposits ensures that some strata are buried deeply enough to be within the thermal regime required for hydrocarbon generation. However, little source or reservoir rock information is available because of the lack of detailed surface and subsurface stratigraphy. Moreover, much of the basin sediment is likely to consist of volcaniclastic material, derived from uplifted volcanogenic rocks surrounding the basins, and may be poor in source and reservoir rocks. Until additional stratigraphic information is available, analysis of the petroleum potential of these basins is a matter of conjecture.« less

Detrital zircon microtextures and U-PB geochronology of Upper Jurassic to Paleocene strata in the distal North American Cordillera foreland basin

NASA Astrophysics Data System (ADS)

Finzel, E. S.

2017-07-01

Detrital zircon surface microtextures, geochronologic U-Pb data, and tectonic subsidence analysis from Upper Jurassic to Paleocene strata in the Black Hills of South Dakota reveal provenance variations in the distal portion of the Cordillera foreland basin in response to tectonic events along the outboard margin of western North America. During Late Jurassic to Early Cretaceous time, nonmarine strata record initially low rates of tectonic subsidence that facilitated widespread recycling of older foreland basin strata in eolian and fluvial systems that dispersed sediment to the northeast, with minimal sediment derived from the thrust belt. By middle Cretaceous time, marine inundation reflects increased subsidence rates coincident with a change to eastern sediment sources. Lowstand Albian fluvial systems in the Black Hills may have been linked to fluvial systems upstream in the midcontinent and downstream in the Bighorn Basin in Wyoming. During latest Cretaceous time, tectonic uplift in the study area reflects dynamic processes related to Laramide low-angle subduction that, relative to other basins to the west, was more influential due to the greater distance from the thrust load. Provenance data from Maastrichtian and lower Paleocene strata indicate a change back to western sources that included the Idaho-Montana batholith and exhumed Belt Supergroup. This study provides a significant contribution to the growing database that is refining the tectonics and continental-scale sediment dispersal patterns in North America during Late Jurassic-early Paleocene time. In addition, it demonstrates the merit of using detrital zircon grain shape and surface microtextures to aid in provenance interpretations.

Seismic reflection profile of the Blake Ridge near sites 994, 995, and 997: Chapter 4

USGS Publications Warehouse

Dillon, William P.; Hutchinson, Deborah R.; Drury, Rebecca M.

1996-01-01

Seismic reflection profiles near Sites 994, 995, and 997 were collected with seismic sources that provide maximum resolution with adequate power to image the zone of gas hydrate stability and the region direction beneath it. The overall structure of the sediment drift deposit that constitutes the Blake Ridge consists of southwestward-dipping strata. These strata are approximately conformal to the seafloor on the southwest side of the ridge and are truncated by erosion on the northeast side. A bottom-simulating reflection (BSR) marks the velocity contrast between gas hydrate-bearing sediment and regions containing free gas beneath the zone of gas hydrate stability. The BSR is strong and continuous near the ridge crest but becomes discontinuous on the flanks, where concentration of gas is reduced and dipping strata pass through the level of the base o fgas hydrate stability or the strata are disrupted by faults. Seismic reflection amplitudes appear to be reduced in the region of gas hydrate formation compared to normal amplitudes. A faulted zone ~0.5-0.6 s thick parallels reflections from strata. We infer that this may represent a formerly gas hydrate-bearing zone that was faulted because of a breakdown of hydrate near its phase limit (at the base of the zone). Strong reflections at the top of the faulted zone are caused by free-gas acccumulation at Site 994. Similar strong reflections probably are caused by free-gas accumulations where the top of the faulted zone rises above the BSR, although this would require local free gas within the hydrate-stable zone.

25 CFR 213.33 - Diligence and prevention of waste.

Code of Federal Regulations, 2013 CFR

2013-04-01

... the same and to shut off effectually all water from the oil or gas-bearing strata; not drill any well... prevention of waste of oil or gas developed on the land, or the entrance of water through wells drilled by the lessee to the productive sands or oil or gas-bearing strata to the destruction or injury of the...

Modeling of multi-strata forest fire severity using Landsat TM data

Treesearch

Q. Meng; R.K. Meentemeyer

2011-01-01

Most of fire severity studies use field measures of composite burn index (CBI) to represent forest fire severity and fit the relationships between CBI and Landsat imagery derived differenced normalized burn ratio (dNBR) to predict and map fire severity at unsampled locations. However, less attention has been paid on the multi-strata forest fire severity, which...

A comparison of stratification effectiveness between the National Land Cover Data set and photointerpretation in western Oregon

Treesearch

Paul Dunham; Dale Weyermann; Dale Azuma

2002-01-01

Stratifications developed from National Land Cover Data (NLCD) and from photointerpretation (PI) were tested for effectiveness in reducing sampling error associated with estimates of timberland area and volume from FIA plots in western Oregon. Strata were created from NLCD through the aggregation of cover classes and the creation of 'edge' strata by...

Permian macro- and miofloral diversity, palynodating and palaeoclimate implications deduced from the coal-bearing sequences of Singrauli coalfield, Son-Mahanadi Basin, central India

NASA Astrophysics Data System (ADS)

Singh, Kamal Jeet; Murthy, Srikanta; Saxena, Anju; Shabbar, Husain

2017-03-01

The coal-bearing sequences of Barakar and Raniganj formations exposed in Bina and Jhingurdah open-cast collieries, respectively, are analysed for their macro- and miofloral content. The sediment successions primarily comprise of sandstones, shales, claystones and coal seams. In addition to the diverse glossopterid assemblage, four palynoassemblage zones, namely Zones I and II in Bina Colliery and Zones III and IV in Jhingurdah Colliery, have also been recorded in the present study. The megafossil assemblage from the Barakar strata of Bina Colliery comprises of three genera, namely Gangamopteris, Glossopteris and cf. Noeggerathiopsis. Palynoassemblage-I is characterised by the dominance of non-striate bisaccate pollen genus Scheuringipollenites and subdominance of striate bisaccate Faunipollenites and infers these strata to be of Early Permian (Artinskian) age (Lower Barakar Formation). The palynoassemblage has also yielded a large number of naked fossil spore tetrads, which is the first record of spore tetrads from any Artinskian strata in the world and has a significant bearing on the climatic conditions. The palynoassemblage-II is characterised with the dominance of Faunipollenites over Scheuringipollenites and is indicative of Kungurian age (Upper Barakar Formation). The megafossil assemblage from the Raniganj Formation of Jhingurdah Colliery comprises of five genera with 26 species representing four orders, viz., Equisetales, Cordaitales, Cycadales and Glossopteridales. The order Glossopteridales is highly diversified with 23 taxa and the genus Glossopteris, with 22 species, dominates the flora. The mioflora of this colliery is represented by two distinct palynoassemblages. The palynoassemblage-III is correlatable with the palynoflora of Early Permian (Artinskian) Lower Barakar Formation. The assemblage suggests the continuity of older biozones into the younger ones. The palynoassemblage-IV equates the beds with composition V: Striatopodocarpites-Faunipollenites-Gondisporites assemblage zone of Tiwari and Tripathi (1992) of Late Permian (Lopingian) Raniganj Formation in Damodar Basin. The FAD's of Alisporites, Klausipollenites, Falcisporites, Arcuatipollenites pellucidus and Playfordiaspora cancellosa palynotaxa in this assemblage enhance the end Permian level of the Jhingurdah Top seam, as these elements are the key species to mark the transition of Permian into the Lower Triassic.

Predicting temporal changes in total iron concentrations in groundwaters flowing from abandoned deep mines: a first approximation

NASA Astrophysics Data System (ADS)

Younger, Paul L.

2000-06-01

Discharges of contaminated groundwater from abandoned deep mines are a major environmental problem in many parts of the world. While process-based models of pollutant generation have been successfully developed for certain surface mines and waste rock piles of relatively simple geometry and limited areal extent, such models are not readily applicable to large systems of laterally extensive, interconnected, abandoned deep mines. As a first approximation for such systems, hydrological and lithological factors, which can reasonably be expected to influence pollutant release, have been assessed by empirically assessing data from 81 abandoned deep coal mine discharges in the UK. These data demonstrate that after flooding of a deep mine is complete and groundwater begins to migrate from the mine voids into surface waters or adjoining aquifers, flushing of the mine voids by fresh recharge results in a gradual improvement in the quality of groundwater (principally manifested as decreasing Fe concentrations and stabilisation of pH around 7). Alternative representations of the flushing process have been examined. While elegant analytical solutions of the advection-dispersion equation can be made to mimic the changes in iron concentration, parameterisation is tendentious in practice. Scrutiny of the UK data suggest that to a first approximation, the duration of the main period of flushing can be predicted to endure around four times as long as the foregoing process of mine flooding. Short- and long-term iron concentrations (i.e. at the start of the main period of flushing and after its completion, respectively) can be estimated from the sulphur content of the worked strata. If strata composition data are unavailable, some indication of pollution potential can be obtained from considerations of the proximity of worked strata to marine beds (which typically have high pyrite contents). The long-term concentrations of iron in a particular discharge can also be approximated on the basis of the proximity of the discharge location to the outcrop of the most closely associated coal seam (MCACS) and, thus, to zones of possible ongoing pyrite oxidation. The practical application of these simple predictive techniques is facilitated by means of a flowchart.

Characterization of the seismically imaged Tuscarora fold system and implications for layer parallel shortening in the Pennsylvania salient

NASA Astrophysics Data System (ADS)

Mount, Van S.; Wilkins, Scott; Comiskey, Cody S.

2017-12-01

The Tuscarora fold system (TFS) is located in the Pennsylvania salient in the foreland of the Valley and Ridge province. The TFS is imaged in high quality 3D seismic data and comprises a system of small-scale folds within relatively flat-lying Lower Silurian Tuscarora Formation strata. We characterize the TFS structures and infer layer parallel shortening (LPS) directions and magnitudes associated with deformation during the Alleghany Orogeny. Previously reported LPS data in our study area are from shallow Devonian and Carboniferous strata (based on outcrop and core analyses) above the shallowest of three major detachments recognized in the region. Seismic data allows us to characterize LPS at depth in strata beneath the shallow detachment. Our LPS data (orientations and inferred magnitudes) are consistent with the shallow data leading us to surmise that LPS during Alleghanian deformation fanned around the salient and was distributed throughout the stratigraphic section - and not isolated to strata above the shallow detachment. We propose that a NW-SE oriented Alleghanian maximum principal stress was perturbed by deep structure associated with the non-linear margin of Laurentia resulting in fanning of shortening directions within the salient.

An overview of paleogene molluscan biostratigraphy and paleoecology of the Gulf of Alaska region

USGS Publications Warehouse

Marincovich, L.; McCoy, S.

1984-01-01

Paleogene marine strata in the Gulf of Alaska region occur in three geographic areas and may be characterized by their molluscan faunal composition and paleoecology: a western area consisting of the Alaska Peninsula, Kodiak Island, and adjacent islands; a central area encompassing Prince William Sound; and an eastern area extending from the mouth of the Copper River to Icy Point in the Lituya district. Strata in the western area include the Ghost Rocks, Narrow Cape (in part), Sitkalidak, Stepovak, Belkofski, and Tolstoi Formations; in the central area Paleogene strata are assigned entirely to the Orca Group; Paleogene strata in the eastern area include the Kulthieth and Poul Creek Formations and several coeval units. Environments ranging from marginal marine to bathyal and from subtropical to cool-temperate are inferred for the various molluscan faunas. Sediments range from interbedded coal and marine sands to deep-water turbidites. The known Paleogene molluscan faunas of these three southern Alaskan areas permit recognition of biostratigraphic schemes within each area, preliminary correlations between faunas of the three areas, and more general correlations with faunas of the Pacific Northwest, the Far Eastern U.S.S.R., and northern Japan. ?? 1984.

Checklist of Gastropods from the Exclusive Economic Zone (EEZ), Sarawak, Malaysia

PubMed Central

Morni, Wan Zabidii Wan; Rahim, Siti Akmar Khadijah Ab; Rumpet, Richard; Musel, Jamil; Hassan, Ruhana

2017-01-01

This study provides the first marine gastropod checklist from the Sarawak Exclusive Economic Zone (EEZ). Gastropod samples were collected from selected stations in the Sarawak EEZ using an otter trawl net with a stretched mesh size of 38 mm at the cod end. The trawling operations were conducted more than 12 nautical miles from the coast, and the area was divided into three depth strata: I) 20–50 m, II) 50–100 m and III) 100–200 m. A total of 23 gastropod species were identified during the two-month sampling period from 16 August until 6 October 2015, representing 8 superfamilies, 15 families and 20 genera. Superfamily Tonnoidea was represented by 7 species, followed by Muricoidea (5 species), Cypraeoidea (4 species), and Buccinoidea and Conoidea (both with 2 species). Other superfamilies were represented by a single species. Only 3 species were obtained in 2 depth strata, namely Melo melo, Murex aduncospinosus and Tonna galea. In addition, 9, 13 and 4 species of gastropods were found in strata I, II and III, respectively. The information on gastropod distributions at different depth strata in the Sarawak EEZ could be useful in updating the Malaysian species diversity database. PMID:28228920

Checklist of Gastropods from the Exclusive Economic Zone (EEZ), Sarawak, Malaysia.

PubMed

Morni, Wan Zabidii Wan; Rahim, Siti Akmar Khadijah Ab; Rumpet, Richard; Musel, Jamil; Hassan, Ruhana

2017-01-01

This study provides the first marine gastropod checklist from the Sarawak Exclusive Economic Zone (EEZ). Gastropod samples were collected from selected stations in the Sarawak EEZ using an otter trawl net with a stretched mesh size of 38 mm at the cod end. The trawling operations were conducted more than 12 nautical miles from the coast, and the area was divided into three depth strata: I) 20-50 m, II) 50-100 m and III) 100-200 m. A total of 23 gastropod species were identified during the two-month sampling period from 16 August until 6 October 2015, representing 8 superfamilies, 15 families and 20 genera. Superfamily Tonnoidea was represented by 7 species, followed by Muricoidea (5 species), Cypraeoidea (4 species), and Buccinoidea and Conoidea (both with 2 species). Other superfamilies were represented by a single species. Only 3 species were obtained in 2 depth strata, namely Melo melo , Murex aduncospinosus and Tonna galea . In addition, 9, 13 and 4 species of gastropods were found in strata I, II and III, respectively. The information on gastropod distributions at different depth strata in the Sarawak EEZ could be useful in updating the Malaysian species diversity database.

Sedimentary structures and textures of Rio Orinoco channel sands, Venezuela and Colombia

USGS Publications Warehouse

McKee, Edwin Dinwiddie

1989-01-01

Most sedimentary structures represented in sand bodies of the Rio Orinoco are tabular-planar cross-strata which, together with some wedge-planar cross-strata, are the products of sand-wave deposition. Locally, in areas of river meander where point bars characteristically form, trough structures forming festoon patterns are numerous. At a few localities, sets of nearly horizontal strata occur between tabular-planar sets and are interpreted to be the deposits of very fast currents of the upper flow regime; elsewhere, uncommon lenses and beds of silt, clay, or organic matter consisting of leaves and twigs, seem to be the result of quiet-water settling through gravity. By far the most common grain size represented in the tabular-planar and wedge-planar cross-strata of the sandwave deposits is medium sand (? - ? millimeter) as determined by screen analyses. Many samples, however, also contain moderate quantities of coarse or very coarse sand. Eolian dunes on top of the sand-wave deposits are dominantly fine grained. The river channel sands were determined to be largely moderately well sorted, although in some places they were mostly well sorted, and in others, mostly moderately sorted.

Regional management of farmland feeding geese using an ecological prioritization tool.

PubMed

Madsen, Jesper; Bjerrum, Morten; Tombre, Ingunn M

2014-10-01

Wild geese foraging on farmland cause increasing conflicts with agricultural interests, calling for a strategic approach to mitigation. In central Norway, conflicts between farmers and spring-staging pink-footed geese feeding on pastures have escalated. To alleviate the conflict, a scheme by which farmers are subsidized to allow geese to forage undisturbed was introduced. To guide allocation of subsidies, an ecological-based ranking of fields at a regional level was recommended and applied. Here we evaluate the scheme. On average, 40 % of subsidized fields were in the top 5 % of the ranking, and 80 % were within the top 20 %. Goose grazing pressure on subsidized pastures was 13 times higher compared to a stratified random selection of non-subsidized pastures, capturing 67 % of the pasture feeding geese despite that subsidized fields only comprised 13 % of the grassland area. Close dialogue between scientists and managers is regarded as a key to the success of the scheme.

Remote sensing and landslide hazard assessment

NASA Technical Reports Server (NTRS)

Mckean, J.; Buechel, S.; Gaydos, L.

1991-01-01

Remotely acquired multispectral data are used to improve landslide hazard assessments at all scales of investigation. A vegetation map produced from automated interpretation of TM data is used in a GIS context to explore the effect of vegetation type on debris flow occurrence in preparation for inclusion in debris flow hazard modeling. Spectral vegetation indices map spatial patterns of grass senescence which are found to be correlated with soil thickness variations on hillslopes. Grassland senescence is delayed over deeper, wetter soils that are likely debris flow source areas. Prediction of actual soil depths using vegetation indices may be possible up to some limiting depth greater than the grass rooting zone. On forested earthflows, the slow slide movement disrupts the overhead timber canopy, exposes understory vegetation and soils, and alters site spectral characteristics. Both spectral and textural measures from broad band multispectral data are successful at detecting an earthflow within an undisturbed old-growth forest.

Selective REM-sleep deprivation does not diminish emotional memory consolidation in young healthy subjects.

PubMed

Morgenthaler, Jarste; Wiesner, Christian D; Hinze, Karoline; Abels, Lena C; Prehn-Kristensen, Alexander; Göder, Robert

2014-01-01

Sleep enhances memory consolidation and it has been hypothesized that rapid eye movement (REM) sleep in particular facilitates the consolidation of emotional memory. The aim of this study was to investigate this hypothesis using selective REM-sleep deprivation. We used a recognition memory task in which participants were shown negative and neutral pictures. Participants (N=29 healthy medical students) were separated into two groups (undisturbed sleep and selective REM-sleep deprived). Both groups also worked on the memory task in a wake condition. Recognition accuracy was significantly better for negative than for neutral stimuli and better after the sleep than the wake condition. There was, however, no difference in the recognition accuracy (neutral and emotional) between the groups. In summary, our data suggest that REM-sleep deprivation was successful and that the resulting reduction of REM-sleep had no influence on memory consolidation whatsoever.

SEDIMENT-HOSTED PRECIOUS METAL DEPOSITS.

USGS Publications Warehouse

Bagby, W.C.; Pickthorn, W.J.; Goldfarb, R.; Hill, R.A.

1984-01-01

The Dee mine is a sediment-hosted, disseminated gold deposit in the Roberts Mountains allochthon of north central Nevada. Soil samples were collected from the C-horizon in undisturbed areas over the deposit in order to investigate the usefulness of soil geochemistry in identifying this type of deposit. Each sample was sieved to minus 80 mesh and analyzed quantitatively for Au, Ag, As, Sb, Hg, Tl and semi-quantitative data for an additional 31 elements. Rank sum analysis is successful for the Au, Ag, As, Sb, Hg, Tl suite, even though bedrock geology is disregarded. This method involves data transformation into a total element signature by ranking the data in ascending order and summing the element ranks for each sample. The rank sums are then divided into percentile groups and plotted. The rank sum plot for the Dee soils unequivocally identifies three of four known ore zones.

Recognizing critical mine spoil health characteristics to design ...

EPA Pesticide Factsheets

Biochar can be used as an amendment to remediate metal-contaminated mine spoils for improved site phytostabilization. For successful phytostabilization to occur, biochar amendments must improve mine spoil health with respect to plant rooting plus uptake of water and nutrients. An inappropriate biochar may negatively impact plant growth conditions resulting in poor plant establishment and growth. Matching the appropriate biochar for each mine site requires reconnaissance of spoil chemical and physical conditions and then identifying which properties need rectified to promote plant growth. A rectification hierarchy needs to be established with the primary limiting factor being addressed first, then successive limitations addressed simultaneously or thereafter. We posit that spoils at each site will have a unique chemical, physical, and biological signature that will affect plant growth. For example, some spoils may be extremely acidic, possess phytotoxic concentrations of heavy metals, or have physical conditions that limits water storage and root penetration. Quantifying these and other conditions beforehand allows for the production of designer biochar with specific characteristics tailored for specific plant growth deficiencies within each spoil. Additionally, we recommend the use of proximally located, undisturbed soils to establish spoil remediation targets. In our work, we have developed a decision-tree flow-chart that identifies salient chemical,

Neoproterozoic diamictite-cap carbonate succession and δ13C chemostratigraphy from eastern Sonora, Mexico

USGS Publications Warehouse

Corsetti, Frank A.; Stewart, John H.; Hagadorn, James W.

2007-01-01

Despite the occurrence of Neoproterozoic strata throughout the southwestern U.S. and Sonora, Mexico, glacial units overlain by enigmatic cap carbonates have not been well-documented south of Death Valley, California. Here, we describe in detail the first glaciogenic diamictite and cap carbonate succession from Mexico, found in the Cerro Las Bolas Group. The diamictite is exposed near Sahuaripa, Sonora, and is overlain by a 5 m thick very finely-laminated dolostone with soft sediment folds. Carbon isotopic chemostratigraphy of the finely-laminated dolostone reveals a negative δ13C anomaly (down to − 3.2‰ PDB) characteristic of cap carbonates worldwide. Carbon isotopic values rise to + 10‰ across ∼ 400 m of section in overlying carbonates of the Mina el Mezquite and Monteso Formations. The pattern recorded here is mostly characteristic of post-Sturtian (ca. ≤ 700 Ma), but pre-Marinoan (ca. ≥ 635 Ma) time. However, the Cerro Las Bolas Group shares ambiguity common to most Neoproterozoic successions: it lacks useful radiometric age constraints and biostratigraphically useful fossils, and its δ13C signature is oscillatory and therefore somewhat equivocal.

Structure and petroleum potential of the continental margin between Cross Sound and Icy Bay, northern Gulf of Alaska

USGS Publications Warehouse

Bruns, T.R.

1982-01-01

Major structural features of the Yakutat segment, the segment of the continental margin between Cross Sound and Icy Bay, northern Gulf of Alaska, are delineated by multichannel seismic reflection data. A large structural high is centered on Fairweather Ground and lies generally at the edge of the shelf from Cross Sound to west of the Alsek Valley. A basement uplift, the Dangerous River zone, along which the seismic acoustic basement shallows by up to two kilometers, extends north from the western edge of Fairweather Ground towards the mouth of the Dangerous River. The Dangerous River zone separates the Yakutat segment into two distinct subbasins. The eastern subbasin has a maximum sediment thickness of about 4 km, and the axis of the basin is near and parallel to the coast. Strata in this basin are largely of late Cenozoic age (Neogene and Quaternary) and approximately correlate with the onshore Yakataga Formation. The western subbasin has a maximum of at least 9 km of sediment, comprised of a thick (greater than 4.5 km) Paleogene section overlain by late Cenozoic strata. The Paleogene section is truncated along the Dangerous River zone by a combination of erosion, faulting, and onlap onto the acoustic basement. Within the western subbasin, the late Cenozoic basin axis is near and parallel to the coast, but the Paleogene basin axis appears to trend in a northwest direction diagonally across the shelf. Sedimentary strata throughout the Yakutat shelf show regional subsidence and only minor deformation except in the vicinity of the Fairweather Ground structural high, near and along the Dangerous River zone, and at the shoreline near Lituya Bay. Seismic data across the continental slope and adjacent deep ocean show truncation at the continental slope of Paleogene strata, the presence of a thick (to 6 km) undeformed or mildly deformed abyssal sedimentary section at the base of the slope that in part onlaps the slope, and a relatively narrow zone along the slope or at the base of the slope where faulting may have occurred. Observed deformation at the base of the slope is primarily related to the late Cenozoic uplift of Fairweather Ground, and to Quaternary folding perpendicular to the Pacific-North America relative convergence vector. No accretionary section or major deformation is observed along the continental slope. The absence of these features suggests that no major subduction of the Pacific plate beneath the Yakutat margin has occurred during the late Cenozoic. However, transform faulting along the base of the slope has occurred, because probable Oligocene oceanic basement is juxtaposed against Mesozoic and Paleogene sedimentary strata of the Yakutat slope. This juxtaposition most likely occurred during late Oligocene and Miocene time. During much of the late Cenozoic, and especially during Pliocene-Pleistocene time, the Yakutat segment has apparently been moving northward with the Pacific plate. Dredge samples from the continental slope recovered potential hydrocarbon source and reservoir rocks from the Paleogene sedimentary sequence. Most of the organic matter from these samples is immature to marginally mature. Lopatin calculations suggest that rocks beneath the shelf are likely to be thermally mature at a depth of 4 to 5 km and deeper. In general, the strata at these depths are largely of Paleogene age. Thus, the Paleogene strata may have significant resource potential if source and reservoir rocks similar to those dredged at the slope are present below the shelf. The Paleogene strata are contained primarily within the western subbasin; strata in the east subbasin appear to have little resource potential. Structural traps are apparently present in parts of the basin near and along the Dangerous River zone. These traps are in an updip position from potentially mature strata of the western subbasin, and may hold commercial accumulations of hydrocarbons, if sufficient hydrocarbon generation and migration has occurred

Pressure changes and their effects on the Cerro Prieto geothermal field

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

Bermejo M, F.J.; Navarro O, F.X.; Esquer P, C.A.

1981-01-01

Continuous extraction of the water-steam mixture at the field has been increasing to fulfill the steam requirements of the power plant. As a result, pressure declines have been observed in the producing strata in all of the wells, as well as in the geothermal reservoir as a whole. Anomalous behavior that has been observed in the wells' hydraulic columns in most cases is due to the interconnection of the various strata penetrated by the well. When this occurs, unbalanced hydraulic pressures cause the movement of fluids between the strata. As an example of this hydraulic imbalance causing the flow ofmore » fluids from an upper to a lower zone, well Nuevo Leon 1 where this effect occurs between regions 600 m apart was chosen.« less

Effects of grazing on nesting by upland sandpipers in southcentral North Dakota

USGS Publications Warehouse

Bowen, Bonnie S.; Kruse, Arnold D.

1993-01-01

Grazing by livestock is often used to reduce litter, improve plant vigor, and alter plant species composition, but additional information is needed on the effects of these management practices on upland-nesting birds. Thus, we conducted an experimental study of the effect of grazing on nest density and nest success of upland sandpipers (Bartramia longicauda) in southcentral North Dakota from 1981 to 1987. Our experimental design consisted of 4 treatments and 1 control, each applied to 1 field in each of 3 study areas. The treatments represented options available to grassland managers: spring grazing, autumn grazing, autumn-and-spring grazing, season-long grazing, and control (ungrazed during the study). Nests (n = 342) were found by searching study areas with a cable-chain drag. Nest density was lower (P = 0.006) for treatments where cattle were present (spring, autumn-and-spring, and season-long) than where cattle were not present (autumn and control) during the nesting season. We concluded that grazing during the nesting season reduced the nest density of upland sandpipers. Nest success varied among years (P = 0.01) and was low in the first year of grazing and higher at the end of the study period. We found little evidence that the grazing treatment influenced nest success. We recommend that public lands with breeding populations of upland sandpipers include a complex of fields under various management practices, including fields undisturbed during the nesting season.

Cenozoic tectonic reorganizations of the Death Valley region, southeast California and southwest Nevada

USGS Publications Warehouse

Fridrich, Christopher J.; Thompson, Ren A.

2011-01-01

The Death Valley region, of southeast California and southwest Nevada, is distinct relative to adjacent regions in its structural style and resulting topography, as well as in the timing of basin-range extension. Cenozoic basin-fill strata, ranging in age from greater than or equal to 40 to approximately 2 million years are common within mountain-range uplifts in this region. The tectonic fragmentation and local uplift of these abandoned basin-fills indicate a multistage history of basin-range tectonism. Additionally, the oldest of these strata record an earlier, pre-basin-range interval of weak extension that formed broad shallow basins that trapped sediments, without forming basin-range topography. The Cenozoic basin-fill strata record distinct stratigraphic breaks that regionally cluster into tight age ranges, constrained by well-dated interbedded volcanic units. Many of these stratigraphic breaks are long recognized formation boundaries. Most are angular unconformities that coincide with abrupt changes in depositional environment. Deposits that bound these unconformities indicate they are weakly diachronous; they span about 1 to 2 million years and generally decrease in age to the west within individual basins and regionally, across basin boundaries. Across these unconformities, major changes are found in the distribution and provenance of basin-fill strata, and in patterns of internal facies. These features indicate rapid, regionally coordinated changes in strain patterns defined by major active basin-bounding faults, coincident with step-wise migrations of the belt of active basin-range tectonism. The regionally correlative unconformities thus record short intervals of radical tectonic change, here termed "tectonic reorganizations." The intervening, longer (about 3- to 5-million-year) interval of gradual, monotonic evolution in the locus and style of tectonism are called "tectonic stages." The belt of active tectonism in the Death Valley region has abruptly stepped westward during three successive tectonic reorganizations that intervened between four stages of basin-range tectonism, the youngest of which is ongoing. These three tectonic reorganizations also intervened between four stages of volcanic activity, each of which has been distinct in the compositions of magmas erupted, in eruption rates, and in the locus of volcanic activity—which has stepped progressively westward, in close coordination with the step-wise migrations in the locus of basin-range extension. The timing of the Cenozoic tectonic reorganizations in the Death Valley region correlates closely with the documented timing of episodic reorganizations of the boundary between the Pacific and North American plates, to the west and southwest. This supports models that explain the widely distributed transtensional tectonism in southwestern North America since approximately 40 million years ago as resulting from traction imposed by the adjacent, divergent Pacific plate.

Effects of a chemical weapons incineration plant on red-tailed tropicbirds

USGS Publications Warehouse

Schreiber, E.A.; Doherty, P.F.; Schenk, G.A.

2001-01-01

From 1990 to 2000, the Johnston Atoll Chemical Agent Disposal System (JACADS) incinerated part of the U.S. stockpile of chemical weapons on Johnston Atoll, central Pacific Ocean, which also is a National Wildlife Refuge and home to approximately a half-million breeding seabirds. The effect on wildlife of incineration of these weapons is unknown. Using a multi-strata mark-recapture analysis, we investigated the effects of JACADS on reproductive success, survival, and movement probabilities of red-tailed tropicbirds (Phaethon rubricauda) nesting both downwind and upwind of the incineration site. We found no effect of chemical incineration on these tropicbird demographic parameters over the 8 years of our study. An additional 3 years of monitoring tropicbird demography will take place, post-incineration.

Evolution of the east-central San Jose del Cabo basin, Baja California Sur, Mexico

NASA Astrophysics Data System (ADS)

McTeague, M. S.; Umhoefer, P. J.; Schwennicke, T.; Ingle, J. C.; Cortes Martinez, M.

2006-12-01

The San Jose del Cabo basin at the southern tip of the Baja California peninsula records the early tectonic evolution of the west side of the Gulf of California. This study focused on the east central margin of the basin. The basal La Calera Formation unconformably overlies Cretaceous granite and consists of conglomerate, pebbly sandstone and conglomerate, and sandstone deposited in alluvial fans and fan-deltas. Deposition of the La Calera Formation was from ca. 9-14 Ma. The lower member of the Trinidad Formation was deposited beginning ca. 9-13 Ma and consists of sandstone, mudstone, and shelly mudstone deposited in nearshore and estuarine environments. These age estimates are based on sedimentation rates and foraminifera and coccoliths from the NN 11A nannozone (7.4 8.6 Ma, GTS 2004). The middle member of the Trinidad Formation consists of deeper water mudstones deposited by turbidity currents and suspension settling in a shelf to slope and conglomerates deposited by submarine debris flows on the shelf. The basin began earlier than previously thought. The oldest marine rocks are ca.9-13 Ma, while sedimentation on the east side began at ca. 9-14 Ma, synchronous with estimates of initiation of offset on the San Jose del Cabo fault. The Zapote fault is a down-to-the-east normal and sinistral-oblique fault that exposes a wedge of granite and older strata in the footwall to the west. The fault was active during sedimentation in the late Miocene and possibly later. The fault divides the study area into an eastern hanging wall subbasin and western footwall subbasin. The eastern subbasin formed an embayment in the eastern margin of the Cabo basin. A regional flooding surface (ca. 8 Ma) can be correlated across the fault that marks a major marine incursion. Depositional systems evolved rapidly from coarse-grained terrestrial systems to fine-grained marine and estuarine systems. The Cabo basin provides an excellent analogue for comparison with offshore basins, which are broadly similar with more faulting in lower strata and fewer or no faulting in upper strata. Offshore seismic data show older, deformed syn-rift strata in half graben overlain by younger, undeformed post-rift strata. The normal faults with 1-5 km spacing cut the basement rock and oldest sedimentary units. The eastern margin of the Cabo basin has older, growth strata cut by the Zapote fault that are overlain by simpler strata. Smaller scale normal faults in the Cabo basin are no longer active while the Cabo fault remains active.

Brittle Deformation in the Ordos Basin in response to the Mesozoic destruction of the North China Craton

NASA Astrophysics Data System (ADS)

Wang, Q.; Jiang, L.

2012-12-01

Craton is continental block that has been tectonically stable since at least Proterozoic. Some cratons, however, become unstable for some geodynamic reasons. The North China Craton (NCC) is an example. Structure geological, geochemical, and geophysical works have revealed that the NCC was destructed in Cretaceous and that lithosphere thickness beneath the eastern NCC were thinned by 120 km. The present study will focus on deformation of the western NCC, and to understand the effect of the Mesozoic destruction of the North China Craton (NCC). Structural partitioning of the Ordos Basin, which is located in the western NCC, from the eastern NCC occurred during the Mesozoic. Unlike the eastern NCC where many Cretaceous metamorphic core complexes developed, sedimentary cover of the NCC remains nearly horizontal and deformation is manifested by joint. We visited 216 sites of outcrops and got 1928 joints measurements, among which 270 from Jurassic sandstones, 1378 from the Upper Triassic sandstones, 124 from the Middle and Lower Triassic sandstones, and 156 from Paleozoic sandstones. In the interior of the Ordos Basin, joints developed quite well in the Triassic strata, while joints in the Jurassic stata developed weakly and no joint in the Cretaceous strata. The Mesozoic stratigraphic thickness are: 1000 meters for the Lower Triassic, the Middle Triassic sandstone with thickness of 800 meters, 3000 meters for the Upper Triassic, 4000 meters for the Jurassic, and 1100 meters for the Lower Cretaceous. The vertical difference in joint development might be related to the burying depth of the strata: the higher the strata, the smaller the lithostatic stress, and then the weaker the joint. Joints in all stratigraphic levels showed a similar strain direction with the sigma 1 (the maximum pressure stress) vertical and the sigma 3 (the minimum pressure stress) horizontal and running N-S. The unconformity below the Cretaceous further indicates that joints in Jurassic and Triassic strata were developed in the beginning of Cretaceous. It seems that the western NCC experienced only uplift that recorded a weak N-S extension and E-W compression during the Early Cretaceous when the NCC experienced destruction. Conclusions: 1. The Cretaceous uplift ceased the "natural test of mechanical property" of the strata in the Ordos Basin. The difference in burying depth of the strata caused the vertical difference in joints development. 2. Joints in the interior of the Ordos Basin indicate a N-S extension and E-W compression with the sigma 1 vertical in the Early Cretaceous, as implying a regional uplift in the western NCC during its Mesozoic destruction.

Three-Dimensional Structural and Hydrologic Evolution of Sant Corneli Anticline, a Fault-Cored Fold in the Central Spanish Pyrenees

NASA Astrophysics Data System (ADS)

Shackleton, J. R.; Cooke, M. L.

2005-12-01

The Sant Corneli Anticline is a well-exposed example of a fault-cored fold whose hydrologic evolution and structural development are directly linked. The E-W striking anticline is ~ 5 km wide with abrupt westerly plunge, and formed in response to thrusting associated with the upper Cretaceous to Miocene collision of Iberia with Europe. The fold's core of fractured carbonates contains a variety of west dipping normal faults with meter to decameter scale displacement and abundant calcite fill. This carbonate unit is capped by a marl unit with low angle, calcite filled normal faults. The marl unit is overlain by clastic syn-tectonic strata whose sedimentary architecture records limb rotation during the evolution of the fold. The syn-tectonic strata contain a variety of joint sets that record the stresses before, during, and possibly after fold growth. Faulting in the marl and calcite-filled joints in the syn-tectonic strata suggest that normal faults within the carbonate core of the fold eventually breached the overlying marl unit. This breach may have connected the joints of the syn-tectonic strata to the underlying carbonate reservoir and eliminated previous compartmentalization of fluids. Furthermore, breaching of the marl units probably enhanced joint formation in the overlying syn-tectonic strata. Future geochemical studies of calcite compositions in the three units will address this hypothesis. Preliminary mapping of joint sets in the syn-tectonic strata reveal a multistage history of jointing. Early bed-perpendicular joints healed by calcite strike NE-SW, parallel to normal faults in the underlying carbonates, and may be related to an early regional extensional event. Younger healed bed-perpendicular joints cross cut the NE-SW striking set, and are closer to N-S in strike: these joints are interpreted to represent the initial stages of folding. Decameter scale, bed perpendicular, unfilled fractures that are sub-parallel to strike probably represent small joints and faults that formed in response to outer arc extension during folding. Many filled, late stage joints strike sub-parallel to, and increase in frequency near, normal faults and transverse structures observed in the carbonate fold core. This suggests that faulting in the underlying carbonates and marls significantly affected the joint patterns in the syn-tectonic strata. Preliminary three-dimensional finite element restorations using Dynel have allowed us to test our hypotheses and constrain the timing of jointing and marl breach.

Polymeric nanoparticles-based topical delivery systems for the treatment of dermatological diseases

PubMed Central

Zhang, Zheng; Tsai, Pei-Chin; Ramezanli, Tannaz; Michniak-Kohn, Bozena B.

2013-01-01

Human skin not only functions as a permeation barrier (mainly due to the stratum corneum layer), but also provides a unique delivery pathway for therapeutic and other active agents. These compounds penetrate via intercellular, intracellular and transappendageal routes, resulting in topical delivery (into skin strata) and transdermal delivery (to subcutaneous tissues and into the systemic circulation). Passive and active permeation enhancement methods have been widely applied to increase the cutaneous penetration. The pathology, pathogenesis and topical treatment approaches of dermatological diseases, such as psoriasis, contact dermatitis, and skin cancer, are then discussed. Recent literature has demonstrated that nanoparticles-based topical delivery systems can be successful in treating these skin conditions. The studies are reviewed starting with the nanoparticles based on natural polymers specially chitosan, followed by those made of synthetic, degradable (aliphatic polyesters) and non-degradable (polyarylates) polymers; emphasis is given to nanospheres made of polymers derived from naturally occurring metabolites, the tyrosine-derived nanospheres (TyroSpheres™). In summary, the nanoparticles-based topical delivery systems combine the advantages of both the nano-sized drug carriers and the topical approach, and are promising for the treatment of skin diseases. For the perspectives, the penetration of ultra-small nanoparticles (size smaller than 40 nm) into skin strata, the targeted delivery of the encapsulated drugs to hair follicle stem cells, and the combination of nanoparticles and microneedle array technologies for special applications such as vaccine delivery are discussed. PMID:23386536

Development and validation of a solid-phase extraction method coupled to liquid chromatography with fluorescence detection for the determination of fluoroquinolone residues in powdered infant formulae. Application to the analysis of samples from the Spanish and Latin American market.

PubMed

Rodriguez, E; Moreno-Bondi, M C; Marazuela, M D

2008-10-31

This paper describes a new method for the effective extraction, clean-up and chromatographic analysis of residues of four fluoroquinolones (ciprofloxacin, enrofloxacin, danofloxacin and sarafloxacin) in powdered infant formulae and follow-on preparations. Samples were reconstituted following the manufacturer's recommendations and treated with trichloroacetic acid in methanol 10% (w/v) for deproteinization. Two solid-phase extraction cartridges have been evaluated for sample clean-up and preconcentration, Strata Screen A and Strata X and the later provided the best recoveries for all the analytes tested. Chromatographic analysis has been carried out using a polar endcapped column (AQUA C(18)) and fluorescence detection, with lomefloxacin (LOME) as internal standard. Method validation has been performed according to European Commission Decision 2002/657/EC criteria, in terms of linearity, recovery, precision, specificity, decision limit (CC(alpha)) and detection capability (CC(beta)). Typical recoveries ranged between 70 and 110% at levels below and above the maximum residue limits of the target analytes in bovine milk, with an excellent intralab reproducibility (RSDs<7%). Matrix effects did not significantly affect method accuracy, as evidenced by analyzing different brands of milk. The method has been successfully applied to the analysis of 100 samples of infant and follow-on formulae of the Spanish and Latin American market, using LC-MS/MS as confirmatory technique.

The role of Octenidol(®), Glandomed(®) and chlorhexidine mouthwash in the prevention of mucositis and in the reduction of the oropharyngeal flora: a double-blind randomized controlled trial.

PubMed

Mutters, Nico T; Neubert, Thomas R; Nieth, Rudolf; Mutters, Reinier

2015-01-01

The oropharyngeal flora is of importance for the development of oral mucositis, which is a frequent complication in oncologic practice. It also plays a role in the pathogenesis of ventilator-associated pneumonia. Mucositis is associated with significantly worse clinical and economic outcomes. The aim of our study was to assess the efficacy of Octenidol(®), Glandomed(®) and chlorhexidine mouthwash in the prevention of mucositis and reduction of the oropharyngeal flora. A prospective, double-blinded RCT including two strata was conducted between October 2008 and November 2010. Stratum i consisted of ventilated cardiothoracic surgical patients. Stratum ii consisted of medical patients with haemato-oncological malignancies requiring stem cell transplantation. The primary outcome measures were development of mucositis regarding to OMAS/WHO score and reduction of the oropharyngeal flora. Both strata showed low OMAS/WHO scores which did not differ significantly between the groups. The overall mean reduction of colony forming units was significantly higher in the Octenidol(®) group compared to the chlorhexidine and the Glandomed(®) groups. No significant differences in the development of mucositis were found, thus all solutions proved successful in the prevention of mucositis. However, Octenidol(®) was superior in the reduction of the oropharyngeal flora. Hence, the preventive effect on nosocomial infections might be higher in patients using Octenidol(®) rather than chlorhexidine or Glandomed(®).

Leaiid conchostracans from the uppermost Permian strata of the Paraná Basin, Brazil: Chronostratigraphic and paleobiogeographic implications

NASA Astrophysics Data System (ADS)

Ferreira-Oliveira, Luis Gustavo; Rohn, Rosemarie

2010-03-01

Conchostracan fossils are abundant and relatively diversified in the Rio do Rasto Formation (Passa Dois Group, Paraná Basin, southern Brazil), but leaiids (' Leaia pruvosti' [Reed, F.R.C., 1929. Novos Phyllopodos Fósseis do Brasil. Boletim do Serviço Geológico e Mineralógico do Brasil 34, 2-16]) were previously found at only one locality of the formation in the northern Santa Catarina State. New specimens of the Family Leaiidae, collected from two outcrops in central Paraná State near the top of the formation, stimulated a revision of related taxa. Both the new and the previously known leaiids are herein assigned to Hemicycloleaia mitchelli [Etheridge Jr., R., 1892. On Leaia mitchelli Etheridge. Proceedings of the Linnean Society of New South Wales 7, 307-310] based on the presence of three carinae and subovate shape. This species was originally recorded in the upper Tatarian (Wuchiapingian, Late Permian) of Sydney Basin, eastern Australia and therefore corroborates the interpretation that the leaiid bearing strata of the Rio do Rasto Formation cannot be younger than Permian. H. mitchelli possibly was one of the most widespread, eurytopic and conservative Late Paleozoic conchostracans of Gondwana (although records from Africa, India and Antarctica must still be confirmed) and it was also found in the Tatarian of Russia. The sudden disappearance of leaiids after their apparent success is consistent with the hypothesis about the biotic crisis around the Permo-Triassic boundary.

Stratigraphic Mapping of Intra-Crater Layered Deposits in Arabia Terra from High-Resolution Imaging and Stereo Topography

NASA Astrophysics Data System (ADS)

Annex, A. M.; Lewis, K. W.; Edwards, C. S.

2017-12-01

The Arabia Terra region of Mars, located in the mid-latitudes, hosts a number of crater basins with exposed sedimentary layers and buttes. Our work builds upon previous studies of these sites that suggest that the layers are formed of weakly lithified aeolian material with quasi-periodic expressions explained by changes in planetary orbital elements during formation (Lewis and Aharonson, 2014; Cadieux and Kah, 2015; Stack et al., 2013). In an effort to better understand differences in lateral continuity of these layers, both between and within basins, an extensive mapping effort was conducted on several sites in Arabia Terra with HiRISE stereo targets. Digital terrain models produced using the Ames Stereo Pipeline were mapped to derive bedding plane positions and orientations for each stratum using linear regression. Bed thicknesses were derived from differences in dip-corrected elevation between successive strata. Our study includes additional independent mapping within craters analyzed in previous studies, and expands mapping of these deposits to several new craters in the region unique to this effort. Our sample size in this study is large, including over 700 individually measured strata from multiple sections within each crater. Although bed thicknesses are generally tightly distributed around 12 meters, any changes within a sequence could represent variations in either the dominant forcing factors controlling deposition and/or changes in sedimentation rate. If craters contain correlative sequences, these types of changes could serve as marker horizons across the region with further mapping.

Hydrocarbon and Carbon Dioxide Fluxes from Natural Gas Well Pad Soils and Surrounding Soils in Eastern Utah.

PubMed

Lyman, Seth N; Watkins, Cody; Jones, Colleen P; Mansfield, Marc L; McKinley, Michael; Kenney, Donna; Evans, Jordan

2017-10-17

We measured fluxes of methane, nonmethane hydrocarbons, and carbon dioxide from natural gas well pad soils and from nearby undisturbed soils in eastern Utah. Methane fluxes varied from less than zero to more than 38 g m -2 h -1 . Fluxes from well pad soils were almost always greater than from undisturbed soils. Fluxes were greater from locations with higher concentrations of total combustible gas in soil and were inversely correlated with distance from well heads. Several lines of evidence show that the majority of emission fluxes (about 70%) were primarily due to subsurface sources of raw gas that migrated to the atmosphere, with the remainder likely caused primarily by re-emission of spilled liquid hydrocarbons. Total hydrocarbon fluxes during summer were only 39 (16, 97)% as high as during winter, likely because soil bacteria consumed the majority of hydrocarbons during summer months. We estimate that natural gas well pad soils account for 4.6 × 10 -4 (1.6 × 10 -4 , 1.6 × 10 -3 )% of total emissions of hydrocarbons from the oil and gas industry in Utah's Uinta Basin. Our undisturbed soil flux measurements were not adequate to quantify rates of natural hydrocarbon seepage in the Uinta Basin.

Persistence of Coastal Vegetation in Supratidal Zones of Northern China

PubMed Central

Yang, Hongxiao; Chu, Jianmin

2013-01-01

Coastal vegetation comprises a number of coastal specialists and terrestrial generalists. It remains unclear how they persist on disturbed and undisturbed coastal conditions. We tested the hypothesis that coastal specialists may be superior to terrestrial generalists on supratidal zones of coasts, but their superiority can be influenced by human disturbances. Eight separate sandy coasts of the Shandong Peninsula were sampled, representing for disturbed and undisturbed sandy coasts. Plants growing on their supratidal zones were surveyed. On this basis, we compared the relative dominances, niche widths, and commonness of all species, and also analyzed species diversities of the coasts. Coastal specialists were found to be more common and widespread on supratidal zones of the sandy coasts than terrestrial generalists haphazardly invading from hinterlands. Coastal specialists exhibited lower Sørensen dissimilarities than terrestrial generalists among the coasts. Tourist trampling seemed more detrimental than pond fishery to coastal vegetation. Relative to terrestrial generalists, coastal specialists responded to human disturbances more deterministically, with steady decreases in species diversities. These evidences verify that coastal specialists are intrinsically superior to terrestrial generalists on supratidal zones of coasts, especially of undisturbed coasts, because their dispersal among coasts adapts well to local storm surge regime. They also validate that human disturbances can depress the superiority of coastal specialists, partly by inducing invasion of terrestrial generalists. PMID:24224026

Low-level nocturnal wind maximum over the Central Amazon Basin

NASA Technical Reports Server (NTRS)

Greco, Steven; Ulanski, Stanley; Garstang, Michael; Houston, Samuel

1992-01-01

A low-level nocturnal wind maximum is shown to exist over extensive and nearly undisturbed rainforest near the central Amazon city of Manaus. Meteorological data indicate the presence of this nocturnal wind maximum during both the wet and dry seasons of the Central Amazon Basin. Daytime wind speeds which are characteristically 3-7 m/s between 300 and 1000 m increase to 10-15 m/s shortly after sunset. The wind-speed maximum is reached in the early evening, with wind speeds remaining high until several hours after sunrise. The nocturnal wind maximum is closely linked to a strong low-level inversion formed by radiational cooling of the rainforest canopy. Surface and low-level pressure gradients between the undisturbed forest and the large Amazon river system and the city of Manaus are shown to be responsible for much of the nocturnal wind increase. The pressure gradients are interpreted as a function of the thermal differences between undisturbed forest and the river/city. The importance of both the frictional decoupling and the horizontal pressure gradient suggest that the nocturnal wind maximum does not occur uniformly over all Amazonia. Low-level winds are thought to be pervasive under clear skies and strong surface cooling and that, in many places (i.e., near rivers), local pressure gradients enhance the low-level nocturnal winds.

Effect of soil disturbance on recharging fluxes: Case study on the Snake River Plain, Idaho National Laboratory, USA

USGS Publications Warehouse

Nimmo, J.R.; Perkins, K.S.

2008-01-01

Soil structural disturbance influences the downward flow of water that percolates deep enough to become aquifer recharge. Data from identical experiments in an undisturbed silt-loam soil and in an adjacent simulated waste trench composed of the same soil material, but disturbed, included (1) laboratory- and field-measured unsaturated hydraulic properties and (2) field-measured transient water content profiles through 24 h of ponded infiltration and 75 d of redistribution. In undisturbed soil, wetting fronts were highly diffuse above 2 m depth, and did not go much deeper than 2 m. Darcian analysis suggests an average recharge rate less than 2 mm/year. In disturbed soil, wetting fronts were sharp and initial infiltration slower; water moved slowly below 2 m without obvious impediment. Richards' equation simulations with realistic conditions predicted sharp wetting fronts, as observed for disturbed soil. Such simulations were adequate for undisturbed soil only if started from a post-initial moisture distribution that included about 3 h of infiltration. These late-started simulations remained good, however, through the 76 d of data. Overall results suggest the net effect of soil disturbance, although it reduces preferential flow, may be to increase recharge by disrupting layer contrasts. ?? Springer-Verlag 2007.

Seed banks in a degraded desert shrubland: Influence of soil surface condition and harvester ant activity on seed abundance

USGS Publications Warehouse

DeFalco, L.A.; Esque, T.C.; Kane, J.M.; Nicklas, M.B.

2009-01-01

We compared seed banks between two contrasting anthropogenic surface disturbances (compacted, trenched) and adjacent undisturbed controls to determine whether site condition influences viable seed densities of perennial and annual Mojave Desert species. Viable seeds of perennials were rare in undisturbed areas (3-4 seeds/m2) and declined to <1 seed/m2 within disturbed sites. Annual seed densities were an order of magnitude greater than those of perennials, were one-third the undisturbed seed densities on compacted sites, but doubled on trenched sites relative to controls. On trenched sites, greater litter cover comprising the infructescences of the dominant spring annuals, and low gravel content, enhanced seed densities of both annuals and perennials. Litter cover and surface ruggedness were the best explanations for viable perennial seed densities on compacted sites, but litter cover and the presence of a common harvester ant explained annual seed densities better than any other surface characteristics that were examined. Surface disturbances can have a varied impact on the condition of the soil surface in arid lands. Nevertheless, the consistently positive relationship between ground cover of litter and viable seed density emphasizes the importance of litter as an indicator of site degradation and recovery potential in arid lands.

A correction procedure for thermally two-way coupled point-particles

NASA Astrophysics Data System (ADS)

Horwitz, Jeremy; Ganguli, Swetava; Mani, Ali; Lele, Sanjiva

2017-11-01

Development of a robust procedure for the simulation of two-way coupled particle-laden flows remains a challenge. Such systems are characterized by O(1) or greater mass of particles relative to the fluid. The coupling of fluid and particle motion via a drag model means the undisturbed fluid velocity evaluated at the particle location (which is needed in the drag model) is no longer equal to the interpolated fluid velocity at the particle location. The same issue arises in problems of dispersed flows in the presence of heat transfer. The heat transfer rate to each particle depends on the difference between the particle's temperature and the undisturbed fluid temperature. We borrow ideas from the correction scheme we have developed for particle-fluid momentum coupling by developing a procedure to estimate the undisturbed fluid temperature given the disturbed temperature field created by a point-particle. The procedure is verified for the case of a particle settling under gravity and subject to radiation. The procedure is developed in the low Peclet, low Boussinesq number limit, but we will discuss the applicability of the same correction procedure outside of this regime when augmented by appropriate drag and heat exchange correlations. Supported by DOE, J. H. Supported by NSF GRF

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

Rockaway, J.D.; Stephenson, R.W.

The study described was accomplished through an investigation of both the intact and insitu geotechnical properties of the subcoal strata and through the installation of floor movement monitoring instrumentation. The method of bearing capacity analysis developed by A.S. Vesic was used to define pillar stability. This method includes provisions for taking into consideration a two-layer system such as assumed for mine conditions where a weak underclay overlies firmer strata. 4 refs.

Assessment of undiscovered oil and gas resources in Jurassic and Cretaceous strata of the Gulf Coast, 2010

USGS Publications Warehouse

Dubiel, Russell F.; Warwick, Peter D.; Swanson, Sharon; Burke, Lauri; Biewick, Laura; Charpentier, Ronald R.; Coleman, James L.; Cook, Troy A.; Dennen, Kris; Doolan, Colin A.; Enomoto, Catherine; Hackley, Paul C.; Karlsen, Alexander W.; Klett, Timothy R.; Kinney, Scott A.; Lewan, Michael D.; Merrill, Matt; Pearson, Krystal; Pearson, Ofori N.; Pitman, Janet K.; Pollastro, Richard M.; Rowan, Elizabeth L.; Schenk, Christopher J.; Valentine, Brett

2011-01-01

Using a geology-based assessment methodology, the U.S. Geological Survey estimated means of 147.4 trillion cubic feet of undiscovered natural gas, 2.4 billion barrels of undiscovered oil, and 2.96 billion barrels of undiscovered natural gas liquids in Jurassic and Cretaceous strata in onshore lands and State waters of the Gulf Coast.

Coupling Aeolian Stratigraphic Architecture to Paleo-Boundary Conditions: The Scour-Fill Dominated Jurassic Page Sandstone

NASA Astrophysics Data System (ADS)

Cardenas, B. T.; Kocurek, G.; Mohrig, D. C.; Swanson, T.

2017-12-01

The stratigraphic architecture of aeolian sandstones is thought to encode signals originating from both autogenic dune behavior and allogenic boundary conditions within which the dune field evolves. Mapping of outcrop-scale bounding surfaces and sets of cross-strata between these surfaces for the Jurassic Page Sandstone near Page, AZ, USA, demonstrates that dune autogenic behavior manifested in variable dune scour depth, whereas the dominant boundary conditions were antecedent topography and water-table elevation. At the study area, the Page Sandstone is 60 m thick and is separated from the underlying Navajo Sandstone by the J-2 regional unconformity, which shows meters of relief. Filling J-2 depressions are thin, climbing sets of cross-strata. In contrast, the overlying Page consists of packages of one to a few, meter-scale sets of cross-strata between the outcrop-scale bounding surfaces. These surfaces, marked by polygonal fractures and local overlying sabkha deposits, are regional in scale and correlated to high stands of the adjacent Carmel sea. Over the km-scale outcrop, the surfaces show erosional relief and packages of cross-strata are locally truncated. Notably absent within these cross-strata packages are early dune-field accumulations, interdune deposits, and apparent dune-climbing. These strata are interpreted to represent a scour-fill architecture created by migrating large dunes within a mature dry aeolian sand sea, in which early phases of dune-field construction have been cannibalized and dune fill of the deepest scours is recorded. At low angles of climb, set thickness is dominated by the component of scour-depth variation over the component resulting from the angle of climb. After filling of J-2 depressions, the Page consists of scour-fill accumulations formed during low stands. Carmel transgressions limited sediment availability, causing deflation to the water table and development of the regional bounding surfaces. Each subsequent fall of the water table with Carmel regressions renewed sediment availability, including local breaching of the resistant surfaces and cannibalization of Page accumulations. The Page record exists because of preservation associated with Carmel transgressions and subsidence, without which the Page would be represented by an erosional surface.

Inference of strata separation and gas emission paths in longwall overburden using continuous wavelet transform of well logs and geostatistical simulation

NASA Astrophysics Data System (ADS)

Karacan, C. Özgen; Olea, Ricardo A.

2014-06-01

Prediction of potential methane emission pathways from various sources into active mine workings or sealed gobs from longwall overburden is important for controlling methane and for improving mining safety. The aim of this paper is to infer strata separation intervals and thus gas emission pathways from standard well log data. The proposed technique was applied to well logs acquired through the Mary Lee/Blue Creek coal seam of the Upper Pottsville Formation in the Black Warrior Basin, Alabama, using well logs from a series of boreholes aligned along a nearly linear profile. For this purpose, continuous wavelet transform (CWT) of digitized gamma well logs was performed by using Mexican hat and Morlet, as the mother wavelets, to identify potential discontinuities in the signal. Pointwise Hölder exponents (PHE) of gamma logs were also computed using the generalized quadratic variations (GQV) method to identify the location and strength of singularities of well log signals as a complementary analysis. PHEs and wavelet coefficients were analyzed to find the locations of singularities along the logs. Using the well logs in this study, locations of predicted singularities were used as indicators in single normal equation simulation (SNESIM) to generate equi-probable realizations of potential strata separation intervals. Horizontal and vertical variograms of realizations were then analyzed and compared with those of indicator data and training image (TI) data using the Kruskal-Wallis test. A sum of squared differences was employed to select the most probable realization representing the locations of potential strata separations and methane flow paths. Results indicated that singularities located in well log signals reliably correlated with strata transitions or discontinuities within the strata. Geostatistical simulation of these discontinuities provided information about the location and extents of the continuous channels that may form during mining. If there is a gas source within their zone of influence, paths may develop and allow methane movement towards sealed or active gobs under pressure differentials. Knowledge gained from this research will better prepare mine operations for potential methane inflows, thus improving mine safety.

Tectonic controls on deposition of Middle Jurassic strata in a retroarc foreland basin, Utah-Idaho trough, western interior, United States

NASA Astrophysics Data System (ADS)

Bjerrum, Christian J.; Dorsey, Rebecca J.

1995-08-01

An electronic supplement of this material may be obtained on a diskette or Anonymous FTP from KOSMOS.AGU.ORG. (LOGIN to AGU's FTP account using ANONYMOUS as the username and GUEST as the password. Go to the right directory by typing CD APEND. Type LS to see what files are available. Type GET and the name of the file to get it. Finally, type EXIT to leave the system.) (Paper 95TC01448, Tectonic controls on deposition of Middle Jurassic strata in a retroarc foreland basin, Utah-Idaho trough, western interior, United States, Christian J. Bjerrum and Rebecca J. Dorsey). Diskette may be ordered from American Geophysical Union, 2000 Florida Avenue, N. W., Washington, DC 20009; $15.00. Payment must accompany order. A thick succession of Jurassic nonmarine and marine sedimentary rocks is exposed in a large area from northern Arizona to eastern Idaho and western Wyoming. These sediments accumulated in the Utah-Idaho trough, a deep elongate cratonal basin whose origin has recently been debated. Detailed stratigraphic analysis, subsidence analysis, and first-order flexural modeling of these deposits (this study) provide new insights into the timing and mechanisms of subsidence in the Utah-Idaho trough. Lower and Middle Jurassic strata are divided into six unconformity-bounded sequences. In contrast to the overall uniform thickness of Lower Jurassic sequences (1 and 2), Middle Jurassic strata (sequences 3 through 6) consist of distinctly westward thickening sedimentary packages in which basal shallow marine deposits onlap eastward onto bounding unconformities. Basal strata of sequences 3 through 6 pass upward into widespread progradational continental deposits that are truncated progressively toward the east (cratonward) by the next unconformity. Decompacted total subsidence curves show that the rate of subsidence in most sections increased sharply at the end of sequence 2 time (J-2 unconformity; ˜170 Ma). This is interpreted to record the onset of Middle Jurassic deposition in the distal part of a retroarc foreland basin. The unconformities and distinctive stratal geometries may have formed in response to forebulge migration caused by episodic thrusting in the Cordilleran orogen to the west. First-order flexural modeling was carried out to test the hypothesis of flexural subsidence in the Utah-Idaho trough. Trial-and-error comparisons produce a close match between decompacted stratigraphic profiles and model deflection profiles. The best fit is obtained using an infinite elastic plate (D = 1 × 1024 Nm), a moderate load topography, elevated base level, and an overfilled basin. Using recently published tectonic reconstructions for Nevada and Utah, we find close spatial agreement between a large Middle Jurassic fold-thrust belt and the supracrustal load inferred from model simulations. Our integrated basin analysis thus supports the interpretation of some previous studies that the Middle Jurassic Utah-Idaho trough was a retroarc foreland basin that formed east of a belt of regional contractile deformation and crustal thickening in western and central Nevada and southeastern California. Late Jurassic extension and normal faulting in northeastern Nevada may have been related to gravitational collapse of overthickened crust in the Cordilleran orogen. This coincides with a period of slowed subsidence in the Utah-Idaho trough that began at about 157 Ma.

Contributions of human activities to suspended sediment yield during storm events from a small, steep, tropical watershed

NASA Astrophysics Data System (ADS)

Messina, A. M.; Biggs, T. W.

2016-07-01

Suspended sediment concentrations (SSC) and yields (SSY) were measured during storm and non-storm periods from undisturbed and human-disturbed portions of a small (1.8 km2), mountainous watershed that drains to a sediment-stressed coral reef. Event-wise SSY (SSYEV) was calculated for 142 storms from measurements of water discharge (Q), turbidity (T), and SSC measured downstream of three key sediment sources: undisturbed forest, an aggregate quarry, and a village. SSC and SSYEV were significantly higher downstream of the quarry during both storm- and non-storm periods. The human-disturbed subwatershed (10.1% disturbed) accounted for an average of 87% of SSYEV from the watershed. Observed sediment yield (mass) to the coast, including human disturbed subwatersheds, was 3.9× the natural background. Specific SSY (mass/area) from the disturbed quarry area was 49× higher than from natural forest compared with 8× higher from the village area. Similar to mountainous watersheds in semi-arid and temperate climates, SSYEV from both the undisturbed and disturbed watersheds correlated closely with maximum event discharge (Qmax), event total precipitation and event total Q, but not with the Erosivity Index. Best estimates of annual SSY varied by method, from 45 to 143 tons/km2/yr from the undisturbed subwatershed, 441-598 tons/km2/yr from the human-disturbed subwatershed, and 241-368 tons/km2/yr from the total watershed. Sediment yield was very sensitive to disturbance; the quarry covers 1.1% of the total watershed area, but contributed 36% of SSYEV. Given the limited access to gravel for infrastructure development, sediment disturbance from local aggregate mining may be a critical sediment source on remote islands in the Pacific and elsewhere. Identification of erosion hotspots like the quarry using rapid, event-wise measures of suspended sediment yield will help efforts to mitigate sediment stress and restore coral reefs.

Effects of dam-induced landscape fragmentation on amazonian ant-plant mutualistic networks.

PubMed

Emer, Carine; Venticinque, Eduardo Martins; Fonseca, Carlos Roberto

2013-08-01

Mutualistic networks are critical to biological diversity maintenance; however, their structures and functionality may be threatened by a swiftly changing world. In the Amazon, the increasing number of dams poses a large threat to biological diversity because they greatly alter and fragment the surrounding landscape. Tight coevolutionary interactions typical of tropical forests, such as the ant-myrmecophyte mutualism, where the myrmecophyte plants provide domatia nesting space to their symbiotic ants, may be jeopardized by the landscape changes caused by dams. We analyzed 31 ant-myrmecophyte mutualistic networks in undisturbed and disturbed sites surrounding Balbina, the largest Central Amazonian dam. We tested how ant-myrmecophyte networks differ among dam-induced islands, lake edges, and undisturbed forests in terms of species richness, composition, structure, and robustness (number of species remaining in the network after partner extinctions). We also tested how landscape configuration in terms of area, isolation, shape, and neighborhood alters the structure of the ant-myrmecophyte networks on islands. Ant-myrmecophytic networks were highly compartmentalized in undisturbed forests, and the compartments had few strongly connected mutualistic partners. In contrast, networks at lake edges and on islands were not compartmentalized and were negatively affected by island area and isolation in terms of species richness, density, and composition. Habitat loss and fragmentation led to coextinction cascades that contributed to the elimination of entire ant-plant compartments. Furthermore, many myrmecophytic plants in disturbed sites lost their mutualistic ant partners or were colonized by opportunistic, nonspecialized ants. Robustness of ant-myrmecophyte networks on islands was lower than robustness near lake edges and in undisturbed forest and was particularly susceptible to the extinction of plants. Beyond the immediate habitat loss caused by the building of large dams in Amazonia, persistent edge effects and habitat fragmentation associated with dams had large negative effects on animal-plant mutualistic networks. © 2013 Society for Conservation Biology.

Genetic and epigenetic divergence between disturbed and undisturbed subpopulations of a Mediterranean shrub: a 20-year field experiment.

PubMed

Herrera, Carlos M; Bazaga, Pilar

2016-06-01

Little is known on the potential of ecological disturbance to cause genetic and epigenetic changes in plant populations. We take advantage of a long-term field experiment initiated in 1986 to study the demography of the shrub Lavandula latifolia , and compare genetic and epigenetic characteristics of plants in two adjacent subplots, one experimentally disturbed and one left undisturbed, 20 years after disturbance. Experimental setup was comparable to an unreplicated 'Before-After-Control-Impact' (BACI) design where a single pair of perturbed and control areas were compared. When sampled in 2005, plants in the two subplots had roughly similar ages, but they had established in contrasting environments: dense conspecific population ('Undisturbed' subpopulation) versus open area with all conspecifics removed ('Disturbed' subpopulation). Plants were characterized genetically and epigenetically using amplified fragment length polymorphism (AFLP) and two classes of methylation-sensitive AFLP (MSAP) markers. Subpopulations were similar in genetic diversity but differed in epigenetic diversity and multilocus genetic and epigenetic characteristics. Epigenetic divergence between subpopulations was statistically unrelated to genetic divergence. Bayesian clustering revealed an abrupt linear boundary between subpopulations closely coincident with the arbitrary demarcation line between subplots drawn 20 years back, which supports that genetic and epigenetic divergence between subpopulations was caused by artificial disturbance. There was significant fine-scale spatial structuring of MSAP markers in both subpopulations, which in the Undisturbed one was indistinguishable from that of AFLP markers. Genetic differences between subpopulations could be explained by divergent selection alone, while the concerted action of divergent selection and disturbance-driven appearance of new methylation variants in the Disturbed subpopulation is proposed to explain epigenetic differences. This study provides the first empirical evidence to date suggesting that relatively mild disturbances could leave genetic and epigenetic signatures on the next adult generation of long-lived plants.

The Seno Otway pockmark field and its relationship to thermogenic gas occurrence at the western margin of the Magallanes Basin (Chile)

NASA Astrophysics Data System (ADS)

Kilian, R.; Breuer, S.; Behrmann, J. H.; Baeza, O.; Diaz-Michelena, M.; Mutschke, E.; Arz, H.; Lamy, F.

2017-12-01

Pockmarks are variably sized crater-like structures that occur in young continental margin sediments. They are formed by gas eruptions and/or long-term release of fluid or gas. So far no pockmarks were known from the Pacific coast of South America between 51°S and 55°S. This article documents an extensive and previously unknown pockmark field in the Seno Otway (Otway Sound, 52°S) with multibeam bathymetry and parametric echosounding as well as sediment drill cores. Up to 31 pockmarks per square kilometer occur in water depths of 50 to >100 m in late glacial and Holocene sediments. They are up to 150 m wide and 10 m deep. Below and near the pockmarks, echosounder profiles image acoustic blanking as well as gas chimneys often crosscutting the 20 to >30 m thick glacial sediments above the acoustic basement, in particular along fault zones. Upward-migrating gas is trapped within the sediment strata, forming dome-like features. Two 5 m long piston cores from inside and outside a typical pockmark give no evidence for gas storage within the uppermost sediments. The inside core recovered poorly sorted glacial sediment, indicating reworking and re-deposition after several explosive events. The outside core documents an undisturbed stratigraphic sequence since 15 ka. Many buried paleo-pockmarks occur directly below a prominent seismic reflector marking the mega-outflow event of the Seno Otway at 14.3 ka, lowering the proglacial lake level by about 80 m. This decompression would have led to frequent eruptions of gas trapped in reservoirs below the glacial sediments. However, the sediment fill of pockmarks formed after this event suggests recurrent events throughout the Holocene until today. Most pockmarks occur above folded hydrocarbon-bearing Upper Cretaceous and Paleogene rocks near the western margin of the Magallanes Basin, constraining them as likely source rocks for thermogenic gas.

Evolution of crystalline target rocks and impactites in the chesapeake bay impact structure, ICDP-USGS eyreville B core

USGS Publications Warehouse

Horton, J. Wright; Kunk, Michael J.; Belkin, Harvey E.; Aleinikoff, John N.; Jackson, John C.; Chou, I.-Ming

2009-01-01

The 1766-m-deep Eyreville B core from the late Eocene Chesapeake Bay impact structure includes, in ascending order, a lower basement-derived section of schist and pegmatitic granite with impact breccia dikes, polymict impact breccias, and cataclas tic gneiss blocks overlain by suevites and clast-rich impact melt rocks, sand with an amphibolite block and lithic boulders, and a 275-m-thick granite slab overlain by crater-fill sediments and postimpact strata. Graphite-rich cataclasite marks a detachment fault atop the lower basement-derived section. Overlying impactites consist mainly of basement-derived clasts and impact melt particles, and coastal-plain sediment clasts are underrepresented. Shocked quartz is common, and coesite and reidite are confirmed by Raman spectra. Silicate glasses have textures indicating immiscible melts at quench, and they are partly altered to smectite. Chrome spinel, baddeleyite, and corundum in silicate glass indicate high-temperature crystallization under silica undersaturation. Clast-rich impact melt rocks contain α-cristobalite and monoclinic tridymite. The impactites record an upward transition from slumped ground surge to melt-rich fallback from the ejecta plume. Basement-derived rocks include amphibolite-facies schists, greenschist(?)-facies quartz-feldspar gneiss blocks and subgreenschist-facies shale and siltstone clasts in polymict impact breccias, the amphibolite block, and the granite slab. The granite slab, underlying sand, and amphibolite block represent rock avalanches from inward collapse of unshocked bedrock around the transient crater rim. Gneissic and massive granites in the slab yield U-Pb sensitive high-resolution ion microprobe (SHRIMP) zircon dates of 615 ± 7 Ma and 254 ± 3 Ma, respectively. Postimpact heating was <~350 °C in the lower basement-derived section based on undisturbed 40Ar/39Ar plateau ages of muscovite and <~150 °C in sand above the suevite based on 40Ar/39Ar age spectra of detrital microcline.

Soft-sediment deformation in a tectonically active area: The Plio-Pleistocene Zarzal Formation in the Cauca Valley (Western Colombia)

NASA Astrophysics Data System (ADS)

Neuwerth, Ralph; Suter, Fiore; Guzman, Carlos A.; Gorin, Georges E.

2006-04-01

The Plio-Pleistocene Zarzal Formation corresponds to fluvio-lacustrine sediments deposited in an intramontane depression within the Colombian Andes, associated with the Cauca-Romeral Fault System. It crops out mainly in the Cauca Valley where numerous field sections have permitted the mapping of the vertical and lateral lithological variations. Lacustrine deposits of sands, silts, clays and diatomites are interbedded with fluvial sand and gravel beds and fluvio-volcanic mass flows derived from the volcanic Central Cordillera. Numerous soft-sediment deformation structures are encountered in this formation, particularly in fine- to medium-grained sands, silts and clays: load structures (load casts, flame structures, pseudonodules), water escape structures (water escape cusps, dish-and-pillar and pocket-and-pillar structures), soft-sediment intrusions (clastic sills and dykes), disturbed laminites, convolute laminations, slumps and synsedimentary faulting. Deformation mechanisms and driving forces are related essentially to gravitational instabilities, dewatering, liquidization and brittle deformations. Field and regional geological data show that most of these deformations are related to seismicity and can be interpreted as seismites. This area has a geological and recent seismic history and outcrops show both syn- and post-depositional faulting related to the transpressional regime of this part of the Colombian Andes, which generates strike-slip faults and associated local normal faults. The drainage pattern within the Zarzal Formation shows the signature of neotectonics. Moreover, the fine to coarse-grained sands of the Zarzal Formation are lithologies prone to liquefaction when affected by seismic waves. The intercalation of the deformed intervals within undisturbed strata confirms the catastrophic nature of the events. Finally, the large areal extent of the deformations and the type of structures are compatible with seismites. Consequently, the existence of seismites in the Zarzal Formation represents corroboration of tectonic activity in this area during the Pleistocene. Earthquakes with a magnitude higher than 5 can be postulated, based upon the proximity of active faults and the types of deformations.

The Seno Otway pockmark field and its relationship to thermogenic gas occurrence at the western margin of the Magallanes Basin (Chile)

NASA Astrophysics Data System (ADS)

Kilian, R.; Breuer, S.; Behrmann, J. H.; Baeza, O.; Diaz-Michelena, M.; Mutschke, E.; Arz, H.; Lamy, F.

2018-06-01

Pockmarks are variably sized crater-like structures that occur in young continental margin sediments. They are formed by gas eruptions and/or long-term release of fluid or gas. So far no pockmarks were known from the Pacific coast of South America between 51°S and 55°S. This article documents an extensive and previously unknown pockmark field in the Seno Otway (Otway Sound, 52°S) with multibeam bathymetry and parametric echosounding as well as sediment drill cores. Up to 31 pockmarks per square kilometer occur in water depths of 50 to >100 m in late glacial and Holocene sediments. They are up to 150 m wide and 10 m deep. Below and near the pockmarks, echosounder profiles image acoustic blanking as well as gas chimneys often crosscutting the 20 to >30 m thick glacial sediments above the acoustic basement, in particular along fault zones. Upward-migrating gas is trapped within the sediment strata, forming dome-like features. Two 5 m long piston cores from inside and outside a typical pockmark give no evidence for gas storage within the uppermost sediments. The inside core recovered poorly sorted glacial sediment, indicating reworking and re-deposition after several explosive events. The outside core documents an undisturbed stratigraphic sequence since 15 ka. Many buried paleo-pockmarks occur directly below a prominent seismic reflector marking the mega-outflow event of the Seno Otway at 14.3 ka, lowering the proglacial lake level by about 80 m. This decompression would have led to frequent eruptions of gas trapped in reservoirs below the glacial sediments. However, the sediment fill of pockmarks formed after this event suggests recurrent events throughout the Holocene until today. Most pockmarks occur above folded hydrocarbon-bearing Upper Cretaceous and Paleogene rocks near the western margin of the Magallanes Basin, constraining them as likely source rocks for thermogenic gas.

Reconnaissance stratigraphic studies in the Susitna basin, Alaska, during the 2014 field season

USGS Publications Warehouse

LePain, David L.; Stanley, Richard G.; Harun, Nina T.; Helmold, Kenneth P.; Tsigonis, Rebekah

2015-01-01

The Susitna basin is a poorly-understood Cenozoic successor basin immediately north of Cook Inlet in south-central Alaska (Kirschner, 1994). The basin is bounded by the Castle Mountain fault and Cook Inlet basin on the south, the Talkeetna Mountains on the east, the Alaska Range on the north, and the Alaska–Aleutian Range on the west (fig. 2-1). The Cenozoic fill of the basin includes coal-bearing nonmarine rocks that are partly correlative with Paleogene strata in the Matanuska Valley and Paleogene and Neogene formations in Cook Inlet (Stanley and others, 2013, 2014). Mesozoic sedimentary rocks are present in widely-scattered uplifts in and around the margins of the basin; these rocks differ significantly from Mesozoic rocks in the forearc basin to the south. Mesozoic strata in the Susitna region were likely part of a remnant ocean basin that preceded the nonmarine Cenozoic basin (Trop and Ridgway, 2007). The presence of coal-bearing strata similar to units that are proven source rocks for microbial gas in Cook Inlet (Claypool and others, 1980) suggests the possibility of a similar system in the Susitna basin (Decker and others, 2012). In 2011 the Alaska Division of Geological & Geophysical Surveys (DGGS) and Alaska Division of Oil and Gas, in collaboration with the U.S. Geological Survey, initiated a study of the gas potential of the Susitna basin (Gillis and others, 2013). This report presents a preliminary summary of the results from 14 days of helicopter-supported field work completed in the basin in August 2014. The goals of this work were to continue the reconnaissance stratigraphic work begun in 2011 aimed at understanding reservoir and seal potential of Tertiary strata, characterize the gas source potential of coals, and examine Mesozoic strata for source and reservoir potential

Modeling annual mallard production in the prairie-parkland region

USGS Publications Warehouse

Miller, M.W.

2000-01-01

Biologists have proposed several environmental factors that might influence production of mallards (Anas platyrhynchos) nesting in the prairie-parkland region of the United States and Canada. These factors include precipitation, cold spring temperatures, wetland abundance, and upland breeding habitat. I used long-term historical data sets of climate, wetland numbers, agricultural land use, and size of breeding mallard populations in multiple regression analyses to model annual indices of mallard production. Models were constructed at 2 scales: a continental scale that encompassed most of the mid-continental breeding range of mallards and a stratum-level scale that included 23 portions of that same breeding range. The production index at the continental scale was the estimated age ratio of mid-continental mallards in early fall; at the stratum scale my production index was the estimated number of broods of all duck species within an aerial survey stratum. Size of breeding mallard populations in May, and pond numbers in May and July, best modeled production at the continental scale. Variables that best modeled production at the stratum scale differed by region. Crop variables tended to appear more in models for western Canadian strata; pond variables predominated in models for United States strata; and spring temperature and pond variables dominated models for eastern Canadian strata. An index of cold spring temperatures appeared in 4 of 6 models for aspen parkland strata, and in only 1 of 11 models for strata dominated by prairie. Stratum-level models suggest that regional factors influencing mallard production are not evident at a larger scale. Testing these potential factors in a manipulative fashion would improve our understanding of mallard population dynamics, improving our ability to manage the mid-continental mallard population.

Overpressure and hydrocarbon accumulations in Tertiary strata, Gulf Coast of Louisiana

USGS Publications Warehouse

Nelson, Philip H.

2012-01-01

Many oil and gas reservoirs in Tertiary strata of southern Louisiana are located close to the interface between a sand-rich, normally pressured sequence and an underlying sand-poor, overpressured sequence. This association, recognized for many years by Gulf Coast explorationists, is revisited here because of its relevance to an assessment of undiscovered oil and gas potential in the Gulf Coast of Louisiana. The transition from normally pressured to highly overpressured sediments is documented by converting mud weights to pressure, plotting all pressure data from an individual field as a function of depth, and selecting a top and base of the pressure transition zone. Vertical extents of pressure transition zones in 34 fields across southern onshore Louisiana range from 300 to 9000 ft and are greatest in younger strata and in the larger fields. Display of pressure transition zones on geologic cross sections illustrates the relative independence of the depth of the pressure transition zone and geologic age. Comparison of the depth distribution of pressure transition zones with production intervals confirms previous findings that production intervals generally overlap the pressure transition zone in depth and that the median production depth lies above the base of the pressure transition zone in most fields. However, in 11 of 55 fields with deep drilling, substantial amounts of oil and gas have been produced from depths deeper than 2000 ft below the base of the pressure transition zone. Mud-weight data in 7 fields show that "local" pressure gradients range from 0.91 to 1.26 psi/ft below the base of the pressure transition zone. Pressure gradients are higher and computed effective stress gradients are negative in younger strata in coastal areas, indicating that a greater potential for fluid and sediment movement exists there than in older Tertiary strata.

Tectonic setting of the Taubaté Basin (Southeastern Brazil): Insights from regional seismic profiles and outcrop data

NASA Astrophysics Data System (ADS)

Cogné, Nathan; Cobbold, Peter R.; Riccomini, Claudio; Gallagher, Kerry

2013-03-01

In southeastern Brazil, a series of onshore Tertiary basins provides good evidence for post-rift tectonic activity. So as better to constrain their tectonic setting, we have revisited outcrops in the Taubaté and Resende basins and have reinterpreted 11 seismic profiles of the Taubaté Basin. Where Eocene to Oligocene strata crop out, syn-sedimentary faults are common and their senses of slip are mainly normal. In contrast, for two outcrops in particular, where syn-sedimentary faults have put Precambrian crystalline basement against Eocene strata, senses of slip are strongly left-lateral, as well as normal. Thus we distinguish between thin-skinned and thick-skinned faulting. Furthermore, at four outcrops, Precambrian basement has overthrust Tertiary or Quaternary strata. On the seismic profiles, basal strata onlap basement highs. Structures and stratigraphic relationships are not typical of a rift basin. Although normal faults are common, they tend to be steeply dipping, their stratigraphic offsets are small (tens of metres) and the faults do not bound large stratigraphic wedges or tilted blocks. At the edges of the basin, Eocene or Oligocene strata dip basinward, have been subject to exhumation, and in places form gentle anticlines, so that we infer post-Oligocene inversion. We conclude that, after an earlier phase of deformation, probably during the Late Cretaceous, the Taubaté Basin formed under left-lateral transtension during the Palaeogene, but was subject to right-lateral transpression during the Neogene. Thus the principal directions of stress varied in time. Because they did so consistently with those of the adjacent regions, as well as those of the Incaic and Quechua phases of Andean orogeny, we argue that the Tertiary basins of southeast Brazil have resulted from reactivation of Precambrian shear zones under plate-wide stress.

Dust Emissions from Undisturbed and Disturbed, Crusted Playa Surfaces: Cattle Trampling Effect

NASA Astrophysics Data System (ADS)

Zobeck, T. M.; Baddock, M. C.; van Pelt, R.; Fredrickson, E. L.

2009-12-01

Dry playa lake beds can be a significant source of fine dust emissions during high wind events in arid and semiarid landscapes. The physical and chemical properties of the playa surface control the amount and properties of the dust emitted. In this study, we use a field wind tunnel to quantify the dust emissions from a bare, fine-textured playa surface located in the Chihuahua Desert at the Jornada Experimental Range, near Las Cruces, New Mexico, USA. We tested natural, undisturbed crusted surfaces and surfaces that had been subjected to two levels of domestic animal disturbance. The animal disturbance was provided by trampling produced from one and ten passes along the length of the wind tunnel by a 630 kg Angus-Hereford cross cow. The trampling broke the durable crust and created loose erodible material. Each treatment (natural crust, one pass, and ten passes) was replicated three times. A push-type wind tunnel with a 6 m long, 0.5 m wide, and 1 m high test section was used to generate dust emissions under controlled conditions. Clean medium sand was dropped onto the playa surface to act as an abrader material. The tunnel wind speed was equivalent to 15 m/s at a height of 2 m over a smooth soil surface. The tunnel was initially run for ten minutes, with no abrader added. A second 30 minute run was subsequently sampled as abrader was added to the wind stream. Dust and saltating material were collected using an isokinetic slot sampler at the end of the tunnel. Total airborne dust was collected on two 25 cm x 20 cm glass fiber filters (GFF) and measured using a GRIMM particle monitor every 6 sec throughout each test run. Disturbance by trampling generated increased saltating material and airborne dust. The amount of saltating material measured during the initial (no abrader added) run was approximately 70% greater and 5.8 times the amount of saltating material measured on the one pass and ten pass plots, respectively, compared with that observed on the undisturbed plots. The total amount of dust measured during the initial (no abrader added) run on GFF for the one pass and ten pass plots was almost twice and three times, respectively, that observed on the undisturbed plots. The ten pass treatment generated about 75% more PM10 dust, as measured by the GRIMM particle monitor, than the undisturbed plots during the 30 minute abrader run.

The I.A.G. / A.I.G. SEDIBUD Book Project: Source-to-Sink Fluxes in Undisturbed Cold Environments

NASA Astrophysics Data System (ADS)

Beylich, Achim A.; Dixon, John C.; Zwolinski, Zbigniew

2015-04-01

The currently prepared SEDIBUD Book on "Source-to-Sink Fluxes in Undisturbed Cold Environments" (edited by Achim A. Beylich, John C. Dixon and Zbigniew Zwolinski and published by Cambridge University Press) is summarizing and synthesizing the achievements of the International Association of Geomorphologists` (I.A.G./A.I.G.) Working Group SEDIBUD (Sediment Budgets in Cold Environments), which has been active since 2005 (http://www.geomorph.org/wg/wgsb.html). Amplified climate change and ecological sensitivity of largely undisturbed polar and high-altitude cold climate environments have been highlighted as key global environmental issues. The effects of projected climate change will change surface environments in cold regions and will alter the fluxes of sediments, nutrients and solutes, but the absence of quantitative data and coordinated geomorphic process monitoring and analysis to understand the sensitivity of the Earth surface environment in these largely undisturbed environments is acute. Our book addresses this existing key knowledge gap. The applied approach of integrating comparable and longer-term field datasets on contemporary solute and sedimentary fluxes from a number of different defined cold climate catchment geosystems for better understanding (i) the environmental drivers and rates of contemporary denudational surface processes and (ii) possible effects of projected climate change in cold regions is unique in the field of geomorphology. Largely undisturbed cold climate environments can provide baseline data for modeling the effects of environmental change. The book synthesizes work carried out by numerous SEDIBUD Members over the last decade in numerous cold climate catchment geosystems worldwide. For reaching a global cover of different cold climate environments the book is - after providing an introduction part and a basic part on climate change in cold environments and general implications for solute and sedimentary fluxes - dealing in different defined parts with Sub-Arctic and Arctic Environments, Sub-Antarctic and Antarctic Environments, and Alpine / Mountain Environments. The book includes a synthesis key chapter where comparable datasets on contemporary solute and sedimentary fluxes generated during the conducted coordinated research efforts in different cold climate catchment geosystems are integrated with the key goals to (i) identify the main environmental drivers and rates of contemporary solute and sedimentary fluxes, and (ii) model possible effects of projected climate change on solute and sedimentary fluxes in cold climate environments. The SEDIBUD Book provides new key findings on environmental drivers and rates of contemporary solute and sedimentary fluxes, and on spatial variability within global cold climate environments. The book will go in production in July 2015.

Magnetostratigraphy of displaced Upper Cretaceous strata in southern California

NASA Astrophysics Data System (ADS)

Fry, J. Gilbert; Bottjer, David J.; Lund, Steve P.

1985-09-01

A magnetostratigraphic study of Upper Cretaceous marine strata from the Santa Ana Mountains in southern California has identified a Campanian reversed magnetozone. This reversed interval, corresponding to marine magnetic anomaly 33 34 (Chron 33r) of Campanian age, can be correlated with a Campanian reversed magnetozone that has been reported from strata of the Great Valley Sequence in central California. The Late Cretaceous paleolatitude of the Santa Ana Mountains is estimated from this study to be 26.6°N. This is significantly different from the region's expected Cretaceous paleolatitude of 43.8°N as part of the North American stable craton, and indicates that this region (part of the Peninsular Ranges terrane) was 1900 km farther south in Cretaceous time relative to the stable craton. *Present address: Mobil Oil Corp., P.O. Box 900, Dallas, Texas 75221

Early Bashkirian Rugosa (Anthozoa) from the Donets Basin (Ukraine). Part 6. The Family Aulophyllidae Dybowski, 1873

NASA Astrophysics Data System (ADS)

Fedorowski, Jerzy

2017-12-01

Seven genera (one new), belonging to four subfamilies, seven named species (six new), four species left in open nomenclature and two specimens included in this paper as unnamed Aulophyllidae are described from strata ranging from the lowermost Bashkirian Limestone D510 to the lower Bashkirian Limestone F1. A new genus: Voragoaxum and six new species: Dibunophyllum medium, Dibunophylloides columnatus, D. paulus, D. similis, Voragoaxum cavum and Rozkowskia lenta are introduced. Comparison of the ontogeny of the earliest Bashkirian species of Nina Fedorowski, 2017a and Dibunophylloides Fomichev, 1953 suggest the derivation by descent of the Family Bothrophyllidae from the Subfamily Dibunophyllinae. This means that true bothrophylla are absent in the Mississippian strata of the Western European Province and, perhaps, in the contemporaneous strata of other areas as well.

Variation in the Relationship Between Education and Marriage: Marriage Market Mismatch?

PubMed Central

Musick, Kelly; Brand, Jennie E.; Davis, Dwight

2011-01-01

Educational expansion has led to greater diversity in the social backgrounds of college students. We ask how schooling interacts with this diversity to influence marriage formation among men and women. Relying on data from the 1979 National Longitudinal Survey of Youth (N = 3208), we use a propensity score approach to group men and women into social strata and multilevel event history models to test differences in the effects of college attendance across strata. We find a statistically significant, positive trend in the effects of college attendance across strata, with the largest effects of college on first marriage among the more advantaged and the smallest—indeed, negative—effects among the least advantaged men and women. These findings appear consistent with a mismatch in the marriage market between individuals’ education and their social backgrounds. PMID:22563132

Silicon and Civilization,

DTIC Science & Technology

1980-11-04

less form, or so-called amorphous, as strata of diatomaceous earth , or also in the form of the precious stone--opal. As mentioned, silicon dioxide...skeletons and those of water creatures, which after mortification fall to the bottom of the waters creating strata of diatomaceous earth are also built of...reactions. Likewise, diatomaceous earth has a well developed surface and great adsorptive capa- bility, among others it can absorb a triple excess of

On the palynomorph-based biozones in paleogene strata of rocky mountain basins

USGS Publications Warehouse

Nichols, D.J.

2009-01-01

In a paper published in this journal, and in five previous papers published elsewhere, Lillegraven and McKenna (2008) criticize the research of Nichols and Ott (1978) and Nichols and Flores (2006). They attempt to cast doubt on the validity of the palynomorph-based biozones (the "P- zone" system) applied in strata of Paleocene age throughout the Rocky Mountain region. Their conclusions are without merit.

Spectral stratigraphy

NASA Technical Reports Server (NTRS)

Lang, Harold R.

1991-01-01

A new approach to stratigraphic analysis is described which uses photogeologic and spectral interpretation of multispectral remote sensing data combined with topographic information to determine the attitude, thickness, and lithology of strata exposed at the surface. The new stratigraphic procedure is illustrated by examples in the literature. The published results demonstrate the potential of spectral stratigraphy for mapping strata, determining dip and strike, measuring and correlating stratigraphic sequences, defining lithofacies, mapping biofacies, and interpreting geological structures.

Influence of overpressure on formation velocity evaluation of Neogene strata from the eastern Bengal Basin, Bangladesh

NASA Astrophysics Data System (ADS)

Zahid, Khandaker M.; Uddin, Ashraf

2005-06-01

Interpretation of sonic log data of anticlinal structures from eastern Bangladesh reveals significant variations of acoustic velocity of subsurface strata. The amount of variation in velocity is 32% from Miocene to Pliocene stratigraphic units in Titas and Bakhrabad structure, whereas 21% in Rashidpur structure. Velocity fluctuations are influenced by the presence of gas-bearing horizons, with velocities of gas-producing strata 3-7% lower than laterally equivalent strata at similar depth. Average velocities of Miocene Boka Bil and Bhuban formations are, respectively, 2630 and 3480 m/s at Titas structure; 2820 and 3750 m/s at Bakhrabad; and 3430 and 3843 m/s at the Rashidpur structure. From the overall velocity-depth distribution for a common depth range of 915-3000 m, the Titas, Bakhrabad and Rashidpur structures show a gradual increase in velocity with depth. In contrast, the Sitakund anticline in SE Bangladesh reveals a decrease in velocity with depth from 3000 to 4000 m, probably due to the presence of overpressured mudrocks of the Bhuban Formation. Tectonic compression, associated with the Indo-Burmese plate convergence likely contributed the most toward formation of subsurface overpressure in the Sitakund structure situated in the Chittagong-Tripura Fold Belt of the eastern Bengal basin, Bangladesh.

U-Pb and Hf isotope analysis of detrital zircons from Mesozoic strata of the Gravina belt, southeast Alaska

NASA Astrophysics Data System (ADS)

Yokelson, Intan; Gehrels, George E.; Pecha, Mark; Giesler, Dominique; White, Chelsi; McClelland, William C.

2015-10-01

The Gravina belt consists of Upper Jurassic through Lower Cretaceous marine clastic strata and mafic-intermediate volcanic rocks that occur along the western flank of the Coast Mountains in southeast Alaska and coastal British Columbia. This report presents U-Pb ages and Hf isotope determinations of detrital zircons that have been recovered from samples collected from various stratigraphic levels and from along the length of the belt. The results support previous interpretations that strata in the western portion of the Gravina belt accumulated along the inboard margin of the Alexander-Wrangellia terrane and in a back-arc position with respect to the western Coast Mountains batholith. Our results are also consistent with previous suggestions that eastern strata accumulated along the western margin of the inboard Stikine, Yukon-Tanana, and Taku terranes and in a fore-arc position with respect to the eastern Coast Mountains batholith. The history of juxtaposition of western and eastern assemblages is obscured by subsequent plutonism, deformation, and metamorphism within the Coast Mountains orogen, but may have occurred along an Early Cretaceous sinistral transform system. Our results are inconsistent with models in which an east-facing subduction zone existed along the inboard margin of the Alexander-Wrangellia terrane during Late Jurassic-Early Cretaceous time.

Hierarchical spatial capture-recapture models: Modeling population density from stratified populations

USGS Publications Warehouse

Royle, J. Andrew; Converse, Sarah J.

2014-01-01

Capture–recapture studies are often conducted on populations that are stratified by space, time or other factors. In this paper, we develop a Bayesian spatial capture–recapture (SCR) modelling framework for stratified populations – when sampling occurs within multiple distinct spatial and temporal strata.We describe a hierarchical model that integrates distinct models for both the spatial encounter history data from capture–recapture sampling, and also for modelling variation in density among strata. We use an implementation of data augmentation to parameterize the model in terms of a latent categorical stratum or group membership variable, which provides a convenient implementation in popular BUGS software packages.We provide an example application to an experimental study involving small-mammal sampling on multiple trapping grids over multiple years, where the main interest is in modelling a treatment effect on population density among the trapping grids.Many capture–recapture studies involve some aspect of spatial or temporal replication that requires some attention to modelling variation among groups or strata. We propose a hierarchical model that allows explicit modelling of group or strata effects. Because the model is formulated for individual encounter histories and is easily implemented in the BUGS language and other free software, it also provides a general framework for modelling individual effects, such as are present in SCR models.

Solar Terrestrial Influences on the D Region as Shown by the Level of Atmospheric Radio Noise

NASA Technical Reports Server (NTRS)

Satori, G.; Schaning, B.

1984-01-01

Measurements of the integrated atmospheric radio noise field strength at 27 kHz, used here, were made from 1965 to 1975 at Uppsala, Kuhlungsborn, and Prague-Panska Ves. The large scale meteorological situation was considered by comparing solar disturbed and undisturbed periods under similar weather situations. In order to show the effects of the precipitating high energy particle (HEP) flux and of the Forbush decrease on the noise level between pairs of stations were computed as deviations from the monthly median. Delta E (dB), day by day for all six periods was studied. The correlation coefficients for noon as well as for night values were computed. The correlation coefficients were compared with those for solar undisturbed periods.

The impact of urbanization on family structure: the experience of Sarawak, Malaysia.

PubMed

Sim, Hew Cheng

2003-01-01

This paper argues that women and men encounter the processes of migration and urbanization in very gendered ways. It examines state development policies and their role in accelerating the pace of urbanization, Using material from a recently concluded study on single mothers in the lower socio-economic strata, this paper explores the impact of these wider processes on the structure of the family and women from this strata specifically.

Assessment of undiscovered oil and gas resources in the Eagle Ford Group and associated Cenomanian–Turonian Strata, U.S. Gulf Coast, Texas, 2018

USGS Publications Warehouse

Whidden, Katherine J.; Pitman, Janet K.; Pearson, Ofori N.; Paxton, Stanley T.; Kinney, Scott A.; Gianoutsos, Nicholas J.; Schenk, Christopher J.; Leathers-Miller, Heidi M.; Birdwell, Justin E.; Brownfield, Michael E.; Burke, Lauri A.; Dubiel, Russell F.; French, Katherine L.; Gaswirth, Stephanie B.; Haines, Seth S.; Le, Phuong A.; Marra, Kristen R.; Mercier, Tracey J.; Tennyson, Marilyn E.; Woodall, Cheryl A.

2018-06-22

Using a geology-based assessment methodology, the U.S. Geological Survey estimated undiscovered, technically recoverable mean resources of 8.5 billion barrels of oil and 66 trillion cubic feet of gas in continuous accumulations in the Upper Cretaceous Eagle Ford Group and associated Cenomanian–Turonian strata in onshore lands of the U.S. Gulf Coast region, Texas.

Evidence for gas accumulation associated with diapirism and gas hydrates at the head of the Cape Fear Slide

USGS Publications Warehouse

Schmuck, E.A.; Paull, C.K.

1993-01-01

Single-channel seismic reflection profiles show evidence for areas of significant gas accumulation at the head of the Cape Fear Slide on the continental rise oft North Carolina. Gas accumulation appears to occur beneath a gas hydrate seal in landward-dipping strata and in domed strata associated with diapirism. In addition, gas venting may have occurred near diapirs located at the head of the slide.

Borehole geological assessment

NASA Technical Reports Server (NTRS)

Spuck, W. H., III (Inventor)

1979-01-01

A method and apparatus are discussed for performing geological assessments of a formation located along a borehole, and a boring tool that bores a pair of holes into the walls of the borehole and into the surrounding strata along with a pair of probes which are installed in the holes. One of the probes applies an input such as a current or pressured fluid, and the other probe senses a corresponding input which it receives from the strata.

Integrated biostratigraphic and sequence stratigraphic framework for Upper Cretaceous strata of the eastern Gulf Coastal Plain, USA

USGS Publications Warehouse

Mancini, E.A.; Puckett, T.M.; Tew, B.H.

1996-01-01

Upper Cretaceous (Santonian-Maastrichtian stages) strata of the eastern US Gulf Coastal Plain represent a relatively complete section of marine to nonmarine mixed siliciclastic and carbonate sediments. This section includes three depositional sequences which display characteristic systems tracts and distinct physical defining surfaces. The marine lithofacies are rich in calcareous nannoplankton and planktonic foraminifera which can be used for biostratigraphic zonation. Integration of this zonation with the lithostratigraphy and sequence stratigraphy of these strata results in a framework that can be used for local and regional intrabasin correlation and potentially for global interbasin correlation. Only the synchronous maximum flooding surfaces of these depositional sequences, however, have chronostratigraphic significance. The sequence boundaries and initial flooding surfaces are diachronous, and their use for correlation can produce conflicting results. The availability of high resolution biostratigraphy is critical for global correlation of depositional sequences. ?? 1996 Academic Press Limited.

Law of Strata Pressure Behavior in Shallow Coal Seam

NASA Astrophysics Data System (ADS)

Zhao, Jian; Liu, Leibin; Zheng, Zhiyang

2018-02-01

The law of strata pressure behavior in shallow coal seam is analyzed, according to the load data of Jinjie Coal Mine 31109 working face hydraulic supports. The first weighting distance of main roof is 80 m, and the periodic weighting distance of main roof is about 20 m. And according to the load data in the middle and both ends of the working face, the working resistance of hydraulic supports and the setting load are a bit small, so they couldn’t meet the needs of supporting roof. Then, the front abutment pressure of working face is analyzed by numerical simulation. It does not only explain the reason that the load is too big, but also explains the reason that the strata pressure behavior in shallow coal seam is serious. The length of undamaged main roof rock beam verifies the correctness of the periodic weighting distance.

Vertical heterogeneity in predation pressure in a temperate forest canopy

PubMed Central

Aikens, Kathleen R.; Buddle, Christopher M.

2013-01-01

The forest canopy offers a vertical gradient across which variation in predation pressure implies variation in refuge quality for arthropods. Direct and indirect experimental approaches were combined to assess whether canopy strata differ in ability to offer refuge to various arthropod groups. Vertical heterogeneity in impact of avian predators was quantified using exclosure cages in the understory, lower, mid, and upper canopy of a north-temperate deciduous forest near Montreal, Quebec. Bait trials were completed in the same strata to investigate the effects of invertebrate predators. Exclusion of birds yielded higher arthropod densities across all strata, although treatment effects were small for some taxa. Observed gradients in predation pressure were similar for both birds and invertebrate predators; the highest predation pressure was observed in the understory and decreased with height. Our findings support a view of the forest canopy that is heterogeneous with respect to arthropod refuge from natural enemies. PMID:24010017

The association of urbanisation with the prevalence of dental caries among schoolchildren in Nigeria new capital territory.

PubMed

el-Nadeef, M A; Adegbembo, A O; Honkala, E

1998-02-01

The aim of this study was to examine the association of urbanisation and social class with dental caries. A multi-stage stratified cluster sampling technique was used to select schoolchildren (n = 915). Clinical examination was carried out in daylight according to WHO criteria. The distribution of the subjects between strata was: 315 (urban); 303 (semi-urban) and 297 (rural). The mean age of subjects in each strata was 11.4 years. The mean number of decayed teeth (DT) in the respective strata were 27 per cent; 24 per cent; and 12 per cent. Urban children and semi-urban had higher risk for caries than their rural reference group. Urbanisation had no significant effect on the caries prevalence when social class was controlled except among subjects from the low social class in semi-urban areas. The development of satellite towns around big cities do have implications for planning oral health services.

Two-dimensional resistivity investigation of the North Cavalcade Street site, Houston, Texas, August 2003

USGS Publications Warehouse

Kress, Wade H.; Teeple, Andrew

2005-01-01

Forward modeling was used as an interpretative tool to relate the subsurface distribution of resistivity from four DC resistivity lines to known, assumed, and hypothetical information on subsurface lithologies. The final forward models were used as an estimate of the true resistivity structure for the field data. The forward models and the inversion results of the forward models show the depth, thickness, and extent of strata as well as the resistive anomalies occurring along the four lines and the displacement of strata resulting from the Pecore Fault along two of the four DC resistivity lines. Ten additional DC resistivity lines show similarly distributed shallow subsurface lithologies of silty sand and clay strata. Eight priority areas of resistive anomalies were identified for evaluation in future studies. The interpreted DC resistivity data allowed subsurface stratigraphy to be extrapolated between existing boreholes resulting in an improved understanding of lithologies that can influence contaminant migration.

Spatial characterization of acid rain stress in Canadian Shield Lakes

NASA Technical Reports Server (NTRS)

Tanis, Fred J.

1987-01-01

An analysis was performed to interpret the spatial aspects of lake acidification. Three types of relationships were investigated based upon the August to May seasonal scene pairing. In the first type of analysis ANOVA was used to examine the mean Thematic Mapper band one count by ecophysical strata. The primary difference in the two ecophysical strata is the soil type and depth over the underlying bedrock. Examination of the August to May difference values for TM band one produced similar results. Group A and B strata were the same as above. The third type of analysis examined the relationship between values of the August to May difference from polygons which have similar ecophysical properties with the exception of sulfate deposition. For this case lakes were selected from units with sandy soils over granitic rock types and the sulfate deposition was 1.5 or 2.5 g/sq m/yr.

Neogene Sediment Transport, Deposition, and Exhumation from the Southern Alaska Syntaxis to the Eastern Aleutian Subduction Zone

NASA Astrophysics Data System (ADS)

Ridgway, K. D.; Witmer, J. W.; Enkelmann, E.; Plafker, G.; Brennan, P. R.

2011-12-01

Over 5 km of Neogene sedimentary strata are well exposed in the Chugach-St. Elias Ranges within the southern Alaska syntaxis. This syntaxis forms where the Pacific-North America plate boundary changes from the northwest-trending Queen Charlotte-Fairweather transform system to the southwest-trending Alaska-Aleutian subduction zone. Active collision and subduction of the buoyant Yakutat microplate in the syntaxis results in a wide collisional zone defined by active mountain belts, extensive glaciation, and thick packages of synorogenic strata. New stratigraphic and U-Th/He thermochronologic data from Neogene synorogenic strata, named the Yakataga and Redwood Formations, provide insights on collisional tectonics, glacial erosion, and sediment transport, deposition, burial, and exhumation from the onshore Chugach and St. Elias Ranges to the exposed accretionary prism of the Aleutian trench. Stratigraphic analyses show that along the southeastern part of the syntaxis, Neogene strata are characterized by deposition in braid delta, shallow marine, and glaciomarine slope apron depositional systems that resulted in construction of a broad continental shelf. In the central part of the syntaxis, marine shelf and upper slope environments deposited thick-bedded sandstone and mudstone in a thrust belt/foreland basin system. Along the southwestern part of the syntaxis, Neogene strata were deposited in a regional submarine fan system that filled the easternmost part of the Aleutian trench. Geologic mapping of the contact between the Yakataga Formation and underlying strata along the syntaxis document an angular unconformity with maximum stratigraphic separation (> 5 km) in the central part of the syntaxis. Along strike, this unconformity becomes conformable along both the southwestern and southeastern parts of the syntaxis. The regional angular unconformity and facies transitions both point to the importance of the central part of the syntaxis in the generation and distribution of synorogenic sediment. Apatite and zircon U-Th/He thermochronologic data from granitoid and gneissic clasts in conglomerate suggest that Neogene sediments were buried no deeper than ~2 km in the central and southeastern parts of the syntaxis, and that burial temperatures did not exceed ~40-45°C. In contrast, Neogene sediment deposited by submarine fans in the Aleutian trench along the southwestern part of the syntaxis were buried at depths of 5 to 7.5 km and reached temperatures between ~120-160°C. These strata were subsequently exhumed as the trench fill was incorporated into the growing accretionary prism. Collectively, our data show that the first-order sediment pathway along a glaciated syntaxis is dynamically linked to tectonic uplift, focused glacial erosion, deposition of thick packages of glacial marine sediment, and rapid exhumation along thrust belts and accretionary prisms.

Paleomagnetic data from the Caborca terrane, Mexico: Implications for Cordilleran tectonics and the Mojave-Sonora megashear hypothesis

NASA Astrophysics Data System (ADS)

Molina Garza, Roberto S.; Geissman, John W.

1999-04-01

Two ancient magnetizations have been isolated in rocks of the Caborca terrane, northwest Mexico. The characteristic magnetizations of Neoproterozoic and Paleozoic miogeoclinal shelf-strata, arc-derived Lower Jurassic marine strata, and Jurassic volcanic and volcaniclastic rocks are of dual polarity and east-northeast declination (or south-southwest) and shallow inclination. Magnetizations in Neoproterozoic and Paleozoic miogeoclinal strata are interpreted as secondary (J*) and to be of similar age to those observed in Lower and Middle Jurassic rocks. Remanence acquisition is bracketed between about 190 and 160 Ma. The overall mean (D=15.0°, I=8.5° n=38 sites; six localities; k=19.1, α95=5.5°) suggests a moderate to large clockwise rotation of 12 to 50° (depending on reference direction assumed) of the Caborca terrane, and rocks of the Sonoran segment of the Cordilleran volcanic arc, with respect to the North America craton. When compared with expected inclinations, observed values are not anomalously steep, arguing against statistically significant southward latitudinal displacement of the Caborca block after remanence acquisition. Late Cretaceous intrusions yield primary, dual-polarity steep inclination ``K'' magnetizations (D=341.4°, I=52.3° n=10 sites; five localities; k=38.3, α95=7.9°) and have locally remagnetized Neoproterozoic and Jurassic strata. When present, secondary (K*) magnetizations in Neoproterozoic strata are of higher coercivity and higher unblocking temperature than the characteristic (J*) magnetization. Importantly, the regional internal consistency of data for Late Cretaceous intrusions suggests that effects of Tertiary tilt or rotation about a vertical axis over the broad region sampled (~5000 km2) are not substantial. Late Cretaceous primary (K) magnetizations and secondary (K*) magnetizations yield a combined mean of D=348.1°, I=50.7° (N=10 localities; 47 sites; k=53.5, α95=6.7°), indicating at most small (<~10°) clockwise rotation of the Caborca region with respect to the craton. Permissible post-Late Cretaceous latitudinal displacement is near or below the detection limit of paleomagnetism (<~300 km). Limited data from Lower Cretaceous strata of the Bisbee Group (D=339.9°, I=47.9° n=4 sites) suggest that the modest clockwise rotations inferred on the basis of J* magnetizations in Jurassic and older strata occurred in Jurassic time. Together, the lack of evidence for southward displacement, yet evidence for statistically significant clockwise rotation, and the overall similarity of Jurassic magnetizations in the Cordilleran arc with those of the Caborca block, despite the fact that some of them are clearly secondary, are not consistent with the Mojave-Sonora megashear hypothesis of Late Jurassic left-lateral strike-slip motion of the crust of northern Mexico.

Forests and Their Canopies: Achievements and Horizons in Canopy Science.

PubMed

Nakamura, Akihiro; Kitching, Roger L; Cao, Min; Creedy, Thomas J; Fayle, Tom M; Freiberg, Martin; Hewitt, C N; Itioka, Takao; Koh, Lian Pin; Ma, Keping; Malhi, Yadvinder; Mitchell, Andrew; Novotny, Vojtech; Ozanne, Claire M P; Song, Liang; Wang, Han; Ashton, Louise A

2017-06-01

Forest canopies are dynamic interfaces between organisms and atmosphere, providing buffered microclimates and complex microhabitats. Canopies form vertically stratified ecosystems interconnected with other strata. Some forest biodiversity patterns and food webs have been documented and measurements of ecophysiology and biogeochemical cycling have allowed analyses of large-scale transfer of CO 2 , water, and trace gases between forests and the atmosphere. However, many knowledge gaps remain. With global research networks and databases, and new technologies and infrastructure, we envisage rapid advances in our understanding of the mechanisms that drive the spatial and temporal dynamics of forests and their canopies. Such understanding is vital for the successful management and conservation of global forests and the ecosystem services they provide to the world. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Lithofacies control in detrital zircon provenance studies: Insights from the Cretaceous Methow basin, southern Canadian Cordillera

USGS Publications Warehouse

DeGraaff-Surpless, K.; Mahoney, J.B.; Wooden, J.L.; McWilliams, M.O.

2003-01-01

High-frequency sampling for detrital zircon analysis can provide a detailed record of fine-scale basin evolution by revealing the temporal and spatial variability of detrital zircon ages within clastic sedimentary successions. This investigation employed detailed sampling of two sedimentary successions in the Methow/Methow-Tyaughton basin of the southern Canadian Cordillera to characterize the heterogeneity of detrital zircon signatures within single lithofacies and assess the applicability of detrital zircon analysis in distinguishing fine-scale provenance changes not apparent in lithologic analysis of the strata. The Methow/Methow-Tyaughton basin contains two distinct stratigraphic sequences of middle Albian to Santonian clastic sedimentary rocks: submarine-fan deposits of the Harts Pass Formation/Jackass Mountain Group and fluvial deposits of the Winthrop Formation. Although both stratigraphic sequences displayed consistent ranges in detrital zircon ages on a broad scale, detailed sampling within each succession revealed heterogeneity in the detrital zircon age distributions that was systematic and predictable in the turbidite succession but unpredictable in the fluvial succession. These results suggest that a high-density sampling approach permits interpretation of finescale changes within a lithologically uniform turbiditic sedimentary succession, but heterogeneity within fluvial systems may be too large and unpredictable to permit accurate fine-scale characterization of the evolution of source regions. The robust composite detrital zircon age signature developed for these two successions permits comparison of the Methow/Methow-Tyaughton basin age signature with known plutonic source-rock ages from major plutonic belts throughout the Cretaceous North American margin. The Methow/Methow-Tyaughton basin detrital zircon age signature matches best with source regions in the southern Canadian Cordillera, requiring that the basin developed in close proximity to the southern Canadian Cordillera and providing evidence against large-scale dextral translation of the Methow terrane.

Features of abandoned cemetery soils on sandy substrates in Northern Poland

NASA Astrophysics Data System (ADS)

Majgier, L.; Rahmonov, O.; Bednarek, R.

2014-06-01

Morphological and chemical features of cemetery soils (Necrosols and undisturbed cemetery soils) have been studied with Northern Poland as an example. Special attention has been given to the contents of the total phosphorus (as an indicator of the anthropogenic impact); the organic carbon; the total nitrogen; the calcium carbonate; and the changes in the acidity and total Ca, Na, K, Al, Fe, Mg, Zn, Cd, and Pb. The soil profiles have been compared to the control soil (a Brunic Arenosol according to the WRB classification) occurring beyond the cemetery area. The changes in the studied burial soils are mainly manifested in their morphology: the disturbance of the primary genetic horizons and the presence of mixed soil horizons and artifacts (bones, coffin remains, limestone-concrete debris of the cemetery infrastructure). Such changes in the chemical properties as an increase in the contents of the organic carbon and total nitrogen and the soil reaction were observed. Our studies have shown that the highest Ptotal concentration is observed in the A horizons of the anthropogenic burial horizons and undisturbed cemetery soils. The content of phosphorus in the Necrosols is significantly higher than that in the control soil profile, as is observed for the Cgrb layers of burial Necrosols. The morphology and chemistry of the undisturbed cemetery soils are very similar to those of the control profile.

The food matrix and sterol characteristics affect the plasma cholesterol lowering of phytosterol/phytostanol.

PubMed

Cusack, Laura Kells; Fernandez, Maria Luz; Volek, Jeff S

2013-11-01

Foods with added phytosterols/phytostanols (PS) are recommended to lower LDL cholesterol (LDL-c) concentrations. Manufacturers have incorporated PS into a variety of common foods. Understanding the cholesterol-lowering impact of the food matrix and the PS characteristics would maximize their success and increase the benefit to consumers. This review systematically examines whether the PS characteristics and the fatty acid composition of foods with added PS affects serum LDL-c. A total of 33 studies published between the years 1998 and 2011 inclusive of 66 individual primary variables (strata) were evaluated. The functional food matrices included margarine, mayonnaise, yogurt, milk, cheese, meat, grain, juice, and chocolate. Consistently, ≥10% reductions in LDL-c were reported when the characteristics of the food matrix included poly- and monounsaturated fatty acids known to lower LDL-c. Also, >10% mean reductions in LDL-c were reported when β-sitostanol and campestanol as well as stanol esters were used. These characteristics allow both low-fat and high-fat foods to successfully incorporate PS and significantly lower LDL-c.

Some remarks relating to Short Notice Random Inspection (SNRI) and verification of flow strata

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

Murphey, W.; Emeigh, C.; Lessler, L.

1991-01-01

Short Notice Random Inspection (SNRI) is a concept which is to enable the International Atomic Energy Agency (Agency) to make technically valid statements of verification of shipment or receipt strata when the Agency cannot have a resident inspector. Gordon and Sanborn addressed this problem for a centrifuge enrichment plant. In this paper other operating conditions of interest are examined and modifications of the necessary conditions for application of SNRI discussed.

Planning Beyond Tactics: Towards a Military Application of the Philosophy of Design in the Formulation of Strategy

DTIC Science & Technology

2008-05-22

mimicry etc.). But this is only true on the level of the strata – a parallelism between two strata such that a plant organization on one imitates...existing planning structure, but augments it, increasing the relevance of subordinate actions to both the desires of commanders and the environment they...acute observation, and a familiarity and ease with ambiguity. In every sense design is philosophy embracing ever- increasing complexity. Thinking

Evidence for gas accumulation associated with diapirism and gas hydrates at the head of the Cape Fear Slide

USGS Publications Warehouse

Schmuck, E.A.; Paull, C.K.

1993-01-01

Single-channel seismic reflection profiles show evidence for areas of significant gas accumulation at the head of the Cape Fear Slide on the continental rise off North Carolina. Gas accumulation appears to occur beneath a gas hydrate seal in landward-dipping strata and in domed strata associated with diapirism. In addition, gas venting may have occurred near diapirs located at the head of the slide. ?? 1993 Springer-Verlag.

Power of tests for comparing trend curves with application to national immunization survey (NIS).

PubMed

Zhao, Zhen

2011-02-28

To develop statistical tests for comparing trend curves of study outcomes between two socio-demographic strata across consecutive time points, and compare statistical power of the proposed tests under different trend curves data, three statistical tests were proposed. For large sample size with independent normal assumption among strata and across consecutive time points, the Z and Chi-square test statistics were developed, which are functions of outcome estimates and the standard errors at each of the study time points for the two strata. For small sample size with independent normal assumption, the F-test statistic was generated, which is a function of sample size of the two strata and estimated parameters across study period. If two trend curves are approximately parallel, the power of Z-test is consistently higher than that of both Chi-square and F-test. If two trend curves cross at low interaction, the power of Z-test is higher than or equal to the power of both Chi-square and F-test; however, at high interaction, the powers of Chi-square and F-test are higher than that of Z-test. The measurement of interaction of two trend curves was defined. These tests were applied to the comparison of trend curves of vaccination coverage estimates of standard vaccine series with National Immunization Survey (NIS) 2000-2007 data. Copyright © 2011 John Wiley & Sons, Ltd.

Clustering network layers with the strata multilayer stochastic block model.

PubMed

Stanley, Natalie; Shai, Saray; Taylor, Dane; Mucha, Peter J

2016-01-01

Multilayer networks are a useful data structure for simultaneously capturing multiple types of relationships between a set of nodes. In such networks, each relational definition gives rise to a layer. While each layer provides its own set of information, community structure across layers can be collectively utilized to discover and quantify underlying relational patterns between nodes. To concisely extract information from a multilayer network, we propose to identify and combine sets of layers with meaningful similarities in community structure. In this paper, we describe the "strata multilayer stochastic block model" (sMLSBM), a probabilistic model for multilayer community structure. The central extension of the model is that there exist groups of layers, called "strata", which are defined such that all layers in a given stratum have community structure described by a common stochastic block model (SBM). That is, layers in a stratum exhibit similar node-to-community assignments and SBM probability parameters. Fitting the sMLSBM to a multilayer network provides a joint clustering that yields node-to-community and layer-to-stratum assignments, which cooperatively aid one another during inference. We describe an algorithm for separating layers into their appropriate strata and an inference technique for estimating the SBM parameters for each stratum. We demonstrate our method using synthetic networks and a multilayer network inferred from data collected in the Human Microbiome Project.

Numerical Modeling of Mechanical Behavior for Buried Steel Pipelines Crossing Subsidence Strata

PubMed Central

Han, C. J.

2015-01-01

This paper addresses the mechanical behavior of buried steel pipeline crossing subsidence strata. The investigation is based on numerical simulation of the nonlinear response of the pipeline-soil system through finite element method, considering large strain and displacement, inelastic material behavior of buried pipeline and the surrounding soil, as well as contact and friction on the pipeline-soil interface. Effects of key parameters on the mechanical behavior of buried pipeline were investigated, such as strata subsidence, diameter-thickness ratio, buried depth, internal pressure, friction coefficient and soil properties. The results show that the maximum strain appears on the outer transition subsidence section of the pipeline, and its cross section is concave shaped. With the increasing of strata subsidence and diameter-thickness ratio, the out of roundness, longitudinal strain and equivalent plastic strain increase gradually. With the buried depth increasing, the deflection, out of roundness and strain of the pipeline decrease. Internal pressure and friction coefficient have little effect on the deflection of buried pipeline. Out of roundness is reduced and the strain is increased gradually with the increasing of internal pressure. The physical properties of soil have a great influence on the mechanical properties of buried pipeline. The results from the present study can be used for the development of optimization design and preventive maintenance for buried steel pipelines. PMID:26103460

Beetle assemblages from an Australian tropical rainforest show that the canopy and the ground strata contribute equally to biodiversity

PubMed Central

Stork, Nigel E; Grimbacher, Peter S

2006-01-01

There remains great uncertainty about how much tropical forest canopies contribute to global species richness estimates and the relative specialization of insect species to vertical zones. To investigate these issues, we conducted a four-year sampling program in lowland tropical rainforest in North Queensland, Australia. Beetles were sampled using a trap that combines Malaise and flight interception trap (FIT) functions. Pairs of this trap, one on the ground and a second suspended 15–20 m above in the canopy were located at five sites, spaced 50 m or more apart. These traps produced 29 986 beetles of 1473 species and 77 families. There were similar numbers of individuals (canopy 14 473; ground 15 513) and species (canopy 1158; ground 895) in each stratum, but significantly more rare species in the canopy (canopy 509; ground 283). Seventy two percent of the species (excluding rare species) were found in both strata. Using IndVal, we found 24 and 27% of the abundant species (n≥20 individuals) to be specialized to the canopy and the ground strata, respectively, and equivalent analyses at the family level showed figures of 30 and 22%, respectively. These results show that the canopy and the ground strata both provide important contributions to rainforest biodiversity. PMID:16822759

Cardiorespiratory parameters and their relation with gestational age and level of oral feeding skills in preterm infants.

PubMed

Yamamoto, Raquel Coube de Carvalho; Prade, Leila Sauer; Berwig, Luana Cristina; Weinmann, Angela Regina Maciel; Keske-Soares, Márcia

2016-01-01

To correlate cardiorespiratory parameters with gestational age and level of oral feeding skills in the first oral feeding in preterm infants. Study participants were 37 clinically stable preterm infants. Cardiorespiratory rate was assessed before and after introduction of oral feeding. The newborns were divided into three strata according to gestational age at birth. Oral skill was classified into four levels: I - low oral skill and low resistance to feeding; II - low oral skill and high resistance to feeding; III - high oral skill and low resistance to feeding; IV - high oral skill and high resistance to feeding. No difference was observed in heart and respiratory rate between the strata of gestational age at birth and between the levels of oral skill. Comparison between pre- and post-cardiorespiratory rates within each level of oral skill and stratum of gestational age showed difference between heart rate in the strata of gestational ages of 30 to 33 weeks and of 34 to 36 weeks, as well as between oral skill of levels I, II, and IV. With regard to the comparison between pre- and post- respiratory rates, difference was found in the oral skill of level I. Differences were observed between pre- and post-prandial cardiorespiratory rates regarding the first oral feeding, as well as between strata of gestational age at birth and levels of oral feeding skills.

Structural architecture of the central Brooks Range foothills, Alaska

USGS Publications Warehouse

Moore, Thomas E.; Potter, Christopher J.; O'Sullivan, Paul B.

2002-01-01

Five structural levels underlie the Brooks Range foothills, from lowest to highest: (1) autochthon, at a depth of ~9 km; (2) Endicott Mountains allochthon (EMA), thickest under the northern Brooks Range (>15 km) and wedging out northward above the autochthon; (3) higher allochthons (HA), with a composite thickness of 1.5+ km, wedging out northward at or beyond the termination of EMA; (4) Aptian-Albian Fortress Mountain Formation (FM), deposited unconformably on deformed EMA and HA and thickening northward into a >7-km-thick succession of deformed turbidites (Torok Formation); (5) gently folded Albian-Cenomanian deltaic deposits (Nanushuk Group). The dominant faulting pattern in levels 2-3 is thin-skinned thrusting and thrust-related folds formed before deposition of Cretaceous strata. These structures are cut by younger steeply south-dipping reverse faults that truncate and juxtapose structural levels 1-4 and expose progressively deeper structural levels to the south. Structural levels 4-5 are juxtaposed along a north-dipping zone of south-vergent folds and thrusts. Stratigraphic and fission-track age data suggest a kinematic model wherein the foothills belt was formed first, by thrusting of HA and EMA as deformational wedges onto the regionally south-dipping authochon at 140-120Ma. After deposition of FM and Torok during mid-Cretaceous hinterland extension and uplift, a second episode of contractional deformation at 60 Ma shortened the older allochthonous deformational wedges (EMA, HA) and overlying strata on north-vergent reverse faults. To the north, where the allochthons wedge out, shortening caused duplexing in the Torok and development of a triangle zone south of the Tuktu escarpment.

Prediction methods of spudcan penetration for jack-up units

NASA Astrophysics Data System (ADS)

Zhang, Ai-xia; Duan, Meng-lan; Li, Hai-ming; Zhao, Jun; Wang, Jian-jun

2012-12-01

Jack-up units are extensively playing a successful role in drilling engineering around the world, and their safety and efficiency take more and more attraction in both research and engineering practice. An accurate prediction of the spudcan penetration depth is quite instrumental in deciding on whether a jack-up unit is feasible to operate at the site. The prediction of a too large penetration depth may lead to the hesitation or even rejection of a site due to potential difficulties in the subsequent extraction process; the same is true of a too small depth prediction due to the problem of possible instability during operation. However, a deviation between predictive results and final field data usually exists, especially when a strong-over-soft soil is included in the strata. The ultimate decision sometimes to a great extent depends on the practical experience, not the predictive results given by the guideline. It is somewhat risky, but no choice. Therefore, a feasible predictive method for the spudcan penetration depth, especially in strata with strong-over-soft soil profile, is urgently needed by the jack-up industry. In view of this, a comprehensive investigation on methods of predicting spudcan penetration is executed. For types of different soil profiles, predictive methods for spudcan penetration depth are proposed, and the corresponding experiment is also conducted to validate these methods. In addition, to further verify the feasibility of the proposed methods, a practical engineering case encountered in the South China Sea is also presented, and the corresponding numerical and experimental results are also presented and discussed.

Life on the edge in eastern Alaska: Basal Ordovician(Tremadocian), platform-margin faunas of the Jones Ridge Formation

USGS Publications Warehouse

Taylor, J. F.; Allen, T. J.; Repetski, John E.; Strauss, J. V.; Irwin, S. J.

2015-01-01

As the most fossiliferous and least deformed succession of unequivocally Laurentian lower Paleozoic strata in Alaska, the Jones Ridge Limestone has provided critical data for numerous stratigraphic studies (e. g. Palmer 1968; Harris et al. 1995; Dumoulin et al. 2002; Dumoulin and Harris 2012) focused on the Cambrian and Ordovician of northwestern North America/northeastern Laurentia (Figure 1). The Jones Ridge faunas are also significant in having provided the type material for some of the widespread and biostratigraphically useful latest Furongian and (perhaps) earliest Tremadocian species described by Kobayashi (1936) and Palmer (1968). Unfortunately, some of those taxa were based on very limited material for which, in the earlier study in particular, no detailed information regarding locality or stratigraphic horizon was provided. The limited amount of information and material available for study from Jones Ridge results largely from its remote location on the Yukon-Alaska boundary approximately 25km north of Eagle, Alaska, which renders it accessible only by helicopter. Parts of three field seasons (2010, 2011, and 2014) were invested in re-description and intensive sampling of the type section of the Jones Ridge Formation in order to produce an integrated and greatly refined set of biostratigraphic, chemostratigraphic, and sedimentological data. The new data support the interpretation offered by Palmer (1968) of the Jones Ridge strata as the product of deposition in outermost platform to upper slope environments offered by Palmer (1968) on the basis of taxonomic content of the faunas and close proximity of deep water units of equivalent age a very short distance to the southwest.

Ichnology and paleosubstrates of Austin Chalk (Cretaceous) outcrops: Southern Dallas and Ellis Counties, Texas

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

Dawson, W.C.; Reaser, D.F.

1991-03-01

Ichnofossils are abundant in outcrops of the Austin Chalk near Waxahachie, Texas (designated site of the Super-Conducting Super Collider). The abundance and diversity of ichnofossils in Austin strata contrast with the paucity of other macrofossils, except large inoceramids. The lower Austin Chalk (Coniacian) disconformably overlies the Eagle Ford Shale (Turonian). Planolites, Thalassinoides, and Chondrites are conspicuous in the lower Austin. Some lower Austin strata contain well-preserved burrows having menicus fillings. However, most lower Austin ichnofossils are poorly preserved and have compacted. The middle Austin Marl and upper Austin Chalk (Santonain) contain Planolites, Chondrites, Thalassinoides, and Pseudobilobites. Several thin, intensely burrowed,more » Fe-stained, horizons within the middle Austin represent omission surfaces having postomission Thalassinoides. The upper Austin disconformably underlies the Taylor Marl (Campanian). The Austin-Taylor contact is a Rhizocorallium-infested omission surface overlain by a condensed bed of phosphatic and pyritic bioclasts. Upper Austin occurrences of Rhizocorallium and Pseudobilobites are unique for North American Cretaceous chalks. Based on cross-cutting relationships and differences in morphology, diameter, and burrow-filling sediments, numerous ichnospecies of Thalassinoides are discernable throughout the Austin. Variations in preservation quality exhibited by successive generations of ichnofossils record progressive changes in substrate consistency. Earliest formed burrows have diffuse outlines representing an initial thixotropic (softground) Austin substrate. Subsequent generations of burrows have more distinct outlines recording a gradual increase in substrate firmness. Paleo-firmgrounds are common in Austin outcrops; evidence of hardgrounds is lacking. The Thalassinoides-dominated Austin ichnoassemblage represents an inner shelf paleoenvironment.« less

Public water fluoridation and dental health in New South Wales.

PubMed

Armfield, Jason M

2005-10-01

To evaluate whether access to fluoridated public water in New South Wales (NSW) is related to both a reduction in caries experience within NSW regions and to better dental health for disadvantaged children. Cross-sectional population data on children attending the School Dental Service in NSW in 2000 were used to calculate and compare the number of decayed, missing and filled teeth (dmft/ DMFT) across areas of differing availability of fluoridated water within NSW Area Health Service (AHS) regions. Analyses were also undertaken looking at differences in caries between optimally fluoridated and non-fluoridated communities across strata of socio-economic disadvantage and by Indigenous status. A total sample of 248,944 children aged 3-15 years was obtained. Caries experience in the deciduous dentition of 5-6 year-olds and the permanent dentition of 11-12 year-olds was significantly lower for children in fluoridated areas than nonfluoridated areas in six of the eight AHSs and six of the 10 AHSs respectively where comparisons could be made. Children living in fluoridated areas had lower caries experience than children living in nonfluoridated areas, regardless of socio-economic disadvantage. Both Indigenous and non-Indigenous children had reduced caries experience in fluoridated compared with non-fluoridated areas. Water fluoridation was found to be related to significantly reduced caries experience in the majority of AHSs where comparisons could be made, and to benefit all socio-economic strata of the community. Water fluoridation should be extended to those areas of NSW that are yet to benefit from this successful caries preventive public health initiative.

A large-scale field assessment of carbon stocks in human-modified tropical forests.

PubMed

Berenguer, Erika; Ferreira, Joice; Gardner, Toby Alan; Aragão, Luiz Eduardo Oliveira Cruz; De Camargo, Plínio Barbosa; Cerri, Carlos Eduardo; Durigan, Mariana; Cosme De Oliveira Junior, Raimundo; Vieira, Ima Célia Guimarães; Barlow, Jos

2014-12-01

Tropical rainforests store enormous amounts of carbon, the protection of which represents a vital component of efforts to mitigate global climate change. Currently, tropical forest conservation, science, policies, and climate mitigation actions focus predominantly on reducing carbon emissions from deforestation alone. However, every year vast areas of the humid tropics are disturbed by selective logging, understory fires, and habitat fragmentation. There is an urgent need to understand the effect of such disturbances on carbon stocks, and how stocks in disturbed forests compare to those found in undisturbed primary forests as well as in regenerating secondary forests. Here, we present the results of the largest field study to date on the impacts of human disturbances on above and belowground carbon stocks in tropical forests. Live vegetation, the largest carbon pool, was extremely sensitive to disturbance: forests that experienced both selective logging and understory fires stored, on average, 40% less aboveground carbon than undisturbed forests and were structurally similar to secondary forests. Edge effects also played an important role in explaining variability in aboveground carbon stocks of disturbed forests. Results indicate a potential rapid recovery of the dead wood and litter carbon pools, while soil stocks (0-30 cm) appeared to be resistant to the effects of logging and fire. Carbon loss and subsequent emissions due to human disturbances remain largely unaccounted for in greenhouse gas inventories, but by comparing our estimates of depleted carbon stocks in disturbed forests with Brazilian government assessments of the total forest area annually disturbed in the Amazon, we show that these emissions could represent up to 40% of the carbon loss from deforestation in the region. We conclude that conservation programs aiming to ensure the long-term permanence of forest carbon stocks, such as REDD+, will remain limited in their success unless they effectively avoid degradation as well as deforestation. © 2014 The Authors. Global Change Biology Published by John Wiley & Sons Ltd.

Local seismic hazard assessment in explosive volcanic settings by 3D numerical analyses

NASA Astrophysics Data System (ADS)

Razzano, Roberto; Pagliaroli, Alessandro; Moscatelli, Massimiliano; Gaudiosi, Iolanda; Avalle, Alessandra; Giallini, Silvia; Marcini, Marco; Polpetta, Federica; Simionato, Maurizio; Sirianni, Pietro; Sottili, Gianluca; Vignaroli, Gianluca; Bellanova, Jessica; Calamita, Giuseppe; Perrone, Angela; Piscitelli, Sabatino

2017-04-01

This work deals with the assessment of local seismic response in the explosive volcanic settings by reconstructing the subsoil model of the Stracciacappa maar (Sabatini Volcanic District, central Italy), whose pyroclastic succession records eruptive phases ended about 0.09 Ma ago. Heterogeneous characteristics of the Stracciacappa maar (stratification, structural setting, lithotypes, and thickness variation of depositional units) make it an ideal case history for understanding mechanisms and processes leading to modifications of amplitude-frequency-duration of seismic waves generated at earthquake sources and propagating through volcanic settings. New geological map and cross sections, constrained with recently acquired geotechnical and geophysical data, illustrate the complex geometric relationships among different depositional units forming the maar. A composite interfingering between internal lacustrine sediments and epiclastic debris, sourced from the rim, fills the crater floor; a 45 meters thick continuous coring borehole was drilled in the maar with sampling of undisturbed samples. Electrical Resistivity Tomography surveys and 2D passive seismic arrays were also carried out for constraining the geological model and the velocity profile of the S-waves, respectively. Single station noise measurements were collected in order to define natural amplification frequencies. Finally, the nonlinear cyclic soil behaviour was investigated through simple shear tests on the undisturbed samples. The collected dataset was used to define the subsoil model for 3D finite difference site response numerical analyses by using FLAC 3D software (ITASCA). Moreover, 1D and 2D numerical analyses were carried out for comparison purposes. Two different scenarios were selected as input motions: a moderate magnitude (volcanic event) and a high magnitude (tectonic event). Both earthquake scenarios revealed significant ground motion amplification (up to 15 in terms of spectral acceleration at about 1 s) essentially related to 2D/3D phenomena associated to sharp lateral variations of mechanical properties within the Stracciacappa maar. Our results are relevant to face the assessment of local seismic response in similar volcanic settings in highly urbanised environments elsewhere.

Spread dynamics of perennial pepperweed (Lepidium latifolium) in two seasonal wetland areas

USGS Publications Warehouse

Renz, Mark J.; Steinmaus, Scott J.; Gilmer, David S.; DiTomaso, Joseph M.

2012-01-01

Perennial pepperweed is an invasive plant that is expanding rapidly in several plant communities in the western United States. In California, perennial pepperweed has aggressively invaded seasonal wetlands, resulting in degradation of habitat quality. We evaluated the rate and dynamics of population spread, assessed the effect of disturbance on spread, and determined the biotic and abiotic factors influencing the likelihood of invasion. The study was conducted at eight sites within two wetland regions of California. Results indicate that in undisturbed sites, spread was almost exclusively through vegetative expansion, and the average rate of spread was 0.85 m yr−1 from the leading edge. Spread in sites that were disked was more than three times greater than in undisturbed sites. While smaller infestations increased at a faster rate compared with larger populations, larger infestations accumulated more newly infested areas than smaller infestations from year to year. Stem density was consistently higher in the center of the infestations, with about 2.4 times more stems per square meter compared with the leading edge at the perimeter of the population. The invasion by perennial pepperweed was positively correlated with increased water availability but was negatively correlated with the cover of perennial and annual species. Thus, high cover of resident vegetation can have a suppressive effect on the rate of invasion, even in wetland ecosystems. On the basis of these results, we recommend that resident plant cover not be disturbed, especially in wet areas adjacent to areas currently infested with perennial pepperweed. For infested areas, management efforts should be prioritized to focus on controlling satellite populations as well as the leading edge of larger infestations first. This strategy could reduce the need for costly active restoration efforts by maximizing the probability of successful re-establishment of resident vegetation from the adjacent seedbank.

Secondary succession of arthropods and plants in the Arizona Sonoran Desert in response to transmission line construction

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

Johnson, C.D.; Beley, J.R.; Ditsworth, T.M.

1983-03-01

At a site about 16 km south of Black Canyon City, Arizona, density of arthropods on an undisturbed plot after an access road was built for powerline construction was much greater than on a disturbed plot. Mites, springtails, leafhoppers, scale insects, ants and thrips were signficantly reduced on the disturbed area. Our results indicate that restoration of numbers of arthropods on the disturbed area is dependent on the total plant cover on the plot, apparently regardless of the composition of the plant species involved. It is obvious in this area that the plant communities will remain dissimilar, with the pioneeringmore » herbaceous plants on the disturbed plot dominating. Cosntruction of a powerline apparently has had little impact on the structure of the arthropod community on the disturbed area, as proportions of three trophic categories of arthropods have not been radically altered. The results of this study, when compared to other studies in the Sonoran Desert and in desert grasslands disturbed by powerline construction, indicate that lengthy secondary succession does occur in the Sonoran Desert. Early arthropod invaders were found to be mainly herbivores, with few parasites or predators, and an equilibrium was eventually reached between colonizers and space requirements.« less

A simplified 137Cs transport model for estimating erosion rates in undisturbed soil.

PubMed

Zhang, Xinbao; Long, Yi; He, Xiubin; Fu, Jiexiong; Zhang, Yunqi

2008-08-01

(137)Cs is an artificial radionuclide with a half-life of 30.12 years which released into the environment as a result of atmospheric testing of thermo-nuclear weapons primarily during the period of 1950s-1970s with the maximum rate of (137)Cs fallout from atmosphere in 1963. (137)Cs fallout is strongly and rapidly adsorbed by fine particles in the surface horizons of the soil, when it falls down on the ground mostly with precipitation. Its subsequent redistribution is associated with movements of the soil or sediment particles. The (137)Cs nuclide tracing technique has been used for assessment of soil losses for both undisturbed and cultivated soils. For undisturbed soils, a simple profile-shape model was developed in 1990 to describe the (137)Cs depth distribution in profile, where the maximum (137)Cs occurs in the surface horizon and it exponentially decreases with depth. The model implied that the total (137)Cs fallout amount deposited on the earth surface in 1963 and the (137)Cs profile shape has not changed with time. The model has been widely used for assessment of soil losses on undisturbed land. However, temporal variations of (137)Cs depth distribution in undisturbed soils after its deposition on the ground due to downward transport processes are not considered in the previous simple profile-shape model. Thus, the soil losses are overestimated by the model. On the base of the erosion assessment model developed by Walling, D.E., He, Q. [1999. Improved models for estimating soil erosion rates from cesium-137 measurements. Journal of Environmental Quality 28, 611-622], we discuss the (137)Cs transport process in the eroded soil profile and make some simplification to the model, develop a method to estimate the soil erosion rate more expediently. To compare the soil erosion rates calculated by the simple profile-shape model and the simple transport model, the soil losses related to different (137)Cs loss proportions of the reference inventory at the Kaixian site of the Three Gorge Region, China are estimated by the two models. The over-estimation of the soil loss by using the previous simple profile-shape model obviously increases with the time period from the sampling year to the year of 1963 and (137)Cs loss proportion of the reference inventory. As to 20-80% of (137)Cs loss proportions of the reference inventory at the Kaixian site in 2004, the annual soil loss depths estimated by the new simplified transport process model are only 57.90-56.24% of the values estimated by the previous model.

Quantifying porosity and permeability of fractured carbonates and fault rocks in natural groundwater reservoirs

NASA Astrophysics Data System (ADS)

Pirmoradi, Reza; Wolfmayr, Mariella; Bauer, Helene; Decker, Kurt

2017-04-01

This study presents porosity and permeability data for a suite of different carbonate rocks from two major groundwater reservoirs in eastern Austria that supply more than 60% of Vienna`s drinking water. Data includes a set of lithologically different, unfractured host rocks, fractured rocks with variable fracture intensities, and fault rocks such as dilation breccias, different cataclasites and dissolution-precipitation fault rocks. Fault rock properties are of particular importance, since fault zones play an important role in the hydrogeology of the reservoirs. The reservoir rocks are exposed at two major alpine karst plateaus in the Northern Calcareous Alps. They comprise of various Triassic calcareous strata of more than 2 km total thickness that reflect facies differentiation since Anisian times. Rocks are multiply deformed resulting in a partly dense network of fractures and faults. Faults differ in scale, fault rock content, and fault rock volumes. Methods used to quantify the porosity and permeability of samples include a standard industry procedure that uses the weight of water saturated samples under hydrostatic uplift and in air to determine the total effective (matrix and fracture) porosity of rocks, measurements on plugs with a fully automated gas porosity- and permeameter using N2 gas infiltrating plugs under a defined confining pressure (Coreval Poro 700 by Vinci technologies), and percolation tests. The latter were conducted in the field along well known fault zones in order to test the differences in fractured rock permeability in situ and on a representative volume, which is not ensured with plug measurements. To calculate hydraulic conductivity by the Darcy equation the measured elapsed time for infiltrating a standard volume of water into a small borehole has been used. In general, undisturbed host rock samples are all of low porosity (average around 1%). The open porosity of the undisturbed rocks belonging to diverse formations vary from 0.18% to 2.35%. Klinkenberg permeabilities of plugs range from 0.001mD to about 0.6mD thus spreading over three orders of magnitude. Fractured rocks show significantly higher porosities (3% average) with respect to the undeformed country rocks. Plug measurements reveal quite low permeabilities (< 1mD) for this type of rock, which is owed to the measuring technique, where fractures are closed under confining pressure. A second important point is that intensely fractured rocks are underrepresented in the data as they cannot be plugged adequately. Percolation tests give better information for fractured rock permeabilities and revealed hydraulic conductivities of 10-6 m/sec for little fractured to 5x10-5 m/sec for intensely fractured rocks. Plug and rock sample data show that cataclastic fault rocks can have quite high porosities (up to 4.1%). However, plug permeabilities down to 0.03mD demonstrate that pores are too small to result in any significant permeability. Breccias show high porosities of 4% in average and very variable permeabilities between 2.2mD and 2214mD depending mainly on the degree of cementation.

Holocene Activity of the Enriquillo-Plantain Garden Fault in Lake Enriquillo Derived from Seismic Stratigraphy

NASA Astrophysics Data System (ADS)

Rios, J. K.; McHugh, C. M.; Hornbach, M. J.; Mann, P.; Wright, V. D.; Gurung, D.

2013-12-01

The Enriquillo-Plantain-Garden fault zone (EPGF) crosses Lake Enriquillo (LE) in the Dominican Republic and extends E-W across the southern peninsula of Haiti, south of the Baie de Port au Prince (BPP). Seismic stratigraphic studies of CHIRP high-resolution subbottom profiles calibrated to ages obtained from sediment cores and previous coral reef studies provide a Holocene record of relative sea level rise into the BPB and LE and a time frame for understanding tectonics of the EPGF. The BPP is 20 km wide, 20 km long, 150 m deep, and surrounded by coral reefs at water depths of 30 m. Three seismic units were identified: Unit 1: stepped terraces 5-10 m high. Laminated strata onlaps the terraces. This unit possibly represents Marine Isotope Stages 6 and 5, but has not been dated. Unit 2: laminated strata, thicker than 10 m and dated near its top at 22 ka BP. The microfossil assemblages reveal that during the latest Pleistocene sea level lowstand the BPP had a restricted connection with the global ocean. Few well-preserved marine microfossils are present and mostly are reworked. Geochemical analyses reveal that the laminated sediments were deposited during wet periods (>Si, Al wt %, Cu ppm) and dry periods (>Ca wt %). Unit 3: acoustically transparent, ~10 m thick, dated near its base and top at 14 ka BP and 2 ka BP, respectively. This unit represents the Holocene initiation of sea level rise and high stand containing well-preserved marine fossils. At ~9.5 ka BP planktonic foraminifers become abundant implying deepening of marine waters. Lake Enriquillo is 127 km east of the BPP. It is 15 km wide, 40 km long and 45 m deep. CHIRP subbottom profiles penetrated ~30 m below the lake floor. Four main acoustic units were identified: Unit 1: deformed basement with steeply dipping and folded beds. Based on land studies this unit is likely Plio-Pleistocene in age. Unit 2: laminated strata. Ages from coral reefs and deformed strata on land indicate this unit is likely pre-20 ka BP. Unit 3: acoustically transparent is 5-10 m thick. This unit shows top-lap terminations with the overlying strata and is interpreted as marine. Based on coral reef ages it was deposited during the Holocene 10 to 2 ka BP. Unit 4: laminated strata is ~ 5 m thick and downlaps offshore forming progradational packages. Pending Pb-210 ages from LE sediment cores a correlation between the two basins is proposed. During the latest Pleistocene sea level lowstand LE was separated from the BPP and the global ocean. The BPP was only partly connected to the sea. Sedimentation in both basins was dominated by wet and dry climate. The initial rise to high-stand of sea level into the BPP was at 14 ka BP. LE marine incursion was at 9.7 ka BP. At 2.8 ka BP LE became separated from the BPP possibly due to increased alluvial fan sedimentation. Evaporative conditions dominated the lake from 2.8 ka BP to the present and the lake waters lowered to ~43 m below sea level. We interpret the top laminated strata as deposited during the evaporative stage of the lake. Sediment progradation resulted from increased sedimentation due to lowering of base level. There is no evidence of tectonic activity in the BPP during the Holocene. In contrast, there are breaks in the Holocene strata in LE. So the EPGF is technically active across LE.

Revision of middle Proterozoic Yellowjacket Formation, central Idaho, and revision of Cretaceous Slim Sam Formation, Elkhorn mountains area, Montana

USGS Publications Warehouse

Tysdal, Russell G.

2000-01-01

The Yellowjacket Formation is restricted to the strata originally assigned to it by Ross (1934). The Yellowjacket, the conformably overlying Hoodoo Quartzite, and succeeding unnamed argillaceous quartzite unit form a genetically related sequence that lies in a structural block delimited on the northeast by the Iron Lake fault. Directly northeast of the fault, strata currently assigned by others to the lower subunit of the Yellowjacket are correlated with the Apple Creek Formation in the Lemhi Range. Mapping in the western part of the Lemhi Range shows that the Apple Creek Formation lies depositionally above the Big Creek Formation and that no rocks of the Yellowjacket-Hoodoo unnamed unit stratigraphic sequence are present. In contrast, in the area of the Yellowjacket mapped by Ross (1934) and the area directly northeast of the Iron Lake Fault, the Big Creek Formation is absent, even though it is 2,700 m thick in the Lemhi Range. These data indicate that the Iron Lake Fault juxtaposed the Yellowjacket-Hoodoo-unnamed unit sequence against non-Yellowjacket strata to the northeast. The Upper Cretaceous Slim Sam Formation of the Elkhorn Mountains area is revised. Strata of the lower part are correlated with the regionally recognized marine Telegraph Creek Formation and the overlying marine to marginal marine Eagle Sandstone. Only lower strata of the Eagle are present in the study area and they are preserved discontinously. The nonmarine volcanic and volcaniclastic rocks of the upper part of the Slim Sam as originally defined retain the name Slim Sam Formation. These rocks, mainly of sedimentary origin, are genetically related to the Elkhorn Mountains Volcanics. The lower contact of the Slim Sam (restricted) is unconformable above the Eagle Sandstone or more commonly above the Telegraph Creek Formation. The upper contact is conformable with the Elkhorn Mountains Volcanics.

A survey of benthic sediment contaminants in reaches of the Columbia River Estuary based on channel sedimentation characteristics.

PubMed

Counihan, Timothy D; Waite, Ian R; Nilsen, Elena B; Hardiman, Jill M; Elias, Edwin; Gelfenbaum, Guy; Zaugg, Steven D

2014-06-15

While previous studies have documented contaminants in fish, sediments, water, and wildlife, few specifics are known about the spatial distribution of contaminants in the Columbia River Estuary (CRE). Our study goal was to characterize sediment contaminant detections and concentrations in reaches of the CRE that were concurrently being sampled to assess contaminants in water, invertebrates, fish, and osprey (Pandion haliaetus) eggs. Our objectives were to develop a survey design based on sedimentation characteristics and then assess whether sediment grain size, total organic carbon (TOC), and contaminant concentrations and detections varied between areas with different sedimentation characteristics. We used a sediment transport model to predict sedimentation characteristics of three 16km river reaches in the CRE. We then compartmentalized the modeled change in bed mass after a two week simulation to define sampling strata with depositional, stable, or erosional conditions. We collected and analyzed bottom sediments to assess whether substrate composition, organic matter composition, and contaminant concentrations and detections varied among strata within and between the reaches. We observed differences in grain size fractions between strata within and between reaches. We found that the fine sediment fraction was positively correlated with TOC. Contaminant concentrations were statistically different between depositional vs. erosional strata for the industrial compounds, personal care products and polycyclic aromatic hydrocarbons class (Indus-PCP-PAH). We also observed significant differences between strata in the number of detections of Indus-PCP-PAH (depositional vs. erosional; stable vs. erosional) and for the flame retardants, polychlorinated biphenyls, and pesticides class (depositional vs. erosional, depositional vs. stable). When we estimated mean contaminant concentrations by reach, we observed higher contaminant concentrations in the furthest downstream reach with a decreasing trend in the two upstream reaches. Contaminant survey designs that account for sedimentation characteristics could increase the probability that sampling is allocated to areas likely to be contaminated. Published by Elsevier B.V.

Detrital zircon U-Pb geochronology of Cambrian to Triassic miogeoclinal and eugeoclinal strata of Sonora, Mexico

USGS Publications Warehouse

Gehrels, G.E.; Stewart, John H.

1998-01-01

One hundred and eighty two individual detrital zircon grains from Cambrian through Permian miogeoclinal strata, Ordovician eugeoclinal rocks, and Triassic post-orogenic sediments in northwestern Sonora have been analyzed. During Cambrian, Devonian, Permian, and Triassic time, most zircons accumulating along this part of the Cordilleran margin were shed from 1.40-1.45 and 1.62-1.78 Ga igneous rocks that are widespread in the southwestern United States and northwestern Mexico. Zircons with ages of approximately 1.11 Ga are common in Cambrian strata and were apparently shed from granite bodies near the sample site. The sources of 225-280 Ma zircons in our Triassic sample are more problematic, as few igneous rocks of these ages are recognized in northwestern Mexico. Such sources may be present but unrecognized, or the grains could have been derived from igneous rocks of the appropriate ages to the northwest in the Mojave Desert region, to the east in Chihuahua and Coahuila, or to the south in accreted(?) arc-type terranes. Because the zircon grains in our Cambrian and Devonian to Triassic samples could have accumulated in proximity to basement rocks near their present position or in the Death Valley region of southern California, our data do not support or refute the existence of the Mojave-Sonora megashear. Ordovician strata of both miogeoclinal and eugeoclinal affinity are dominated by >1.77 Ga detrital zircons, which are considerably older than most basement rocks in the region. Zircon grains in the miogeoclinal sample were apparently derived from the Peace River arch area of northwestern Canada and transported southward by longshore currents. The eugeoclinal grains may also have come from the Peace River arch region, with southward transport by either sedimentary or tectonic processes, or they may have been shed from off-shelf slivers of continents (perhaps Antarctica?) removed from the Cordilleran margin during Neoproterozoic rifting. It is also possible that the Ordovician eugeoclinal strata are far traveled and exotic to North America.

A newly discovered K-bentonite zone in the Lower Devonian of the Appalachian Basin; Basal Esopus and Needmore Formations (Late Pragian-Emsian)

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

Ver Straeten, C.A.

1992-01-01

The K-bentonite-rich interval of the Esopus Formation (eastern New York and northeastern Pennsylvania) overlies the coeval Oriskany/Glenerie/Ridgely Formations and ranges from 1 to 6.3 m in thickness. Six to seventeen soapy-feeling, yellow, tan, green, or gray clay to claystone beds (0.001 to 0.5 m-thick) interbedded with thin siltstone and chert beds (0.02--1 m-thick) characterize outcrops in eastern New York. Heavy mineral separates from these layers yield abundant uncorraded euhedral zircons and apatites, indicating that these are K-bentonites. In eastern Pennsylvania, the westernmost outcrop of the Esopus Formation displays a 2.3 m-thick massive, soapy-feeling clay to claystone-dominated interval. The presence ofmore » both coarse, highly abraded and small, fragile, pristine-appearing zircons and apatites from a 20 cm sampled interval may indicate a complex amalgamation/reworking history to the relatively thick, clay-dominated strata. Similar clay/claystone-rich strata have been found in the lower 0.15 to 1 m of the Beaverdam Member (Needmore Formation) in central Pennsylvania. Interbedded clays and claystones with or without minor siltstone beds characterize some outcrops. Other localities are clay-dominated, with minor amounts of quartz sand present in strata immediately overlying the Ridgely Sandstone. These newly discovered K-bentonite-rich strata mark a transition from shelfal orthoquartzites and carbonates to basinal black/dark gray shales similar to the overlying Middle Devonian Tioga ash interval. Deposition of ash-rich strata, associated with increased volcanic activity, coincided with subsidence of the foreland basin/relative sea level rise. These events were concurrent with a flush of siliciclastic sediments into the basin and are indicative of the onset of an early tectophase of the Devonian Acadian Orogeny.« less

Preliminary numerical simulation for shallow strata stability of coral reef in South China Sea

NASA Astrophysics Data System (ADS)

Tang, Qinqin; Zhan, Wenhuan; Zhang, Jinchang

2017-04-01

Coral reefs are the geologic material and special rock and soil, which live in shallow water of the tropic ocean and are formed through biological and geological action. Since infrastructure construction is being increasingly developed on coral reefs during recent years, it is necessary to evaluate the shallow strata stability of coral reefs in the South China Sea. The paper is to study the borehole profiles for shallow strata of coral reefs in the South China Sea, especially in the hydrodynamic marine environment?, and to establish a geological model for numerical simulation with Geo-Studio software. Five drilling holes show a six-layer shallow structure of South China Sea, including filling layer, mid-coarse sand, coral sand gravel, fine sand, limestone debris and reef limestone. The shallow coral reef profile next to lagoon is similar to "layers cake", in which the right side close to the sea is analogous to "block cake". The simulation results show that coral reef stability depends on wave loads and earthquake strength, as well as the physical properties of coral reefs themselves. The safety factor of the outer reef is greater than 10.0 in the static condition, indicating that outer reefs are less affected by the wave and earthquake. However, the safety factor next to lagoon is ranging from 0.1 to 4.9. The main reason for the variations that the strata of coral reefs close to the sea are thick. For example, the thickness of reef limestone is more than 10 m and equivalent to the block. When the thickness of inside strata is less than 10 m, they show weak engineering geological characteristics. These findings can provide useful information for coral reef constructions in future. This work was funded by National Basic Research Program of China (contract: 2013CB956104) and National Natural Science Foundation of China (contract: 41376063).

Modelling of Longwall Mining-Induced Strata Permeability Change

NASA Astrophysics Data System (ADS)

Adhikary, D. P.; Guo, H.

2015-01-01

The field measurement of permeability within the strata affected by mining is a challenging and expensive task, thus such tests may not be carried out in large numbers to cover all the overburden strata and coal seams being affected by mining. However, numerical modelling in conjunction with a limited number of targeted field measurements can be used efficiently in assessing the impact of mining on a regional scale. This paper presents the results of underground packer testing undertaken at a mine site in New South Wales in Australia and numerical simulations conducted to assess the mining-induced strata permeability change. The underground packer test results indicated that the drivage of main headings (roadways) had induced a significant change in permeability into the solid coal barrier. Permeability increased by more than 50 times at a distance of 11.2-11.5 m from the roadway rib into the solid coal barrier. The tests conducted in the roof strata above the longwall goaf indicated more than 1,000-fold increase in permeability. The measured permeability values varied widely and strangely on a number of occasions; for example the test conducted from the main headings at the 8.2-8.5 m test section in the solid coal barrier showed a decline in permeability value as compared to that at the 11.2-11.5 m section contrary to the expectations. It is envisaged that a number of factors during the tests might have had affected the measured values of permeability: (a) swelling and smearing of the borehole, possibly lowering the permeability values; (b) packer bypass by larger fractures; (c) test section lying in small but intact (without fractures) rock segment, possibly resulting in lower permeability values; and (d) test section lying right at the extensive fractures, possibly measuring higher permeability values. Once the anomalous measurement data were discarded, the numerical model results could be seen to match the remaining field permeability measurement data reasonably well.

Stature signals status: The association of stature, status and perceived dominance - a thought experiment.

PubMed

Hermanussen, Michael; Scheffler, Christiane

2016-11-01

Background: There is a common perception that tall stature results in social dominance. Evidence in meerkats suggests that social dominance itself may be a strong stimulus for growth. Relative size serves as the signal for individuals to induce strategic growth adjustments . Aim: We construct a thought experiment to explore the potential consequences of the question: is stature a social signal also in humans? We hypothesize that (1) upward trends in height in the lower social strata are perceived as social challenges yielding similar though attenuated upward trends in the dominant strata, and that (2) democratization, but also periods of political turmoil that facilitate upward mobility of the lower strata, are accompanied by upward trends in height. Material and methods: We reanalyzed large sets of height data of European conscripts born between 1856-1860 and 1976-1980; and annual data of German military conscripts, born between 1965 and 1985, with information on height and school education. Results: Taller stature is associated with higher socioeconomic status. Historic populations show larger height differences between social strata that tend to diminish in the more recent populations. German height data suggest that both democratization, and periods of political turmoil facilitating upward mobility of the lower social strata are accompanied by a general upward height spiral that captures the whole population. Discussion: We consider stature as a signal. Nutrition, health, general living conditions and care giving are essential prerequisites for growth, yet not to maximize stature, but to allow for its function as a lifelong social signal. Considering stature as a social signal provides an elegant explanation of the rapid height adjustments observed in migrants, of the hitherto unexplained clustering of body height in modern and historic cohorts of military conscripts, and of the parallelism between changes in political conditions, and secular trends in adult human height since the 19 th century.

Specialization and interaction strength in a tropical plant-frugivore network differ among forest strata.

PubMed

Schleuning, Matthias; Blüthgen, Nico; Flörchinger, Martina; Braun, Julius; Schaefer, H Martin; Böhning-Gaese, Katrin

2011-01-01

The degree of interdependence and potential for shared coevolutionary history of frugivorous animals and fleshy-fruited plants are contentious topics. Recently, network analyses revealed that mutualistic relationships between fleshy-fruited plants and frugivores are mostly built upon generalized associations. However, little is known about the determinants of network structure, especially from tropical forests where plants' dependence on animal seed dispersal is particularly high. Here, we present an in-depth analysis of specialization and interaction strength in a plant-frugivore network from a Kenyan rain forest. We recorded fruit removal from 33 plant species in different forest strata (canopy, midstory, understory) and habitats (primary and secondary forest) with a standardized sampling design (3447 interactions in 924 observation hours). We classified the 88 frugivore species into guilds according to dietary specialization (14 obligate, 28 partial, 46 opportunistic frugivores) and forest dependence (50 forest species, 38 visitors). Overall, complementary specialization was similar to that in other plant-frugivore networks. However, the plant-frugivore interactions in the canopy stratum were less specialized than in the mid- and understory, whereas primary and secondary forest did not differ. Plant specialization on frugivores decreased with plant height, and obligate and partial frugivores were less specialized than opportunistic frugivores. The overall impact of a frugivore increased with the number of visits and the specialization on specific plants. Moreover, interaction strength of frugivores differed among forest strata. Obligate frugivores foraged in the canopy where fruit resources were abundant, whereas partial and opportunistic frugivores were more common on mid- and understory plants, respectively. We conclude that the vertical stratification of the frugivore community into obligate and opportunistic feeding guilds structures this plant-frugivore network. The canopy stratum comprises stronger links and generalized associations, whereas the lower strata are composed of weaker links and more specialized interactions. Our results suggest that seed-dispersal relationships of plants in lower forest strata are more prone to disruption than those of canopy trees.

A survey of benthic sediment contaminants in reaches of the Columbia River Estuary based on channel sedimentation characteristics

USGS Publications Warehouse

Counihan, Timothy D.; Waite, Ian R.; Nilsen, Elena B.; Hardiman, Jill M.; Elias, Edwin; Gelfenbaum, Guy; Zaugg, Steven D.

2014-01-01

While previous studies have documented contaminants in fish, sediments, water, and wildlife, few specifics are known about the spatial distribution of contaminants in the Columbia River Estuary (CRE). Our study goal was to characterize sediment contaminant detections and concentrations in reaches of the CRE that were concurrently being sampled to assess contaminants in water, invertebrates, fish, and osprey (Pandion haliaetus) eggs. Our objectives were to develop a survey design based on sedimentation characteristics and then assess whether sediment grain size, total organic carbon (TOC), and contaminant concentrations and detections varied between areas with different sedimentation characteristics. We used a sediment transport model to predict sedimentation characteristics of three 16 km river reaches in the CRE. We then compartmentalized the modeled change in bed mass after a two week simulation to define sampling strata with depositional, stable, or erosional conditions. We collected and analyzed bottom sediments to assess whether substrate composition, organic matter composition, and contaminant concentrations and detections varied among strata within and between the reaches. We observed differences in grain size fractions between strata within and between reaches. We found that the fine sediment fraction was positively correlated with TOC. Contaminant concentrations were statistically different between depositional vs. erosional strata for the industrial compounds, personal care products and polycyclic aromatic hydrocarbons class (Indus–PCP–PAH). We also observed significant differences between strata in the number of detections of Indus–PCP–PAH (depositional vs. erosional; stable vs. erosional) and for the flame retardants, polychlorinated biphenyls, and pesticides class (depositional vs. erosional, depositional vs. stable). When we estimated mean contaminant concentrations by reach, we observed higher contaminant concentrations in the furthest downstream reach with a decreasing trend in the two upstream reaches. Contaminant survey designs that account for sedimentation characteristics could increase the probability that sampling is allocated to areas likely to be contaminated.

Devonian salt dissolution-collapse breccias flooring the Cretaceous Athabasca oil sands deposit and development of lower McMurray Formation sinkholes, northern Alberta Basin, Western Canada

NASA Astrophysics Data System (ADS)

Broughton, Paul L.

2013-01-01

The sub-Cretaceous paleotopography underlying giant Lower Cretaceous Athabasca oil sands, northern Alberta, has an orthogonal lattice pattern of troughs up to 50 km long and 100 m deep between pairs of cross-cutting lineaments. These structures are interpreted to have been inherited from a similar pattern of dissolution collapse-subsidence troughs in the underlying Middle Devonian salt beds. Removal of more than 100 m of halite salt fragmented the overlying Upper Devonian strata into fault blocks and collapse breccias that subsided into the underlying dissolution troughs. The unusually low 1:2 to 1:3 thickness ratios of halite salts to the overlying strata resulted in the Upper Devonian strata collapse-subsidence into underlying salt dissolution troughs being more cataclysmic during the first phase of salt removal. The second phase of slower but complete salt removal between the earlier troughs resulted in a more gradual subsidence of the overlying strata. This obliterated the earlier pattern of giant cross-cutting dissolution troughs bounded by major lineaments. The collapse breccia fabrics underlying the earlier troughs differ from those from areas between the troughs. Collapse breccias underlying the large troughs often have crushed fabrics distributed in zones that rapidly pinched out between fault blocks. Breccias between troughs developed as giant mosaics of detached carbonate blocks that formed breccia pipe complexes. Multiple sinkholes up to 100 m deep aligned along multi-km linear valley trends that dissected the sub-Cretaceous paleotopography. These sinkhole trends formed orthogonal patterns inherited from underlying lattice of NW-SE and NE-SW salt structured lineaments. These cross-cutting sinkhole trends have a smaller 5 km scale reticulate pattern similar to the giant 50 km scale pattern of collapse-subsidence troughs. Other sinkholes developed as lower McMurray strata sagged when underlying Devonian fault blocks and breccia pipes differentially subsided.

Eastgate Geothermal Borehole Project: Predicting Fracture Geometry at Depth

NASA Astrophysics Data System (ADS)

Beattie, Stewart; Shipton, Zoe K.; Johnson, Gareth; Younger, Paul L.

2013-04-01

In 2004 an exploratory borehole at the Eastgate Geothermal Project encountered part of a vein system within the Weardale granite. At 995m depth brine was at a temperature of around 46°C. The geothermal source is likely related to the Slitt vein system that cuts through c.270m of carboniferous sedimentary strata overlying the Weardale granite pluton. The economic success of the Eastgate geothermal project is dependent on exploiting this vein system in an otherwise low permeability and low geothermal gradient setting. The Slitt vein system has been extensively mined. Mining records show the attitude of the vein through the sedimentary strata, however, the trajectory and magnitude of the vein within the pluton itself is unknown. Using mine records, geological maps and published literature, models of the vein system up to the depth of the pluton were created. To extend this model into the pluton itself requires some knowledge regarding the geometry and evolution of the pluton and subsequently properties of vein systems and other fracture populations at depth. The properties of fracture and vein populations within the granite will depend on forming processes including; cooling and contraction of the pluton, deformation of host rocks during pluton emplacement, and post emplacement deformation. Using published literature and gravity data a 3D model of the geometry of the pluton was constructed. Shape analysis of the pluton allows an estimation of the orientation of fractures within the pluton. Further modelling of the structural evolution of the pluton will enable kinematic or geomechanical strain associated with the structural evolution to be captured and subsequently used as a proxy for modelling both intensity and orientation of fracturing within the pluton. The successful prediction of areas of high fracture intensity and thus increased permeability is critical to the development of potential geothermal resources in low geothermal gradient and low permeability settings. This is also important in EGS settings where stimulation will often re-activate existing fracture networks. The development at the Eastgate Geothermal Borehole project provides an opportunity to model fracture and vein populations within an intrusive body and validate those model predictions with production data from the site.

Structural plays in Ellesmerian sequence and correlative strata of the National Petroleum Reserve, Alaska

USGS Publications Warehouse

Moore, Thomas E.; Potter, Christopher J.

2003-01-01

Reservoirs in deformed rocks of the Ellesmerian sequence in southern NPRA are assigned to two hydrocarbon plays, the Thrust-Belt play and the Ellesmerian Structural play. The two plays differ in that the Thrust-Belt play consists of reservoirs located in allochthonous strata in the frontal part of the Brooks Range fold-and-thrust belt, whereas those of the Ellesmerian Structural play are located in autochthonous or parautochthonous strata at deeper structural levels north of the Thrust-Belt play. Together, these structural plays are expected to contain about 3.5 TCF of gas but less than 6 million barrels of oil. These two plays are analyzed using a two-stage deformational model. The first stage of deformation occurred during the Neocomian, when distal strata of the Ellesmerian sequence were imbricated and assembled into deformational wedges emplaced northward onto regionally south-dipping authochon at 140-120 Ma. In the mid-Cretaceous following cessation of the deformation, the Colville basin, the foreland basin to the orogen, was filled with a thick clastic succession. During the second stage of deformation at about 60 Ma (early Tertiary), the combined older orogenic belt-foreland basin system was involved in another episode of north-vergent contractional deformation that deformed pre-existing stratigraphic and structurally trapped reservoir units, formed new structural traps, and caused significant amounts of uplift, although the amount of shortening was relatively small in comparison to the first episode of deformation. Hydrocarbon generation from source strata (Shublik Formation, Kingak Shale, and Otuk Formation) and migration into stratigraphic traps occurred primarily by sedimentary burial principally between 100-90 Ma, between the times of the two episodes of deformation. Subsequent burial caused deep stratigraphic traps to become overmature, cracking oil to gas, and some new generation to begin progressively higher in the section. Structural disruption of the traps in the Early Tertiary is hypothesized to have released sequestered hydrocarbons and caused remigration into newly formed structural traps formed at higher structural levels. Because of the generally high maturation of the Colville basin at the time of the deformation and remigration, most of the hydrocarbons available to fill traps were gas. In the the Thrust-Belt play, the primary reservoir lithology is expected to be dolomitic carbonate rocks of the Lisburne Group, which contain up to 15% porosity. Antiformal stacks of imbricated Lisburne Group strata form the primary trapping configuration, with chert and shale of the overlying Etivluk Group forming seals on closures. Traps are expected to have been charged primarily with remigrated gas, but oil generated from local sources in the Otuk Formation may have filled some traps at high structural levels. The timing for migration of gas into traps is excellent, but only moderate for oil because peak oil generation for the play as a whole occurred 30 to 40 m.y. before trap formation. Reservoir and seal quality in the play are questionable, reducing the likelyhood of hydrocarbon accumulations being present in the play. Our analysis suggests that the play will hold 5.7 million barrels of technically recoverable oil and 1.5 TCF gas (mean values). In the Ellesmerian Stuctural play, the primary reservoir lithologies will be dolomitic carbonate rocks of the Lisburne Group and, less likely, clastic units in the Ellesmerian sequence. Traps in the play are anticlinal closures caused by small amounts of strain in the footwall below the basal detachment for most early Tertiary thrusting. Because these traps lie beneath the main source rock units (Shublik, Kingak, lower Brookian sequence), reservoirs that are juxtaposed by faulting against source-rock units are expected to have the most favorable migration pathways. The charge will be primarily remigrated gas; no oil is expected because of the great depths (15,000 to 26,000 ft) and consequent high thermal maturity of this play. Although the the probability of charge and timeliness of trap formation and gas remigration are excellent, seal and reservoir qualities are anticipated to be poor. Our analysis suggests that about 2.0 TCF of techncially recoverable gas can be expected in the play.

Do Mice Habituate to “Gentle Handling?” A Comparison of Resting Behavior, Corticosterone Levels and Synaptic Function in Handled and Undisturbed C57BL/6J Mice

PubMed Central

Longordo, Fabio; Fan, Jing; Steimer, Thierry; Kopp, Caroline; Lüthi, Anita

2011-01-01

Study Objectives: “Gentle handling” has become a method of choice for 4-6 h sleep deprivation in mice, with repeated brief handling applied before sleep deprivation to induce habituation. To verify whether mice do indeed habituate, we assess how 6 days of repeated brief handling impact on resting behavior, on stress, and on the subunit content of N-methyl-D-aspartate receptors (NMDARs) at hippocampal synapses, which is altered by sleep loss. We discuss whether repeated handling biases the outcome of subsequent sleep deprivation. Design: Adult C57BL/6J mice, maintained on a 12 h-12 h light-dark cycle, were left undisturbed for 3 days, then handled during 3 min daily for 6 days in the middle of the light phase. Mice were continuously monitored for their resting time. Serum corticosterone levels and synaptic NMDAR subunit composition were quantified. Results: Handling caused a ∼25% reduction of resting time throughout all handling days. After six, but not after one day of handling, mice had elevated serum corticosterone levels. Six-day handling augmented the presence of the NR2A subunit of NMDARs at hippocampal synapses. Conclusion: Repeated handling induces behavioral and neurochemical alterations that are absent in undisturbed animals. The persistently reduced resting time and the delayed increase in corticosterone levels indicate that mice do not habituate to handling over a 1-week period. Handling-induced modifications bias effects of gentle handling-induced sleep deprivation on sleep homeostasis, stress, glutamate receptor composition and signaling. A standardization of sleep deprivation procedures involving gentle handling will be important for unequivocally specifying how acute sleep loss affects brain function. Citation: Longordo F; Fan J; Steimer T; Kopp C; Lüthi A. Do mice habituate to “gentle handling?” A comparison of resting behavior, corticosterone levels and synaptic function in handled and undisturbed C57BL/6J mice. SLEEP 2011;34(5):679-681. PMID:21532962

Cultural Resource Reconnaissance of U.S. Army Corps of Engineers Land Alongside Lake Sakakawea in Dunn County, North Dakota. Volume 1. Main Report

DTIC Science & Technology

1987-11-01

and depth: Depression is 200cm in depth. Vegetation: Pasture/short grass. Depression full of chokecherries and trees. Ground surface visibility...Strata and depth: Unknown - likely 0-10cm. Vegetation: Dwarf juniper and chokecherry (Locus 1) and bunch grass and ball cactus (Locus 2). Ground surface...position: On the NE edge of a long, narrow ridge/erosional remnant or bluff. Site size: 6m2. Strata and depth: Unknown. Vegetation: Buckbrush, chokecherry

Demolition and removal of radioactively contaminated concrete soil: Aerosol control and monitoring

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

Newton, G.J.; Hoover, M.D.; Grace, A.C. III

1995-12-01

From 1963 to 1985, two concrete-lined ponds were used to reduce the volume of radioactive liquids from the Institute`s research programs. Following withdrawal of the {open_quotes}hot ponds{close_quotes} from active use, the residual sludges and plastic liners of the ponds were removed and shipped to a radioactive waste disposal site. From 1987 to 1994, the concrete structures remained undisturbed pending environmental restoration on the site. Restoration began in 1994 and was completed in 1995. Restoration involved mechanical breakup and removal of the concrete structures and removal of areas of contaminated soils from the site. This report describes the design and resultsmore » of the aerosol control and monitoring program that was conducted to ensure protection of workers and the environment during the restoration process. The aerosol control and monitoring strategy developed for remediation of the ITRI hot ponds was successful both in preventing dispersion of radioactive dusts and in demonstrating that exposures of workers and offsite releases were within statutory limits.« less

Floristic and vegetation successional processes within landslides in a Mediterranean environment.

PubMed

Neto, Carlos; Cardigos, Patrícia; Oliveira, Sérgio Cruz; Zêzere, José Luís

2017-01-01

Floristic and vegetation analysis in seven Mediterranean landslides led to the understanding of the successional processes occurring in different landslide disturbed sectors. Our study showed that in landslides that occurred between 1996 and 2010 there is a clear differentiation between the three main landslide sectors (scarp, main body and foot) concerning floristic composition, vegetation structure, floristic richness, successional processes and plant functional type. Additional differences were found between landslide areas and undisturbed agricultural areas adjacent to landslides. In this study 48 floristic relevés were made using a stratified random sampling design. The main landslide body exhibits the highest floristic richness whereas the landslide scarp has the lowest coverage rate and the highest presence of characteristic species from ruderal and strongly perturbed habitats. Finally, the landslide foot shows a late stage in the succession (maquis or pre-forest stage) with a high dominance of vines. We further discuss the importance of landslides as reservoirs of biodiversity especially for Mediterranean orchids. Copyright © 2016 Elsevier B.V. All rights reserved.

Factors influencing depredation of artificial duck nests

USGS Publications Warehouse

Esler, Daniel N.; Grand, James B.

1993-01-01

Because artificial nests can facilitate controlled experiments of nest success, we used them to assess whether human visitation, nest density, vegetation structure, and proximity to habitat edge could affect depredation of duck nests on Yukon Flats National Wildlife Refuge, Alaska. More (P < 0.01) nests in a plot visited daily (100%) were depredated than those in plots visited at intervals of 7 (40%), 14 (35%), or 28 days (45%). More (P < 0.01) nests were depredated in a plot with 10 nests/ha (95%) than nests in a plot of a lower density (2/ha; 40%). Vegetation height, vegetation density, distance to a wetland, distance to forest edge, or distance to the nearest ecotone did not differ (P > 0.05) between depredated and undisturbed nests. We suggest that daily visitation of duck nests increases depredation, but longer intervals, typical of most nest studies, do not. High nesting densities, which could occur when flooding limits nesting habitat, may result in higher depredation rates.

Molluscan indicator species and their potential use in ecological status assessment using species distribution modeling.

PubMed

Moraitis, Manos L; Tsikopoulou, Irini; Geropoulos, Antonios; Dimitriou, Panagiotis D; Papageorgiou, Nafsika; Giannoulaki, Marianna; Valavanis, Vasilis D; Karakassis, Ioannis

2018-05-24

Marine habitat assessment using indicator species through Species Distribution Modeling (SDM) was investigated. The bivalves: Corbula gibba and Flexopecten hyalinus were the indicator species characterizing disturbed and undisturbed areas respectively in terms of chlorophyll a concentration in Greece. The habitat suitability maps of these species reflected the overall ecological status of the area. The C. gibba model successfully predicted the occurrence of this species in areas with increased physical disturbance driven by chlorophyll a concentration, whereas the habitat map for F. hyalinus showed an increased probability of occurrence in chlorophyll-poor areas, affected mainly by salinity. We advocate the use of C. gibba as a proxy for eutrophication and the incorporation of this species in monitoring studies through SDM methods. For the Mediterranean Sea we suggest the use of F. hyalinus in SDM as an indicator of environmental stability and a possible forecasting tool for salinity fluctuations. Copyright © 2018 Elsevier Ltd. All rights reserved.

Prediction of compressibility parameters of the soils using artificial neural network.

PubMed

Kurnaz, T Fikret; Dagdeviren, Ugur; Yildiz, Murat; Ozkan, Ozhan

2016-01-01

The compression index and recompression index are one of the important compressibility parameters to determine the settlement calculation for fine-grained soil layers. These parameters can be determined by carrying out laboratory oedometer test on undisturbed samples; however, the test is quite time-consuming and expensive. Therefore, many empirical formulas based on regression analysis have been presented to estimate the compressibility parameters using soil index properties. In this paper, an artificial neural network (ANN) model is suggested for prediction of compressibility parameters from basic soil properties. For this purpose, the input parameters are selected as the natural water content, initial void ratio, liquid limit and plasticity index. In this model, two output parameters, including compression index and recompression index, are predicted in a combined network structure. As the result of the study, proposed ANN model is successful for the prediction of the compression index, however the predicted recompression index values are not satisfying compared to the compression index.

Study on Strata Behavior Regularity of 1301 Face in Thick Bedrock of Wei - qiang Coal Mine

NASA Astrophysics Data System (ADS)

Gu, Shuancheng; Yao, Boyu

2017-09-01

In order to ensure the safe and efficient production of the thick bedrock face, the rule of the strata behavior of the thick bedrock face is discussed through the observation of the strata pressure of the 1301 first mining face in Wei qiang coal mine. The initial face is to press the average distance of 50.75m, the periodic weighting is to press the average distance of 12.1m; during the normal mining period, although the upper roof can not be broken at the same time, but the pressure step is basically the same; the working face for the first weighting and periodical weighting is more obvious to the change of pressure step change, when the pressure of the working face is coming, the stent force increased significantly, but there are still part of the stent work resistance exceeds the rated working resistance, low stability, still need to strengthen management.

Sensitive strata in Bootlegger Cove Formation

USGS Publications Warehouse

Olsen, Harold W.

1989-01-01

Sensitivity magnitudes are interpreted from remolded strength values in recent subsurface geologic, geotechnical, and geochemical data from the Bootlegger Cove Formation adjacent to the Turnagain Heights Landslide. The results show that strata composed of highly sensitive clays occur in both the middle and lower zones of the formation, and that between these strata the clays are generally of low-to-medium sensitivity. The most sensitive stratum is in the middle zone between two sand layers, and its sensitivity increases from both clay-sand interfaces to a maximum at the center of the stratum. The pore fluid chemistry of the highly sensitive materials differs from that in the materials of low to medium sensitivity only in their concentrations of organic carbon, chloride, bicarbonate, and sulfate. The total dissolved solids concentration is low, and the ratio of monovalent to divalent cations is very high throughout the middle and lower zones of the formation. Of the known causes of high and extremely high sensitivities, only organic and/or anionic dispersants are consistent with these findings.

Landsat image and sample design for water reservoirs (Rapel dam Central Chile).

PubMed

Lavanderos, L; Pozo, M E; Pattillo, C; Miranda, H

1990-01-01

Spatial heterogeneity of the Rapel reservoir surface waters is analyzed through Landsat images. The image digital counts are used with the aim or developing an aprioristic quantitative sample design.Natural horizontal stratification of the Rapel Reservoir (Central Chile) is produced mainly by suspended solids. The spatial heterogeneity conditions of the reservoir for the Spring 86-Summer 87 period were determined by qualitative analysis and image processing of the MSS Landsat, bands 1 and 3. The space-time variations of the different observed strata obtained with multitemporal image analysis.A random stratified sample design (r.s.s.d) was developed, based on the digital counts statistical analysis. Strata population size as well as the average, variance and sampling size of the digital counts were obtained by the r.s.s.d method.Stratification determined by analysis of satellite images were later correlated with ground data. Though the stratification of the reservoir is constant over time, the shape and size of the strata varys.

Subgrade characterization for highway pavement design.

DOT National Transportation Integrated Search

2000-12-01

Subgrade soil characterization expressed in terms of Resilient Modulus (MR) has become crucial for pavement design. For a new design, MR : values are generally obtained by conducting repeated triaxial tests on reconstituted/undisturbed cylindrical sp...

Simulation of a hydrocarbon fueled scramjet exhaust

NASA Technical Reports Server (NTRS)

Leng, J.

1982-01-01

Exhaust nozzle flow fields for a fully integrated, hydrocarbon burning scramjet were calculated for flight conditions of M (undisturbed free stream) = 4 at 6.1 km altitude and M (undisturbed free stream) = 6 at 30.5 km altitude. Equilibrium flow, frozen flow, and finite rate chemistry effects are considered. All flow fields were calculated by method of characteristics. Finite rate chemistry results were evaluated by a one dimensional code (Bittker) using streamtube area distributions extracted from the equilibrium flow field, and compared to very slow artificial rate cases for the same streamtube area distribution. Several candidate substitute gas mixtures, designed to simulate the gas dynamics of the real engine exhaust flow, were examined. Two mixtures are found to give excellent simulations of the specified exhaust flow fields when evaluated by the same method of characteristics computer code.

Misrepresentation of hydro-erosional processes in rainfall simulations using disturbed soil samples

NASA Astrophysics Data System (ADS)

Thomaz, Edivaldo L.; Pereira, Adalberto A.

2017-06-01

Interrill erosion is a primary soil erosion process which consists of soil detachment by raindrop impact and particle transport by shallow flow. Interill erosion affects other soil erosion sub-processes, e.g., water infiltration, sealing, crusting, and rill initiation. Interrill erosion has been widely studied in laboratories, and the use of a sieved soil, i.e., disturbed soil, has become a standard method in laboratory experiments. The aims of our study are to evaluate the hydro-erosional response of undisturbed and disturbed soils in a laboratory experiment, and to quantify the extent to which hydraulic variables change during a rainstorm. We used a splash pan of 0.3 m width, 0.45 m length, and 0.1 m depth. A rainfall simulation of 58 mm h- 1 lasting for 30 min was conducted on seven replicates of undisturbed and disturbed soils. During the experiment, several hydro-physical parameters were measured, including splashed sediment, mean particle size, runoff, water infiltration, and soil moisture. We conclude that use of disturbed soil samples results in overestimation of interrill processes. Of the nine assessed parameters, four displayed greater responses in the undisturbed soil: infiltration, topsoil shear strength, mean particle size of eroded particles, and soil moisture. In the disturbed soil, five assessed parameters displayed greater responses: wash sediment, final runoff coefficient, runoff, splash, and sediment yield. Therefore, contextual soil properties are most suitable for understanding soil erosion, as well as for defining soil erodibility.

Analysis of morphological variability and heritability in the head of the Argentine Black and White Tegu (Salvator merianae): undisturbed vs. disturbed environments.

PubMed

Imhoff, Carolina; Giri, Federico; Siroski, Pablo; Amavet, Patricia

2018-04-01

The heterogeneity of biotic and abiotic factors influencing fitness produce selective pressures that promote local adaptation and divergence among different populations of the same species. In order for adaptations to be maintained through evolutionary time, heritable genetic variation controlling the expression of the morphological features under selection is necessary. Here we compare morphological shape variability and size of the cephalic region of Salvator merianae specimens from undisturbed environments to those of individuals from disturbed environments, and estimated heritability for shape and size using geometric morphometric and quantitative genetics tools. The results of these analyzes indicated that there are statistically significant differences in shape and size between populations from the two environments. Possibly, one of the main determinants of cephalic shape and size is adaptation to the characteristics of the environment and to the trophic niche. Individuals from disturbed environments have a cephalic region with less shape variation and also have a larger centroid size when compared to individuals from undisturbed environments. The high heritability values obtained for shape and size in dorsal view and right side view indicate that these phenotypic characters have a great capacity to respond to the selection pressures to which they are subjected. Data obtained here could be used as an important tool when establishing guidelines for plans for the sustainable use and conservation of S. merianae and other species living in disturbed areas. Copyright © 2018 Elsevier GmbH. All rights reserved.

[Dynamic changes of landscape pattern and hemeroby in Ximen Island wetland, Zhejiang Province, China].

PubMed

Xiao, Cui; Xie, Xue-Fen; Wu, Tao; Jiang, Guo-Jun; Bian, Hua-Jing; Xu, Wei

2014-11-01

Abstract: The hemeroby type classification system of Ximen Island wetland of Zhejiang Province was established based on the multiple datasets: SOPT-5 image data with a spatial resolution of 5 m in 2007 and 2010, its wetland land cover and land use status, the National Land Use Classification (on trail), and sea area use classification of marine industry standards as well as remote sensing data features. Meanwhile, the dynamic relationship between the landscape pattern and the degree of hemeroby in Ximen Island was investigated with the landscape indices and hemeroby index (HI) derived from the landscape pattern index and GIS spatial analysis. The results showed that the wetland landscape spatial heterogeneity, fragmentation and dominance index dropped, and the landscape shape index complexity was low. The human disturbance center developed from a dispersion type to a concentration type. The landscape type of the disturbance center was bare land and settlement. The HI rose up from the sea to the land. Settlement, wharf and traffic land had the highest HI. The HI of the mudflat cultivation, mudflats and raft-cultivation dramatically changed. Marine-terrestrial interlaced zone showed a low total HI with unstable characteristics. The number of patches declined of undisturbed, partially disturbed and completely disturbed landscapes. Mean patch areas of partially disturbed and completely disturbed landscapes increased, and that of the undisturbed decreased. Mean shape index of the undisturbed landscape decreased, while the partially disturbed and completely disturbed landscapes showed a trend of shape complication.

Permafrost thaw and intense thermokarst activity decreases abundance of stream benthic macroinvertebrates.

PubMed

Chin, Krista S; Lento, Jennifer; Culp, Joseph M; Lacelle, Denis; Kokelj, Steven V

2016-08-01

Intensification of permafrost thaw has increased the frequency and magnitude of large permafrost slope disturbances (mega slumps) in glaciated terrain of northwestern Canada. Individual thermokarst disturbances up to 40 ha in area have made large volumes of previously frozen sediments available for leaching and transport to adjacent streams, significantly increasing sediment and solute loads in these systems. To test the effects of this climate-sensitive disturbance regime on the ecology of Arctic streams, we explored the relationship between physical and chemical variables and benthic macroinvertebrate communities in disturbed and undisturbed stream reaches in the Peel Plateau, Northwest Territories, Canada. Highly disturbed and undisturbed stream reaches differed with respect to taxonomic composition and invertebrate abundance. Minimally disturbed reaches were not differentiated by these variables but rather were distributed along a disturbance gradient between highly disturbed and undisturbed sites. In particular, there was evidence of a strong negative relationship between macroinvertebrate abundance and total suspended solids, and a positive relationship between abundance and the distance from the disturbance. Increases in both sediments and nutrients appear to be the proximate cause of community differences in highly disturbed streams. Declines in macroinvertebrate abundance in response to slump activity have implications for the food webs of these systems, potentially leading to negative impacts on higher trophic levels, such as fish. Furthermore, the disturbance impacts on stream health can be expected to intensify as climate change increases the frequency and magnitude of thermokarst. © 2016 John Wiley & Sons Ltd.

Documentation of a numerical code for the simulation of variable density ground-water flow in three dimensions

USGS Publications Warehouse

Kuiper, L.K.

1985-01-01

A numerical code is documented for the simulation of variable density time dependent groundwater flow in three dimensions. The groundwater density, although variable with distance, is assumed to be constant in time. The Integrated Finite Difference grid elements in the code follow the geologic strata in the modeled area. If appropriate, the determination of hydraulic head in confining beds can be deleted to decrease computation time. The strongly implicit procedure (SIP), successive over-relaxation (SOR), and eight different preconditioned conjugate gradient (PCG) methods are used to solve the approximating equations. The use of the computer program that performs the calculations in the numerical code is emphasized. Detailed instructions are given for using the computer program, including input data formats. An example simulation and the Fortran listing of the program are included. (USGS)

Cyclothem [“digital”] correlation and biostratigraphy across the global Moscovian-Kasimovian-Gzhelian stage boundary interval (Middle-Upper Pennsylvanian) in North America and eastern Europe

NASA Astrophysics Data System (ADS)

Heckel, Philip H.; Alekseev, Aleksandr S.; Barrick, James E.; Boardman, Darwin R.; Goreva, Natalya V.; Nemyrovska, Tamara I.; Ueno, Katsumi; Villa, Elisa; Work, David M.

2007-07-01

The long-standing difficulty of correlating Pennsylvanian strata among provincial faunal regions is resolved by effecting “digital” correlation of major glacial-eustatic cyclothems that represent high-stands when certain species achieved more global distribution than usual. In the late Moscovian-early Gzhelian (late Desmoinesian-early Virgilian) succession in the midcontinent United States, several major cyclothems are correlated, by both conodont species in common and cyclothem scale, with cyclothems in Russia (Moscow Basin) and Ukraine (Donets Basin), and the remaining cyclothems fit into the framework by position and scale. In this way the suggested event marker for the global Kasimovian-Gzhelian stage boundary (first appearance of Idiognathodus simulator) is supported, while possible event markers for the Moscovian-Kasimovian boundary await further evaluation.

Stratification in the lunar regolith - A preliminary view

NASA Technical Reports Server (NTRS)

Duke, M. B.; Nagle, J. S.

1975-01-01

Although our knowledge of lunar regolith stratification is incomplete, several categories of thick and thin strata have been identified. Relatively thick units average 2 to 3 cm in thickness, and appear surficially to be massive. On more detailed examination, these units can be uniformly fine-grained, can show internal trends, or can show internal variations which apparently are random. Other thick units contain soil clasts apparently reworked from underlying units. Thin laminae average approximately 1 mm in thickness; lenticular distribution and composition of some thin laminae indicates that they are fillets shed from adjacent rock fragments. Other dark fine-grained well-sorted thin laminae appear to be surficial zones reworked by micrometeorites. Interpretations of stratigraphic succession can be strengthened by the occurrence of characteristic coarse rock fragments and the orientation of large spatter agglutinates, which are commonly found in their original depositional orientation.

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

Burbank, D.W.; Whistler, D.P.

Examination of declination anomalies within a well-controlled chronologic framework can permit precise delineation of the progression of a tectonic rotation. In the past, declination anomalies from numerous spatially separated and individually dated localities have been synthesized in order to define regional, progressive rotations. Rarely, however, have magnetostratigraphic data from a single locality been used successfully to chronicle a sequential rotation that resulted from movement along a nearby fault. Magnetostratigraphic studies from the El Paso basin in southern California reveal progressively smaller amounts of counterclockwise rotation for strata dated between 11 and 7 Ma. Two tests indicate that this is amore » temporally controlled, rather than a spatially controlled, rotation. This rotation is interpreted to have resulted from sinistral shear along the Garlock fault. As such, it appears to delimit the initiation of Miocene movement along the western segment of this major strike-slip fault.« less

Revisions to the original extent of the Devonian Shale-Middle and Upper Paleozoic Total Petroleum System

USGS Publications Warehouse

Enomoto, Catherine B.; Rouse, William A.; Trippi, Michael H.; Higley, Debra K.

2016-04-11

Technically recoverable undiscovered hydrocarbon resources in continuous accumulations are present in Upper Devonian and Lower Mississippian strata in the Appalachian Basin Petroleum Province. The province includes parts of New York, Pennsylvania, Ohio, Maryland, West Virginia, Virginia, Kentucky, Tennessee, Georgia, and Alabama. The Upper Devonian and Lower Mississippian strata are part of the previously defined Devonian Shale-Middle and Upper Paleozoic Total Petroleum System (TPS) that extends from New York to Tennessee. This publication presents a revision to the extent of the Devonian Shale-Middle and Upper Paleozoic TPS. The most significant modification to the maximum extent of the Devonian Shale-Middle and Upper Paleozoic TPS is to the south and southwest, adding areas in Tennessee, Georgia, Alabama, and Mississippi where Devonian strata, including potential petroleum source rocks, are present in the subsurface up to the outcrop. The Middle to Upper Devonian Chattanooga Shale extends from southeastern Kentucky to Alabama and eastern Mississippi. Production from Devonian shale has been established in the Appalachian fold and thrust belt of northeastern Alabama. Exploratory drilling has encountered Middle to Upper Devonian strata containing organic-rich shale in west-central Alabama. The areas added to the TPS are located in the Valley and Ridge, Interior Low Plateaus, and Appalachian Plateaus physiographic provinces, including the portion of the Appalachian fold and thrust belt buried beneath Cretaceous and younger sediments that were deposited on the U.S. Gulf Coastal Plain.

[Comparative study of height and age at menarche according to the socioeconomic level in Venezuela].

PubMed

López Contreras, M; Tovar Escobar, G; Farid Coupal, N; Landaeta Jiménez, M; Méndez Castellano, H

1981-12-01

This is a retrospective study based on growth and development data published in Venezuela by various authors in the period 1936-1978. The data on height for males of the middle and high socioeconomic strata show growth curves which are very similar to the standards for British children. Likewise, the girls of the same socioeconomic condition follow the British standards, but only up to about 10-12 years of age. After that age, the girls studied by the Venezuelan authors, show a pattern of early maturation with a corresponding lower adult height compared with their British counterparts. There were differences in the growth curves according to the socioeconomic strata. These differences were more marked in the girls data. A secular increase for height was discerned, from the published data, in all socioeconomic strata and in both sexes. The data on sexual maturation showed a tendency for progressively early menarche in Venezuelan girls. These changes in growth in height and age of menarche were more notorious and came about at an earlier age in the upper socioeconomic strata. They were less marked, not constant, and came about later in the lower socioeconomic groups. The secular changes in height and sexual maturation apparent from these data, could be explained by an improvement in the environmental conditions, especially nutrition and hygiene of the population, and also be genetic heterosis from European immigration and with improvement in communications.

Vertical stratification of subsurface microbial community composition across geological formations at the Hanford Site.

PubMed

Lin, Xueju; Kennedy, David; Fredrickson, Jim; Bjornstad, Bruce; Konopka, Allan

2012-02-01

Microbial diversity in subsurface sediments at the Hanford Site 300 Area near Richland, Washington state (USA) was investigated by analysing 21 samples recovered from depths of 9-52 m. Approximately 8000 near full-length 16S rRNA gene sequences were analysed across geological strata that include a natural redox transition zone. These strata included the oxic coarse-grained Hanford formation, fine-grained oxic and anoxic Ringold Formation sediments, and the weathered basalt group. We detected 1233 and 120 unique bacterial and archaeal OTUs (operational taxonomic units at the 97% identity level) respectively. Microbial community structure and richness varied substantially across the different geological strata. Bacterial OTU richness (Chao1 estimator) was highest (> 700) in the upper Hanford formation, and declined to about 120 at the bottom of the Hanford formation. Just above the Ringold oxic-anoxic interface, richness was about 325 and declined to less than 50 in the deeper reduced zones. The deeper Ringold strata were characterized by a preponderance (c. 90%) of Proteobacteria. The bacterial community in the oxic sediments contained not only members of nine well-recognized phyla but also an unusually high proportion of three candidate divisions (GAL15, NC10 and SPAM). Additionally, 13 novel phylogenetic orders were identified within the Deltaproteobacteria, a clade rich in microbes that carry out redox transformations of metals that are important contaminants on the Hanford Site. © 2011 Society for Applied Microbiology and Blackwell Publishing Ltd.

Barriers associated with frequency of leisure-time physical activity among Brazilian adults of different income strata.

PubMed

Silva, K S; Del Duca, G F; Garcia, L M T; da Silva, J A; Bertuol, C; de Oliveira, E S A; de Barros, M V G; Nahas, M V

2016-02-01

This study aimed to estimate the prevalence of the main perceived barriers to leisure-time physical activity (LTPA) and their associations with the frequency of LTPA in a representative sample of industrial workers from Brazil (n = 47,477), according to their income strata (low income: ≤$US280, middle income: $US281-$US1400, and high income: ≥$US1401). Data were collected between 2006 and 2008 via questionnaires about the main perceived barrier to LTPA and the frequency of LTPA. Multinomial logistic regression was performed to evaluate differences among groups. There was a lower prevalence of regular practice of LTPA in the low- (15.8%) and middle-income strata (18.2%) than among the individuals of the high-income stratum (27.6%). A large proportion of workers who regularly participated in LTPA reported no barriers (low: 43.1%; middle: 46.8%; high: 51.6%). Additional obligations and fatigue were the two most common perceived barriers in all family income strata among participants who engaged in different frequencies of LTPA. The odds for all perceived barriers showed a positive trend related to frequency of LTPA (from regular to no LTPA), with higher values according to income. In summary, the ordering of the main perceived barriers to LTPA differed according to workers' income stratum and frequency of engaging in LTPA. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Sequence Stratigraphic Framework Analysis of Putaohua Oil Reservoir in Chaochang Area of Songliao Basin

NASA Astrophysics Data System (ADS)

Chang, Yan; Liu, Dameng; Yao, Yanbin

2018-01-01

The regional structure of the Changchang area in the Songliao Basin is located on the Chaoyangou terrace and Changchunling anticline belt in the central depression of the northern part of the Songliao Basin, across the two secondary tectonic units of the Chaoyanggou terrace and Changchunling anticline. However, with the continuous development of oil and gas, the unused reserves of Fuyu oil reservoir decreased year by year, and the oil field faced a serious shortage of reserve reserves. At the same time, during the evaluation process, a better oil-bearing display was found during the drilling and test oil in the Putao depression to the Chaoyanggou terraces, the Yudong-Taipingchuan area, and in the process of drilling and testing oil in the Putaohua reservoir. Zhao41, Zhao18-1, Shu38 and other exploration wells to obtain oil oil, indicating that the area has a further evaluation of the potential. Based on the principle of stratification, the Putao area was divided into three parts by using the core, logging and logging. It is concluded that the middle and western strata of the study area are well developed, including three sequences, one cycle from bottom to top (three small layers), two cycles (one small layer), three cycles (two small layers) Rhythm is positive-anti-positive. From the Midwest to the southeastern part of the strata, the strata are overtaken, the lower strata are missing, and the top rhythms become rhythmic.

Management of idiopathic intracranial hypertension with a programmable lumboperitoneal shunt: Early experience.

PubMed

Alkherayf, Fahad; Abou Al-Shaar, Hussam; Awad, Michael

2015-09-01

To evaluate the clinical outcomes and complications rate among idiopathic intracranial hypertension (IIH) patients who underwent lumboperitoneal (LP) shunt insertion with a programmable Strata valve. We retrospectively evaluated patients who underwent LP shunt with a programmable Strata valve insertion at the University of Ottawa Civic Hospital from November 2012 to June 2013. The demographic data, clinical symptoms, opening pressure, pre-operative and post-operative visual fields, neuroimaging, visual acuity, disc status, and complications were recorded and analyzed. Seven female patients with IIH underwent insertion of an LP shunt with a programmable Strata valve. The mean opening pressure was 35.8 cm H2O. The initial valve setting was 1.5, and four patients required post-operative valve pressure adjustment. All patients showed significant improvement in objective visual testing at follow-up as well as less frequent headaches. None of the patients developed intra- or post-operative complications. LP shunts with programmable Strata valve systems are a potential alternative to conventional LP and programmable ventriculoperitoneal shunt systems as well as optic nerve sheath fenestration, due to their potential in avoiding brain injury, lower failure and complication rates, lower intracranial hypotension incidence, and flexibility in adjusting valve pressure settings post-operatively evading under- and overdrainage complications. They should be considered for the management of IIH instead of early design LP systems and VP shunts. A randomized multi-center trial should be conducted to compare the efficacy of these surgical techniques. Copyright © 2015 Elsevier B.V. All rights reserved.

Thermal maturity of Jurassic shales from the Newark Basin, U.S.A.: influence of hydrothermal fluids and implications to basin modeling

USGS Publications Warehouse

Walters, C.C.; Kotra, R.K.

1990-01-01

Organic geochemical investigations were conducted on a series of cores that systematically sampled the uppermost Jurassic strata from the northern Newark Basin. Each sedimentary unit consists of fluvial red sandstones and siltstones with cyclic deposits of interbedded black lacustrine shales and gray deltaic siltstones. In a suite of organic-rich shales from the Boonton, Towaco and Feltville Formations, organic maturation parameters were used to determine aspects of the thermal history of the Newark Basin. Comparisons of model calculations and measured maturities support39 Ar/40 Ar-geochronometer studies that indicate a hydrothermal event occurred ???175 Ma ago. An increase in the regional geothermal gradient to ???7.5??C/100 m for ???5 Ma best conforms to the organic geochemical observations. Biomarker compounds in Boonton and Towaco strata should have been relatively unaltered by this regional event, but anomalous molecular distributions in the organic-rich rocks may have resulted from localized heating by hydrothermal fluids. The effects of this interaction would be very subtle and may be indistinguishable from variations caused by differences in organic facies. Within this uncertainty, sterane and hopane isomerization and steroid aromatization reactions advanced in the Boonton and Towaco Formation strata primarily because of burial and normal geothermal heating that followed the hydrothermal event. Biomarker kinetic models indicate that ???2400 m of Boonton and post-Boonton strata were eroded after basinal uplift commenced ???50 Ma ago. ?? 1990.