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Sample records for argillo-carbonated sedimentary series

  1. How much deviations in sampling sedimentary series do impact on the reconstruction of climatic cycles?

    NASA Astrophysics Data System (ADS)

    Martinez, Mathieu; Kotov, Sergey; De Vleeschouwer, David; Pas, Damien; Pälike, Heiko

    2016-04-01

    Spectral analyses have become a key tool for detecting climatic cycles (like orbital forcing) in sedimentary series. Most of spectral analyses (like Fourier Transforms and derivative, MTM…) require a constant sample step. However, this is rarely achieved when collecting rock samples in outcrops or cores. Uncertainties in the sample positions distort the sedimentary series, which reduces the power spectrum of the short periods, like precession cycles. Here, we provide a tool for assessing how much a distortion in the sampling pattern impacts on the spectral power of a sedimentary series, with special focus on the Milankovitch band. We then assess how precise should be the control of a sample position as well as the required density of samples per precession cycle for reliably assess the spectral power in the whole Milankovitch band. Sample distances are randomised using gamma models to simulate distortions of the sedimentary series. Such approach allows the stratigraphic order of samples to be maintained as well as to parameterise the mean and the variance of the dispersion of the sample distances. We tested this sample distance randomisation on two published geological datasets that have been sampled at different steps. The spectra of the non-distorted and distorted series were calculated using the Lomb-Scargle and the Multi-Taper Method. When randomising sample diatances with an uncertainty of 5% of the mean sample step, all frequencies above ~1/3 of the Nyquist frequency are significantly reduced. At 10% and 15% uncertainty, all frequencies above respectively ~1/5 and ~1/6 of the Nyquist frequency are affected. This test illustrates that a precise stratigraphic control on the sample position as well as collecting at least 6-10 samples per precession cycle are required to reliably estimate the power spectrum in the whole Milankovitch band.

  2. Testing the impact of stratigraphic uncertainty on spectral analyses of sedimentary series

    NASA Astrophysics Data System (ADS)

    Martinez, Mathieu; Kotov, Sergey; De Vleeschouwer, David; Pas, Damien; Pälike, Heiko

    2016-09-01

    Spectral analysis is a key tool for identifying periodic patterns in sedimentary sequences, including astronomically related orbital signals. While most spectral analysis methods require equally spaced samples, this condition is rarely achieved either in the field or when sampling sediment core. Here, we propose a method to assess the impact of the uncertainty or error made in the measurement of the sample stratigraphic position on the resulting power spectra. We apply a Monte Carlo procedure to randomise the sample steps of depth series using a gamma distribution. Such a distribution preserves the stratigraphic order of samples and allows controlling the average and the variance of the distribution of sample distances after randomisation. We apply the Monte Carlo procedure on two geological datasets and find that gamma distribution of sample distances completely smooths the spectrum at high frequencies and decreases the power and significance levels of the spectral peaks in an important proportion of the spectrum. At 5 % of stratigraphic uncertainty, a small portion of the spectrum is completely smoothed. Taking at least three samples per thinnest cycle of interest should allow this cycle to be still observed in the spectrum, while taking at least four samples per thinnest cycle of interest should allow its significance levels to be preserved in the spectrum. At 10 and 15 % uncertainty, these thresholds increase, and taking at least four samples per thinnest cycle of interest should allow the targeted cycles to be still observed in the spectrum. In addition, taking at least 10 samples per thinnest cycle of interest should allow their significance levels to be preserved. For robust applications of the power spectrum in further studies, we suggest providing a strong control of the measurement of the sample position. A density of 10 samples per putative precession cycle is a safe sampling density for preserving spectral power and significance level in the

  3. Time-scales of sedimentary transfer and weathering processes from U-series nuclides: Clues from the Himalayan rivers

    NASA Astrophysics Data System (ADS)

    Granet, M.; Chabaux, F.; Stille, P.; France-Lanord, C.; Pelt, E.

    2007-09-01

    In order to define time-scales of erosion and sedimentary transfer in the Himalaya, 238U- 234U- 230Th disequilibria have been analysed in river bank sediments and in bedloads collected along the Kali Gandaki river, one of the main Nepalese rivers, and in the Ghaghara and Gandak rivers, two major plain tributaries of the Ganges. The Th activity ratios and U/Th ratios in river sediments of the two Ganges tributaries constantly decrease from upstream to downstream. This is related to the maturation of sediments by weathering during their transfer to the plain. The U-series data allow to calculate a transfer time for the sediments in the alluvial Gangetic plain from the chain front to the confluence with the Ganges of about 100 kyr for both rivers. The Kali Gandaki river sediment data highlight a decrease of both the Th isotopic and U/Th ratios which is explained by a mixing between two sources with similar U/Th ratios but having suffered a different U-Th fractionation history. Interpretation of the U-series data in the frame of this scenario gives long time-scales of weathering of several 100's kyr for the Himalayan terranes. The results imply that Himalayan bedrocks are submitted to a long in situ stage of weathering before their erosion and transfer into the rivers. In addition, occurrence of similar U-Sr signatures in dissolved (i.e. < 0.1-0.2 μm) and sediment phases of the Kali Gandaki river suggests that "dissolved" uranium could be carried by colloids constituted by sedimentary microparticles. This precludes the use of U-series disequilibria in this river to calculate weathering budgets and to assess whether the erosion is working at steady-state or not.

  4. Soft-sediment deformation structures in Cambrian Series 2 tidal deposits (NW Estonia): implications for identifying endogenic triggering mechanisms in ancient sedimentary record

    NASA Astrophysics Data System (ADS)

    Põldsaar, Kairi

    2015-04-01

    Soft-sediment deformation structures (SSDS) are documented in several horizons within silt- and sandstones of the Cambrian Series 2 (Dominopolian Stage) Tiskre Formation, and some in the below-deposited argillaceous deposits of the Lükati Formation (northern part of the Baltoscandian Palaeobasin, NW Estonia). The aim of this study was to map, describe, and analyze these deformation features, discuss their deformation mechanism and possible triggers. Load structures (simple load casts, pillows, flame structures, convoluted lamination) with varying shapes and sizes occur in the Tiskre Fm in sedimentary interfaces within medium-bedded peritidal rhythmites (siltstone-argillaceous material) as well as within up to 3 m thick slightly seaward inclined stacked sandstone sequences. Homogenized beds, dish-and-pillar structures, and severely deformed bedding are also found within these stacked units and within a large tidal runoff channel infill. Autoclastic breccias and water-escape channels are rare and occur only in small-scale -- always related to thin, horizontal tidal laminae. Profound sedimentary dykes, sand volcanoes, and thrust faults, which are often related to earthquake triggered soft sediment deformation, were not observed within the studied intervals. Deformation horizon or horizons with large flat-topped pillows often with elongated morphologies occur at or near the boundary between the Tiskre and Lükati formations. Deformation mechanisms identified in this study for the various deformation types are gravitationally unstable reversed density gradient (especially in case of load features that are related to profound sedimentary interfaces) and lateral shear stress due to sediment current drag (in case of deformation structures that not related to loading at any apparent sedimentary interface). Synsedimentary liquefaction was identified as the primary driving force in most of the observed deformation horizons. Clay thixotropy may have contributed in the

  5. Sedimentary Rocks

    NASA Technical Reports Server (NTRS)

    2005-01-01

    6 November 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows outcrops of sedimentary rocks in a crater located just north of the Sinus Meridiani region. Perhaps the crater was once the site of a martian lake.

    Location near: 2.9oN, 359.0oW Image width: width: 3 km (1.9 mi) Illumination from: lower left Season: Northern Autumn

  6. Sedimentary Rocks in Ganges

    NASA Technical Reports Server (NTRS)

    2004-01-01

    13 November 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows portions of two massifs composed of light-toned, sedimentary rock in Ganges Chasma, part of the Valles Marineris trough system. On the steeper slopes in this vista, dry talus shed from the outcrop has formed a series of dark fans. Surrounded by dark, windblown sand, these landforms are located near 8.6oS, 46.8oW. The image covers an area approximately 3 km (1.9 mi) across and sunlight illuminates the scene from the upper left.

  7. The Martian sedimentary record

    NASA Technical Reports Server (NTRS)

    Dehon, R. A.

    1987-01-01

    The differences between the surface geology of Mars and earth are discussed. Sedimentary processes and fluvial systems on Mars are examined. Surface mapping reveals the more recent depostional patterns. In future missions, radar sounding, active seismic systems, and on site deep drilling may be required to fully document the depositional history. For the present, identification of sedimentary layers must rest on localities of tectonic or erosional windows, detection of buried surfaces by indirect methods, and deposition or off lap patterns of distribution.

  8. Inversion of Extensional Sedimentary Basins

    NASA Astrophysics Data System (ADS)

    Buiter, Susanne J. H.; Pfiffner, O. Adrian

    The evolution of extensional sedimentary basins is governed by the surrounding stress field and can, therefore, be expected to be highly sensitive to variations in these stresses. Important changes in basin geometry are to be expected in the case of an even short-lived reversal from extension to compression. We investigate the evolu- tion of fold and thrust structures which form in compression after extension, when basin forming processes have come to a complete stop. To this purpose, we use a two- dimensional, viscoplastic model and start our experiments from a pre-existing exten- sional geometry. We illustrate the sensitivity of the evolving structures to inherited extensional geometry, sedimentary and erosional processes, and material properties. One series of our model experiments involves the upper- to middle crust only in order to achieve a high detail in the basin area. We find that our results agree with examples from nature and analogue studies in, among others, the uplift and rotation of syn-rift sediments, the propagation of shear zones into the post-rift sediments and, in specific cases, the development of back-thrusts or basement short-cut faults. We test the out- come of these models by performing a second series of model simulations in which basins on a continental margin are inverted through their progressive approach of a subduction zone. These latter models are on the scale of the whole upper mantle.

  9. Gale Sedimentary Rocks

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-439, 1 August 2003

    Gale Crater, located in the Aeolis region near 5.5oS, 222oW, contains a mound of layered sedimentary rock that stands higher than the rim of the crater. This giant mound suggests that the entire crater was not only once filled with sediment, it was also buried beneath sediment. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows some of the eroded remains of the sedimentary rock that once filled Gale Crater. The layers form terraces; wind has eroded the material to form the tapered, pointed yardang ridges seen here. The small circular feature in the lower right quarter of the picture is a mesa that was once a small meteor impact crater that was filled, buried, then exhumed from within the sedimentary rock layers exposed here. This image is illuminated from the left.

  10. Sedimentary Rocks and Dunes

    NASA Technical Reports Server (NTRS)

    2004-01-01

    25 November 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows buttes composed of light-toned, sedimentary rock exposed by erosion within a crater occurring immediately west of Schiaparelli Basin near 4.0oS, 347.9oW. Surrounding these buttes is a field of dark sand dunes and lighter-toned, very large windblown ripples. The sedimentary rocks might indicate that the crater interior was once the site of a lake. The image covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.

  11. Sedimentary Rock Remnants

    NASA Technical Reports Server (NTRS)

    2005-01-01

    29 July 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows knobs of remnant, wind-eroded, layered sedimentary rock that once completely covered the floor of a crater located west of the Sinus Meridiani region of Mars. Sedimentary rock outcrops are common throughout the Sinus Meridiani region and its surrounding cratered terrain.

    Location near: 2.2oN, 7.9oW Image width: width: 3 km (1.9 mi) Illumination from: lower left Season: Northern Autumn

  12. Gale Sedimentary Rocks

    NASA Technical Reports Server (NTRS)

    2005-01-01

    15 April 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows outcroppings of layered, sedimentary rock in eastern Gale Crater. North-central Gale Crater is the site of a mound that is more than several kilometers thick and largely composed of sedimentary rocks that record a complex history of deposition and erosion. At one time, Gale Crater might have been completely filled and buried beneath the martian surface.

    Location near: 4.9oS, 221.6oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Winter

  13. Sedimentary Rock Layers

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-348, 2 May 2003

    This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image acquired in March 2003 shows dozens of repeated layers of sedimentary rock in a western Arabia Terra crater at 8oN, 7oW. Wind has sculpted the layered forms into hills somewhat elongated toward the lower left (southwest). The dark patches at the bottom (south) end of the image are drifts of windblown sand. These sedimentary rocks might indicate that the crater was once the site of a lake--or they may result from deposition by wind in a completely dry, desert environment. Either way, these rocks have something important to say about the geologic history of Mars. The area shown is about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the left.

  14. Schiaparelli's Sedimentary Rocks

    NASA Technical Reports Server (NTRS)

    2004-01-01

    9 October 2004 Schiaparelli Basin is a large, 470 kilometer (292 miles) impact crater located east of Sinus Meridiani. The basin might once have been the site of a large lake--that is, if the sedimentary rocks exposed on its northwestern floor were deposited in water. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a 1.5 meter per pixel (5 ft per pixel) view of some of the light-toned, finely-bedded sedimentary rocks in northwestern Schiaparelli. The image is located near 1.0oS, 346.0oW, and covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the left.

  15. Tithonium Chasma's Sedimentary Rocks

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-565, 5 December 2003

    Exposures of light-toned, layered, sedimentary rocks are common in the deep troughs of the Valles Marineris system. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example from western Tithonium Chasma. The banding seen here is an eroded expression of layered rock. Sedimentary rocks can be composed of (1) the detritus of older, eroded and weathered rocks, (2) grains produced by explosive volcanism (tephra, also known as volcanic ash), or (3) minerals that were chemically precipitated out of a body of liquid such as water. These outcrops are located near 4.8oS, 89.7oW. The image covers an area 3 km (1.9 mi) wide and is illuminated from the lower left.

  16. Broken Sedimentary Rocks

    NASA Technical Reports Server (NTRS)

    2005-01-01

    18 May 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows broken-up blocks of sedimentary rock in western Candor Chasma. There are several locations in western Candor that exhibit this pattern of broken rock. The manner in which these landforms were created is unknown; it is possible that there was a landslide or a meteoritic impact that broke up the materials. One attribute that is known: in some of these cases, it seems that the rock was broken and then buried by later sedimentary rocks, before later being exhumed so that they can be seen from orbit today.

    Location near: 6.9oS, 75.5oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Winter

  17. Ancient Sedimentary Rocks

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-469, 31 August 2003

    The terraced area in this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image is an outcropping of ancient, sedimentary rock. It occurs in a crater in western Arabia Terra near 10.8oN, 4.5oW. Sedimentary rocks provide a record of past environments on Mars. Field work will likely be required to begin to get a good understanding of the nature of the record these rocks contain. Their generally uniform thickness and repeated character suggests that deposition of fine sediment in this crater was episodic, if not cyclic. These rocks might be indicators of an ancient lake, or they might have been deposited from grains settling out of an earlier, thicker, martian atmosphere. This image covers an area 3 km (1.9 mi) across and is illuminated from the lower left.

  18. Terby Sedimentary Rocks

    NASA Technical Reports Server (NTRS)

    2004-01-01

    27 December 2003 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows layered sedimentary rock outcrops in Terby Crater, located near 27.7oS, 285.4oW. The layered sediments in Terby are several kilometers thick, attesting to a long history of deposition in this ancient basin. The picture covers an area 3 km (1.9 mi) wide. Sunlight illuminates the scene from the upper left.

  19. Iani Sedimentary Rocks

    NASA Technical Reports Server (NTRS)

    2005-01-01

    23 February 2005 This Mars Global Surveyor (MGS) Orbiter Camera (MOC) image shows light-toned sedimentary rocks exposed by erosion in the Iani Chaos region of Mars.

    Location near: 4.2oS, 18.7oW Image width: 1 km (0.6 mi) Illumination from: upper left Season: Southern Winter

  20. Melas Sedimentary Rocks

    NASA Technical Reports Server (NTRS)

    2004-01-01

    17 July 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows layered, sedimentary rock outcrops in southwestern Melas Chasma, one of the troughs of the vast Valles Marineris system. Sunlight illuminates this scene from the upper left; it is located near 9.8oS, 76.0oW, and covers an area about 3 km (1.9 mi) wide.

  1. Eroded Sedimentary Rock

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-372, 26 May 2003

    This high resolution Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows eroded, layered sedimentary rock exposures in an unnamed western Arabia Terra crater at 8oN, 7oW. The dark material is windblown sand; much of the erosion of these layers may have also been caused by wind. Sunlight illuminates the scene from the left.

  2. Evolution of Sedimentary Rocks

    NASA Astrophysics Data System (ADS)

    Veizer, J.; MacKenzie, F. T.

    2003-12-01

    For almost a century, it has been recognized that the present-day thickness and areal extent of Phanerozoic sedimentary strata increase progressively with decreasing geologic age. This pattern has been interpreted either as reflecting an increase in the rate of sedimentation toward the present (Barrell, 1917; Schuchert, 1931; Ronov, 1976) or as resulting from better preservation of the younger part of the geologic record ( Gilluly, 1949; Gregor, 1968; Garrels and Mackenzie, 1971a; Veizer and Jansen, 1979, 1985).Study of the rocks themselves led to similarly opposing conclusions. The observed secular (=age) variations in relative proportions of lithological types and in chemistry of sedimentary rocks (Daly, 1909; Vinogradov et al., 1952; Nanz, 1953; Engel, 1963; Strakhov, 1964, 1969; Ronov, 1964, 1982) were mostly given an evolutionary interpretation. An opposing, uniformitarian, approach was proposed by Garrels and Mackenzie (1971a). For most isotopes, the consensus favors deviations from the present-day steady state as the likely cause of secular trends.This chapter attempts to show that recycling and evolution are not opposing, but complementary, concepts. It will concentrate on the lithological and chemical attributes of sediments, but not deal with the evolution of sedimentary mineral deposits (Veizer et al., 1989) and of life ( Sepkoski, 1989), both well amenable to the outlined conceptual treatment. The chapter relies heavily on Veizer (1988a) for the sections dealing with general recycling concepts, on Veizer (2003) for the discussion of isotopic evolution of seawater, and on Morse and Mackenzie (1990) and Mackenzie and Morse (1992) for discussion of carbonate rock recycling and environmental attributes.

  3. Melas Sedimentary Rocks

    NASA Technical Reports Server (NTRS)

    2004-01-01

    28 August 2004 Light-toned, layered, sedimentary rock outcrops are common within the vast martian Valles Marineris trough system. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a recent example from southern Melas Chasma at 1.5 m/pixel (5 ft/pixel) resolution. The image is located near 11.3oS, 73.9oW, and covers an area about 1.8 km (1.1 mi) across. Sunlight illuminates the scene from the upper left.

  4. Sedimentary Rocks in Melas

    NASA Technical Reports Server (NTRS)

    2005-01-01

    This Mars Global Surveyor (MGS) Orbiter Camera (MOC) image shows a butte and several other landforms eroded into light-toned, layered, sedimentary rock in southern Melas Chasma. Melas is part of the vast Valles Marineris trough system.

    Location near: 11.8oS, 74.6oW Image width: 3.0 km (1.9 mi) Illumination from: lower left Season: Southern Spring

  5. Sedimentary Rock in Candor

    NASA Technical Reports Server (NTRS)

    2005-01-01

    11 February 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows dozens of light- and a few dark-toned sedimentary rock layers exposed by faulting and erosion in western Candor Chasma, part of the vast Valles Marineris trough system.

    Location near: 6.5oS, 77.0oW Image width: 3.0 km (1.9 mi) Illumination from: upper left Season: Southern Autumn

  6. Sedimentary Rock Layers

    NASA Technical Reports Server (NTRS)

    2004-01-01

    27 January 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows layers of sedimentary rock in a crater in western Arabia Terra. Layered rock records the history of a place, but an orbiter image alone cannot tell the entire story. These materials record some past episodes of deposition of fine-grained material in an impact crater that is much larger than the image shown here. The picture is located near 3.4oN, 358.7oW, and covers an area 3 km (1.9 mi.) wide. Sunlight illuminates the scene from the lower left.

  7. Schiaparelli Sedimentary Rocks

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-403, 26 June 2003

    Some of the most important high resolution imaging results of the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) experiment center on discoveries about the presence and nature of the sedimentary rock record on Mars. This old meteor impact crater in northwestern Schiaparelli Basin exhibits a spectacular view of layered, sedimentary rock. The 2.3 kilometer (1.4 miles) wide crater may have once been completely filled with sediment; the material was later eroded to its present form. Dozens of layers of similar thickness and physical properties are now expressed in a wedding cake-like stack in the middle of the crater. Sunlight illuminating the scene from the left shows that the circle, or mesa top, at the middle of the crater stands higher than the other stair-stepped layers. The uniform physical properties and bedding of these layers might indicate that they were originally deposited in a lake (it is possible that the crater was at the bottom of a much larger lake, filling Schiaparelli Basin); alternatively, the layers were deposited by settling out of the atmosphere in a dry environment. This picture was acquired on June 3, 2003, and is located near 0.9oS, 346.2oW.

  8. South American sedimentary basins

    SciTech Connect

    Urien, C.M.

    1984-04-01

    More than 64 sedimentary basins have been identified on the South American continent. According to their regional structural character and tectonic setting, they are classified in 4 super groups. About 20 interior or intracratonic basins occur on South American cratons (Guayanas, Brazilian, and Patagonian). In most cases, their sedimentary fill is Paleozoic or early Mesozoic. Rift or transverse grabens resulting from incipient sea floor spreading extend towards the continental margin. Seventeen basins are located along the Atlantic stable margin, and consist primarily of half grabens with downfaulted seaward blocks. These rifts (or pull-apart basins) were separated as results of the migration of the African and American continental blocks. Therefore the sedimentation is chiefly Cretaceous and Tertiary. On the western edge of South American cratons, almost 20 basins of downwarped blocks extend from Orinoco down to the Malvinas plateau in a relatively uninterrupted chain of retroarc basins, bordered by the Andean orogen. They lie on a flexured Precambrian and Paleozoic basement, and are highly deformed in the west (Subandean belt) due to the action of compressional forces caused by the tectonic influence of the Mesozoic Andean batholith. Westward, the Pacific margin is bordered by 27 foreland and forearc basins, which alternate from north to south on an unstable or quasistable margin, fringed by a trench and slope complex where the ocean crust is subducted beneath the continental plate.

  9. Faulted Sedimentary Rocks

    NASA Technical Reports Server (NTRS)

    2004-01-01

    27 June 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows some of the layered, sedimentary rock outcrops that occur in a crater located at 8oN, 7oW, in western Arabia Terra. Dark layers and dark sand have enhanced the contrast of this scene. In the upper half of the image, one can see numerous lines that off-set the layers. These lines are faults along which the rocks have broken and moved. The regularity of layer thickness and erosional expression are taken as evidence that the crater in which these rocks occur might once have been a lake. The image covers an area about 1.9 km (1.2 mi) wide. Sunlight illuminates the scene from the lower left.

  10. Meridiani Sedimentary Rocks

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-545, 15 November 2003

    Northern Sinus Meridiani is a region of vast exposures of layered, sedimentary rock. Buried within these layers are many filled impact craters. Erosion has re-exposed several formerly-buried craters in this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image. Arrows 1 and 2 indicate craters that are still emerging from beneath layered material; arrow 3 indicates a crater that has been fully re-exposed. This image is located near 5.1oN, 2.7oW. The area shown is about 3 km (1.9 mi) wide and illuminated from the left/upper left.

  11. Ladon Sedimentary Rocks

    NASA Technical Reports Server (NTRS)

    2005-01-01

    6 June 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows light-toned, layered, sedimentary rocks exposed by the fluids that carved the Ladon Valles system in the Erythraeum region of Mars. These rocks are so ancient that their sediments were deposited, cemented to form rock, and then eroded by the water (or other liquid) that carved Ladon Valles, so far back in Martian history that such liquids could still flow on the planet's surface.

    Location near: 20.8oS, 30.0oW Image width: 3 km (1.9 mi Illumination from: upper left Season: Southern Spring

  12. Sedimentary Rock Outcrops

    NASA Technical Reports Server (NTRS)

    2004-01-01

    16 August 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows eroded layered rock outcrops in a crater north of Meridiani Planum near 2.7oN, 359.1oW. The dozens and dozens of sedimentary rock layers of repeated thickness and similar physical properties at this location suggest that they may have been deposited in a lacustrine (lake) setting. The crater in which these layers occur may once have been completely filled and buried, as is the case for many craters in the Sinus Meridiani region. This image covers an area about 3 km (1.9 mi) across; sunlight illuminates the scene from the left.

  13. Sedimentary Rock Near Coprates

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-420, 13 July 2003

    This mosaic of two Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) narrow angle camera images, one from 2001, the other from 2003, shows light-toned, layered, sedimentary rock outcrops exposed on the floor of a trough that parallels Coprates Chasma in the Valles Marineris system. Layered rocks form the pages from which the history of a place can be read. It may be many years before the story is read, but or now at least we know where one of the books of martian history is found. This picture is located near 15.2oS, 60.1oW. Sunlight illuminates the scene from the left.

  14. Sedimentary condensation and authigenesis

    NASA Astrophysics Data System (ADS)

    Föllmi, Karl

    2016-04-01

    Most marine authigenic minerals form in sediments, which are subjected to condensation. Condensation processes lead to the formation of well individualized, extremely thin (< 1m) beds, which were accumulated during extremely long time periods (> 100ky), and which experienced authigenesis and the precipitation of glaucony, verdine, phosphate, iron and manganese oxyhydroxides, iron sulfide, carbonate and/or silica. They usually show complex internal stratigraphies, which result from an interplay of sediment accumulation, halts in sedimentation, sediment winnowing, erosion, reworking and bypass. They may include amalgamated faunas of different origin and age. Hardgrounds may be part of condensed beds and may embody strongly condensed beds by themselves. Sedimentary condensation is the result of a hydrodynamically active depositional regime, in which sediment accumulation, winnowing, erosion, reworking and bypass are processes, which alternate as a function of changes in the location and intensity of currents, and/or as the result of episodic high-energy events engendered by storms and gravity flow. Sedimentary condensation has been and still is a widespread phenomenon in past and present-day oceans. The present-day distribution of glaucony and verdine-rich sediments on shelves and upper slopes, phosphate-rich sediments and phosphorite on outer shelves and upper slopes, ferromanganese crusts on slopes, seamounts and submarine plateaus, and ferromanganese nodules on abyssal seafloors is a good indication of the importance of condensation processes today. In the past, we may add the occurrence of oolitic ironstone, carbonate hardgrounds, and eventually also silica layers in banded iron formations as indicators of the importance of condensation processes. Besides their economic value, condensed sediments are useful both as a carrier of geochemical proxies of paleoceanographic and paleoenvironmental change, as well as the product of episodes of paleoceanographic and

  15. Ganges Sedimentary Rocks

    NASA Technical Reports Server (NTRS)

    2004-01-01

    24 May 2004 Mariner 9 images acquired in 1972 first revealed a large, light-toned, layered mound in Ganges Chasma, part of the vast Valles Marineris trough system. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a higher-resolution view of these rocks than was achieved by Mariner 9 or Viking, and higher than can be obtained by Mars Odyssey or Mars Express. The image, with a resolution of about 3.7 meters (12 feet) per pixel, shows eroded layered rock outcrops in Ganges Chasma. These rocks record a history of events that occurred either in Ganges Chasma, or in the rocks brought to the surface by the opening of Ganges Chasma. Either way, the story they might tell could be as fascinating and unprecedented as the story told by sedimentary rocks investigated this year in Meridiani Planum by the Opportunity Mars Exploration Rover ... no one knows. The image is located near 7.3oS, 48.8oW, and covers an area about 3 km (1.9 mi) across. The picture is illuminated by sunlight from the upper left.

  16. Martian sediments and sedimentary rocks

    NASA Technical Reports Server (NTRS)

    Markun, C. D.

    1988-01-01

    Martian sediments and sedimentary rocks, clastic and nonclastic, should represent a high priority target in any future return-sample mission. The discovery of such materials and their subsequent analysis in terrestrial laboratories, would greatly increase the understanding of the Martian paleoclimate. The formation of Martian clastic sedimentary rocks, under either present, low-pressure, xeric conditions or a postulated, high-pressure, hydric environment, depends upon the existence of a supply of particles, various cementing agents and depositional basins. A very high resolution (mm-cm range) photographic reconnaissance of these areas would produce a quantum jump in the understanding of Martian geological history. Sampling would be confined to more horizontal (recent) surfaces. Exploration techniques are suggested for various hypothetical Martian sedimentary rocks.

  17. Sedimentary petrology. 2nd edition

    SciTech Connect

    Blatt, H.

    1992-01-01

    The second edition of Sedimentary Petrology is extensively revised and updated; much effort has been expended to strengthen the weaknesses of the earlier edition, and much of this effort has been successful. It consists of sixteen chapters. Following two introductory chapters (occurrence of sedimentary rocks; weathering and soils), eleven chapters cover the various sedimentary rock types. Coverage is allocated in proportion to their relative abundance and relative ease of study -- three chapters on conglomerates and sandstones (textures and structures, composition, and diagenesis); one on mud rocks; three on carbonates (limestone textures, structures, and environments; limestone mineralogy and diagenesis; and dolostones); and one each on evaporites, cherts, iron-rich rocks, and phosphorites. A novel and useful chapter on paleogeothermometry rounds out the discussion of rocks, followed by chapters on The Development of a Research Project'' and common laboratory methods.

  18. Sedimentary Rocks of Aram Chaos

    NASA Technical Reports Server (NTRS)

    2004-01-01

    4 February 2004 Aram Chaos is a large meteor impact crater that was nearly filled with sediment. Over time, this sediment was hardened to form sedimentary rock. Today, much of the eastern half of the crater has exposures of light-toned sedimentary rock, such as the outcrops shown in this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image. The picture is located near 2.0oN, 20.3oW, and covers an area 3 km (1.9 mi) wide. Sunlight illuminates the scene from the left.

  19. Geochemistry of sedimentary ore deposits

    SciTech Connect

    Maynard, J. B.

    1983-01-01

    A text providing a sedimentological treatment of a study on ore deposits, and especially as related to geochemistry. Excellently documented (about 5000 citations). Well indexed with the index of deposits and localities separated. Contents, Iron. Copper and silver. Aluminum and nickel. Manganese. Uranium. Lead and zinc. Volcanic-sedimentary ores. Appendix. Indexes.

  20. Quantitative characterisation of sedimentary grains

    NASA Astrophysics Data System (ADS)

    Tunwal, Mohit; Mulchrone, Kieran F.; Meere, Patrick A.

    2016-04-01

    Analysis of sedimentary texture helps in determining the formation, transportation and deposition processes of sedimentary rocks. Grain size analysis is traditionally quantitative, whereas grain shape analysis is largely qualitative. A semi-automated approach to quantitatively analyse shape and size of sand sized sedimentary grains is presented. Grain boundaries are manually traced from thin section microphotographs in the case of lithified samples and are automatically identified in the case of loose sediments. Shape and size paramters can then be estimated using a software package written on the Mathematica platform. While automated methodology already exists for loose sediment analysis, the available techniques for the case of lithified samples are limited to cases of high definition thin section microphotographs showing clear contrast between framework grains and matrix. Along with the size of grain, shape parameters such as roundness, angularity, circularity, irregularity and fractal dimension are measured. A new grain shape parameter developed using Fourier descriptors has also been developed. To test this new approach theoretical examples were analysed and produce high quality results supporting the accuracy of the algorithm. Furthermore sandstone samples from known aeolian and fluvial environments from the Dingle Basin, County Kerry, Ireland were collected and analysed. Modern loose sediments from glacial till from County Cork, Ireland and aeolian sediments from Rajasthan, India have also been collected and analysed. A graphical summary of the data is presented and allows for quantitative distinction between samples extracted from different sedimentary environments.

  1. Polygon/Cracked Sedimentary Rock

    NASA Technical Reports Server (NTRS)

    2004-01-01

    4 December 2004 Exposures of sedimentary rock are quite common on the surface of Mars. Less common, but found in many craters in the regions north and northwest of the giant basin, Hellas, are sedimentary rocks with distinct polygonal cracks in them. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example from the floor of an unnamed crater near 21.0oS, 311.9oW. Such cracks might have formed by desiccation as an ancient lake dried up, or they might be related to ground ice freeze/thaw cycles or some other stresses placed on the original sediment or the rock after it became lithified. The 300 meter scale bar is about 328 yards long. The scene is illuminated by sunlight from the upper left.

  2. Sedimentary Rocks of Aram Chaos

    NASA Technical Reports Server (NTRS)

    2004-01-01

    10 May 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows outcroppings of light-toned, layered, sedimentary rock within Aram Chaos, an ancient, partly-filled impact crater located near 3.2oN, 19.9oW. This 1.5 meters (5 feet) per pixel picture is illuminated by sunlight from the left and covers an area about 3 km (1.9 mi) across.

  3. Permanganate diffusion and reaction in sedimentary rocks.

    PubMed

    Huang, Qiuyuan; Dong, Hailiang; Towne, Rachael M; Fischer, Timothy B; Schaefer, Charles E

    2014-04-01

    In situ chemical oxidation using permanganate has frequently been used to treat chlorinated solvents in fractured bedrock aquifers. However, in systems where matrix back-diffusion is an important process, the ability of the oxidant to migrate and treat target contaminants within the rock matrix will likely determine the overall effectiveness of this remedial approach. In this study, a series of diffusion experiments were performed to measure the permanganate diffusion and reaction in four different types of sedimentary rocks (dark gray mudstone, light gray mudstone, red sandstone, and tan sandstone). Results showed that, within the experimental time frame (~2 months), oxidant migration into the rock was limited to distances less than 500 μm. The observed diffusivities for permanganate into the rock matrices ranged from 5.3 × 10(-13) to 1.3 × 10(-11) cm(2)/s. These values were reasonably predicted by accounting for both the rock oxidant demand and the effective diffusivity of the rock. Various Mn minerals formed as surface coatings from reduction of permanganate coupled with oxidation of total organic carbon (TOC), and the nature of the formed Mn minerals was dependent upon the rock type. Post-treatment tracer testing showed that these Mn mineral coatings had a negligible impact on diffusion through the rock. Overall, our results showed that the extent of permanganate diffusion and reaction depended on rock properties, including porosity, mineralogy, and organic carbon. These results have important implications for our understanding of long-term organic contaminant remediation in sedimentary rocks using permanganate.

  4. Sedimentary Rocks in Ladon Vallis

    NASA Technical Reports Server (NTRS)

    2004-01-01

    25 January 2004 This is a Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture of an outcrop of light-toned, layered, sedimentary rock exposed by erosion in Ladon Vallis. These rocks preserve clues to the martian past. However, like books in a library, one needs to go there and check them out if one wishes to read what the layers have to say. This November 2003 picture is located near 21.1oS, 29.8oW, and covers an area 3km (1.9 mi.) wide. Sunlight illuminates the scene from the left.

  5. Sedimentary rocks of early Mars.

    PubMed

    Malin, M C; Edgett, K S

    2000-12-08

    Layered and massive outcrops on Mars, some as thick as 4 kilometers, display the geomorphic attributes and stratigraphic relations of sedimentary rock. Repeated beds in some locations imply a dynamic depositional environment during early martian history. Subaerial (such as eolian, impact, and volcaniclastic) and subaqueous processes may have contributed to the formation of the layers. Affinity for impact craters suggests dominance of lacustrine deposition; alternatively, the materials were deposited in a dry, subaerial setting in which atmospheric density, and variations thereof mimic a subaqueous depositional environment. The source regions and transport paths for the materials are not preserved.

  6. Multisensor classification of sedimentary rocks

    NASA Technical Reports Server (NTRS)

    Evans, Diane

    1988-01-01

    A comparison is made between linear discriminant analysis and supervised classification results based on signatures from the Landsat TM, the Thermal Infrared Multispectral Scanner (TIMS), and airborne SAR, alone and combined into extended spectral signatures for seven sedimentary rock units exposed on the margin of the Wind River Basin, Wyoming. Results from a linear discriminant analysis showed that training-area classification accuracies based on the multisensor data were improved an average of 15 percent over TM alone, 24 percent over TIMS alone, and 46 percent over SAR alone, with similar improvement resulting when supervised multisensor classification maps were compared to supervised, individual sensor classification maps. When training area signatures were used to map spectrally similar materials in an adjacent area, the average classification accuracy improved 19 percent using the multisensor data over TM alone, 2 percent over TIMS alone, and 11 percent over SAR alone. It is concluded that certain sedimentary lithologies may be accurately mapped using a single sensor, but classification of a variety of rock types can be improved using multisensor data sets that are sensitive to different characteristics such as mineralogy and surface roughness.

  7. Sedimentary record of erg migration

    SciTech Connect

    Porter, M.L.

    1986-06-01

    The sedimentary record of erg (eolian sand sea) migration consists of an idealized threefold division of sand-sea facies sequences. The basal division, here termed the fore-erg, is composed of a hierarchy of eolian sand bodies contained within sediments of the flanking depositional environment. The fore-erg represents the downwind, leading edge of the erg and records the onset of eolian sedimentation. Basin subsidence coupled with erg migration places the medial division, termed the central erg, over the fore-erg strata. Eolian influence on regional sedimentation patterns is greatest in the central erg, and most of the sand transported and deposited in the erg is contained within this region. Reduction in sand supply and continued erg migration will cover the central-erg deposits with a veneer of back-erg deposits. This upper division of the erg facies sequence resembles closely the fore-erg region. Back-erg deposits may be thin due to limited eolian influence on sedimentation or incomplete erg migration, or they may be completely absent because of great susceptibility to postdepositional erosion. Tectonic, climatic, and eustatic influences on sand-sea deposition will produce distinctive variations or modifications of the idealized erg facies sequence. The resulting variants in the sedimentary record of erg migration are illustrated with ancient examples from western North America, Europe, southern Africa, and South America. 38 references, 2 figures, 2 tables.

  8. Geodynamic evolution of early Mesozoic sedimentary basins in eastern Australia

    NASA Astrophysics Data System (ADS)

    Rosenbaum, G.; Babaahmadi, A.; Esterle, J.

    2014-12-01

    Eastern Australia is covered by a series of continental sedimentary basins deposited during the Triassic and Jurassic, but the geodynamic context of these basins is not fully understood. Using gridded aeromagnetic data, seismic reflection data, geological maps, digital elevation models, and field observations, we conducted a structural synthesis aimed at characterizing major structures and deformation style in the Triassic-Jurassic sedimentary basins of eastern Australia. Our results show evidence for four alternating episodes of rifting and contractional events during the Triassic. Two major episodes of rifting, characterized by syn-sedimentary steep normal faults and bimodal volcanism, resulted in the development of the Early-Middle Triassic Esk-Nymboida Rift System and the early Late Triassic Ipswich Basin. Faults in the Esk-Nymboida Rift System have been controlled by a pre-existing oroclinal structure. Each phase of rifting was followed by a contractional event, which produced folds, reverse faults and unconformities in the basins. Since the latest Late Triassic, thermal subsidence led to the deposition of continental sediments in the Clarence-Moreton Basin, which continued until the Early Cretaceous. We suggest that the geodynamic control on the alternating episodes of rifting and contraction during the Triassic in eastern Australia was ultimately related to plate boundary migration and switches between trench retreat and advance.

  9. Elastic Properties of Sedimentary Rocks

    NASA Astrophysics Data System (ADS)

    Melendez Martinez, Jaime

    Sedimentary rocks are an important research topic since such rocks are associated to sources of ground water as well as oil, gas, and mineral reservoirs. In this work, elastic and physical properties of a variety of sedimentary samples that include glacial sediments, carbonates, shales, one evaporite, and one argillite from a variety of locations are investigated. Assuming vertical transverse isotropy, ultrasonic compressional- and shear-waves (at 1 MHz central frequency) were measured as a function of confining pressure on all samples with the exception of glacial samples which were tested assuming isotropy. Tensile strength tests (Brazilian test) were also carried out on selected glacial samples and, in addition, static-train measurements were conducted on shales and argillite samples. Lithological and textural features of samples were obtained through thin section techniques, scanning electron microscopy images and micro-tomography images. X-ray diffraction and X-Ray fluorescence provided the mineralogical oxides content information. Porosity, density, and pore structure were studied by using a mercury intrusion porosimeter and a helium pycnometer. The wide range of porosities of the studied samples (ranging from a minimum of 1% for shales to a maximum 45% for some glacial sediments) influence the measured velocities since high porosity sample shows an noticeable velocity increment as confining pressure increases as a consequence of closure of microcracks and pores, unlike low porosity samples where increment is quasi-lineal. Implementation of Gassmann's relation to ultrasonic velocities obtained from glacial samples has negligible impact on them when assuming water saturated samples, which suggests that state of saturation it is no so important in defining such velocities and instead they are mainly frame-controlled. On the other hand, velocities measured on carbonate and evaporite samples show that samples are at best weak anisotropic, thus the intrinsic

  10. The White Nile sedimentary system

    NASA Astrophysics Data System (ADS)

    Garzanti, Eduardo; Andò, Sergio; Padoan, Marta; Resentini, Alberto; Vezzoli, Giovanni; Villa, Igor

    2014-05-01

    The Nile River flows for ~6700 km from south of the Equator to finally reach the Mediterranean Sea at northern subtropical latitudes (Woodward et al. 2007). This is the longest sedimentological laboratory on Earth, a unique setting in which we are investigating changes in sediment composition associated with diverse chemical and physical processes, including weathering and hydraulic sorting. The present study focuses on the southern branch of the Nile across 20° of latitude, from hyperhumid Burundi and Rwanda highlands in central Africa to Khartoum, the capital city of Sudan at the southern edge of the Sahara. Our study of the Kagera basin emphasizes the importance of weathering in soils at the source rather than during stepwise transport, and shows that the transformation of parent rocks into quartzose sand may be completed in one sedimentary cycle (Garzanti et al. 2013a). Micas and heavy minerals, less effectively diluted by recycling than main framework components, offer the best key to identify the original source-rock imprint. The different behaviour of chemical indices such as the CIA (a truer indicator of weathering) and the WIP (markedly affected by quartz dilution) helps us to distinguish strongly weathered first-cycle versus polycyclic quartz sands (Garzanti et al. 2013b). Because sediment is efficiently trapped in East African Rift lakes, the composition of Nile sediments changes repeatedly northwards across Uganda. Downstream of both Lake Kyoga and Lake Albert, quartzose sands are progressively enriched in metamorphiclastic detritus supplied from tributaries draining amphibolite-facies basements. The evolution of White Nile sediments across South Sudan, a scarcely accessible region that suffered decades of civil war, was inferred from the available information (Shukri 1950), integrated by original petrographic, heavy-mineral and geochemical data (Padoan et al. 2011). Mineralogical and isotopic signatures of Bahr-el-Jebel and Sobat sediments, derived

  11. Diffusive flux and pore anisotropy in sedimentary rocks.

    PubMed

    Schaefer, C E; Towne, R M; Lazouskaya, V; Bishop, M E; Dong, H

    2012-04-01

    Diffusion of dissolved contaminants into or from bedrock matrices can have a substantial impact on both the extent and longevity of dissolved contaminant plumes. For layered rocks, bedding orientation can have a significant impact on diffusion. A series of laboratory experiments was performed on minimally disturbed bedrock cores to measure the diffusive flux both parallel and normal to mineral bedding of four different anisotropic sedimentary rocks. Measured effective diffusion coefficients ranged from 4.9×10(-8) to 6.5×10(-7)cm(2)/s. Effective diffusion coefficients differed by as great as 10-folds when comparing diffusion normal versus parallel to bedding. Differences in the effective diffusion coefficients corresponded to differences in the "apparent" porosity in the orientation of diffusion (determined by determining the fraction of pore cross-sectional area measured using scanning electron microscopy), with the difference in apparent porosity between normal and parallel bedding orientations differing by greater than 2-folds for two of the rocks studied. Existing empirical models failed to provide accurate predictions of the effective diffusion coefficient in either bedding orientation for all four rock types studied, indicating that substantial uncertainty exists when attempting to predict diffusive flux through sedimentary rocks containing mineral bedding. A modified model based on the apparent porosity of the rocks provided a reasonable prediction of the experimental diffusion data.

  12. Sedimentary Rocks and Methane - Southwest Arabia Terra

    NASA Technical Reports Server (NTRS)

    Allen, Carlton C.; Oehler, Dorothy Z.; Venechuk, Elizabeth M.

    2006-01-01

    We propose to land the Mars Science Laboratory in southwest Arabia Terra to study two key aspects of martian history the extensive record of sedimentary rocks and the continuing release of methane. The results of this exploration will directly address the MSL Scientific Objectives regarding biological potential, geology and geochemistry, and past habitability.

  13. Layer formation in sedimentary fingering convection

    NASA Astrophysics Data System (ADS)

    Reali, J. F.; Garaud, P.; Alsinan, A.; Meiburg, E.

    2017-04-01

    When particles settle through a stable temperature or salinity gradient they can drive an instability known as sedimentary fingering convection. This phenomenon is thought to occur beneath sediment-rich river plumes in lakes and oceans, in the context of marine snow where decaying organic materials serve as the suspended particles, or in the atmosphere in the presence of aerosols or volcanic ash. Laboratory experiments of Houk and Green (1973) and Green (1987) have shown sedimentary fingering convection to be similar to the more commonly known thermohaline fingering convection in many ways. Here, we study the phenomenon using 3D direct numerical simulations. We find evidence for layer formation in sedimentary fingering convection in regions of parameter space where it does not occur for non-sedimentary systems. This is due to two complementary effects. Sedimentation affects the turbulent fluxes and broadens the region of parameter space unstable to the $\\gamma$-instability (Radko 2003) to include systems at larger density ratios. It also gives rise to a new layering instability that exists in $\\gamma-$stable regimes. The former is likely quite ubiquitous in geophysical systems for sufficiently large settling velocities, while the latter probably grows too slowly to be relevant, at least in the context of sediments in water.

  14. Sedimentary complexes of the cover of the Dzabkhan continental block: Different sedimentary basins and source areas

    NASA Astrophysics Data System (ADS)

    Letnikova, E. F.; Vishnevskaya, I. A.; Letnikov, F. A.; Vetrova, N. I.; Shkolnik, S. I.; Kostitsyn, Yu. A.; Karakovskii, E. A.; Reznitskii, L. Z.; Kanygina, N. A.

    2016-10-01

    The geochemical and Sm-Nd isotope characteristics of Late Precambrian and Early Cambrian sandstones previously related to the sedimentary cover of the Dzabkhan continental block are reported. It is established that the Riphean and Vendian sedimentary rocks of the Ul'zitgol'skaya and Tsaganolomskaya Formations were accumulated within the Dzabkhan continental block as a result of recycling of the terrigenous deposits formed at the expense of destruction of basement rocks and younger granite. The formation of terrigenous rocks of the Bayangol'skaya Formation after a gap in sedimentation occurred in the sedimentary basin, where only the Late Riphean formations of the juvenile crust, probably of the Dzabkhan-Mandal block were the sources, without the contribution of the ancient crustal material. The Tsaganolomskaya and Bayangol'skaya Formations were formed in different sedimentary basins and cannot be related to the same complex.

  15. Geochemistry of Fine-grained Sediments and Sedimentary Rocks

    NASA Astrophysics Data System (ADS)

    Sageman, B. B.; Lyons, T. W.

    2003-12-01

    , 1981; Berner et al., 1983; Kump et al., 2000), with a shifting emphasis toward sophisticated characterization of the linkages among solid Earth, oceans, biosphere, cryosphere, atmosphere, and climate, mediated by short- and long-term biogeochemical cycles. As a result, one of the primary objectives of current geological inquiry is improved understanding of the interconnectedness and associated feedback among the cycles of carbon, nitrogen, phosphorous, oxygen, and sulfur, and their relationship to the history of Earth's climate. This "Earth System" approach involves uniformitarian extrapolations of knowledge gained from modern environments to proxy-based interpretations of environmental change recorded in ancient strata. The strength of modern data lies with direct observations of pathways and products of physical, chemical, and biological processes, but available time-series are short relative to the response times of many of the biogeochemical systems under study. By contrast, stratigraphically constrained geological data offer time-series that encompass a much fuller range of system response. But with the enhanced breadth of temporal resolution and signal amplitude provided by ancient sedimentary records comes a caveat - we must account for the blurring of primary paleo-environmental signals by preservational artifacts and understand that proxy calibrations are extended from the modern world into a nonsubstantively uniformitarian geological past.Fortunately, detrital sedimentary rocks preserve records of multiple proxies (dependent and independent) that illuminate the processes and conditions of sediment formation, transport, deposition, and burial. An integrated multiproxy approach offers an effective tool for deconvolving the history of biogeochemical cycling of, among other things, carbon and sulfur, and for understanding the range of associated paleo-environmental conditions (e.g., levels of atmospheric oxygen and carbon dioxide, oceanic paleoredox, and

  16. Petroleum potential of the Libyan sedimentary basins

    SciTech Connect

    Hammuda, O.S.; Sbeta, A.M.

    1988-08-01

    Contrary to prevailing opinion, all Libyan sedimentary basins and the Al-Jabal Al-Akhdar platform contain prolific petroleum accumulations with very high prospectivity. A systematic review of the types of traps and pays in this central part of the southern Mediterranean province reveals great variability in reservoir and source rock characteristics. The reservoir rocks are of almost all geologic ages. The thick source rock sequences also vary in nature and organic content. The organic-rich facies have accumulated in intracratonic and passive margin basins or in marginal seas. Most of the oil discovered thus far in these basins is found in large structural traps. Future discoveries of stratigraphic traps or small structural traps will require intensified efforts and detailed studies using up-to-date multidisciplinary techniques in sedimentary tectonics, biostratigraphic facies analysis, and geochemical prospecting in order to develop a better understanding of these basins, thus improving their prospectivity.

  17. Tide-influenced sedimentary environments and facies

    SciTech Connect

    De Boer, P.L.; Van Gelder, A.; Nio, S.D.

    1988-01-01

    This volume contains examples of recent as well as fossil tide-influenced sedimentary facies. Studies of recent tidal processes and sediments provide an insight into the way in which tidal facies and sequences develop, and into the processes which are active. The studies performed on fossil rocks give information on one-to-one scale model experiments that have been executed by nature both relatively recently and in the distant past. In this work, the parallel presentation of papers on recent and fossil examples of tide-influenced sedimentary facies and environments follows the philosophy of comparative sedimentology, aiming at an understanding of both the past and the present, with the aim also, of forecasting future developments.

  18. Triple oxygen isotope variations in sedimentary rocks

    NASA Astrophysics Data System (ADS)

    Levin, Naomi E.; Raub, Timothy D.; Dauphas, Nicolas; Eiler, John M.

    2014-08-01

    Relatively large (⩾0.2‰) 17O anomalies in the geologic record have been used to recognize atmospheric processes such as photochemical reactions and to trace changes in the partial pressures of O2 and CO2 in Earth’s atmosphere through time. However, recent oxygen isotope measurements of terrestrial rocks, minerals and waters also reveal common, smaller (but statistically significant) deviations from a single mass-dependent fractionation line. These subtle anomalies have been explained through differences in mass-dependent isotopic fractionations for various equilibrium and kinetic mechanisms. Here we present triple oxygen isotope data on sedimentary silica and oxides, including Archean and Phanerozoic cherts, and iron formations. The distribution of data reflects the mass fractionation laws of low-temperature precipitation reactions during growth of authigenic minerals, variation in Δ17O of the waters from which sedimentary minerals precipitate, and equilibrium exchange after initial authigenic formation. We use these results to illustrate the potential for small, mass-dependent variations in Δ17O values of sedimentary rocks to provide constraints on the environmental and climatic conditions in which they formed.

  19. Experimental model to study sedimentary kidney stones.

    PubMed

    Grases, F; Llobera, A

    1998-01-01

    An experimental model to reproduce, to some extent, the conditions prevailing during the formation of the so-called sedimentary urinary stones, was developed. The results obtained demonstrated that in the absence of organic matter no calcium phosphate crystals were deposited in cavities with scarce liquid renovation. Nevertheless, in such case a regular hydroxyapatite layer was developed on the walls around the cavity. The presence of crystallization inhibitors cannot stop indefinitely the crystal development. Therefore, phytate manifested important inhibitory effects in concentrations normally found in urine (0.77-1.54 x 10(-6) mol/l), whereas citrate only manifested important inhibitory effects when found at high urinary concentrations (2.64 x 10(-3) mol/l). When mucin (a glycoprotein) was present in the urine, a clear deposit of calcified organic material was formed. The organic matter appeared mixed with the spherulites of hydroxyapatite, this demonstrating the capacity of the glycoprotein agglomerates to act as heterogeneous nucleants of calcium salts and their important role in the formation of sedimentary stones. The structural features of the obtained in vitro deposits were compared with the fine structure of human sedimentary phosphate calculi. Scanning electron microscopy images demonstrated a good correspondence between in vitro experiments and in vivo observations.

  20. Rare earth elements and neodymium isotopes in sedimentary organic matter

    NASA Astrophysics Data System (ADS)

    Freslon, Nicolas; Bayon, Germain; Toucanne, Samuel; Bermell, Sylvain; Bollinger, Claire; Chéron, Sandrine; Etoubleau, Joel; Germain, Yoan; Khripounoff, Alexis; Ponzevera, Emmanuel; Rouget, Marie-Laure

    2014-09-01

    We report rare earth element (REE) and neodymium (Nd) isotope data for the organic fraction of sediments collected from various depositional environments, i.e. rivers (n = 25), estuaries (n = 18), open-ocean settings (n = 15), and cold seeps (n = 12). Sedimentary organic matter (SOM) was extracted using a mixed hydrogen peroxide/nitric acid solution (20%-H2O2-0.02 M-HNO3), after removal of carbonate and oxy-hydroxide phases with dilute hydrochloric acid (0.25 M-HCl). A series of experimental tests indicate that extraction of sedimentary organic compounds using H2O2 may be complicated occasionally by partial dissolution of sulphide minerals and residual carbonates. However, this contamination is expected to be minor for REE because measured concentrations in H2O2 leachates are about two-orders of magnitude higher than in the above mentioned phases. The mean REE concentrations determined in the H2O2 leachates for samples from rivers, estuaries, coastal seas and open-ocean settings yield relatively similar levels, with ΣREE = 109 ± 86 ppm (mean ± s; n = 58). The organic fractions leached from cold seep sediments display even higher concentration levels (285 ± 150 ppm; mean ± s; n = 12). The H2O2 leachates for most sediments exhibit remarkably similar shale-normalized REE patterns, all characterized by a mid-REE enrichment compared to the other REE. This suggests that the distribution of REE in leached sedimentary organic phases is controlled primarily by biogeochemical processes, rather than by the composition of the source from which they derive (e.g. pore, river or sea-water). The Nd isotopic compositions for organic phases leached from river sediments are very similar to those for the corresponding detrital fractions. In contrast, the SOM extracted from marine sediments display εNd values that typically range between the εNd signatures for terrestrial organic matter (inferred from the analysis of the sedimentary detrital fractions) and marine organic matter

  1. Sedimentary input of trace metals from the Chukchi Shelf

    NASA Astrophysics Data System (ADS)

    Aguilar-Islas, A. M.; Seguré, M.; Rember, R.; Nishino, S.

    2014-12-01

    The distribution of trace metals in the Arctic Ocean has implications for their global cycles, yet until recently few trace metal observations were available from this rapidly changing ocean. Profiles of dissolved Fe from recent Japanese field efforts in the Western Canada Basin (2008, 2010) indicate the broad Chukchi Shelf as a source of Fe to the halocline of the Western Canada Basin. Here we present dissolved and particulate data for crustal (Al, Mn, Fe) and non-crustal elements (Co, Cu, Zn) from the productive Chukchi Sea to characterize the sedimentary input of these metals to shelf waters contributing to the halocline layer of the Canada Basin. Water column profiles were collected in late summer 2013 onboard the R/V Mirai at 10 stations from the Bering Strait to the slope, and at a time-series (10 days) station located over the outer shelf. A narrow and variable (5-10 m) benthic boundary layer was sampled at the time-series station with highly elevated dissolved and suspended particulate metal concentrations. High metal concentrations were also observed in the subsurface at a station over Barrow Canyon where mixing is enhanced. Reactivity of suspended particulate metals was determined by the leachable vs. refractory fractions. Metal concentrations were determined by ICP-MS. Trace metal transport from the shelf to the interior will be discussed in context with shelf mechanisms contributing to this export, and to expected future changes in the Arctic Ocean.

  2. Sedimentary fill and stratigraphic traps of Porcupine basin, offshore Ireland

    SciTech Connect

    Macurda, D.B. Jr.

    1986-05-01

    The Porcupine basin, off the southwest coast of Ireland, is a triangular north-south re-entrant into the present-day continental shelf. This aulacogen was formed in the Jurassic during the opening of the North Atlantic. A seismic stratigraphic investigation of the southern part of the basin has shown the complex evolution of the sedimentary fill from shallow to deep water facies, resulting in several stratigraphic traps. The central axis of the basin is dominated by a volcanic ridge. Part of the early sedimentary fill was intermittently covered by volcanic flows. The final stage of thin initial siliciclastic infill was the development of an extensive alluvial fan or fan-delta complex along the eastern basin margin. Aerially extensive carbonate sedimentation occurred during the Cretaceous, including a north-south reef tract more than 20 km wide in the eastern part of the basin. Increased subsidence resulted in the deposition of deep water siliciclastics in the Tertiary. The most prominent of these is a series of lower Tertiary submarine fans that were sourced from the western, northern, and eastern margins of the aulacogen. The early portions of the fans correlate well basin-wide; their later history is much more complex, with younger lobes up to 25 km wide developing south of their precursors. Subsequent onlap fill deposits provide an excellent seal. Sedimentation in the late Tertiary has included both high-energy and low-energy deep water deposits. The complex fill of the aulacogen has set up several stratigraphic plays, including carbonate reefs, alluvial fans of fan deltas, and submarine fans. Seismic amplitude anomalies in the latter suggest the heat flow has been sufficient to generate hydrocarbons to fill some of the traps.

  3. Estimation of sedimentary proxy records together with associated uncertainty

    NASA Astrophysics Data System (ADS)

    Goswami, B.; Heitzig, J.; Rehfeld, K.; Marwan, N.; Ambili, A.; Prasad, S.; Kurths, J.

    2014-06-01

    Sedimentary proxy records constitute a significant portion of the recorded evidence that allow us to investigate paleoclimatic conditions and variability. However, uncertainties in the dating of proxy archives limit our ability to fix the timing of past events and interpret proxy record inter-comparisons. While there are various age-modeling approaches to improve the estimation of the age-depth relations of archives, relatively less focus has been given to the propagation of the age (and radiocarbon calibration) uncertainties into the final proxy record. We present a generic Bayesian framework to estimate proxy records along with their associated uncertainty starting with the radiometric age-depth and proxy-depth measurements, and a radiometric calibration curve if required. We provide analytical expressions for the posterior proxy probability distributions at any given calendar age, from which the expected proxy values and their uncertainty can be estimated. We illustrate our method using two synthetic datasets and then use it to construct the proxy records for groundwater inflow and surface erosion from Lonar lake in central India. Our analysis reveals interrelations between the uncertainty of the proxy record over time and the variance of proxy along the depth of the archive. For the Lonar lake proxies, we show that, rather than the age uncertainties, it is the proxy variance combined with calibration uncertainty that accounts for most of the final uncertainty. We represent the proxy records as probability distributions on a precise, error-free time scale that makes further time series analyses and inter-comparison of proxies relatively simpler and clearer. Our approach provides a coherent understanding of age uncertainties within sedimentary proxy records that involve radiometric dating. It can be potentially used within existing age modeling structures to bring forth a reliable and consistent framework for proxy record estimation.

  4. Estimation of sedimentary proxy records together with associated uncertainty

    NASA Astrophysics Data System (ADS)

    Goswami, B.; Heitzig, J.; Rehfeld, K.; Marwan, N.; Anoop, A.; Prasad, S.; Kurths, J.

    2014-11-01

    Sedimentary proxy records constitute a significant portion of the recorded evidence that allows us to investigate paleoclimatic conditions and variability. However, uncertainties in the dating of proxy archives limit our ability to fix the timing of past events and interpret proxy record intercomparisons. While there are various age-modeling approaches to improve the estimation of the age-depth relations of archives, relatively little focus has been placed on the propagation of the age (and radiocarbon calibration) uncertainties into the final proxy record. We present a generic Bayesian framework to estimate proxy records along with their associated uncertainty, starting with the radiometric age-depth and proxy-depth measurements, and a radiometric calibration curve if required. We provide analytical expressions for the posterior proxy probability distributions at any given calendar age, from which the expected proxy values and their uncertainty can be estimated. We illustrate our method using two synthetic data sets and then use it to construct the proxy records for groundwater inflow and surface erosion from Lonar lake in central India. Our analysis reveals interrelations between the uncertainty of the proxy record over time and the variance of proxies along the depth of the archive. For the Lonar lake proxies, we show that, rather than the age uncertainties, it is the proxy variance combined with calibration uncertainty that accounts for most of the final uncertainty. We represent the proxy records as probability distributions on a precise, error-free timescale that makes further time series analyses and intercomparisons of proxies relatively simple and clear. Our approach provides a coherent understanding of age uncertainties within sedimentary proxy records that involve radiometric dating. It can be potentially used within existing age modeling structures to bring forth a reliable and consistent framework for proxy record estimation.

  5. The Trenton Group (Upper Ordovician Series) of eastern North America

    SciTech Connect

    Keith, B.D.

    1989-01-01

    The Trenton Group of eastern North America is a predominately carbonate series of sedimentary rocks that contains major oil and gas deposits. The 18 papers contained in this volume discuss the stratigraphy, depositional environment, tectonics, and petroleum and natural gas exploration in this sedimentary sequence. Each of the papers has been abstracted and indexed for the U.S. Department of Energy's Energy Data Base.

  6. Utilizing a seismoacoustic complex for the study of the upper sedimentary stratum and seafloor relief in East Arctic

    NASA Astrophysics Data System (ADS)

    Dmitrevskiy, N. N.; Ananyev, R. A.; Libina, N. V.; Roslyakov, A. G.

    2013-05-01

    The paper describes a high-resolution seismoacoustic complex for studying the upper sedimentary stratum and seafloor relief. The described complex was used during the 57th cruise of the R/V Akademik M.A. Lavrent'ev in the East Siberian and Laptev seas in the autumn of 2011. The combination of an SES-2000 narrow-beam parametric subbottom profiler and a Gidra 250/500 sidescan sonar has enabled obtaining a series of unique data on the structure of the sedimentary layers and the seafloor relief.

  7. Phanerozoic cycles of sedimentary carbon and sulfur.

    PubMed

    Garrels, R M; Lerman, A

    1981-08-01

    A reservoir model of a Recent steady-state sedimentary system in which the reduced sulfur and oxidized sulfur reservoirs were coupled with the oxidized carbon and reduced carbon reservoirs was constructed. The time curve of the sulfur isotope ratios of the sedimentary sulfate reservoir was used to drive the model back to the beginning of Cambrian time (600 million years ago), producing the reservoir sizes and isotope values and material fluxes of the carbon-sulfur system. The predicted values of carbon isotope ratios of the carbonate reservoir agree well with observed values, showing that the model is basically sound. Some general conclusions from this success are (i) material flux rates in the carbon-oxygen-sulfur system of the geologic past (averaged over tens of millions of years) lie within about a factor of 2 of Recent rates. (ii) The oxidation-reduction balances of Phanerozoic time were dominated by reciprocal relationships between carbon and sulfur compounds. (iii) The rate of production of atmospheric oxygen by storage in sediments of organic carbon of photosynthetic origin increased from the Cambrian Period to the Permian Period and declined somewhat from the Permian Period to the Present. (iv) The storage of oxygen in oxidized sulfur compounds kept pace (within the limits of the data) with oxygen production. (v) Transfer of oxygen from CO(2) to SO(4) from the Cambrian to the Permian Period was several times the Recent free oxygen content of the atmosphere.

  8. African sedimentary basins - Tectonic controls on prospectivity

    SciTech Connect

    Bunter, M.A.G.; Crossley, R.; Hammill, M.; Jones, P.W.; Morgan, R.K.; Needham, D.T.; Spaargaren, F.A. )

    1991-03-01

    An important prerequisite for the evaluation of any sedimentary basin is the understanding of its regional tectonic setting. This is especially so in the underexplored regions of Africa. The majority of African sedimentary basins developed in an extensional setting although some have undergone subsequent compressional or transpressional deformation. The geometry and evolution of these basins is often influenced by basement structure. The extensional phase of basin development controls not only the distribution of syn-rift sediments but also the magnitude of post-rift regional subsidence and the preservation or removal of pre-rift sediments. This has important consequences for exploration models of syn-rift and pre-rift source rocks and reservoirs. Post-rift basin inversion and uplift provide crucial controls on the preservation of mature source rocks and quality of reservoirs. The distribution, nature, timing, and possible mechanisms of this uplift in Africa will be addressed. The hydrocarbon prospectivity of African basis appears to be highly variable although the limited exploration of some regions makes the exact extent of this variability unclear. Basins considered potentially prospective range from late Precambrian to Tertiary in age. The various tectonic controls outlined above, and criteria for the evaluation of underexplored areas, will be demonstrated by reference to basins studied by The Robertson Group. Examples described include basins from Bagon, Angola, Namibia, East Africa, Tertiary Rift and Karoo Rifts, and North Africa (Sudan, Egypt, Algeria, and Morocco).

  9. Geothermal resources of California sedimentary basins

    USGS Publications Warehouse

    Williams, C.F.; Grubb, F.V.; Galanis, S.P.

    2004-01-01

    The 2004 Department of Energy (DOE) Strategic Plan for geothermal energy calls for expanding the geothermal resource base of the United States to 40,000 MW of electric power generating potential. This will require advances in technologies for exploiting unconventional geothermal resources, including Enhanced Geothermal Systems (EGS) and geopressured geothermal. An investigation of thermal conditions in California sedimentary basins through new temperature and heat flow measurements reveals significant geothermal potential in some areas. In many of the basins, the combined cooling effects of recent tectonic and sedimentary processes result in relatively low (<60 mW/m2) heat flow and geothermal gradients. For example, temperatures in the upper 3 km of San Joaquin, Sacramento and Ventura basins are typically less than 125??C and do not reach 200??c by 5 km. By contrast, in the Cuyama, Santa Maria and western Los Angeles basins, heat flow exceeds 80 mW/m2 and temperatures near or above 200??C occur at 4 to 5 km depth, which represents thermal conditions equivalent to or hotter than those encountered at the Soultz EGS geothermal site in Europe. Although the extractable geothermal energy contained in these basins is not large relative to the major California producing geothermal fields at The Geysers or Salton Sea, the collocation in the Los Angeles basin of a substantial petroleum extraction infrastructure and a major metropolitan area may make it attractive for eventual geothermal development as EGS technology matures.

  10. The sedimentary structure of linear sand dunes

    PubMed

    Bristow; Bailey; Lancaster

    2000-07-06

    Linear sand dunes--dunes that extend parallel to each other rather than in star-like or crescentic forms--are the most abundant type of desert sand dune. But because their development and their internal structure are poorly understood, they are rarely recognized in the rock record. Models of linear dune development have not been able to take into account the sub-surface structure of existing dunes, but have relied instead either on the extrapolation of short-term measurements of winds and sediment transport or on observations of near-surface internal sedimentary structures. From such studies, it has not been clear if linear dunes can migrate laterally. Here we present images produced by ground penetrating radar showing the three-dimensional sedimentary structure of a linear dune in the Namib sand sea, where some of the world's largest linear dunes are situated. These profiles show clear evidence for lateral migration in a linear dune. Moreover, the migration of a sinuous crest-line along the dune produces divergent sets of cross-stratification, which can become stacked as the dune height increases, and large linear dunes can support superimposed dunes that produce stacked sets of trough cross-stratification. These clear structural signatures of linear dunes should facilitate their recognition in geological records.

  11. n-Alkane lipid biomarkers in loess: post-sedimentary or syn-sedimentary?

    NASA Astrophysics Data System (ADS)

    Zech, Michael; Kreutzer, Sebastian; Goslar, Tomasz; Meszner, Sascha; Krause, Tobias; Faust, Dominik; Fuchs, Markus

    2013-04-01

    There is an ongoing discussion whether n-alkane biomarkers - and organic matter (OM) from loess in general - reflect a syn-sedimentary paleoenvironmental and paleoclimate signal or whether they are significantly a post-sedimentary feature contaminated by root-derived OM (Zech et al., 2012, 2013; Wiesenberg and Gocke, 2013). We present first radiocarbon data for the n-alkane fraction of lipid extracts and for the first time luminescence ages for the Middle to Late Weichselian loess-paleosol sequence of Gleina in Saxony, Germany. Comparison of these biomarker ages with sedimentation ages as assessed by optically stimulated luminescence (OSL) dating shows that one n-alkane sample features a syn-sedimentary age (14C: 29.2 ± 1.4 kyr calBP versus OSL: 27.3 ± 3.0 kyr). By contrast, the 14C ages derived from the other n-alkane samples are clearly younger (20.3 ± 0.7 kyr calBP, 22.1 ± 0.7 kyr calBP and 29.8 ± 1.4 kyr calBP) than the corresponding OSL ages (26.6 ± 3.1 kyr, 32.0 ± 3.5 kyr and 45.6 ± 5.3 kyr). This finding suggests that a post-sedimentary n-alkane contamination presumably by roots has occurred. In order to estimate the post-sedimentary n-alkane contamination more quantitatively, we applied a 14C mass balance calculation based on the measured pMC (percent modern carbon) values, the calculated syn-sedimentary pMC values and pMC values suspected to reflect likely time points of post-sedimentary contamination (modern, last decades, 3 kyr, 6 kyr and 9 kyr). Accordingly, modern and last decadal root-contamination would account for up to 7%, a 3 kyr old root-contamination for up to 10%, and an Early and Middle Holocene root-contamination for up to 20% of the total sedimentary n-alkane pool. We acknowledge and encourage that these first radiocarbon results need further confirmation both from other loess-paleosol sequences and for different biomarkers, e.g. carboxylic acids or alcohols as further lipid biomarkers. Zech, M., Kreutzer, S., Goslar, T., Meszner, S

  12. Quantitative compositional analysis of sedimentary materials using thermal emission spectroscopy: 1. Application to sedimentary rocks

    NASA Astrophysics Data System (ADS)

    Thorpe, Michael T.; Rogers, A. Deanne; Bristow, Thomas F.; Pan, Cong

    2015-11-01

    Thermal emission spectroscopy is used to determine the mineralogy of sandstone and mudstone rocks as part of an investigation of linear spectral mixing between sedimentary constituent phases. With widespread occurrences of sedimentary rocks on the surface of Mars, critical examination of the accuracy associated with quantitative models of mineral abundances derived from thermal emission spectra of sedimentary materials is necessary. Although thermal emission spectroscopy has been previously proven to be a viable technique to obtain quantitative mineralogy from igneous and metamorphic materials, sedimentary rocks, with natural variation of composition, compaction, and grain size, have yet to be examined. In this work, we present an analysis of the thermal emission spectral (~270-1650 cm-1) characteristics of a suite of 13 sandstones and 14 mudstones. X-ray diffraction and traditional point counting procedures were all evaluated in comparison with thermal emission spectroscopy. Results from this work are consistent with previous thermal emission spectroscopy studies and indicate that bulk rock mineral abundances can be estimated within 11.2% for detrital grains (i.e., quartz and feldspars) and 14.8% for all other mineral phases present in both sandstones and mudstones, in comparison to common in situ techniques used for determining bulk rock composition. Clay-sized to fine silt-sized grained phase identification is less accurate, with differences from the known ranging from ~5 to 24% on average. Nevertheless, linear least squares modeling of thermal emission spectra is an advantageous technique for determining abundances of detrital grains and sedimentary matrix and for providing a rapid classification of clastic rocks.

  13. Age and sedimentary record of inland eolian sediments in Lithuania, NE European Sand Belt

    NASA Astrophysics Data System (ADS)

    Kalińska-Nartiša, Edyta; Thiel, Christine; Nartišs, Māris; Buylaert, Jan-Pieter; Murray, Andrew S.

    2015-07-01

    We present a study based on four inland eolian locations in Eastern, Central and Southeastern Lithuania belonging to the northeastern part of the 'European Sand Belt' (ESB). Although there have been several previous studies of the ESB, this north-eastern extension has not been investigated before in any detail. The sedimentary structural-textural features are investigated and a chronology was derived using optically stimulated luminescence on both quartz and feldspar. The sedimentary structures and the rounding and surface characteristics of the quartz grains argue for a predominance of eolian transport. Additionally, some structural alternations and a significant contribution of non-eolian grains are interpreted as inherited local glacial/glaciofluvial-bearing lithologies. Three main (glaciolacustrine-) eolian phases are distinguished based on the position in the landscape and the luminescence ages: (1) An older eolian series around 15 to 16 ka, possibly correlated with the cold GS-2a event according to the GRIP stratigraphy, and (2) a younger eolian series around 14.0 ka, possibly representing the GI-1d and 1c events. The older eolian series is underlain by (3) a glaciolacustrine-eolian series for which the period of deposition remains uncertain due to the significant discrepancy between the ages based on quartz and feldspar.

  14. Copper Deposits in Sedimentary and Volcanogenic Rocks

    USGS Publications Warehouse

    Tourtelot, Elizabeth B.; Vine, James David

    1976-01-01

    Copper deposits occur in sedimentary and volcanogenic rocks within a wide variety of geologic environments where there may be little or no evidence of hydrothermal alteration. Some deposits may be hypogene and have a deep-seated source for the ore fluids, but because of rapid cooling and dilution during syngenetic deposition on the ocean floor, the resulting deposits are not associated with hydrothermal alteration. Many of these deposits are formed at or near major tectonic features on the Earth's crust, including plate boundaries, rift valleys, and island arcs. The resulting ore bodies may be stratabound and either massive or disseminated. Other deposits form in rocks deposited in shallow-marine, deltaic, and nonmarine environments by the movement and reaction of interstratal brines whose metal content is derived from buried sedimentary and volcanic rocks. Some of the world's largest copper deposits were probably formed in this manner. This process we regard as diagenetic, but some would regard it as syngenetic, if the ore metals are derived from disseminated metal in the host-rock sequence, and others would regard the process as epigenetic, if there is demonstrable evidence of ore cutting across bedding. Because the oxidation associated with diagenetic red beds releases copper to ground-water solutions, red rocks and copper deposits are commonly associated. However, the ultimate size, shape, and mineral zoning of a deposit result from local conditions at the site of deposition - a logjam in fluvial channel sandstone may result in an irregular tabular body of limited size; a petroleum-water interface in an oil pool may result in a copper deposit limited by the size and shape of the petroleum reservoir; a persistent thin bed of black shale may result in a copper deposit the size and shape of that single bed. The process of supergene enrichment has been largely overlooked in descriptions of copper deposits in sedimentary rocks. However, supergene processes may be

  15. Remote sensing of some sedimentary rocks.

    NASA Technical Reports Server (NTRS)

    Brennan, P. A.; Lintz, J., Jr.

    1971-01-01

    Sedimentary rocks including varying sized clastics and carbonates were overflown by aircraft between 1966 and 1971 producing data in the ultraviolet to microwave regions of the electromagnetic spectrum. This paper reports that multispectral analysis increases the ease and rapidity of discrimination of rock types having subtle differences in physical characteristics, but fails to enhance and may degrade distinctions where physical characteristics are significantly different. Brief resumes of color and color IR photographic data are presented. Thermal infrared is found to be useful in the mapping of rock units, but limitations such as moisture variation, soil cover, and vegetation may exceed in one formation the distinction between differing lithologies. A brief review of previously published SLAR data is included for completeness. Remote sensing techniques should reduce field geological effort by as much as 50%.

  16. Sedimentary processes and crustal cycling on Venus

    NASA Technical Reports Server (NTRS)

    Warner, J. L.

    1983-01-01

    Sediment exists on the Venus surface. It is observed in Venera images between outcrops and boulders of sedimentary rocks. Sediment is produced by pyroclastic volcanism and chemical weathering. Chemical weathering is driven by an enhanced activity of water and an elevated surface temperature. Sediment is transported by wind action and lithified by cementration and diagenesis. Cementation may be by carbonate or silica cement; diagenesis may be products of chemical weathering acting as cement, or by compaction and recrystallization of sediment into a texture with interlocking grains. Sediment may be transported from the top of sialic continents (such as Ishtar) to the modal plains where it is deposited, lithified, and integrated into thy local crust. As new layers are added, the bottom of the crust melts and is, in part, returned to the mantle. A steady-state chemical exchange might exist by this mechanism of crustal cycling that links atmosphere, continents, modal plains, and mantle.

  17. Sedimentary deposits in response to rift geometry in Malawi, Africa

    SciTech Connect

    Bishop, M.G. )

    1991-03-01

    Sedimentary deposits of the Malawi continental rift basin are a direct result of topography and tectonics unique to rift structure. Recent models describe rifts as asymmetric half-graben connected in series by transfer of accommodation zones. Half-graben consist of roughly parallel, tilted fault blocks stepping up from the bounding fault zone where maximum subsidence occurs. The rift becomes a local baselevel and depocenter as regional drainage is shed away by the rift shoulders. Most of the sediments are derived locally due to internal drainage of connected basins, individual basins, and individual fault blocks. The patterns of sedimentation and facies associations depend on structural position at both fault block and half-graben scales. Drainage is directed and dammed by tilted fault blocks. Forward-tilted fault blocks form basinward-thickening sediment wedges filled with facies of axial fluvial systems, alluvial fault-scarp fans, and ponded swamp and lake deposits. These deposits are asymmetrically shifted toward the controlling fault and onlap the upthrown side of the block, ordinarily the site of erosion or nondeposition. Rivers entering the lake on back tilted fault blocks form large deltas resulting in basinward fining and thinning sediment wedges. Lacustrine, nearshore, shoreline, and lake shore plain deposits over multiple fault blocks record lake levels, water chemistry, and tectonic episodes. Tectonic movement periodically changes the basin depth, configuration, and baselevel. This movement results in widespread unconformities deposition and reworking of sediments within the rift.

  18. Thermal evolution of sedimentary basins in Alaska

    USGS Publications Warehouse

    Johnsson, Mark J.; Howell, D.G.

    1996-01-01

    The complex tectonic collage of Alaska is reflected in the conjunction of rocks of widely varying thermal maturity. Indicators of the level of thermal maturity of rocks exposed at the surface, such as vitrinite reflectance and conodont color alteration index, can help constrain the tectonic evolution of such complex regions and, when combined with petrographic, modern heat flow, thermogeochronologic, and isotopic data, allow for the detailed evaluation of a region?s burial and uplift history. We have collected and assembled nearly 10,000 vitrinite-reflectance and conodont-color-alteration index values from the literature, previous U.S. Geological Survey investigations, and our own studies in Alaska. This database allows for the first synthesis of thermal maturity on a broadly regional scale. Post-accretionary sedimentary basins in Alaska show wide variability in terms of thermal maturity. The Tertiary interior basins, as well as some of the forearc and backarc basins associated with the Aleutian Arc, are presently at their greatest depth of burial, with immature rocks exposed at the surface. Other basins, such as some backarc basins on the Alaska Peninsula, show higher thermal maturities, indicating modest uplift, perhaps in conjunction with higher geothermal gradients related to the arc itself. Cretaceous ?flysch? basins, such as the Yukon-Koyukuk basin, are at much higher thermal maturity, reflecting great amounts of uplift perhaps associated with compressional regimes generated through terrane accretion. Many sedimentary basins in Alaska, such as the Yukon-Koyukuk and Colville basins, show higher thermal maturity at basin margins, perhaps reflecting greater uplift of the margins in response to isostatic unloading, owing to erosion of the hinterland adjacent to the basin or to compressional stresses adjacent to basin margins.

  19. Clastic sedimentary rocks of the Michipicoten Volcanic-sedimentary belt, Wawa, Ontario

    NASA Technical Reports Server (NTRS)

    Ojakangas, R. W.

    1983-01-01

    The Wawa area, part of the Michipicoten greenstone belt, contains rock assemblages representative of volcanic sedimentary accumulations elsewhere on the shield. Three mafic to felsic metavolcanic sequences and cogenetic granitic rocks range in age from 2749 + or - 2Ma to 2696 + or - 2Ma. Metasedimentary rocks occur between the metavolcanic sequences. The total thickness of the supracrustal rocks may be 10,000 m. Most rocks have been metamorphosed under greenschist conditions. The belt has been studied earlier and is currently being remapped by Sage. The sedimentrologic work has been briefly summarized; two mainfacies associations of clastic sedimentary rocks are present - a Resedimented (Turbidite) Facies Association and a Nonmarine (Alluvial Fan Fluvial) Facies Association.

  20. Archean sedimentary styles and early crustal evolution

    NASA Technical Reports Server (NTRS)

    Lowe, D. R.

    1986-01-01

    The distinctions between and implications of early and late Archean sedimentary styles are presented. Early Archean greenstone belts, such as the Barberton of South Africa and those in the eastern Pilbar Block of Australia are characterized by fresh or slightly reworked pyroclastic debris, orthochemical sediments such as carbonates, evaporites, and silica, and biogenic deposits including cherts and stromatolitic units. Terrigenous deposits are rare, and it is suggested that early Archean sediments were deposited on shallow simatic platforms, with little or no components derived from sialic sources. In contrast, late Archean greenstone belts in the Canadian Shield and the Yilgarn Block of Australia contain coarse terrigenous clastic rocks including conglomerate, sandstone, and shale derived largely from sialic basement. Deposition appears to have taken place in deepwater, tectonically unstable environments. These observations are interpreted to indicate that the early Archean greenstone belts formed as anorogenic, shallow water, simatic platforms, with little or no underlying or adjacent continental crust, an environment similar to modern oceanic islands formed over hot spots.

  1. Investigating Coccolithophorid Biology in the Sedimentary Laboratory

    NASA Astrophysics Data System (ADS)

    McClelland, H. L. O.; Barbarin, N.; Beaufort, L.; Hermoso, M.; Rickaby, R. E. M.

    2014-12-01

    Coccolithophores are the ocean's dominant calcifying phytoplankton; they play an important, but poorly understood, role in long-term biogeochemical climatic feedbacks. Calcite producing marine organisms are likely to calcify less in a future world where higher carbon dioxide concentrations will lead to ocean acidification (OA), but coccolithophores may be the exception. In coccolithophores calcification occurs in an intracellular vesicle, where the site of calcite precipitation is buffered from the external environment and is subject to a uniquely high degree of biological control. Culture manipulation experiments mimicking the effects of OA in the laboratory have yielded empirical evidence for phenotypic plasticity, competition and evolutionary adaptation in asexual populations. However, the extent to which these results are representative of natural populations, and of the response over timescales of greater than a few hundred generations, is unclear. Here we describe a new sediment-based proxy for the PIC:POC (particulate inorganic to particulate organic carbon ratio) of coccolithophore biomass, which is equivalent to the fractional energy contribution to calcification at constant pH, and a biologically meaningful measure of the organism's tendency to calcify. Employing the geological record as a laboratory, we apply this proxy to sedimentary material from the southern Pacific Ocean to investigate the integrated response of real ancient coccolithophore populations to environmental change over many thousands of years. Our results provide a new perspective on phenotypic change in real populations of coccolithophorid algae over long timescales.

  2. Sedimentary Geothermal Feasibility Study: October 2016

    SciTech Connect

    Augustine, Chad; Zerpa, Luis

    2017-01-01

    The objective of this project is to analyze the feasibility of commercial geothermal projects using numerical reservoir simulation, considering a sedimentary reservoir with low permeability that requires productivity enhancement. A commercial thermal reservoir simulator (STARS, from Computer Modeling Group, CMG) is used in this work for numerical modeling. In the first stage of this project (FY14), a hypothetical numerical reservoir model was developed, and validated against an analytical solution. The following model parameters were considered to obtain an acceptable match between the numerical and analytical solutions: grid block size, time step and reservoir areal dimensions; the latter related to boundary effects on the numerical solution. Systematic model runs showed that insufficient grid sizing generates numerical dispersion that causes the numerical model to underestimate the thermal breakthrough time compared to the analytic model. As grid sizing is decreased, the model results converge on a solution. Likewise, insufficient reservoir model area introduces boundary effects in the numerical solution that cause the model results to differ from the analytical solution.

  3. Sedimentary organic molecules: Origins and information content

    NASA Technical Reports Server (NTRS)

    Hayes, J. M.; Freeman, K. H.

    1991-01-01

    To progress in the study of organic geochemistry, we must dissect the processes controlling the composition of sedimentary organic matter. Structurally, this has proven difficult. Individual biomarkers can often be recognized, but their contribution to total organic materials is small, and their presence does not imply that their biochemical cell mates have survived. We are finding, however, that a combination of structural and isotopic lines of evidence provides new information. A starting point is provided by the isotopic compositions of primary products (degradation products of chlorophylls, alkenones derived from coccoliths). We find strong evidence that the isotopic difference between primary carbonate and algal organic material can be interpreted in terms of the concentration of dissolved CO2. Moreover, the isotopic difference between primary and total organic carbon can be interpreted in terms of characteristic isotopic shifts imposed by secondary processes (responsive, for example, to O2 levels in the depositional environment. In favorable cases, isotopic compositions of a variety of secondary products can be interpreted in terms of flows of carbon, and, therefore, in terms of specific processes and environmental conditions within the depositional environment.

  4. Microbial shaping of sedimentary wrinkle structures

    NASA Astrophysics Data System (ADS)

    Mariotti, G.; Pruss, S. B.; Perron, J. T.; Bosak, T.

    2014-10-01

    Wrinkle structures on sandy bed surfaces were present in some of the earliest sedimentary environments, but are rare in modern environments. These enigmatic millimetre- to centimetre-scale ridges or pits are particularly common in sediments that harbour trace fossils and imprints of early animals, and appeared in the aftermath of some large mass extinctions. Wrinkle structures have been interpreted as possible remnants of microbial mats, but the formation mechanism and associated palaeoenvironmental and palaeoecological implications of these structures remain debated. Here we show that microbial aggregates can form wrinkle structures on a bed of bare sand in wave tank experiments. Waves with a small orbital amplitude at the bed surface do not move sand grains directly. However, they move millimetre-size, light microbial fragments and thereby produce linear sand ridges and rounded scour pits at the wavelengths observed in nature within hours. We conclude that wrinkle structures are morphological biosignatures that form at the sediment-water interface in wave-dominated environments, and not beneath microbial mats as previously thought. During early animal evolution, grazing by eukaryotic organisms may have temporarily increased the abundance of microbial fragments and thus the production of wrinkle structures.

  5. Simulation model of clastic sedimentary processes

    SciTech Connect

    Tetzlaff, D.M.

    1987-01-01

    This dissertation describes SEDSIM, a computer model that simulates erosion, transport, and deposition of clastic sediments by free-surface flow in natural environments. SEDSIM is deterministic and is applicable to sedimentary processes in rivers, deltas, continental shelves, submarine canyons, and turbidite fans. The model is used to perform experiments in clastic sedimentation. Computer experimentation is limited by computing power available, but is free from scaling problems associated with laboratory experiments. SEDSIM responds to information provided to it at the outset of a simulation experiment, including topography, subsurface configuration, physical parameters of fluid and sediment, and characteristics of sediment sources. Extensive computer graphics are incorporated in SEDSIM. The user can display the three-dimensional geometry of simulated deposits in the form of successions of contour maps, perspective diagrams, vector plots of current velocities, and vertical sections of any azimuth orientation. The sections show both sediment age and composition. SEDSIM works realistically with processes involving channel shifting and topographic changes. Example applications include simulation of an ancient submarine canyon carved into a Cretaceous sequence in the National Petroleum Reserve in Alaska, known mainly from seismic sections and a sequence of Tertiary age in the Golden Meadow oil field of Louisiana, known principally from well logs.

  6. The Sedimentary Signature of Recent Tsunamis

    NASA Astrophysics Data System (ADS)

    Jaffe, B. E.; Peters, R. B.; Richmond, B. M.

    2011-12-01

    The 2011 Tohoku-Oki tsunami, which killed approximately 21,000 and at most locations in northeastern Japan inundated farther inland than historic tsunamis, underscores the need to use the geologic record for an accurate assessment of tsunami hazard. The ability to identify tsunami deposits, the primary geologic record of tsunamis, has greatly improved as teams of scientists have collected data on deposit and flow characteristics as soon as possible after recent tsunamis. Although sand and boulder transport and deposition were reported for the 1946 tsunami in Hawaii, detailed post-tsunami sedimentological surveys were not conducted until the early 1990s. Since then, documenting sedimentary deposits has been part of the scientific response to nearly all major tsunamis. In total, there have been detailed geologic surveys of more than a dozen tsunamis; these surveys have increased in scope and sophistication. Sandy tsunami deposits on coastal plains have common characteristics (Peters and Jaffe, 2010). They are typically deposited in sheets that drape pre-existing topography. Deposits are absent near the shoreline in a zone of bypass or erosion that increases in width with tsunami size and can extend more than 100 m inland. Deposits generally thin landward, typically are less than 30 cm thick near the shoreline, but in rare cases may be more than a meter thick locally in depressions and bends in rivers. Conversely deposits are thinner on local topographic highs, such as ridges. Deposits are comprised of layers that are interpreted as forming during half-wave cycles. Typically there are 1 to 4 layers, each with a sharp lower contact. Each layer's lower portion is often either massive or inversely graded and its top suspension graded, a form of normal grading created when sediment in suspension settles out of the water column as the flow speed decreases. In muddy environments, deposits commonly contain mud and soil rip-up clasts and mud often caps the deposits or

  7. Mid-Latitude Sedimentary Rock: Spallanzani Crater

    NASA Technical Reports Server (NTRS)

    2001-01-01

    [figure removed for brevity, see original site]

    Although most of the best examples of layered sedimentary rock seen on Mars are found at equatorial and sub-tropical latitudes, a few locations seen at mid- and high-latitudes suggest that layered rocks are probably more common than we can actually see from orbit. One extremely good example of these 'atypical' layered rock exposures is found in the 72 km-diameter (45 miles) crater, Spallanzani (58.4oS, 273.5oW). Located southeast of Hellas Planitia, the crater is named for the 18th Century Italian biologist, Lazzaro Spallanzani (1729-1799). Picture A presents a composite of the best Viking orbiter image (VO2-504B55) of the region with 4 pictures obtained June 1999 through January 2001 by the Mars Global Surveyor Mars Orbiter Camera (MOC). Each MOC narrow angle image is 3 km across. Taken in the MOC's 'survey mode,' all four images were acquired at roughly 12 meters (39 ft) per pixel. Picture B zooms-in on the portion of the composite image that includes the 4 MOC images (the 100%-size view is 20 m (66 ft) per pixel). Other craters in the region near Spallanzani show features--at Viking Orbiter scale--that are reminiscent of the layering seen in Spallanzani. Exactly what these layers are made of and how they came to be where we see them today are mysteries, but it is possible that they are similar to the materials seen in the many craters and chasms of the equatorial latitudes on Mars.

  8. Continental Growth and the Sedimentary Record

    NASA Astrophysics Data System (ADS)

    Dhuime, B.; Hawkesworth, C. J.; Robinson, R. A. J.; Cawood, P. A.

    2014-12-01

    Detrital sedimentary rocks provide average samples of the continental crust formed at different times and in different places. Some materials are more susceptible to erosion and/or to preservation bias than others, and one issue is to understand how the compositions of a range of source rocks are then recorded in the sediments. Here we considered two different approaches to model the growth of the continental crust: (i) The variation of Nd isotopes in continental shales with different deposition ages, which requires a correction of the bias induced by preferential erosion of younger rocks through an erosion parameter usually referred to as 'K'. The determination of K, and the extent to which it varies in different erosion systems, thus have fundamental implications for the models of continental growth based on radiogenic isotopes in continental sediments. (ii) The variations in U-Pb, Hf and O isotopes in detrital zircons, from 'modern' sediments sampled worldwide. In this approach, O isotopes are used to screen 'hybrid' Hf model ages (i.e. ages resulting from mixing processes of crustal material from different ages) from Hf model ages that represent actual crust formation ages. These two approaches independently suggest that the continental crust has been generated continuously, but with a marked decrease in the continental growth rate at ~3 Ga. The >4 Ga to ~3 Ga period is characterised by relatively high net rates of continental growth (~3.0 km3.a-1), which are similar to the rates at which new crust is generated, and destroyed, at the present time. Net growth rates are much lower since 3 Ga (~0.8 km3.a-1), which may be attributed to higher rates of destruction of continental crust. The inflexion in the continental growth curve at ~3 Ga indicates a change in the way the crust was generated and preserved. This change may be linked to onset of subduction-driven plate tectonics and discrete subduction zones.

  9. Precambrian shield and basement tectonics in sedimentary basin analysis

    SciTech Connect

    Touborg, J.F.

    1984-04-01

    This study focused on the use of (1) regional structural analysis of basement and Precambrian rocks surrounding a sedimentary basin, and (2) tracing basement structures into the sedimentary basin. The structural analysis of the Precambrian shield has a fundamental bearing on interpretation of overlying sedimentary cover rocks. This is expressed in the southern part of the Hudson's Bay basin and its southeastern arm, the Moose River basin. For instance, the rims of both basins are controlled by faults or graben structures. Approximately 13 major fault systems with strike lengths of 200-300 km (125-186 mi) or more can be traced from the exposed Precambrian shield into the basin in terms of lineament arrays and/or aeromagnetic and/or gravity signature. The data suggest reactivation of faults during basin sedimentation. This type of basement structural analysis in areas adjacent to sedimentary basins can provide a valuable interpretation base for subsequent seismic surveys and basin evaluation.

  10. Alteration of Sedimentary Clasts in Martian Meteorite Northwest Africa 7034

    NASA Technical Reports Server (NTRS)

    McCubbin, F. M.; Tartese, R.; Santos, A. R.; Domokos, G.; Muttik, N.; Szabo, T.; Vazquez, J.; Boyce, J. W.; Keller, L. P.; Jerolmack, D. J.; Anand, M.; Moser, D. E.; Delhaye, T.; Shearer, C. K.; Agee, C. B.

    2014-01-01

    The martian meteorite Northwest Africa (NWA) 7034 and pairings represent the first brecciated hand sample available for study from the martian surface [1]. Detailed investigations of NWA 7034 have revealed substantial lithologic diversity among the clasts [2-3], making NWA 7034 a polymict breccia. NWA 7034 consists of igneous clasts, impact-melt clasts, and "sedimentary" clasts represented by prior generations of brecciated material. In the present study we conduct a detailed textural and geochemical analysis of the sedimentary clasts.

  11. Sedimentary Rocks of the Buckeye Range, Horlick Mountains, Antarctica.

    PubMed

    Long, W E

    1962-04-27

    In the Buckeye Range of the Horlick Mountains, 4000 feet of sedimentary rocks nonconformably overlie a granitic basement and underlie a thick diabasic sill. The sedimentary section consists of Devonian sandstone and shale (Horlick formation), Carboniferous (?) tillite (Buckeye formation), Permian (?) platy and carbonaceous shale (Discovery Ridge formation), and Permian arkose, shale, and numerous coal beds (Mount Glossopteris formation). This apparently is the first report of a Paleozoic tillite in Antarctica.

  12. Sedimentary Geology Context and Challenges for Cyberinfrastructure Data Management

    NASA Astrophysics Data System (ADS)

    Chan, M. A.; Budd, D. A.

    2014-12-01

    A cyberinfrastructure data management system for sedimentary geology is crucial to multiple facets of interdisciplinary Earth science research, as sedimentary systems form the deep-time framework for many geoscience communities. The breadth and depth of the sedimentary field spans research on the processes that form, shape and affect the Earth's sedimentary crust and distribute resources such as hydrocarbons, coal, and water. The sedimentary record is used by Earth scientists to explore questions such as the continental crust evolution, dynamics of Earth's past climates and oceans, evolution of the biosphere, and the human interface with Earth surface processes. Major challenges to a data management system for sedimentary geology are the volume and diversity of field, analytical, and experimental data, along with many types of physical objects. Objects include rock samples, biological specimens, cores, and photographs. Field data runs the gamut from discrete location and spatial orientation to vertical records of bed thickness, textures, color, sedimentary structures, and grain types. Ex situ information can include geochemistry, mineralogy, petrophysics, chronologic, and paleobiologic data. All data types cover multiple order-of-magnitude scales, often requiring correlation of the multiple scales with varying degrees of resolution. The stratigraphic framework needs dimensional context with locality, time, space, and depth relationships. A significant challenge is that physical objects represent discrete values at specific points, but measured stratigraphic sections are continuous. In many cases, field data is not easily quantified, and determining uncertainty can be difficult. Despite many possible hurdles, the sedimentary community is anxious to embrace geoinformatic resources that can provide better tools to integrate the many data types, create better search capabilities, and equip our communities to conduct high-impact science at unprecedented levels.

  13. Assiniboine Series.

    ERIC Educational Resources Information Center

    Allen, Minerva

    This series of illustrated booklets presents 13 Indian stories in a bilingual format of English and Assiniboine, an Indian tribal language. Written on the first grade level, the stories have the following titles: (1) "Orange Tree in Lodgepole"; (2) "Pretty Flower"; (3) Inktomi and the Rock"; (4) "Inktomi and the…

  14. Recording of climate and diagenesis through sedimentary DNA and fossil pigments at Laguna Potrok Aike, Argentina

    NASA Astrophysics Data System (ADS)

    Vuillemin, Aurèle; Ariztegui, Daniel; Leavitt, Peter R.; Bunting, Lynda; The Pasado Science Team

    2016-04-01

    Aquatic sediments record past climatic conditions while providing a wide range of ecological niches for microorganisms. In theory, benthic microbial community composition should depend on environmental features and geochemical conditions of surrounding sediments, as well as ontogeny of the subsurface environment as sediment degraded. In principle, DNA in sediments should be composed of ancient and extant microbial elements persisting at different degrees of preservation, although to date few studies have quantified the relative influence of each factor in regulating final composition of total sedimentary DNA assemblage. Here geomicrobiological and phylogenetic analyses of a Patagonian maar lake were used to indicate that the different sedimentary microbial assemblages derive from specific lacustrine regimes during defined climatic periods. Two climatic intervals (Mid-Holocene, 5 ka BP; Last Glacial Maximum, 25 ka BP) whose sediments harbored active microbial populations were sampled for a comparative environmental study based on fossil pigments and 16S rRNA gene sequences. The genetic assemblage recovered from the Holocene record revealed a microbial community displaying metabolic complementarities that allowed prolonged degradation of organic matter to methane. The series of Archaea identified throughout the Holocene record indicated an age-related stratification of these populations brought on by environmental selection during early diagenesis. These characteristics were associated with sediments resulting from endorheic lake conditions and stable pelagic regime, high evaporative stress and concomitant high algal productivity. In contrast, sulphate-reducing bacteria and lithotrophic Archaea were predominant in sediments dated from the Last Glacial Maximum, in which pelagic clays alternated with fine volcanic material characteristic of a lake level highstand and freshwater conditions, but reduced water column productivity. Comparison of sedimentary DNA composition

  15. NATURAL GAS RESOURCES IN DEEP SEDIMENTARY BASINS

    SciTech Connect

    Thaddeus S. Dyman; Troy Cook; Robert A. Crovelli; Allison A. Henry; Timothy C. Hester; Ronald C. Johnson; Michael D. Lewan; Vito F. Nuccio; James W. Schmoker; Dennis B. Riggin; Christopher J. Schenk

    2002-02-05

    From a geological perspective, deep natural gas resources are generally defined as resources occurring in reservoirs at or below 15,000 feet, whereas ultra-deep gas occurs below 25,000 feet. From an operational point of view, ''deep'' is often thought of in a relative sense based on the geologic and engineering knowledge of gas (and oil) resources in a particular area. Deep gas can be found in either conventionally-trapped or unconventional basin-center accumulations that are essentially large single fields having spatial dimensions often exceeding those of conventional fields. Exploration for deep conventional and unconventional basin-center natural gas resources deserves special attention because these resources are widespread and occur in diverse geologic environments. In 1995, the U.S. Geological Survey estimated that 939 TCF of technically recoverable natural gas remained to be discovered or was part of reserve appreciation from known fields in the onshore areas and State waters of the United. Of this USGS resource, nearly 114 trillion cubic feet (Tcf) of technically-recoverable gas remains to be discovered from deep sedimentary basins. Worldwide estimates of deep gas are also high. The U.S. Geological Survey World Petroleum Assessment 2000 Project recently estimated a world mean undiscovered conventional gas resource outside the U.S. of 844 Tcf below 4.5 km (about 15,000 feet). Less is known about the origins of deep gas than about the origins of gas at shallower depths because fewer wells have been drilled into the deeper portions of many basins. Some of the many factors contributing to the origin of deep gas include the thermal stability of methane, the role of water and non-hydrocarbon gases in natural gas generation, porosity loss with increasing thermal maturity, the kinetics of deep gas generation, thermal cracking of oil to gas, and source rock potential based on thermal maturity and kerogen type. Recent experimental simulations using laboratory

  16. paleofire: An R package to analyse sedimentary charcoal records from the Global Charcoal Database to reconstruct past biomass burning

    NASA Astrophysics Data System (ADS)

    Blarquez, Olivier; Vannière, Boris; Marlon, Jennifer R.; Daniau, Anne-Laure; Power, Mitchell J.; Brewer, Simon; Bartlein, Patrick J.

    2014-11-01

    We describe a new R package, paleofire, for analysis and synthesis of charcoal time series, such as those contained in the Global Charcoal Database (GCD), that are used to reconstruct paleofire activity (past biomass burning). paleofire is an initiative of the Global Paleofire Working Group core team (www.gpwg.org), whose aim is to encourage the use of sedimentary charcoal series to develop regional-to-global syntheses of paleofire activity, and to enhance access to the GCD data by providing a common research framework. Currently, paleofire features are organized into three different parts related to (i) site selection and charcoal series extraction from the GCD; (ii) charcoal data transformation; and (iii) charcoal series compositing and synthesis. We provide a technical description of paleofire and describe some new implementations such as the circular block bootstrap procedure. We tested the software using GCDv3 data from eastern North America, and provide examples of interpreting results of regional and global syntheses.

  17. Magmatic versus sedimentary volcanism: similarities of two different geological phenomena

    NASA Astrophysics Data System (ADS)

    Mazzini, Adriano

    2015-04-01

    Sedimentary volcanoes (or more commonly called mud volcanoes) are geological phenomena that are present in sedimentary basins of passive and active margins. At these localities gas and water related to hydrocarbon diagenetic and catagenetic production generate overpressure facilitating the rise of mobile and ductily deformable materials that breach through the denser overlying rocks. The results are surface powerful manifestations of mud eruptions that strikingly resemble to those of magmatic volcanoes. Magmatic and sedimentary volcanoes share many other similarities. Initially both systems are essentially gas driven and the subsurface plumbing systems are characterized by intrusions and a complex system of fractures and conduits that bifurcate from a central feeder channel that manifest in the surface as numerous satellite seeps and vents. In both cases are inferred secondary shallower chambers where reactions take place. Comparable structural morphologies (e.g. conical, elongated, pie-shaped, multicrater, swap-like, caldera collapse, subsiding flanks, plateau-like) and/or alteration of the original shape are in both cases related to e.g. density and viscosity of the erupted solids, to the gas content, to the frequency of the eruptions, and to the action of meteoric factors (e.g. strong erosion by rain, wind, temperature changes etc. etc.). Like for magmatic volcanoes, the periodicity of the eruptive activity is related to the time required to charge the system and create new overpressure, as well as how the structure seals during periods of dormancy. Earthquakes are documented to be a powerful trigger capable to activate faults (often hosting magmatic and sedimentary volcanoes) and/or facilitating the breaching of the upper layers, and allowing the rise of deeper charged fluids. Finally, both systems significantly contribute as active source for CH4 (sedimentary) and CO2 (magmatic) resulting of great importance for global budget estimates of sensitive gasses. The

  18. Folding and faulting of strain-hardening sedimentary rocks

    USGS Publications Warehouse

    Johnson, A.M.

    1980-01-01

    The question of whether single- or multi-layers of sedimentary rocks will fault or fold when subjected to layer-parallel shortening is investigated by means of the theory of elastic-plastic, strain-hardening materials, which should closely describe the properties of sedimentary rocks at high levels in the Earth's crust. The most attractive feature of the theory is that folding and faulting, intimately related in nature, are different responses of the same idealized material to different conditions. When single-layers of sedimentary rock behave much as strain-hardening materials they are unlikely to fold, rather they tend to fault, because contrasts in elasticity and strength properties of sedimentary rocks are low. Amplifications of folds in such materials are negligible whether contacts between layer and media are bonded or free to slip for single layers of dolomite, limestone, sandstone, or siltstone in media of shale. Multilayers of these same rocks fault rather than fold if contacts are bonded, but they fold readily if contacts between layers are frictionless, or have low yield strengths, for example due to high pore-water pressure. Faults may accompany the folds, occurring where compression is increased in cores of folds. Where there is predominant reverse faulting in sedimentary sequences, there probably were few structural units. ?? 1980.

  19. Chemical Composition of the Martian Surface: A Sedimentary Perspective

    NASA Astrophysics Data System (ADS)

    McLennan, Scott M.

    1999-01-01

    The sedimentary rock record is the primary repository of Earth history over the past four billion years. Major and trace element geochemistry and radiogenic isotopes are routinely used to investigate the sources of sediment (provenance) and the various processes that affect sediments throughout their history (e.g., weathering, sedimentary transport and recycling, diagenesis). The most sophisticated analytical methods that are available have been employed in sedimentary geochemistry and in many cases include grain by grain analyses of mineralogy, chemistry and isotopic characteristics. In turn, this information has been used to address many important issues, such as tectonic associations, environments of deposition, paleoclimates, paleohydrology, and crust/mantle evolution. Photographic, spectroscopic and geochemical results, returned from the surface of Mars over many years and many missions, have increasingly pointed towards a wide variety of sedimentary processes playing a dominant role in shaping the Martian surface. Accordingly, there is great potential for applying the knowledge that has been learned from studying terrestrial sedimentary rocks towards evaluating Martian geological history. Chemical and mineralogical analyses from the Martian surface, especially those from the Viking, Pathfinder, and Mars 2001/2003 missions, coupled with greater understanding of basaltic sedimentation on the Earth should provide the sedimentological framework within which to study the chemistry and mineralogy of returned Martian samples.

  20. Salinity constraints on subsurface archaeal diversity and methanogenesis in sedimentary rock rich in organic matter.

    PubMed

    Waldron, Patricia J; Petsch, Steven T; Martini, Anna M; Nüsslein, Klaus; Nüslein, Klaus

    2007-07-01

    The diversity of microorganisms active within sedimentary rocks provides important controls on the geochemistry of many subsurface environments. In particular, biodegradation of organic matter in sedimentary rocks contributes to the biogeochemical cycling of carbon and other elements and strongly impacts the recovery and quality of fossil fuel resources. In this study, archaeal diversity was investigated along a salinity gradient spanning 8 to 3,490 mM Cl(-) in a subsurface shale rich in CH(4) derived from biodegradation of sedimentary hydrocarbons. Shale pore waters collected from wells in the main CH(4)-producing zone lacked electron acceptors such as O(2), NO(3)(-), Fe(3+), or SO(4)(2-). Acetate was detected only in high-salinity waters, suggesting that acetoclastic methanogenesis is inhibited at Cl(-) concentrations above approximately 1,000 mM. Most-probable-number series revealed differences in methanogen substrate utilization (acetate, trimethylamine, or H(2)/CO(2)) associated with chlorinity. The greatest methane production in enrichment cultures was observed for incubations with salinity at or close to the native pore water salinity of the inoculum. Restriction fragment length polymorphism analyses of archaeal 16S rRNA genes from seven wells indicated that there were links between archaeal communities and pore water salinity. Archaeal clone libraries constructed from sequences from 16S rRNA genes isolated from two wells revealed phylotypes similar to a halophilic methylotrophic Methanohalophilus species and a hydrogenotrophic Methanoplanus species at high salinity and a single phylotype closely related to Methanocorpusculum bavaricum at low salinity. These results show that several distinct communities of methanogens persist in this subsurface, CH(4)-producing environment and that each community is adapted to particular conditions of salinity and preferential substrate use and each community induces distinct geochemical signatures in shale formation waters.

  1. Salinity Constraints on Subsurface Archaeal Diversity and Methanogenesis in Sedimentary Rock Rich in Organic Matter▿

    PubMed Central

    Waldron, Patricia J.; Petsch, Steven T.; Martini, Anna M.; Nüslein, Klaus

    2007-01-01

    The diversity of microorganisms active within sedimentary rocks provides important controls on the geochemistry of many subsurface environments. In particular, biodegradation of organic matter in sedimentary rocks contributes to the biogeochemical cycling of carbon and other elements and strongly impacts the recovery and quality of fossil fuel resources. In this study, archaeal diversity was investigated along a salinity gradient spanning 8 to 3,490 mM Cl− in a subsurface shale rich in CH4 derived from biodegradation of sedimentary hydrocarbons. Shale pore waters collected from wells in the main CH4-producing zone lacked electron acceptors such as O2, NO3−, Fe3+, or SO42−. Acetate was detected only in high-salinity waters, suggesting that acetoclastic methanogenesis is inhibited at Cl− concentrations above ∼1,000 mM. Most-probable-number series revealed differences in methanogen substrate utilization (acetate, trimethylamine, or H2/CO2) associated with chlorinity. The greatest methane production in enrichment cultures was observed for incubations with salinity at or close to the native pore water salinity of the inoculum. Restriction fragment length polymorphism analyses of archaeal 16S rRNA genes from seven wells indicated that there were links between archaeal communities and pore water salinity. Archaeal clone libraries constructed from sequences from 16S rRNA genes isolated from two wells revealed phylotypes similar to a halophilic methylotrophic Methanohalophilus species and a hydrogenotrophic Methanoplanus species at high salinity and a single phylotype closely related to Methanocorpusculum bavaricum at low salinity. These results show that several distinct communities of methanogens persist in this subsurface, CH4-producing environment and that each community is adapted to particular conditions of salinity and preferential substrate use and each community induces distinct geochemical signatures in shale formation waters. PMID:17468287

  2. Eolian Dust and the Origin of Sedimentary Chert

    USGS Publications Warehouse

    Cecil, C. Blaine

    2004-01-01

    This paper proposes an alternative model for the primary source of silica contained in bedded sedimentary chert. The proposed model is derived from three principal observations as follows: (1) eolian processes in warm-arid climates produce copious amounts of highly reactive fine-grained quartz particles (dust), (2) eolian processes in warm-arid climates export enormous quantities of quartzose dust to marine environments, and (3) bedded sedimentary cherts generally occur in marine strata that were deposited in warm-arid paleoclimates where dust was a potential source of silica. An empirical integration of these observations suggests that eolian dust best explains both the primary and predominant source of silica for most bedded sedimentary cherts.

  3. Carbonate concretions: an ideal sedimentary host for microfossils.

    USGS Publications Warehouse

    Blome, C.D.; Albert, N.R.

    1985-01-01

    Enhanced preservation correlates with early diagenetic concretion formation at or near the sediment-water interface and with higher carbonate, organic material, and metallic cation content than in surrounding rocks. Early diagenetic growth is inferred by diverging sedimentary laminations and small-scale sedimentary structures in fossiliferous carbonate concretions. High initial concentration of microorganisms or fecal pellets may commonly be responsible for incipient carbonate-concretion growth. Excellent preservation is demonstrated by radiolarians and palynomorphs extracted from a carbonate concretion from the Middle Jurassic Shelikof Formation, S Alaska.-from Authors

  4. Excess europium content in Precambrian sedimentary rocks and continental evolution

    NASA Technical Reports Server (NTRS)

    Jakes, P.; Taylor, S. R.

    1974-01-01

    It is proposed that the europium excess in Precambrian sedimentary rocks, relative to those of younger age, is derived from volcanic rocks of ancient island arcs, which were the source materials for the sediments. Precambrian sedimentary rocks and present-day volcanic rocks of island arcs have similar REE patterns, total REE abundances, and excess Eu, relative to the North American shale composite. The present upper crustal REE pattern, as exemplified by that of sediments, is depleted in Eu, relative to chondrites. This depletion is considered to be a consequence of development of a granodioritic upper crust by partial melting in the lower crust, which selectively retains europium.

  5. Building a Bridge to Deep Time: Sedimentary Systems Across Timescales

    NASA Astrophysics Data System (ADS)

    Romans, B.; Castelltort, S.; Covault, J. A.; Walsh, J. P.

    2013-12-01

    It is increasingly important to understand the complex and interdependent processes associated with sediment production, transport, and deposition at timescales relevant to civilization (annual to millennial). However, predicting the response of sedimentary systems to global environmental change across a range of timescales remains a significant challenge. For example, a significant increase in global average temperature at the Paleocene-Eocene boundary (55.8 Ma) is interpreted to have occurred over millennial timescales; however, the specific response of sedimentary systems (e.g., timing and magnitude of sediment flux variability in river systems) to that forcing is debated. Thus, using such environmental perturbations recorded in sedimentary archives as analogs for ongoing/future global change requires improved approaches to bridging across time. Additionally, the ability to bridge timescales is critical for addressing other questions about sedimentary system behavior, including signal propagation and signal versus ';noise' in the record. The geologic record provides information that can be used to develop a comprehensive understanding of process-response behavior at multiple timescales. The geomorphic ';snapshot' of present-day erosional and depositional landscapes can be examined to reconstruct the history of processes that created the observable configurations. Direct measurement and monitoring of active processes are used to constrain conceptual and numerical models and develop sedimentary system theory. But real-time observations of active Earth-surface processes are limited to the very recent, and how such processes integrate over longer timescales to transform into strata remains unknown. At longer timescales (>106 yr), the stratigraphic record is the only vestige of ancient sedimentary systems. Stratigraphic successions contain a complex record of sediment deposition and preservation, as well as the detrital material that originated in long since denuded

  6. High resolution model studies of transport of sedimentary material in the south-western Baltic

    NASA Astrophysics Data System (ADS)

    Seifert, Torsten; Fennel, Wolfgang; Kuhrts, Christiane

    2009-02-01

    The paper presents high resolution model simulations of transport, deposition and resuspension of sedimentary material in the south-western Baltic, based on an upgrade of the sediment transport model described in the work of Kuhrts et al. [Kuhrts, C., Fennel, W., Seifert, T., 2004. Model studies of transport of sedimentary material in the Western Baltic. Journal of Marine Systems 52, 167.]. In the western Baltic, a grid spacing of at least 1 nautical mile is required to resolve the shallow and narrow bathymetry and the associated current patterns. A series of experimental model simulations is carried out with forcing data for the year 1993, which include a sequence of storms in January. Compared to earlier model versions, a more detailed description of potential deposition areas can be provided. The study quantifies the influence of enhanced bottom roughness caused by biological structures, like mussels and worm holes, provides estimates of the regional erosion risks for fine grained sediments, and analyses scenarios of the settling and spreading of material at dumping sites. Although the effects of changed bottom roughness, as derived from more detailed, re-classified sea floor data, are relatively small, the sediment transport and deposition patterns are clearly affected by the variation of the sea bed properties.

  7. Recurrent giant earthquakes in South-Central Chile revealed by lacustrine sedimentary records

    NASA Astrophysics Data System (ADS)

    Moernaut, J.; de Batist, M. A.; Heirman, K.; van Daele, M.; Brümmer, R.; Pino, M.; Urrutia, R.; Wolff, C.; Brauer, A.; Roberts, S.; Kilian, R.

    2009-12-01

    Megathrust (‘giant’) earthquakes in the South-Central Chilean subduction zone (e.g. 1960 earthquake; Mw: 9.5) cause landslides, tsunamis, soil liquefaction, coastal uplift/subsidence, volcanic eruptions, all of which pose a major threat to society. A reliable seismic hazard assessment requires establishing if such mega-events occurred in the past and determining their recurrence pattern. The Lake District (39-42°S) in South-Central Chile, located in the northern half of the 1960 earthquake rupture zone, contains several large, steep-sloped glacigenic lakes with high sedimentation rates, and whose sedimentary deposits are highly susceptible to earthquake-triggered slope instability. To establish the reoccurrence interval of earthquakes during the Late Holocene, we mapped the spatial distribution of seismically-induced sedimentary ‘event’ deposits and structures in each lake using very-high resolution seismic data, and collected a series of short gravity cores and long piston cores. Multi-proxy sedimentary analyses (color, magnetic susceptibility, density, geochemistry, grain size), radiocarbon dating, varve-counting, and tephro-stratigraphy were used to identify ‘event’ deposits in each core and correlate paleoseismic horizons across basins. The sediment sequences investigated contain four main types of earthquake-induced structures: 1) multiple mass-wasting deposits on a single stratigraphic level, which are relicts of a basin-wide, subaqueous slope instability ‘event’; 2) homogenite deposits in the deepest parts of steep basins indicative of lake seiches and tsunamis; 3) fluid-escape structures (e.g. sediment volcanoes), which reflect sudden liquefaction in buried mass-wasting deposits and subsequent vertical fluidization flow; 4) in-situ deformed units (e.g., contorted bedding) in nearly-flat layers, which reflect strong horizontal ground acceleration events. Comparison with historical earthquakes suggests the spatial extent, thickness, nature of

  8. Chlorine Isotope Compositions of Sedimentary Rocks Are Preserved During Prograde Alpine Metamorphism

    NASA Astrophysics Data System (ADS)

    Selverstone, J.; Sharp, Z. D.

    2013-12-01

    Chlorine stable isotope compositions of two Swiss sedimentary sequences and their metamorphic equivalents were measured in order to study fractionation effects of prograde metamorphism and devolatilization. Protoliths (n=25) were collected from a 50 m section of Triassic deltaic and lagoonal strata and Liassic marine black shales in a well-characterized quarry. Borehole samples through the same sequence (n=12) were acquired from the collection of M. Frey. Low greenschist to middle amphibolite facies equivalents (n>80) were collected from the Glarner Alps, Urseren Zone, and Lukmanier region. δ37Cl values of silicate-bound chloride (SBC) are constant within individual sedimentary layers, but vary from -2.0 to +2.5‰ throughout the Triassic sequence and from -3.0 to 0‰ in the black shales. All dolomitic and gypsiferous samples have positive δ37Cl values. Colored marls and shales from the base of the Triassic sequence are isotopically negative, whereas those from the top are isotopically positive; in each case, however, δ37Cl values are elevated in the most oxidized layers. Water-soluble δ37Cl values are 0.5-3.0‰ lower than SBC values in Triassic samples, but are 0.4-2.4‰ higher than SBC in black shales. Cl- contents range from 5-100 ppm in SBC fractions in both protolith series, and from 5-70 ppm in WSC fractions. Metamorphic equivalents of the Triassic and Liassic protoliths record the same overall ranges in δ37Cl as their protoliths. Samples with similar bulk composition but different metamorphic grades differ in δ37Cl by ≤1‰. More oxidized metamorphic samples record higher δ37Cl than reduced samples from the same localities, consistent with data from the protoliths. These data lead to the following conclusions: (1) Both continental and marine sedimentary rocks display large heterogeneities in δ37Cl. (2) Negative Δ37Cl (SBC-WSC) fractionation in black shales may reflect partitioning between soluble and insoluble organohalogen compounds, in

  9. A Sedimentary Rock Classification Scheme for Introductory Geology.

    ERIC Educational Resources Information Center

    Davis, Larry Eugene; Eves, Robert Leo

    1986-01-01

    Presents a classification scheme for identifying sedimentary rocks in introductory geology laboratories. The key consists of an ordered sequence of tests to perform and observations to make which then suggests a rock name or directs the student to additional tests and/or observations. (ML)

  10. Sedimentary Geochemistry of Martian Samples from the Pathfinder Mission

    NASA Technical Reports Server (NTRS)

    McLennan, Scott M.

    2001-01-01

    The purpose of this research project was to evaluate the APXS data collected on soils and rocks at the Pathfinder site in terms of sedimentary geochemistry. Below are described the major findings of this research: (1) An influential model to explain the chemical variation among Pathfinder soils and rocks is a two component mixing model where rocks of fairly uniform composition mix with soil of uniform composition; (2) The very strong positive correlation between MgO and SO, points to a control by a MgSO4 mineral however, spectroscopic data continue to suggest that Fe-sulfates, notably schwertmannite and jarosite, may be important components; (3) In an attempt to better understand the causes of complexities in mixing relationships, the possible influence of sedimentary transport has been evaluated; (4) Another aspect of this research has been to examine the possibility of sedimentary silica being a significant phase on Mars; and (5) On Earth, the geochemistry of sedimentary rocks has been used to constrain the chemical composition of the continental crust and an important part of this research was to evaluate this approach for Mars.

  11. Sedimentary exhalative (sedex) zinc-lead-silver deposit model

    USGS Publications Warehouse

    Emsbo, Poul; Seal, Robert R.; Breit, George N.; Diehl, Sharon F.; Shah, Anjana K.

    2016-10-28

    This report draws on previous syntheses and basic research studies of sedimentary exhalative (sedex) deposits to arrive at the defining criteria, both descriptive and genetic, for sedex-type deposits. Studies of the tectonic, sedimentary, and fluid evolution of modern and ancient sedimentary basins have also been used to select defining criteria. The focus here is on the geologic characteristics of sedex deposit-hosting basins that contain greater than 10 million metric tons of zinc and lead. The enormous size of sedex deposits strongly suggests that basin-scale geologic processes are involved in their formation. It follows that mass balance constraints of basinal processes can provide a conceptual underpinning for the evaluation of potential ore-forming mechanisms and the identification of geologic indicators for ore potential in specific sedimentary basins. Empirical data and a genetic understanding of the physicochemical, geologic, and mass balance conditions required for each of these elements are used to establish a hierarchy of quantifiable geologic criteria that can be used in U.S. Geological Survey national assessments.  In addition, this report also provides a comprehensive evaluation of environmental considerations associated with the mining of sedex deposits.

  12. Using Aluminum Foil to Record Structures in Sedimentary Rock.

    ERIC Educational Resources Information Center

    Metz, Robert

    1982-01-01

    Aluminum foil can be used to make impressions of structures preserved in sedimentary rock. The impressions can be projected onto a screen, photographed, or a Plaster of Paris model can be made from them. Impressions of ripple marks, mudcracks, and raindrop impressions are provided in photographs illustrating the technique. (Author/JN)

  13. Riverine Carbon and the Sedimentary Record on the Continental Shelves

    DTIC Science & Technology

    2004-09-30

    Riverine Carbon and the Sedimentary Record on the Continental Shelves Stefano Miserocchi Istituto Scienze Marine, Sezione Geologia Marina...formerly Istituto di Geologia Marina) Consiglio Nazionale delle Ricerche Via Gobetti, 101 40129 Bologna, Italy phone: +39 (051) 6398880 Fax. +39 (051... Geologia Marina,,(formerly Istituto di Geologia Marina),Consiglio Nazionale delle Ricerche,,Via Gobetti, 101,40129 Bologna, Italy, , 8. PERFORMING

  14. CUTS FOR MTR EXCAVATION ILLUSTRATE SEDIMENTARY MANTLE OF SOIL AND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    CUTS FOR MTR EXCAVATION ILLUSTRATE SEDIMENTARY MANTLE OF SOIL AND GRAVEL OVERLAYING LAVA ROCK FIFTY FEET BELOW. SAGEBRUSH HAS BEEN SCOURED FROM REST OF SITE. CAMERA PROBABLY FACES SOUTHWEST. INL NEGATIVE NO. 67. Unknown Photographer, 6/4/1950 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

  15. Geofluid Dynamics of Faulted Sedimentary Basins

    NASA Astrophysics Data System (ADS)

    Garven, G.; Jung, B.; Boles, J. R.

    2014-12-01

    Faults are known to affect basin-scale groundwater flow, and exert a profound control on petroleum migration/accumulation, the PVT-history of hydrothermal fluids, and the natural (submarine) seepage from offshore reservoirs. For example, in the Santa Barbara basin, measured gas flow data from a natural submarine seep area in the Santa Barbara Channel helps constrain fault permeability k ~ 30 millidarcys for the large-scale upward migration of methane-bearing formation fluids along one of the major fault zones. At another offshore site near Platform Holly, pressure-transducer time-series data from a 1.5 km deep exploration well in the South Ellwood Field demonstrate a strong ocean tidal component, due to vertical fault connectivity to the seafloor. Analytical solutions to the poroelastic flow equation can be used to extract both fault permeability and compressibility parameters, based on tidal-signal amplitude attenuation and phase shift at depth. These data have proven useful in constraining coupled hydrogeologic 2-D models for reactive flow and geomechanical deformation. In a similar vein, our studies of faults in the Los Angeles basin, suggest an important role for the natural retention of fluids along the Newport-Inglewood fault zone. Based on the estimates of fault permeability derived above, we have also constructed new two-dimensional numerical simulations to characterize large-scale multiphase flow in complex heterogeneous and anisotropic geologic profiles, such as the Los Angeles basin. The numerical model was developed in our lab at Tufts from scratch, and based on an IMPES-type algorithm for a finite element/volume mesh. This numerical approach allowed us model large differentials in fluid saturation and relative permeability, caused by complex geological heterogeneities associated with sedimentation and faulting. Our two-phase flow models also replicated the formation-scale patterns of petroleum accumulation associated with the basin margin, where deep

  16. Sedimentary settings of marine middle mesozoic allochthonous complexes of northeastern asia and their correlation

    NASA Astrophysics Data System (ADS)

    Vishnevskaya, V. S.; Filatova, N. I.

    2017-01-01

    The correlation of the Jurassic-Lower Cretaceous cherty-volcanic complexes constituting nappe scales of the tectonostratigraphic sections of the Okhotsk-Koryak orogenic belt served as a basis for interpreting the lateral and vertical series of Norian-Barremian marine sedimentary settings in the North Pacific. The correlation was based on radiolarian and geodynamic analyses. The taxonomic compositions of radiolarian assemblage were used as proxies for reconstructing oceanic and marginal marine settings and the seafloor topography (deep and shallow neritic regions, elevated areas (atolls, guyot, and island arcs), facilitating the upwelling). The stage-by-stage reconstruction of the paleoenvironments became possible owing to the stage subdivision of previously almost entirely barren allochthonous formations.

  17. Parametric Analysis of the Factors Controlling the Costs of Sedimentary Geothermal Systems - Preliminary Results (Poster)

    SciTech Connect

    Augustine, C.

    2013-10-01

    Parametric analysis of the factors controlling the costs of sedimentary geothermal systems was carried out using a modified version of the Geothermal Electricity Technology Evaluation Model (GETEM). The sedimentary system modeled assumed production from and injection into a single sedimentary formation.

  18. Sedimentary responses to sub-aerial felsic volcanism from the Late Devonian-Early Carboniferous northern Macalister Synclinorium, southeastern Australia

    NASA Astrophysics Data System (ADS)

    O'Halloran, G. J.; Gaul, A. J.

    1997-04-01

    Active sub-aerial volcanism has the capability to rapidly alter both the topographic and drainage characteristics of a landscape, and thus fundamentally influence resulting sedimentary facies. Relationships between sedimentation and volcanism are explored in this paper, via an investigation of the stratigraphy and early depositional history of the Upper Devonian volcano-sedimentary units of the northern Macalister Synclinorium, east-central Victoria. Complex interfingering relationships exist between sub-aerial felsic volcanic successions (Rose River Volcanics) and alluvial, fluvial and lacustrine sedimentary units (the Bindaree and Howitt Spur Formations). A depositional model is presented for these units, in which the Rose River Volcanics, an outflow (ignimbritic plateau) facies of the Tolmie caldera complex to the north, co-existed with a series of volcaniclastic alluvial fans and freshwater lakes. A dacitic volcanic centre (Refrigerator Gap Dacite) appears to have developed somewhat separately to the south, in the Jamieson River area. These lower successions of the northern Macalister Synclinorium record an episode of sedimentation in close proximity to an active felsic volcanic terrain, and in a landscape of significant topographic relief. The conglomerates of the Bindaree Formation, in particular, record the supply of abundant felsic volcanic detritus via high-gradient proximal alluvial stream systems. Comparisons can be made with sedimentological processes operating during deposition of overlying sedimentary successions, where influences by primary volcanic activity were less important. Well defined channel geometry successions and a diversification in clast and grain types within these younger units indicate ongoing headward erosion into metasedimentary basement rocks, and deposition within lower-gradient, higher-order stream systems.

  19. Heavy-mineral analysis of sedimentary rocks of northern Alaska

    USGS Publications Warehouse

    Morris, Robert Hamilton

    1952-01-01

    The Navy Oil Unit of the United States Geological Survey has been investigating the geology of Naval Petroleum Reserve No. 4, northern Alaska. As part of this program, heavy-mineral samples were prepared from cores of the test wells and core holes and studied to determine stratigraphic correlations. Using the following criteria: (1) presence of diagnostic minerals or mineral suites; (2) relative abundance of specific minerals; (3) degree of rounding of mineral grains; (4) distinction as to grain form; eight heavy-mineral zones have been recognized in Triassic, Jurassic, Cretaceous, and Quaternary sedimentary rocks. Correlations based on these zones are shown. Source areas and rocks are discussed in relation to geologic history and genesis of the Mesozoic and Quaternary sedimentary rocks.

  20. Buried Proterozoic foredeep under the Western Canada Sedimentary Basin?

    NASA Astrophysics Data System (ADS)

    Boerner, D. E.; Kurtz, R. D.; Craven, J. A.; Rondenay, S.; Qian, W.

    1995-04-01

    Electromagnetic studies of the Precambrian basement beneath the Western Canada Sedimentary Basin in Alberta indicate a narrow linear conductivity anomaly spatially correlated with a strong positive magnetic feature, the Red Deer high. The conductor is located below sedimentary cover near the top of the crystalline basement and has limited depth extent. We propose that this anomalous feature represents graphitic metasedimentary rocks in the euxinic-flysch facies of a Proterozoic foredeep sequence. The strong magnetic anomaly results from an associated iron formation deposited on the outer ramp of the foredeep. This model explains the geophysical anomalies, has analogues on the exposed shield, and is consistent with the timing, deformation history, and known geology of the Precambrian basement.

  1. Isotope studies of dolomite formation under sedimentary conditions

    USGS Publications Warehouse

    Clayton, R.N.; Jones, B.F.

    1968-01-01

    Measurements of stable isotope abundances of the carbonate portion of the sediment in Deep Springs Lake, California, indicate the presence of at least three phases: a magnesian calcite, a primary sedimentary dolomite, and a detrital dolomite. The former two have isotopic compositions consistent with precipitation at isotopic equilibrium from waters of the lake area. The measured isotopic fractionation factor between sedimentary dolomite and its interstitial water is 1.0351, which is outside the range possible for calcite-water. This indicates that the dolomite has formed by direct crystallization from solution and not from a caloite precursor without further isotope exchange. Isotopic and X-ray evidence does not support the contention of Peterson et al. (1966) that Deep Springs Lake dolomite crystals grow by means of a calcite-like surface layer. ?? 1968.

  2. Organic sedimentary deposits in Titan's dry lakebeds: Probable evaporite

    USGS Publications Warehouse

    Barnes, J.W.; Bow, J.; Schwartz, J.; Brown, R.H.; Soderblom, J.M.; Hayes, A.G.; Vixie, G.; Le, Mouelic S.; Rodriguez, S.; Sotin, C.; Jaumann, R.; Stephan, K.; Soderblom, L.A.; Clark, R.N.; Buratti, B.J.; Baines, K.H.; Nicholson, P.D.

    2011-01-01

    We report the discovery of organic sedimentary deposits at the bottom of dry lakebeds near Titan's north pole in observations from the Cassini Visual and Infrared Mapping Spectrometer (VIMS). We show evidence that the deposits are evaporitic, making Titan just the third known planetary body with evaporitic processes after Earth and Mars, and is the first that uses a solvent other than water. ?? 2011 Elsevier Inc.

  3. Jurassic sedimentary basins in the Central Asian orogenic belt

    SciTech Connect

    Bebeshev, I.I.

    1995-05-01

    The principal stages of development of Jurassic sedimentary basins (from their origin to the end of their existence) in the Central Asian orogenic belt are considered. The interrelations of the basins with the surrounding paleorises are investigated. Paleogeographic maps are compiled representing the evolution of paleolandscapes and revealing their interrelations in space and time for each stage. Areas with the highest prospects for coal are found.

  4. Sources of sedimentary humic substances: vascular plant debris

    NASA Astrophysics Data System (ADS)

    Ertel, John R.; Hedges, John I.

    1985-10-01

    A modern Washington continental shelf sediment was fractionated densimetrically using either an organic solvent, CBrCl 3, or aqueous ZnCl 2. The resulting low density materials (<2.06 g/ml) account for only 1% of the sediment mass but contain 25% of the sedimentary organic carbon and 53% of the lignin. The C/N ratios (30-40) and lignin phenol yields ( Λ = 8) and compositions indicate that the low density materials are essentially pure vascular plant debris which is slightly enriched in woody ( versus nonwoody) tissues compared to the bulk sediment. The low density materials yield approximately one-third of their organic carbon as humic substances and contribute 23% and 14% of the total sedimentary humic and fulvic acids, respectively. Assuming that the lignin remaining in the sedimentary fraction is also contained in plant fragments that yield similar levels of humic substances, then 50% and 30% of the total humic and fulvic acids, respectively, arise directly from plant debris. Base-extraction of fresh and naturally degraded vascular plant materials reveals that significant levels of humic and fulvic acids are obtained using classical extraction techniques. Approximately 1-2% of the carbon from fresh woods and 10-25% from leaves and bark were isolated as humic acids and 2-4 times those levels as fulvic acids. A highly degraded hardwood yielded up to 44% of its carbon as humic and fulvic acids. The humic acids from fresh plants are generally enriched in lignin components relative to carbohydrates and recognizable biochemicals account for up to 50% of the total carbon. Humic and fulvic acids extracted directly from sedimentary plant debris could be responsible for a major fraction of the biochemical component of humic substances.

  5. Preliminary catalog of the sedimentary basins of the United States

    USGS Publications Warehouse

    Coleman, James L.; Cahan, Steven M.

    2012-01-01

    One hundred forty-four sedimentary basins (or groups of basins) in the United States (both onshore and offshore) are identified, located, and briefly described as part of a Geographic Information System (GIS) data base in support of the Geologic Carbon Dioxide Sequestration National Assessment Project (Brennan and others, 2010). This catalog of basins is designed to provide a check list and basic geologic framework for compiling more detailed geologic and reservoir engineering data for this project and other future investigations.

  6. Analysis of the Behavior of Sedimentary Rocks Under Impact Loading

    NASA Astrophysics Data System (ADS)

    Millon, Oliver; Ruiz-Ripoll, Maria Luisa; Hoerth, Tobias

    2016-11-01

    In multiple engineering fields such as rock drilling or building constructions or extreme events like earthquakes or impacts, the dynamic properties of rock play an important role. A way to model these events and define measures to minimize the damage derived from these events is created by means of numerical analysis. Hence, the knowledge of the dynamic material behavior is essential for studying the effects of such a loading scenario. Solid geological materials, from the family of the sedimentary rocks, have been analyzed under quasi-static loads. However, there is a lack of knowledge when high strain rate loadings are involved. Within this context, the paper focuses on the experimental characterization of two sedimentary rocks, sandstone and limestone, under impact loading using the Hopkinson-Bar spallation and compression tests. The analysis encompasses the determination of the tensile and compressive properties as well as the comparison between the quasi-static and dynamic behavior (dynamic increase factors). The paper fills the gap of information existing about dynamic behavior of sedimentary rocks under strain rates between 100 and 5.2 × 102 s-1. Furthermore, the fragmentation under different strain rates is investigated and conclusions with respect to energy absorption capacity are drawn.

  7. DOE workshop: Sedimentary systems, aqueous and organic geochemistry

    SciTech Connect

    Not Available

    1993-07-01

    A DOE workshop on sedimentary systems, aqueous and organic geochemistry was held July 15-16, 1993 at Lawrence Berkeley Laboratory. Papers were organized into several sections: Fundamental Properties, containing papers on the thermodynamics of brines, minerals and aqueous electrolyte solutions; Geochemical Transport, covering 3-D imaging of drill core samples, hydrothermal geochemistry, chemical interactions in hydrocarbon reservoirs, fluid flow model application, among others; Rock-Water Interactions, with presentations on stable isotope systematics of fluid/rock interaction, fluid flow and petotectonic evolution, grain boundary transport, sulfur incorporation, tracers in geologic reservoirs, geothermal controls on oil-reservoir evolution, and mineral hydrolysis kinetics; Organic Geochemistry covered new methods for constraining time of hydrocarbon migration, kinetic models of petroleum formation, mudstones in burial diagenesis, compound-specific carbon isotope analysis of petroleums, stability of natural gas, sulfur in sedimentary organic matter, organic geochemistry of deep ocean sediments, direct speciation of metal by optical spectroscopies; and lastly, Sedimentary Systems, covering sequence stratigraphy, seismic reflectors and diagenetic changes in carbonates, geochemistry and origin of regional dolomites, and evidence of large comet or asteroid impacts at extinction boundaries.

  8. Decoupled sedimentary records of combustion: Causes and implications

    NASA Astrophysics Data System (ADS)

    Hanke, Ulrich M.; Eglinton, Timothy I.; Braun, Ana L. L.; Reddy, Christopher M.; Wiedemeier, Daniel B.; Schmidt, Michael W. I.

    2016-05-01

    Pyrogenic carbon (PyC) is a collective term for carbon-rich residues comprised of a continuum of products arising from biomass burning and fossil-fuel combustion. PyC is ubiquitous in the environment where it can be transported by wind and water before being deposited in aquatic sediments. We compare results from four different methods used to trace PyC that were applied to a high-temporal resolution sedimentary record in order to constrain changes in PyC concentrations and fluxes over the past ~250 years. We find markedly discordant records for different PyC tracers, particularly during the preindustrial age, implying different origins and modes of supply of sedimentary PyC. In addition to providing new insights into the composition of sedimentary combustion products, this study reveals that elucidation of past combustion processes and development of accurate budgets of PyC production and deposition on local to regional scales requires careful consideration of both source characteristics and transport processes.

  9. Physical processes affecting the sedimentary environments of Long Island Sound

    USGS Publications Warehouse

    Signell, R.P.; Knebel, H. J.; List, J.H.; Farris, A.S.; ,

    1997-01-01

    A modeling study was undertaken to simulate the bottom tidal-, wave-, and wind-driven currents in Long Island Sound in order to provide a general physical oceanographic framework for understanding the characteristics and distribution of seafloor sedimentary environments. Tidal currents are important in the funnel-shaped eastern part of the Sound, where a strong gradient of tidal-current speed was found. This current gradient parallels the general westward progression of sedimentary environments from erosion or non-deposition, through bedload transport and sediment sorting, to fine-grained deposition. Wave-driven currents, meanwhile, appear to be important along the shallow margins of the basin, explaining the occurrence of relatively coarse sediments in regions where tidal currents alone are not strong enough to move sediment. Finally, westerly wind events are shown to locally enhance bottom currents along the axial depression of the sound, providing a possible explanation for the relatively coarse sediments found in the depression despite tide- and wave-induced currents below the threshold of sediment movement. The strong correlation between the near-bottom current intensity based on the model results and the sediment response as indicated by the distribution of sedimentary environments provides a framework for predicting the long-term effects of anthropogenic activities.

  10. Sedimentary sequence evolution in a Foredeep basin: Eastern Venezuela

    SciTech Connect

    Bejarano, C.; Funes, D.; Sarzalho, S.; Audemard, F.; Flores, G.

    1996-08-01

    Well log-seismic sequence stratigraphy analysis in the Eastern Venezuela Foreland Basin leads to study of the evolution of sedimentary sequences onto the Cretaceous-Paleocene passive margin. This basin comprises two different foredeep sub-basins: The Guarico subbasin to the west, older, and the Maturin sub-basin to the east, younger. A foredeep switching between these two sub-basins is observed at 12.5 m.y. Seismic interpretation and well log sections across the study area show sedimentary sequences with transgressive sands and coastal onlaps to the east-southeast for the Guarico sub-basin, as well as truncations below the switching sequence (12.5 m.y.), and the Maturin sub-basin shows apparent coastal onlaps to the west-northwest, as well as a marine onlap (deeper water) in the west, where it starts to establish. Sequence stratigraphy analysis of these sequences with well logs allowed the study of the evolution of stratigraphic section from Paleocene to middle Miocene (68.0-12.0 m.y.). On the basis of well log patterns, the sequences were divided in regressive-transgressive-regressive sedimentary cycles caused by changes in relative sea level. Facies distributions were analyzed and the sequences were divided into simple sequences or sub- sequences of a greater frequencies than third order depositional sequences.

  11. Compound-specific nitrogen isotopes of equatorial Pacific sedimentary record

    NASA Astrophysics Data System (ADS)

    Sauthoff, W.; Ravelo, A. C.; Mccarthy, M. D.

    2014-12-01

    Compound specific nitrogen isotopic analysis of amino acids (δ15N-AA) is a technique that is widely used in regional ecology and food web studies, with newly expanding applications in organic geochemistry. However, its applicability to marine sediment has been minimally examined. This study is one of the first δ15N-AA applications into the paleorecord of marine sediment. We explore how δ15N-AA measurements provide insights into past changes in water column N cycling and N utilization, and into post-depositional processes that impact sedimentary N. This is possible because δ15N-AA investigates the molecular-level basis of the bulk sedimentary δ15N signal, revealing possible diagenetic alteration of sedimentary organic matter. Our goal was is to investigate the extent of alteration (vs. preservation) of individual sedimentary amino acid δ15N values from surface nitrate δ15N across a wide range of depositional environments. The δ15N of bulk sediment differs from that of the surface nitrate δ15N signal because of water column processes or more often because of alteration of the signal during initial sedimentation. To investigate this alteration we compare δ15N-AA to bulk δ15N measurements in a suite of equatorial Pacific core tops (378-4360 m below sea level) across contrasting oceanographic and sedimentary depositional conditions (e.g. high vs. low productivity, hypoxic vs. oxic bottom waters). To examine down core diagenetic alteration of the sediment record, we present δ15N-AA and bulk δ15N of selected deeper depths to observe 1) if diagenetic shift is coherently resolved by both types of measurements and 2) if select individual δ15N-AA values remain representative of the surface organic δ15N signal. We hypothesize that compound specific analysis (δ15N-AA) will provide a molecular level assessment of mechanism for diagenetic changes in bulk organic δ15N values while also preserving detailed information about planktonic ecosystem structure.

  12. Chlorine isotope behavior during prograde metamorphism of sedimentary rocks

    NASA Astrophysics Data System (ADS)

    Selverstone, Jane; Sharp, Zachary D.

    2015-05-01

    Chlorine stable isotope compositions of two sedimentary sequences and their metamorphic equivalents were measured in order to study fractionation effects during prograde metamorphism and devolatilization. Protoliths (n = 25) were collected from a 50 m section of Triassic fluvial and playa-lake strata and Jurassic (Liassic) marine black shales in a well-characterized quarry. Low greenschist to middle amphibolite facies equivalents (n > 80) were collected from the Glarus Alps, Urseren Zone, and Lucomagno region. Bulk δ37Cl values are constant within individual sedimentary layers, but vary from -2.0 to + 2.4 ‰ in Triassic rocks and from -3.0 to 0‰ in the black shales. Dolomitic and gypsiferous samples have positive δ37Cl values, but marls and shales are isotopically negative. Bulk Cl contents show only small declines during the earliest stages of metamorphism. Metamorphic equivalents of the Triassic and Liassic protoliths record the same overall ranges in δ37Cl as their protoliths. Samples with highly correlated bulk compositions but different metamorphic grade show no statistically significant difference in δ37Cl. These data lead to the following conclusions: (1) Terrestrial and marine sedimentary rocks display large primary heterogeneities in chlorine isotope composition. As a result, an unambiguous "sedimentary signature" does not exist in the chlorine stable isotope system. (2) No isotopic fractionation is discernable during metamorphic devolatilization, even at low temperatures. Alpine-style metamorphism thus has little to no effect on bulk chlorine isotopic compositions, despite significant devolatilization. (3) Cl is largely retained in the rocks during devolatilization, contrary to the normally assumed hydrophilic behavior of chlorine. Continuous release of mixed-volatile C-O-H fluids likely affected Cl partitioning between fluid and minerals and allowed chlorine to remain in the rocks. (4) There is no evidence for fluid communication across (meta)sedimentary

  13. Ecosystem development following deglaciation: A new sedimentary record from Devils Lake, Wisconsin, USA

    NASA Astrophysics Data System (ADS)

    Williams, Joseph J.; McLauchlan, Kendra K.; Mueller, Joshua R.; Mellicant, Emily M.; Myrbo, Amy E.; Lascu, Ioan

    2015-10-01

    Processes and rates of ecosystem development can be reconstructed using lacustrine sedimentary sequences, but this approach often requires records that contain the start of primary succession. Most lakes in the upper Midwestern U.S. were formed by glaciers at the end of the last Ice Age approximately 11,700 cal yr BP. Devils Lake, Wisconsin is a rare example of a lake from this region whose sediments extend into the Pleistocene and may include the Last Glacial Maximum. Sediment magnetic, geochemical, pollen, and charcoal records were generated from a 10 m core whose basal sediments may be 28,000 years old. Together with a previously published pollen record, these proxies combine to reveal a history of long-term climatic, vegetative and geologic change during the late Pleistocene to Holocene. We identify six sedimentary units that indicate a series of consecutive events rather than a predictable trajectory of ecosystem development at the site. Productivity in the lake was low during the late Pleistocene and increased during the Holocene, as reflected by the sediment lithology, which shows a sudden shift from glacial vivianite-rich and organic-poor clastic-dominated sediments to Holocene diatomaceous sapropels. Several important processes initiated around 17,000 cal yr BP, including the onset of organic matter accumulation and fire in the terrestrial ecosystem. However, the post-glacial landscape was not devoid of vegetation because pollen assemblages indicate that terrestrial vegetation, likely a spruce tundra, survived near the site. A switch to a hardwood forest period during the Holocene also led to a change in the fire regime, with increased frequency of burning. Aquatic ecosystem productivity lagged terrestrial ecosystem productivity throughout the record. Nutrient cycling (as recorded by sedimentary δ15N) was variable but not directional, and appeared to be correlated with climate conditions early in the record, and terrestrial ecosystem processes later in

  14. Magnetostratigraphy of the middle-upper Jurassic sedimentary sequences at Yanshiping, Qiangtang Basin, China

    NASA Astrophysics Data System (ADS)

    Song, Chunhui; Zeng, Yongyao; Yan, Maodu; Wu, Song; Fang, Xiaomin; Bao, Jing; Zan, Jinbo; Liu, Xifang

    2016-09-01

    A series of important geological events occurred in the Tibetan Plateau area during the Jurassic, such as the collision of the Lhasa and Qiangtang Terranes, the closure of the Meso-Tethyan Ocean, the opening of the Neo-Tethyan Ocean and the cessation of the mega-monsoon. The ˜3000 m thick Jurassic sedimentary sequence in the Qiangtang Basin on the central Tibetan Plateau, which is called the Yanshiping (YSP) Group, recorded these geological events. However, the chronology of the sequence is surprisingly poorly constrained. Here, we perform a detailed palaeomagnetic analysis on the ˜1060 m thick middle and upper portions of the YSP Group (the Xiali and Suowa Formations) in the YSP section of the eastern Qiangtang Basin. Three bivalve zones at stratigraphic intervals of ˜40-140, 640-800 and 940-1040 m are identified, which yield a Bathonian-Callovian age for the Lower Xiali Fm., a Callovian-Oxfordian age for the Lower Suowa Fm. and an Oxfordian-Kimmeridgian age for the Upper Suowa Fm. A total of 544 oriented palaeomagnetic samples were collected from the section. By combining thermal and alternating field demagnetizations, clear characteristic remanent magnetization (ChRM) directions are isolated for most of the samples. The robust ChRM directions pass fold and reversals tests, which support the primary nature of the ChRMs and yield a palaeopole at 76.8°N/297.2°E (dp = 2.2°, dm = 3.7°). A total of 27 normal and 26 reversed polarity zones were successfully recorded in the section. Combined with fossil age constraints, results suggest that the section is plausibly composed of a Callovian-Early Kimmeridgian age sedimentary sequence.

  15. Pore water colloid properties in argillaceous sedimentary rocks.

    PubMed

    Degueldre, Claude; Cloet, Veerle

    2016-11-01

    The focus of this work is to evaluate the colloid nature, concentration and size distribution in the pore water of Opalinus Clay and other sedimentary host rocks identified for a potential radioactive waste repository in Switzerland. Because colloids could not be measured in representative undisturbed porewater of these host rocks, predictive modelling based on data from field and laboratory studies is applied. This approach allowed estimating the nature, concentration and size distributions of the colloids in the pore water of these host rocks. As a result of field campaigns, groundwater colloid concentrations are investigated on the basis of their size distribution quantified experimentally using single particle counting techniques. The colloid properties are estimated considering data gained from analogue hydrogeochemical systems ranging from mylonite features in crystalline fissures to sedimentary formations. The colloid concentrations were analysed as a function of the alkaline and alkaline earth element concentrations. Laboratory batch results on clay colloid generation from compacted pellets in quasi-stagnant water are also reported. Experiments with colloids in batch containers indicate that the size distribution of a colloidal suspension evolves toward a common particle size distribution independently of initial conditions. The final suspension size distribution was found to be a function of the attachment factor of the colloids. Finally, calculations were performed using a novel colloid distribution model based on colloid generation, aggregation and sedimentation rates to predict under in-situ conditions what makes colloid concentrations and size distributions batch- or fracture-size dependent. The data presented so far are compared with the field and laboratory data. The colloid occurrence, stability and mobility have been evaluated for the water of the considered potential host rocks. In the pore water of the considered sedimentary host rocks, the clay

  16. Subcritical water extraction of organic matter from sedimentary rocks.

    PubMed

    Luong, Duy; Sephton, Mark A; Watson, Jonathan S

    2015-06-16

    Subcritical water extraction of organic matter containing sedimentary rocks at 300°C and 1500 psi produces extracts comparable to conventional solvent extraction. Subcritical water extraction of previously solvent extracted samples confirms that high molecular weight organic matter (kerogen) degradation is not occurring and that only low molecular weight organic matter (free compounds) are being accessed in analogy to solvent extraction procedures. The sedimentary rocks chosen for extraction span the classic geochemical organic matter types. A type I organic matter-containing sedimentary rock produces n-alkanes and isoprenoidal hydrocarbons at 300°C and 1500 psi that indicate an algal source for the organic matter. Extraction of a rock containing type II organic matter at the same temperature and pressure produces aliphatic hydrocarbons but also aromatic compounds reflecting the increased contributions from terrestrial organic matter in this sample. A type III organic matter-containing sample produces a range of non-polar and polar compounds including polycyclic aromatic hydrocarbons and oxygenated aromatic compounds at 300°C and 1500 psi reflecting a dominantly terrestrial origin for the organic materials. Although extraction at 300°C and 1500 psi produces extracts that are comparable to solvent extraction, lower temperature steps display differences related to organic solubility. The type I organic matter produces no products below 300°C and 1500 psi, reflecting its dominantly aliphatic character, while type II and type III organic matter contribute some polar components to the lower temperature steps, reflecting the chemical heterogeneity of their organic inventory. The separation of polar and non-polar organic compounds by using different temperatures provides the potential for selective extraction that may obviate the need for subsequent preparative chromatography steps. Our results indicate that subcritical water extraction can act as a suitable

  17. Chemical composition of sedimentary rocks in California and Hawaii

    USGS Publications Warehouse

    Hill, Thelma P.

    1981-01-01

    A compilation of published chemical analyses of sedimentary rocks of the United States was undertaken by the U.S. Geological Survey in 1952 to make available scattered data that are needed for a wide range of economic and scientific uses. About 20,000-25,000 chemical analyses of sedimentary rocks in the United States have been published. This report brings together 2,312 of these analyses from California and Hawaii. The samples are arranged by general lithologic characteristics and locality. Indexes of stratigraphy, rock name, commercial uses, and minor elements are provided. The sedimentary rocks are classified into groups and into categories according to the chemical analyses. The groups (A through F2) are defined by a system similar to that proposed by Brian Mason in 1952, in which the main parameters are the three major components of sedimentary rocks: (1) uncombined silica, (2) clay (R203 ? 3Si02 ? nH20), and (3) calcium-magnesium carbonate. The categories are based on the degree of admixture of these three major components with other components, such as sulfate, phos- phate, and iron oxide. Common-rock, mixed-rock, and special-rock categories apply to rocks consisting of 85 percent or more, 50-84 percent, and less than 49 percent, respectively, of the three major components combined. Maps show distribution of sample localities by States; triangular diagrams show the lithologic characteristics and classification groups. Cumulative-frequency curves of each constituent in each classification group of the common-rock and mixed-rock categories are also included. The numerous analyses may not adequately represent the geochemical nature of the rock types and formations of the region because of sampling bias. Maps showing distribution of sample localities indicate that many of the localities are in areas where, for economic or other reasons, special problems attracted interest. Most of the analyzed rocks tended to be fairly simple in composition - mainly mixtures of

  18. Beryllium-10 in Australasian tektites - Evidence for a sedimentary precursor

    NASA Technical Reports Server (NTRS)

    Pal, D. K.; Moniot, R. K.; Kruse, T. H.; Herzog, G. F.; Tuniz, C.

    1982-01-01

    Each of seven Australasian tektites contains about 100 micron atoms of beryllium-10 (half-life, 1.53 million years) per gram. Cosmic-ray bombardment of the australites cannot have produced the measured amounts of beryllium-10 either at the earth's surface or in space. The beryllium-10 contents of these australites are consistent with a sedimentary precursor that adsorbed from precipitation beryllium-10 produced in the atmosphere. The sediments must have spent several thousand years at the earth's surface within a few million years of the tektite-producing event.

  19. The impact of sedimentary coatings on the diagenetic Nd flux

    NASA Astrophysics Data System (ADS)

    Abbott, April N.; Haley, Brian A.; McManus, James

    2016-09-01

    Because ocean circulation impacts global heat transport, understanding the relationship between deep ocean circulation and climate is important for predicting the ocean's role in climate change. A common approach to reconstruct ocean circulation patterns employs the neodymium isotope compositions of authigenic phases recovered from marine sediments. In this approach, mild chemical extractions of these phases is thought to yield information regarding the εNd of the bottom waters that are in contact with the underlying sediment package. However, recent pore fluid studies present evidence for neodymium cycling within the upper portions of the marine sediment package that drives a significant benthic flux of neodymium to the ocean. This internal sedimentary cycling has the potential to obfuscate any relationship between the neodymium signature recovered from the authigenic coating and the overlying neodymium signature of the seawater. For this manuscript, we present sedimentary leach results from three sites on the Oregon margin in the northeast Pacific Ocean. Our goal is to examine the potential mechanisms controlling the exchange of Nd between the sedimentary package and the overlying water column, as well as the relationship between the εNd composition of authigenic sedimentary coatings and that of the pore fluid. In our comparison of the neodymium concentrations and isotope compositions from the total sediment, sediment leachates, and pore fluid we find that the leachable components account for about half of the total solid-phase Nd, therefore representing a significant reservoir of reactive Nd within the sediment package. Based on these and other data, we propose that sediment diagenesis determines the εNd of the pore fluid, which in turn controls the εNd of the bottom water. Consistent with this notion, despite having 1 to 2 orders of magnitude greater Nd concentration than the bottom water, the pore fluid is still <0.001% of the total Nd reservoir in the

  20. Mineral composition of sedimentary matter in the Caspian Sea

    NASA Astrophysics Data System (ADS)

    Lukashin, V. N.; Lisitzin, A. P.; Dara, O. M.; Kozina, N. V.; Klyuvitkin, A. A.; Novigatsky, A. N.

    2016-11-01

    Data on the mineral composition of sedimentary matter and its fluxes in the sediment system of the Caspian Sea are presented. River runoff, aerosols, particulate matter from sediment traps, and the upper layer (0-1 cm) of bottom sediments are considered. The contents of detrital minerals (quartz, albite, and K-feldspar), clay minerals (illite, chlorite, and kaolinite), and carbonates (calcite, Mg-calcite, dolomite, aragonite, and rhodochrosite) are determined. Gypsum was found in bottom sediments but is absent in the other object of the sediment system.

  1. Bottom-trawling along submarine canyons impacts deep sedimentary regimes

    PubMed Central

    Paradis, Sarah; Puig, Pere; Masqué, Pere; Juan-Díaz, Xènia; Martín, Jacobo; Palanques, Albert

    2017-01-01

    Many studies highlight that fish trawling activities cause seafloor erosion, but the assessment of the remobilization of surface sediments and its relocation is still not well documented. These impacts were examined along the flanks and axes of three headless submarine canyons incised on the Barcelona continental margin, where trawling fleets have been operating for decades. Trawled grounds along canyon flanks presented eroded and highly reworked surface sediments resulting from the passage of heavy trawling gear. Sedimentation rates on the upper canyon axes tripled and quadrupled its natural (i.e. pre-industrialization) values after a substantial increase in total horsepower of the operating trawling fleets between 1960 s and 1970 s. These impacts affected the upper canyon reaches next to fishing grounds, where sediment resuspended by trawling can be transported towards the canyon axes. This study highlights that bottom trawling has the capacity to alter natural sedimentary environments by promoting sediment-starved canyon flanks, and by enhancing sedimentation rates along the contiguous axes, independently of canyons’ morphology. Considering the global mechanisation and offshore expansion of bottom trawling fisheries since the mid-20th century, these sedimentary alterations may occur in many trawled canyons worldwide, with further ecological impacts on the trophic status of these non-resilient benthic communities. PMID:28233856

  2. Subseafloor sedimentary life in the South Pacific Gyre

    PubMed Central

    D'Hondt, Steven; Spivack, Arthur J.; Pockalny, Robert; Ferdelman, Timothy G.; Fischer, Jan P.; Kallmeyer, Jens; Abrams, Lewis J.; Smith, David C.; Graham, Dennis; Hasiuk, Franciszek; Schrum, Heather; Stancin, Andrea M.

    2009-01-01

    The low-productivity South Pacific Gyre (SPG) is Earth's largest oceanic province. Its sediment accumulates extraordinarily slowly (0.1–1 m per million years). This sediment contains a living community that is characterized by very low biomass and very low metabolic activity. At every depth in cored SPG sediment, mean cell abundances are 3 to 4 orders of magnitude lower than at the same depths in all previously explored subseafloor communities. The net rate of respiration by the subseafloor sedimentary community at each SPG site is 1 to 3 orders of magnitude lower than the rates at previously explored sites. Because of the low respiration rates and the thinness of the sediment, interstitial waters are oxic throughout the sediment column in most of this region. Consequently, the sedimentary community of the SPG is predominantly aerobic, unlike previously explored subseafloor communities. Generation of H2 by radiolysis of water is a significant electron-donor source for this community. The per-cell respiration rates of this community are about 2 orders of magnitude higher (in oxidation/reduction equivalents) than in previously explored anaerobic subseafloor communities. Respiration rates and cell concentrations in subseafloor sediment throughout almost half of the world ocean may approach those in SPG sediment. PMID:19561304

  3. Subseafloor sedimentary life in the South Pacific Gyre.

    PubMed

    D'Hondt, Steven; Spivack, Arthur J; Pockalny, Robert; Ferdelman, Timothy G; Fischer, Jan P; Kallmeyer, Jens; Abrams, Lewis J; Smith, David C; Graham, Dennis; Hasiuk, Franciszek; Schrum, Heather; Stancin, Andrea M

    2009-07-14

    The low-productivity South Pacific Gyre (SPG) is Earth's largest oceanic province. Its sediment accumulates extraordinarily slowly (0.1-1 m per million years). This sediment contains a living community that is characterized by very low biomass and very low metabolic activity. At every depth in cored SPG sediment, mean cell abundances are 3 to 4 orders of magnitude lower than at the same depths in all previously explored subseafloor communities. The net rate of respiration by the subseafloor sedimentary community at each SPG site is 1 to 3 orders of magnitude lower than the rates at previously explored sites. Because of the low respiration rates and the thinness of the sediment, interstitial waters are oxic throughout the sediment column in most of this region. Consequently, the sedimentary community of the SPG is predominantly aerobic, unlike previously explored subseafloor communities. Generation of H(2) by radiolysis of water is a significant electron-donor source for this community. The per-cell respiration rates of this community are about 2 orders of magnitude higher (in oxidation/reduction equivalents) than in previously explored anaerobic subseafloor communities. Respiration rates and cell concentrations in subseafloor sediment throughout almost half of the world ocean may approach those in SPG sediment.

  4. Manganese mineralogy and diagenesis in the sedimentary rock record

    NASA Astrophysics Data System (ADS)

    Johnson, Jena E.; Webb, Samuel M.; Ma, Chi; Fischer, Woodward W.

    2016-01-01

    Oxidation of manganese (II) to manganese (III,IV) demands oxidants with very high redox potentials; consequently, manganese oxides are both excellent proxies for molecular oxygen and highly favorable electron acceptors when oxygen is absent. The first of these features results in manganese-enriched sedimentary rocks (manganese deposits, commonly Mn ore deposits), which generally correspond to the availability of molecular oxygen in Earth surface environments. And yet because manganese reduction is promoted by a variety of chemical species, these ancient manganese deposits are often significantly more reduced than modern environmental manganese-rich sediments. We document the impacts of manganese reduction and the mineral phases that form stable manganese deposits from seven sedimentary examples spanning from modern surface environments to rocks over 2 billion years old. Integrating redox and coordination information from synchrotron X-ray absorption spectroscopy and X-ray microprobe imaging with scanning electron microscopy and energy and wavelength-dispersive spectroscopy, we find that unlike the Mn(IV)-dominated modern manganese deposits, three manganese minerals dominate these representative ancient deposits: kutnohorite (CaMn(CO3)2), rhodochrosite (MnCO3), and braunite (Mn(III)6Mn(II)O8SiO4). Pairing these mineral and textural observations with previous studies of manganese geochemistry, we develop a paragenetic model of post-depositional manganese mineralization with kutnohorite and calcian rhodochrosite as the earliest diagenetic mineral phases, rhodochrosite and braunite forming secondarily, and later alteration forming Mn-silicates.

  5. Exploration matrix evaluation of sedimentary basins of Colombia

    SciTech Connect

    Kanes, W.H.; Bueno, R.

    1989-03-01

    The sedimentary basins of Colombia are evaluated for the following five exploration criteria: (1) source rock potential, including total organic carbon, Rock-Eval analysis, and kerogen types; (2) seals, with specific units and lithologies designated in each basin; (3) reservoirs characteristics, with stress laid on porosity and permeability fairways developed in the various types of clastic depositional systems; (4) traps, whether structural or stratigraphic, and the most probable routes of hydrocarbon migration; and (5) timing, which also examines the interrelationship between maturation and expulsion of hydrocarbon and the formation of the structural or stratigraphic trap and seal. The exploration matrix is based on delineating the play concepts (up to five) for each sedimentary basin. These play concepts are based on a linear scale based on the probability of future or potential discoveries. All data for the analyses were provided by Ecopetrol and were subjectively weighed only where the number of wells in the basin was low in contrast to the basin area (<1:100 km/sup 2/) and there was no history of production.

  6. Bottom-trawling along submarine canyons impacts deep sedimentary regimes.

    PubMed

    Paradis, Sarah; Puig, Pere; Masqué, Pere; Juan-Díaz, Xènia; Martín, Jacobo; Palanques, Albert

    2017-02-24

    Many studies highlight that fish trawling activities cause seafloor erosion, but the assessment of the remobilization of surface sediments and its relocation is still not well documented. These impacts were examined along the flanks and axes of three headless submarine canyons incised on the Barcelona continental margin, where trawling fleets have been operating for decades. Trawled grounds along canyon flanks presented eroded and highly reworked surface sediments resulting from the passage of heavy trawling gear. Sedimentation rates on the upper canyon axes tripled and quadrupled its natural (i.e. pre-industrialization) values after a substantial increase in total horsepower of the operating trawling fleets between 1960 s and 1970 s. These impacts affected the upper canyon reaches next to fishing grounds, where sediment resuspended by trawling can be transported towards the canyon axes. This study highlights that bottom trawling has the capacity to alter natural sedimentary environments by promoting sediment-starved canyon flanks, and by enhancing sedimentation rates along the contiguous axes, independently of canyons' morphology. Considering the global mechanisation and offshore expansion of bottom trawling fisheries since the mid-20(th) century, these sedimentary alterations may occur in many trawled canyons worldwide, with further ecological impacts on the trophic status of these non-resilient benthic communities.

  7. Bottom-trawling along submarine canyons impacts deep sedimentary regimes

    NASA Astrophysics Data System (ADS)

    Paradis, Sarah; Puig, Pere; Masqué, Pere; Juan-Díaz, Xènia; Martín, Jacobo; Palanques, Albert

    2017-02-01

    Many studies highlight that fish trawling activities cause seafloor erosion, but the assessment of the remobilization of surface sediments and its relocation is still not well documented. These impacts were examined along the flanks and axes of three headless submarine canyons incised on the Barcelona continental margin, where trawling fleets have been operating for decades. Trawled grounds along canyon flanks presented eroded and highly reworked surface sediments resulting from the passage of heavy trawling gear. Sedimentation rates on the upper canyon axes tripled and quadrupled its natural (i.e. pre-industrialization) values after a substantial increase in total horsepower of the operating trawling fleets between 1960 s and 1970 s. These impacts affected the upper canyon reaches next to fishing grounds, where sediment resuspended by trawling can be transported towards the canyon axes. This study highlights that bottom trawling has the capacity to alter natural sedimentary environments by promoting sediment-starved canyon flanks, and by enhancing sedimentation rates along the contiguous axes, independently of canyons’ morphology. Considering the global mechanisation and offshore expansion of bottom trawling fisheries since the mid-20th century, these sedimentary alterations may occur in many trawled canyons worldwide, with further ecological impacts on the trophic status of these non-resilient benthic communities.

  8. Determination of petrophysical properties of sedimentary rocks by optical methods

    NASA Astrophysics Data System (ADS)

    Korte, D.; Kaukler, D.; Fanetti, M.; Cabrera, H.; Daubront, E.; Franko, M.

    2017-04-01

    Petrophysical properties of rocks (thermal diffusivity and conductivity, porosity and density) as well as the correlation between them are of great importance for many geoscientific applications. The porosity of the reservoir rocks and their permeability are the most fundamental physical properties with respect to the storage and transmission of fluids, mainly oil characterization. Accurate knowledge of these parameters for any hydrocarbon reservoir is required for efficient development, management, and prediction of future performance of the oilfield. Thus, the porosity and permeability, as well as the chemical composition must be quantified as precisely as possible. This should be done along with the thermal properties, density, conductivity, diffusivity and effusivity that are intimately related with them. For this reason, photothermal Beam Deflection Spectrometry (BDS) technique for determination of materials' thermal properties together with other methods such as Energy Dispersive X-ray Scanning Electron Microscopy (SEM-EDX) for determining the chemical composition and sample structure, as well as optical microscopy to determine the particles size, were applied for characterization of sedimentary rocks. The rocks were obtained from the Andes south flank in the Venezuela's western basin. The validation of BDS applicability for determination of petrophysical properties of three sedimentary rocks of different texture and composition (all from Late Cretaceous associated with the Luna, Capacho and Colón-Mito Juan geological formations) was performed. The rocks' thermal properties were correlated to the microstructures and chemical composition of the examined samples.

  9. Distribution of sedimentary mercury off Svalbard, European Arctic.

    PubMed

    Bełdowski, J; Miotk, M; Zaborska, A; Pempkowiak, J

    2015-03-01

    The European Arctic, including the Svalbard archipelago, receives mercury loads due to long range atmospheric transport, local contamination, melting of glaciers and as a result of bedrock weathering. Few studies have been devoted to the contamination history and sources of sedimentary mercury in the Svalbard area. This knowledge gap is addressed in this study. Concentrations of total mercury (10-80ng/g), fractions of mercury differing with affinity to the sediment matrix (88-97% refractory, 3-12% mobile), organic and methyl mercury (100-500pg/g) were measured in surface and subsurface sediments in the Spitsbergen fjords and in the Barents Sea off Svalbard. The atmospheric mercury signal can be observed in the Barents Sea, while in the Svalbard fjords it is strongly modified by supply of mercury from natural sources that may include weathering of rocks and glaciers melting, all modified by organic matter supply. Sedimentary methyl mercury concentrations seem to be dependent on environmental factors affecting mercury methylation rather than on location of sampling stations.

  10. Planktonic and sedimentary bacterial diversity of Lake Sayram in summer

    PubMed Central

    Fang, Lei; Chen, Lei; Liu, Yuan; Tao, Wei; Zhang, Zhongzhe; Liu, Haiying; Tang, Yong

    2015-01-01

    Lake Sayram is an ancient cold water lake locating at a mountain basin in Xinjiang, China. The lake water is brackish, alkaline, unpolluted, and abundant in SO42− and Mg2+. The lacustrine ecosystem of Lake Sayram has been intensely investigated. However, profiles of the microbial communities in the lake remain largely unknown. In this study, taxonomic compositions of the planktonic and sedimentary bacterial communities in Lake Sayram were investigated using 16S rRNA metagenomics. The lacustrine bacterial communities were generally structured by environmental conditions, including the hydrological and physicochemical parameters. Proteobacteria was the dominating phylum. In the lake water, the genera Acinetobacter and Ilumatobacter held an absolute predominance, implying their metabolic significance. In the bottom sediment, biogeochemically significant bacteria and thermophilic or acidothermophilic extremophiles were recovered. In contrast to the planktonic bacteria, an appreciable portion of the sedimentary bacteria could not be classified into any known taxonomic unit, indicating the largely unknown bacteriosphere hiding in the bottom sediment of Lake Sayram. PMID:26242906

  11. The thermal stability of organic acids in sedimentary basins

    SciTech Connect

    Crossey, L.J. )

    1991-03-01

    Water-soluble organic compounds in subsurface brines directly affect the evolution of porosity and permeability during sedimentary diagenesis. Recent examination of the aqueous thermal degradation of oxalic acid (a naturally occurring dicarboxylic acid) and its anions has implications for the thermal stability of dicarboxylic acids under sedimentary basin conditions. Because the thermal stability of these compounds is pH-dependent, consideration of the dissociation behavior of carboxylic acids as a function of temperature is essential for estimating the longevity of difunctional carboxylic acids. Results of burial history models suggest that dicarboxylic acid species may be long-lived in formation waters. Comparison with other experimental studies of carboxylic acids and their anion indicates that acetate stability is greater than formate stability, which is greater than oxalate stability, which is greater than gallate and malonate stability. In addition to the implications of natural systems, the aqueous degradation behavior is critical in evaluating other types of experimental results; notably mineral dissolution studies performed at elevated temperatures in the presence of organic materials and hydrous pyrolysis experiments involving kerogens.

  12. Isolation of Geobacter species from diverse sedimentary environments

    USGS Publications Warehouse

    Coaxes, J.D.; Phillips, E.J.P.; Lonergan, D.J.; Jenter, H.; Lovley, D.R.

    1996-01-01

    In an attempt to better understand the microorganisms responsible for Fe(III) reduction in sedimentary environments, Fe(III)-reducing microorganisms were enriched for and isolated from freshwater aquatic sediments, a pristine deep aquifer, and a petroleum-contaminated shallow aquifer. Enrichments were initiated with acetate or toluene as the electron donor and Fe(III) as the electron acceptor. Isolations were made with acetate or benzoate. Five new strains which could obtain energy for growth by dissimilatory Fe(III) reduction were isolated. All five isolates are gram- negative strict anaerobes which grow with acetate as the electron donor and Fe(III) as the electron acceptor. Analysis of the 16S rRNA sequence of the isolated organisms demonstrated that they all belonged to the genus Geobacter in the delta subdivision of the Proteobacteria. Unlike the type strain, Geobacter metallireducens, three of the five isolates could use H2 as an electron donor fur Fe(III) reduction. The deep subsurface isolate is the first Fe(III) reducer shown to completely oxidize lactate to carbon dioxide, while one of the freshwater sediment isolates is only the second Fe(III) reducer known that can oxidize toluene. The isolation of these organisms demonstrates that Geobacter species are widely distributed in a diversity of sedimentary environments in which Fe(III) reduction is an important process.

  13. {sup 210}Pb dating of sediments from the central and the northern Adriatic Sea: The deposition and preservation of sedimentary organic carbon

    SciTech Connect

    Hamilton, T.; Fowler, S.; Miquel, J.C.; La Rosa, J.

    1996-04-01

    A central goal of the ELNA project is to assess the carbon assimilation capacity of the Northern Adriatic Sea. This requires fundamental quantitative information on budgets and sinks of organic carbon. Any change in carbon production in the water column should be reflected in the underlying sediments. Moreover, the fraction of particulate organic carbon reaching the sea floor which is subsequently preserved in the sediment will be strongly coupled to sediment accumulation and mixing. In this study a series of box cores were collected in order to characterize a hypothetical eutrophication gradient extending from the Po River outflow region in the north down to the shallow meso-Adriatic depression (Jabuka Pit). The main tasks assigned to IAEA-MEL were to provide {sup 210}Pb derived sedimentation and dry-mass accumulation rates and to examine the possible correlations between sedimentary processes, the deposition and preservation of sedimentary organic carbon and pelagic primary productivity.

  14. Geochemistry of dispersed sedimentary matter and its fluxes in the water column of the Caspian Sea

    NASA Astrophysics Data System (ADS)

    Lukashin, V. N.; Lisitzin, A. P.

    2016-09-01

    The first data on the chemical composition of dispersed matter from sedimentary traps are reported. The suspended components of sedimentary matter (amorphous silica, organic matter, carbonates, and lithogenic material, as well as Fe, Mn, and minor elements) are considered. As a result, it is shown that the intraannual variability in vertical fluxes of sedimentary matter is characterized by a seasonal increase in spring and autumn. The high fluxes of the components of sedimentary matter on the northern and southern slopes of the Derbent Basin in winter are explained by precipitation of material from the nepheloid layer that forms over the contour current.

  15. Plio-Pleistocene drainage development in an inverted sedimentary basin: Vera basin, Betic Cordillera, SE Spain

    NASA Astrophysics Data System (ADS)

    Stokes, Martin

    2008-08-01

    The Vera basin is one of a series of interconnected Neogene-Quaternary sedimentary basins located within the Internal Zone of the Betic Cordillera (southeast Spain). Since the Pliocene the Vera basin has been subjected to low uplift rates (11-21 m Ma - 1 ) and inverted via compressive tectonics that are related to the ongoing oblique collision between the African and Iberian plates. Within this paper the sedimentary and geomorphic response to basin inversion is explored. Sedimentary processes and environments are established for key stratigraphic units of the Pliocene/Plio-Pleistocene basin fill and Pleistocene dissectional landscape. These data are subsequently utilised to reconstruct an evolving basin palaeogeography. Fault and uplift data are employed to discuss the role of tectonically driven basin inversion for controlling the resultant palaeogeographic changes and associated patterns of drainage development. During the Early-Mid Pliocene the Vera basin was characterised by shallow marine shelf conditions (Cuevas Formation). A major palaeogeographic reorganisation occurred during the Mid-Late Pliocene. Strike-slip movement along the eastern basin margin, coupled with uplift and basin emergence created a protected, partially enclosed marine embayment that was conducive for Gilbert-type fan-delta sedimentation from fluvial inputs along the northern and eastern basin margins (Espíritu Santo Formation). The Vera basin then became fully continental and internally drained through the development of a consequent drainage network that formed following the withdrawal of marine conditions during the Late Pliocene to Early Pleistocene. Alluvial fans developed along the northern and western basin margins, grading to a bajada and terminating in a playa lake in central basin areas (Salmerón Formation). During the Early-Mid Pleistocene a switch from basin infilling to dissection took place, recorded by alluvial fan incision, a switch to braided river sedimentation and

  16. Hydraulic jumps within pyroclastic density currents and their sedimentary record

    NASA Astrophysics Data System (ADS)

    Douillet, G.; Mueller, S.; Kueppers, U.; Dingwell, D. B.

    2013-12-01

    This contribution presents a complete and comprehensive formulation of the hydraulic jump phenomenon and reviews sedimentary structures that may be associated with them. Beginning from the general fluid phenomenon, we then focus on examples from pyroclastic density currents in order to infer dynamic parameters on the parent flows. A hydraulic jump is a fluid dynamics phenomenon that corresponds to the sudden increase of the thickness of a flow accompanied by a decrease of its velocity and/or density. A hydraulic jump is the expression of the transition of the flow from two different flow regimes: supercritical to subcritical. This entrains a change in the energy balance between kinetic energy and gravity potential energy. Recently, the terms of 'pneumatic jumps' have been used for similar phenomenon driven within a gas phase, and granular jumps for dense granular flows. It is thought that such strong changes in the flow conditions may leave characteristic structures in the sedimentary record. Indeed, the main variables influencing the sedimentation rate are the flow velocity, particle concentration and turbulence level, all of them strongly affected by a hydraulic jump. Structures deposited by hydraulic/pneumatic jumps have been called cyclic steps and chute and pool structures. Chute and pools represent the record of a single supercritical to subcritical transition, whereas cyclic steps are produced by stable trains of hydraulic jumps and subsequent re-accelerations. Pyroclastic density currents (PDCs) are gas and pyroclasts flows. As such, they can be subjected to granular and pneumatic jumps and their deposit have often been interpreted as containing records of jumps. Steep sided truncations covered by lensoidal layers have been interpreted as the record of internal jumps within density stratified flows. Fines-depleted breccias at breaks in slope are thought to result from the enhanced turbulence at a jump of the entire flow. Sudden increases in thickness of

  17. Geochemical evolution of groundwater in sequences of sedimentary rocks

    NASA Astrophysics Data System (ADS)

    Palmer, Carl D.; Cherry, John A.

    1984-12-01

    A geochemical mass-transfer model (WATEGM-SE) is used to illustrate the effect of several major processes on the chemical evolution of groundwater flowing through hypothetical sequences of sedimentary rocks. Using chemical reactions prevalent in these rock types, the simulations demonstrate the influence of the initial soil PCO 2, temperature, pressure and the sequence of encounter of the mineral phases along the flow path of the groundwater. The evolution of groundwater in different sequences of limestone and dolostone is simulated with a range of initial PCO 2 -values typical of natural soils. Temperatures of 10° and 25°C are used. The simulations indicate that appreciable differences in the chemical composition of the groundwater and the spring-discharge water will occur, depending on whether a limestone or dolostone unit is first encountered. The cases of more complex stratigraphy are represented by three hypothetical sequences in which each stratum has only one reactive mineral phase. The reactions used in these simulations include calcite dissolution and precipitation, gypsum dissolution and precipitation, cation exchange, and the weathering of albite to kaolinite. Sulfate reduction occurs in the last stratum in each of these sequences. The strata in the three sequences are indentical except for the order in which they are encountered by the groundwater. Considerably different hydrochemistries are calculated for each of these sequences even within the same types of rock units. The effect of increasing total pressure is demonstrated with a water initially saturated with both gypsum and calcite under a pressure of 1 bar. The system is then closed and the pressure is increased to 1 kbar while the temperature remains constant at 25°C. The results indicate that pressure has a significant effect above 50 bar or 500 m hydrostatic head. It is commonly expected that groundwater in sedimentary rocks will exhibit trends in chemistry that are the result of the length

  18. Hydrogeologic framework of fractured sedimentary rock, Newark Basin, New Jersey

    USGS Publications Warehouse

    Lacombe, Pierre J.; Burton, William C.

    2010-01-01

    The hydrogeologic framework of fractured sedimentary bedrock at the former Naval Air Warfare Center (NAWC), Trenton, New Jersey, a trichloroethylene (TCE)-contaminated site in the Newark Basin, is developed using an understanding of the geologic history of the strata, gamma-ray logs, and rock cores. NAWC is the newest field research site established as part of the U.S. Geological Survey Toxic Substances Hydrology Program, Department of Defense (DoD) Strategic Environmental Research and Development Program, and DoD Environmental Security Technology Certification Program to investigate contaminant remediation in fractured rock. Sedimentary bedrock at the NAWC research site comprises the Skunk Hollow, Byram, and Ewing Creek Members of the Lockatong Formation and Raven Rock Member of the Stockton Formation. Muds of the Lockatong Formation that were deposited in Van Houten cycles during the Triassic have lithified to form the bedrock that is typical of much of the Newark Basin. Four lithotypes formed from the sediments include black, carbon-rich laminated mudstone, dark-gray laminated mudstone, light-gray massive mudstone, and red massive mudstone. Diagenesis, tectonic compression, off-loading, and weathering have altered the rocks to give some strata greater hydraulic conductivity than other strata. Each stratum in the Lockatong Formation is 0.3 to 8 m thick, strikes N65 degrees E, and dips 25 degrees to 70 degrees NW. The black, carbon-rich laminated mudstone tends to fracture easily, has a relatively high hydraulic conductivity and is associated with high natural gamma-ray count rates. The dark-gray laminated mudstone is less fractured and has a lower hydraulic conductivity than the black carbon-rich laminated mudstone. The light-gray and the red massive mudstones are highly indurated and tend to have the least fractures and a low hydraulic conductivity. The differences in gamma-ray count rates for different mudstones allow gamma-ray logs to be used to correlate and

  19. Changes in magnetic remanence during simulated deep sedimentary burial

    NASA Astrophysics Data System (ADS)

    Borradaile, Graham J.; Jackson, Mike

    1993-05-01

    Macroscopic hydrostatic compaction of granular rocks causes grain-scale differential stresses as the externally applied load is transmitted through grain contacts. We have compacted rock analogues containing calcite and one of two types of magnetite, bonded with Portland cement. The first type of magnetite is chemically precipitated to give grain sizes in the range 20 nm to 2 μm; these particles were stress-free before compaction. The second type of magnetite was crushed and sieved to a mean grain size of 40 μm; these particles began the experiments in a pre-stressed state. Compaction under confining pressures up to 220 MPa (equivalent to sedimentary compaction at up to 8 km depth) produced strong irreversible changes in the coercivity (and to some extent in other hysteresis parameters) of the samples with initially stress-free magnetite. In contrast, the pre-stressed magnetite exhibited only minimal changes. Composite isothermal remanent magnetisations with orthogonal components in the coercivity ranges 0-30 mT and 30-600 mT were applied prior to compaction. For both sets of samples, the low coercivity component was preferentially progressively demagnetised with increasing compaction stress. This was most efficient for the initially stress-free magnetite. The high coercivity component showed weaker decreases and some spurious increases but there was essentially no change for the samples with pre-stressed magnetite. The changes in magnetic properties of the chemically precipitated magnetite are attributed to the development of dislocation-related impediments to domain wall translation. In contrast, the defect density of the pre-stressed magnetite was acquired under higher differential stresses when it was initially crushed and this was unmodified by the lower experimental stresses. These results may be relevant to the changes expected during rapid sedimentary burial in the absence of pore fluids at low geothermal gradients. One might predict that sedimentary

  20. Strong motion from surface waves in deep sedimentary basins

    USGS Publications Warehouse

    Joyner, W.B.

    2000-01-01

    It is widely recognized that long-period surface waves generated by conversion of body waves at the boundaries of deep sedimentary basins make an important contribution to strong ground motion. The factors controlling the amplitude of such motion, however, are not widely understood. A study of pseudovelocity response spectra of strong-motion records from the Los Angeles Basin shows that late-arriving surface waves with group velocities of about 1 km/sec dominate the ground motion for periods of 3 sec and longer. The rate of amplitude decay for these waves is less than for the body waves and depends significantly on period, with smaller decay for longer periods. The amplitude can be modeled by the equation log y = f(M, RE) + c + bRB where y is the pseudovelocity response, f(M, RE) is an attenuation relation based on a general strong-motion data set, M is moment magnitude, RE is the distance from the source to the edge of the basin, RB is the distance from the edge of the basin to the recording site, and b and c are parameters fit to the data. The equation gives values larger by as much as a factor of 3 than given by the attenuation relationships based on general strong-motion data sets for the same source-site distance. It is clear that surface waves need to be taken into account in the design of long-period structures in deep sedimentary basins. The ground-motion levels specified by the earthquake provisions of current building codes, in California at least, accommodate the long-period ground motions from basin-edge-generated surface waves for periods of 5 sec and less and earthquakes with moment magnitudes of 7.5 or less located more than 20 km outside the basin. There may be problems at longer periods and for earthquakes located closer to the basin edge. The results of this study suggest that anelastic attenuation may need to be included in attempts to model long-period motion in deep sedimentary basins. To obtain better data on surface waves in the future

  1. Application of MSS/LANDSAT images to the structural study of recent sedimentary areas: Campos Sedimentary Basin, Rio de Janeiro, Brazil

    NASA Technical Reports Server (NTRS)

    Parada, N. D. J. (Principal Investigator); Barbosa, M. P.

    1983-01-01

    Visual and computer aided interpretation of MSS/LANDSAT data identified linear and circular features which represent the ""reflexes'' of the crystalline basement structures in the Cenozoic sediments of the emergent part of the Campos Sedimentary Basin.

  2. Test of hyperelasticity in highly nonlinear solids: sedimentary rocks.

    PubMed

    D'Angelo, R M; Winkler, K W; Plona, T J; Landsberger, B J; Johnson, D L

    2004-11-19

    We report measurements of three-wave mixing amplitudes on systems whose third order elastic constants have also been measured by means of the elastoacoustic effect. Because attenuation and diffraction are an important aspect of our measurement technique we analyze our results using a modified Khoklhov-Zabolotskaya-Kuznetsov equation in the frequency domain. We find that the value of beta so deduced for polymethyl methacrylate agrees quite well with that predicted from the stress dependent sound speed measurements, establishing that polymethyl methacrylate may be considered as a hyperelastic solid. The beta values of sedimentary rocks, though they are typically 2 orders of magnitude larger than, e.g., polymethyl methacrylates, are still a factor 3-10 less than those predicted from the elastoacoustic effect.

  3. Research into surface wave phenomena in sedimentary basins

    NASA Astrophysics Data System (ADS)

    Wojcik, G. L.; Isenberg, J.; Ma, F.; Richardson, E.

    1981-12-01

    This study is a continuation of an engineering seismology research effort prompted by the sensitivity of guidance sets in Minuteman Wing V to distant earthquakes. An earlier report considers the probable cause of anomalous patterns of seismic alarms triggered by two North American earthquakes. This report extends the previous study by examining the propagation of surface waves from the 1975 Pocatello Valley, Idaho earthquake sequence across Wyoming to Wing V. In addition, the more general question of surface wave phenomena in sedimentary basins is addressed, particularly the effect of laterally inhomogeneous (dipping) basin-bedrock interfaces. Findings indicate that fundamental and first overtone surface waves are significantly modified by the travel path. In contrast, higher modes are relatively unchanged by the travel path, and affect Wing V in much the same way as body waves considered in the previous study.

  4. Multilayered aquifer modeling in the coastal sedimentary basin of Togo

    NASA Astrophysics Data System (ADS)

    Gnazou, M. D. T.; Sabi, B. E.; Lavalade, J. L.; Schwartz, J.; Akakpo, W.; Tozo, A.

    2017-01-01

    This work is a follow up to the hydrogeological synthesis done in 2012 on the coastal sedimentary basin of Togo. That synthesis notably emphasized the lack of piezometric monitoring in the last thirty years. This has kept us from learning about the dynamics and evolution of the resource in the context of rapidly increasing demand. We are therefore presenting a model for understanding flows, and its main objectives are to provide an initial management tool that should evolve with time as new data (piezometric monitoring, pumping tests, etc.) become available, and to determine what new information can be obtained that will help policy makers to manage the resource better. The results of steady state flow calibration have shown that the aquifer of the Continental Terminal overexploited in the West, can still be exploited in the East of the basin, the Maastrichtian on the whole basin. On the other hand, exploitation of Paleocene aquifers should be done with care.

  5. Sedimentary Facies Analysis Using AVIRIS Data: A Geophysical Inverse Problem

    NASA Technical Reports Server (NTRS)

    Boardmann, Joe W.; Goetz, Alexander F. H.

    1990-01-01

    AVIRIS data can be used to quantitatively analyze and map sedimentary lithofacies. The observed radiance spectra can be reduced to 'apparent reflectance' spectra by topographic and reflectance characterization of several field sites within the image. These apparent reflectance spectra correspond to the true reflectance at each pixel, multiplied by an unknown illumination factor (ranging in value from zero to one). The spatial abundance patterns of spectrally defined lithofacies and the unknown illumination factors can be simultaneously derived using constrained linear spectral unmixing methods. Estimates of the minimum uncertainty in the final results (due to noise, instrument resolutions, degree of illumination and mixing systematics) can be made by forward and inverse modeling. Specific facies studies in the Rattlesnake Hills region of Wyoming illustrate the successful application of these methods.

  6. Geochemistry of approximately 1.9 Ga sedimentary rocks from northeastern Labrador, Canada.

    PubMed

    Hayashi, K I; Fujisawa, H; Holland, H D; Ohmoto, H

    1997-01-01

    Fifty-eight rock chips from fifteen samples of sedimentary rocks from the Ramah Group (approximately 1.9 Ga) in northeastern Labrador, Canada, were analyzed for major and minor elements, including C and S, to elucidate weathering processes on the Earth's surface about 1.9 Ga ago. The samples come from the Rowsell Harbour, Reddick Bight, and Nullataktok Formations. Two rock series, graywackes-gray shales of the Rowsell Harbour, Reddick Bight and Nullataktok Formations, and black shales of the Nullataktok Formation, are distinguishable on the basis of lithology, mineralogy, and major and trace element chemistry. The black shales show lower concentrations than the graywackes-gray shales in TiO2 (0.3-0.7 wt% vs. 0.7-1.8 wt%), Al2O3 (9.5-20.1 wt% vs. 13.0-25.0 wt%), and sigma Fe (<1 wt% vs. 3.8-13.9 wt% as FeO). Contents of Zr, Th, U, Nb, Ce, Y, Rb, Y, Co, and Ni are also lower in the black shales. The source rocks for the Ramah Group sediments were probably Archean gneisses with compositions similar to those in Labrador and western Greenland. The major element chemistry of source rocks for the Ramah Group sedimentary rocks was estimated from the Al2O3/TiO2 ratios of the sedimentary rocks and the relationship between the major element contents (e.g., SiO2 wt%) and Al2O3/TiO2 ratios of the Archean gneisses. This approach is justified, because the Al/Ti ratios of shales generally retain their source rock values; however, the Zr/Al, Zr/Ti, and Cr/Ni ratios fractionate during the transport of sediments. The measured SiO2 contents of shales in the Ramah Group are generally higher than the estimated SiO2 contents of source rocks by approximately 5 wt%. This correction may also have to be applied when estimating average crustal compositions from shales. Two provenances were recognized for the Ramah Group sediments. Provenance I was comprised mostly of rocks of bimodal compositions, one with SiO2 contents approximately 45 wt% and the other approximately 65 wt%, and was the

  7. Geochemistry of approximately 1.9 Ga sedimentary rocks from northeastern Labrador, Canada

    NASA Technical Reports Server (NTRS)

    Hayashi, K. I.; Fujisawa, H.; Holland, H. D.; Ohmoto, H.

    1997-01-01

    Fifty-eight rock chips from fifteen samples of sedimentary rocks from the Ramah Group (approximately 1.9 Ga) in northeastern Labrador, Canada, were analyzed for major and minor elements, including C and S, to elucidate weathering processes on the Earth's surface about 1.9 Ga ago. The samples come from the Rowsell Harbour, Reddick Bight, and Nullataktok Formations. Two rock series, graywackes-gray shales of the Rowsell Harbour, Reddick Bight and Nullataktok Formations, and black shales of the Nullataktok Formation, are distinguishable on the basis of lithology, mineralogy, and major and trace element chemistry. The black shales show lower concentrations than the graywackes-gray shales in TiO2 (0.3-0.7 wt% vs. 0.7-1.8 wt%), Al2O3 (9.5-20.1 wt% vs. 13.0-25.0 wt%), and sigma Fe (<1 wt% vs. 3.8-13.9 wt% as FeO). Contents of Zr, Th, U, Nb, Ce, Y, Rb, Y, Co, and Ni are also lower in the black shales. The source rocks for the Ramah Group sediments were probably Archean gneisses with compositions similar to those in Labrador and western Greenland. The major element chemistry of source rocks for the Ramah Group sedimentary rocks was estimated from the Al2O3/TiO2 ratios of the sedimentary rocks and the relationship between the major element contents (e.g., SiO2 wt%) and Al2O3/TiO2 ratios of the Archean gneisses. This approach is justified, because the Al/Ti ratios of shales generally retain their source rock values; however, the Zr/Al, Zr/Ti, and Cr/Ni ratios fractionate during the transport of sediments. The measured SiO2 contents of shales in the Ramah Group are generally higher than the estimated SiO2 contents of source rocks by approximately 5 wt%. This correction may also have to be applied when estimating average crustal compositions from shales. Two provenances were recognized for the Ramah Group sediments. Provenance I was comprised mostly of rocks of bimodal compositions, one with SiO2 contents approximately 45 wt% and the other approximately 65 wt%, and was the

  8. Geochemistry of ˜1.9 Ga sedimentary rocks from northeastern Labrador, Canada

    NASA Astrophysics Data System (ADS)

    Hayashi, Ken-Ichiro; Fujisawa, Hiroyuki; Holland, Heinrich D.; Ohmoto, Hiroshi

    1997-10-01

    Fifty-eight rock chips from fifteen samples of sedimentary rocks from the Ramah Group (˜1.9 Ga) in northeastern Labrador, Canada, were analyzed for major and minor elements, including C and S, to elucidate weathering processes on the Earth's surface about 1.9 Ga ago. The samples come from the Rowsell Harbour, Reddick Bight, and Nullataktok Formations. Two rock series, graywacke-gray shales of the Rowsell Harbour, Reddick Bight and Nullataktok Formations, and black shales of the Nullataktok Formation, are distinguishable on the basis of lithology, mineralogy, and major and trace element chemistry. The black shales show lower concentrations than the graywackes-gray shales in TiO 2 (0.3-0.7 wt% vs. 0.7-1.8 wt%), Al 20 3 (9.5-20.1 wt% vs. 13.0-25.0 wt%), and ΣFe (<1 wt% vs. 3.8-13.9 wt% vs FeO). Contents of Zr, Th, U, Nb, Ce, Y, Rb, Y, Co, and Ni are also lower in the black shales. The source rocks for the Ramah Group sediments were probably Archean gneisses with compositions similar to those in Labrador and western Greenland. The major element chemistry of source rocks for the Ramah Group sedimentary rocks was estimated from the Al2O3/TiO2 ratios of the sedimentary rocks and the relationship between the major element contents (e.g., SiO 2 wt%) and Al2O3/TiO2 ratios of the Archean gneisses. This approach is justified, because the Al/Ti ratios of shales generally retain their source rock values; however, the Zr/Al, Zr/Ti, and Cr/Ni ratios fractionate during the transport of sediments. The measured SiO 2 contents of shales in the Ramah Group are generally higher than the estimated SiO 2 contents of source rocks by ˜5 wt%. This correction may also have to be applied when estimating average crustal compositions from shales. Two provenances were recognized for the Ramah Group sediments. Provenance I was comprised mostly of rocks of bimodal compositions, one with SiO 2 contents ˜45 wt% and the other ˜65 wt%, and was the source for most sedimentary rocks of the Ramah

  9. The Effect of Confining Pressure on the Chemical Osmotic Property of Sedimentary Rock

    NASA Astrophysics Data System (ADS)

    Takeda, M.; Manaka, M.; Ito, K.

    2011-12-01

    In coastal, sedimentary formations, salinity gradients may induce chemical osmosis, leading to fluid pressure anomalies from hydrostatic pressures. For the precise characterization of the groundwater flow and mass transport systems with heterogeneous salinity distributions, the possibility of chemical osmosis needs to be identified. In order to test the ability of rock to generate pressure anomalies under salinity gradient, the authors developed a laboratory apparatus for measuring the chemically induced osmotic pressure within a rock sample under confining pressure. A series of experiments were performed on a disc-shaped siliceous mudstone, taken from Horonobe area in Hokkaido, under confining pressures ranging from 1 to 20 MPa. The salinity differences between the boundaries of sample are almost consistent in the experiments, and range from 0.110 to 0.118 M NaCl. The differential pressures between the boundaries of sample reached the quasi-steady state within 3 hours in each experiment, and their averaged values range from 9.1 to 26.4 kPa. The reflection coefficients approximated from the salinity and pressure differences using van't Hoff equation range from 0.020 to 0.049, and show the correlation with the confining pressure.

  10. Sea-floor character and sedimentary processes of Great Round Shoal Channel, offshore Massachusetts

    USGS Publications Warehouse

    Poppe, Lawrence J.; Ackerman, Seth D.; Foster, David S.; Blackwood, Dann S.; Williams, S. Jeffress; Moser, M.S.; Stewart, H.F.; Glomb, K.A.

    2007-01-01

    The imagery, interpretive data layers, and data presented herein were derived from multibeam echo-sounder and sidescan-sonar data collected in the vicinity of Great Round Shoal Channel, the main passage through shoals located at the eastern entrance to Nantucket Sound, Massachusetts, and from the stations occupied to verify these acoustic data (fig. 1). Basic data layers show sea-floor topography, sun-illuminated shaded relief, and backscatter intensity; interpretive layers show the distributions of surficial sediment, sedimentary environments, and sea-floor features. Presented verification data include sediment grain-size analyses and a gallery of still photographs of the seabed. The multibeam and sidescan data, which together cover an approximately 39.9-km² area of sea floor, were collected during National Oceanic and Atmospheric Administration (NOAA) hydrographic survey H11079 (fig. 1). Although originally collected for charting purposes, these data provide a fundamental framework for research and management activities along this part of the Massachusetts coastline (Noji and others, 2004), show the composition and terrain of the seabed, and provide information on sediment transport and benthic habitat. This publication is the third in a series of U.S. Geological Survey (USGS) digital reports describing the sea-floor geology around Cape Cod. The first focused on the area off the eastern shore of the outer Cape (Poppe and others, 2006); the second on a passage through the Elizabeth Islands (Poppe and others, 2007).

  11. Occurrence of selenium in sulfides from some sedimentary rocks of the western United States

    USGS Publications Warehouse

    Coleman, Robert G.; Delevaux, Maryse

    1956-01-01

    Investigations of the minor- and trace-element content of sulfides associated with uranium ore deposits from sandstone-type deposits have shown that selenium commonly substitutes for sulfur. The Morrison formation and Entrada sandstone of Jurassic age and the Wind River formation of Eocene age seem to be seleniferous stratigraphic zones; sulfides deposited within these formations generally contain abnormal amounts of selenium. The selenium content of the pyrite, marcasite, and chalcocite is much greater than that reported in previously published data. Under the prevailing temperatures and pressures of formation of the Colorado Plateau uranium deposits the maximum amount of Se substituting for S in the pyrite structure was found to be 3 percent by weight. Ferroselite, the iron selenide (FeSe2), was found in two deposits on the Colorado Plateau and it was also established that galena (PbS) forms an isomorphous series with clausthalite (PbSe) in nature. During oxidation of the selenium-bearing sulfides and selenides in the Colorado Plateau and Wyoming, the selenium forms pinkish crusts of either monoclinic or hexagonal native selenium intergrown with soluble sulfates, suggesting that under "normal" oxidizing conditions native selenium is more stable than selenites or selenates. The above-normal selenium content of these sulfides from sedimentary rocks of Mesozoic and Tertiary age is significant. The high selenium in these sulfides is related to periods of volcanic and intrusive activity penecontemporaneous with the formation of the containing sediments.

  12. Correlation between plate motions and tectonic subsidence of sedimentary basins in Africa

    SciTech Connect

    Janssen, M.E. )

    1993-09-01

    From the early Mesozoic until the Holocene, the African continent was generally in a state of extension, based on plate tectonic reconstructions and sedimentary basin subsidence studies. Beginning with the breakup of Gondwana in the Permian-Triassic, this resulted in the formation of the present-day African continental margins and a series of intracontinental rift basins, located mainly on older (late Proterozoic) shear zones. Numerous wells from marginal, as well as intracontinental rift basins, have been backstripped to elucidate their Mesozoic and Tertiary tectonic histories. They show a generally consistent patterns of subsidence and uplift phases in all basins. During the evolution of these basins, the direction of African plate motion changed several times. This was related to the differential opening of the central and south Atlantic oceans, changes in spreading rates in both the Atlantic and Indian oceans, and the collision between Africa and Europe. Episodes of compressional deformation related to these plate tectonic changes are revealed in backstripped tectonic subsidence curves.

  13. A seismic network to investigate the sedimentary hosted hydrothermal Lusi system

    NASA Astrophysics Data System (ADS)

    Javad Fallahi, Mohammad; Mazzini, Adriano; Lupi, Matteo; Obermann, Anne; Karyono, Karyono

    2016-04-01

    The 29th of May 2006 marked the beginning of the sedimentary hosted hydrothermal Lusi system. During the last 10 years we witnessed numerous alterations of the Lusi system behavior that coincide with the frequent seismic and volcanic activity occurring in the region. In order to monitor the effect that the seismicity and the activity of the volcanic arc have on Lusi, we deployed a ad hoc seismic network. This temporary network consist of 10 broadband and 21 short period stations and is currently operating around the Arjuno-Welirang volcanic complex, along the Watukosek fault system and around Lusi, in the East Java basin since January 2015. We exploit this dataset to investigate surface wave and shear wave velocity structure of the upper-crust beneath the Arjuno-Welirang-Lusi complex in the framework of the Lusi Lab project (ERC grant n° 308126). Rayleigh and Love waves travelling between each station-pair are extracted by cross-correlating long time series of ambient noise data recorded at the stations. Group and phase velocity dispersion curves are obtained by time-frequency analysis of cross-correlation functions, and are tomographically inverted to provide 2D velocity maps corresponding to different sampling depths. 3D shear wave velocity structure is then acquired by inverting the group velocity maps.

  14. Modeling of the nonlinear resonant response in sedimentary rocks

    SciTech Connect

    Ten Cate, James A; Shankland, Thomas J; Vakhnenko, Vyacheslav O; Vakhnenko, Oleksiy

    2009-04-03

    We suggest a model for describing a wide class of nonlinear and hysteretic effects in sedimentary rocks at longitudinal bar resonance. In particular, we explain: hysteretic behaviour of a resonance curve on both its upward and downward slopes; linear softening of resonant frequency with increase of driving level; gradual (almost logarithmic) recovery of resonant frequency after large dynamical strains; and temporal relaxation of response amplitude at fixed frequency. Starting with a suggested model, we predict the dynamical realization of end-point memory in resonating bar experiments with a cyclic frequency protocol. These theoretical findings were confirmed experimentally at Los Alamos National Laboratory. Sedimentary rocks, particularly sandstones, are distinguished by their grain structure in which each grain is much harder than the intergrain cementation material. The peculiarities of grain and pore structures give rise to a variety of remarkable nonlinear mechanical properties demonstrated by rocks, both at quasistatic and alternating dynamic loading. Thus, the hysteresis earlier established for the stress-strain relation in samples subjected to quasistatic loading-unloading cycles has also been discovered for the relation between acceleration amplitude and driving frequency in bar-shaped samples subjected to an alternating external drive that is frequency-swept through resonance. At strong drive levels there is an unusual, almost linear decrease of resonant frequency with strain amplitude, and there are long-term relaxation phenomena such as nearly logarithmic recovery (increase) of resonant frequency after the large conditioning drive has been removed. In this report we present a short sketch of a model for explaining numerous experimental observations seen in forced longitudinal oscillations of sandstone bars. According to our theory a broad set of experimental data can be understood as various aspects of the same internally consistent pattern. Furthermore

  15. Consumption and diffusion of dissolved oxygen in sedimentary rocks.

    PubMed

    Manaka, M; Takeda, M

    2016-10-01

    Fe(II)-bearing minerals (e.g., biotite, chlorite, and pyrite) are a promising reducing agent for the consumption of atmospheric oxygen in repositories for the geological disposal of high-level radioactive waste. To estimate effective diffusion coefficients (De, in m(2)s(-1)) for dissolved oxygen (DO) and the reaction rates for the oxidation of Fe(II)-bearing minerals in a repository environment, we conducted diffusion-chemical reaction experiments using intact rock samples of Mizunami sedimentary rock. In addition, we conducted batch experiments on the oxidation of crushed sedimentary rock by DO in a closed system. From the results of the diffusion-chemical reaction experiments, we estimated the values of De for DO to lie within the range 2.69×10(-11)

  16. THE INFLUENCE OF SUBMERGED MACROPHYTES ON SEDIMENTARY DIATOM ASSEMBLAGES(1).

    PubMed

    Vermaire, Jesse C; Prairie, Yves T; Gregory-Eaves, Irene

    2011-12-01

    Submerged macrophytes are a central component of lake ecosystems; however, little is known regarding their long-term response to environmental change. We have examined the potential of diatoms as indicators of past macrophyte biomass. We first sampled periphyton to determine whether habitat was a predictor of diatom assemblage. We then sampled 41 lakes in Quebec, Canada, to evaluate whether whole-lake submerged macrophyte biomass (BiomEpiV) influenced surface sediment diatom assemblages. A multivariate regression tree (MRT) was used to construct a semiquantitative model to reconstruct past macrophyte biomass. We determined that periphytic diatom assemblages on macrophytes were significantly different from those on wood and rocks (ANOSIM R = 0.63, P < 0.01). A redundancy analysis (RDA) of the 41-lake data set identified BiomEpiV as a significant (P < 0.05) variable in structuring sedimentary diatom assemblages. The MRT analysis classified the lakes into three groups. These groups were (A) high-macrophyte, nutrient-limited lakes (BiomEpiV ≥525 μg · L(-1) ; total phosphorus [TP] <35 μg · L(-1) ; 23 lakes); (B) low-macrophyte, nutrient-limited lakes (BiomEpiV <525 μg · L(-1) ; TP <35 μg · L(-1) ; 12 lakes); and (C) eutrophic lakes (TP ≥35 μg · L(-1) ; six lakes). A semiquantitative model correctly predicted the MRT group of the lake 71% of the time (P < 0.001). These results suggest that submerged macrophytes have a significant influence on diatom community structure and that sedimentary diatom assemblages can be used to infer past macrophyte abundance.

  17. [Sedimentary Phosphorus Forms Under Disturbances and Algae in Taihu Lake].

    PubMed

    Chen, Jun; Li, Da-peng; Zhu, Pei-ying; Huang, Yong; Wang, Ren

    2015-12-01

    Sedimentary phosphorus forms were investigated to clarify the release of sedimentary phosphorus forms under the repeated disturbance with the addition of algae at different initial concentrations. The sediments and overlying water were taken from the Meiliang Bay in Taihu Lake. The results showed that the concentrations of NH₄ Cl-P and Res-P decreased, while the content of Fe/Al-P and Ca-P increased without disturbance. In addition, the Ca-P increased with the increase of the initial concentration of algae and the net increase of Ca-P increased by 48% (30 µg · L⁻¹), 66% (60 µg · L⁻¹), 74% (120 µg · L⁻¹), respectively. However, under the disturbance, the NH₄Cl-P and Res-P were significantly reduced, the Fe/Al-P increased significantly. The percentage of Fe/Al-P to Tot-P was up to 66. 2% (average of the 3 experiments with the addition of algae of 30 µg · L⁻¹, 60 µg · L⁻¹ and 120 µg L-¹), it was higher than the value (53.%, average of the 3 experiments) without the disturbance. Moreover, under the disturbance, the percentage of Ca-P to Tot-P was 24.1% (average of the 3 experiments with the addition of algae of 30 µg · L⁻¹, 60 µg⁻¹ and 120 µg · L⁻¹) and it was slightly lower than that (33.0%, average of the 3 experiments) without the disturbance. It is suggested that the coexistence of disturbance and algae facilitated the formation of Fe/Al-P, but the algae accelerated the formation of Ca-P without disturbance.

  18. Consumption and diffusion of dissolved oxygen in sedimentary rocks

    NASA Astrophysics Data System (ADS)

    Manaka, M.; Takeda, M.

    2016-10-01

    Fe(II)-bearing minerals (e.g., biotite, chlorite, and pyrite) are a promising reducing agent for the consumption of atmospheric oxygen in repositories for the geological disposal of high-level radioactive waste. To estimate effective diffusion coefficients (De, in m2 s- 1) for dissolved oxygen (DO) and the reaction rates for the oxidation of Fe(II)-bearing minerals in a repository environment, we conducted diffusion-chemical reaction experiments using intact rock samples of Mizunami sedimentary rock. In addition, we conducted batch experiments on the oxidation of crushed sedimentary rock by DO in a closed system. From the results of the diffusion-chemical reaction experiments, we estimated the values of De for DO to lie within the range 2.69 × 10- 11 < De < 6.30 × 10- 11. Values of the second-order rate constant (k, in L mol-1 s- 1) were in the range - 3.66 < log k < - 2.83 (from batch experiments) and in the range - 3.87 < log k < - 2.22 (from diffusion-chemical reaction experiments). Many of these values are within the range of previously published rates for reaction between O2(aq) and Fe(II) surface complexes. The average value for the total concentration of reactive sites was about 10- 4 mol m- 2 from batch experiments. In contrast, the value of reactive sites estimated from the physical surface area was about 10- 8 mol m- 2, indicating that the reaction within intact rock is limited to the sites that originally existed with accessible porosity for O2(aq). This difference arises because the batch experiments used powdered samples, meaning that new sites which formed during milling were added to the original reaction sites. On the basis of these observations and interpretations, diffusion-chemical reaction experiments make it possible to determine the values of the kinetic parameter and diffusivity for an intact rock sample simultaneously.

  19. Sedimentary lipid biogeochemistry of an hypereutrophic alkaline lagoon

    SciTech Connect

    Grimalt, J.O.; Albaiges, J. ); Yruela, I.; Saizjimenez, C. ); Toja, J. ); Leeuw, J.W. De. )

    1991-09-01

    A detailed study of the lipid composition of sedimentary and water particulate samples of a dilute alkaline lake (Santa Olalla Lagoon, Guadalquivir Delta, southwestern Spain) has allowed the identification and quantitation of about 300 compounds reflecting predominant inputs of organic matter and very early diagenetic processes. These lipids, dominated by fatty acids (80-86%), account for up to 0.25% wt. of dry sediment which is consistent with the high eutrophic conditions of the lagoon and suggests a good preservation of the originally produced organic matter. However, the primary lipid compounds, mainly from cyanobacterial origin, are strongly modified. The C{sub 30}-C{sub 32}, 1,13- and 1,15-diols constitute the only major group that can be attributed directly to these organisms. The predominant lipids, including the fatty acids, are indicative of intense microbial reworking, namely contributions from gram-positive and gram-negative eubacteria and methanogens. Conversely, the higher plant lipids are better preserved and dominate the aliphatic hydrocarbon fraction. Hydrogenation and dehydration are two major transformation processes in the sedimentary system being reflected in the transformation of sterols into 5{alpha}(H)- and 5{beta}(H)-stanols and sterenes, and 17{beta}(H), 21{beta}(H)-hopan-22-ol into diploptene. Oxidation in the water column seems to involve the partial transformation of sterols into steroid ketones, phytol into 5,9,13-trimethyltetradecanoic acid and two isomeric 3,7,11,15-tetramethyl-17-hexadecanolides, and, possibly, tetrahymanol into gammacer-3-one. Adiantone and bishomohopanoic acid probably result from the partial oxydation of extended polyhydroxyhopanes or the C{sub 30}-C{sub 33} hydroxyhopanes found in the lagoon waters.

  20. Sedimentary lipid biogeochemistry of an hypereutrophic alkaline lagoon

    NASA Astrophysics Data System (ADS)

    Grimalt, J. O.; Yruela, I.; Saiz-Jimenez, C.; Toja, J.; de Leeuw, J. W.; Albaigés, J.

    1991-09-01

    A detailed study of the lipid composition of sedimentary and water particulate samples of a dilute alkaline lake (Santa Olalla Lagoon, Guadalquivir Delta, southwestern Spain) has allowed the identification and quantitation of about 300 compounds reflecting predominant inputs of organic matter and very early diagenetic processes. These lipids, dominated by fatty acids (80-86%), account for up to 0.25% wt. of dry sediment which is consistent with the high eutrophic conditions of the lagoon and suggests a good preservation of the originally produced organic matter. However, the primary lipid compounds, mainly from cyanobacterial origin, are strongly modified. The C30-C32, 1,13- and 1,15-diols constitute the only major group that can be attributed directly to these organisms. The predominant lipids, including the fatty acids, are indicative of intense microbial reworking, namely contributions from gram-positive and gram-negative eubacteria and methanogens. Conversely, the higher plant lipids are better preserved and dominate the aliphatic hydrocarbon fraction. Hydrogenation and dehydration are two major transformation processes in the sedimentary system being reflected in the transformation of sterols into 5α(H)- and 5β(H)-stanols and sterenes, and 17β(H),21β(H)-hopan-22-ol into diploptene. Oxidation in the water column seems to involve the partial transformation of sterols into steroid ketones, phytol into 5,9,13-trimethyltetradecanoic acid and two isomeric 3,7,11,15-tetramethyl-17-hexadecanolides, and, possibly, tetrahymanol into gammacer-3-one. Adiantone and bishomohopanoic acid probably result from the partial oxydation of extended polyhydroxyhopanes or the C30-C33 hydroxyhopanes found in the lagoon waters.

  1. Holocene Tectonic and Sedimentary Evolution of Coastal San Diego

    NASA Astrophysics Data System (ADS)

    Maloney, J. M.; Driscoll, N. W.; Brothers, D. S.; Babcock, J. M.; Kent, G.

    2010-12-01

    The shelf and nearshore region of San Diego, California, between La Jolla cove in the north and the U.S.- Mexico border in the south, is an important ecological and economic resource. It contains two of the largest kelp forests in southern California and lies offshore miles of popular beaches. Understanding the interplay between tectonic and sedimentary processes in this area is critical because it will allow us to assess how other forcing functions such as the rapid sea level rise (2 - 3 mm/yr) and predicted climate change associated with global warming are impacting the kelp and nearshore environments. The fault architecture and sedimentary deposits offshore San Diego have been mapped using high-resolution seismic CHIRP profiling. The mapped area lies within the inner California Continental Borderland (CCB), which is characterized by a system of basins and ridges and extensive strike-slip faulting. The CHIRP data clearly images several splays of the Coronado Bank Fault Zone (CBFZ), a major fault in the area, which show recent activity in the upper 30 m of sediment with the most recent deformation at ~4 m below seafloor. Several sediment packages as deep as 50 m below the seafloor are imaged and place important constraints on tectonic deformation and sediment dispersal in the region as well as the earthquake recurrence interval on the CBFZ. Exposed and buried wavecut terraces identified on numerous CHIRP profiles, which can be correlated to terraces mapped regionally, provide insight into tectonic uplift rates and sea-level fluctuations. Finally, the extensive kelp forests offshore Mount Soledad and Point Loma occur where hardgrounds are exposed at the seafloor as a consequence of tectonic uplift. High resolution mapping offshore San Diego is providing new insight into the complex interplay between tectonics, sedimentation, and biology in this ecologically diverse region.

  2. Tectonosedimentary history of the sedimentary basins in northern west Siberia

    SciTech Connect

    Kunin, N.Ya.; Segalovich, I.E. )

    1993-09-01

    Sedimentary basins of northern west Siberia belong to the Arctic tectonosedimentary province. This basin evolved dissimilarly compared to those in the Urengoy and more southern areas, which resulted in substantial differences in the geologic characteristics. Seismic surveys indicate that the basement surface in northern west Siberia occurs at great depths, in places exceeding 15 km. The depressions of the basement surfaces are filled with the thick Paleozoic and Mesozoic sequences. The paper discussed the results of seismostratigraphic analysis of more than 13,000 km of regional common-depth-point profiles. These profiles identified systems of east-west-trending and isometric structures in the region. Some of the structures are buried; others are mapped in the upper horizons of the sedimentary cover and decrease in magnitude with depth. Cretaceous marine sediments that were deposited under deep-water conditions and did not compensate for the tectonic subsidence are widely present in the region. Noncompensated sedimentation was the longest from the Late Jurassic to the Hauterivian-Barremian on the Gydan peninsula and in adjacent areas. The Jurassic section is dominate by ingressive marine sediments. Sediments that did not compensate for tectonic subsidence widely occurred in the Early Jurassic and resulted in deposition of petroleum source rocks. Triassic and Jurassic strata occur conformable in most of northern west Siberia. Significant deformation of the Triassic sediments are identified in the periphery of the Triassic marine basin. This indicates that surrounding structures were thrust against northern west Siberia at the Triassic and Jurassic time boundary. Isometric structures of high magnitude were formed during the Paleozoic structure stage and these structures continued to grow through the Triassic and Jurassic. These and other results of seismostratigraphic analysis suggest the high oil potential of the region.

  3. Predicting the transport properties of sedimentary rocks from microstructure

    SciTech Connect

    Schlueter, Erika M.

    1995-01-01

    Understanding transport properties of sedimentary rocks, including permeability, relative permeability, and electrical conductivity, is of great importance for petroleum engineering, waste isolation, environmental restoration, and other applications. These transport properties axe controlled to a great extent by the pore structure. How pore geometry, topology, and the physics and chemistry of mineral-fluid and fluid-fluid interactions affect the flow of fluids through consolidated/partially consolidated porous media are investigated analytically and experimentally. Hydraulic and electrical conductivity of sedimentary rocks are predicted from the microscopic geometry of the pore space. Cross-sectional areas and perimeters of individual pores are estimated from two-dimensional scanning electron microscope (SEM) photomicrographs of rock sections. Results, using Berea, Boise, Massilon, and Saint-Gilles sandstones show close agreement between the predicted and measured permeabilities. Good to fair agreement is found in the case of electrical conductivity. In particular, good agreement is found for a poorly cemented rock such as Saint-Gilles sandstone, whereas the agreement is not very good for well-cemented rocks. The possible reasons for this are investigated. The surface conductance contribution of clay minerals to the overall electrical conductivity is assessed. The effect of partial hydrocarbon saturation on overall rock conductivity, and on the Archie saturation exponent, is discussed. The region of validity of the well-known Kozeny-Carman permeability formulae for consolidated porous media and their relationship to the microscopic spatial variations of channel dimensions are established. It is found that the permeabilities predicted by the Kozeny-Carman equations are valid within a factor of three of the observed values methods.

  4. PUMa - modelling the groundwater flow in Baltic Sedimentary Basin

    NASA Astrophysics Data System (ADS)

    Kalvane, G.; Marnica, A.; Bethers, U.

    2012-04-01

    In 2009-2012 at University of Latvia and Latvia University of Agriculture project "Establishment of interdisciplinary scientist group and modelling system for groundwater research" is implemented financed by the European Social Fund. The aim of the project is to develop groundwater research in Latvia by establishing interdisciplinary research group and modelling system covering groundwater flow in the Baltic Sedimentary Basin. Researchers from fields like geology, chemistry, mathematical modelling, physics and environmental engineering are involved in the project. The modelling system is used as a platform for addressing scientific problems such as: (1) large-scale groundwater flow in Baltic Sedimentary Basin and impact of human activities on it; (2) the evolution of groundwater flow since the last glaciation and subglacial groundwater recharge; (3) the effects of climate changes on shallow groundwater and interaction of hydrographical network and groundwater; (4) new programming approaches for groundwater modelling. Within the frame of the project most accessible geological information such as description of geological wells, geological maps and results of seismic profiling in Latvia as well as Estonia and Lithuania are collected and integrated into modelling system. For example data form more then 40 thousands wells are directly used to automatically generate the geological structure of the model. Additionally a groundwater sampling campaign is undertaken. Contents of CFC, stabile isotopes of O and H and radiocarbon are the most significant parameters of groundwater that are established in unprecedented scale for Latvia. The most important modelling results will be published in web as a data set. Project number: 2009/0212/1DP/1.1.1.2.0/09/APIA/VIAA/060. Project web-site: www.puma.lu.lv

  5. Sedimentary loading, lithospheric flexure and subduction initiation at passive margins

    SciTech Connect

    Erickson, S.G. . Dept. of Earth Sciences)

    1992-01-01

    Recent theoretical models have demonstrated the difficulty of subduction initiation at passive margins, whether subduction is assumed to initiate by overcoming the shear resistance on a thrust fault through the lithosphere or by failure of the entire lithosphere in bending due to sedimentary loading. A mechanism for subduction initiation at passive margins that overcomes these difficulties incorporates the increased subsidence of a marginal basin during decoupling of a previously locked margin. A passive margin may decouple by reactivation of rift-related faults in a local extensional or strike-slip setting. Flexure of marginal basins by sedimentary loading is modeled here by the bending of infinite and semi-infinite elastic plates under a triangular load. The geometry of a mature marginal basin fits the deflection produced by loading of an infinite plate in which the flexural rigidity of continental lithosphere is larger than that of oceanic lithosphere. Decoupling of such a locked passive margin by fault reactivation may cause the lithospheric bending behavior of the margin to change from that of an infinite plate to that of a semi-infinite plate, with a resultant increase in deflection of the marginal basin. The increase in deflection depends on the flexural rigidities of continental and oceanic lithosphere. For flexural rigidities of 10[sup 30]-10[sup 31] dyn-cm (elastic lithosphere thicknesses 24--51 km), the difference in deflections between infinite and semi-infinite plates is 15--17 km, so that decoupling sinks the top of the oceanic lithosphere to depths of ca 35 km. Additional sedimentation within the basin and phase changes within the oceanic crust may further increase this deflection. Subduction may initiate if the top of the oceanic lithosphere sinks to the base of the adjacent elastic lithosphere.

  6. Radiographic analysis of sedimentary structures and depositional histories in Apollo 15 cores

    NASA Technical Reports Server (NTRS)

    Coch, N. K.

    1977-01-01

    Radiographs of the Apollo 15 deepdrill drive tubes were analyzed on an SDS electronic enhancer to determine sedimentary structures in the core samples. The data obtained were compared with all other Apollo mission radiographs and used to make inferences on the character of sedimentary depositional processes on the lunar surface.

  7. Unification and Infinite Series

    ERIC Educational Resources Information Center

    Leyendekkers, J. V.; Shannon, A. G.

    2008-01-01

    Some infinite series are analysed on the basis of the hypergeometric function and integer structure and modular rings. The resulting generalized functions are compared with differentiation of the "mother" series. (Contains 1 table.)

  8. Sedimentary process control on carbon isotope composition of sedimentary organic matter in an ancient shallow-water shelf succession

    NASA Astrophysics Data System (ADS)

    Davies, S. J.; Leng, M. J.; Macquaker, J. H. S.; Hawkins, K.

    2012-11-01

    Source and delivery mechanisms of organic matter are rarely considered when interpreting changing δ13C through sedimentary successions even though isotope excursions are widely used to identify and correlate global perturbations in the carbon cycle. Combining detailed sedimentology and geochemistry we demonstrate how organic carbon abundance and δ13C values from sedimentary organic matter from Carboniferous-aged mudstones are influenced by the proportion of terrestrial versus water column-derived organic matter. Silt-bearing clay-rich shelf mudstones that were deposited by erosive density flows are characterized by 1.8-2.4% organic carbon and highδ13C values (averaging -22.9 ± 0.3‰, n = 12). Typically these mudstones contain significant volumes of terrestrial plant-derived material. In contrast, clay-rich lenticular mudstones, with a marine macrofauna, are the products of the transport of mud fragments, eroded from pre-existing water-rich shelfal muds, when shorelines were distant and biological productivity in the water column was high. Higher organic carbon (2.1-5.2%) and lowerδ13C values (averaging -24.3 ± 0.5‰, n = 11) characterize these mudstones and are interpreted to reflect a greater contribution by (isotopically more negative) amorphous organic matter derived from marine algae. Differences in δ13C between terrestrial and marine organic matter allow the changing proportions from different sources to be tracked through this succession. Combining δ13C values with zirconium (measured from whole rock), here used as a proxy for detrital silt input, provides a novel approach to distinguishing mudstone provenance and ultimately using δ13C to identify oil-prone organic matter in potential source rocks. These results have important implications for using bulk organic matter to identify and characterize global C-isotope excursions.

  9. Finite element modeling of hydrothermal fluid flow in Peace River Arch of Western Canada Sedimentary Basin: implications for dolomitization

    NASA Astrophysics Data System (ADS)

    Niu, Y.; Yang, J.

    2009-05-01

    A finite element computer modeling approach, integrated with existing geological, geochemical and geophysical data, was used to address the diagenetic process of dolomitization in Western Canada Sedimentary Basin (WCSB). A 2-D conceptualized model was developed to simulate hydrothermal flow in particular for the packland play type dolomitization in Peace River Arch of WCSB. Our numerical results indicate that faults serve as important pathways for the ascending hydrothermal fluids driven by buoyancy force due to temporal and spatial changes in temperature. Both steady state and transient computations were conducted to reveal suitable hydraulic conditions under which the modeled temperature within the aquifer system is consistent with observed values in the targeted study area. A series of numerical case studies were carried out to investigate key factors controlling hydrothermal fluid flow, including fault penetration depth, width and permeability, and its connectivity with the host rock units.

  10. Coseismic growth of sedimentary basins along the Yammouneh strike-slip fault (Lebanon)

    NASA Astrophysics Data System (ADS)

    Nemer, Tony; Gomez, Francisco; Al Haddad, Sharbel; Tabet, Charles

    2008-12-01

    The left-lateral Yammouneh fault (YF) is the main active branch of the Dead Sea Transform Fault (DSTF) within the Lebanese restraining bend. Despite the overall transpressional setting, a series of sedimentary basins have developed along the trace of the YF. Consequently, palaeoseismic studies within these basins provide an opportunity to study the processes of coseismic growth of the basins, as well as elucidate earthquake behaviour of the fault, in general. Geodetic measurements of contemporary fault slip within the Lebanese restraining bend indicate that the YF accommodates most of the expected left-lateral strike-slip motion, despite the apparent lack of present-day seismicity. We studied the YF, using combined investigations of remote imagery, geomorphology and palaeoseismology. The active fault trace along a 51 km strip was delineated as relatively young surface ruptures and fault scarps that affect Holocene deposits with intermittent offset geomorphic markers. Seven closed basins that occur along-strike of the YF, were found to be related to faulting, with at least three of them displaying evident pull-apart settings. We concentrated our work on the rhombohedral Yammouneh basin, an actively evolving example of pull-apart basins, which is presently obliquely cut by the active fault, with an apparently young age of 1.4 +/- 0.3 Myr. 3-D correlation and analysis of palaeoseismic investigations exposed a composite shear zone with a total subsidence that exceeds 1.6 m over the past 4000-4400 yr. Stratigraphic and geochronological constraints suggest the occurrences of at least five large faulting events during that period. By correlating the stratigraphy and ages of this trench with a previously published study located nearby, a combined palaeoseismic history for the past five events is constructed. This suggests a mean recurrence period of 1020-1175 yr for large earthquakes along this section of the YF. Our results suggest a subsidence rate due to faulting of

  11. Oceanographic processes and the preservation of sedimentary structure in Eckernförde Bay, Baltic Sea

    NASA Astrophysics Data System (ADS)

    Nittrouer, Charles A.; Lopez, Glenn R.; Donelson Wright, L.; Bentley, Samuel J.; D'Andrea, Anthony F.; Friedrichs, Carl T.; Craig, Nancy I.; Sommerfield, Christopher K.

    1998-12-01

    The sedimentary structure preserved within the seabed of Eckernförde Bay was investigated together with the oceanographic processes influencing that structure. A series of four cruises were undertaken during winter to summer conditions. An instrumented tetrapod was deployed to monitor boundary-layer processes controlling sediment transport. Coring devices recovered sediment to examine the benthic biological community, to measure rates of sedimentological processes, and to document sedimentary structure. During fair-weather conditions, the dominant mechanism for supplying sediment to Eckern-förde Bay is import from the Baltic Sea associated with internal waves. Earlier work has documented the erosion of shallow deposits during storms and the transport of this material to deeper sites in the Bay. Bottom shear stresses exerted in the Central Basin during all conditions are below critical stresses, which makes the Bay an excellent sediment trap. Sediment from both distant and local origins is reworked in the Central Basin of Eckernförde Bay by a pioneering community of benthic organisms, which is maintained by seasonal hypoxia/anoxia. The population is characterized by few species, small body sizes, young ages, and limited depth of mixing (˜1 cm). However, the community effectively pelletizes most of the sediment reaching the seabed. The very restricted thickness for the surface mixed layer (˜1 cm) and the substantial sediment accumulation rates (mean of 0.39 cm yr -1 for the Central Basin) give sediment a short exposure to modern oceanographic processes before being buried. These conditions allow for partial preservation of sediment deposited as storm layers, thus forming laminations of unpelletized sediment. These laminations separate thick beds of pelletized sediment deposited during fair weather or as thin storm layers (i.e., <1 cm thick). In general, the oceanographic processes in Eckernförde Bay allow for preservation of a high-resolution record of

  12. Geometric Series via Probability

    ERIC Educational Resources Information Center

    Tesman, Barry

    2012-01-01

    Infinite series is a challenging topic in the undergraduate mathematics curriculum for many students. In fact, there is a vast literature in mathematics education research on convergence issues. One of the most important types of infinite series is the geometric series. Their beauty lies in the fact that they can be evaluated explicitly and that…

  13. Alga-like forms in onverwacht series, South Africa: Oldest recognized lifelike forms on earth

    USGS Publications Warehouse

    Engel, A.E.J.; Nagy, B.; Nagy, L.A.; Engel, C.G.; Kremp, G.O.W.; Drew, C.M.

    1968-01-01

    Spheroidal and cupshaped, carbonaceous alga-like bodies, as well as filamentous structures and amorphous carbonaceous matter occur in sedimentary rocks of the Onverwacht Series (Swaziland System) in South Africa. The Onverwacht sediments are older than 3.2 eons, and they are probably the oldest, little-altered sedimentary rocks on Earth. The basal Onverwacht sediments lie approximutely 10,000 meters stratigraphically below the Fig Tree sedimentary rocks, from which similar organic microstructures have been interpreted as alga-like micro-fossils. The Onverwacht spheroids and filaments are best preserved in black, carbon-rich cherts and siliceous argillites interlayered with thick sequences of lavas. These lifelike forms and the associated carbonaceous substances are probably biological in origin. If so, the origins of unicellular life on Earth are buried in older rocks now obliterated by igneous and metamorphic events.

  14. Tectono-sedimentary architecture of Marie-Galante basin (Lesser Antilles fore arc)

    NASA Astrophysics Data System (ADS)

    Lebrun, Jean-Frédéric; Cornée, Jean-Jacques; Münch, Philippe; Guennoc, Pol

    2010-05-01

    Marie-Galante basin in the Lesser Antilles fore arc has experienced high amplitude (up to several thousand meters) vertical movements in response to both local tectonic in the fore-arc (trench perpendicular extensional tectonic) and geodynamical events at the plate interface, such as, long term interplate coupling changes, or ridges subduction or alternating period of under-platting/basal erosion... During the KaShallow cruises, we acquired ca. 3500km of high-resolution multichannel seismic reflection data (sparker and miniGI airgun sources), together with HR multibeam bathymetric (50m gridspacing DTM with ±2m depth precision) in the basin and over the shallow-water carbonate platforms surrounding the fore-arc islands. This geophysical dataset completes already existing seismic reflection data of lower resolution but deeper penetration. A systematic rock sampling using piston and rock corers and 2 ROV dives along remarkable cliffs, together with old dredge samples, provided petrological and sedimentary facies description, and datation (radiochronology and Micro/Nanno fossils) of the main stratigraphic series identified in seismic reflection through the basin. The basin divides into 3 sedimentary environments. We identify the architecture of the offshore carbonate platforms around the fore arc island and between them. Seismic profiles reveal the platforms prograding systems at their boundaries. This allows attempting a correlation between all the onshore/offshore archipelago platforms. Particularly, we evidence that the early Pleistocene upper series outcropping onshore extends offshore, and late Pleistocene/Holocene erosional surfaces are revealed. The "deep bassin", gently deepens southeastward from the volcanic arc islands of Basse-Terre and Dominica to the deep (5000m bsl) forearc basin at the accretionnary prism. Seismic profiles reveal the turbiditic infill of the basin. ROV dives permit to sample early Miocene pelagic sediments, and cores sample the late

  15. Vertical distribution of heavy metals in grain size fractions in sedimentary rocks: Mosina-Krajkowo water well field, Poland.

    PubMed

    Frankowski, M; Siepak, M; Zioła, A; Novotný, K; Vaculovic, T; Siepak, J

    2009-08-01

    The paper presents the results of heavy metals determination in samples of sedimentary rocks from the Mosina-Krajkowo water well field (Poland). The concentration of heavy metals was analysed by type of rock (sand, gravel, warp, silt, till, and clay). Variation of heavy metal concentrations with depth was studied taking into account the age series of the rocks (fluvial sediments of the modern Warta River valley, sediments of the Baltic Glaciation, tills of the Middle-Polish Glaciation, sediments of the Masovian Interglacial (Holstein), tills of the Poznań series) and granulometric fractions. The grain sizes considered included: >2.0, 2.0-1.0, 1.0-0.5, 0.5-0.25, 0.25-0.1, 0.1-0.063, and <0.063 mm. The concentrations of the heavy metals studied were found to change with the type of rock, age series, and granulometric fraction. The levels of the metals were determined by the technique of atomic absorption spectrometry with flame atomisation (F-AAS) and inductively coupled plasma-atomic emission spectrometry (ICP-AES).

  16. A Lower Rhine flood chronology based on the sedimentary record of an abandoned channel fill

    NASA Astrophysics Data System (ADS)

    Toonen, W. H. J.; Winkels, T. G.; Prins, M. A.; de Groot, L. V.; Bunnik, F. P. M.; Cohen, K. M.

    2012-04-01

    The Bienener Altrhein is an abandoned channel of the Lower Rhine (Germany). Following a late 16th century abandonment event, the channel was disconnected from the main stream and the oxbow lake gradually filled with 8 meters of flood deposits. This process still continues today. During annual floods, a limited proportion of overbank discharge is routed across the oxbow lake. Large floods produce individual flood layers, which are visually recognized in the sedimentary sequence. Based on the sedimentary characteristics of these event layers, we created a ~450-year flood chronology for the Lower Rhine. Laser-diffraction grain size measurements were used to assess relative flood magnitudes for individual flood event layers. Continuous sampling at a ~2 cm interval provided a high-resolution record, resolving the record at an annual scale. Standard descriptive techniques (e.g., mean grain size, 95th percentile, % sand) and the more advanced 'end member modelling' were applied to zoom in on the coarse particle bins in the grain size distributions, which are indicative of higher flow velocities. The most recent part of the record was equated to modern discharge measurements. This allows to establish relations between deposited grain size characteristics in the abandoned channel and flood magnitudes in the main river. This relation can also be applied on flood event layers from previous centuries, for which only water level measurements and historical descriptions exist. This makes this method relevant to expand data series used in flood frequency analysis from 100 years to more than 400 years. To date event-layers in the rapidly accumulated sequence, we created an age-depth model that uses organic content variations to tune sedimentation rates between the known basal and top ages. No suitable identifiable organic material for radiocarbon dating was found in the cores. Instead, palynological results (introduction of agricultural species) and palaeomagnetic secular

  17. Collaborative Research: Bringing Problem Solving in the Field into the Classroom: Developing and Assessing Virtual Field Trips for Teaching Sedimentary and Introductory Geology

    NASA Astrophysics Data System (ADS)

    Wang, P.; Caldwell, M.

    2012-12-01

    Coastal Florida offers a unique setting for the facilitation of learning about a variety of modern sedimentary environments. Despite the conflicting concept of "virtual" and "actual" field trip, and the uncertainties associated with the implementation and effectiveness, virtual trips provide likely the only way to reach a large diversified student population and eliminate travel time and expenses. In addition, with rapidly improving web and visualization technology, field trips can be simulated virtually. It is therefore essential to systematically develop and assess the educational effectiveness of virtual field trips. This project is developing, implementing, and assessing a series of virtual field trips for teaching undergraduate sedimentary geology at a large four-year research university and introductory geology at a large two-year community college. The virtual field trip is based on a four-day actual field trip for a senior level sedimentary geology class. Two versions of the virtual field trip, one for advanced class and one for introductory class, are being produced. The educational outcome of the virtual field trip will be compared to that from actual field trip. This presentation summarizes Year 1 achievements of the three-year project. The filming, editing, and initial production of the virtual field trip have been completed. Formative assessments were conducted by the Coalition for Science Literacy at the University of South Florida. Once tested and refined, the virtual field trips will be disseminated through broadly used web portals and workshops at regional and national meetings.

  18. Mechanisms for Fe(III) oxide reduction in sedimentary environments

    USGS Publications Warehouse

    Nevin, Kelly P.; Lovely, Derek R.

    2002-01-01

    Although it was previously considered that Fe(III)-reducing microorganisms must come into direct contact with Fe(III) oxides in order to reduce them, recent studies have suggested that electron-shuttling compounds and/or Fe(III) chelators, either naturally present or produced by the Fe(III)-reducing microorganisms themselves, may alleviate the need for the Fe(III) reducers to establish direct contact with Fe(III) oxides. Studies with Shewanella alga strain BrY and Fe(III) oxides sequestered within microporous beads demonstrated for the first time that this organism releases a compound(s) that permits electron transfer to Fe(III) oxides which the organism cannot directly contact. Furthermore, as much as 450 w M dissolved Fe(III) was detected in cultures of S. alga growing in Fe(III) oxide medium, suggesting that this organism releases compounds that can solublize Fe(III) from Fe(III) oxide. These results contrast with previous studies, which demonstrated that Geobacter metallireducens does not produce electron-shuttles or Fe(III) chelators. Some freshwater aquatic sediments and groundwaters contained compounds, which could act as electron shuttles by accepting electrons from G. metallireducens and then transferring the electrons to Fe(III). However, other samples lacked significant electron-shuttling capacity. Spectroscopic studies indicated that the electron-shuttling capacity of the waters was not only associated with the presence of humic substances, but water extracts of walnut, oak, and maple leaves contained electron-shuttling compounds did not appear to be humic substances. Porewater from a freshwater aquatic sediment and groundwater from a petroleum-contaminated aquifer contained dissolved Fe(III) (4-16 w M), suggesting that soluble Fe(III) may be available as an electron acceptor in some sedimentary environments. These results demonstrate that in order to accurately model the mechanisms for Fe(III) reduction in sedimentary environments it will be necessary

  19. Modern sedimentary environments in a large tidal estuary, Delaware Bay

    USGS Publications Warehouse

    Knebel, H. J.

    1989-01-01

    Data from an extensive grid of sidescan-sonar records reveal the distribution of sedimentary environments in the large, tidally dominated Delaware Bay estuary. Bathymetric features of the estuary include large tidal channels under the relatively deep (> 10 m water depth) central part of the bay, linear sand shoals (2-8 m relief) that parallel the sides of the tidal channels, and broad, low-relief plains that form the shallow bay margins. The two sedimentary environments that were identified are characterized by either (1) bedload transport and/or erosion or (2) sediment reworking and/or deposition. Sand waves and sand ribbons, composed of medium to coarse sands, define sites of active bedload transport within the tidal channels and in gaps between the linear shoals. The sand waves have spacings that vary from 1 to 70 m, amplitudes of 2 m or less, and crestlines that are usually straight. The orientations of the sand waves and ribbons indicate that bottom sediment movement may be toward either the northwest or southeast along the trends of the tidal channels, although sand-wave asymmetry indicates that the net bottom transport is directed northwestward toward the head of the bay. Gravelly, coarse-grained sediments, which appear as strongly reflective patterns on the sonographs, are also present along the axes and flanks of the tidal channels. These coarse sediments are lag deposits that have developed primarily where older strata were eroded at the bay floor. Conversely, fine sands that compose the linear shoals and muddy sands that cover the shallow bay margins appear mainly on the sonographs either as smooth featureless beds that have uniform light to moderate shading or as mosaics of light and dark patches produced by variations in grain size. These acoustic and textural characteristics are the result of sediment deposition and reworking. Data from this study (1) support the hypothesis that bed configurations under deep tidal flows are functions of current

  20. Origin of sedimentary organic matter at the Northern Cascadia Margin

    NASA Astrophysics Data System (ADS)

    Kaneko, M.; Naraoka, H.

    2007-12-01

    Gas hydrate in marine sediments may have important roles on global carbon cycle and climatic change. We examined origins of sedimentary organic matter and bacterial activity in deep and hydrate-bearing sediment cored in Site U1327 and U1328 at northern Cascadia Margin by IODP Exp311, using σ13C of total organic carbon (TOC), σ15N of total nitrogen (TN), σ34S of total sulfur (TS), and σ13C of biomarkers in hydrocarbon fraction. In both sites, TOC/TN ratios and σ13C of TOC values ranged from 5.5 to 18.0 and -25.7 to -21.5 ‰, respectively, suggesting that sedimentary organic matter is a mixture of terrestrial and marine sources. Long chain (n)-alkanes (C27, C29, and C30), known as biomarkers of terrestrial higher plant were most abundant components (up to ~50 μg/gCorg) through down to 300 mbsf, and their σ13C values (-34.3 to -28.7 ‰) reveal their C3 plant origin. In addition, very long-chain alkene (C37) occurred in some sediments, which suggests the blooming by coccolithophore in the past. σ34S of TS values at both sites show large variation between -30 to +20 ‰. Most of σ34S of TS values were less than present σ34S value of seawater sulfate (+20.3 ‰). This is attributable to isotope fractionation during microbial sulfate reduction. Crocetenes including one double bond occurred in deep sediments with higher σ13C values (-23 ‰) than the reported σ13C values (< ~ -100 ‰, Elvert et al, 2000), providing possibility of heterotrophic archaea using marine organic matter as a carbon source. Pentamethylicosane (PMI) was detected in relatively high concentrations at 249 mbsf at Site U1328 and its σ13C value was -46.4 ‰. This PMI could be chemoautotrophic archaea in origin such as methanogen. Diploptene was also detected in most sediments with the σ13C value of -37 to -35 ‰, probably being characteristic of chemoautotrophic bacteria.

  1. Inverse modeling of geochemical and mechanical compaction in sedimentary basins

    NASA Astrophysics Data System (ADS)

    Colombo, Ivo; Porta, Giovanni Michele; Guadagnini, Alberto

    2015-04-01

    We study key phenomena driving the feedback between sediment compaction processes and fluid flow in stratified sedimentary basins formed through lithification of sand and clay sediments after deposition. Processes we consider are mechanic compaction of the host rock and the geochemical compaction due to quartz cementation in sandstones. Key objectives of our study include (i) the quantification of the influence of the uncertainty of the model input parameters on the model output and (ii) the application of an inverse modeling technique to field scale data. Proper accounting of the feedback between sediment compaction processes and fluid flow in the subsurface is key to quantify a wide set of environmentally and industrially relevant phenomena. These include, e.g., compaction-driven brine and/or saltwater flow at deep locations and its influence on (a) tracer concentrations observed in shallow sediments, (b) build up of fluid overpressure, (c) hydrocarbon generation and migration, (d) subsidence due to groundwater and/or hydrocarbons withdrawal, and (e) formation of ore deposits. Main processes driving the diagenesis of sediments after deposition are mechanical compaction due to overburden and precipitation/dissolution associated with reactive transport. The natural evolution of sedimentary basins is characterized by geological time scales, thus preventing direct and exhaustive measurement of the system dynamical changes. The outputs of compaction models are plagued by uncertainty because of the incomplete knowledge of the models and parameters governing diagenesis. Development of robust methodologies for inverse modeling and parameter estimation under uncertainty is therefore crucial to the quantification of natural compaction phenomena. We employ a numerical methodology based on three building blocks: (i) space-time discretization of the compaction process; (ii) representation of target output variables through a Polynomial Chaos Expansion (PCE); and (iii) model

  2. Sedimentary basins reconnaissance using the magnetic Tilt-Depth method

    USGS Publications Warehouse

    Salem, A.; Williams, S.; Samson, E.; Fairhead, D.; Ravat, D.; Blakely, R.J.

    2010-01-01

    We compute the depth to the top of magnetic basement using the Tilt-Depth method from the best available magnetic anomaly grids covering the continental USA and Australia. For the USA, the Tilt-Depth estimates were compared with sediment thicknesses based on drilling data and show a correlation of 0.86 between the datasets. If random data were used then the correlation value goes to virtually zero. There is little to no lateral offset of the depth of basinal features although there is a tendency for the Tilt-Depth results to be slightly shallower than the drill depths. We also applied the Tilt-Depth method to a local-scale, relatively high-resolution aeromagnetic survey over the Olympic Peninsula of Washington State. The Tilt-Depth method successfully identified a variety of important tectonic elements known from geological mapping. Of particular interest, the Tilt-Depth method illuminated deep (3km) contacts within the non-magnetic sedimentary core of the Olympic Mountains, where magnetic anomalies are subdued and low in amplitude. For Australia, the Tilt-Depth estimates also give a good correlation with known areas of shallow basement and sedimentary basins. Our estimates of basement depth are not restricted to regional analysis but work equally well at the micro scale (basin scale) with depth estimates agreeing well with drill hole and seismic data. We focus on the eastern Officer Basin as an example of basin scale studies and find a good level of agreement between previously-derived basin models. However, our study potentially reveals depocentres not previously mapped due to the sparse distribution of well data. This example thus shows the potential additional advantage of the method in geological interpretation. The success of this study suggests that the Tilt-Depth method is useful in estimating the depth to crystalline basement when appropriate quality aeromagnetic anomaly data are used (i.e. line spacing on the order of or less than the expected depth to

  3. Glacially induced stresses in sedimentary rocks of northern Poland

    NASA Astrophysics Data System (ADS)

    Trzeciak, Maciej; Dąbrowski, Marcin

    2016-04-01

    During the Pleistocene large continental ice sheets developed in Scandinavia and North America. Ice-loading caused bending of the lithosphere and outward flow in the mantle. Glacial loading is one of the most prominent tectono-mechanical event in the geological history of northern Poland. The Pomeranian region was subjected several times to a load equivalent of more than 1 km of rocks, which led to severe increase in both vertical and horizontal stresses in the upper crustal rocks. During deglaciation a rapid decrease in vertical stress is observed, which leads to destabilization of the crust - most recent postglacial faults scarps in northern Sweden indicate glacially induced earthquakes of magnitude ~Mw8. The presence of the ice-sheet altered as well the near-surface thermal structure - thermal gradient inversion is still observable in NW Poland. The glacially related processes might have left an important mark in the sedimentary cover of northern Poland, especially with regard to fracture reopening, changes in stress state, and damage development. In the present study, we model lithospheric bending caused by glacial load, but our point of interest lies in the overlying sediments. Typical glacial isostatic studies model the response of (visco-) elastic lithosphere over viscoelastic or viscous asthenosphere subjected to external loads. In our model, we introduce viscoelastic sedimentary layers at the top of this stack and examine the stress relaxation patterns therein. As a case study for our modelling, we used geological profiles from northern Poland, near locality of Wejherowo, which are considered to have unconventional gas potential. The Paleozoic profile of this area is dominated by almost 1 km thick Silurian-Ordovician shale deposits, which are interbedded with thin and strong limestone layers. This sequence is underlain by Cambrian shales and sandstones, and finally at ~3 km depth - Precambrian crystalline rocks. Above the Silurian there are approximately

  4. Sedimentary Records of the Paleohurricane Activity in the Bahamas

    NASA Astrophysics Data System (ADS)

    Wallace, E. J.; Donnelly, J. P.; Wiman, C.; Cashman, M.

    2015-12-01

    Hurricanes pose a threat to human lives and can cause significant destruction of coastal areas. This threat has become more pronounced with recent rises in sea level and coastal populations. Currently, there is a large degree of uncertainty surrounding future changes in tropical cyclone activity. This is due to the limitations of climate models as well as the scarcity and unreliability of the current observational record. With so much uncertainty surrounding the current projections of hurricane activity, it is crucial to establish a longer and more accurate historical record. This study uses sediment cores extracted from blueholes in the Bahamas to develop a record of intense hurricane landfalls in the region dating back more than a millennia. The collected cores were sectioned, split, and scanned on an X-ray fluorescence scanner to obtain a high resolution core profile of the sediments' elemental composition and to identify potential sedimentary structures. Age control of the samples was determined using radiocarbon dating, coarse fraction was measured every centimeter, and hurricane event bed frequency was established for each core. We assess the statistical significance of the patterns observed in the sedimentary record using a coupled ocean-atmosphere hurricane model to simulate storms representative of modern climatology. Cores extracted from two blue holes near South Andros Island provide approximately a 1600 year and a 600 year record respectively, with sedimentation rates exceeding 1 cm/year. Both records contain coarse grained event deposits that correlate with known historical intense hurricane strikes in the Bahamas within age uncertainties. The 1600 year record confirms previous hurricane reconstructions from the Caribbean indicating higher tropical cyclone activity from 500 to 1400 CE. In addition, these new high-resolution records indicate elevated intense hurricane activity in the 17th and 18th centuries CE, when activity is also elevated in lower

  5. Processing of thermal parameters for the assessment of geothermal potential of sedimentary basins

    NASA Astrophysics Data System (ADS)

    Pasquale, V.; Chiozzi, P.; Gola, G.; Verdoya, M.

    2009-04-01

    having two or more temperature measurements at a single depth we selected 18 wells with BHTs recorded at te larger than 3.5 hours; the time span between two measurements varies from 1 to 21 hours. In total 71 couples of BHT-te data are available; the mud circulation time is lower or equal to 4.5 hours. Corrections require the knowledge of thermal parameters. We attempted to remedy the existing deficiency of thermal conductivity data of sedimentary rocks with a series of laboratory measurements on several core samples recovered from wells. Moreover, we developed a model for calculating the thermal conductivity of the rock matrix as a function of mineral composition based on the fabric theory and experimental thermal conductivity data. As the conductivity of clay minerals, which are present in most formations, is poorly defined, we applied an inverse approach, in which mineral conductivities are calculated one by one, on condition that the sample bulk thermal conductivity, the porosity and the amount of each mineral phase are known. Analyses show that formation equilibrium temperatures computed with the Horner method are consistent with those obtained by means of the Cooper and Jones method, which gives on average temperatures lower than 2 C only for shut-in times < 10 hours. The corrected temperatures compared with temperatures measured during drill-stem tests show that the proposed corrections are rather accurate. The two data sets give coherent results and the inferred average geothermal gradient is 21.5 mK/m in the Apenninic buried arc area and 25.2 mK/m in the South Piedmont Basin-Pedealpine homocline area. The problem with the Horner method is that it implicitly assumes no physical property contrast between circulating mud and formation, and that the borehole is infinitesimally thin, i.e. it acts as a line source. This has been criticized by many authors. The accuracy of the predicted temperatures depends on the reliability and accuracy of BHT, shut-in time and mud

  6. Sedimentary and upper crustal structure of Australia from receiver functions

    USGS Publications Warehouse

    Clitheroe, G.; Gudmundsson, O.; Kennett, B.L.N.

    2000-01-01

    The initial coda of teleseismic P-waves contains considerable information about the crust and upper mantle structure directly beneath a receiver. When this information can be recovered for a dense network of seismographs much can be learned about the structure of the earth. Data from the high quality broadband seismic stations of the SKIPPY and KIMBA projects along with permanent stations are used to investigate the upper crustal structure of Australia. A dataset of 65 shear-velocity models derived from receiver functions has enabled the sedimentary and upper crustal structure of Australia to be summarised. Regions of thick soft sediment show good agreement with topographical lows. A simple relation between upper-crustal velocity and magnetisation, as has been suggested by other investigators, has not been observed, but this may be due to the magnetic signal being muted by overlying sediments. A prominent mid-crustal discontinuity is apparent in the Tasman and New England mega-elements. This may represent a mid-crustal decollement that had structural control during accretion.

  7. Noise correlation tomography of Southwest Western Canada Sedimentary Basin

    NASA Astrophysics Data System (ADS)

    Gu, Yu Jeffrey; Shen, Luyi

    2015-07-01

    We analyse continuous recordings from 23 broadband seismic stations near Alberta, the southwestern sector of the Western Canada Sedimentary Basin. Noise correlation tomo-graphy based on vertical-component seismograms reveals below-average shear velocities at shallow and middle crustal depths in central Alberta, spanning across Proterozoic accreted terranes and Archean microcontinents. This observation likely results from extensive plate convergence and crustal melting during the Proterozoic eon. The overall correlation between the crustal velocities and presumed basement domains is lower than expected, however. In the lower crust, the main pattern of shear velocities is relatively concordant with the reported domain boundaries and key Precambrian structures appear to be intact. The shear velocities beneath the Loverna Block, the largest constituent of the Hearne craton, are 10 per cent higher than the regional average. This prominent northeast striking seismic anomaly is moderately correlated with the regional heat flow and potentially represents the remnant core of the Archean Hearne province. The associated high velocities extend into the western part of the Medicine Hat Block, a possible Archean microcontinent with a debatable origin, and contribute to a strong east-west structural gradient in the lower crust. The presence and the continuity of this anomalous structure imply extensive communications among the various basement domains in southern Alberta during the assembly of the North American continent.

  8. Antarctic Cenozoic climate history from sedimentary records: ANDRILL and beyond.

    PubMed

    McKay, R M; Barrett, P J; Levy, R S; Naish, T R; Golledge, N R; Pyne, A

    2016-01-28

    Mounting evidence from models and geological data implies that the Antarctic Ice Sheet may behave in an unstable manner and retreat rapidly in response to a warming climate, which is a key factor motivating efforts to improve estimates of Antarctic ice volume contributions to future sea-level rise. Here, we review Antarctic cooling history since peak temperatures of the Middle Eocene Climatic Optimum (approx. 50 Ma) to provide a framework for future initiatives to recover sediment cores from subglacial lakes and sedimentary basins in Antarctica's continental interior. While the existing inventory of cores has yielded important insights into the biotic and climatic evolution of Antarctica, strata have numerous and often lengthy time breaks, providing a framework of 'snapshots' through time. Further cores, and more work on existing cores, are needed to reconcile Antarctic records with the more continuous 'far-field' records documenting the evolution of global ice volume and deep-sea temperature. To achieve this, we argue for an integrated portfolio of drilling and coring missions that encompasses existing methodologies using ship- and sea-ice-/ice-shelf-based drilling platforms as well as recently developed seafloor-based drilling and subglacial access systems. We conclude by reviewing key technological issues that will need to be overcome.

  9. The potential for free and mixed convection in sedimentary basins

    USGS Publications Warehouse

    Raffensperger, J.P.; Vlassopoulos, D.

    1999-01-01

    Free thermal convection and mixed convection are considered as potential mechanisms for mass and heat transport in sedimentary basins. Mixed convection occurs when horizontal flows (forced convection) are superimposed on thermally driven flows. In cross section, mixed convection is characterized by convection cells that migrate laterally in the direction of forced convective flow. Two-dimensional finite-element simulations of variable-density groundwater flow and heat transport in a horizontal porous layer were performed to determine critical mean Rayleigh numbers for the onset of free convection, using both isothermal and semi-conductive boundaries. Additional simulations imposed a varying lateral fluid flux on the free-convection pattern. Results from these experiments indicate that forced convection becomes dominant, completely eliminating buoyancy-driven circulation, when the total forced-convection fluid flux exceeds the total flux possible due to free convection. Calculations of the thermal rock alteration index (RAI=q????T) delineate the patterns of potential diagenesis produced by fluid movement through temperature gradients. Free convection produces a distinct pattern of alternating positive and negative RAIs, whereas mixed convection produces a simpler layering of positive and negative values and in general less diagenetic alteration. ?? Springer-Verlag.

  10. The shapes of cold, high mountains in sedimentary rocks

    NASA Astrophysics Data System (ADS)

    Cruden, D. M.

    2003-09-01

    Terzaghi (Geotechnique 12 (1962) 251) and Young (Young, A., 1972. Slopes. Oliver and Boyd, Edinburgh, 288 pp.) described the stable forms of slopes in sedimentary rock masses, assuming penetrative discontinuities, which are parallel to bedding and joints which are perpendicular to bedding. The only movements considered were slides along bedding. Experience in the Canadian Rockies indicates that the cohesionless rock masses that exist at or above tree line may also move by toppling, buckling and sliding along joints. These processes also act to limit the inclinations of stable slopes. Rock strength is a factor in the critical height of a slope that buckles. The processes can be represented as fields on a process diagram, a plot of slope inclination against bedding dip, using the basic friction angles of the rocks present. The process diagram also separates five common mountain peak shapes, which form on homoclinal sequences of beds. Castellate and Matterhorn mountains occur in sub-horizontal beds, cuestas develop in gently to moderately dipping beds. Hogbacks formed in moderately to steeply dipping beds have similar slope angles on both cataclinal and anaclinal slopes. Dogtooth mountains occur in steeply dipping sub-vertical beds.

  11. Reconstruction of Sedimentary Rock Based on MechanicalProperties

    SciTech Connect

    Jin, Guodong; Patzek, Tad W.; Silin, Dmitry B.

    2004-05-04

    We describe a general, physics-based approach to numericalreconstruction of the geometrical structure and mechanical properties ofnatural sedimentary rock in 3D. Our procedure consists of three mainsteps: sedimentation, compaction, and diagenesis, followed by theverification of rock mechanical properties. The dynamic geologicprocesses of grain sedimentation and compaction are simulated by solvinga dimensionless form of Newton's equations of motion for an ensemble ofgrains. The diagenetic rock transformation is modeled using a cementationalgorithm, which accounts for the effect of rock grain size on therelative rate of cement overgrowth. Our emphasis is on unconsolidatedsand and sandstone. The main input parameters are the grain sizedistribution, the final rock porosity, the type and amount of cement andclay minerals, and grain mechanical properties: the inter-grain frictioncoefficient, the cement strength, and the grain stiffness moduli. We usea simulated 2D Fontainebleau sandstone to obtain the grain mechanicalproperties. This Fontainebleau sandstone is also used to study theinitiation, growth, and coalescence of micro-cracks under increasingvertical stress. The box fractal dimension of the micro-crackdistribution, and its variation with the applied stress areestimated.

  12. Late Cenozoic sedimentary and tectonic history of south Buton, Indonesia

    NASA Astrophysics Data System (ADS)

    Fortuin, A. R.; De Smet, M. E. M.; Hadiwasastra, S.; Van Marle, L. J.; Troelstra, S. R.; Tjokrosapoetro, S.

    A description and interpretation are given of the Upper Cenozoic sedimentary record of south Buton. Various sections and outcrops were studied and sampled for their microfossil content, to provide age and paleobathymetrical data. Together with information from the literature, these data from the base for a geohistory analysis to evaluate the vertical motions. Deposition started some 11 Ma ago, after the main deformation of the island, which was related to the collision of a microplate carrying Buton, with the southeast arm of Sulawesi. Coarse and fine terrigenous debris accumulated in a rapidly subsiding foreland basin; subsidence may have exceeded 100 cm/ka. When the rate of subsidence decreased a late Miocene-early Pliocene period of quiet pelagic sedimentation followed. From the late Pliocene onwards (around 3.5 Ma BP) an overall uplift took place, with rates between 30-120 cm/ka. This drastic change is explained by the collision of Buton with a submerged microcontinent that presently forms the Tukang Besi platform, situated southeast of Buton, which interaction resulted in wrench type tectonics and a clockwise rotation of over 60° for south Buton.

  13. Organic geochemical analysis of sedimentary organic matter associated with uranium

    USGS Publications Warehouse

    Leventhal, J.S.; Daws, T.A.; Frye, J.S.

    1986-01-01

    Samples of sedimentary organic matter from several geologic environments and ages which are enriched in uranium (56 ppm to 12%) have been characterized. The three analytical techniqyes used to study the samples were Rock-Eval pyrolysis, pyrolysis-gas chromatography-mass spectrometry, and solid-state C-13 nuclear magnetic resonance (NMR) spectroscopy. In samples with low uranium content, the pyrolysis-gas chromatography products contain oxygenated functional groups (as hydroxyl) and molecules with both aliphatic and aromatic carbon atoms. These samples with low uranium content give measurable Rock-Eval hydrocarbon and organic-CO2 yields, and C-13 NMR values of > 30% aliphatic carbon. In contrast, uranium-rich samples have few hydrocarbon pyrolysis products, increased Rock-Eval organic-CO2 contents and > 70% aromatic carbon contents from C-13 NMR. The increase in aromaticity and decrease in hydrocarbon pyrolysis yield are related to the amount of uranium and the age of the uranium minerals, which correspond to the degree of radiation damage. The three analytical techniques give complementary results. Increase in Rock-Eval organic-CO2 yield correlates with uranium content for samples from the Grants uranium region. Calculations show that the amount of organic-CO2 corresponds to the quantity of uranium chemically reduced by the organic matter for the Grants uranium region samples. ?? 1986.

  14. Combining electromagnetic measurements in the Mygdonian sedimentary basin, Greece

    NASA Astrophysics Data System (ADS)

    Autio, U.; Smirnov, M. Yu.; Savvaidis, A.; Soupios, P.; Bastani, M.

    2016-12-01

    We present a novel approach where time-domain electromagnetic (TEM) data are transformed and subsequently used in two-dimensional (2-D) magnetotelluric inversion of the determinant of the impedance tensor. The main idea is to integrate TEM with magnetotelluric (MT) data to produce subsurface electrical resistivity models. Specifically, we show that 2-D MT data inversion of the determinant of the impedance tensor supported by inclusion of TEM-MT-transformed data has superior resolution at the near surface and at the same time static shift afflicting the MT data can be addressed. Thus, the approach allows for practical express integration of TEM data with MT measurements as opposed to a full combined 3-D inversion, which requires significant resources. The approach is successfully applied in the Mygdonian sedimentary basin located in Northern Greece. In addition to TEM and MT data, also controlled source - and radiomagnetotelluric data are available from the Mygdonian basin, which have been subjected to 2-D analysis previously. We have extended the analysis to a full 3-D inversion using ModEM code. All obtained models are analysed and are in a good agreement.

  15. Distribution and thickness of sedimentary facies in the coastal dune, beach and nearshore sedimentary system at Maspalomas, Canary Islands

    NASA Astrophysics Data System (ADS)

    Fontán Bouzas, Angela; Alcántara-Carrió, Javier; Montoya Montes, Isabel; Barranco Ojeda, Andrés; Albarracín, Silvia; Rey Díaz de Rada, Jorge; Rey Salgado, Jorge

    2013-04-01

    Numerous studies have shown that most beaches and coastal dune systems of the world are currently eroding but very few have investigated the combined sediment budgets of subaerial and nearshore submarine systems. In the case of the dune field of the Maspalomas Natural Special Reserve (in the south of Gran Canaria), the adjacent Maspalomas and El Inglés beaches and the adjacent submarine platform, the sediment budgets have been severely affected by erosion over the past few decades. The objectives of this study were to investigate the availability of sand within the modern sedimentary system, including the coastal dunes, the beaches and the submerged shelf, but also to assess local sediment sinks. An isopach map generated on the basis of topo-bathymetric data and seismic-reflection profiles revealed that sediment thickness varies from 0-22 m in the study area. Expanses of relatively low sediment thickness were identified in the south-western sector of the coastal dune field along Maspalomas beach, and in the nearshore region to the south of this beach. These localized sediment-deficit areas earmark Maspalomas beach as the most vulnerable shore strip threatened by erosion. The shallow seismic data also revealed that the submarine platform south of Maspalomas represents a marine terrace cut into an ancient alluvial fan, thus documenting an influence of the geomorphological heritage on the present-day morphodynamics. A side-scan sonar mosaic of this nearshore platform enabled the delimitation of areas covered by rock, boulders and gravel, vegetated sand patches and a mobile sand facies, the latter including ripple and megaripple fields. The megaripple field in a valley close to the talus of the marine terrace has been identified as a major sediment sink of the Maspalomas sedimentary system. It is fed by south-westerly storm-wave events. The sediment deficit in the coastal dune field and along Maspalomas beach can therefore only be explained by a currently faster loss

  16. SHRIMP uranium-lead dating of diagenetic xenotime in siliciclastic sedimentary rocks

    PubMed

    McNaughton; Rasmussen; Fletcher

    1999-07-02

    Diagenetic xenotime is common in siliciclastic sedimentary rocks, where it starts to form on detrital zircon shortly after sediment deposition. It is possible to estimate the age of sedimentary rocks by in situ uranium-lead analysis of that xenotime. Two Proterozoic sandstone units from northwestern Australia, previously constrained to the age interval of 1790 to 750 million years ago, have diagenetic xenotime ages of 1704 +/- 7 and 1704 +/- 14 million years ago. This method has potential for dating sedimentary sequences of all ages but should be especially valuable for refining the Precambrian time scale.

  17. Sedimentary textures formed by aqueous processes, Erebus crater Meridiani Planum, Mars

    USGS Publications Warehouse

    Grotzinger, J.; Bell, J.; Herkenhoff, K.; Johnson, J.; Knoll, A.; McCartney, E.; McLennan, S.; Metz, J.; Moore, J.; Squyres, S.; Sullivan, R.; Ahronson, O.; Arvidson, R.; Joliff, B.; Golombek, M.; Lewis, K.; Parker, T.; Soderblom, J.

    2006-01-01

    New observations at Erebus crater (Olympia outcrop) by the Mars Exploration Rover Opportunity between sols 671 and 735 (a sol is a martian day) indicate that a diverse suite of primary and penecontemporaneous sedimentary structures is preserved in sulfate-rich bedrock. Centimeter-scale trough (festoon) cross-lamination is abundant, and is better expressed and thicker than previously described examples. Postdepositional shrinkage cracks in the same outcrop are interpreted to have formed in response to desiccation. Considered collectively, this suite of sedimentary structures provides strong support for the involvement of liquid water during accumulation of sedimentary rocks at Meridiani Planum. ?? 2006 Geological Society of America.

  18. Series Transmission Line Transformer

    DOEpatents

    Buckles, Robert A.; Booth, Rex; Yen, Boris T.

    2004-06-29

    A series transmission line transformer is set forth which includes two or more of impedance matched sets of at least two transmissions lines such as shielded cables, connected in parallel at one end ans series at the other in a cascading fashion. The cables are wound about a magnetic core. The series transmission line transformer (STLT) which can provide for higher impedance ratios and bandwidths, which is scalable, and which is of simpler design and construction.

  19. Fourier Series Operating Package

    NASA Technical Reports Server (NTRS)

    Charnow, Milton L.

    1961-01-01

    This report presents a computer program for multiplying, adding, differentiating, integrating, "barring" and scalarly multiplying "literal" Fourier series as such, and for extracting the coefficients of specified terms.

  20. Cenozoic uplift on the West Greenland margin: active sedimentary basins in quiet Archean terranes.

    NASA Astrophysics Data System (ADS)

    Jess, Scott; Stephenson, Randell; Brown, Roderick

    2016-04-01

    The North Atlantic is believed by some authors to have experienced tectonically induced uplift within the Cenozoic. Examination of evidence, onshore and offshore, has been interpreted to imply the presence of kilometre scale uplift across the margins of the Barents Sea, North Sea, Baffin Bay and Greenland Sea. Development of topography on the West Greenland margin (Baffin Bay), in particular, has been subject to much discussion and dispute. A series of low temperature thermochronological (AFT and AHe) studies onshore and interpretation of seismic architecture offshore have suggested uplift of the entire margin totalling ~3km. However, challenges to this work and recent analysis on the opposing margin (Baffin Island) have raised questions about the validity of this interpretation. The present work reviews and remodels the thermochronological data from onshore West Greenland with the aim of re-evaluating our understanding of the margin's history. New concepts within the discipline, such as effect of radiation damage on Helium diffusivity, contemporary modelling approaches and denudational mapping are all utilised to investigate alternative interpretations to this margins complex post rift evolution. In contrast to earlier studies our new approach indicates slow protracted cooling across much of the region; however, reworked sedimentary samples taken from the Cretaceous Nuussuaq Basin display periods of rapid reheating and cooling. These new models suggest the Nuussuaq Basin experienced a tectonically active Cenozoic, while the surrounding Archean basement remained quiet. Faults located within the basin appear to have been reactivated during the Palaeocene and Eocene, a period of well-documented inversion events throughout the North Atlantic, and may have resulted in subaerial kilometre scale uplift. This interpretation of the margin's evolution has wider implications for the treatment of low temperature thermochronological data and the geological history of the North

  1. 1.8 Billion Years of Detrital Zircon Recycling Calibrates a Refractory Part of Earth's Sedimentary Cycle.

    PubMed

    Hadlari, Thomas; Swindles, Graeme T; Galloway, Jennifer M; Bell, Kimberley M; Sulphur, Kyle C; Heaman, Larry M; Beranek, Luke P; Fallas, Karen M

    2015-01-01

    Detrital zircon studies are providing new insights on the evolution of sedimentary basins but the role of sedimentary recycling remains largely undefined. In a broad region of northwestern North America, this contribution traces the pathway of detrital zircon sand grains from Proterozoic sandstones through Phanerozoic strata and argues for multi-stage sedimentary recycling over more than a billion years. As a test of our hypothesis, integrated palynology and detrital zircon provenance provides clear evidence for erosion of Carboniferous strata in the northern Cordillera as a sediment source for Upper Cretaceous strata. Our results help to calibrate Earth's sedimentary cycle by showing that recycling dominates sedimentary provenance for the refractory mineral zircon.

  2. Reconstruction of in situ composition of sedimentary formation waters

    NASA Astrophysics Data System (ADS)

    Palandri, James L.; Reed, Mark H.

    2001-06-01

    Chemical equilibrium calculations on sedimentary formation waters show that the waters, as analyzed, cannot be in equilibrium with diagenetic minerals in their host rocks at the formation temperature. However, if alkalinity is corrected to account for organic acid anions, and if the pH and bicarbonate are corrected for CO 2 loss from the sample, chemical equilibrium between formation waters and host rock diagenetic minerals can be clearly shown for systems in the temperature range of 75 to 160°C. Compositional reconstruction of some formation waters from published analyses is complicated by lack of analytical data for aluminum, silica, and organic acid anions. Missing aluminum and silica can be estimated by assuming equilibrium with an aluminum silicate (K-feldspar, muscovite) and quartz or chalcedony. pH, CO 2, and organic acid anions can be reconstructed by fixing CO 2 to exactly saturate calcite at the formation temperature because the fast kinetics of calcite precipitation makes it almost certain that calcite saturation is more likely than the strong supersaturation that is otherwise observed. Results from the equilibrium calculations are evaluated by using graphs of the saturation states of diagenetic minerals vs. temperature, for each of many sedimentary brines. If the diagenetic minerals selected as diagnostic of equilibrium (from qz, chalcedony, mus, paragonite, k-sp, alb, kaol, ca, and dol) are not saturated at or near a single temperature, the missing or erroneous quantities of components are adjusted to obtain agreement in the saturation temperature. Composition data for fluids from four locations are used in the calculations: Kettleman North Dome, California, offshore Norway, the Texas Gulf Coast, and offshore Texas. The calculations suggest that in most cases, control of silica concentration shifts from chalcedony to quartz with increasing temperature near 100°C. In some fluids, silica concentration may approach chalcedony saturation to temperatures

  3. Feasibility study of sedimentary enhanced geothermal systems using reservoir simulation

    NASA Astrophysics Data System (ADS)

    Cho, Jae Kyoung

    The objective of this research is to evaluate the preliminary feasibility of commercial geothermal projects, from a sedimentary reservoir with low permeability that requires productivity enhancement, using numerical reservoir simulation. The performance of a sedimentary geothermal reservoir is investigated in terms of reservoir hydraulics and thermal evolution. To build a reliable benchmark for simulation study, validation of the numerical reservoir model with respect to an analytical model is presented, and the process to achieve an acceptable match between the numerical and analytical solutions is described. The analytical model used in this study is based on the work of Gringarten (1978), which consists of a conceptual geothermal reservoir, considering an injection and production well doublet in a homogeneous porous media. A commercial thermal reservoir simulator (STARS from Computer Modeling Group, CMG) is used in this work for numerical modeling. In order to reproduce the analytical model results, the numerical simulation model is modified to include the same assumptions of the analytical model. Simulation model parameters that make the numerical results deviate from the analytical solution, such as the grid block size, time step and no-flow boundary are identified and investigated. An analytical tracer test model proposed by Shook (2000) is numerically modeled. This model allows us to predict the time when the temperature of the produced water decreases by capturing a tracer component at production well. Reservoir simulation models with different porosity and permeability distribution are tested to see the effects of reservoir inhomogeneity and anisotropy. In particular, premature thermal breakthrough due to the presence of high permeability streak in a reservoir model is simulated. In an effort to apply the knowledge we obtained from the analytical solutions, the effects of reservoir rock and water properties, as a function of pressure and temperature, are

  4. A Sedimentary Carbon Inventory for a Scottish Sea Loch

    NASA Astrophysics Data System (ADS)

    Smeaton, Craig; Austin, William; Davies, Althea; Baltzer, Agnes

    2015-04-01

    Coastal oceans are sites of biogeochemical cycling, as terrestrial, atmospheric, and marine carbon cycles interact. Important processes that affect the carbon cycle in the coastal ocean include upwelling, river input, air-sea gas exchange, primary production, respiration, sediment burial, export, and sea-ice dynamics. The magnitude and variability of many carbon fluxes are accordingly much higher in coastal oceans than in open ocean environments. Having high-quality observations of carbon stocks and fluxes in the coastal environment is important both for understanding coastal ocean carbon balance and for reconciling continent-scale carbon budgets. Despite the ecological, biological, and economic importance of coastal oceans, the magnitude and variability of many of the coastal carbon stocks are poorly quantified in most regions in comparison to terrestrial and deep ocean carbon stocks. The first stage in understanding the carbon dynamics in coastal waters is to quantify the existing carbon stocks. The coastal sediment potentially holds a significant volume of carbon; yet there has been no comprehensive attempt to quantitatively determine the volume of carbon held in those coastal sediments as echoed by Bauer et al., (2013) "the diverse sources and sinks of carbon and their complex interactions in these waters remain poorly understood". We set out to create the first sedimentary carbon inventory for a sea loch (fjord); through a combination of geophysics and biogeochemistry. Two key questions must be answered to achieve this goal; how much sediment is held within the loch and what percentage of that sediment carbon? The restrictive geomorphology of sea lochs (fjords) provides the perfect area to develop this methodology and answer these fundamental questions. Loch Sunart the longest of the Scottish sea lochs is our initial test site due to existing geophysical data being available for analysis. Here we discuss the development of the joint geophysics and

  5. Geochemistry of sedimentary-derived migmatite from NE Sardinia, Italy

    NASA Astrophysics Data System (ADS)

    Cruciani, Gabriele; Fancello, Dario; Franceschelli, Marcello; Scodina, Massimo

    2015-04-01

    In NE Sardinia at Porto Ottiolu, about 30 km south of Olbia (NE Sardinia), crops out a sequence of migmatized ortho and paragneiss, belonging to the Variscan basement's axial zone. Sedimentary-derived migmatite, which have a layered appearance in the field, were affected by three major variscan folding phase. D2, which is characterized by tight folds, is the most widespread deformation in the field. Leucosomes consists of discontinuous centimetre-thick, coarse-grained layers, that follow the S2 schistosity and are folded by D2 deformation phase. The contact with mesosome is sharp and sometimes marked by melanosome trails. They consist of quartz, plagioclase, very rare K-feldspar, muscovite, biotite, fibrolite, and rare kyanite. Plagioclase is unzoned oligoclase, though in some cases a thin albite rim is observed. Muscovite occurs as: i) single small- to medium-grained flakes enclosed in feldspar; ii) coarse grained crystals associated to biotite, fibrolite, and opaques, iii) in intergrowth with biotite to form thin elongated, slightly oriented trails, marking the faint foliation. Mesosomes are medium-grained, well foliated rocks, consisting of quartz, plagioclase muscovite, , biotite, fibrolite ± K-feldspar ± garnet. Fibrolite, muscovite and biotite are associated, to form strongly oriented, thick levels. Muscovite also occurs as unoriented crystals, showing quartz exsolutions and thin rims. A few mm-thick melanosome is usually present at the boundary between the leucosomes and mesosomes. Leucosomes are characterized by: SiO2: 75.4-77.9; Al2O3: 13.2-14.5; Fe2O3tot: 0.3-0.5; MgO: 0.1-0.2; CaO: 2.7- 3.7; Na2O: 3.9-4.6; K2O: 0.4-0.6 wt.%. An interesting feature is the relative high calcium content already described in other sedimentary-derived migmatite from Sardinia (Cruciani et al., 2008). In the normative Ab-An-Or diagram (Barker, 1979) the leucosomes plot at the boundary between trondhjemite/tonalite fields. All leucosomes are corundum normative and peraluminous

  6. Western Tibet relief evolution, insight from sedimentary record and thermochronology

    NASA Astrophysics Data System (ADS)

    Mahéo, Gweltaz; Gourbet, Loraine; Hervé Leloup, Philippe; Sorrel, Philippe; Shuster, David L.; Paquette, Jean-Louis; Quillévéré, Frédéric

    2014-05-01

    The Tibetan plateau is defined as a low relief high elevation zone, resulting from India-Asia convergence. However, its morphology is relatively heterogeneous. Especially the western Tibetan plateau is characterized by a strong relief, numerous peaks higher than 6000 m.a.s.l. and large (up to 10 km), deep (1-2 km) valleys. We investigate the origin of this particular morphology, coupling geomorphologic studies with sedimentary records and (U-Th)/He thermochronometry. The western Tibet Tertiary sedimentation is mostly characterized by conglomerates, red sandstone and siltstones related with alluvial fan deposits. Zircon U-Pb dating of interbedded trachyte flows implies that deposition started before 25 Ma and was still ongoing at 20 Ma. These continental, detrital deposits are filling wide open valleys during probable arid climatic conditions. Such valleys are thus interpreted as inherited basins, paleovalleys, formed before detrital sedimentation i.e. at ~25 Ma. Moreover, rare marine sediments were observed below the detrital deposits. Foraminifera suggest an Oligocene age, which implies that the paleovalleys already existed during the Oligocene, and that the emersion of the Western Tibetan Plateau occurred between the Oligocene and 25 Ma. This emersion thus occurred much later than the India-Asia collision (~50-45Ma) but is compatible with the onset of the main thickening phase of the Indian plate. The orientation of the inherited valley axis appears to be that of active strike slip faults that induced eastward extrusion of Western Tibet. This suggests that such extrusion was already active at the time of sedimentation (both marine and continental). Thus extrusion was also active during the plateau emersion at Oligocene time. The morphology of the valleys, and their sedimentary infilling, suggest that a significant relief, similar to present-day one (about 1000-2000m between valleys floor and surrounding peaks) already existed at the time of sedimentation. This

  7. Long-term sedimentary recycling of rare sulphur isotope anomalies.

    PubMed

    Reinhard, Christopher T; Planavsky, Noah J; Lyons, Timothy W

    2013-05-02

    The accumulation of substantial quantities of O2 in the atmosphere has come to control the chemistry and ecological structure of Earth's surface. Non-mass-dependent (NMD) sulphur isotope anomalies in the rock record are the central tool used to reconstruct the redox history of the early atmosphere. The generation and initial delivery of these anomalies to marine sediments requires low partial pressures of atmospheric O2 (p(O2); refs 2, 3), and the disappearance of NMD anomalies from the rock record 2.32 billion years ago is thought to have signalled a departure from persistently low atmospheric oxygen levels (less than about 10(-5) times the present atmospheric level) during approximately the first two billion years of Earth's history. Here we present a model study designed to describe the long-term surface recycling of crustal NMD anomalies, and show that the record of this geochemical signal is likely to display a 'crustal memory effect' following increases in atmospheric p(O2) above this threshold. Once NMD anomalies have been buried in the upper crust they are extremely resistant to removal, and can be erased only through successive cycles of weathering, dilution and burial on an oxygenated Earth surface. This recycling results in the residual incorporation of NMD anomalies into the sedimentary record long after synchronous atmospheric generation of the isotopic signal has ceased, with dynamic and measurable signals probably surviving for as long as 10-100 million years subsequent to an increase in atmospheric p(O2) to more than 10(-5) times the present atmospheric level. Our results can reconcile geochemical evidence for oxygen production and transient accumulation with the maintenance of NMD anomalies on the early Earth, and suggest that future work should investigate the notion that temporally continuous generation of new NMD sulphur isotope anomalies in the atmosphere was likely to have ceased long before their ultimate disappearance from the rock record.

  8. Sedimentary basin framework of Exmouth Plateau, northwest Australia

    SciTech Connect

    Boyd, R.; Exon, N.; Williamson, P.

    1987-05-01

    The Exmouth Plateau is a marginal plateau lying off northwest Australia. Water depths range between 800 m and 4000 m, and the area shallower than 2000 m covers approximately 150,000 km/sup 2/. The plateau consists of rifted and deeply subsided continental crust, with a Phanerozoic sedimentary sequence around 10 km thick, deposited in the Canning and Carnarvon basins. The plateau is separated from the Northwest Shelf by the Kangaroo syncline and is bounded to the north, west, and south by oceanic crust of Cretaceous and Jurassic age. The present structural configuration of Exmouth Plateau was initiated by rifting in the Triassic to Middle Jurassic, followed by northwest-oriented sea floor spreading. The western margin has a normal rifted structure, while the southern margin structure was dominated by transform motion. The complex rifted and sheared northern margin contains at least one crustal block of post-breakup igneous origin. Below a rift onset unconformity of Neocomian age lies a thick Triassic paralic sequence to the south, while farther north the unconformity is of Callovian age and overlies a Jurassic sequence of Tethyan carbonates, coal measures, and volcanics. The post-breakup sequence consists of Late Jurassic-Cenomanian deltaic and shelf clastics, overlain by thin Late Cretaceous-Tertiary shallow marine to pelagic carbonates. Exmouth Plateau therefore represents classic rift to mature ocean stage development of a sediment-starved passive margin. The large fault blocks in the rifted Triassic-Jurassic sequences and large areal closures in the Cretaceous deltas encouraged petroleum exploration over the last two decades. The rifted section was shown to be gas prone, while the overlying section proved to be largely immature.

  9. Biogenic syngenetic pyrite from tuffaceous sedimentary RF3-V rocks

    NASA Astrophysics Data System (ADS)

    Kozyreva, Irina; Nikulova, Natalia

    2015-04-01

    Biogenic framboidal pyrite was found in intraformational tuffaceous sedimentary gravelites, within basic volcanites (RF3-V) in Subpolar Urals (Sablya Ridge). Pyrite grains (Fe 44.07-44,33, S 50.22-53.31 wt. %) are composed of ball-like microconcretions, sometimes intergrown with crystals of pentagondodecahedron and cubic habit. The microconcretions (20 to 40 mcm) are roundish and composed of microcrystals, which end faces form spherical surface. The nuclei of the microconcretions are represented by frambohedrons 4-5 mcm in size, which are pyritized cells of sulphate-reducing colonial coccoid microfossils. The formation of the frambohedrons occurred synchronously to sedimentation in stagnant reducing environment at interaction of biogenic hydrogen sulphide with water-dissolved iron. The biogenic hydrogen sulphide is reduced by microorganisms in the conditions of free and unrestricted access of dissolved sulphate ions sourced from sulphur of fumarole gases. Iron came from washed-out basic volcanites. The growth of outer radial parts of microconcretions occurred during compaction of sediments in diagenetic stage. The quantity of dissolved sulphate and iron during pyrite formation exceeded possibilitites of bacterial "starters" which resulted in the formation of pyrites of other morphological varieties. This is confirmed by the accretion of concentric rays of the concretions and cubic microcrystals of pyrite in the aggregate grains. The formation of tuffaceous sediments occurred during temporary decrease of volcanic activity in a continuous linear water flow with stagnant areas composed of water-displaced pebbles from underlying metaterrigenous rocks (RF 1-2), which were exposed beyond the development area of volcanic strata, unchanged clasts of recent and synchronously formed basic and medium volcanites with participation of air-driven ashes and influence of volcanic gases in the presence of sulphate-reducing bacteria. The work is financially supported by the Program

  10. Rapid imbibition of water in fractures within unsaturated sedimentary rock

    DOE PAGES

    Cheng, Chu-Lin; Perfect, Edmund; Donnelly, B.; ...

    2015-01-27

    The spontaneous imbibition of water and other liquids into gas-filled fractures in variably-saturated porous media is important in a variety of engineering and geological contexts. However, surprisingly few studies have investigated this phenomenon. In this paper, we present a theoretical framework for predicting the 1-dimensional movement of water into air-filled fractures within a porous medium based on early-time capillary dynamics and spreading over the rough surfaces of fracture faces. The theory permits estimation of sorptivity values for the matrix and fracture zone, as well as a dispersion parameter which quantifies the extent of spreading of the wetting front. Quantitative datamore » on spontaneous imbibition of water in unsaturated Berea sandstone cores were acquired to evaluate the proposed model. The cores with different permeability classes ranging from 50 to 500 mD and were fractured using the Brazilian method. Spontaneous imbibition in the fractured cores was measured by dynamic neutron radiography at the Neutron Imaging Prototype Facility (beam line CG-1D, HFIR), Oak Ridge National Laboratory. Water uptake into both the matrix and the fracture zone exhibited square-root-of-time behavior. The matrix sorptivities ranged from 2.9 to 4.6 mm s-0.5, and increased linearly as the permeability class increased. The sorptivities of the fracture zones ranged from 17.9 to 27.1 mm s-0.5, and increased linearly with increasing fracture aperture width. The dispersion coefficients ranged from 23.7 to 66.7 mm2 s-1 and increased linearly with increasing fracture aperture width and damage zone width. Both theory and observations indicate that fractures can significantly increase spontaneous imbibition in unsaturated sedimentary rock by capillary action and surface spreading on rough fracture faces. Fractures also increase the dispersion of the wetting front. In conclusion, further research is needed to investigate this phenomenon in other natural and engineered

  11. M7+ Virtual Earthquakes near Kanto Sedimentary Basin

    NASA Astrophysics Data System (ADS)

    Denolle, M.; Boué, P.; Hirata, N.; Nakagawa, S.; Miyake, H.; Beroza, G. C.

    2015-12-01

    The Tokyo Metropolitan area is subject to high earthquake activity due to its location near the complex junction of three plates. The seismic hazard Tokyo faces is amplified because it lies in the Kanto basin. The Itoigawa-Shizuoka Tectonic Line (ISTL) is one of the crustal fault zones that comprise these plate boundaries. The ISTL accommodates plate motion between the North American Plate and the Eurasian Plate, hosts oblique-strike slip earthquakes with magnitudes greater than 7, and is only ~ 150-200km away from Tokyo. It is thought to be at a mature stage in its seismic cycle, and predicting strong ground motion from earthquakes on it is important for seismic hazard assessment. We take advantage of the dense seismic network MeSO-net (MEtropolitan Seismic Observation network) and of the locations of the Hi-net (High Sensitivity Seismograph network) stations near the ISTL fault to build virtual earthquakes from the ambient seismic field. First, we construct the Earth's impulse responses from deconvolution of the ambient seismic field recorded between Hi-net stations (as sources) and MeSO-net stations (as receivers) with a method that preserves the relative amplitudes of the response. Fundamental and higher modes are often excited in sedimentary basins and we isolate them in the waveforms through phase velocity analysis in the frequency-wavenumber domain. The virtual earthquake approach turns each station-source near the fault into a double-couple point source by correcting the 9-component impulse response for source depth and mechanism. We use recordings of the M6.7 Northern Nagano earthquake that occurred on November 22, 2014 at the northern end of the fault segment to calibrate absolute amplitudes. We estimate the long period (1-10 seconds) ground motions for a suite of of M7+ scenario ruptures on the ISTL and explore the role of waveguides, basin resonance, and basin edges in strong ground motion.

  12. Geostatistical applications in petroleum geology and sedimentary geology

    SciTech Connect

    Murray, C.J.

    1992-01-01

    Statistical tools can aid the geologist in understanding geologic data, and in the solution of real-world problems. This thesis examines several tools, concentrating on techniques with wide applicability in sedimentary and petroleum geology. A case study presents the use of geostatistics for mapping hydrocarbon pore volume and risk assessment in an area surrounding Amos Draw field in the northern Powder River basin of Wyoming. The study used sequential Gaussian and indicator simulation techniques, and documents the ability of indicator simulation to incorporate correlated secondary data. Reservoir characterization requires the generation of numerical grids of geologic properties. Because those properties differ for each rock type, one should first simulate the distribution of rock types, and then the distribution of the reservoir properties. This thesis proposes two multivariate statistical techniques, discriminant function analysis and cluster analysis, for the identification of petrophysical rock types in the Muddy Formation at Amos Draw. The geology of those rock types is discussed using core descriptions, thin-sections, and well log data. The rock types were simulated in three dimensions using indicator principal component simulation. The study also used simulated annealing for post-processing of the simulations, incorporating information from the wells on the transition frequencies between the rock types. The third case study used runs analysis for the identification of patterns in bed thickness and grain size in turbidites. Upward-thickening and thinning patterns have been used to assign turbidite sequences to depositional environments, although there has been disagreement on their identification. Runs analysis was applied to a turbidite section in the Sites Formation at Cache Creek, in northern California.

  13. Rapid imbibition of water in fractures within unsaturated sedimentary rock

    NASA Astrophysics Data System (ADS)

    Cheng, C.-L.; Perfect, E.; Donnelly, B.; Bilheux, H. Z.; Tremsin, A. S.; McKay, L. D.; DiStefano, V. H.; Cai, J. C.; Santodonato, L. J.

    2015-03-01

    The spontaneous imbibition of water and other liquids into gas-filled fractures in variably-saturated porous media is important in a variety of engineering and geological contexts. However, surprisingly few studies have investigated this phenomenon. We present a theoretical framework for predicting the 1-dimensional movement of water into air-filled fractures within a porous medium based on early-time capillary dynamics and spreading over the rough surfaces of fracture faces. The theory permits estimation of sorptivity values for the matrix and fracture zone, as well as a dispersion parameter which quantifies the extent of spreading of the wetting front. Quantitative data on spontaneous imbibition of water in unsaturated Berea sandstone cores were acquired to evaluate the proposed model. The cores with different permeability classes ranging from 50 to 500 mD and were fractured using the Brazilian method. Spontaneous imbibition in the fractured cores was measured by dynamic neutron radiography at the Neutron Imaging Prototype Facility (beam line CG-1D, HFIR), Oak Ridge National Laboratory. Water uptake into both the matrix and the fracture zone exhibited square-root-of-time behavior. The matrix sorptivities ranged from 2.9 to 4.6 mm s-0.5, and increased linearly as the permeability class increased. The sorptivities of the fracture zones ranged from 17.9 to 27.1 mm s-0.5, and increased linearly with increasing fracture aperture width. The dispersion coefficients ranged from 23.7 to 66.7 mm2 s-1 and increased linearly with increasing fracture aperture width and damage zone width. Both theory and observations indicate that fractures can significantly increase spontaneous imbibition in unsaturated sedimentary rock by capillary action and surface spreading on rough fracture faces. Fractures also increase the dispersion of the wetting front. Further research is needed to investigate this phenomenon in other natural and engineered porous media.

  14. Correlating biodegradation to magnetization in oil bearing sedimentary rocks

    NASA Astrophysics Data System (ADS)

    Emmerton, Stacey; Muxworthy, Adrian R.; Sephton, Mark A.; Aldana, Milagrosa; Costanzo-Alvarez, Vincenzo; Bayona, German; Williams, Wyn

    2013-07-01

    A relationship between hydrocarbons and their magnetic signatures has previously been alluded to but this is the first study to combine extensive geochemical and magnetic data of hydrocarbon-associated samples. We report a detailed study that identifies a connection between magnetic mineralogy and oil biodegradation within oil-bearing sedimentary units from Colombia, Canada Indonesia and the UK. Geochemical data reveal that all the oil samples are derived from mature type-II kerogens deposited in oxygen-poor environments. Biodegradation is evident to some extent in all samples and leads to a decrease in oil quality through the bacterially mediated conversion of aliphatic hydrocarbons to polar constituents. The percentage of oil components and the biodegradation state of the samples were compared to the magnetic susceptibility and magnetic mineralogy. A distinct decrease in magnetic susceptibility is correlated to decreasing oil quality and the amount of extractable organic matter present. Further magnetic characterization revealed that the high quality oils are dominated by pseudo-single domain grains of magnetite and the lower quality oils by larger pseudo-single domain to multidomain grains of magnetite and hematite. Hence, with decreasing oil quality there is a progressive dominance of multidomain magnetite as well as the appearance of hematite. It is concluded that biodegradation is a dual process, firstly, aliphatic hydrocarbons are removed thereby reducing oil quality and secondly, magnetic signatures are both created and destroyed. This complex relationship may explain why controversy has plagued previous attempts to resolve the connection between magnetics and hydrocarbon deposits. These findings reinforce the importance of bacteria within petroleum systems as well as providing a platform for the use of magnetization as a possible exploration tool to identify subsurface reservoirs and a novel proxy of hydrocarbon migration.

  15. Nonlinear Chlorinated Solvent Sorption Impedes Remediation in Sedimentary Aquifers

    NASA Astrophysics Data System (ADS)

    Allen-King, R. M.; Rabideau, A. J.; Merlo, A.; Salvado i Estivill, J. A.; Barbarosa, V.; Matott, L. S.

    2014-12-01

    A 'tailing' pattern of rapid initial contaminant concentration decline followed by sustained release at a lower concentration is commonly produced by active remediation strategies. The ability of aquitard layers to cause this pattern is recognized. However, we hypothesize that nonlinear sorption combined with intragranular diffusion and mass storage within coarse, porous grains, can also cause tailing. Our project combines laboratory measurements of the equilibrium sorption isotherm for trichloroethene (TCE), release measurements from granular samples, and simulations of retarded intragranular diffusion. A novel aspect of our study is that we are examining a sample containing condensed kerogen as the primary form of organic matter on the impact of TCE mass storage, uptake and release rates. The kerogen-containing marine sedimentary rock used in our study is representative of the source rock of the surficial glacial aquifers in the southern Ontario, Canada region. The fact that energy producing shale units occur within the regional stratigraphic sequences indicates the high level of thermal maturation of the kerogen that comprises the sorbent for TCE in these samples. The equilibrium sorption isotherm spans nearly five orders of magnitude in aqueous concentration and is nonlinear. Preliminary comparisons between the mass release curve for grains equilibrated with a high TCE aqueous concentration (ca. 1000 mg/L) show that the physically-based model, which represents release controlled by intragranular diffusion with nonlinear local equilibrium sorption, provides a reasonable fit to the observed data with modest adjustment of the independently determined parameters. Additional experiments documenting TCE release from samples equilibrated at different initial aqueous concentrations and of different grain sizes will also be evaluated using the model and the results compared. Through extending simulations to the field scale, our results will contribute to a general

  16. Experiments on the dynamics and sedimentary products of glacier slip

    NASA Astrophysics Data System (ADS)

    Iverson, Neal R.; Zoet, Lucas K.

    2015-09-01

    Experimental work in glacial geomorphology is focused almost entirely on processes in the thin shear zone at the beds of sliding glaciers, where ice at its pressure-melting temperature moves over either rigid rock or deformable till. Experiments with rotary shear devices illuminate constitutive behavior there, central to the dynamics of fast-moving glaciers, and provide a foundation for interpreting the sedimentary record of glacier slip and associated sediment transport. Results from experiments designed to study ice sliding over a rigid wavy bed, shear deformation of till, and plowing of clasts across the surface of a till bed point to a common conclusion: drag at the bed can decrease with increasing slip velocity, thereby concentrating driving stress elsewhere and promoting rapid glacier flow. This rate-weakening behavior at glacier beds is in contrast to the viscous slip resistance assumed in ice-sheet models and most efforts to determine distributions of basal drag from glacier surface velocities. Ring-shear experiments in which various basal tills and more idealized materials are sheared to high strains provide quantitative insight into grain size evolution, mixing at contacts between basal tills, microstructure development, particle-fabric development, and development of anisotropy of magnetic susceptibility. Preferred orientations of principal magnetic susceptibilities provide the most dependable and complete description of till shear patterns. When applied to basal tills of the geologic record, magnetic till fabrics measured along thick till sections and calibrated experimentally indicate that deformation of the bed by two lobes of the Laurentide ice sheet was shallow (< 1 m), patchy, and occurred as till progressively accreted. Rates of sediment transport by bed shear were thus significantly less than estimates based on models that invoke deep, pervasive shear of the bed. The lack of an experimental tradition in glacial geomorphology leaves many research

  17. Looking for sedimentary basins using global gravity and crustal models

    NASA Astrophysics Data System (ADS)

    Colpani, Stefano; Strykowski, Gabriel

    2014-05-01

    Publically available and newly released global crustal model, CRUST 1.0 (Laske et al., 2013) in combination with satellite based global gravity models GOCO3s (Mayer-Gürr T. et al., 2012) yield a possibility of combining global source models with global gravity models. The depths to the top and to the base of the geological units obtained from the global crust model are used to fix the source geometry. This information is subsequently used to forward compute the global gravity signature of these units in different heights above the sources and for unit mass density. The average global mass density for the geological unit acts like a scaling factor and the relation to the gravity signal becomes linear. The computations are done both for Tz (gravity disturbances) and for some chosen gravity gradient components Tzz, Tzx and Tzy, where x,y and z refer to a local east-north-up Cartesian reference frame. The above setup allows constructing a model of the regional (gravity) field both for Tz and for the above gradient components Tzz, Tzx and Tzy and to improve it on regional scale. In principle, the method allows to keep track of the relation between the regional (gravity) signal and the source model. Subsequently, a generalized Nettleton's method can be used to fine-tune density values for the sediments from any above type of gravity data and a combination of it. Finally, for the well-surveyed areas, the results can be compared with the independent information about the basin geometry. This experience can be used for quantifying the information about the sedimentary basin in areas where the information is limited.

  18. Postglacial sedimentary infill of the Bricial peatland (Cantabrian Mountains, Spain)

    NASA Astrophysics Data System (ADS)

    Correia, Antonio; Ruiz-Fernández, Jesús; Oliva, Marc; Fernández, Antonio; García-Hernández, Cristina; Gallinar, David

    2016-04-01

    Bricial is a peatland located in a glaciokarst depression of the Western Massif of the Picos de Europa (NW Spain). The depression is 425 m long and 245 m wide, and it is surrounded by moraines built during the stage of glacial expansion after the maximum advance within the Last Glaciation. In contrast to what happens in other karstic depressions existing in this massif (e.g. Comeya), the thickness and sedimentary infill of this depression is still unknown. With the purpose of better knowing the depression's structure, two electrical resistivity tomographies (ERT)s with different lengths across the Bricial depression were conducted along perpendicular directions; the shortest ERT was done in a NNE-SSW direction with an electrode spacing of 2 m and a total length of 78 m; the longest ERT was done in a WNW-ESE direction with a 5 m electrode spacing and a total length of 195 m. Both ERTs used 40 electrodes in a Wenner configuration. The two ERTs were done in such way that they intersected near an 8 m deep borehole drilled in the area in 2006. A two-dimensional electrical inversion software was used for inverting the apparent electrical resistivity data obtained during the field work into two-dimensional models of electrical resistivity of the ground. The models are a representation of the distribution of the electrical resistivity of the ground to depths of about 14 m along the shortest ERT and 35 m along the longest. In both geoelectrical models the electrical structure is approximately horizontal at the surface (i.e., between 3 to 5 m depth) and is more complex as depth increases. Low resistivity values prevail in most part of the profiles, which is consistent with the sedimentary sequence collected in the area. The 8 m long sedimentary sequence collected from Bricial consists of homogeneous organic-rich sediments. The base of the sequence was dated at 11,150 ± 900 cal yr BP. Taking into account the sedimentation rates and the data inferred from the electrical

  19. Elemental geochemistry of sedimentary rocks at Yellowknife Bay, Gale crater, Mars.

    PubMed

    McLennan, S M; Anderson, R B; Bell, J F; Bridges, J C; Calef, F; Campbell, J L; Clark, B C; Clegg, S; Conrad, P; Cousin, A; Des Marais, D J; Dromart, G; Dyar, M D; Edgar, L A; Ehlmann, B L; Fabre, C; Forni, O; Gasnault, O; Gellert, R; Gordon, S; Grant, J A; Grotzinger, J P; Gupta, S; Herkenhoff, K E; Hurowitz, J A; King, P L; Le Mouélic, S; Leshin, L A; Léveillé, R; Lewis, K W; Mangold, N; Maurice, S; Ming, D W; Morris, R V; Nachon, M; Newsom, H E; Ollila, A M; Perrett, G M; Rice, M S; Schmidt, M E; Schwenzer, S P; Stack, K; Stolper, E M; Sumner, D Y; Treiman, A H; VanBommel, S; Vaniman, D T; Vasavada, A; Wiens, R C; Yingst, R A

    2014-01-24

    Sedimentary rocks examined by the Curiosity rover at Yellowknife Bay, Mars, were derived from sources that evolved from an approximately average martian crustal composition to one influenced by alkaline basalts. No evidence of chemical weathering is preserved, indicating arid, possibly cold, paleoclimates and rapid erosion and deposition. The absence of predicted geochemical variations indicates that magnetite and phyllosilicates formed by diagenesis under low-temperature, circumneutral pH, rock-dominated aqueous conditions. Analyses of diagenetic features (including concretions, raised ridges, and fractures) at high spatial resolution indicate that they are composed of iron- and halogen-rich components, magnesium-iron-chlorine-rich components, and hydrated calcium sulfates, respectively. Composition of a cross-cutting dike-like feature is consistent with sedimentary intrusion. The geochemistry of these sedimentary rocks provides further evidence for diverse depositional and diagenetic sedimentary environments during the early history of Mars.

  20. Modern and Fossil Raindrop Impressions as a Lesson in Interpretation of Ancient Sedimentary Features.

    ERIC Educational Resources Information Center

    Pardi, Richard R.; Brickner, Dorene

    1990-01-01

    Procedures for duplicating fossil raindrop impressions are presented. The use of modern and fossil imprints as the basis for qualitative and quantitative lessons in the interpretation of ancient sedimentary features is discussed. (CW)

  1. Evidence from carbon isotope measurements for diverse origins of sedimentary hydrocarbons

    NASA Technical Reports Server (NTRS)

    Freeman, K. H.; Hayes, J. M.; Trendel, J. M.; Albrecht, P.

    1990-01-01

    The organic matter found in sedimentary rocks must derive from many sources; not only from ancient primary producers but also from consumers and secondary producers. In all of these organisms, isotope effects can affect the abundance and distribution of 13C in metabolites. Here, by using an improved form of a previously described technique in which the effluent of a gas chromatograph is continuously analysed isotopically, we report evidence of the diverse origins of sedimentary organic matter. The record of 13C abundances in sedimentary carbonate and total organic carbon can be interpreted in terms of variations in the global carbon cycle. Our results demonstrate, however, that isotope variations within sedimentary organic mixtures substantially exceed those observed between samples of total organic carbon. Resolution of isotope variations at the molecular level offers a new and convenient means of refining views both of localized palaeoenvironments and of control mechanisms within the global carbon cycle.

  2. Space Station Views of African Sedimentary Basins-Analogs for Subsurface Patterns

    NASA Technical Reports Server (NTRS)

    Wilkinson, M. Justin

    2007-01-01

    Views of African sedimentary basins from the International Space Station (ISS) is presented. The images from ISS include: 1) Inland deltas; 2) Prediction; 3) Significance; 4) Exploration applications; and 5) Coastal megafans

  3. Fourier Series Optimization Opportunity

    ERIC Educational Resources Information Center

    Winkel, Brian

    2008-01-01

    This note discusses the introduction of Fourier series as an immediate application of optimization of a function of more than one variable. Specifically, it is shown how the study of Fourier series can be motivated to enrich a multivariable calculus class. This is done through discovery learning and use of technology wherein students build the…

  4. Welfare. Opposing Viewpoints Series.

    ERIC Educational Resources Information Center

    Cozic, Charles P., Ed.; Winters, Paul A., Ed.

    Books in the Opposing Viewpoints Series present debates about current issues that can be used to teach critical reading and thinking skills. The opinions expressed in the selections in each series title examine many different aspects of a single issue. Detractors of the welfare system have long argued that the system promotes dependency. They…

  5. Metallogenic Features and Series of the Mid-Lower Yantze Metallogenic Belt

    NASA Astrophysics Data System (ADS)

    Guo, K. Y.; Zeng, Y.; Chen, G. G.; Yuan, P.

    2012-12-01

    As part of the Circum-Pacific Metallogenic Belt, the metallogenic belt of copper, iron, sulfur and gold in the mid-lower reaches of the Yantze River is the most important copper-polymetallic metallogenic belt in East China. In the recent years, there has been continous new achievements for geological prospectings, especially deep prospecting, and breakthroughs for prospectings in new positions and of new types. I. Geological background of mineralization The mid-lower Yantze metallogenic belt has Dabie Uplift and Jiangnan Uplift on both sides, comprising a tectonic feature of "two convexes and one concave". Metallogenic sedimentary system The sedimentary system closely related to mineralization in mid-lower Yantze River includes neritic carbonate sedimentary rock series, hydrothermal exhalative sedimentary rock series, volcano-sedimentary rock series and clastic sedimentary rock series. Regional magmatism and mineralization Magmatic activities are extremely intense in the mid-lower Yantze area. Magmatic rocks are widely scattered and have a variety of types. Conspicuously controlled by regional structure in space, the Yanshanian period has developed into the most active duration of East China magmatic activites, bearing a close relationship with ores. Two stages of the Yanshanian tectonic-magmatic-metallogenism could be detected: the late Jurassic high-K calc-alkaline porphyry, magmatic-hydrothermal metallogenic belt of W, Sn, Au, Ag, Pb and Zn in Jiangnan and porphyry-skarn-hydrothermal metallogenic belt of Cu and Au in the lower Yantze; the early Cratecious porphyry contact-metasomatic hydrothermal ore cluster of Fe and S associated with shoshonite series in the lower Yantze, as a result of the underplating process of mantle-derived basaltic magma during the late orogeny. II. Regional metallogenic features The advantegous minerals of the mid-lower Yantze metallogenic belt includes Cu, Fe, Au, W, Mo, Pb, Zn, etc.. There are up to 103 types of ascertained mineral

  6. SERI Wind Energy Program

    SciTech Connect

    Noun, R. J.

    1983-06-01

    The SERI Wind Energy Program manages the areas or innovative research, wind systems analysis, and environmental compatibility for the U.S. Department of Energy. Since 1978, SERI wind program staff have conducted in-house aerodynamic and engineering analyses of novel concepts for wind energy conversion and have managed over 20 subcontracts to determine technical feasibility; the most promising of these concepts is the passive blade cyclic pitch control project. In the area of systems analysis, the SERI program has analyzed the impact of intermittent generation on the reliability of electric utility systems using standard utility planning models. SERI has also conducted methodology assessments. Environmental issues related to television interference and acoustic noise from large wind turbines have been addressed. SERI has identified the causes, effects, and potential control of acoustic noise emissions from large wind turbines.

  7. Sedimentary selenium as a causal factor for adverse biological effects: Toxicity thresholds and stream modeling

    SciTech Connect

    Va Derveer, W.; Canton, S.

    1995-12-31

    Selenium (Se) in the aquatic environment exhibits a strong association with particulate organic matter and as a result, measurements of waterborne concentration can be an unreliable predictor of bioaccumulation and adverse effects. Particulate-bound Se, typically measured as sedimentary Se, has been repeatedly implicated as a causal factor for Se bioaccumulation and subsequent potential for reproductive failures in fish and/or birds at sites receiving coal-fired power plant and refinery effluents as well as irrigation drainage. In fact, the premise that adverse biological effects are largely induced by sedimentary Se satisfies all of Hill`s criteria for a causal association. Despite these findings, most efforts to control Se continue to focus on waterborne concentrations because sedimentary toxicity thresholds are largely unknown. Sedimentary Se and associated biological effects data from studies of Se-bearing industrial effluent and irrigation drainage were compiled to initiate development of biological effects thresholds, The probability of adverse effects on fish or birds appears to be low up to a sedimentary Se concentration of about 2.8 {micro}g/g dry weight and high at 6.4 {micro}g/g dry weight (10th and 50th percentile of effects data, respectively). In addition, a preliminary regression model was derived for predicting dissolved to sedimentary Se transfer in streams as an interactive function of site-specific sedimentary organic carbon content (R{sup 2} = 0,870, p < 0.001) based on irrigation drainage studies in Colorado. This dissolved Se interaction with sedimentary organic carbon provides a possible explanation for the variable biological response to waterborne Se-organic-rich sites are predisposed to greater Se bioaccumulation and subsequent biological effects than organic-poor sites.

  8. Coastal sedimentary research examines critical issues of national and global priority

    USGS Publications Warehouse

    Fletcher, Chip; Anderson, John; Crook, Keith A.W.; Kaminsky, George; Larcombe, Piers; Murray-Wallace, Colin V.; Sansone, Frank; Scott, David B.; Riggs, Stan; Sallenger, Asbury; Shennan, Ian; Thieler, E. Robert; Wehmiller, John F.

    2000-01-01

    An international conference was held recently in Honolulu, Hawaii, to examine and plan for coastal sedimentary research in the United States and globally. Participants agreed that sedimentary coastal environments constitute a critical national and global resource that suffers widespread degradation due to human impacts. Moreover, human population growth and inappropriate development in the coastal zone are escalating public asset losses due to coastal hazards and placing large numbers of communities at growing risk (Figure 1).

  9. Laboratory simulated hydrothermal alteration of sedimentary organic matter from Guaymas Basin, Gulf of California. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Leif, Roald N.

    1993-01-01

    High temperature alteration of sedimentary organic matter associated with marine hydrothermal systems involves complex physical and chemical processes that are not easily measured in most natural systems. Many of these processes can be evaluated indirectly by examining the geochemistry of the hydrothermal system in the laboratory. In this investigation, an experimental organic geochemical approach to studying pyrolysis of sedimentary organic matter is applied to the hydrothermal system in the Guaymas Basin, Gulf of California. A general survey of hydrothermal oils and extractable organic matter (bitumen) in hydrothermally altered sediments identified several homologous series of alkanones associated with a high temperature hydrothermal origin. The alkanones range in carbon number from C11 to C30 with no carbon number preference. Alkan-2-ones are in highest concentrations, with lower amounts of 3-, 4-, 5- (and higher) homologs. The alkanones appear to be pyrolysis products synthesized under extreme hydrothermal conditions. Hydrous pyrolysis and confinement pyrolysis experiments were performed to simulate thermally enhanced diagenetic and catagenetic changes in the immature sedimentary organic matter. The extent of alteration was measured by monitoring the n-alkanes, acyclic isoprenoids, steroid and triterpenoid biomarkers, polycyclic aromatic hydrocarbons and alkanones. The results were compared to bitumen extracts from sediments which have been naturally altered by a sill intrusion and accompanied hydrothermal fluid flow. These pyrolysis experiments duplicated many of the organic matter transformations observed in the natural system. Full hopane and sterane maturation occurred after 48 hr in experiments at 330 deg C with low water/rock mass ratios (0.29). A variety of radical and ionic reactions are responsible for the organic compound conversions which occur under extreme hydrothermal conditions. Short duration pyrolysis experiments revealed that a portion of the

  10. Stratigraphic architecture and forcing processes of the late Neogene Miradouro da Lua sedimentary prism, Cuanza Basin, Angola

    NASA Astrophysics Data System (ADS)

    Cauxeiro, C.; Durand, J.; Lopez, M.

    2014-07-01

    The Miradouro da Lua cliffs, which are 60 km south of Luanda, record the building and uplift of the late Neogene Palaeo-Cuanza delta. The detailed study of the sedimentary architecture and stacking pattern permitted separation of the pile into five depositional units bounded by erosional surfaces and characterised by separate facies associations (genetic sequences = units in this paper). At the base of the series, aeolian deposits (Unit 1) mark the development of a possible coastal desert during the late Miocene aridification. The major Pliocene sea-level rise (Transgressive Systems Tract) led to the drowning of the continental platform into a discrete shoreface-foreshore sequence (Unit 2), followed by an expanded deltaic sequence (Unit 3) that represents the main outcrop of the area. The sedimentary fabric of this prograding wedge during the Highstand Systems Tract reveals laterally stacked pluri-hectometic mouth bars built by the abrupt switching of a bird-foot delta during the Pliocene highstand. The clinoforms are deeply incised by submarine gullies filled both by periodic river-driven turbidite and tidal currents (Unit 4) during the coeval growing of the delta. The topset of the prograding wedge and associated gullies infill is truncated by an overall erosional unconformity that marks the widespread development of an extensive braid-delta system (Unit 5) during the lower Pleistocene sea-level drop (Lowstand Systems Tract). The last 6 m of the Braid-delta unit is overprinted by a ferallitic profile, forming the surface of the plateau and indicating long-term subaerial exposure and weathering processes consistent with the maximum warming of the middle to late Pleistocene interglacial periods. The successive abrupt shifts of the depositional systems through the sedimentary pile indicate a high-amplitude sea level amplified by major coastal uplifts and the reorganisation of the fluvial network. In this context, the palaeo-Cuanza prograding wedge signals the

  11. Evaluation of heat generation by radioactive decay of sedimentary rocks in Eastern Desert and Nile Valley, Egypt.

    PubMed

    Abbady, Adel G E

    2010-10-01

    Radioactive heat-production (RHP) data of sedimentary outcrops in Gebel Anz (Eastern Desert) and Gebel Sarai (Nile Valley) are presented. A total of 103 rock samples were investigated, covering all major rock types of the areas. RHP were derived from uranium, thorium and potassium concentrations measured from gamma-radiation originating from the decay of (214)Bi ((238)U series), (208)Tl ((232)Th series) and the primary decay of (40)K, obtained with a NaI (Tl) detector. The heat-production rate of Gebel Anz ranges from 0.94 (Nubai Sandstone ) to 5.22 microW m(-3) (Duwi Formation). In Gebel Sarai it varies from 0.82 (Esna Shale) to 7 microW m(-3) (Duwi Formation). The contribution due to U is about 62%, from Th is 34% and 4% from K in Gebel Anz. The corresponding values in Gebel Sarai are 69.6%, 26.9% and 3.5%, respectively. These data can be used to discuss the effects of the lateral variation of the RHP rate on the heat flux and the temperature fields in the upper crust.

  12. Geophysical modeling of the structural relationships between the Precambrian Reading Prong rocks and the Paleozoic sedimentary sequence, Easton quadrangle, PA

    SciTech Connect

    Thomas, D.M.; Malinconico, L.L. Jr. . Dept. of Geology)

    1993-03-01

    This project involves the geophysical modeling of the structural relationships between the Precambrian Reading Prong rocks and the Paleozoic sedimentary cover rocks near Easton, Pennsylvania. The Precambrian rocks have generally been assumed to have been emplaced on the Paleozoic sequence along a shallow thrust fault. However, at present time the attitude of the faults bordering the Precambrian terranes are all very steeply dipping. This was explained by the subsequent folding of the whole sequence during later orogenic activity. The objective of this work is to determine the attitude and depth of the fault contact between the Precambrian crystalline rocks and the Paleozoic sedimentary rocks. A series of traverses (each separated by approximately one mile) were established perpendicular to the strike of the Precambrian rocks. Along each traverse both gravity and magnetic readings were taken at 0.2 kilometer intervals. The data were reduced and presented as profiles and contour maps. Both the magnetic and gravity data show positive anomalies that correlate spatially with the location of the Precambrian rocks. The gravity data have a long wavelength regional trend increasing to the north with a shorter wavelength anomaly of 2 milligals which coincides with the Precambrian rocks. The magnetic data have a single positive anomaly of almost 1,000 gammas which also coincides with the Precambrian terrane. These data will now be used to develop two dimensional density and susceptibility models of the area. From these models, the thickness of each formation and the structural relationships between them, as well as the attitude and depth of the fault contact will be determined.

  13. Organic chemical and biomarker analyses of terrestrial archives - is all what we measure of sedimentary origin?

    NASA Astrophysics Data System (ADS)

    Wiesenberg, G. L.; Gocke, M.

    2012-12-01

    Organic chemical analyses of sedimentary organic matter have been widely used in the past. In terrestrial archives total carbon, organic carbon (Corg) and carbonatic carbon (Ccarb) and their stable isotope composition (δ13C) were established for source assessment of sedimentary matter covering source area (Ccarb) and source vegetation (Corg). Furthermore, radiocarbon dating (Δ14C) was found useful to date sedimentary archives covering the past 50 ka. In addition, the application of biomarkers was tried in sedimentary archives like loess-paleosol sequences to trace source vegetation in more detail. Among others, several alkane molecular proxies have been introduced and adopted in order to assess the contribution of tree and grass vegetation to sedimentary organic matter. Furthermore, other biomarkers like alcohols, fatty acids and others were introduced into the investigation of terrestrial archives. However, studies of the recent 10 years clearly indicate that overprint of sedimentary matter is very likely for terrestrial archives and that caution should be paid, when interpreting chemical results. While secondary carbonate formation is a well known feature covering e.g. loess dolls, pseudomycelia and rhizoliths, commonly these features are not mentioned correctly in a paleoenvironmental context. Nevertheless, they provide unique opportunities for the reassessment of potential contamination of sedimentary organic matter. Especially rhizoliths as calcified root remains can impressively cut vertically through several pairs of sediments and paleosols. While some authors still suggest their formation during sedimentation, we could clearly show different ages of sediments and rhizoliths from the same depth. While some of these root features are easy to see during field campaigns, others are not. This is e.g. observed for biopores in the vicinity of rhizoliths. They can have diameters <0.1 mm and are associated with former fine roots, which must not necessarily be

  14. Sedimentary processes in the middle Nazaré Canyon

    NASA Astrophysics Data System (ADS)

    Masson, D. G.; Huvenne, V. A. I.; de Stigter, H. C.; Arzola, R. G.; LeBas, T. P.

    2011-12-01

    Nazaré Canyon extends from a water depth of 50 m near the Portuguese coast to 5000 m at the edge of the Iberian Abyssal Plain. The system is not connected to a modern river and instead obtains its present day sediment input by capture of along-shelf sediment transport. Much of this sediment is deposited in the middle canyon between about 2700 and 3800 m. However, the middle canyon is a highly heterogeneous environment, with areas of both high and low sedimentation rates, exposed rock outcrop, erosion and stable and unstable slopes in close juxtaposition. This paper explores how the various sedimentary processes interact to create the observed heterogeneous canyon environment, which will influence benthic biodiversity in the canyon. Seafloor heterogeneity is investigated using a nested approach to data interpretation, using local high-resolution data to calibrate regional lower resolution data. Six different data types, ship and ROV-mounted swath bathymetry, 30 kHz sidescan sonar images, sediment cores, seafloor video/photographs and current metre/acoustic backscatter data, were incorporated into the analysis. The main morphological characteristic of the middle canyon is a narrow, steep-sided, axial channel flanked by gently sloping terraces. Small-scale landsliding, active at the present day, is the main process that exposes a variety of substrates, ranging from semi-consolidated Holocene sediments to rock of probable Mesozoic age, on the steep axial channel walls. The axial channel floor is characterised in part by large-scale sediment bedforms and in part by landslide debris, suggesting some reworking of landslide debris by currents within the channel. The terraces are interpreted as inner levees with high sedimentation rates. Cores show a dominantly muddy sequence interrupted by thin turbidite sands emplaced on decadal to centennial timescales. The fine-grained sedimentation is the product of continuous settling from fine-grained flows that range from gravity

  15. Rapid imbibition of water in fractures within unsaturated sedimentary rock

    SciTech Connect

    Cheng, Chu-Lin; Perfect, Edmund; Donnelly, B.; Bilheux, Hassina Z.; Tremsin, Anton S.; McKay, L. D.; Distefano, Victoria H.; Cai, J. C.; Santodonato, Louis J.

    2015-01-27

    The spontaneous imbibition of water and other liquids into gas-filled fractures in variably-saturated porous media is important in a variety of engineering and geological contexts. However, surprisingly few studies have investigated this phenomenon. In this paper, we present a theoretical framework for predicting the 1-dimensional movement of water into air-filled fractures within a porous medium based on early-time capillary dynamics and spreading over the rough surfaces of fracture faces. The theory permits estimation of sorptivity values for the matrix and fracture zone, as well as a dispersion parameter which quantifies the extent of spreading of the wetting front. Quantitative data on spontaneous imbibition of water in unsaturated Berea sandstone cores were acquired to evaluate the proposed model. The cores with different permeability classes ranging from 50 to 500 mD and were fractured using the Brazilian method. Spontaneous imbibition in the fractured cores was measured by dynamic neutron radiography at the Neutron Imaging Prototype Facility (beam line CG-1D, HFIR), Oak Ridge National Laboratory. Water uptake into both the matrix and the fracture zone exhibited square-root-of-time behavior. The matrix sorptivities ranged from 2.9 to 4.6 mm s-0.5, and increased linearly as the permeability class increased. The sorptivities of the fracture zones ranged from 17.9 to 27.1 mm s-0.5, and increased linearly with increasing fracture aperture width. The dispersion coefficients ranged from 23.7 to 66.7 mm2 s-1 and increased linearly with increasing fracture aperture width and damage zone width. Both theory and observations indicate that fractures can significantly increase spontaneous imbibition in unsaturated sedimentary rock by capillary action and surface spreading on rough fracture faces. Fractures also increase the dispersion of the wetting front. In conclusion, further research is needed to investigate this phenomenon

  16. Sedimentary reservoir oxidation during geologic CO2 sequestration

    NASA Astrophysics Data System (ADS)

    Lammers, Laura N.; Brown, Gordon E.; Bird, Dennis K.; Thomas, Randal B.; Johnson, Natalie C.; Rosenbauer, Robert J.; Maher, Katharine

    2015-04-01

    Injection of carbon dioxide into subsurface geologic reservoirs during geologic carbon sequestration (GCS) introduces an oxidizing supercritical CO2 phase into a subsurface geologic environment that is typically reducing. The resulting redox disequilibrium provides the chemical potential for the reduction of CO2 to lower free energy organic species. However, redox reactions involving carbon typically require the presence of a catalyst. Iron oxide minerals, including magnetite, are known to catalyze oxidation and reduction reactions of C-bearing species. If the redox conditions in the reservoir are modified by redox transformations involving CO2, such changes could also affect mineral stability, leading to dissolution and precipitation reactions and alteration of the long-term fate of CO2 in GCS reservoirs. We present experimental evidence that reservoirs with reducing redox conditions are favorable environments for the relatively rapid abiotic reduction of CO2 to organic molecules. In these experiments, an aqueous suspension of magnetite nanoparticles was reacted with supercritical CO2 under pressure and temperature conditions relevant to GCS in sedimentary reservoirs (95-210 °C and ∼100 bars of CO2). Hydrogen production was observed in several experiments, likely caused by Fe(II) oxidation either at the surface of magnetite or in the aqueous phase. Heating of the Fe(II)-rich system resulted in elevated PH2 and conditions favorable for the reduction of CO2 to acetic acid. Implications of these results for the long-term fate of CO2 in field-scale systems were explored using reaction path modeling of CO2 injection into reservoirs containing Fe(II)-bearing primary silicate minerals, with kinetic parameters for CO2 reduction obtained experimentally. The results of these calculations suggest that the reaction of CO2 with reservoir constituents will occur in two primary stages (1) equilibration of CO2 with organic acids resulting in mineral-fluid disequilibrium, and

  17. Structures and sedimentary deposition in the Sunda Strait, Indonesia

    NASA Astrophysics Data System (ADS)

    Susilohadi, Susilohadi; Gaedicke, Christoph; Djajadihardja, Yusuf

    2009-03-01

    The Sunda Strait lies between the islands of Java and Sumatra and separates the nearly orthogonal subduction along the south of Java and oblique subduction beneath Sumatra. The Sumatra fault accommodating most of the trench parallel shear of the oblique subduction initiates in the Sunda Strait. This setting implies that the Sunda Strait is an attractive area to study the geodynamic evolution of the western Indonesian region. Thirteen multichannel seismic lines acquired in the Sunda Strait have allowed a detailed study of the structure, sedimentation patterns and volcanic activities that occurred in the Sunda Strait. The Sunda Strait evolution has been strongly tied with the development of the Sumatra fault in this area. The opening of the Sunda Strait initiated in the early Late Miocene following the commencement of the Sumatra fault system in the Middle Miocene. Since then, three major graben systems have been evolved, which are referred to as the West and East Semangko Grabens, and the Krakatau Graben. These graben systems can be regarded as pull-apart basins developed within the releasing fault overstep area in between the main strand of the Sumatra fault and its relay faults south off Ujung Kulon. Prior to the Late Miocene most of the Sunda Strait and the surroundings probably developed in a non-marine environment. In Late Miocene the Sunda Strait started to open and volcanism began and has been the main source of clastics. Three major sedimentary units can be identified which represent Late Miocene, Pliocene and Pleistocene sediments respectively. The Late Miocene unit has been developed in the shelfal area on top of the Middle Miocene unconformity following a relative rapid sea level rise, and a subsequent highstand prior to the sea level fall at the end of Miocene. Its lower part has syn-structurally been deposited into the Late Miocene basement block faulting. The early deposition of the Pliocene unit was in response to the Pliocene sea level rise and

  18. Time Series Explorer

    NASA Astrophysics Data System (ADS)

    Scargle, J.

    With the generation of long, precise, and finely sampled time series the Age of Digital Astronomy is uncovering and elucidating energetic dynamical processes throughout the Universe. Fulfilling these opportunities requires data effective analysis techniques rapidly and automatically implementing advanced concepts. The Time Series Explorer, under development in collaboration with Tom Loredo, provides tools ranging from simple but optimal histograms to time and frequency domain analysis for arbitrary data modes with any time sampling. Examples of application of these tools for automated time series discovery will be given.

  19. The Death of the Dinosaurs: 27 Years Later (LBNL Summer Lecture Series)

    SciTech Connect

    Muller, Rich

    2006-06-30

    Summer Lecture Series 2006: Rich Muller, a Berkeley Lab physicist, discusses Nobel laureate Luis Alvarez and colleagues' 1979 discovery that an asteroid impact killed the dinosaurs. He also discusses what scientists have learned in the subsequent 27 years. Alvarez's team detected unusual amounts of iridium in sedimentary layers. They attributed the excess iridium to an impact from a large asteroid. His talk was presented June 30, 2006.

  20. The Death of the Dinosaurs: 27 Years Later (LBNL Summer Lecture Series)

    ScienceCinema

    Muller, Rich

    2016-07-12

    Summer Lecture Series 2006: Rich Muller, a Berkeley Lab physicist, discusses Nobel laureate Luis Alvarez and colleagues' 1979 discovery that an asteroid impact killed the dinosaurs. He also discusses what scientists have learned in the subsequent 27 years. Alvarez's team detected unusual amounts of iridium in sedimentary layers. They attributed the excess iridium to an impact from a large asteroid. His talk was presented June 30, 2006.

  1. 3D Inversion of Gravity Anomalies for the Interpretation of Sedimentary Basins using Variable Density Contrast

    NASA Astrophysics Data System (ADS)

    Ekinci, Yunus Levent; Ertekin, Can

    2015-04-01

    Concern about sedimentary basins is generally related to their genetic and economic significance. Analysis of sedimentary basins requires the acquisition of data through outcrop studies and subsurface investigations that encompass drilling and geophysics. These data are commonly analysed by computer-assisted techniques. One of these methods is based on analysing gravity anomalies to compute the depth of sedimentary basin-basement rock interface. Sedimentary basins produce negative gravity anomalies, because they have mostly lower densities than that of the surrounding basement rocks. Density variations in a sedimentary fill increase rapidly at shallower depths then gradually reach the density of surrounding basement rocks due to the geostatic pressure i.e. compaction. The decrease of the density contrast can be easily estimated by a quadratic function. Hence, if the densities are chosen properly and the regional background is removed correctly, the topographical relief of the sedimentary basin-basement rock interface might be estimated by the inversion of the gravity data using an exponential density-depth relation. Three dimensional forward modelling procedure can be carried out by introducing a Cartesian coordinate system, and placing vertical prisms just below observation points on the grid plane. Depth to the basement, namely depths to the bottom of the vertical prisms are adjusted in an iterative manner by minimizing the differences between measured and calculated residual gravity anomalies. In this study, we present a MATLAB-based inversion code for the interpretation of sedimentary basins by approximating the topographical relief of sedimentary basin-basement rock interfaces. For a given gridded residual gravity anomaly map, the procedure estimates the bottom depths of vertical prisms by considering some published formulas and assumptions. The utility of the developed inversion code was successfully tested on theoretically produced gridded gravity data set

  2. Upper Gastrointestinal (GI) Series

    MedlinePlus

    ... barium or flavoring in the barium intestinal obstruction Seek care right away If you have any of the following symptoms after an upper GI series, seek medical attention right away: fever no bowel movement ...

  3. Lower GI Series

    MedlinePlus

    ... GI series. • an allergic reaction to the barium. • bowel obstruction—partial or complete blockage of the small or large intestine. Although rare, bowel obstruction can be a life-threatening condition that requires ...

  4. Time Series Explorer

    NASA Astrophysics Data System (ADS)

    Loredo, Thomas

    The key, central objectives of the proposed Time Series Explorer project are to develop an organized collection of software tools for analysis of time series data in current and future NASA astrophysics data archives, and to make the tools available in two ways: as a library (the Time Series Toolbox) that individual science users can use to write their own data analysis pipelines, and as an application (the Time Series Automaton) providing an accessible, data-ready interface to many Toolbox algorithms, facilitating rapid exploration and automatic processing of time series databases. A number of time series analysis methods will be implemented, including techniques that range from standard ones to state-of-the-art developments by the proposers and others. Most of the algorithms will be able to handle time series data subject to real-world problems such as data gaps, sampling that is otherwise irregular, asynchronous sampling (in multi-wavelength settings), and data with non-Gaussian measurement errors. The proposed research responds to the ADAP element supporting the development of tools for mining the vast reservoir of information residing in NASA databases. The tools that will be provided to the community of astronomers studying variability of astronomical objects (from nearby stars and extrasolar planets, through galactic and extragalactic sources) will revolutionize the quality of timing analyses that can be carried out, and greatly enhance the scientific throughput of all NASA astrophysics missions past, present, and future. The Automaton will let scientists explore time series - individual records or large data bases -- with the most informative and useful analysis methods available, without having to develop the tools themselves or understand the computational details. Both elements, the Toolbox and the Automaton, will enable deep but efficient exploratory time series data analysis, which is why we have named the project the Time Series Explorer. Science

  5. Sedimentary structures and stratal geometries at the foothills of Mount Sharp: their role in paleoenvironmental interpretation

    NASA Astrophysics Data System (ADS)

    Gupta, S.; Rubin, D. M.; Sumner, D. Y.; Grotzinger, J. P.; Lewis, K. W.; Stack, K.; Kah, L. C.; Banham, S.; Edgett, K. S.

    2015-12-01

    The Mars Science Laboratory Curiosity rover has been exploring sedimentary rocks at the foothills of Mount Sharp since August 2014. Robust interpretation of the paleoenvironmental contexts requires detailed facies analysis of these rocks including analysis and interpretation of sedimentary structures and sediment body geometries. Here, we describe some of the detailed sedimentary structures and sedimentary geometries observed by Curiosity between the Pahrump_Hills field site and its current location at Marias Pass. The Pahrump Hills sedimentary section comprises a succession dominated by finely laminated mudstones of the Murray formation that are interpreted to have been deposited in an ancient lake within Gale crater. Toward the top of the Pahump Hills succession, we observe the appearance of coarser-grained sandstones that are interstratified within the lacustrine mudstones. These sandstones that include Whale Rock and Newspaper Rock show lenticular geometries, and are pervasively cross-stratified. These features indicate that currents eroded shallow scours in the lake beds that were then infilled by deposition from migrating subaqueous dunes. The paleoenvironmental setting may represent either a gullied delta front setting or one in which lake level fall caused fluvial erosion and infilling of the shallow scours. Since leaving Pahrump_Hills, Curiosity has imaged extensive exposures of strata that are partly correlative with and stratigraphically overlie the uppermost part of the Pahrump section. Isolated cross-bedded sandstones and possible interstratified conglomerates beds occur within Murray formation mudstones. Capping sandstones with a likely variety of environmental contexts overlie mudstones. Where imaged in detail, sedimentary structures, such as trough-cross bedding and possible eolian pinstriping, provide constraints on plausible sedimentary processes and bounds on depositional setting.

  6. Late Quaternary sedimentary features of Bear Lake, Utah and Idaho

    USGS Publications Warehouse

    Smoot, J.P.

    2009-01-01

    Bear Lake sediments were predominantly aragonite for most of the Holocene, reflecting a hydrologically closed lake fed by groundwater and small streams. During the late Pleistocene, the Bear River flowed into Bear Lake and the lake waters spilled back into the Bear River drainage. At that time, sediment deposition was dominated by siliciclastic sediment and calcite. Lake-level fluctuation during the Holocene and late Pleistocene produced three types of aragonite deposits in the central lake area that are differentiated primarily by grain size, sorting, and diatom assemblage. Lake-margin deposits during this period consisted of sandy deposits including well-developed shoreface deposits on margins adjacent to relatively steep gradient lake floors and thin, graded shell gravel on margins adjacent to very low gradient lake-floor areas. Throughout the period of aragonite deposition, episodic drops in lake level resulted in erosion of shallow-water deposits, which were redeposited into the deeper lake. These sediment-focusing episodes are recognized by mixing of different mineralogies and crystal habits and mixing of a range of diatom fauna into poorly sorted mud layers. Lake-level drops are also indicated by erosional gaps in the shallow-water records and the occurrence of shoreline deposits in areas now covered by as much as 30 m of water. Calcite precipitation occurred for a short interval of time during the Holocene in response to an influx of Bear River water ca. 8 ka. The Pleistocene sedimentary record of Bear Lake until ca. 18 ka is dominated by siliciclastic glacial fl our derived from glaciers in the Uinta Mountains. The Bear Lake deep-water siliciclastic deposits are thoroughly bioturbated, whereas shallow-water deposits transitional to deltas in the northern part of the basin are upward-coarsening sequences of laminated mud, silt, and sand. A major drop in lake level occurred ca. 18 ka, resulting in subaerial exposure of the lake floor in areas now covered by

  7. Rivers on Titan - numerical modelling of sedimentary structures

    NASA Astrophysics Data System (ADS)

    Misiura, Katarzyna; Czechowski, Leszek

    2016-07-01

    flow and of the sedimentation on Titan and on the Earth. Our preliminary results indicate that suspended load is the main way of transport in simulated Titan's conditions. We also indicate that braided rivers appears for larger range of slope on Titan (e.g. S=0.01-0.04) than on Earth (e.g. S=0.004-0.009). Also, for the same type of river, the grain size on Titan is at least 10 times larger than on Earth (1 cm for Titan versus 1 mm for the Earth). It is very interesting that on Titan braided rivers appear even for very little discharge (e.g. Q=30m3/s) and for very large grain size (e.g. 10 cm). In the future we plan the experimental modelling in sediment basin to confirm results from computer modelling. Acknowledgements We are very grateful to Yaoxin Zhang and Yafei Jia from National Center for Computational Hydroscience and Engineering for providing their program - CCHE2D. References [1] Misiura, K., Czechowski, L., 2015. Numerical modelling of sedimentary structures in rivers on Earth and Titan. Geological Quarterly, 59(3): 565-580. [2] Witek, P., Czechowski, L., 2015. Dynamical modeling of river deltas on Titan and Earth. Planet. Space. Sci., 105: 65-79.

  8. Seismic interaction between a building network and a sedimentary basin

    NASA Astrophysics Data System (ADS)

    Kham, M.; Semblat, J. F.; Bard, P. Y.; Gueguen, P.

    2003-04-01

    The classical procedure to assess the seismic risk for a superficial structure consists in distinguishing firstly the characterization of the seismic hazard and secondly the analysis of the structure vulnerability. But, as far as the entire urban area is concerned by the seismic risk, a network of superficial structures may influence the free-field motion. In this way, convergent observations were made during the 1985 Mexico earthquake where the large increase in duration may not be completely explained only by site effects. This phenomenon involving the interaction between a city and the sedimentary basin is called Site-City Interaction (SCI) and was firstly underlined by Gueguen [1] in Volvi european test site. Under seismic excitation, the energy radiated by the city back into the soil seems to be mainly controlled by the eigenfrequency ratio fB/fs between the buildings and the soil as well as the urban density. Nevertheless, the key parameters supporting or controlling the SCI effect mainly remain unknown. This point is all the more obvious since present studies on the issue suffer a lack of experimental data characterizing the "urban free field". In the present work, we aim to quantify the specific role of some parameters characterizing the city on seismic hazard modification, such as the urban density, the resonance frequency of the buildings in the city, its homogeneity level (one or several types of different buildings) or the periodicity (or not) of the buildings distribution. To this purpose, a boundary element model is considered which comprises alluvial layers over a rigid elastic basement and superficial buildings. Impedance contrast is taken to 5 in order to support the trapping of the incident energy inside the superficial layers. The whole system is then submitted to a Ricker signal which frequency is successively adjusted to the city and the soil fundamental frequencies. The case of Nice city (France) over a two dimensional basin is then considered

  9. Origin of orbital periods in the sedimentary relative paleointensity records

    NASA Astrophysics Data System (ADS)

    Xuan, Chuang; Channell, James E. T.

    2008-08-01

    Orbital cycles with 100 kyr and/or 41 kyr periods, detected in some sedimentary normalized remanence (relative paleointensity) records by power spectral analysis or wavelet analysis, have been attributed either to orbital forcing of the geodynamo, or to lithologic contamination. In this study, local wavelet power spectra (LWPS) with significance tests have been calculated for seven relative paleointensity (RPI) records from different regions of the world. The results indicate that orbital periods (100 kyr and/or 41 kyr) are significant in some RPI records during certain time intervals, and are not significant in others. Time intervals where orbital periods are significant are not consistent among the RPI records, implying that orbital periods in these RPI records may not have a common origin such as orbital forcing on the geodynamo. Cross-wavelet power spectra (|XWT|) and squared wavelet coherence (WTC) between RPI records and orbital parameters further indicate that common power exists at orbital periods but is not significantly coherent, and exhibits variable phase relationships, implying that orbital periods in RPI records are not caused directly by orbital forcing. Similar analyses for RPI records and benthic oxygen isotope records from the same sites show significant coherence and constant in-phase relationships during time intervals where orbital periods were significant in the RPI records, indicating that orbital periods in the RPI records are most likely due to climatic 'contamination'. Although common power exists at orbital periods for RPI records and their normalizers with significant coherence during certain time intervals, phase relationships imply that 'contamination' (at orbital periods) is not directly due to the normalizers. Orbital periods are also significant in the NRM intensity records, and 'contamination' in RPI records can be attributed to incomplete normalization of the NRM records. Further tests indicate that 'contamination' is apparently

  10. On Sums of Numerical Series and Fourier Series

    ERIC Educational Resources Information Center

    Pavao, H. Germano; de Oliveira, E. Capelas

    2008-01-01

    We discuss a class of trigonometric functions whose corresponding Fourier series, on a conveniently chosen interval, can be used to calculate several numerical series. Particular cases are presented and two recent results involving numerical series are recovered. (Contains 1 note.)

  11. Sedimentary Record of syn- and Post-Glacial Climate Change Along the Former LGM ice Terminus, Flathead Lake, Montana

    NASA Astrophysics Data System (ADS)

    Hendrix, M. S.; Hofmann, M.; Moore, J. N.; Sperazza, M.

    2006-12-01

    Located west of the continental divide at the former LGM terminal position of the Flathead Lobe of the Cordilleran Ice Sheet, Flathead Lake (Montana) contains a well preserved record of syn- and post-glacial Quaternary sedimentation. We have studied this record through a combination of geologic mapping around the lake margins, 3.5 kHz and lower frequency seismic reflection profiling of lake sediments, and coring of the lake floor. The oldest part of the Quaternary sedimentary record comprises ice-contact till exposed along the lake basin margins and imaged in deep seismic reflection profiles. Sedimentary facies and geomorphology of the terminal moraine suggest that the Flathead Lobe flowed into a major proglacial lake, probably glacial Lake Missoula. The oldest core sediments recovered from the lake basin consist of a series of clay-rich glacial varves that thin- and fine-upward. These are overlain by a series of anomalously coarse silt beds, each containing a sharp base, upward fining grain size, and lakewide distribution. Depositional age of these beds is constrained as between 14,150±150 cal. Yr BP (14C date on a pine needle below the beds) and 13,180±120 cal. Yr BP (Glacier Peak tephra above the beds). We interpret the silt beds to reflect pulses of sediment delivered to the Flathead Lake basin by high discharge flood events associated with rapid retreat of the Flathead Lobe and possible rapid release of proglacial melt water from upstream tributary valleys dammed by the Flathead Lobe. The transition of Flathead Lake from a proglacial lake to the modern oligotrophic lake system took place shortly after deposition of the Glacier Peak tephra. Interestingly, none of our 8 deep piston cores display an obvious Younger Dryas sedimentologic signal. Holocene core records, combined with information from 3.5 kHz seismic data, indicate periods of significant lake level fluctuation that are likely climate-driven. Of these, the most significant lake drawdown immediately

  12. Sources of sedimentary PAHs in tropical Asian waters: differentiation between pyrogenic and petrogenic sources by alkyl homolog abundance.

    PubMed

    Saha, Mahua; Togo, Ayako; Mizukawa, Kaoruko; Murakami, Michio; Takada, Hideshige; Zakaria, Mohamad P; Chiem, Nguyen H; Tuyen, Bui Cach; Prudente, Maricar; Boonyatumanond, Ruchaya; Sarkar, Santosh Kumar; Bhattacharya, Badal; Mishra, Pravakar; Tana, Touch Seang

    2009-02-01

    We collected surface sediment samples from 174 locations in India, Indonesia, Malaysia, Thailand, Vietnam, Cambodia, Laos, and the Philippines and analyzed them for polycyclic aromatic hydrocarbons (PAHs) and hopanes. PAHs were widely distributed in the sediments, with comparatively higher concentrations in urban areas (Sigma PAHs: approximately 1000 to approximately 100,000 ng/g-dry) than in rural areas ( approximately 10 to approximately 100g-dry), indicating large sources of PAHs in urban areas. To distinguish petrogenic and pyrogenic sources of PAHs, we calculated the ratios of alkyl PAHs to parent PAHs: methylphenanthrenes to phenanthrene (MP/P), methylpyrenes+methylfluoranthenes to pyrene+fluoranthene (MPy/Py), and methylchrysenes+methylbenz[a]anthracenes to chrysene+benz[a]anthracene (MC/C). Analysis of source materials (crude oil, automobile exhaust, and coal and wood combustion products) gave thresholds of MP/P=0.4, MPy/Py=0.5, and MC/C=1.0 for exclusive combustion origin. All the combustion product samples had the ratios of alkyl PAHs to parent PAHs below these threshold values. Contributions of petrogenic and pyrogenic sources to the sedimentary PAHs were uneven among the homologs: the phenanthrene series had a greater petrogenic contribution, whereas the chrysene series had a greater pyrogenic contribution. All the Indian sediments showed a strong pyrogenic signature with MP/P approximately 0.5, MPy/Py approximately 0.1, and MC/C approximately 0.2, together with depletion of hopanes indicating intensive inputs of combustion products of coal and/or wood, probably due to the heavy dependence on these fuels as sources of energy. In contrast, sedimentary PAHs from all other tropical Asian cities were abundant in alkylated PAHs with MP/P approximately 1-4, MPy/Py approximately 0.3-1, and MC/C approximately 0.2-1.0, suggesting a ubiquitous input of petrogenic PAHs. Petrogenic contributions to PAH homologs varied among the countries: largest in Malaysia

  13. The formation of low-temperature sedimentary pyrite and its relationship with biologically-induced processes

    NASA Astrophysics Data System (ADS)

    Cavalazzi, B.; Agangi, A.; Barbieri, R.; Franchi, F.; Gasparotto, G.

    2014-09-01

    This contribution is an updated review on sedimentary pyrite and on its role in well-consolidated research topics, such as the biogeochemical cycles and the studies on sediment-hosted ore deposit studies, as well as new frontiers of research, such as astrobiology. Textural and compositional information preserved in sedimentary pyrite from sediment-hosted ore deposits has contributed to elucidate their environment of forzmation. In particular, the content of redox-sensitive elements such as Ni, Co, Mo, and V has implications for defining the syn- and post-sedimentary conditions. In addition, the stable isotope compositions are useful indicators of the pathways of both biogenic and abiogenic pyrite formation. Despite the longstanding research on pyrite and the mechanism of its formation, there are still significant gaps in our knowledge. In this nonexhaustive review, we briefly touch on different current aspects of research on sedimentary pyrite, exemplifying how sedimentary pyrite remains relevant to geoscientists, and becomes more and more relevant in understanding some basic aspects of knowledge, such as the origin of life and the search for extraterrestrial life, as well as aspect of classical applied science, such as the implications for ore deposition.

  14. SEDMIN - Microsoft Excel™ spreadsheet for calculating fine-grained sedimentary rock mineralogy from bulk geochemical analysis

    NASA Astrophysics Data System (ADS)

    Kackstaetter, Uwe R.

    2014-06-01

    Normative mineralogical calculations from bulk geochemistry of sedimentary rocks are problematic because of variable depositional environments, particle hydraulics and sedimentary source systems. The development of SEDMIN, a Microsoft Excel™ spreadsheet solution, is a practical attempt for a computational routine focusing specifically on smectite, chlorite, kaolinite, illite and the ambiguous sericite within various pelitic sedimentary lithologies. While in essence a mathematical approach, the use of statistical evaluation of empirical lithogeochemical data combined with modal analytical procedures yields reasonable geochemical associations, more precise chemical phases and revised procedural allotment paradigms. Thus, an algorithm using TiO2 as a key to the normative calculation of kaolinite is proposed. Incorporating additional parameters, such as LOI (Loss-on-ignition) in conjunction with carbon, sulfur, carbonate and sulfate, provides that clay phases can be more accurately determined than from bulk oxides alone. Even when presented with atypical sample data, the spreadsheet solution is able to accurately predict predominant clay minerals. Besides some drawbacks, the likely benefit from SEDMIN is the incorporation of results in classification norms and diagrams indicative of sedimentary lithologies. The "SEDMIN Sedimentary Mineral Calculator.xlsx" spreadsheet can be freely downloaded from http://earthscienceeducation.net/SEDMINSedimentaryMineralCalculator.xlsx.

  15. STEPPE: Supporting collaborative research and education on Earth's deep-time sedimentary crust.

    NASA Astrophysics Data System (ADS)

    Smith, D. M.

    2014-12-01

    STEPPE—Sedimentary geology, Time, Environment, Paleontology, Paleoclimate, and Energy—is a National Science Foundation supported consortium whose mission is to promote multidisciplinary research and education on Earth's deep-time sedimentary crust. Deep-time sedimentary crust research includes many specialty areas—biology, geography, ecology, paleontology, sedimentary geology, stratigraphy, geochronology, paleoclimatology, sedimentary geochemistry, and more. In fact, the diversity of disciplines and size of the community (roughly one-third of Earth-science faculty in US universities) itself has been a barrier to the formation of collaborative, multidisciplinary teams in the past. STEPPE has been working to support new research synergies and the development of infrastructure that will encourage the community to think about the big problems that need to be solved and facilitate the formation of collaborative research teams to tackle these problems. Toward this end, STEPPE is providing opportunities for workshops, working groups and professional development training sessions, web-hosting and database services and an online collaboration platform that facilitates interaction among participants, the sharing of documentation and workflows and an ability to push news and reports to group participants and beyond using social media tools. As such, STEPPE is working to provide an interactive space that will serve as both a gathering place and clearinghouse for information, allowing for broader integration of research and education across all STEPPE-related sub disciplines.

  16. The fate of diamondoids in coals and sedimentary rocks

    SciTech Connect

    Wei, Z.; Moldowan, J.M.; Jarvie, D.M.; Hill, R.

    2006-12-15

    Diamondoids were detected in the extracts of a series of coals and rocks varying in maturity, lithology, source input, and depositional environment. At the same maturity level, diamondoids are generally about a magnitude more abundant in source rocks than in coals. The concentrations of diamondoids are maturity dependent. However, while diamondoids become more abundant with the increasing thermal maturity, a diminution in diamondoid concentrations is observed at the maturity value of about R{sub o} = 4.0% in both coals and rocks. The occurrence of diamantane destruction at 550{sup o}C during pyrolysis suggests that diamondoids may be eventually destroyed at high temperatures in the Earth. Here we propose three main phases of diamondoid life in nature: diamondoid generation (phase I, R{sub o} < 1.1%), diamondoid generation and enrichment (phase II, 1.1% {le} R{sub o} {le}4.0%), and diamondoid destruction (phase III, R{sub o} > 4.0%).

  17. The fate of diamondoids in coals and sedimentary rocks

    USGS Publications Warehouse

    Wei, Z.; Moldowan, J.M.; Jarvie, D.M.; Hill, R.

    2006-01-01

    Diamondoids were detected in the extracts of a series of coals and rocks varying in maturity, lithology, source input, and depositional environment. At the same maturity level, diamondoids are generally about a magnitude more abundant in source rocks than in coals. The concentrations of diamondoids are maturity dependent. However, while diamondoids become more abundant with the increasing thermal maturity, a diminution in diamondoid concentrations is observed at the maturity value of about Ro = 4.0% in both coals and rocks. The occurrence of diamantane destruction at 550 ??C during pyrolysis suggests that diamondoids may be eventually destroyed at high temperatures in the Earth. Here we propose three main phases of diamondoid life in nature: diamondoid generation (phase I, Ro 4.0%). ?? 2006 Geological Society of America.

  18. Extending the Alternating Series Test

    ERIC Educational Resources Information Center

    Katsuura, Hidefumi

    2012-01-01

    Alternating series have the simplest of sign patterns. What about series with more complicated patterns? By inspecting the alternating series test closely, we find a theorem that applies to more complicated sign patterns, and beyond.

  19. Geochemistry and diagenesis of Miocene lacustrine siliceous sedimentary and pyroclastic rocks, Mytilinii basin, Samos Island, Greece

    USGS Publications Warehouse

    Stamatakis, M.G.; Hein, J.R.; Magganas, A.C.

    1989-01-01

    A Late Miocene non-marine stratigraphic sequence composed of limestone, opal-CT-bearing limestone, porcelanite, marlstone, diatomaceous marlstone, dolomite, and tuffite crops out on eastern Samos Island. This lacustrine sequence is subdivided into the Hora Beds and the underlying Pythagorion Formation. The Hora Beds is overlain by the clastic Mytilinii series which contains Turolian (Late Miocene) mammalian fossils. The lacustrine sequence contains volcanic glass and the silica polymorphs opal-A, opal-CT, and quartz. Volcanic glass predominantly occurs in tuffaceous rocks from the lower and upper parts of the lacustrine sequence. Opal-A (diatom frustules) is confined to layers in the upper part of the Hora Beds. Beds rich in opal-CT underlie those containing opal-A. The occurrence of opal-CT is extensive, encompassing the lower Hora Beds and the sedimentary rocks and tuffs of the Pythagorion Formation. A transition zone between the opal-A and opal-CT zones is identified by X-ray diffraction patterns that are intermediate between those of opal-CT and opal-A, perhaps due to a mixture of the two polymorphs. Diagenesis was not advanced enough for opal-CT to transform to quartz or for volcanic glass to transform to opal-C. Based on geochemical and mineralogical data, we suggest that the rate of diagenetic transformation of opal-A to opal-CT was mainly controlled by the chemistry of pore fluids. Pore fluids were characterized by high salinity, moderately high alkalinity, and high magnesium ion activity. These pore fluid characteristics are indicated by the presence of evaporitic salts (halite, sylvite, niter), high boron content in biogenic silica, and by dolomite in both the opal-A and opal-CT-bearing beds. The absence of authigenic K-feldspar, borosilicates, and zeolites also support these pore fluid characteristics. Additional factors that influenced the rate of silica diagenesis were host rock lithology and the relatively high heat flow in the Aegean region from

  20. Desiccation cracks in siliciclastic deposits: Microbial mat-related compared to abiotic sedimentary origin

    NASA Astrophysics Data System (ADS)

    Kovalchuk, Olga; Owttrim, George W.; Konhauser, Kurt O.; Gingras, Murray K.

    2017-01-01

    Siliciclastic sediment colonized by microbial mats yield a set of distinct sedimentary fabrics that are collectively called "mat-related structures (MRS)". In the rock record, versatile cracks are observed in biostabilized strata, but the mechanisms responsible for their formation remain debated. Microbially stabilized sediments produce desiccation cracks that serve as modern analogs for fossil microbial cracks. However, since both microbial mat shrinkage and clay shrinkage may contribute to the formation of these desiccation cracks, it is difficult to isolate the influence of the microbial mat on the resulting crack formation, distribution and morphology. To address this issue, we conducted a series of desiccation experiments that determine differences between microbially influenced desiccation cracks (i.e. biotic) and those formed in identical, but sterilized (i.e. abiotic) siliciclastic sediment. Three sediment mixtures were used: (1) very fine-sized sand, (2) mixed (ungraded) silt/clay, and (3) normally graded silt/clay. In all of the experiments, the water-rich microbial mat contracted substantially while drying, producing isolated pockets of shallow, but wide cracks, the distribution of which was controlled by heterogeneities in the mat structure and thickness variations of the mat. In the clay-poor substratum, the microbial mat was the only crack-forming mechanism, while in the clay-rich substrata (experiments 2 and 3) desiccation cracks were more strongly influenced by clay shrinkage. The abiotic clay-rich sediment produced a polygonal network of deep cracks intersecting at 90-120o junctions. In the biotic clay-rich experiments, the microbial mat modified these desiccation features by withstanding crack propagation or by producing curled-up crack polygon margins. Even though a microbial mat shrinks substantially with desiccation, its cohesive nature and heterogeneous distribution prevents the formation of a regular crack network, but its shallow penetration

  1. The Use of Ground Penetrating Radar to Exploring Sedimentary Ore In North-Central Saudi Arabia

    NASA Astrophysics Data System (ADS)

    Almutairi, Yasir; Almutair, Muteb

    2015-04-01

    Ground Penetrating Radar (GPR) is a non-destructive geophysical method that provides a continuous subsurface profile, without drilling. This geophysical technique has great potential in delineating the extension of bauxites ore in north-central Saudi Arabia. Bauxite is from types sedimentary ores. This study aim to evaluate the effectiveness of Ground Penetrating Radar (GPR) to illustrate the subsurface feature of the Bauxite deposits at some selected mining areas north-central Saudi Arabia. Bauxite is a heterogeneous material that consists of complex metals such as alumina and aluminum. An efficient and cost-effect exploration method for bauxite mine in Saudi Arabia is required. Ground penetrating radar (GPR) measurements have been carrying out along outcrop in order to assess the potential of GPR data for imaging and characterising different lithological facies. To do so, we have tested different antenna frequencies to acquire the electromagnetic signals along a 90 m profile using the IDS system. This system equipped with a 25 MHz antenna that allows investigating the Bauxite layer at shallow depths where the clay layers may existed. Therefore, the 25 MHz frequency antenna has been used in this study insure better resolution of the subsurface and to get more penetration to image the Bauxite layer. After the GPR data acquisition, this data must be processed in order to be more easily visualized and interpreted. Data processing was done using Reflex 6.0 software. A series of tests were carried out in frequency filtering on a sample of radar sections, which was considered to better represent the entire set of data. Our results indicated that the GPR profiling has a very good agreement for mapping the bauxite layer depth at range of 7 m to 11 m. This study has emphasized that the high-resolution GPR method is the robust and cost-effect technique to map the Bauxite layer. The exploration of Bauxite resource using the GPR technique could reduce the number of holes to

  2. Eutrophication signals in the sedimentary record of dinoflagellate cysts in coastal waters

    NASA Astrophysics Data System (ADS)

    Dale, Barrie

    2009-01-01

    A brief review is presented of the current status of eutrophication signals from the sedimentary records of dinoflagellate cysts in coastal waters, particularly of NW Europe. There is a dearth of the multi-decadal time series data from plankton needed to document eutrophication, and the cysts may provide an alternative source of information. Two different eutrophication signals have been described so far from cyst records: 1) from the Oslofjord, comprising a marked increase in total cyst concentrations (interpreted as probably reflecting increased phytoplankton productivity), with Lingulodinium polyedrum cysts accounting for most of the increase (interpreted as a species particularly benefiting from added nutrients from cultural eutrophication in late summer when nutrients otherwise may be limiting); and 2) the heterotroph signal, from several other Norwegian fjords and Tokyo Bay, Japan, involving both cases of increased cyst concentrations and others with no particular increase, but with a marked proportional increase in cysts of heterotrophic species (interpreted as reflecting increased diatoms and possibly other prey for the heterotrophic dinoflagellates and/or more unfavourable conditions for autotrophs, e.g. from shading). These signals should be used critically, and there is a particular need to distinguish between eutrophication signals and climate signals that may be co-occurring at a given time. Work by various authors has generally supported the concept of these cyst-based signals since they were first published, including both further records from cored sediments from other parts of the world and studies relating cyst distributions in surface sediments to gradients of pollution and nutrients from sewage discharge. Recent, unpublished work by Dale and Sætre, linked cyst signals in cored sediments to the timing of collapse of local fisheries at different times within the past fifty years in four fjord systems along the Norwegian Skagerrak coast

  3. Sedimentary Rocks of 8oN, 7oW

    NASA Technical Reports Server (NTRS)

    2004-01-01

    11 September 2004 An impact crater in western Arabia Terra at 8oN, 7oW, exhibits some of the most fantastic sedimentary rock outcrops on Mars. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example. The crater interior has hundreds of sedimentary rock layers, each of a similar thickness and similar physical properties. The similarities between beds and their repeated nature have been used to suggest that the crater was once the site of a lake. Today, the sedimentary rocks are eroded and dark, windblown sand covers some of them. Faults cut and offset beds in some places. The image covers an area approximately 3 km (1.9 mi) across and is illuminated by sunlight from the left/lower left.

  4. An evaluation of multiband photography for rock discrimination. [sedimentary rocks of Front Range, Colorado

    NASA Technical Reports Server (NTRS)

    Lee, K. (Principal Investigator); Raines, G. L.

    1974-01-01

    The author has identified the following significant results. With the advent of ERTS and Skylab satellites, multiband imagery and photography have become readily available to geologists. The ability of multiband photography to discriminate sedimentary rocks was examined. More than 8600 in situ measurements of band reflectance of the sedimentary rocks of the Front Range, Colorado, were acquired. Statistical analysis of these measurements showed that: (1) measurements from one site can be used at another site 100 miles away; (2) there is basically only one spectral reflectance curve for these rocks, with constant amplitude differences between the curves; and (3) the natural variation is so large that at least 150 measurements per formation are required to select best filters. These conclusions are supported by subjective tests with aerial multiband photography. The designed multiband photography concept for rock discrimination is not a practical method of improving sedimentary rock discrimination capabilities.

  5. Palynostratigraphy of the Erkovtsy field of brown coal (the Zeya-Bureya sedimentary basin)

    SciTech Connect

    Kezina, T.V.; Litvinenko, N.D.

    2007-08-15

    The Erkovtsy brown coal field in the northwestern Zeya-Bureya sedimentary basin (129-130{sup o}E, 46-47{sup o}N) is structurally confined to southern flank of the Mesozoic-Cenozoic Belogor'e depression. The verified stratigraphic scheme of the coalfield sedimentary sequence is substantiated by palynological data on core samples from 18 boreholes sampled in the course of detailed prospecting and by paleobotanical analysis of sections in the Yuzhnyi sector of the coalfield (data of 1998 by M.A. Akhmetiev and S.P. Manchester). Sections of the Erkovtsy, Arkhara-Boguchan, and Raichikha brown-coal mines are correlated. Stratigraphic subdivisions distinguished in the studied sedimentary succession are the middle and upper Tsagayan subformations (the latter incorporating the Kivda Beds), Raichikha, Mukhino, Buzuli, and Sazanka formations.

  6. Dynamic Study on Fracture Problems in Viscoelastic Sedimentary Rocks Using the Numerical Manifold Method

    NASA Astrophysics Data System (ADS)

    Wu, Zhijun; Wong, Louis Ngai Yuen; Fan, Lifeng

    2013-11-01

    The viscoelastic deformation behavior of a sedimentary rock under different loading rates is numerically modeled and investigated by the numerical manifold method (NMM). By incorporating a modified 3-element viscoelastic constitutive mode in the NMM, crack initiation and propagation criteria, and crack identification and evolution techniques, the effects of the loading rates on the cracking behavior of a sedimentary rock, such as crack open displacement, crack sliding displacement, crack initiation, crack propagation and final failure mode, are successfully modeled. The numerical results reveal that under a high loading rate (>1,000 MPa/s), due to the viscoelastic property of the sedimentary rock, not only the structural behavior deviates from that of elastic model, but also different cracking processes and final failure modes are obtained.

  7. Sedimentary basin analysis using airborne gravity data: a case study from the Bohai Bay Basin, China

    NASA Astrophysics Data System (ADS)

    Li, Wenyong; Liu, Yanxu; Zhou, Jianxin; Zhou, Xihua; Li, Bing

    2016-11-01

    In this paper, we discuss the application of an airborne gravity survey to sedimentary basin analysis. Using high-precision airborne gravity data constrained by drilling and seismic data from the Bohai Bay Basin in eastern China, we interpreted faults, structural elements, sedimentary thickness, structural styles and local structures (belts) in the central area of the Basin by the wavelet transform method. Subsequently, these data were subtracted from the Bouguer gravity to calculate the residual gravity anomalies. On this basis, the faults were interpreted mainly by linear zones of high gravity gradients and contour distortion, while the sedimentary thicknesses were computed by the Euler deconvolution. The structural styles were identified by the combination of gravity anomalies and the local structures interpreted by the first vertical derivative of the residual gravity. The results showed evidence for seven faults, one sag and ten new local structure belts.

  8. Organic solvent alteration of hydraulic properties of sedimentary rocks of low permeability: a review

    SciTech Connect

    Sklarew, D.S.

    1985-05-01

    A review of the current literature on hydrophysical interactions of organic solutes with sedimentary rocks of low permeability is presented. The motivation was the premise that low permeability rocks may act as secondary (aquifer) barriers for the containment of hazardous organic wastes, thus preventing these wastes from contaminating the groundwater. However, this premise may be incorrect if organic wastes can affect the hydraulic conductivity of these rocks. The results indicate that very little work has been done concerning interactions of organics with consolidated subsurface materials. Available information on three related topics was summarized: the effect of organic compounds on the hydrophysical properties of clays, case studies concerning the interactions of organic compounds with clays and sedimentary rocks, and the effect of shales on inorganic transport. These studies give an indication of some research areas that need to be explored with regard to the effect of organic compounds on the hydrophysical properties of sedimentary rocks; these research needs are briefly summarized. 42 refs.

  9. Regional-scale analysis of the geothermal regime in the western Canada sedimentary basin

    SciTech Connect

    Bachu, S. ); Burwash, R.A. )

    1991-01-01

    This paper reports that radiogenic heat generation at the top of the crystalline Precambrian basement underneath the Western Canada Sedimentary Basin is highly variable, on average higher than for the exposed Canadian Shield, and reflects the basement tectonic structure. The areal distribution of the geothermal gradient across the sediments shows a regional-scale northerly increase, with intermediate- and local-state features correlating with anomalies in heat generation at the top of the basement. Only in the northeast and southeast corners of the basin can high geothermal gradients not be explained by heat generation; there they may be caused by convective fluid flow effects. The temperature distribution at the base of the sediments is highly correlated with the thickness of the sedimentary cover and reflects major topographic and basement features. Overall, the characteristics of the geothermal regime in the Western Canada Sedimentary Basin are indicative of a conduction dominated system.

  10. Hydrogeologic framework of sedimentary deposits in six structural basins, Yakima River basin, Washington

    USGS Publications Warehouse

    Jones, M.A.; Vaccaro, J.J.; Watkins, A.M.

    2006-01-01

    The hydrogeologic framework was delineated for the ground-water flow system of the sedimentary deposits in six structural basins in the Yakima River Basin, Washington. The six basins delineated, from north to south are: Roslyn, Kittitas, Selah, Yakima, Toppenish, and Benton. Extent and thicknesses of the hydrogeologic units and total basin sediment thickness were mapped for each basin. Interpretations were based on information from about 4,700 well records using geochemical, geophysical, geologist's or driller's logs, and from the surficial geology and previously constructed maps and well interpretations. The sedimentary deposits were thickest in the Kittitas Basin reaching a depth of greater than 2,000 ft, followed by successively thinner sedimentary deposits in the Selah basin with about 1,900 ft, Yakima Basin with about 1,800 ft, Toppenish Basin with about 1,200 ft, Benton basin with about 870 ft and Roslyn Basin with about 700 ft.

  11. Sedimentary Mounds on Mars: Tracing Present-day Formation Processes into the Past

    NASA Technical Reports Server (NTRS)

    Niles, P. B.; Michalski, J.; Edwards, C. S.

    2014-01-01

    High resolution photography and spectroscopy of the martian surface (MOC, HiRISE) from orbit has revolutionized our view of Mars with one and revealed spectacular views of finely layered sedimentary materials throughout the globe [1]. Some of these sedimentary deposits are 'mound' shaped and lie inside of craters (Fig 1). Crater mound deposits are found throughout the equatorial region, as well as ice-rich deposits found in craters in the north and south polar region [2-4]. Despite their wide geographical extent and varying volatile content, the 'mound' deposits have a large number of geomorphic and structural similarities that suggest they formed via equivalent processes. Thus, modern depositional processes of ice and dust can serve as an invaluable analog for interpreting the genesis of ancient sedimentary mound deposits.

  12. Sedimentary 12-n-Propylcholestanes, Molecular Fossils Diagnostic of Marine Algae.

    PubMed

    Moldowan, J M; Fago, F J; Lee, C Y; Jacobson, S R; Watt, D S; Slougui, N E; Jeganathan, A; Young, D C

    1990-01-19

    Certain C(30)-steranes have been used for identifying sedimentary rocks and crude oils derived from organic matter deposited in marine environments. Analysis of a C(30)-sterane from Prudhoe Bay oil indicates that these C(30)-steranes are 24-n-propylcholestanes that apparently are derived from precursor sterols 24-n-propylidene-cholesterols and 24-n-propylcholesterol. These widely occurring sterols are biochemically synthesized in modern oceans by members of an order (Sarcinochrysidales) of chrysophyte algae. These data thus imply that C(30)-sterane biomarkers in sedimentary rocks and crude oils have a marine origin. Screening of a few organic-rich sedimentary rocks and oils from throughout the Phanerozoic suggests that these C(30)-steranes first appeared and, therefore, their source algae evolved between Early Ordovician and Devonian.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  14. Geology, Geochemistry and Geophysics of Sedimentary Rock-Hosted Au Deposits in P.R. China

    USGS Publications Warehouse

    Peters, Stephen G.

    2002-01-01

    This is the second report concerning results of a joint project between the U.S. Geological Survey and the Tianjin Geological Academy to study sedimentary rock-hosted Au deposits in P.R. China. Since the 1980s, Chinese geologists have devoted a large-scale exploration and research effort to the deposits. As a result, there are more than 20 million oz of proven Au reserves in sedimentary rock-hosted Au deposits in P.R. China. Additional estimated and inferred resources are present in over 160 deposits and occurrences, which are undergoing exploration. This makes China second to Nevada in contained ounces of Au in Carlin-type deposits. It is likely that many of the Carlin-type Au ore districts in China, when fully developed, could have resource potential comparable to the multi-1,000-tonne Au resource in northern Nevada. The six chapters of this report describe sedimentary rock-hosted Au deposits that were visited during the project. Chapters 1 and 2 provide an overview of sedimentary rock-hosted Au deposits and Carlin-type Au deposits and also provide a working classification for the sedimentary rock-hosted Au deposits. Chapters 3, 4, and 5 provide descriptions that were compiled from the literature in China in three main areas: the Dian-Qian-Gui, the Qinling fold belt, and Middle-Lower Yangtze River areas. Chapter 6 contains a weights-of-evidence (WofE), GIS-based mineral assessment of sedimentary rock-hosted Au deposits in the Qinling fold belt and Dian-Qian-Gui areas. Appendices contain scanned aeromagnetic (Appendix I) and gravity (Appendix II) geophysical maps of south and central China. Data tables of the deposits (Appendix III) also are available in the first report as an interactive database at http://geopubs.wr.usgs.gov/open-file/of98-466/. Geochemical analysis of ore samples from the deposits visited are contained in Appendix IV.

  15. The Influence of Source Biases on Sedimentary Leaf Waxes and Their Stable Isotope Compositions

    NASA Astrophysics Data System (ADS)

    Diefendorf, A. F.; Freimuth, E. J.; Lowell, T. V.; Wiles, G. C.

    2015-12-01

    Leaf waxes and their carbon (δ13C) and hydrogen (δD) isotopic compositions are an important tool to understand past changes in paleoclimate and paleovegetation. Important recent advances in our understanding about the isotopic signal preserved in sedimentary leaf waxes have been inferred from studies made on individual modern plants. However, paleoreconstructions are based on sedimentary leaf waxes, which reflect mixing between multiple sources, such as ablated leaf waxes from nearby or from afar, wind blown leaf litter, and riverine transported leaf waxes. Each of these sources integrates leaf waxes from different species and growth forms, likely resulting in source-specific taphonomic biases on sedimentary leaf wax isotopes. To better understand source biases in sedimentary leaf waxes, we investigated n-alkanes and n-alkanoic acids and their carbon and hydrogen isotopes in vegetation and lake sediments at Brown's Lake and Bog, a 'simple' forested closed-basin lake in northeastern Ohio. Interestingly, we found that tree n-alkane δD varied substantially during the growing season, broadly tracking changes in source water composition. However, δD values of n-alkanes in the tree leaf litter did not match that of the most recent sedimentary n-alkanes. Instead, surface sediment n-alkane δD more closely matched that of the woody shrubs and grasses growing right around the lake. n-Alkanoic acid data is forthcoming. We are currently exploring lake sediment n-alkane accumulation rates against midwestern flux rates of wind blown leaf waxes from afar. Our preliminary results suggest that although studies made on individual leaves are indeed important, we may need to consider additional leaf wax sources that potentially influence sedimentary archives.

  16. Ecosystem disturbances in Central European spruce forests: a multi-proxy integration of dendroecology and sedimentary records

    NASA Astrophysics Data System (ADS)

    Clear, Jennifer; Chiverrell, Richard; Kunes, Petr; Svoboda, Miroslav; Boyle, John

    2016-04-01

    Disturbance dynamics in forest ecosystems shows signs of perturbation in the light of changing climate regimes with the frequency and intensity of events (e.g. pathogens in North America and Central Europe) amplified, becoming more frequent and severe. The montane Norway spruce (Picea abies) dominated forests of Central Europe are a niche habitat and environment; situated outside their natural boreal distribution (e.g. Fenno-Scandinavia). These communities are at or near their ecological limits and are vulnerable to both short term disturbances (e.g. fire, windstorm and pathogens) and longer-term environmental change (e.g. climate induced stress and changing disturbance patterns). Researches have linked negative impacts on spruce forest with both wind disturbance (wind-throw) and outbreaks of spruce bark beetle (Ips typographus), and there is growing evidence for co-association with wind damage enhancing pathogenic outbreaks. Examples include: in the Bohemian Forest (Czech Republic) the mid-1990s spruce bark beetle outbreak and the 2007 windstorm and subsequent bark beetle outbreak. In the High Tatra Mountains (Slovakia) there is a further co-association of forest disturbance with windstorms (2004 and 2014) and an ongoing bark beetle outbreak. The scale and severity of these recent outbreaks of spruce bark beetle are unprecedented in the historical forest records. Here, findings from ongoing research developing and integrating data from dendroecological, sedimentary palaeoecological and geochemical time series to develop a longer-term perspective on forest dynamics in these regions. Tree-ring series from plots or forest stands (>500) are used alongside lake (5) and forest hollow (3) sediments from the Czech and Slovak Republics to explore the local, regional and biogeographical scale of forest disturbances. Dendroecological data showing tree-ring gap recruitment and post-suppression growth release highlight frequent disturbance events focused on tree or forest

  17. Sequences, Series, and Mathematica.

    ERIC Educational Resources Information Center

    Mathews, John H.

    1992-01-01

    Describes how the computer algebra system Mathematica can be used to enhance the teaching of the topics of sequences and series. Examines its capabilities to find exact, approximate, and graphically generated approximate solutions to problems from these topics and to understand proofs about sequences. (MDH)

  18. Building Alliances Series: Education

    ERIC Educational Resources Information Center

    Brady, Cecilia

    2009-01-01

    Public-private partnerships done right are a powerful tool for development, providing enduring solutions to some of the greatest challenges. To help familiarize readers with the art of alliance building, the Global Development Alliance (GDA) office has created a series of practical guides that highlight proven practices in partnerships,…

  19. Diamond Anniversary Lecture Series.

    ERIC Educational Resources Information Center

    Adams, Dewey A.; And Others

    This document contains the texts of four lectures that were presented as part of a series commemorating the 75th anniversary of Ohio State University's Department of Agricultural Education. The first lecture, "The Conceptualization Process and Vocational Education Management," (Dewey A. Adams) discusses a five-step management behavior approach for…

  20. Computer Series, 54.

    ERIC Educational Resources Information Center

    Moore, John W., Ed.

    1984-01-01

    Describes graphical solutions of equations for stirred-tank reactors in series; data management software for producing and searching customized mass spectral libraries; least squares and chromatography programs; a low-cost data acquisition system for Apple microcomputers; nuclear magnetic resonance interpretation with graphics; chemical bonding…

  1. Discrimination. Opposing Viewpoints Series.

    ERIC Educational Resources Information Center

    Williams, Mary E., Ed.

    Books in the Opposing Viewpoints series challenge readers to question their own opinions and assumptions. By reading carefully balanced views, readers confront new ideas on the topic of interest. The Civil Rights Act of 1964, which prohibited job discrimination based on age, race, religion, gender, or national origin, provided the groundwork for…

  2. Poverty. Opposing Viewpoints Series.

    ERIC Educational Resources Information Center

    Leone, Bruno, Ed.

    Books in the Opposing Viewpoints Series present debates about current issues that can be used to teach critical reading and thinking skills. The varied opinions in each collection explore aspects of a social, cultural, or political issue. A great deal of money has been spent in this country to eradicate poverty, but the problem remains. Some…

  3. Gangs. Opposing Viewpoints Series.

    ERIC Educational Resources Information Center

    Cozic, Charles P., Ed.

    Books in the Opposing Viewpoints Series present debates about current issues that can be used to teach critical reading and thinking skills. The variety of opinions expressed in this collection of articles and book excerpts explore many aspects of juvenile gangs. Some youths join gangs of their own free choice, to satisfy ego or greed. Others are…

  4. Lower GI Series

    MedlinePlus

    ... may ask the person to change position several times to evenly coat the large intestine with the barium • if the health care provider has ordered a double-contrast lower GI series, the radiologist will inject air through the tube ...

  5. Parent's Journal. [Videotape Series].

    ERIC Educational Resources Information Center

    1999

    Parent's Journal is a set of 16 videotapes for parents of prenatal, infant, and toddler-age children, created by the Alaska Native Home Base Video Project of the Tlingit and Haida Head Start Program. This series offers culturally relevant solutions to the challenges of parenting, drawing on the life stories and experiences of capable mothers and…

  6. Family Feathers. [Videotape Series].

    ERIC Educational Resources Information Center

    1999

    Family Feathers is a set of 18 videotapes for parents of preschool children, created by the Alaska Native Home Base Video Project of the Tlingit and Haida Head Start Program. This series offers culturally relevant solutions to the challenges of parenting, drawing on practical advice from Tlingit and Haida parents, wisdom from elders, and some of…

  7. Themes. Informal Education Series.

    ERIC Educational Resources Information Center

    Kessens, Rosanne

    Part of the larger Informal Education Series, this publication brings together many of the materials prepared by Rosanne Kessens for teachers and parents involved in Follow Through settings. Contents first explore theme development as an integrated approach to learning and then describe strategies for planning themes. Subsequent materials offer…

  8. Estimating tectonic history through basin simulation-enhanced seismic inversion: geoinfomatics for sedimentary basins

    NASA Astrophysics Data System (ADS)

    Tandon, Kush; Tuncay, Kagan; Hubbard, Kyle; Comer, John; Ortoleva, Peter

    2004-01-01

    A data assimilation approach is demonstrated whereby seismic inversion is both automated and enhanced using a comprehensive numerical sedimentary basin simulator to study the physics and chemistry of sedimentary basin processes in response to geothermal gradient in much greater detail than previously attempted. The approach not only reduces costs by integrating the basin analysis and seismic inversion activities to understand the sedimentary basin evolution with respect to geodynamic parameters-but the technique also has the potential for serving as a geoinfomatics platform for understanding various physical and chemical processes operating at different scales within a sedimentary basin. Tectonic history has a first-order effect on the physical and chemical processes that govern the evolution of sedimentary basins. We demonstrate how such tectonic parameters may be estimated by minimizing the difference between observed seismic reflection data and synthetic ones constructed from the output of a reaction, transport, mechanical (RTM) basin model. We demonstrate the method by reconstructing the geothermal gradient. As thermal history strongly affects the rate of RTM processes operating in a sedimentary basin, variations in geothermal gradient history alter the present-day fluid pressure, effective stress, porosity, fracture statistics and hydrocarbon distribution. All these properties, in turn, affect the mechanical wave velocity and sediment density profiles for a sedimentary basin. The present-day state of the sedimentary basin is imaged by reflection seismology data to a high degree of resolution, but it does not give any indication of the processes that contributed to the evolution of the basin or causes for heterogeneities within the basin that are being imaged. Using texture and fluid properties predicted by our Basin RTM simulator, we generate synthetic seismograms. Linear correlation using power spectra as an error measure and an efficient quadratic

  9. Displacement propagators of brine flowing within different types of sedimentary rock.

    PubMed

    Verganelakis, Dimitris A; Crawshaw, John; Johns, Michael L; Mantle, Michael D; Scheven, Ulrich; Sederman, Andrew J; Gladden, Lynn F

    2005-02-01

    This paper explores the correlation between different microstructural characteristics of porous sedimentary rocks and the flow properties of a Newtonian infiltrating fluid. Preliminary results of displacement propagator measurements of brine solution flowing through two types of sedimentary rock cores are reported. The two types of rocks, Bentheimer and Portland, are characterized by different porosities, pore-size distributions and permeabilities. Propagators have been measured for brine flow rates of 1 and 5 ml/min. Significant differences are seen between the propagators recorded for the two rocks, and these are related to the spatial distribution of porosity within these porous media.

  10. Atmospheric methane from organic carbon mobilization in sedimentary basins — The sleeping giant?

    NASA Astrophysics Data System (ADS)

    Kroeger, K. F.; di Primio, R.; Horsfield, B.

    2011-08-01

    The mass of organic carbon in sedimentary basins amounts to a staggering 10 16 t, dwarfing the mass contained in coal, oil, gas and all living systems by ten thousand-fold. The evolution of this giant mass during subsidence and uplift, via chemical, physical and biological processes, not only controls fossil energy resource occurrence worldwide, but also has the capacity for driving global climate: only a tiny change in the degree of leakage, particularly if focused through the hydrate cycle, can result in globally significant greenhouse gas emissions. To date, neither climate models nor atmospheric CO 2 budget estimates have quantitatively included methane from thermal or microbial cracking of sedimentary organic matter deep in sedimentary basins. Recent estimates of average low latitude Eocene surface temperatures beyond 30 °C require extreme levels of atmospheric CO 2. Methane degassing from sedimentary basins may be a mechanism to explain increases of atmospheric CO 2 to values as much as 20 times higher than pre-industrial values. Increased natural gas emission could have been set in motion either by global tectonic processes such as pulses of activity in the global alpine fold belt, leading to increased basin subsidence and maturation rates in the prolific Jurassic and Cretaceous organic-rich sediments, or by increased magmatic activity such as observed in the northern Atlantic around the Paleocene-Eocene boundary. Increased natural gas emission would have led to global warming that was accentuated by long lasting positive feedback effects through temperature transfer from the surface into sedimentary basins. Massive gas hydrate dissociation may have been an additional positive feedback factor during hyperthermals superimposed on long term warming, such as the Paleocene-Eocene Thermal Maximum (PETM). As geologic sources may have contributed over one third of global atmospheric methane in pre-industrial time, variability in methane flux from sedimentary

  11. Chemical Composition of Martian Soil and Rocks: Complex Mixing and Sedimentary Transport

    NASA Technical Reports Server (NTRS)

    McLennan, Scott M.

    2000-01-01

    Chemical compositions of Martian soil and rocks indicate complex mixing relationships. Mixing of rock and soil clearly takes place and explains some of the chemical variation because sulfur, chlorine, magnesium, and perhaps iron are positively correlated due to their control from a secondary 'sedimentary' mineralogy (e.g., Mg- and possibly Fe-sulfate; Fe-oxides) that is present within the soils. Certain deviations from simple soil-rock mixing are consistent with mineralogical fractionation of detrital iron and titanium oxides during sedimentary transport.

  12. Estimating tectonic history through basin simulation-enhanced seismic inversion: Geoinformatics for sedimentary basins

    USGS Publications Warehouse

    Tandon, K.; Tuncay, K.; Hubbard, K.; Comer, J.; Ortoleva, P.

    2004-01-01

    A data assimilation approach is demonstrated whereby seismic inversion is both automated and enhanced using a comprehensive numerical sedimentary basin simulator to study the physics and chemistry of sedimentary basin processes in response to geothermal gradient in much greater detail than previously attempted. The approach not only reduces costs by integrating the basin analysis and seismic inversion activities to understand the sedimentary basin evolution with respect to geodynamic parameters-but the technique also has the potential for serving as a geoinfomatics platform for understanding various physical and chemical processes operating at different scales within a sedimentary basin. Tectonic history has a first-order effect on the physical and chemical processes that govern the evolution of sedimentary basins. We demonstrate how such tectonic parameters may be estimated by minimizing the difference between observed seismic reflection data and synthetic ones constructed from the output of a reaction, transport, mechanical (RTM) basin model. We demonstrate the method by reconstructing the geothermal gradient. As thermal history strongly affects the rate of RTM processes operating in a sedimentary basin, variations in geothermal gradient history alter the present-day fluid pressure, effective stress, porosity, fracture statistics and hydrocarbon distribution. All these properties, in turn, affect the mechanical wave velocity and sediment density profiles for a sedimentary basin. The present-day state of the sedimentary basin is imaged by reflection seismology data to a high degree of resolution, but it does not give any indication of the processes that contributed to the evolution of the basin or causes for heterogeneities within the basin that are being imaged. Using texture and fluid properties predicted by our Basin RTM simulator, we generate synthetic seismograms. Linear correlation using power spectra as an error measure and an efficient quadratic

  13. The Lower Triassic sedimentary and carbon isotope records from Tulong (South Tibet) and their significance for Tethyan palaeoceanography

    NASA Astrophysics Data System (ADS)

    Brühwiler, Thomas; Goudemand, Nicolas; Galfetti, Thomas; Bucher, Hugo; Baud, Aymon; Ware, David; Hermann, Elke; Hochuli, Peter A.; Martini, Rossanna

    2009-12-01

    The Lower Triassic sedimentary and carbonate/organic carbon isotope records from the Tulong area (South Tibet) are documented in their integrality for the first time. New age control is provided by ammonoid and conodont biostratigraphy. The basal Triassic series consists of Griesbachian dolomitic limestones, similar to the Kathwai Member in the Salt Range (Pakistan) and to the Otoceras Beds in Spiti (India). The overlying thin-bedded limestones of Dienerian age strongly resemble the Lower Ceratite Limestone of the Salt Range. They are followed by a thick series of dark green, silty shales of Dienerian-early Smithian age without fauna that strikingly resemble the Ceratite Marls of the Salt Range. This interval is overlain by thin-bedded, light grey fossil-rich limestones of middle to late Smithian age, resembling the Upper Ceratite Limestone of the Salt Range. These are followed by a shale interval of early Spathian age that has no direct counterpart in other Tethyan sections. Carbonate production resumes during the late early and middle Spathian with the deposition of red, bioclastic nodular limestone ("Ammonitico Rosso" type facies). Apart from its colour this facies is similar to the one of the Niti Limestone in Spiti and of the Spathian nodular limestone in Guangxi (South China). As in other Tethyan localities such as Spiti, the early-middle Anisian part of the Tulong section is strongly condensed and is characterized by grey, thin-bedded limestones with phosphatized ammonoids. As for many other Tethyan localities the carbon isotope record from Tulong is characterized by a late Griesbachian-Dienerian positive δ13C carb excursion (2‰), and a very prominent positive excursion (5‰) at the Smithian-Spathian boundary, thus confirming the well-documented perturbations of the global carbon cycle following the Permian-Triassic mass extinction event.

  14. The stable hydrogen isotopic composition of sedimentary plant waxes as quantitative proxy for rainfall in the West African Sahel

    NASA Astrophysics Data System (ADS)

    Niedermeyer, Eva M.; Forrest, Matthew; Beckmann, Britta; Sessions, Alex L.; Mulch, Andreas; Schefuß, Enno

    2016-07-01

    Various studies have demonstrated that the stable hydrogen isotopic composition (δD) of terrestrial leaf waxes tracks that of precipitation (δDprecip) both spatially across climate gradients and over a range of different timescales. Yet, reconstructed estimates of δDprecip and corresponding rainfall typically remain largely qualitative, due mainly to uncertainties in plant ecosystem net fractionation, relative humidity, and the stability of the amount effect through time. Here we present δD values of the C31n-alkane (δDwax) from a marine sediment core offshore the Northwest (NW) African Sahel covering the past 100 years and overlapping with the instrumental record of rainfall. We use this record to investigate whether accurate, quantitative estimates of past rainfall can be derived from our δDwax time series. We infer the composition of vegetation (C3/C4) within the continental catchment area by analysis of the stable carbon isotopic composition of the same compounds (δ13Cwax), calculated a net ecosystem fractionation factor, and corrected the δDwax time series accordingly to derive δDprecip. Using the present-day relationship between δDprecip and the amount of precipitation in the tropics, we derive quantitative estimates of past precipitation amounts. Our data show that (a) vegetation composition can be inferred from δ13Cwax, (b) the calculated net ecosystem fractionation represents a reasonable estimate, and (c) estimated total amounts of rainfall based on δDwax correspond to instrumental records of rainfall. Our study has important implications for future studies aiming to reconstruct rainfall based on δDwax; the combined data presented here demonstrate that it is feasible to infer absolute rainfall amounts from sedimentary δDwax in tandem with δ13Cwax in specific depositional settings.

  15. Series elastic actuators

    NASA Astrophysics Data System (ADS)

    Williamson, Matthew M.

    1995-01-01

    This thesis presents the design, construction, control and evaluation of a novel for controlled actuator. Traditional force controlled actuators are designed from the premise that 'Stiffer is better'. This approach gives a high bandwidth system, prone to problems of contact instability, noise, and low power density. The actuator presented in this thesis is designed from the premise that 'Stiffness isn't everything'. The actuator, which incorporates a series elastic element, trades off achievable bandwidth for gains in stable, low noise force control, and protection against shock loads. This thesis reviews related work in robot force control, presents theoretical descriptions of the control and expected performance from a series elastic actuator, and describes the design of a test actuator constructed to gather performance data. Finally the performance of the system is evaluated by comparing the performance data to theoretical predictions.

  16. Interdisciplinary Distinguished Seminar Series

    DTIC Science & Technology

    2014-08-29

    information sciences , nanotechnology, mathematics, and physics. The list of speakers included leaders of the respective fields from the US and abroad...and engineering, computer science and mathematics. The list of speakers included leaders of the respective fields from the US and abroad. All the...summary, this funded Interdisciplinary Seminar Series have not only brought the best in the disciplines of Information Science and Systems, but as an

  17. A New Unusual Ice-induced Sedimentary Structure: the Silt Mushroom.

    PubMed

    Jianhua, Zhong; Liangtian, Ni; Ningliang, Sun; Chuang, Liu; Bing, Hao; Mengchun, Cao; Xin, Chen; Ke, Luo; Shengxin, Liu; Leitong, Huang; Guanqun, Yang; Shaojie, Wang; Feifei, Su; Xuejing, He; Yanqiu, Xue

    2016-11-11

    Upon channel bars or point bars within the lows of the Yellow River, a new sedimentary structure, named 'silt mushroom', has been observed. The process of their formation is interpreted to be via the ice process. The name, the silt mushroom comes from their figurative form. This is because they look somewhat similar to mushroom's in size and shape; being in the range of 1 to 10 cm in diameter, with the medium 3-5 cm, and on average 10 cm in height, occuring generally in groups, and occasionally in isolation in relatively soft silt. They develop in the transition from winter to spring, and are convincingly related to ice processes. Ice-induced silt mushrooms are best examined in association with the many other newly discovered ice-induced sedimentary structures (over 20 kinds). Clearly, up to now, ice processes have been significantly underestimated. With the substantial discovery of the ice-induced silt mushroom, it opens up new questions. This is because its structure mirrors the same sedimentary structures found in rocks, questioning their genesis, and sedimentary environment analysis. This achievement is significant not only in sedimentology, but also in palaeogeography, palaeoclimate, geological engineering, hydraulics and fluviology.

  18. Highly Shocked Low Density Sedimentary Rocks from the Haughton Impact Structure, Devon Island, Nunavut, Canada

    NASA Technical Reports Server (NTRS)

    Osinski, G. R.; Spray, J. G.

    2001-01-01

    We present the preliminary results of a detailed investigation of the shock effects in highly shocked, low density sedimentary rocks from the Haughton impact structure. We suggest that some textural features can be explained by carbonate-silicate immiscibility. Additional information is contained in the original extended abstract.

  19. Areal distribution of sedimentary facies determined from seismic facies analysis and models of modern depositional systems

    SciTech Connect

    Seramur, K.C.; Powell, R.D.; Carpenter, P.J.

    1988-02-01

    Seismic facies analysis was applied to 3.5-kHz single-channel analog reflection profiles of the sediment fill within Muir Inlet, Glacier Bay, southeast Alaska. Nine sedimentary facies have been interpreted from seven seismic facies identified on the profiles. The interpretations are based on reflection characteristics and structural features of the seismic facies. The following reflection characteristics and structural features are used: reflector spacing, amplitude and continuity of reflections, internal reflection configurations, attitude of reflection terminations at a facies boundary, body geometry of a facies, and the architectural associations of seismic facies within each basin. The depositional systems are reconstructed by determining the paleotopography, bedding patterns, sedimentary facies, and modes of deposition within the basin. Muir Inlet is a recently deglaciated fjord for which successive glacier terminus positions and consequent rates of glacial retreat are known. In this environment the depositional processes and sediment characteristics vary with distance from a glacier terminus, such that during a retreat a record of these variations is preserved in the aggrading sediment fill. Sedimentary facies within the basins of lower Muir Inlet are correlated with observed depositional processes near the present glacier terminus in the upper inlet. The areal distribution of sedimentary facies within the basins is interpreted using the seismic facies architecture and inferences from known sediment characteristics proximal to present glacier termini.

  20. Stratified precambrian rocks (sedimentary?) beneath the midcontinent region of the US. Final technical report

    SciTech Connect

    Hauser, E.C.

    1993-02-01

    A thick sequence of layered rocks occurs beneath the Phanerozoic platform strata which blanket the US midcontinent. Observed on COCORP deep reflection data in southern Illinois and Indiana and in SW Oklahoma and adjacent Texas, this sequence is locally 1--3 times as thick as the overlying Paleozoic cover, but the origin of this sequence and its ultimate lateral extent are unknown. However, the occurrences of Precambrian layered rocks on both the COCORP profiles and reprocessed industry seismic reflection data from the region lie within regions of generally low amplitude and low frequency aeromagnetic anomaly, suggesting an even greater distribution. Unmetamorphosed Precambrian sedimentary rocks have been recovered from drill holes in southwest Ohio and adjacent northern Kentucky and southwesternmost Indiana. These Precambrian sedimentary rocks lie above and may be part of an underlying package of strongly layered rocks imaged on a short and shallow seismic profile in southwest Ohio. These Precambrian sedimentary rocks were originally viewed as part of a late Precambrian (Keweenawan?) rift; however, in light of Grenville foreland structures seen on the COCORP profile to the north in west central Ohio, these Precambrian strata may (1) be part of a heretofore unrecognized Grenville foreland basin, or (2) indicate that unmetamorphosed Precambrian sedimentary material may be an important constituent of the layered rocks observed on COCORP beneath southern Illinois and Indiana.

  1. Stratified precambrian rocks (sedimentary ) beneath the midcontinent region of the US

    SciTech Connect

    Hauser, E.C.

    1993-02-01

    A thick sequence of layered rocks occurs beneath the Phanerozoic platform strata which blanket the US midcontinent. Observed on COCORP deep reflection data in southern Illinois and Indiana and in SW Oklahoma and adjacent Texas, this sequence is locally 1--3 times as thick as the overlying Paleozoic cover, but the origin of this sequence and its ultimate lateral extent are unknown. However, the occurrences of Precambrian layered rocks on both the COCORP profiles and reprocessed industry seismic reflection data from the region lie within regions of generally low amplitude and low frequency aeromagnetic anomaly, suggesting an even greater distribution. Unmetamorphosed Precambrian sedimentary rocks have been recovered from drill holes in southwest Ohio and adjacent northern Kentucky and southwesternmost Indiana. These Precambrian sedimentary rocks lie above and may be part of an underlying package of strongly layered rocks imaged on a short and shallow seismic profile in southwest Ohio. These Precambrian sedimentary rocks were originally viewed as part of a late Precambrian (Keweenawan ) rift; however, in light of Grenville foreland structures seen on the COCORP profile to the north in west central Ohio, these Precambrian strata may (1) be part of a heretofore unrecognized Grenville foreland basin, or (2) indicate that unmetamorphosed Precambrian sedimentary material may be an important constituent of the layered rocks observed on COCORP beneath southern Illinois and Indiana.

  2. The potassic sedimentary rocks in Gale Crater, Mars, as seen by ChemCam Onboard Curiosity

    USGS Publications Warehouse

    Le Deit, Laetitia; Mangold, Nicolas; Forni, Olivier; Cousin, Agnes; Lasue, Jeremie; Schröder, Susanne; Wiens, Roger C.; Sumner, Dawn Y.; Fabre, Cecile; Stack, Katherine M.; Anderson, Ryan; Blaney, Diana L.; Clegg, Samuel M.; Dromart, Gilles; Fisk, Martin; Gasnault, Olivier; Grotzinger, John P.; Gupta, Sanjeev; Lanza, Nina; Le Mouélic, Stephane; Maurice, Sylvestre; McLennan, Scott M.; Meslin, Pierre-Yves; Nachon, Marion; Newsom, Horton E.; Payre, Valerie; Rapin, William; Rice, Melissa; Sautter, Violaine; Treiman, Alan H.

    2016-01-01

    The Mars Science Laboratory rover Curiosity encountered potassium-rich clastic sedimentary rocks at two sites in Gale Crater, the waypoints Cooperstown and Kimberley. These rocks include several distinct meters thick sedimentary outcrops ranging from fine sandstone to conglomerate, interpreted to record an ancient fluvial or fluvio-deltaic depositional system. From ChemCam Laser-Induced Breakdown Spectroscopy (LIBS) chemical analyses, this suite of sedimentary rocks has an overall mean K2O abundance that is more than 5 times higher than that of the average Martian crust. The combined analysis of ChemCam data with stratigraphic and geographic locations reveals that the mean K2O abundance increases upward through the stratigraphic section. Chemical analyses across each unit can be represented as mixtures of several distinct chemical components, i.e., mineral phases, including K-bearing minerals, mafic silicates, Fe-oxides, and Fe-hydroxide/oxyhydroxides. Possible K-bearing minerals include alkali feldspar (including anorthoclase and sanidine) and K-bearing phyllosilicate such as illite. Mixtures of different source rocks, including a potassium-rich rock located on the rim and walls of Gale Crater, are the likely origin of observed chemical variations within each unit. Physical sorting may have also played a role in the enrichment in K in the Kimberley formation. The occurrence of these potassic sedimentary rocks provides additional evidence for the chemical diversity of the crust exposed at Gale Crater.

  3. Detrital zircon (U-Th)/He thermochronometry in the sedimentary basin and its geological significance

    NASA Astrophysics Data System (ADS)

    Cai, C.; Qiu, N.

    2015-12-01

    The zircon (U-Th)/He thermochronometry has been used as a thermal indicator to study thermal history of the deep sedimentary basin at high temperature. The closure temperature and age of helium are important parameters for the zircon (U-Th)/He thermochronometry. In this paper, the zircon He closure temperature and its influence factors were studied by establishing the evolutionary pattern between zircon He ages and zircon burial depth based on examined zircon He ages of natural borehole samples obtained from the Cenozoic strara in the sedimentary basin. The results show that the zircon He closure temperature of natural samples in the sedimentary basin is approcimately 195℃, higher than the result (183℃) obtain from the thermal simulation experiments. The high He closure temperature resulted from long term radiation damage accumulation and high effective uranium. We also point out that grain radius, He corrected parameter, effective uranium concentration, radiation damage and radiogenic 4He concentration have apparent influence on the zircon He ages. This study is a revaluation of the conventional zircon He closure temperature. Thus, properly understanding the zircon He ages, closure temperature, and its influence factors, zircon (U-Th)/He dating can provide the true explanation of the testing zircon He ages, and has a great guiding significance in the studying of the evolution of source rocks and the process of hydrocarbon accumulation in the deep sedimentary basin.

  4. Did massive glacial dewatering modify sedimentary structures on the Amundsen Sea Embayment shelf, West Antarctica?

    NASA Astrophysics Data System (ADS)

    Weigelt, Estella; Uenzelmann-Neben, Gabriele; Gohl, Karsten; Larter, Robert D.

    2012-07-01

    Multichannel seismic reflection lines collected in the western Amundsen Sea Embayment (ASE) provide an insight into the sedimentary cover on the shelf, which documents glacial processes. Numerous columnar, reflection-poor structures penetrating the sedimentary sequences on the middle shelf form the focus of this study. The features range between 50 and 500 m in width, and from a few metres up to 500 m in height. The columns originate and end at different depths, but do not seem to penetrate to the seafloor. They show well-defined vertical boundaries, and reflection signals can be identified below them. Hence, we exclude gas-bearing chimneys. Based on the general seismic reflection characteristics we suggest that the columns originate from dewatering processes which occur close to glaciated areas where fluids are pressed out of rapidly loaded sediments. Likely several mud-diapirs rise from water-rich mud layers within a mixed sedimentary succession and penetrate overlying denser and coarse-grained sediment strata. The presence of fluid-escape veins indicates a glacial origin and overprinting of the older sedimentary sequences on the ASE. The locations of the structures indicate that grounded ice sheets reached at least onto the middle shelf during former glacial periods.

  5. Underground Research Laboratories for Crystalline Rock and Sedimentary Rock in Japan

    SciTech Connect

    Shigeta, N.; Takeda, S.; Matsui, H.; Yamasaki, S.

    2003-02-27

    The Japan Nuclear Cycle Development Institute (JNC) has started two off-site (generic) underground research laboratory (URL) projects, one for crystalline rock as a fractured media and the other for sedimentary rock as a porous media. This paper introduces an overview and current status of these projects.

  6. A New Unusual Ice-induced Sedimentary Structure: the Silt Mushroom

    PubMed Central

    Jianhua, Zhong; Liangtian, Ni; Ningliang, Sun; Chuang, Liu; Bing, Hao; Mengchun, Cao; xin, Chen; Ke, Luo; Shengxin, Liu; Leitong, Huang; Guanqun, Yang; Shaojie, Wang; Feifei, Su; Xuejing, He; Yanqiu, Xue

    2016-01-01

    Upon channel bars or point bars within the lows of the Yellow River, a new sedimentary structure, named ‘silt mushroom’, has been observed. The process of their formation is interpreted to be via the ice process. The name, the silt mushroom comes from their figurative form. This is because they look somewhat similar to mushroom’s in size and shape; being in the range of 1 to 10 cm in diameter, with the medium 3–5 cm, and on average 10 cm in height, occuring generally in groups, and occasionally in isolation in relatively soft silt. They develop in the transition from winter to spring, and are convincingly related to ice processes. Ice-induced silt mushrooms are best examined in association with the many other newly discovered ice-induced sedimentary structures (over 20 kinds). Clearly, up to now, ice processes have been significantly underestimated. With the substantial discovery of the ice-induced silt mushroom, it opens up new questions. This is because its structure mirrors the same sedimentary structures found in rocks, questioning their genesis, and sedimentary environment analysis. This achievement is significant not only in sedimentology, but also in palaeogeography, palaeoclimate, geological engineering, hydraulics and fluviology. PMID:27833155

  7. Distinctive sedimentary features of cold-climate eolian deposits, North Park, Colorado

    USGS Publications Warehouse

    Ahlbrandt, T.S.; Andrews, S.

    1978-01-01

    Cold-climate eolianites contain diagnostic sedimentary features that contrast with the sedimentary features of warm-climate eolianites. Distinctive tensional, compressional, and dissipation sedimentary structures related to freezing, thawing and snow melting characterize eolian dune-sand deposits in North Park, Colorado. The North Park dunes have few of the characteristics considered to be diagnostic eolian indicators. A significant difference is the heterogeneous texture and composition of the sand. The migration rate of these active dunes is slow (???1.7 m/year) due to freezing of moisture in the sand or to burial of the sand by snow during half of the year, even though the dunes occur in a unimodal, high-energy wind environment. Bioturbation is common in both active and inactive dunes, although the dunes occur at a high elevation ({reversed tilde} 2500m) in a cold climate (3.0??C mean annual temperature). The distinctive sedimentary features observed in this cold-climate (snow-related) dune field should aid in the interpretation of eolianites and the paleoclimates in which they formed. ?? 1978.

  8. Sedimentary rock types: relative proportions as a function of geological time.

    PubMed

    Garrels, R M; Mackenzie, F T

    1969-02-07

    Proportions of sedimentary rock types remaining today differ from period to period. These differences may be chiefly the result of differential rates of deposition and erosion of the various components of the rocks. Lower percentages of limestones and evaporites in Precambrian rocks than in post-Precambrian rocks probably represent selective loss of these more easily removable components from the original deposits.

  9. Shallow Sedimentary Structure of the Brahmaputra Valley Constraint from Receiver Functions Analysis

    NASA Astrophysics Data System (ADS)

    Saikia, Sowrav; Chopra, Sumer; Baruah, Santanu; Singh, Upendra K.

    2017-01-01

    In this study, receiver functions from ten Broadband seismograph stations on Cenozoic sediment formations of Brahmaputra valley and its neighboring region in northeastern part of India are determined. Receiver function traces from this region show delay in peak by 1-2.5 s and associated minor peaks with the direct P-phase peak. Based on such observation, we try to image sedimentary structure of the Brahmaputra valley plain, adjacent Shillong plateau and Himalayan foredeep region. An adapted hybrid global waveform inversion technique has been applied to extract sedimentary basin structure beneath each site. The sedimentary cover of the basin is about 0.5-6.5 km thick across the valley, 0.5-1.0 km on Shillong plateau and 2.0-5.0 km in nearby foredeep region. We have found that sedimentary thickness increases from SW to NE along the Brahmaputra valley and towards the Eastern Himalayan syntaxes. The estimated sediment thickness and S wave velocity structure agree well with the results of previous active source, gravity, and deep borehole studies carried out in this region. The thick crustal low velocity sediment cover in Brahmaputra valley is expected to amplify ground motions during earthquakes and therefore important for seismic hazard assessment of the region.

  10. USING THE SEDIMENT QUALITY TRIAD (SQT) APPROACH TO ASSESS SEDIMENTARY CONTAMINATION IN THE ANACOSTIA RIVER, WASHINGTON

    EPA Science Inventory

    Using the Sediment Quality Triad (SQT) Approach to Assess Sedimentary Contamination in the Anacostia River, Washington, D.C. Velinsky, DJ*1, Ashley, JTF1,2, Pinkney, F.3, McGee, BL3 and Norberg-King, TJ.4 1Academy of Natural Sciences-PCER, Philadelphia, PA. 2Philadelphia Universi...

  11. The role of springs and sedimentary volcanism in Martian Geological Record

    NASA Astrophysics Data System (ADS)

    Pio Rossi, Angelo; Pondrelli, Monica

    Mars has a rich and complex sedimentary record. It is believed to be largely Noachian, but its age is poorly constrained, mostly due to the heavy erosion and modification of the deposits. Layered Light-Toned Deposits (LTDs) are prominent among them, and they crop out in sev-eral discrete locations on Mars. The range of genetic models for these deposits is extremely wide (also including non-sedimentary mechanisms). Regardless their actual origin, there is a very good chance that these deposits have possibly recorded past climatic and environmental conditions. We concentrated our analysis in Arabia Terra, where several craters are hosting thick (up to few km) stacks of layered sedimentary-looking rocks, such as Becquerel and Crom-melin. Although clear indications of allogenic signals are present in the sedimentary record, there are evidences for both depositional and structural features suggestive of internal dynamic control. These include: evidence of local sources, structural control on LTDs occurrence and development, synsedimentary deformation and (soft?) sediment expulsion. We interpret, at least partially LTDs in Arabia Terra as the result of groundwater emergence and spring-based deposition, which likely occurred along with other processes, such as climatically controlled variable eolian input. Therefore Martian LTDs might retain a precious record of both allogenic and autogenic effects.

  12. Resolving the Sedimentary Basin Structure from Oklahoma with Local Receiver Function

    NASA Astrophysics Data System (ADS)

    Zheng, D.; Ni, S.

    2015-12-01

    The teleseismic receiver function is defined as the radial component of P wave being deconvoluted from the vertical component of the earthquakes with magnitude larger than 5.5 at teleseismic distances. It has successfully been applied in resolving the structure of the crust and upper mantle in many regions. The receiver function can also be used to determine the thickness of sedimentary basin. However the corner frequency of the P waves from the teleseismic events (M>5.5) is relatively low and the high frequency content in the teleseismic P waves is attenuated, thus, the teleseismic receiver function is usually not sufficient to reveal details of sedimentary basin structure. Instead, local small earthquake (~ M3) generates P waves of short duration waveforms with high frequency content, which can be used to calculate receiver functions (called local receiver function). As a case study, we study waveform data from local earthquakes in Oklahoma. We first explore feasibility of local receiver function for different magnitude, focal depth, epicentral distance, filtering band and time window length. After local receiver functions are computed, we search the best velocity model to fit the local receiver function waveforms with the Differential Evolution (DE) algorithm which is a global optimization method. We invert the sedimentary basin structure in Oklahoma and find that this method is suitable for other area for the sedimentary basin structure where local seismic waveforms are available.

  13. Thermal history determined by fission-track dating for three sedimentary basins in California and Wyoming

    USGS Publications Warehouse

    Naeser, Nancy D.

    1984-01-01

    The use of fission-tracks is demonstrated in studies of time-temperature relationships in three sedimentary basins in the western United States; in the Tejon Oil Field area of the southern San Joaquin Valley, California; in the northeastern Green River basin, Wyoming, and in drill holes in the southern Powder River Basin, Wyoming.

  14. Phanerozoic growth of the epicontinental sedimentary reservoir: implications for long-term sea level change

    NASA Astrophysics Data System (ADS)

    Husson, J. M.; Peters, S. E.

    2015-12-01

    Earth's sedimentary carapace contains the largest surface-accessible reservoir of biogeochemically sensitive elements and contains several times more water than all of the present-day ice caps and glaciers combined. It is, therefore, widely recognized that on timescales of ~1 Myr, one of the most important factors governing the evolution of many Earth systems is the exchange of materials into and out of the sedimentary shell. Although it is rarely assumed that these rates of exchange are invariant, it is generally presumed that the sedimentary reservoir as a whole behaves as a single large, slowly cycling system in which erosion and sediment storage are balanced; hence the expectation that there is no net change in sediment volume. Here, using the Macrostrat database, which consists of surface and subsurface data for 1,474 locations as well as more than 700K geologic map-based polygons, we show that the sedimentary reservoir is best conceived of as multiple reservoirs with different intrinsic cycling rates determined by tectonic and environmental contexts of deposition. We also show that the volume of sediment stored on presently subaerially exposed North America has increased markedly during the Phanerozoic. Initiation of growth in the size of this epicontinental sedimentary reservoir is well recorded by the Great Unconformity, which separates predominately Precambrian-aged, low porosity crystalline and metamorphic basement rocks from overlying, more porous Cambrian and younger sedimentary deposits. Geologic map-based data from Eurasia and Australia suggest similar overall patterns globally. Thus, after burial of the subaerially exposed Great Unconformity surface by Cambrian-Ordovician sediments, the groundwater storage capacity of the continents increased by more than 15 million cubic km (~1% of present ocean volume). Subsequent burial by younger sedimentary deposits further increased epicontinental groundwater storage capacity to the ~130 million cubic km it

  15. 1.8 Billion Years of Detrital Zircon Recycling Calibrates a Refractory Part of Earth’s Sedimentary Cycle

    PubMed Central

    Hadlari, Thomas; Swindles, Graeme T.; Galloway, Jennifer M.; Bell, Kimberley M.; Sulphur, Kyle C.; Heaman, Larry M.; Beranek, Luke P.; Fallas, Karen M.

    2015-01-01

    Detrital zircon studies are providing new insights on the evolution of sedimentary basins but the role of sedimentary recycling remains largely undefined. In a broad region of northwestern North America, this contribution traces the pathway of detrital zircon sand grains from Proterozoic sandstones through Phanerozoic strata and argues for multi-stage sedimentary recycling over more than a billion years. As a test of our hypothesis, integrated palynology and detrital zircon provenance provides clear evidence for erosion of Carboniferous strata in the northern Cordillera as a sediment source for Upper Cretaceous strata. Our results help to calibrate Earth's sedimentary cycle by showing that recycling dominates sedimentary provenance for the refractory mineral zircon. PMID:26658165

  16. Modes of sedimentary basin formation in the north-eastern Black Sea

    NASA Astrophysics Data System (ADS)

    Stephenson, Randell; Starostenko, Vitaly; Sydorenko, Grygoriy; Yegorova, Tamara

    2016-04-01

    The Greater Caucasus and Black Sea sedimentary basins developed in a Mesozoic back-arc setting, the former older than the latter (Jurassic v. Cretaceous). Compressional shortening of the former and accompanying ongoing development of marginal basin depocentres in the north-eastern Black Sea - which is closely tied to the formation of the Crimea-Greater Caucasus orogen - is a Cenozoic phenomenon, starting in the Eocene and proceeding until the present day. Recently, the sedimentary basin/crust/lithosphere geometry of the study area has been characterised across a range of scales using regional seismic reflection profiling, long-offset refraction/wide-angle reflection profiling and local earthquake tomography. These provide a new integrated image of the present-day crustal structure and sedimentary basin architecture of the northern margin of the eastern Black Sea, north across the Azov Sea and provide evidence of the deeper expression of sedimentary basins and the processes controlling the geometry of their inversion during the Cenozoic. It is inferred that the Greater Caucasus paleo-Basin, lying stratigraphically below the Black Sea and younger sedimentary successions, extends further to the west than previously known. This basin has significant thickness in the area between the Azov and Black seas and probably forms the deeper core of the Crimea-Caucasus inversion zone. The Crimea-Greater Caucasus orogenic belt is the expression of "basin inversion" of the Jurassic Greater Caucasus paleo-Basin, the degree of inversion of which varies along strike. The Greater Caucasus foredeep basins - Indolo-Kuban and Sorokin-Tuapse troughs -represent syn-inversional marginal troughs to the main inversion zone. The Shatsky Ridge - the northern flank of the main East Black Sea Basin - may also be mainly a syn-inversional structure, underlain by a blind thrust zone expressed as a northward dipping zone of seismicity on the northern margin of the eastern Black Sea.

  17. Geoarchaeological investigations of a Mesolithic-Neolithic Sedimentary Sequence from Queens Sedgemoor, Somerset, UK

    NASA Astrophysics Data System (ADS)

    Hill, Tom; Whittaker, John; Brunning, Richard; Law, Matthew; Bell, Martin; Wilkinson, Keith

    2016-04-01

    A geoarchaeological investigation was undertaken at Queens Sedgemoor in Somerset, southwest England, as part of the English Heritage funded project 'the Mesolithic wetland/dryland edge in Somerset' (EH 6624). This project was designed to address the National Heritage Protection Plan (Topic 4G) associated with the assessment of the character and significance of sedimentary and wetland archaeology. As part of the project, a sediment core extracted from the site and has undergone high resolution radiocarbon dating, with subsequent detailed and directed micropalaeontological analyses (pollen, diatom, foraminifera, ostracoda, mollusca) focussing on the sedimentary sequence associated with the Mesolithic and early Neolithic periods. The presentation summarises the results of this multiproxy analyses and explains how it has assisted in understanding the landscape during a period of substantial prehistoric importance in southwest England. The sedimentary sequence dates back to the Mesolithic period (7.6ky BP) and the microfossil evidence indicates hydroseral succession has taken place, with the initial establishment of a freshwater lake, prior to undergoing terrestrialisation and the eventual development of a raised bog. Holocene sea-level change also influenced the sedimentary archive. Due to a rise in relative sea level c. 6.7ky BP, subsequent coastal inundation and estuarine sedimentation took also place and is hereby associated with the Lower Wentlooge Formation of the Somerset Levels. Although poor pollen preservation was encountered within the section specifically associated with the Mesolithic-Neolithic transition, a clear picture of landscape change is presented for the sedimentary archive, with evidence indicative of landscape modification by humans since the late Mesolithic.

  18. Methane flux and stable hydrogen and carbon isotope composition of sedimentary methane from the Florida Everglades

    NASA Astrophysics Data System (ADS)

    Burke, Roger A., Jr.; Barber, Timothy R.; Sackett, William M.

    1988-12-01

    Methane flux and the stable isotopic composition of sedimentary methane were measured at four locations in the Florida Everglades system. Individual estimates of methane flux ranged over more than 3 orders of magnitude, from about 0.001 to 2.6 g CH4 m-2 d-1. Significant interstation differences in total methane flux were also observed and are judged most likely attributable to differences in the size and spacing of emergent aquatic vegetation, and possibly differences in the type (i.e., vascular plant versus algal) of organic matter incorporated into the sediments. On the basis of measurements presented here and by other investigators, the Everglades system appears to be a relatively weak source of atmospheric methane, probably contributing less than 0.5 Tg CH4 yr-1. Emergent aquatic plants appear to be capable of indirectly affecting the stable isotopic composition of sedimentary methane by stimulating methane oxidation via root aeration. A significant positive correlation between δD-CH4 and δ13C-CH4 was observed for samples collected from sediments covered by tall, dense stands of emergent plants. In contrast, a significant negative correlation between the δD and δ13C of sedimentary methane was observed for samples collected at an open water site where ebullition dominated methane transfer to the atmosphere. The mean δ13C of sedimentary methane samples measured in the Everglades system (mean δ13C =-61.7‰, s.d. = 3.6‰, n = 51) is not significantly different from the estimated average δ13C of all natural sources (-58.3‰). The mean δD of Everglades sedimentary methane (mean δ D = -293‰, s.d. = 14‰, n = 50) appears to be slightly less D-depleted than the estimated average methane (δD =-360 ± 30‰) from all sources.

  19. Aeolian sedimentary processes at the Bagnold Dunes, Mars: Implications for modern dune dynamics and sedimentary structures in the aeolian stratigraphic record of Mars

    NASA Astrophysics Data System (ADS)

    Ewing, Ryan C.; Bridges, Nathan T.; Sullivan, Rob; Lapotre, Mathieu G. A.; Fischer, Woodward W.; Lamb, Mike P.; Rubin, David M.; Lewis, Kevin W.; Gupta, Sanjeev

    2016-04-01

    Wind-blown sand dunes are ubiquitous on the surface of Mars and are a recognized component of the martian stratigraphic record. Our current knowledge of the aeolian sedimentary processes that determine dune morphology, drive dune dynamics, and create aeolian cross-stratification are based upon orbital studies of ripple and dune morphodynamics, rover observations of stratification on Mars, Earth analogs, and experimental and theoretical studies of sand movement under Martian conditions. In-situ observations of sand dunes (informally called the Bagnold Dunes) by Curiosity Rover in Gale Crater, Mars provide the first opportunity to make observations of dunes from the grain-to-dune scale thereby filling the gap in knowledge between theory and orbital observations and refining our understanding of the martian aeolian stratigraphic record. We use the suite of cameras on Curiosity, including Navigation Camera (Navcam), Mast Camera (Mastcam) and Mars Hand Lens Imager (MAHLI), to make observations of the Bagnold Dunes. Measurements of sedimentary structures are made where stereo images are available. Observations indicate that structures generated by gravity-driven processes on the dune lee slopes, such as grainflow and grainfall, are similar to the suite of aeolian sedimentary structures observed on Earth and should be present and recognizable in Mars' aeolian stratigraphic record. Structures formed by traction-driven processes deviate significantly from those found on Earth. The dune hosts centimeter-scale wind ripples and large, meter-scale ripples, which are not found on Earth. The large ripples migrate across the depositional, lee slopes of the dune, which implies that these structures should be present in Mars' stratigraphic record and may appear similar to compound-dune stratification.The Mars Science Laboratory Curiosity Rover Team is acknowledged for their support of this work.

  20. Industrial application experiment series

    NASA Technical Reports Server (NTRS)

    Bluhm, S. A.

    1981-01-01

    Two procurements within the Industrial Application Experiment Series of the Thermal Power Systems Project are discussed. The first procurement, initiated in April 1980, resulted in an award to the Applied Concepts Corporation for the Capital Concrete Experiment: two Fresnel concentrating collectors will be evaluated in single-unit installations at the Jet Propulsion Laboratory Parabolic Dish Test Site and at Capitol Concrete Products, Topeka, Kansas. The second procurement, initiated in March 1981, is titled, "Thermal System Engineering Experiment B." The objective of the procurement is the rapid deployment of developed parabolic dish collectors.

  1. Geoengineering Research for a Deep Underground Science and Engineering Laboratory in Sedimentary Rock

    NASA Astrophysics Data System (ADS)

    Mauldon, M.

    2004-12-01

    A process to identify world-class research for a Deep Underground Science and Engineering Laboratory (DUSEL) in the USA has been initiated by NSF. While allowing physicists to study, inter alia, dark matter and dark energy, this laboratory will create unprecedented opportunities for biologists to study deep life, geoscientists to study crustal processes and geoengineers to study the behavior of rock, fluids and underground cavities at depth, on time scales of decades. A substantial portion of the nation's future infrastructure is likely to be sited underground because of energy costs, urban crowding and vulnerability of critical surface facilities. Economic and safe development of subsurface space will require an improved ability to engineer the geologic environment. Because of the prevalence of sedimentary rock in the upper continental crust, much of this subterranean infrastructure will be hosted in sedimentary rock. Sedimentary rocks are fundamentally anisotropic due to lithology and bedding, and to discontinuities ranging from microcracks to faults. Fractures, faults and bedding planes create structural defects and hydraulic pathways over a wide range of scales. Through experimentation, observation and monitoring in a sedimentary rock DUSEL, in conjunction with high performance computational models and visualization tools, we will explore the mechanical and hydraulic characteristics of layered rock. DUSEL will permit long-term experiments on 100 m blocks of rock in situ, accessed via peripheral tunnels. Rock volumes will be loaded to failure and monitored for post-peak behavior. The response of large rock bodies to stress relief-driven, time-dependent strain will be monitored over decades. Large block experiments will be aimed at measurement of fluid flow and particle/colloid transport, in situ mining (incl. mining with microbes), remediation technologies, fracture enhancement for resource extraction and large scale long-term rock mass response to induced

  2. Uranium series, volcanic rocks

    USGS Publications Warehouse

    Vazquez, Jorge A.

    2014-01-01

    Application of U-series dating to volcanic rocks provides unique and valuable information about the absolute timing of crystallization and differentiation of magmas prior to eruption. The 238U–230Th and 230Th-226Ra methods are the most commonly employed for dating the crystallization of mafic to silicic magmas that erupt at volcanoes. Dates derived from the U–Th and Ra–Th methods reflect crystallization because diffusion of these elements at magmatic temperatures is sluggish (Cherniak 2010) and diffusive re-equilibration is insignificant over the timescales (less than or equal to 10^5 years) typically associated with pre-eruptive storage of nearly all magma compositions (Cooper and Reid 2008). Other dating methods based on elements that diffuse rapidly at magmatic temperatures, such as the 40Ar/39Ar and (U–Th)/He methods, yield dates for the cooling of magma at the time of eruption. Disequilibrium of some short-lived daughters of the uranium series such as 210Po may be fractionated by saturation of a volatile phase and can be employed to date magmatic gas loss that is synchronous with volcanic eruption (e.g., Rubin et al. 1994).

  3. Series Bosch System Development

    NASA Technical Reports Server (NTRS)

    Abney, Morgan B.; Evans, Christopher; Mansell, Matt; Swickrath, Michael

    2012-01-01

    State-of-the-art (SOA) carbon dioxide (CO2) reduction technology for the International Space Station produces methane as a byproduct. This methane is subsequently vented overboard. The associated loss of hydrogen ultimately reduces the mass of oxygen that can be recovered from CO2 in a closed-loop life support system. As an alternative to SOA CO2 reduction technology, NASA is exploring a Series-Bosch system capable of reducing CO2 with hydrogen to form water and solid carbon. This results in 100% theoretical recovery of oxygen from metabolic CO2. In the past, Bosch-based technology did not trade favorably against SOA technology due to a high power demand, low reaction efficiencies, concerns with carbon containment, and large resupply requirements necessary to replace expended catalyst cartridges. An alternative approach to Bosch technology, labeled "Series-Bosch," employs a new system design with optimized multi-stage reactors and a membrane-based separation and recycle capability. Multi-physics modeling of the first stage reactor, along with chemical process modeling of the integrated system, has resulted in a design with potential to trade significantly better than previous Bosch technology. The modeling process and resulting system architecture selection are discussed.

  4. Chemistry of decomposition of freshwater wetland sedimentary organic material during ramped pyrolysis

    NASA Astrophysics Data System (ADS)

    Williams, E. K.; Rosenheim, B. E.

    2011-12-01

    Ramped pyrolysis methodology, such as that used in the programmed-temperature pyrolysis/combustion system (PTP/CS), improves radiocarbon analysis of geologic materials devoid of authigenic carbonate compounds and with low concentrations of extractable authochthonous organic molecules. The approach has improved sediment chronology in organic-rich sediments proximal to Antarctic ice shelves (Rosenheim et al., 2008) and constrained the carbon sequestration potential of suspended sediments in the lower Mississippi River (Roe et al., in review). Although ramped pyrolysis allows for separation of sedimentary organic material based upon relative reactivity, chemical information (i.e. chemical composition of pyrolysis products) is lost during the in-line combustion of pyrolysis products. A first order approximation of ramped pyrolysis/combustion system CO2 evolution, employing a simple Gaussian decomposition routine, has been useful (Rosenheim et al., 2008), but improvements may be possible. First, without prior compound-specific extractions, the molecular composition of sedimentary organic matter is unknown and/or unidentifiable. Second, even if determined as constituents of sedimentary organic material, many organic compounds have unknown or variable decomposition temperatures. Third, mixtures of organic compounds may result in significant chemistry within the pyrolysis reactor, prior to introduction of oxygen along the flow path. Gaussian decomposition of the reaction rate may be too simple to fully explain the combination of these factors. To relate both the radiocarbon age over different temperature intervals and the pyrolysis reaction thermograph (temperature (°C) vs. CO2 evolved (μmol)) obtained from PTP/CS to chemical composition of sedimentary organic material, we present a modeling framework developed based upon the ramped pyrolysis decomposition of simple mixtures of organic compounds (i.e. cellulose, lignin, plant fatty acids, etc.) often found in sedimentary

  5. Classification scheme for sedimentary and igneous rocks in Gale crater, Mars

    NASA Astrophysics Data System (ADS)

    Mangold, N.; Schmidt, M. E.; Fisk, M. R.; Forni, O.; McLennan, S. M.; Ming, D. W.; Sautter, V.; Sumner, D.; Williams, A. J.; Clegg, S. M.; Cousin, A.; Gasnault, O.; Gellert, R.; Grotzinger, J. P.; Wiens, R. C.

    2017-03-01

    Rocks analyzed by the Curiosity rover in Gale crater include a variety of clastic sedimentary rocks and igneous float rocks transported by fluvial and impact processes. To facilitate the discussion of the range of lithologies, we present in this article a petrological classification framework adapting terrestrial classification schemes to Mars compositions (such as Fe abundances typically higher than for comparable lithologies on Earth), to specific Curiosity observations (such as common alkali-rich rocks), and to the capabilities of the rover instruments. Mineralogy was acquired only locally for a few drilled rocks, and so it does not suffice as a systematic classification tool, in contrast to classical terrestrial rock classification. The core of this classification involves (1) the characterization of rock texture as sedimentary, igneous or undefined according to grain/crystal sizes and shapes using imaging from the ChemCam Remote Micro-Imager (RMI), Mars Hand Lens Imager (MAHLI) and Mastcam instruments, and (2) the assignment of geochemical modifiers based on the abundances of Fe, Si, alkali, and S determined by the Alpha Particle X-ray Spectrometer (APXS) and ChemCam instruments. The aims are to help understand Gale crater geology by highlighting the various categories of rocks analyzed by the rover. Several implications are proposed from the cross-comparisons of rocks of various texture and composition, for instance between in place outcrops and float rocks. All outcrops analyzed by the rover are sedimentary; no igneous outcrops have been observed. However, some igneous rocks are clasts in conglomerates, suggesting that part of them are derived from the crater rim. The compositions of in-place sedimentary rocks contrast significantly with the compositions of igneous float rocks. While some of the differences between sedimentary rocks and igneous floats may be related to physical sorting and diagenesis of the sediments, some of the sedimentary rocks (e

  6. Series with Inverse Function Terms

    ERIC Educational Resources Information Center

    Ovchinnikov, Sergei

    2011-01-01

    Finding the sum of a series in the form of a closed expression has always been a challenging problem in analysis. The paper presents an elementary method for summation of series with terms generated by functions satisfying subtraction identities.

  7. GPS Position Time Series @ JPL

    NASA Technical Reports Server (NTRS)

    Owen, Susan; Moore, Angelyn; Kedar, Sharon; Liu, Zhen; Webb, Frank; Heflin, Mike; Desai, Shailen

    2013-01-01

    Different flavors of GPS time series analysis at JPL - Use same GPS Precise Point Positioning Analysis raw time series - Variations in time series analysis/post-processing driven by different users. center dot JPL Global Time Series/Velocities - researchers studying reference frame, combining with VLBI/SLR/DORIS center dot JPL/SOPAC Combined Time Series/Velocities - crustal deformation for tectonic, volcanic, ground water studies center dot ARIA Time Series/Coseismic Data Products - Hazard monitoring and response focused center dot ARIA data system designed to integrate GPS and InSAR - GPS tropospheric delay used for correcting InSAR - Caltech's GIANT time series analysis uses GPS to correct orbital errors in InSAR - Zhen Liu's talking tomorrow on InSAR Time Series analysis

  8. Series of Reciprocal Triangular Numbers

    ERIC Educational Resources Information Center

    Bruckman, Paul; Dence, Joseph B.; Dence, Thomas P.; Young, Justin

    2013-01-01

    Reciprocal triangular numbers have appeared in series since the very first infinite series were summed. Here we attack a number of subseries of the reciprocal triangular numbers by methodically expressing them as integrals.

  9. Short and long term sediment flux in an inner-alpine sedimentary basin (Hohe Tauern, Austria)

    NASA Astrophysics Data System (ADS)

    Götz, Joachim; Schrott, Lothar

    2015-04-01

    Combined analyses of short and long term sediment fluxes in mountain environments have been rarely carried out until now. However, the relation of integrated postglacial landform volumes to single events (e.g. debris flows) provide the opportunity to establish meaningful frequency-magnitude-relationships, to evaluate present day geomorphic activity more reasonable, and to complement time series data typically covering only a short period of time. In this study we investigate recent and postglacial sediment flux in a small-scale denudation-accumulation system in the Hohe Tauern Range (Austrian Alps) using a complementary multi method approach including surface, subsurface and temporal analyses. We reconstructed the infill history and sedimentary architecture of the almost closed Gradenmoos basin, which has been filled up with sediments from different source areas delivered by mainly debris flows, rockfall and avalanche activity, and fluvial processes. In former times, glacial, glacio-fluvial and lacustrine sedimentation contributed to the basin fill as well. This process diversity led to a variety of interfingering and nested sediment storage landforms with a complex postglacial stratigraphy. Most important landforms include floodplain and peat bog deposits in the basin center as well as debris cones and talus sheets adjacent to the surrounding rockwalls. Postglacial basin sedimentation started after Younger Dryas deglaciation as indicated by radiocarbon ages of early-Holocene sediment core samples taken in the basin. For the following 7500 years, trap efficiency was maximised due to the presence of a former lake which is proved by morphometric, palynologic and stratigraphic data. Peat bog development finally began around 3500 years ago in the distal part of the basin. We interpolated the bedrock interface below the basin fill deposits using bedrock coordinates derived from core-drilling, geophysical prospection (electrical resistivity tomography, refraction seismic

  10. Harmonic Series Meets Fibonacci Sequence

    ERIC Educational Resources Information Center

    Chen, Hongwei; Kennedy, Chris

    2012-01-01

    The terms of a conditionally convergent series may be rearranged to converge to any prescribed real value. What if the harmonic series is grouped into Fibonacci length blocks? Or the harmonic series is arranged in alternating Fibonacci length blocks? Or rearranged and alternated into separate blocks of even and odd terms of Fibonacci length?

  11. SERI Biomass Program

    NASA Astrophysics Data System (ADS)

    Bergeron, P. W.; Corder, R. E.; Hill, A. M.; Lindsey, H.; Lowenstein, M. Z.

    1983-02-01

    The biomass with which this report is concerned includes aquatic plants, which can be converted into liquid fuels and chemicals; organic wastes (crop residues as well as animal and municipal wastes), from which biogas can be produced via anerobic digestion; and organic or inorganic waste streams, from which hydrogen can be produced by photobiological processes. The Biomass Program Office supports research in three areas which, although distinct, all use living organisms to create the desired products. The Aquatic Species Program (ASP) supports research on organisms that are themselves processed into the final products, while the Anaerobic Digestion (ADP) and Photo/Biological Hydrogen Program (P/BHP) deals with organisms that transform waste streams into energy products. The P/BHP is also investigating systems using water as a feedstock and cell-free systems which do not utilize living organisms. This report summarizes the progress and research accomplishments of the SERI Biomass Program during FY 1982.

  12. Molecular nitrogen in natural gas accumulations: Generation from sedimentary organic matter at high temperatures

    SciTech Connect

    Littke, R.; Krooss, B.; Frielingsdorf, J.; Idiz, E.

    1995-03-01

    The occurrence of natural gas accumulations with high percentages (up to 100%) of molecular nitrogen in various hydrocarbon provinces represents a largely unresolved problem and a serious exploration risk. In this context, a geochemical and basin modeling study was performed to evaluate the potential of sedimentary organic matter to generate molecular nitrogen. The masses of nitrogen present in coals - if converted into molecular nitrogen - are sufficient to fill commercial gas reservoirs. A calculation for gas accumulations in northern Germany, where percentages of molecular nitrogen range from less than 5 to greater than 90%, reveals that the molecular nitrogen generated in underlying coal-bearing strata is sufficient to account for the nitrogen gas even in the largest fields. In addition, much of the total nitrogen in clay-rich rock types, such as shales and mudstones, is fixed in sedimentary organic matter and may add to the nitrogen generation capacity of the coals.

  13. Quantitative bounds on morphodynamics and implications for reading the sedimentary record.

    PubMed

    Ganti, Vamsi; Lamb, Michael P; McElroy, Brandon

    2014-02-28

    Sedimentary rocks are the archives of environmental conditions and ancient planetary surface processes that led to their formation. Reconstructions of Earth's past surface behaviour from the physical sedimentary record remain controversial, however, in part because we lack a quantitative framework to deconvolve internal dynamics of sediment-transport systems from environmental signal preservation. Internal dynamics of landscapes--a consequence of the coupling between bed topography, sediment transport and flow dynamics (morphodynamics)--result in regular and quasiperiodic landforms that abound on the Earth and other planets. Here, using theory and a data compilation of morphodynamic landforms that span a wide range of terrestrial, marine and planetary depositional systems, we show that the advection length for settling sediment sets bounds on the scales over which internal landscape dynamics operate. These bounds provide a universal palaeohydraulic reconstruction tool on planetary surfaces and allow for quantitative identification of depositional systems that may preserve tectonic, climatic and anthropogenic signals.

  14. Evidence for only minor contributions from bacteria to sedimentary organic carbon

    NASA Technical Reports Server (NTRS)

    Hartgers, W. A.; Sinninghe Damste, J. S.; Requejo, A. G.; Allan, J.; Hayes, J. M.; de Leeuw, J. W.

    1994-01-01

    Because their molecular signatures are often prominent in extracts of sediments, bacteria are thought to be important contributors to petroleum source beds. It has been shown recently, however, that abundances of biomarkers do not always reflect relative contributions to sedimentary organic carbon (Corg). The contribution of photosynthetic green sulphur bacteria to sediments can be assessed effectively because the diagenetic products of distinctive carotenoids from these organisms occur widely and their biomass is isotopically labelled, being enriched in 13C. We show here that, although sediments and oils from the Western Canada and Williston basins contain prominent biomarkers of photosynthetic bacteria, the absence of 13C enrichment in the total Corg requires that the bacterial contribution is in fact minimal. Although the importance of bacterial reworking of sedimentary debris cannot be doubted, we argue that our findings, when considered in conjunction with those from other settings, suggest that bacterial biomass may commonly represent only a minor component of total Corg in carbonaceous rocks.

  15. Geologic Criteria for the Assessment of Sedimentary Exhalative (Sedex) Zn-Pb-Ag Deposits

    USGS Publications Warehouse

    Emsbo, Poul

    2009-01-01

    Sedex deposits account for more than 50 percent of the world's zinc and lead reserves and furnish more than 25 percent of the world's production of these two metals. This report draws on previous syntheses as well as on topical studies of deposits in sedex basins to determine the characteristics and processes that produced sedex deposits. This analysis also uses studies of the tectonic, sedimentary, and fluid evolution of modern and ancient sedimentary basins and mass balance constraints to identify the hydrothermal processes that are required to produce sedex deposits. This report demonstrates how a genetic model can be translated into geologic criteria that can be used in the U.S. Geological Survey National Assessments for sedex zinc-lead-silver deposits to define permissive tracts, assess the relative prospectivity of permissive tracts, and map favorability within permissive tracts.

  16. Late Holocene sedimentary environments of south San Francisco Bay, California, illustrated in gravity cores

    USGS Publications Warehouse

    Woodrow, Donald L.; Fregoso, Theresa A.; Wong, Florence L.; Jaffe, Bruce E.

    2014-01-01

    Data are reported here from 51 gravity cores collected from the southern part of San Francisco Bay by the U.S. Geological Survey in 1990. The sedimentary record in the cores demonstrates a stable geographic distribution of facies and spans a few thousand years. Carbon-14 dating of the sediments suggests that sedimentation rates average about 1 mm/yr. The geometry of the bay floor and the character of the sediment deposited have remained about the same in the time spanned by the cores. However, the sedimentary record over periods of centuries or decades is likely to be much more variable. Sediments containing a few bivalve shells and bivalve or oyster coquinas are most often found west of the main channel and near the San Mateo Bridge. Elsewhere in the south bay, shells are rare except in the southernmost reaches where scattered gastropod shells are found.

  17. Estimation of Sedimentary Thickness in Kachchh Basin, Gujarat Using SP Converted Phase

    NASA Astrophysics Data System (ADS)

    Chopra, Sumer; Rao, K. M.; Rastogi, B. K.

    2010-10-01

    An inexpensive method using natural earthquake data is utilized for determining the sedimentary thickness in Kachchh. The Institute of Seismological Research (ISR) is operating a network of broadband seismographs and strong motion accelerographs in Gujarat. We used data from 13 broadband seismographs and two strong motion accelerographs in the study. The stations are within 5 to 80 km from the epicenters. In this study the S-to-P converted phase, SP, is used. This phase is generated due to large impedance contrast between sediments and basement. This phase is clear in the vertical component. The difference in the travel times of S and SP phases and velocities of P and S waves is used for determining the sedimentary layer thickness. The thickness of sediments beneath each of these 15 stations was determined covering an area of 23,500 sq km.

  18. Tectono-sedimentary processes at hyper-extended rifted margins: the Alpine and Pyrenean analogues

    NASA Astrophysics Data System (ADS)

    Masini, E.; Manatschal, G.; Mohn, G.; Tugend, J.

    2012-04-01

    The discovery of hyper-extended crust at deep-water rifted margins challenged the way of interpreting rifting and continental breakup. Indeed, syn-rift sedimentary basins, also referred to as either "supra-detachment basins" or "hyper-extended sag basins" are observed over thin hyper-extended crust that tapers oceanwards and is laterally replaced by exhumed subcontinental mantle. Studies performed off- and on-shore have shown that hyper-extended domains are formed by a complex interplay of exhumation faults leading to characteristic basin architectures. Despite of numerous interpretations of seismic sections across passive margins, the stratigraphic architecture of hyper-extended rift domains and their tectono-sedimentary evolution remain little understood. In this presentation, we present field-data from two well-preserved fossil hyper-extended domains exposed in the Alps and Pyrenees analogues that show some insights into the tectono-sedimentary evolution of hyper-extended rifted margins. Despite these two examples show a different sedimentary evolution, they exemplify how detachment systems can control accommodation space and sedimentary architecture. In both cases, the syn-rift sedimentary record can be studied in 3D allowing to evolutionary steps of supra-detachment basins to be identified. The study of these two field examples enables to identify key architectural elements of supra-detachment basins. These are detachment breakaway block and extensional allochthons, both controlling the first-order architecture of the basins. The former is the consequence of two successive low-angle detachment faults separated by a delaminated upper crustal block, whereas the latter results from the delamination of hanging-wall blocks and its emplacement over exhumed footwall. Exhumation along active detachment systems implies a very efficient creation of new real estate seafloor and results in a very specific stratigraphic record that includes from base to top: 1) a syn

  19. Analysis and Discrimination of Sedimentary, Metamorphic, and Igneous Rocks Using Laser-Induced Breakdown Spectroscopy

    NASA Astrophysics Data System (ADS)

    Rai, Ab. Kr.; Maurya, G. S.; Kumar, R.; Pathak, A. K.; Pati, J. K.; Rai, Aw. K.

    2017-01-01

    This study deals with the analysis of rocks using laser-induced breakdown spectroscopy (LIBS) coupled with principal component analysis. The spectra of sedimentary, metamorphic, and igneous rock samples were recorded in the 200-900 nm spectral range. The atomic lines of elements such as Si, Ca, Mg, Fe, Na, and K along with lighter elements, namely C, H, N, and O, were observed in these spectra. Multivariate analysis in combination with LIBS was used to classify the samples. For principal component analysis, a 12 × 5849 data matrix was formed using the results of LIBS. The plot of the analysis revealed similarities between the sedimentary and metamorphic rock samples compared with the igneous rock sample. Thus, the present study demonstrates that LIBS coupled with principal component analysis can become an important tool for rapid classification and in-situ discrimination of rock samples.

  20. Isotopic evidence of magmatism and a sedimentary carbon source at the Endeavour hydrothermal system

    SciTech Connect

    Brown, T A; Proskurowski, G; Lilley, M D

    2004-01-07

    Stable and radiocarbon isotope measurements made on CO{sub 2} from high temperature hydrothermal vents on the Endeavour Segment of the Juan de Fuca Ridge indicate both magmatic and sedimentary sources of carbon to the hydrothermal system. The Endeavour segment is devoid of overlying sediments and has shown no observable signs of surficial magmatic activity during the {approx}20 years of ongoing studies. The appearance of isotopically heavy, radiocarbon dead CO{sub 2} after a 1999 earthquake swarm requires that this earthquake event was magmatic in origin. Evidence for a sedimentary organic carbon source suggests the presence of buried sediments at the ridge axis. These findings, which represent the first temporally coherent set of radiocarbon measurements from hydrothermal vent fluids, demonstrate the utility of radiocarbon analysis in hydrothermal studies. The existence of a sediment source at Endeavour and the occurrence of magmatic episodes illustrate the extremely complex and evolving nature of the Endeavour hydrothermal system.

  1. Multi-frequency ground-penetrating radar method for revealing complex sedimentary facies

    USGS Publications Warehouse

    Delaney, A.J.; Horsman, J.; Prentice, M.L.; Arcone, S.A.

    2007-01-01

    We attempted to resolve deltaic facies in Taylor Valley, Antarctica by using pulses centered near 120, 300 and 880 MHz, the latter of which has not yet been tried in this setting, The 120 MHz profiles clearly defined gross material changes, while the 300 MHz profiles added significant resolution to the top set, foreset and bottomset beds. The additional, higher frequency provided only about 2.5 m penetration however, the 10-15 cm pulse length revealed and defined multiple, fine-scale features that were not observed with the lower frequencies. The dip of these features is, in some instances, opposite to that of larger features profiled with the lower frequencies. Profiling with 880 MHz not only confirmed the greater complexity of the sedimentary architecture, but also allowed more robust interpretation of depositional processes. Generally, we recommend pulses centered near 300-400 MHz for detailed sedimentary profiling to about 6m depth. ?? 2007 IEEE.

  2. The tectonic development and erosion of the Knox Subglacial Sedimentary Basin, East Antarctica

    NASA Astrophysics Data System (ADS)

    Maritati, A.; Aitken, A. R. A.; Young, D. A.; Roberts, J. L.; Blankenship, D. D.; Siegert, M. J.

    2016-10-01

    Sedimentary basins beneath the East Antarctic Ice Sheet (EAIS) have immense potential to inform models of the tectonic evolution of East Antarctica and its ice-sheet. However, even basic characteristics such as thickness and extent are often unknown. Using airborne geophysical data, we resolve the tectonic architecture of the Knox Subglacial Sedimentary Basin in western Wilkes Land. In addition, we apply an erosion restoration model to reconstruct the original basin geometry for which we resolve geometry typical of a transtensional pull-apart basin. The tectonic architecture strongly indicates formation as a consequence of the rifting of India from East Gondwana from ca. 160-130 Ma, and we suggest a spatial link with the western Mentelle Basin offshore Western Australia. The erosion restoration model shows that erosion is confined within the rift margins, suggesting that rift structure has strongly influenced the evolution of the Denman and Scott ice streams.

  3. An Aquatic Journey toward Aeolis Mons (Mount Sharp): Sedimentary Rock Evidence observed by Mars Science Laboratory

    NASA Astrophysics Data System (ADS)

    Gupta, Sanjeev; Edgar, Lauren; Williams, Rebecca; Rubin, David; Yingst, Aileen; Lewis, Kevin; Kocurek, Gary; Anderson, Ryan; Dromart, Gilles; Edgett, Ken; Hardgrove, Craig; Kah, Linda; Mangold, Nicolas; Milliken, Ralph; Minitti, Michelle; Palucis, Marisa; Rice, Melissa; Stack, Katie; Sumner, Dawn; Williford, Ken

    2014-05-01

    Since leaving Yellowknife Bay (summer 2013), Mars Science Laboratory Curiosity has investigated a number of key outcrops as it traverses along the Rapid Transit Route toward the entry point to begin its investigations of the extensive rock outcrops at the base of Mount Sharp. Rover observations are characterizing the variability of lithologies and sedimentary facies along the traverse and establishing stratigraphic relationships with the aim of reconstructing depositional processes and palaeoenvironments. Here, we report on sedimentological and stratigraphic observations based on images from the Mastcam and MAHLI instruments at Shaler and the Darwin waypoint. The informally named Shaler outcrop, which forms part of the Glenelg member of the Yellowknife Bay formation [1] is remarkable for the preservation of a rich suite of sedimentary structures and architecture, and was investigated on sols 120-121 and 309-324. The outcrop forms a pebbly sandstone body that is ~0.7 m thick and extends for up to 20 m. Shaler is largely characterized by pebbly sandstone facies showing well-developed decimeter-scale trough cross-stratification. Bedding geometries indicate sub-critical angles of climb, resulting in preservation of only the lee slope deposits. The grain size, and the presence and scale of cross-stratification imply sediment transport and deposition by unidirectional currents in a fluvial sedimentary environment. Curiosity investigated the informally named Darwin waypoint between sols 390 and 401, making detailed Mastcam and MAHLI observations at two separate locations. The Darwin outcrop comprises light-toned sandstone beds separated by darker pebbly sandstones. MAHLI observations permit differentiation of distinct sedimentary facies. The Altar Mountain facies is a poorly sorted pebbly sandstone that is rich in fine pebbles. Pebbles are sub-angular to sub-rounded in shape and show no preferred orientation or fabric. Pebbles and sand grains show clast-to-clast contacts

  4. Modeling of the Sedimentary Interbedded Basalt Stratigraphy for the Idaho National Laboratory Probabilistic Seismic Hazard Analysis

    SciTech Connect

    Suzette Payne

    2006-04-01

    This report summarizes how the effects of the sedimentary interbedded basalt stratigraphy were modeled in the probabilistic seismic hazard analysis (PSHA) of the Idaho National Laboratory (INL). Drill holes indicate the bedrock beneath INL facilities is composed of about 1.1 km of alternating layers of basalt rock and loosely consolidated sediments. Alternating layers of hard rock and “soft” loose sediments tend to attenuate seismic energy greater than uniform rock due to scattering and damping. The INL PSHA incorporated the effects of the sedimentary interbedded basalt stratigraphy by developing site-specific shear (S) wave velocity profiles. The profiles were used in the PSHA to model the near-surface site response by developing site-specific stochastic attenuation relationships.

  5. Modeling of the Sedimentary Interbedded Basalt Stratigraphy for the Idaho National Laboratory Probabilistic Seismic Hazard Analysis

    SciTech Connect

    Suzette Payne

    2007-08-01

    This report summarizes how the effects of the sedimentary interbedded basalt stratigraphy were modeled in the probabilistic seismic hazard analysis (PSHA) of the Idaho National Laboratory (INL). Drill holes indicate the bedrock beneath INL facilities is composed of about 1.1 km of alternating layers of basalt rock and loosely consolidated sediments. Alternating layers of hard rock and “soft” loose sediments tend to attenuate seismic energy greater than uniform rock due to scattering and damping. The INL PSHA incorporated the effects of the sedimentary interbedded basalt stratigraphy by developing site-specific shear (S) wave velocity profiles. The profiles were used in the PSHA to model the near-surface site response by developing site-specific stochastic attenuation relationships.

  6. Fluvial geomorphic elements in modern sedimentary basins and their potential preservation in the rock record: A review

    NASA Astrophysics Data System (ADS)

    Weissmann, G. S.; Hartley, A. J.; Scuderi, L. A.; Nichols, G. J.; Owen, A.; Wright, S.; Felicia, A. L.; Holland, F.; Anaya, F. M. L.

    2015-12-01

    Since tectonic subsidence in sedimentary basins provides the potential for long-term facies preservation into the sedimentary record, analysis of geomorphic elements in modern continental sedimentary basins is required to understand facies relationships in sedimentary rocks. We use a database of over 700 modern sedimentary basins to characterize the fluvial geomorphology of sedimentary basins. Geomorphic elements were delineated in 10 representative sedimentary basins, focusing primarily on fluvial environments. Elements identified include distributive fluvial systems (DFS), tributive fluvial systems that occur between large DFS or in an axial position in the basin, lacustrine/playa, and eolian environments. The DFS elements include large DFS (> 30 km in length), small DFS (< 30 km in length), coalesced DFS in bajada or piedmont plains, and incised DFS. Our results indicate that over 88% of fluvial deposits in the evaluated sedimentary basins are present as DFS, with tributary systems covering a small portion (1-12%) of the basin. These geomorphic elements are commonly arranged hierarchically, with the largest transverse rivers forming large DFS and smaller transverse streams depositing smaller DFS in the areas between the larger DFS. These smaller streams commonly converge between the large DFS, forming a tributary system. Ultimately, most transverse rivers become tributary to the axial system in the sedimentary basin, with the axial system being confined between transverse DFS entering the basin from opposite sides of the basin, or a transverse DFS and the edge of the sedimentary basin. If axial systems are not confined by transverse DFS, they will form a DFS. Many of the world's largest rivers are located in the axial position of some sedimentary basins. Assuming uniformitarianism, sedimentary basins from the past most likely had a similar configuration of geomorphic elements. Facies distributions in tributary positions and those on DFS appear to display

  7. Preservation of overmature, ancient, sedimentary organic matter in carbonate concretions during outcrop weathering.

    PubMed

    Loyd, S J

    2017-01-01

    Concretions are preferentially cemented zones within sediments and sedimentary rocks. Cementation can result from relatively early diagenetic processes that include degradation of sedimentary organic compounds or methane as indicated by significantly (13) C-depleted or enriched carbon isotope compositions. As minerals fill pore space, reduced permeability may promote preservation of sediment components from degradation during subsequent diagenesis, burial heating and outcrop weathering. Discrete and macroscopic organic remains, macro and microfossils, magnetic grains, and sedimentary structures can be preferentially preserved within concretions. Here, Cretaceous carbonate concretions of the Holz Shale are shown to contain relatively high carbonate-free total organic carbon (TOC) contents (up to ~18.5 wt%) compared to the surrounding host rock (with <2.1 wt%). TOC increases with total inorganic carbon (TIC) content, a metric of the degree of cementation. Pyrite contents within concretions generally correlate with organic carbon contents. Concretion carbonate carbon isotope compositions (δ(13) Ccarb ) range from -22.5 to -3.4‰ (VPDB) and do not correlate strongly with TOC. Organic carbon isotope compositions (δ(13) Corg ) of concretions and host rock are similar. Thermal maturity data indicate that both host and concretion organic matter are overmature and have evolved beyond the oil window maturity stage. Although the organic matter in general has experienced significant oxidative weathering, concretion interiors exhibit lower oxygen indices relative to the host. These results suggest that carbonate concretions can preferentially preserve overmature, ancient, sedimentary organic matter during outcrop weathering, despite evidence for organic matter degradation genetic mechanisms. As a result, concretions may provide an optimal proxy target for characterization of more primary organic carbon concentrations and chemical compositions. In addition, these findings

  8. Paleogeographic implications of Tertiary sedimentary rocks within the northern Rawhide and Artillery Mountains, Arizona

    SciTech Connect

    Yarnold, J.C.; Dickinson, W.R. . Dept. of Geosciences)

    1993-04-01

    Geologic mapping and analysis of Oligocene-Miocene sedimentary rocks in the upper plate of the Buckskin-Rawhide detachment fault system (west-central Arizona) reveals a complex paleogeographic history during fault displacement. Within the study area, four upper-plate fault blocks are capped by homoclinal sedimentary sections that display fanning dip relationships indicating concurrent tilting and sedimentation. Four sedimentary assemblages recognized within the study area can be correlated between fault blocks. The basal assemblage consists of lacustrine rocks and interfingering fluvial strata composed of detritus derived from the granitic terrane surrounding the northern part of the study area; these sediments were deposited during the earliest stages of tilting of upper-plate fault blocks. The overlying lower assemblage consists of fine-grained lacustrine deposits, sandy conglomerate and breccia. During lower-assemblage deposition, mass-flow-dominated alluvial fans were shed from source areas consisting mainly of Mesozoic and Paleozoic rocks exposed to the south of the study area. Tilting of fault blocks continued during deposition of the lower assemblage and strongly affected dispersal patterns and lithofacies distributions. The middle assemblage consists of conglomerate and sandstone deposited by an extensive south-directed stream system that probably flowed off undistended parts of the hanging wall, across extended parts, and locally onto the footwall. The upper assemblage consists of sandy conglomerate deposited by a northeast-directed system of broad, shallow steams; these deposits display a variety of clast types, including Tertiary mylonitic, sedimentary, and volcanic rocks that were eroded from the upwarped footwall of the core complex and overlying klippen.

  9. Nuclear magnetic resonance in sedimentary rocks: Effect of proton desorption rate

    NASA Astrophysics Data System (ADS)

    Mendelson, Kenneth S.

    1982-09-01

    In a discussion of nuclear magnetic resonance of protons in the pore fluid of sedimentary rocks, Cohen and Mendelson assumed that the desorption rate of protons from the rock surface is much faster than the relaxation rate of the magnetization for protons on the surface. In the present paper it is shown that this assumption is not necessary and conditions are established under which the analysis of Cohen and Mendelson is valid.

  10. Benthic foraminiferal response to sedimentary disturbance in the Capbreton canyon (Bay of Biscay, NE Atlantic)

    NASA Astrophysics Data System (ADS)

    Duros, P.; Silva Jacinto, R.; Dennielou, B.; Schmidt, S.; Martinez Lamas, R.; Gautier, E.; Roubi, A.; Gayet, N.

    2017-02-01

    Living (Rose Bengal stained) and dead benthic foraminifera were investigated at 6 deep-sea sites sampled in the Capbreton canyon area (Bay of Biscay, France). Three sites were located along the canyon axis at 301 m, 983 m and 1478 m and 3 stations were positioned on adjacent terraces at 251 m, 894 m and 1454 m. Sedimentary features indicate that frequent sedimentary disturbances of different magnitudes occur along the Capbreton canyon axis and adjacent terraces. Such environmental conditions cause the presence of very particular benthic environments. Along the 6 studied sites, different foraminiferal responses to various sedimentary patterns are observed revealing the complexity of this canyon environment. Some sites (Gitan 3 (canyon axis), Gitan 5 (canyon axis) and Gitan 6 (terrace)) are characterized by moderate to low standing stocks and low diversity and are mainly dominated by pioneer taxa such as Fursenkoina brady, Reophax dentaliniformis and Technitella melo suggesting a recent response to turbidite deposits recorded at these sites. Others sites (Gitan 1 and Gitan 2) show extremely high standing stocks and are mainly dominated by the opportunistic Bolivina subaenariensis and Bulimina marginata. Such faunal characteristics belonging to a more advanced stage of ecosystem colonization indicates strongly food-enriched sediment but extremely unstable conditions. Moderate standing stocks and diverse assemblage composed of species such as Uvigerina mediterranea and U. peregrina has only been observed at the terrace site Gitan 4. More stable sedimentary conditions recorded at this terrace seem to be suitable to the development of a dense and diverse foraminiferal community. Numerous neritic allochtonous species were observed in the dead foraminiferal fauna. These allochthonous species mainly originate from shelf areas (<60 m).

  11. Synchronisation of sedimentary records using tephra: A postglacial tephrochronological model for the Chilean Lake District

    NASA Astrophysics Data System (ADS)

    Fontijn, Karen; Rawson, Harriet; Van Daele, Maarten; Moernaut, Jasper; Abarzúa, Ana M.; Heirman, Katrien; Bertrand, Sébastien; Pyle, David M.; Mather, Tamsin A.; De Batist, Marc; Naranjo, Jose-Antonio; Moreno, Hugo

    2016-04-01

    Well-characterised tephra horizons deposited in various sedimentary environments provide a means of synchronising sedimentary archives. The use of tephra as a chronological tool is however still widely underutilised in southern Chile and Argentina. In this study we develop a postglacial tephrochronological model for the Chilean Lake District (ca. 38 to 42°S) by integrating terrestrial and lacustrine records. Tephra deposits preserved in lake sediments record discrete events even if they do not correspond to primary fallout. By combining terrestrial with lacustrine records we obtain the most complete tephrostratigraphic record for the area to date. We present glass geochemical and chronological data for key marker horizons that may be used to synchronise sedimentary archives used for palaeoenvironmental, palaeoclimatological and palaeoseismological purposes. Most volcanoes in the studied segment of the Southern Volcanic Zone, between Llaima and Calbuco, have produced at least one regional marker deposit resulting from a large explosive eruption (magnitude ≥ 4), some of which now have a significantly improved age estimate (e.g., the 10.5 ka Llaima Pumice eruption from Llaima volcano). Others, including several units from Puyehue-Cordón Caulle, are newly described here. We also find tephra related to the Cha1 eruption from Chaitén volcano in lake sediments up to 400 km north from source. Several clear marker horizons are now identified that should help refine age model reconstructions for various sedimentary archives. Our chronological model suggests three distinct phases of eruptive activity impacting the area, with an early-to-mid-Holocene period of relative quiescence. Extending our tephrochronological framework further south into Patagonia will allow a more detailed evaluation of the controls on the occurrence and magnitude of explosive eruptions throughout the postglacial.

  12. Fault Zone Hydrogeology of Crystalline and Sedimentary Aquifers in Arid Regions: The Case Sinai Peninsula, Egypt.

    NASA Astrophysics Data System (ADS)

    Ahmed, M.; Mohamed, L.; Sultan, M.; Farag, A. Z. A.

    2015-12-01

    Structural control on the groundwater flow in arid regions is still poorly understood. Understanding the distribution of structural discontinuities (i.e. faults, joints and shear zones), their cross cutting relationships, and their relation with the regional hydraulic gradient are critical for deciphering the complexity of water resources distribution in the highly fractured crystalline and sedimentary aquifers in Sinai. In order to achieve that, we conducted an integrated approach using remote sensing, geophysical and hydrogeological datasets: (1) identification of the spatial and temporal rainfall events using Tropical Rainfall Measuring Mission (TRMM) data; (2) delineation of major faults and shear zones using Landsat 8 and ASTER image ratioing, geological datasets and field investigation; (3) generation of a normalized difference ratio image using Envisat radar images before and after the rain events to identify preferential water-channeling discontinuities in the crystalline terrain; (4) validation of the water-channeling discontinuities using Very Low Frequency (VLF) method; (5) generation of regional groundwater flow and isotopic (18O and 2H ) distribution maps for the sedimentary aquifer and an approximation flow map for the crystalline aquifer; (6) developing a conceptual model for the groundwater flow in the fractured crystalline and sedimentary aquifers; (7) testing the model accuracy using Vertical Electrical Sounding (VES) method in seven locations. Our findings include: (1) in the crystalline aquifer, discontinuities that are sub-parallel to groundwater flow direction act as preferred pathways for groundwater flow, whereas those that intersect groundwater flow directions at high angles act as barriers causing considerable groundwater accumulations at the upstream side; (2) in the sedimentary aquifer, high angle E-W discontinuities (i.e. Themed shear zone and Sinai Hinge Belt) cause a considerable groundwater elevation, redirection of the groundwater

  13. Composition of dispersed sedimentary matter and fluxes in the water column of the Caspian Sea

    NASA Astrophysics Data System (ADS)

    Lisitzin, A. P.; Lukashin, V. N.

    2015-09-01

    This article presents the first data on the chemical composition of dispersed matter from sediment traps with analysis of the sedimentary components that constitute suspended particulate matter (amorphous silica, organic matter (OM), carbonates, and lithogenic matter). It is established that the annual variability of fluxes demonstrates its seasonal growth in spring and summer. High fluxes of these components over the northern and southern slopes of the Derbent Basin are determined by deposition of material from the nepheloid layer formed by the contour current.

  14. Direct stable isotope porewater equilibration and identification of groundwater processes in heterogeneous sedimentary rock.

    PubMed

    David, Katarina; Timms, Wendy; Baker, Andy

    2015-12-15

    The off-axis integrated cavity output spectrometry (ICOS) method to analyse porewater isotopic composition has been successfully applied over the last decade in groundwater studies. This paper applies the off-axis ICOS method to analyse the porewater isotopic composition, attempts to use the isotopic shift in groundwater values along with simple geochemical mixing model to define the groundwater processes in the Sydney Basin, Australia. Complementary data included geophysical, hydrogeological, geochemical, and mineralogical investigations. Porewater from core samples were analysed for δ(18)O and δ(2)H from various sedimentary units in the Basin and compared to endpoint water members. Stable δ(18)O and δ(2)H values of porewaters in the Basin (-9.5 to 2.8‰ for δ(18)O and -41.9 to 7.9‰ for δ(2)H) covered a relatively narrow range in values. The variability in water isotopes reflects the variability of the input signal, which is the synoptic variability in isotopic composition of rainfall, and to a minor extent the subsequent evaporation. The porosity, bulk density and mineralogy data demonstrate the heterogeneity that adds the complexity to variations in the isotope profile with depth. The source of chloride in the sedimentary sequence was related to rock-water and cement/matrix-water interaction rather than to evaporation. The heterogeneous character of the sedimentary rock strata was supported by a change in pore pressures between units, density and variability in rock geochemical analyses obtained by using X-ray fluorescence (XRF) and X-ray power diffraction analyses. This research identified distinct hydrogeological zones in the Basin that were not previously defined by classic hydrogeological investigations. Isotopic signature of porewaters along the detailed vertical profile in combination with mineralogical, geochemical, geophysical and hydrogeological methods can provide useful information on groundwater movement in deep sedimentary environments. The

  15. The sedimentary and crustal velocity structure of Makarov Basin and adjacent Alpha Ridge

    NASA Astrophysics Data System (ADS)

    Evangelatos, John; Funck, Thomas; Mosher, David C.

    2017-01-01

    This study examines the velocity structure of Makarov Basin and the adjacent Alpha Ridge to determine the tectonic origins of these features and link them to the larger Amerasia Basin. Seismic data from sonobuoys distributed along a 650 km-long line extending from Alpha Ridge and across Makarov Basin to the Lomonosov Ridge were analyzed for this purpose. Forward modelling of traveltimes, supported by coincident multi-channel seismic reflection and shipborne gravity data, were used to determine the P-wave velocity structure along the line. The sedimentary cover averages 0.5 km-thick on Alpha Ridge and 1.9 km-thick in Makarov Basin, but reaches up to 5 km-thick at the base of Lomonosov Ridge. Velocities in the sedimentary section range from 1.6 to 4.3 km s- 1. As suggested by relatively high velocities, interbedded volcaniclastic or volcanic rock may occur in the deep sedimentary section. The shallow basement of Alpha Ridge (3.3 to 3.6 km s- 1) is characterized by semi-continuous high amplitude reflections and is interpreted as volcanic rock possibly intercalated with sedimentary rock. Velocities do not vary significantly in the upper and mid-crustal layers between Alpha Ridge and Makarov Basin. Total crustal thickness decreases from 27 km beneath Alpha Ridge to 5 km-thick in Makarov Basin then thickens to > 20 km over a short distance as part of Lomonosov Ridge. The crustal structure of Alpha Ridge is consistent with previous studies suggesting that the Alpha-Mendeleev ridge complex is part of a large igneous province (LIP) with thick igneous crust. The lack of change in crustal velocities between Alpha Ridge and Makarov Basin suggests that the basin, at least partly, either formed during or was influenced by LIP-related magmatism. The rapid transition of crustal thicknesses from Makarov Basin to Lomonosov Ridge supports the interpretation that this section of the ridge is a transform margin.

  16. Overpressure Evolution during Sedimentary Basin Diagenesis: Implications for Hydrocarbon Transport By Solitary Waves

    NASA Astrophysics Data System (ADS)

    Joshi, A.; Appold, M. S.

    2014-12-01

    Recent research has shown solitary waves to be capable of transporting fluids through porous media at rates orders of magnitude faster than predicted from Darcy's law. Solitary waves are expressed as regions of high fluid pressure and porosity. The waves form and propagate where permeability is a sensitive function of effective stress, fluid pressure approaches lithostatic pressure, and the rate of fluid pressure generation is rapid compared to the rate of fluid pressure diffusion. The purpose of the present study was to investigate the pressure generation rates that can develop in a sedimentary basin over a range of possible geologic conditions so that the potential for solitary wave formation can be assessed. Pressure generation rates were calculated for a generic sedimentary basin by constructing a two-dimensional numerical model that treated sediment deposition, compaction, heat flow, kerogen maturation, hydrocarbon formation, and the flow of water, oil, and gas. The results showed compaction disequilibrium and hydrocarbon formation to be the two principal causes of pressure generation, respectively. Pressure generation rates for typical sedimentary basinal conditions were found to be on the order of 1's of Pa/year, up to a maximum of ~400 Pa/year under the most favorable pressure generating conditions. These pressure generation rates would be sufficient to form oil-saturated solitary waves but too low to form methane-saturated solitary waves because of the higher rate of methane pressure diffusion compared to oil, due to methane's lower viscosity. To form methane-saturated solitary waves, pressure generation rates of at least ~1800 Pa/year are needed, which are unlikely to be produced by sedimentary basin diagenetic processes, but could possibly be produced by earthquakes.

  17. Long Term Trends in Subantarctic Nutrient Consumption: Evidence from Sedimentary and Diatom-Bound Nitrogen Isotopes

    NASA Astrophysics Data System (ADS)

    Bedsole, P.

    2014-12-01

    It has been proposed that the long term increase in Subantarctic opal export during glacial periods, centered around 1 Ma, is related to enhanced iron deposition and, potentially, carbon dioxide drawdown. New bulk sedimentary and diatom-bound nitrogen isotope records are used in combination with opal accumulation data from ODP Site 1090 to investigate controls on export production over the last 3 Ma. Sedimentary nitrogen content tracks opal during periods of high iron accumulation, especially after ~1 Ma. Bulk sedimentary nitrogen isotope trends are negatively correlated with sedimentary N-content and opal accumulation. This may be signal weaker nutrient consumption during times of high production, perhaps as a result of enhanced vertical nutrient supply. Alternatively, this variation in bulk, where high values occur in organic poor intervals, is consistent with other evidence for nitrogen isotopic alteration during periods of low export to the seafloor. The diatom-bound nitrogen isotope record does not have a clear relationship with opal or iron accumulation. A long term shift in the diatom-bound N isotope values is apparent, where the average diatom-bound δ15N from 0.5-1 Ma is 4.4 ‰, and from 2-2.6 Ma is 5.9 ‰. This decrease may reflect long-term changes in nitrate availability. A first order comparison to planktonic/benthic carbon isotopic gradients suggests that enhanced vertical mixing may explain the observed productivity peaks and lower overall diatom-bound N isotope values in the interval centered around 1 Ma.

  18. The Carboniferous carbon isotope record from sedimentary organic matter: can we disentangle the carbon cycle?

    NASA Astrophysics Data System (ADS)

    Davies, S. J.; Bennett, C. E.; Leng, M. J.; Kearsey, T.; Marshall, J. E.; Millward, D.; Reeves, E. J.; Snelling, A.; Sherwin, J. E.

    2014-12-01

    A comprehensive analysis of the δ13C composition of sedimentary organic matter from Euramerican Carboniferous successions indicates there are significant shifts in δ13C through this key time interval. Our studies have revealed that, at an individual location, the source and delivery mechanism of the sediment contribute to the type of organic matter preserved and, in turn this influences the measured δ13C values from bulk sedimentary organic matter of organic matter. In general, where marine-derived organic matter is dominant in these Carboniferous successions then δ13C values are characteristically lower compared to the higher values encountered where terrestrial plant-derived material is most abundant. The implication of these observations is that an apparent carbon isotope excursion identified from the bulk organic matter may reflect a change in transport processes, or depositional environment, rather than a perturbation in the global carbon cycle. In our most recent studies, however, we compare δ13C values from specific wood fragments and bulk sedimentary organic matter from non-marine, marine basinal, and marine shelfal successions from the earliest Mississippian through to the early Pennsylvanian. These data indicate that early Mississippian δ13C of organic matter is far less negative (around -22%0) than material of Late Mississippian age (around -26%0), however by the early Pennsylvanian, δ13C values return to -22%0. There are some δ13C data from brachiopod carbonate from this time interval and similar shifts are indicated. Our data are beginning to address whether we can identify a primary carbon cycle signal from the Carboniferous record using δ13C from a range of sedimentary environments. If we can, there are still questions around what the record is telling us about the global carbon cycle during a period when plant groups, including lycopods and seed ferns, rapidly diversified.

  19. Biomass Burning, Long-Range Atmospheric Transport and the Sedimentary Record of Plant Wax Biomarkers

    NASA Astrophysics Data System (ADS)

    Weber, J. C.; Conte, M. H.

    2007-12-01

    Sedimentary distributions of plant leaf wax molecular and isotopic composition can provide detailed information about past terrestrial ecosystem structure and its variability in response to climatic forcing. However, in many locales (e.g. marine sediments, high elevation lakes), sedimentary plant waxes are derived primarily from atmospheric deposition rather than from local fluvial input or direct runoff. Thus, an understanding of wax atmospheric transport and deposition is essential for accurate interpretation of the sedimentary signal. In this talk we synthesize results from our studies of wax aerosol composition and atmospheric transport at strategically located sites (Northern Alaska, Maine, Florida, Bermuda, Barbados, French Guiana) that sample continental air masses passing over major terrestrial ecosystems (tundra, North American boreal, temperate and southern pine forests, North African desert grasslands, Amazon rain forest). Wax aerosols in boundary layer air masses reflect a large regionally integrated source signal. Over the North Atlantic, the long-range atmospheric transport of plant waxes is essentially uncorrelated with episodes of high African dust transport. Rather, the highest plant wax aerosol concentrations are clearly associated with continental air masses that are laden with smoke from biomass burning, which enhances long-range transport both by the process of steam distillation of wax and other easily volatilized compounds off living (moisture-rich) vegetation in the advancing front of the fire and by deep atmospheric convection, which efficiently injects re- condensed particles into the lower troposphere where they can be most efficiently transported by high altitude winds. The direct linkage between enhanced long-range atmospheric transport of plant waxes and biomass burning suggests that the wax sedimentary record in localities dominated by atmospheric input strongly co-varies with climate-driven changes in fire frequency and is

  20. Recognizing the threshold magnetic anisotropy for inclination shallowing: Implications for correcting inclination errors of sedimentary rocks

    NASA Astrophysics Data System (ADS)

    Li, Yongxiang; Wang, Shipeng; Fu, Shaoying; Jiao, Wenjun

    2014-05-01

    Post-depositional compaction is an integral part of sedimentary rock formation and thus has been reasonably deemed as a major culprit for the long-recognized inclination-shallowing problem in sedimentary rocks. Although theoretical treatment elegantly envisions magnetic anisotropy (or oblate fabrics) to correspond to the degree of compaction and the magnitude of inclination flattening, such correspondence has rarely been seen in nature quantitavely, which leaves the possibility of misidentification and/or over-correction for inclination shallowing using magnetic anisotropy. This is because the extent to which oblate magnetic fabrics are developed strongly enough for inclination to start becoming shallow is not yet known. Here, we present sedimentary paleomagnetic data from two ~6 m long gravity cores GHE24L and GHE27L from the northern slope of the South China Sea to examine the down-core changes in magnetic anisotropy and inclinations, and to explore the possible connection between the two parameters. The results show that oblate fabrics are dominantly developed at depths >~2m and the degree of anisotropy displays an overall gradual increase with depth. Inclination shallowing occurs in the > 5m segment of the relatively distal core GHE27L and the amount of shallowing largely correlates with the degree of anisotropy, suggesting a causal relation between the development of magnetic anisotropy and the degree of inclination shallowing. Examination of down-core changes in inclination and magnetic anisotropy suggests that a threshold anisotropy of PAMS~1.04 and PAAR~1.10 exists for inclination shallowing in the cores. For PAAR<1.10, over-correction is mostly negligible, but can amount >10° if particle anisotropy is <1.4. This study provides strong field evidence that complements and substantiates the theoretical model and suggests that the threshold anisotropy can be used as a first-order criterion to identify inclination errors of some sedimentary rocks.

  1. UAS-based quantification of sedimentary body changes at Langgriesgraben, Styria, Austria

    NASA Astrophysics Data System (ADS)

    Schöttl, Stefan; Seier, Gernot; Rascher, Eric; Sulzer, Wolfgang; Sass, Oliver

    2016-04-01

    The creek's sedimentary body at Langgriesgraben is characterized by inconstant but recurring earth surface changes. Mass transport and deposition occur partly spontaneously and endanger primary infrastructure, in particular a main road. It is often mentioned in literature that the use of small and lightweight UAS is promising. To contribute to that, this study focuses on the documentation and quantification of carried sedimentary material by using a hexacopter in a high alpine environment. The images which were captured on two different dates, allow generating orthophotos and DEMs. The comparison of these derivatives enables a deeper understanding of the sedimentary body and its conditions. Our specific study area is a part of a bigger research area of another research project (Sedyn-X). One of the main goals of that project is to create a conceptual model of the sedimentary cascade for the entire Johnsbachtal catchment and to quantify geomorphic processes (e.g. erosion, transport and rearrangement of sediments). Therefore Terrestrial Laser Scanning recordings are performed as well. Through the generated surface models from different eras, changes in surface and volume can be quantified. The photogrammetric surface models can be compared with almost simultaneous ALS and TLS recordings. Apart from that, the outcomes will provide hard facts for decision-makers. The UAS related processing steps and methods (e.g. DGPS, SfM) are more or less established and well-known, but the applicability of UAS for recording feasible data, has to be proved constantly. We assume that our results will answer concrete questions and thus reduce expected damage and costs.

  2. Impact of sedimentary heterogenities and sinuosity on river -aquifer exchanges in a meandering alluvial plain.

    NASA Astrophysics Data System (ADS)

    Rivière, A.; Maillot, M.; Weill, P.; Goblet, P.; Ors, F.

    2015-12-01

    A coupled sedimentary and hydrogeological model is used to quantify the impact of sedimentary heterogeneities and sinuosity on groundwater fluxes in an alluvial plain deposited by a meandering fluvial system. A 3D heterogeneous alluvial plain model is built with the stochastic/process-based model FLUMY, that simulates the evolution and the sedimentary processes of a meandering channel and its associated deposits. The resulting sedimentary blocks are translated in terms of hydrodynamic parameters (hydrofacies) and used in the 3D transient water transport model METIS. The simulated domain is 10 m-thick and at a pluri-kilometric horizontal scale, allowing considering several meanders. A head gradient between the upstream and downstream limits is imposed. The river is considered as a constant-head boundary that decreases linearly along the channel centerline. A zero-flux condition is prescribed on the other boundaries. Several cases are studied, including different degrees of sinuosity and different configurations of sediment heterogeneity: (i) a homogeneous sandy aquifer (ii) single mud-filled oxbow lake in a sandy porous media, (iii) several mud-filled oxbow lakes in a sandy porous media, and (iv) "fully" heterogeneous alluvial plain including fine-grained overbank deposits, sandy point bars, mudplugs and sandy crevasse plays. We quantify the exchange rates and directions between the river and the aquifer along the channel centerline, the piezometric evolution and the water residence time in the heterogeneous alluvial plain. This original method can improve our understanding of the functioning of alluvial corridors and evaluate the relevance of taking into account the structural heterogeneity of alluvial plains in larger regional hydrogeological models.

  3. Isotopic Equilibration Between Sulfide and Organic Matter: Implications for Records of Sedimentary δ34S.

    NASA Astrophysics Data System (ADS)

    Raven, M. R.; Sessions, A. L.; Adkins, J. F.; Fischer, W. W.

    2015-12-01

    Records of the sulfur-isotopic composition of sedimentary pyrite have been used to constrain the evolutionary timing of major metabolic pathways, the size of the marine sulfate reservoir, and the redox balance of the planet. It remains a major challenge, however, to explain the enormous range of pyrite δ34S values in the literature and their typical ~10‰ offset relative to sedimentary organic S. We investigate the development of pyrite and organic S records in Santa Barbara Basin, which has suboxic bottom water and high (≥4 wt%) organic matter burial. Concentration and δ34S profiles of major sulfur species (sulfate, sulfide, elemental S, proto-kerogen, pyrite, and extractable organic matter) suggest the occurrence of S-isotope exchange between porewater sulfide and organic S, so we conducted laboratory experiments to test organic S exchangeability with 34S-labelled sulfide-polysulfide solutions. We found that both extractable and proto-kerogen organic matter incorporated significant amounts of label within days, supporting the feasibility of equilibration between sulfide and organic matter in the environment. Unlike organic S, pyrite δ34S values in Santa Barbara Basin sediments are up to 30‰ lower than those for porewater sulfide. We hypothesize that this strongly 34S-depleted pyrite reflects the immediate products of bacterial sulfate reduction at organic-rich structures like microbial biofilms or aggregates and suggest that this δ34S difference between porewater sulfide and pyrite may be a more common than previously recognized. Pyrite δ34S values are not necessarily reflective of porewater sulfide δ34S, suggesting that this common assumption should be revisited. Sedimentary pyrite and organic S are potentially powerful and complementary archives of environmental information. To meaningfully interpret these records, it is essential that we take into account the complex processes affecting sedimentary pyrite and organic sulfur δ34S in modern sediments.

  4. Sedimentary Facies Mapping Based on Tidal Channel Network and Topographic Features

    NASA Astrophysics Data System (ADS)

    Ryu, J. H.; Lee, Y. K.; Kim, K.; Kim, B.

    2015-12-01

    Tidal flats on the west coast of Korea suffer intensive changes in their surface sedimentary facies as a result of the influence of natural and artificial changes. Spatial relationships between surface sedimentary facies distribution and benthic environments were estimated for the open-type Ganghwa tidal flat and semi closed-type Hwangdo tidal flat, Korea. In this study, we standardized the surface sedimentary facies and tidal channel index of the channel density, distance, thickness and order. To extract tidal channel information, we used remotely sensed data, such as those from the Korea Multi-Purpose Satellite (KOMPSAT)-2, KOMPSAT-3, and aerial photographs. Surface sedimentary facies maps were generated based on field data using an interpolation method.The tidal channels in each sediment facies had relatively constant meandering patterns, but the density and complexity were distinguishable. The second fractal dimension was 1.7-1.8 in the mud flat, about 1.4 in the mixed flat, and about 1.3 in the sand flat. The channel density was 0.03-0.06 m/m2 in the mud flat and less than 0.02 m/m2 in the mixed and sand flat areas of the two test areas. Low values of the tidal channel index, which indicated a simple pattern of tidal channel distribution, were identified at areas having low elevation and coarse-grained sediments. By contrast, high values of the tidal channel index, which indicated a dendritic pattern of tidal channel distribution, were identified at areas having high elevation and fine-grained sediments. Surface sediment classification based on remotely sensed data must circumspectly consider an effective critical grain size, water content, local topography, and intertidal structures.

  5. Assessment of undiscovered conventional oil and gas resources of the Western Canada Sedimentary Basin, Canada, 2012

    USGS Publications Warehouse

    Higley, Debra

    2013-01-01

    The U.S. Geological Survey recently completed a geoscience-based assessment of undiscovered oil and gas resources of provinces within the Western Canada Sedimentary Basin. The Western Canada Sedimentary Basin primarily comprises the (1) Alberta Basin Province of Alberta, eastern British Columbia, and the southwestern Northwest Territories; (2) the Williston Basin Province of Saskatchewan, southeastern Alberta, and southern Manitoba; and (3) the Rocky Mountain Deformed Belt Province of western Alberta and eastern British Columbia. This report is part of the U.S. Geological Survey World Petroleum Resources Project assessment of priority geologic provinces of the world. The assessment was based on geoscience elements that define a total petroleum system (TPS) and associated assessment unit(s). These elements include petroleum source rocks (geochemical properties and petroleum generation, migration, and accumulation), reservoir description (reservoir presence, type, and quality), and petroleum traps (trap and seal types, and timing of trap and seal formation relative to petroleum migration). Using this framework, the Elk Point-Woodbend Composite TPS, Exshaw-Fernie-Mannville Composite TPS, and Middle through Upper Cretaceous Composite TPS were defined, and four conventional assessment units within the total petroleum systems were quantitatively assessed for undiscovered resources in the Western Canada Sedimentary Basin.

  6. Case study of a sabkha sedimentary environment: Mallahat al Bariquah, Libya

    SciTech Connect

    Krason, J.

    1987-05-01

    The importance of the sabkha sedimentary environment for formation and/or accumulation of hydrocarbons, salts, and various metalliferous mineral deposits has been recognized by many geologists. A sabkha in which sedimentation and the formation of salt deposits and hydrocarbons is in progress is located along the Mediterranean Sea coast, in northwestern Libya and northeastern Tunisia. The sabkha Mallahat al Bariquah was drilled in a regular grid at 1-km spacing; 63 holes have been completed. The sabkha and its vicinity were geologically mapped (1:20,000). Several hundred core and loose rock samples were thoroughly examined with regard to the lithology, mineralogy, paleontology, and chemical composition. The chemistry of brine from each drill hole and solar pan was determined. Three 24-hour pumping tests were performed, and the hydrogeological conditions of the sabkha were analyzed in detail. Economically valuable bedded salt reserves of 170,800,000 MT of NaCl were discovered and proven. Additionally, over 30 million MT of potassium, magnesium, and sodium salts including bromides are recoverable from the brine. Although marine-coastal sabkhas are common, the extensive scope of this study is unique. Mallahat al Bariquah sabkha is not unique with regard to its geographic, climatic, or sedimentary environments. Therefore, Mallahat al Bariquah can be considered as a model applicable in exploration for and study of similar sedimentary environments in other geographic regions and older geologic epochs.

  7. Areal distribution of sedimentary facies determined from seismic facies analysis and models of modern depositional systems

    SciTech Connect

    Seramur, K.C.; Powell, R.D.; Carpenter, P.J.

    1988-01-01

    Seismic facies analysis was applied to 3.5-kHz single-channel analog reflection profiles of the sediment fill within Muir Inlet, Glacier Bay, southeast Alaska. Nine sedimentary facies have been interpreted from seven seismic facies identified on the profiles. The interpretations are based on reflection characteristics and structural features of the seismic facies. The following reflection characteristics and structural features are used: reflector spacing, amplitude and continuity of reflections, internal reflection configurations, attitude of reflection terminations at a facies boundary, body geometry of a facies, and the architectural associations of seismic facies within each basin. The depositional systems are reconstructed by determining the paleotopography, bedding patterns, sedimentary facies, and modes of deposition within the basin. Muir Inlet is a recently deglaciated fjord for which successive glacier terminus positions and consequent rates of glacial retreat are known. In this environment the depositional processes and sediment characteristics vary with distance from a glacier terminus, such that during a retreat a record of these variations is preserved in the aggrading sediment fill. Sedimentary facies within the basins of lower Muir Inlet are correlated with observed depositional processes near the present glacier terminus in the upper inlet.

  8. A multivariate geostatistical methodology to delineate areas of potential interest for future sedimentary gold exploration

    PubMed Central

    Goovaerts, P.; Albuquerque, Teresa; Antunes, Margarida

    2015-01-01

    This paper describes a multivariate geostatistical methodology to delineate areas of potential interest for future sedimentary gold exploration, with an application to an abandoned sedimentary gold mining region in Portugal. The main challenge was the existence of only a dozen gold measurements confined to the grounds of the old gold mines, which precluded the application of traditional interpolation techniques, such as cokriging. The analysis could, however, capitalize on 376 stream sediment samples that were analyzed for twenty two elements. Gold (Au) was first predicted at all 376 locations using linear regression (R2=0.798) and four metals (Fe, As, Sn and W), which are known to be mostly associated with the local gold’s paragenesis. One hundred realizations of the spatial distribution of gold content were generated using sequential indicator simulation and a soft indicator coding of regression estimates, to supplement the hard indicator coding of gold measurements. Each simulated map then underwent a local cluster analysis to identify significant aggregates of low or high values. The one hundred classified maps were processed to derive the most likely classification of each simulated node and the associated probability of occurrence. Examining the distribution of the hot-spots and cold-spots reveals a clear enrichment in Au along the Erges River downstream from the old sedimentary mineralization. PMID:27777638

  9. Estimate of the Geothermal Energy Resource in the Major Sedimentary Basins in the United States (Presentation)

    SciTech Connect

    Esposito, A.; Porro, C.; Augustine, C.; Roberts, B.

    2012-09-01

    Because most sedimentary basins have been explored for oil and gas, well logs, temperatures at depth, and reservoir properties such as depth to basement and formation thickness are well known. The availability of this data reduces exploration risk and allows development of geologic exploration models for each basin. This study estimates the magnitude of recoverable geothermal energy from 15 major known U.S. sedimentary basins and ranks these basins relative to their potential. The total available thermal resource for each basin was estimated using the volumetric heat-in-place method originally proposed by (Muffler, 1979). A qualitative recovery factor was determined for each basin based on data on flow volume, hydrothermal recharge, and vertical and horizontal permeability. Total sedimentary thickness maps, stratigraphic columns, cross sections, and temperature gradient information was gathered for each basin from published articles, USGS reports, and state geological survey reports. When published data were insufficient, thermal gradients and reservoir properties were derived from oil and gas well logs obtained on oil and gas commission databases. Basin stratigraphy, structural history, and groundwater circulation patterns were studied in order to develop a model that estimates resource size, temperature distribution, and a probable quantitative recovery factor.

  10. Advanced Horizontal Well Recirculation Systems for Geothermal Energy Recovery in Sedimentary and Crystalline Formations

    SciTech Connect

    Bruno, Mike S.; Detwiler, Russell L.; Lao, Kang; Serajian, Vahid; Elkhoury, Jean; Diessl, Julia; White, Nicky

    2012-12-13

    There is increased recognition that geothermal energy resources are more widespread than previously thought, with potential for providing a significant amount of sustainable clean energy worldwide. Recent advances in drilling, completion, and production technology from the oil and gas industry can now be applied to unlock vast new geothermal resources, with some estimates for potential electricity generation from geothermal energy now on the order of 2 million megawatts. The primary objectives of this DOE research effort are to develop and document optimum design configurations and operating practices to produce geothermal power from hot permeable sedimentary and crystalline formations using advanced horizontal well recirculation systems. During Phase I of this research project Terralog Technologies USA and The University of California, Irvine (UCI), have completed preliminary investigations and documentation of advanced design concepts for paired horizontal well recirculation systems, optimally configured for geothermal energy recovery in permeable sedimentary and crystalline formations of varying structure and material properties. We have also identified significant geologic resources appropriate for application of such technology. The main challenge for such recirculation systems is to optimize both the design configuration and the operating practices for cost-effective geothermal energy recovery. These will be strongly influenced by sedimentary formation properties, including thickness and dip, temperature, thermal conductivity, heat capacity, permeability, and porosity; and by working fluid properties.

  11. Modern sedimentary facies of the open Pacific coast and Pleistocene analogs from Montery Bay, California

    USGS Publications Warehouse

    Dupre, W.R.; Clifton, H.E.; Hunter, R.E.; Field, Michael E.; Field, Michael E.; ,

    1980-01-01

    Depositional processes and sedimentary structures of wave-dominated Pacific coastal environments vary systematically with water depth. The depth-limited open-coast facies identifiable by their sedimentary structures are the inner shelf, barred or nonbarred nearshore, beach, and coastal dune facies. These facies are most commonly preserved in shallowing-upward progradational sequences. The vertical sequence of sedimentary structures preserved in marine terrace deposits in the northern Monterey Bay region is very similar to that predicted on the basis of the modern facies. Few marine sediments deposited during the marine transgression that accompanied rising sea level were preserved. Most of the the marine and eolian sediments form a progradational sequence deposited mainly during intervals of falling sea level. In contrast, the sediments that form the adjacent fluvial terraces were deposited mainly during periods of rising sea level and became entrenched during the subsequent lowering of sea level. In combination, these fluvial, marine, and eolian deposits provide a record of a complete eustatic cycle. The recognition of the role of changing sea level in controlling patterns of coastal sedimentation and landform development during the Quaternary allows the development of a generalized model for Quaternary sedimentation along a wave-dominated coastline. The application of this model has aided in the interpretation of older Pleistocene sediments in the region (e.g. the Aromas Sand). It also has resulted in the recognition of at least eleven glacio-eustatic cycles preserved in the stratigraphic record of the Monterey Bay area during the Quaternary.

  12. Sedimentary geology of the middle Carboniferous of the Donbas region (Dniepr-Donets Basin, Ukraine).

    PubMed

    van Hinsbergen, Douwe J J; Abels, Hemmo A; Bosch, Wolter; Boekhout, Flora; Kitchka, Alexander; Hamers, Maartje; van der Meer, Douwe G; Geluk, Mark; Stephenson, Randell A

    2015-03-20

    The Paleozoic Dniepr-Donets Basin in Belarus, Ukraine, and Russia forms a major hydrocarbon province. Although well- and seismic data have established a 20 km thick stratigraphy, field-studies of its sediments are scarce. The inverted Donbas segment (Ukraine) exposes the middle Carboniferous part of the basin's stratigraphy. Here, we provide detailed sedimentological data from 13 sections that cover 1.5 of the total of 5 km of the Bashkirian and Moscovian stages and assess the paleoenvironment and paleo-current directions. Middle Carboniferous deposition occurred in a shelf environment, with coal deposition, subordinate fluvial facies, and abundant lower and middle shoreface facies, comprising an intercalated package of potential source and reservoir rocks. Sedimentary facies indicate a paleodepth range from below storm wave base to near-coastal swamp environments. Sedimentation and subsidence were hence in pace, with subtle facies changes likely representing relative sea-level changes. Paleocurrent directions are remarkably consistently southeastward in time and space in the different sedimentary facies across the Donbas Fold Belt, illustrating a dominant sedimentary infill along the basin axis, with little basin margin influence. This suggests that the middle Carboniferous stratigraphy of the Dniepr-Donets basin to the northwest probably contains significant amounts of fluvial sandstones, important for assessing hydrocarbon reservoir potential.

  13. An integrated insight into the response of sedimentary microbial communities to heavy metal contamination

    PubMed Central

    Yin, Huaqun; Niu, Jiaojiao; Ren, Youhua; Cong, Jing; Zhang, Xiaoxia; Fan, Fenliang; Xiao, Yunhua; Zhang, Xian; Deng, Jie; Xie, Ming; He, Zhili; Zhou, Jizhong; Liang, Yili; Liu, Xueduan

    2015-01-01

    Response of biological communities to environmental stresses is a critical issue in ecology, but how microbial communities shift across heavy metal gradients remain unclear. To explore the microbial response to heavy metal contamination (e.g., Cr, Mn, Zn), the composition, structure and functional potential of sedimentary microbial community were investigated by sequencing of 16S rRNA gene amplicons and a functional gene microarray. Analysis of 16S rRNA sequences revealed that the composition and structure of sedimentary microbial communities changed significantly across a gradient of heavy metal contamination, and the relative abundances were higher for Firmicutes, Chloroflexi and Crenarchaeota, but lower for Proteobacteria and Actinobacteria in highly contaminated samples. Also, molecular ecological network analysis of sequencing data indicated that their possible interactions might be enhanced in highly contaminated communities. Correspondently, key functional genes involved in metal homeostasis (e.g., chrR, metC, merB), carbon metabolism, and organic remediation showed a higher abundance in highly contaminated samples, indicating that bacterial communities in contaminated areas may modulate their energy consumption and organic remediation ability. This study indicated that the sedimentary indigenous microbial community may shift the composition and structure as well as function priority and interaction network to increase their adaptability and/or resistance to environmental contamination. PMID:26391875

  14. Sedimentary geology of the middle Carboniferous of the Donbas region (Dniepr-Donets basin, Ukraine)

    PubMed Central

    van Hinsbergen, Douwe J. J.; Abels, Hemmo A.; Bosch, Wolter; Boekhout, Flora; Kitchka, Alexander; Hamers, Maartje; van der Meer, Douwe G.; Geluk, Mark; Stephenson, Randell A.

    2015-01-01

    The Paleozoic Dniepr-Donets Basin in Belarus, Ukraine, and Russia forms a major hydrocarbon province. Although well- and seismic data have established a 20 km thick stratigraphy, field-studies of its sediments are scarce. The inverted Donbas segment (Ukraine) exposes the middle Carboniferous part of the basin's stratigraphy. Here, we provide detailed sedimentological data from 13 sections that cover 1.5 of the total of 5 km of the Bashkirian and Moscovian stages and assess the paleoenvironment and paleo-current directions. Middle Carboniferous deposition occurred in a shelf environment, with coal deposition, subordinate fluvial facies, and abundant lower and middle shoreface facies, comprising an intercalated package of potential source and reservoir rocks. Sedimentary facies indicate a paleodepth range from below storm wave base to near-coastal swamp environments. Sedimentation and subsidence were hence in pace, with subtle facies changes likely representing relative sea-level changes. Paleocurrent directions are remarkably consistently southeastward in time and space in the different sedimentary facies across the Donbas Fold Belt, illustrating a dominant sedimentary infill along the basin axis, with little basin margin influence. This suggests that the middle Carboniferous stratigraphy of the Dniepr-Donets basin to the northwest probably contains significant amounts of fluvial sandstones, important for assessing hydrocarbon reservoir potential. PMID:25791400

  15. Potential Cement Phases in Sedimentary Rocks Drilled by Curiosity at Gale Crater, Mars

    NASA Technical Reports Server (NTRS)

    Rampe, E. B.; Morris, R. V.; Bish, D. L.; Chipera, S. J.; Ming, D. W.; Blake, D. F.; Vaniman, D. T.; Bristow, T. F.; Cavanagh, P.; Farmer, J. D.; Morrison, S. M.; Siebach, K.; Treiman, A. H.; Achilles, C. N.; Blaney, D.; Crisp, J. A.; Des Marais, D. J.; Downs, R. T.; Fendrich, K.; Martin-Torres, J.; Morookian, J. M.; Zorzano, M.-P.; Sarrazin, P.; Spanovich, N.; Yen, A. S.

    2015-01-01

    The Mars Science Laboratory rover Curiosity has encountered a variety of sedimentary rocks in Gale crater with different grain sizes, diagenetic features, sedimentary structures, and varying degrees of resistance to erosion. Curiosity has drilled three rocks to date and has analyzed the mineralogy, chemical composition, and textures of the samples with the science payload. The drilled rocks are the Sheepbed mudstone at Yellowknife Bay on the plains of Gale crater (John Klein and Cumberland targets), the Dillinger sandstone at the Kimberley on the plains of Gale crater (Windjana target), and a sedimentary unit in the Pahrump Hills in the lowermost rocks at the base of Mt. Sharp (Confidence Hills target). CheMin is the Xray diffractometer on Curiosity, and its data are used to identify and determine the abundance of mineral phases. Secondary phases can tell us about aqueous alteration processes and, thus, can help to elucidate past aqueous environments. Here, we present the secondary mineralogy of the rocks drilled to date as seen by CheMin and discuss past aqueous environments in Gale crater, the potential cementing agents in each rock, and how amorphous materials may play a role in cementing the sediments.

  16. Pre-lithification tectonic foliation development in a clastic sedimentary sequence

    NASA Astrophysics Data System (ADS)

    Meere, Patrick; Mulchrone, Kieran; McCarthy, David; Timmermann, Martin; Dewey, John

    2016-04-01

    The current view regarding the timing of regionally developed penetrative tectonic fabrics in sedimentary rocks is that their development postdates lithification of those rocks. In this case fabric development is achieved by a number of deformation mechanisms including grain rigid body rotation, crystal-plastic deformation and pressure solution (wet diffusion). The latter is believed to be the primary mechanism responsible for shortening and the domainal structure of cleavage development commonly observed in low grade metamorphic rocks. In this study we combine field observations with strain analysis and modelling to fully characterise considerable (>50%) mid-Devonian Acadian crustal shortening in a Devonian clastic sedimentary sequence from south west Ireland. Despite these high levels of shortening and associated penetrative tectonic fabric there is a marked absence of the expected domainal cleavage structure and intra-clast deformation, which are expected with this level of deformation. In contrast to the expected deformation processes associated with conventional cleavage development, fabrics in these rocks are a product of translation, rigid body rotation and repacking of extra-formational clasts during deformation of an un-lithified clastic sedimentary sequence.

  17. A process-sedimentary framework for characterizing recent and ancient sabkhas

    USGS Publications Warehouse

    Handford, C.R.

    1981-01-01

    The discovery of sabkha environments during the 1960's, marked the beginning of Recent evaporite sedimentological studies and their perception as models for facies analysis. However, variation among Recent sabkhas, though recognized by the geologic community, has not been duly addressed, which has resulted in overuse of the Trucial Coast model in comparative sedimentological studies. Knowledge of the dominant physical processes which determine sabkha morphology, and of the sedimentary response to those processes, can lead to a fundamental understanding of a sabkha's origin and of how it differs from other sabkhas. Physical processes thought to be most important (besides evaporation) include those operative under: (1) marine-; (2) fluvial-lacustrine-; and (3) eolian-dominated conditions. Dominance of one or more of these in the proper settings give rise to marine coastal sabkhas, continental playas, and interdune sabkhas. Sedimentary responses to dominant physical processes lead to the development of sabkhas consisting of a combination of either: (1) terrigenous clastics; (2) carbonate-sulfate (anhydrite-gypsum) minerals; or (3) soluble salts (halite, sylvite, polyhalite, etc.). Sediment characterization can also allow discrimination of the range or compositional variety in, for example, coastal sabkhas. Where applied to the stratigraphic record, this classification system may help unravel the sedimentary history of an ancient sabkha system, and a determination of the dominant physical processes that ruled its development. ?? 1981.

  18. Miocene-Pliocene transition in the southern Cyprus basins: The sedimentary expression of regional tectonic events

    SciTech Connect

    Orzag-Sperber, F.; Rouchy, J.M. )

    1988-08-01

    In the southern part of Cyprus, a Maastrichtian-Pleistocene sedimentary area fringes Troodos Mountain, a fragment of an ancient crust. During the Neogene, three basins formed in this area: Polemi, Pissouri, and Psematismenos. A deep marine condition has prevailed since the Maastrichtian. During the Paleocene and early Miocene, the sea gradually become shallower until the Messinian, where the most spectacular sedimentary event concerns the deposition of evaporites contemporaneous with other Mediterranean evaporites. Some sedimentary phenomena express the tectonic instability during the upper Miocene. A well-known tectonic event affecting the east Mediterranean region generally referred to as the Miocene-Pliocene phase occurs at the Miocene-Pliocene limit. Recent sedimentological studies indicate this event is in fact complex. The Tortonian-lower Pliocene period is marked by a constraint involving an N20 distension in the Polemi and Pissouri basins and an N100 distension in the Psematismenos basin. Sedimentologic studies have demonstrated three tectonic pulsations during the Messinian prior to the Pliocene transgression. These are expressed by two episodes of seismic brecciation and a paleoemersion indicated by paleosols and detrital discharges. These phenomena suggest brief tectonic instability during the Messinian. Microtectonic studies reveal that the main change in tectonic constraint does not coincide with the Miocene-Pliocene contact but occurs at the top of the lower Pliocene.

  19. Sedimentary cover deformations in the equatorial Atlantic and their comparison with geophysical fields

    NASA Astrophysics Data System (ADS)

    Sokolov, S. Yu.

    2017-01-01

    The deformations of the sedimentary cover at near-latitudinal geotraverses west and east of the Mid-Atlantic Ridge in the equatorial part of ocean are compared with potential fields and variations of the V p/ V s attribute at a depth of 470 km. The features of sedimentary cover deformations in abyssal basins are formulated, as well as their differences from the undisturbed bedding of sediments. The elements of chain of phenomena with common spatial manifestations and cause-and-effect relationships have been established, including heterogeneous horizontal movements, which make up macrojointing above "cold" mantle blocks at a depth of 470 km; serpentinization of upper-mantle rocks; the formation of superposed magnetic anomalies; the release of the fluids, which acoustically bleach out the sedimentary sequence in seismic imaging; and decompaction of rocks leading to vertical motions and forced folding. The origin of the Atlantic marginal dislocation zone is explained. The coincidence of the deformation boundary in the equatorial Atlantic with the zero contour line of the V p/ V s attribute is revealed. This coincidence is an indicator of the rheological state of the upper mantle.

  20. Distinct Factors Shape Aquatic and Sedimentary Microbial Community Structures in the Lakes of Western China

    PubMed Central

    Yang, Jian; Jiang, Hongchen; Wu, Geng; Liu, Wen; Zhang, Guojing

    2016-01-01

    Little is known about the relative importance of spatial and environmental factors to structuring aquatic and sedimentary microbial biogeography in lakes. Here, we investigated the microbial community composition (MCC) of the water (n = 35) and sediment (n = 35) samples from 16 lakes in western China (salinity: freshwater to salt saturation; pairwise geographical distance: 9–2027 km) using high-throughput sequencing and evaluated the relative importance of spatial and environmental factors to microbial (including total, abundant, and rare) distributions. Our results showed that spatial factors were more important than environmental factors in shaping the biogeography of aquatic and sedimentary microbial communities in the studied lakes, and spatial factors on abundant microbial community was stronger than that on the total/rare microbial communities. Moreover, sedimentary rare MCC might be more sensitive to environmental factors than its aquatic counterpart. Such different biogeography responses of total, abundant, and rare communities to environmental and spatial factors could be ascribed to different physiochemical properties between water and sediment. Collectively, this study expands our understanding of factors shaping microbial biogeography of total, abundant, and rare communities between waters and sediments of lakes. PMID:27877171

  1. Evolution of major sedimentary mounds on Mars: Buildup via anticompensational stacking modulated by climate change

    NASA Astrophysics Data System (ADS)

    Kite, Edwin S.; Sneed, Jonathan; Mayer, David P.; Lewis, Kevin W.; Michaels, Timothy I.; Hore, Alicia; Rafkin, Scot C. R.

    2016-11-01

    We present a new database of >300 layer orientations from sedimentary mounds on Mars (Mount Sharp/Aeolis Mons, plus Nia, Juventae, Ophir, Ceti, Melas, Coprates, and Ganges Mensae). Together, these mounds make up ½ of the total volume of canyon/crater-hosted sedimentary mounds on Mars. The layer orientations, together with draped landslides, and draping of rocks over differentially eroded paleodomes, indicate that for the stratigraphically uppermost 1 km, the mounds formed by the accretion of draping strata in a mound shape. The layer-orientation data further suggest that layers lower down in the stratigraphy also formed by the accretion of draping strata in a mound shape. The data are consistent with terrain-influenced wind erosion but inconsistent with tilting by flexure, differential compaction over basement, or viscoelastic rebound. We use a simple model of landscape evolution to show how the erosion and deposition of mound strata can be modulated by shifts in obliquity. The model is driven by multi-Gyr calculations of Mars' chaotic obliquity and a parameterization of terrain-influenced wind erosion that is derived from mesoscale modeling. The model predicts that Mars mound stratigraphy emerges from a drape-and-scrape cycle. Our results suggest that mound-spanning unconformities with kilometers of relief emerge as the result of chaotic obliquity shifts. Our results support the interpretation that Mars' rocks record intermittent liquid-water runoff during a ≫ 108 yr interval of sedimentary rock emplacement.

  2. Late Mesozoic North African continental margin: Sedimentary sequences and subsidence history

    SciTech Connect

    Kuhnt, W.; Obert, D.

    1988-08-01

    Cretaceous facies types and subsidence history have been studied along two well outcropping and almost complete transversals through the Tellian units of the Mesozoic North African margin, the Western Rif (Morocco), and the Babors (Algeria). Sedimentologic observations and characteristic foraminiferal assemblages enabled estimates for Late Cretaceous paleobathymetries. Both palinspastic reconstruction and sedimentologic and biofacies analyses led to the following results. (1) The morphology and evolution of the Cretaceous North African margin, which in general represents a classic passive continental margin, were complicated by various factors such as Late Cretaceous compressional and lateral movements, the onset of (tectonically controlled ) diapirism, and the existence of intramarginal highs and basins. (2) The Cretaceous subsidence history of both areas can be divided into four stages which are accompanied by characteristic sedimentary formations: (I) distension and subsidence of the margin (Early Cretaceous); (II) a first compressional phase with uplift and slight metamorphism in the Albian/early Cenomanian which affected mainly the northerly paleogeographic zones, accompanied by first diapiric movements and resedimentation of Triassic saliferous material; (III) a Late Cretaceous stage of subsidence (Cenomanian-Santonian); and (IV) a second compressional phase starting with the Campanian and reflected by the formation of sedimentary klippes and olistostromes. (3) As a general trend, sedimentary basins deepened from south to north during Campanian/Maastrichtian time, giving rise to a characteristic succession of bathymetric zones which have been observed on both transversals.

  3. Sea-floor morphology and sedimentary environments in southern Narragansett Bay, Rhode Island

    USGS Publications Warehouse

    McMullen, Katherine Y.; Poppe, Lawrence J.; Blackwood, Dann S.; Nardi, Matthew J.; Andring, Matthew A.

    2015-09-09

    Multibeam echosounder data collected by the National Oceanic and Atmospheric Administration along with sediment samples and still and video photography of the sea floor collected by the U.S. Geological Survey were used to interpret sea-floor features and sedimentary environments in southern Narragansett Bay, Rhode Island, as part of a long-term effort to map the sea floor along the northeastern coast of the United States. Sea-floor features include rocky areas and scour depressions in high-energy environments characterized by erosion or nondeposition, and sand waves and megaripples in environments characterized by coarse-grained bedload transport. Two shipwrecks are also located in the study area. Much of the sea floor is relatively featureless within the resolution of the multibeam data; sedimentary environments in these areas are characterized by processes associated with sorting and reworking. This report releases bathymetric data from the multibeam echosounder, grain-size analyses of sediment samples, and photographs of the sea floor and interpretations of the sea-floor features and sedimentary environments. It provides base maps that can be used for resource management and studies of topics such as benthic ecology, contaminant inventories, and sediment transport.

  4. Sedimentary geology of the middle Carboniferous of the Donbas region (Dniepr-Donets basin, Ukraine)

    NASA Astrophysics Data System (ADS)

    van Hinsbergen, Douwe J. J.; Abels, Hemmo A.; Bosch, Wolter; Boekhout, Flora; Kitchka, Alexander; Hamers, Maartje; van der Meer, Douwe G.; Geluk, Mark; Stephenson, Randell A.

    2015-03-01

    The Paleozoic Dniepr-Donets Basin in Belarus, Ukraine, and Russia forms a major hydrocarbon province. Although well- and seismic data have established a 20 km thick stratigraphy, field-studies of its sediments are scarce. The inverted Donbas segment (Ukraine) exposes the middle Carboniferous part of the basin's stratigraphy. Here, we provide detailed sedimentological data from 13 sections that cover 1.5 of the total of 5 km of the Bashkirian and Moscovian stages and assess the paleoenvironment and paleo-current directions. Middle Carboniferous deposition occurred in a shelf environment, with coal deposition, subordinate fluvial facies, and abundant lower and middle shoreface facies, comprising an intercalated package of potential source and reservoir rocks. Sedimentary facies indicate a paleodepth range from below storm wave base to near-coastal swamp environments. Sedimentation and subsidence were hence in pace, with subtle facies changes likely representing relative sea-level changes. Paleocurrent directions are remarkably consistently southeastward in time and space in the different sedimentary facies across the Donbas Fold Belt, illustrating a dominant sedimentary infill along the basin axis, with little basin margin influence. This suggests that the middle Carboniferous stratigraphy of the Dniepr-Donets basin to the northwest probably contains significant amounts of fluvial sandstones, important for assessing hydrocarbon reservoir potential.

  5. Dechlorinating microorganisms in a sedimentary rock matrix contaminated with a mixture of VOCs.

    PubMed

    Lima, Gláucia; Parker, Beth; Meyer, Jessica

    2012-06-05

    Microbiological characterizations of contaminant biodegradation in fractured sedimentary rock have primarily focused on the biomass suspended in groundwater samples and disregarded the biomass attached to fractures and in matrix pores. In fractured sedimentary rock, diffusion causes nearly all contaminant mass to reside in porous, low-permeability matrix. Microorganisms capable of contaminant degradation can grow in the matrix pores if the pores and pore throats are sufficiently large. In this study, the presence of dechlorinating microorganisms in rock matrices was investigated at a site where a fractured, flat-lying, sandstone-dolostone sequence has been contaminated with a mixture of chlorinated and aromatic hydrocarbons for over 40 years. The profile of organic contaminants as well as the distribution and characterization of the microbial community spatial variability was obtained through depth-discrete, high-frequency sampling along a 98-m continuous rock core. Dechlorinating microorganisms, such as Dehalococcoides and Dehalobacter, were detected in the rock matrices away from fracture surfaces, indicating that biodegradation within the rock matrix blocks should be considered as an important component of the system when evaluating the potential for natural attenuation or remediation at similar sedimentary rock sites.

  6. Estimate of Geothermal Energy Resource in Major U.S. Sedimentary Basins (Presentation)

    SciTech Connect

    Porro, C.; Augustine, C.

    2012-04-01

    This study estimates the magnitude of geothermal energy from fifteen major known US sedimentary basins and ranks these basins relative to their potential. Because most sedimentary basins have been explored for oil and gas, well logs, temperatures at depth, and reservoir properties are known. This reduces exploration risk and allows development of geologic exploration models for each basin as well as a relative assessment of geologic risk elements for each play. The total available thermal resource for each basin was estimated using the volumetric heat-in-place method originally proposed by Muffler (USGS). Total sedimentary thickness maps, stratigraphic columns, cross sections, and temperature gradient Information were gathered for each basin from published articles, USGS reports, and state geological survey reports. When published data was insufficient, thermal gradients and reservoir properties were derived from oil and gas well logs obtained on oil and gas commission websites. Basin stratigraphy, structural history, and groundwater circulation patterns were studied in order to develop a model that estimates resource size and temperature distribution, and to qualitatively assess reservoir productivity.

  7. Organic matter accumulation in a thick, lacustrine, Lower Cretaceous sedimentary sequence in Gabon: Facies and maturity variations

    SciTech Connect

    Ralf, L.; Wilkes, H.

    1995-08-01

    A total of about forty core samples representing an almost two kilometer thick, lacustrine sedimentary sequence of Neocomian age in the south Gabon basin was analysed for its hydrocarbon generation potential, maturity and further organic matter characteristics. Organic carbon concentrations are variable and not particularly high (0.4-5%), but the organic matter is hydrogen-rich. This hydrogen-richness finds its expression in high hydrogen indices (about 600 to 700 mg hc/g TOC) which decrease with increasing maturation. According to pyrolysis experiments, hydrocarbon generation from the immature sediments is predicted to begin only at temperatures greater than 100{degrees}C and reaches a maximum only at temperatures greater than 150{degrees}C, because the organic material possesses a very high thermal stability. Such a high thermal stability was already established for lacustrine organic matter from some other deposits (e.g. Green River oil shales) and is certainly an important factor for the evaluation of hydrocarbon potentials in lacustrine basins. The maturity of the organic matter changes from immature to mature with increasing depth. Peak oil generation stage was almost reached by the deepest samples as indicated by a variety of optical and geochemical parameters. Generated petroleum should be wax-rich and rather poor in gas, except if oil to gas cracking occurs within the source rocks. With respect to molecular geochemistry, several interesting pecularities were found. As an example, variable distributions of several unknown tetracyclic terpanes (molecular formula C{sub 24}H{sub 42}) were detected in the samples of lower maturity. Two series of terpane pseudohomologues occur in the more mature samples, one of which is assumed to consist of diahopanes, the other yet remaining unknown. These compounds seem to be widely distributed in lacustrine sediments of higher maturity, thus possibly representing maturity and/or facies indicators.

  8. The Surtsey Magma Series

    PubMed Central

    Ian Schipper, C.; Jakobsson, Sveinn P.; White, James D.L.; Michael Palin, J.; Bush-Marcinowski, Tim

    2015-01-01

    The volcanic island of Surtsey (Vestmannaeyjar, Iceland) is the product of a 3.5-year-long eruption that began in November 1963. Observations of magma-water interaction during pyroclastic episodes made Surtsey the type example of shallow-to-emergent phreatomagmatic eruptions. Here, in part to mark the 50th anniversary of this canonical eruption, we present previously unpublished major-element whole-rock compositions, and new major and trace-element compositions of sideromelane glasses in tephra collected by observers and retrieved from the 1979 drill core. Compositions became progressively more primitive as the eruption progressed, with abrupt changes corresponding to shifts between the eruption’s four edifices. Trace-element ratios indicate that the chemical variation is best explained by mixing of different proportions of depleted ridge-like basalt, with ponded, enriched alkalic basalt similar to that of Iceland’s Eastern Volcanic Zone; however, the systematic offset of Surtsey compositions to lower Nb/Zr than other Vestmannaeyjar lavas indicates that these mixing end members are as-yet poorly contained by compositions in the literature. As the southwestern-most volcano in the Vestmannaeyjar, the geochemistry of the Surtsey Magma Series exemplifies processes occurring within ephemeral magma bodies on the extreme leading edge of a propagating off-axis rift in the vicinity of the Iceland plume. PMID:26112644

  9. Series of JASMINE missions

    NASA Astrophysics Data System (ADS)

    Gouda, N.

    2011-02-01

    We are planning three space astrometry missions as a series of JASMINE missions; Nano-JASMINE, Small-JASMINE and (Medium-sized)JASMINE. JASMINE is an abbreviation of Japan Astrometry Satellite Mission of INfrared Exploration. The JASMINE mission will measure in an infrared band annual parallaxes, positions on the celestial sphere, and proper motions of many stars in the bulge of the Milky Way (the Galaxy) with high accuracies. A target launch date is the first half of the 2020s. Before the launch of JASMINE, we are planning Nano-JASMINE and Small-JASMINE. Nano-JASMINE uses a very small nano-satellite and it is determined to be launched in 2011. Small-JASMINE is a downsized version of the JASMINE satellite, which observes toward restricted small regions of the Galactic bulge. A target launch date is around 2016. A completely new "map" of the Galactic bulge given by Small-JASMINE and JASMINE will bring us many exciting scientific results.

  10. Sedimentary regime of deep submarine canyons around Fylla Banke, northeastern Labrador Sea

    NASA Astrophysics Data System (ADS)

    Paulsen, Dorthe; Kuijpers, Antoon; Seidenkrantz, Marit-Solveig; Nielsen, Tove

    2014-05-01

    Sedimentary regime of deep submarine canyons around the Fylla Banke, northeastern Labrador Sea Dorthe Paulsen (1), Antoon Kuijpers (2), Marit-Solveig Seidenkrantz (3) and Tove Nielsen (2) 1) Department of Geosciences and Natural Resource Management, University of Copenhagen, Øster Voldgade 10, DK-1350 Copenhagen K 2) Geological Survey of Denmark and Greenland (GEUS), Øster Voldgde 10, DK-1350 Copenhagen K. 3) Centre for Past Climate Studies, Department of Geoscience, Aarhus University. Hoegh-Guldbergs Gade 2, DK-8000 Aarhus C The southern end of the Davis Strait, the comparatively shallow-water area separating the Labrador Sea from the Baffin Bay, is cut by two deep submarine canyons of west Greenland, on the western and eastern side of the Fylla Banke, respectively. The purpose of this study is to investigate Late Pleistocene sedimentary processes governing the area of the two canyons in order to test if gravity flows or ocean currents are the most important factors governing canyon sedimentary processes in this region. Furthermore, an account is given on the formation of the two canyons in order to explain the significant difference between them. The study was carried out based on seismic profiles combined with bathymetric information, and a single sidescan sonar profile from one of the canyons (western canyon). Sedimentary information and an age model are derived from of a 5-m long gravity core (TTR13-AT-479G) collected from the mouth of the western canyon (southern end). The data indicates that the sedimentary regime is today highly affected by northward transport of the ocean currents and that gravity flows (southward from shallower to deep waters) are only of limited significance today. The deep southern end of the canyons are influenced by the upper parts of the deep North Atlantic Deep Water, but the majority of the sediment transport is linked to the strong northward flow of the lower parts of the West Greenland Current. For comparison the sediment

  11. In-situ Micro-structural Studies of Gas Hydrate Formation in Sedimentary Matrices

    NASA Astrophysics Data System (ADS)

    Kuhs, Werner F.; Chaouachi, Marwen; Falenty, Andrzej; Sell, Kathleen; Schwarz, Jens-Oliver; Wolf, Martin; Enzmann, Frieder; Kersten, Michael; Haberthür, David

    2015-04-01

    The formation process of gas hydrates in sedimentary matrices is of crucial importance for the physical and transport properties of the resulting aggregates. This process has never been observed in-situ with sub-micron resolution. Here, we report on synchrotron-based micro-tomographic studies by which the nucleation and growth processes of gas hydrate were observed in different sedimentary matrices (natural quartz, glass beds with different surface properties, with and without admixtures of kaolinite and montmorillonite) at varying water saturation. The nucleation sites can be easily identified and the growth pattern is clearly established. In under-saturated sediments the nucleation starts at the water-gas interface and proceeds from there to form predominantly isometric single crystals of 10-20μm size. Using a newly developed synchrotron-based method we have determined the crystallite size distributions (CSD) of the gas hydrate in the sedimentary matrix confirming in a quantitative and statistically relevant manner the impressions from the tomographic reconstructions. It is noteworthy that the CSDs from synthetic hydrates are distinctly smaller than those of natural gas hydrates [1], which suggest that coarsening processes take place in the sedimentary matrix after the initial hydrate formation. Understanding the processes of formation and coarsening may eventually permit the determination of the age of gas hydrates in sedimentary matrices [2], which are largely unknown at present. Furthermore, the full micro-structural picture and its evolution will enable quantitative digital rock physics modeling to reveal poroelastic properties and in this way to support the exploration and exploitation of gas hydrate resources in the future. [1] Klapp S.A., Hemes S., Klein H., Bohrmann G., McDonald I., Kuhs W.F. Grain size measurements of natural gas hydrates. Marine Geology 2010; 274(1-4):85-94. [2] Klapp S.A., Klein H, Kuhs W.F. First determination of gas hydrate

  12. Use of structural geology in exploration for and mining of sedimentary rock-hosted Au deposits

    USGS Publications Warehouse

    Peters, Stephen G.

    2001-01-01

    Structural geology is an important component in regional-, district- and orebody-scale exploration and development of sedimentary rock-hosted Au deposits.Identification of timing of important structural events in an ore district allows analysis and classification of fluid conduits and construction of genetic models for ore formation.The most practical uses of structural geology deal with measurement and definition of various elements that comprise orebodies, which can then be directly applied to ore-reserve estimation,ground control,grade control, safety issues,and mine planning.District- and regional-scale structural studies are directly applicable to long-term strategic planning,economic analysis,and land ownership. Orebodies in sedimentary rock-hosted Au deposits are discrete, hypogene, epigenetic masses usually hosted in a fault zone,breccia mass, or lithologic bed or unit. These attributes allow structural geology to be directly applied to the mining and exploration of sedimentary rock-hosted Au deposits. Internal constituents in orebodies reflect unique episodes relating to ore formation.The main internal constituents in orebodies are ore minerals, gangue, and alteration minerals that usually are mixed with one another in complex patterns, the relations among which may be used to interpret the processes of orebody formation and control.Controls of orebody location and shape usually are due to structural dilatant zones caused by changes in attitude, splays, lithologic contacts,and intersections of the host conduit or unit.In addition,conceptual parameters such as district fabric,predictable distances, and stacking also are used to understand the geometry of orebodies.Controls in ore districts and location and geometry of orebodies in ore districts can be predicted to various degrees by using a number of qualitative concepts such as internal and external orebody plunges,district plunge, district stacking, conduit classification, geochemical, geobarometric and

  13. Landform assemblages and sedimentary processes along the Norwegian Channel Ice Stream

    NASA Astrophysics Data System (ADS)

    Ottesen, Dag; Stokes, Chris R.; Bøe, Reidulv; Rise, Leif; Longva, Oddvar; Thorsnes, Terje; Olesen, Odleiv; Bugge, Tom; Lepland, Aave; Hestvik, Ole B.

    2016-06-01

    Several regional and detailed bathymetric datasets together with 2D and 3D seismic data are compiled to investigate the landform assemblages and sedimentary processes along the former path of the Norwegian Channel Ice Stream (NCIS). At the broad scale, the glacial geomorphology and sedimentary architecture reveals three different zones along the ice-stream path, characterized by: (1) glacial erosion in the onset zone and inner shelf area, (2) sediment transport through the main trunk of the ice stream across the mid-shelf, and (3) a zone of deposition towards the outer continental shelf edge. Along the first 400 km of the ice stream bed (outer Oslofjord-Skagerrak-Stavanger) a major overdeepening is associated with suites of crag-and-tail features at the transition from the crystalline bedrock to the sedimentary bedrock, together with evidence of glaciotectonic thrusting in the form of hill-hole pairs. Here we interpret extensive erosion of both sedimentary rocks and Quaternary sediments. This zone is succeeded by an approximately 400 km long zone, through which most of the sediments eroded from the inner shelf were transported, rather than being deposited. We infer that sediment was transported subglacially and is likely to have been advected downstream by soft sediment deformation. The thickness of till of inferred Weichselian age generally varies from 0 and 50 m and this zone is characterized by mega-scale glacial lineations (MSGLs) which we interpret to be formed in a dynamic sedimentary system dominated by high sediment fluxes, but with some localized sediment accretion associated with lineations. Towards the shelf break, the North Sea Fan extends to the deep Norwegian Sea, and reflects massive sedimentation of glacigenic debris onto the continental slope. Numerous glacigenic debris flows accumulated and constructed a unit up to 400 m thick during the Last Glacial Maximum. The presence of these three zones (erosion, transport, deposition) is consistent with

  14. Geodynamical and Geochemical Features of Oil Generation in Sedimentary Basin of Volga-Ural Region

    NASA Astrophysics Data System (ADS)

    Plotnikova, I.

    2009-04-01

    Oil and gas prospects of Paleozoic sedimentary rocks of Volga-Ural Anticline (VUA) various researchers evaluate in different ways. More than 150 oil fields in Paleozoic formations were discovered in the eastern half of Republic of Tatarstan of the East European Platform. There were not found any significant fields in the western areas of investigation region. According to many investigators, the western part of the Tatarstan has unfavourable geological structure from oil and gas potential view. Solution of problem concerning revealing HC source for the fields of Volga-Ural oil and gas province certainly would alow to discuss about further prospects of this territory. Data available evidence that during Paleozoic time, an area of the present-day South-Tatarian Arch (STA) and North-Tatarian Arch was a passive continental margin along which a sediments rocks up to 2 km thick was accumulated. Generation potential of organic matter containing in increased concentrations in domanikoid deposits was obtained. It has been discovered that the cumulative production in some oil areas of the Romashkino oil field substantially exceeds formerly proven, recoverable, reserves. Moreover, the volume of oil produced has already significantly exceeded the amount of oil that the Domanik strata could have generated as supposed source rocks of the South Tatarstan arch and the adjacent areas. Cumulative oil production in Tatarstan has already reached 3.0B tons, thus substantially exceeding 709M tons, calculated geochemically on the basis of the Paleozoic source rock potentials of all sedimentary strata. This discrepancy obviously shows the impossibility for the commercial amounts of hydrocarbons of being generated from the available material of the sedimentary cover. Some experts explain this phenomenon by the errors made in the reserve estimates. But another consider this as the inflow or replenishment by the hydrocarbon flow from the crystalline basement along the faults. Who is right

  15. Evidence for a sedimentary fingerprint of an asymmetric flow field surrounding a short seamount

    NASA Astrophysics Data System (ADS)

    Turnewitsch, Robert; Reyss, Jean-Louis; Chapman, David C.; Thomson, John; Lampitt, Richard S.

    2004-06-01

    Physical oceanographic modeling and field studies have shown that kilometer-scale seafloor elevations of comparable breadth and width (abyssal hills, knolls, seamounts) are surrounded by complex flow fields. Asymmetric flow fields, reversed flow and closed streamlines around the topographic feature (Taylor caps), and resonantly amplified tidal currents around the seamount rim potentially control near-bottom particle dynamics, particle deposition at the seafloor and, consequently, the formation of the sedimentary record. We combine numerical modeling and field data to study how such topographically controlled flow-field features are reflected in the sedimentary record. Sediment deposition on a topographically isolated abyssal knoll (height: 900 m) on the Porcupine Abyssal Plain in the Northeast Atlantic (water depth above the abyssal plain: 4850 m) was studied, (1) by comparing the spatial distribution of 210Pb fluxes, calculated from inventories of sedimentary excess 210Pb, with 210Pb input from the water column as recorded by sediment traps; and (2) by comparing sedimentary grain-size distributions and Zr/Al ratios (an indicator for contents of the heavy mineral zircon) at slope, summit and far-field sites. Given Rossby numbers ≥0.23, a fractional seamount height of ˜0.2, and the absence of diurnal tides it is concluded that an asymmetric flow field without Taylor cap and without amplified tidal currents around the seamount rim is the principal flow-field feature at this knoll. The results and conclusions are as follows: (1) Geochemical and grain-size patterns in the sedimentary record largely agree with the predicted pattern of flow intensity around the topographic elevation: with increasing current strength (erosiveness) there is evidence for a growing discrepancy between water column-derived and sediment-derived 210Pb fluxes, and for increasing contents of larger and heavier particles. The topographically controlled flow field distorts a homogeneous particle

  16. Alteration mineralogy and geochemistry as an exploration tool for detecting basement heat sources in sedimentary basins

    NASA Astrophysics Data System (ADS)

    Uysal, Tonguc; Gasparon, Massimo; van Zyl, Jacobus; Wyborn, Doone

    2010-05-01

    The Cooper Basin located in South Australia and Queensland hosts some of the hottest granites in the world at economic drilling depths (240°C at 3.5 km). Investigating the mechanism of heat-producing element enrichment in the Cooper Basin granite is crucial for understanding hot-dry rock geothermal systems and developing exploration strategies. Trace element (by ICP-MS) and stable isotope geochemistry of whole rock granite samples and hydrothermal phyllosilicate alteration minerals separated from the granite and overlying sandstones and mudstones of the Cooper Basin were examined in detail. Granite core samples from relatively shallow depths in Moomba 1 and Big Lake 1 are strongly altered with pervasive sericite (illite) and quartz precipitation, probably associated with intense micro-fracturing and veining. The intensity of hydrothermal alteration is less in deeper samples from Mcleod 1, Jolokia and Habanero 1. Highly altered granites from former holes are substantially enriched in lithophile elements, particularly in Cs, Rb, Be, Th, U and rare earth elements (REE) relative to the upper continental crust (UCC). U and Th contents with concentrations of up to 30 and 144 ppm, respectively, are 10 and 13 times higher than those of the UCC. Comparison of the trace element composition of the same samples dissolved by open beaker acid digestion and high-pressure acid bomb digestion (to dissolve zircon) shows that zircon is not the main repository of U and Th in the Cooper Basin granite. Instead, we propose that the enrichment of heat-producing elements was promoted by a regional hydrothermal event leading to the precipitation of U and Th- bearing minerals such as illite, K-feldspar and thorite. Crystallinity index (illite crystallinity) of the sericite indicates hydrothermal temperatures ranging from 250°C (in Moomba 1 and Big Lake 1) to 350°C (in McLeod 1 and Jolokia 1). In the overlying sedimentary rocks, crystallinity of authigenic illites translates to lower

  17. Sedimentary Snow.

    ERIC Educational Resources Information Center

    Green, Douglas W.; Lowenstein, Tim

    1994-01-01

    Describes activities that take advantage of heavy snowfalls to study numerous geological concepts including sedimentation, precipitation, morphology and metamorphosis of crystals, compaction and cementation, fossilization, and erosion. (JRH)

  18. Timing the last interglacial-glacial transition in glacial sedimentary sequences of the Hudson Bay lowlands (Canada)

    NASA Astrophysics Data System (ADS)

    Roy, M.; Allard, G.; Ghaleb, B.; Lamothe, M.

    2010-12-01

    Paleoclimate records (oxygen isotopes and speleothems) indicate that the onset of the last glacial cycle was characterized by rapid and large-scale growth of continental ice sheets. The timing of the inception of the Laurentide ice sheet (LIS) and its subsequent evolution (extent) remain, however, largely unconstrained. The depositional record of the Hudson Bay Lowlands (HBL) is of particular interest to these issues because this region is located near the former geographic center of the LIS. The presence of nonglacial deposits in HBL glacial sedimentary sequences thus implies drastic changes in ice sheet configuration, but constraining these ice volume changes through absolute dating of nonglacial sediments has been so far inconclusive. Here we use radiocarbon, U-series, and optical stimulated luminescence (OSL) methods to constrain the age of an extensive nonglacial unit containing abundant wood fragments enclosed in compacted clay lying below several meters of glacial deposits along the Nottaway River, in the southeastern sector of the HBL. This region is particularly interesting because it lies near one of the inception centers of the LIS. Radiocarbon dating of a wood fragment yielded a nonfinite 14C age of >55.2 ka, in agreement with similar dating attempts throughout the HBL. Measurements of U and Th concentrations and isotope ratios on fossil wood samples revealed consistent 230Th/U ages, indicating that the wood fragments were subject to a single episode of uranium uptake, with apparently no subsequent disturbance of the geochemical system. Despite mechanical cleaning of the wood outer surfaces, non-authigenic 230Th was found in most samples and correction for this detrital contamination yielded an isochron age of 106.8 (+12.3, -10.3) ka, which represents a minimum age for this unit. The 230Th/U age constraint is nonetheless supported by a series of OSL ages obtained for the overlying fluvial sands, thereby assigning the Nottaway nonglacial unit to the end

  19. From source-to-sink: The Late Permian SW Gondwana paleogeography and sedimentary dispersion unraveled by a multi-proxy analysis

    NASA Astrophysics Data System (ADS)

    Alessandretti, Luciano; Machado, Rômulo; Warren, Lucas Veríssimo; Assine, Mario Luis; Lana, Cristiano

    2016-10-01

    The Late Permian sedimentary succession of the Paraná Basin, southern Brazil, provide a valuable source of information about sediment provenance, tectonic processes and, consequently, the paleogeography of the southwestern Gondwana supercontinent. In order to understand the patterns of sedimentary dispersal and reconstruct the Late Permian source-to-sink dynamic, we report a complete series of U-Pb ages and Hf isotopic compositions of detrital zircons from the Rio do Rasto Formation sandstones allied with detailed paleocurrent and sedimentologic data. Our integrated provenance study reveals a consistent sediment transport from the south to the north and northwest. According to the evaluation of zircon ages and Hf isotopes, it was possible to determine four distinct source areas: (i) a distant Late Paleozoic active magmatic arc located in the southwestern Gondwana margin (i.e. Gondwanides Orogen), corresponding to the North Patagonian Massif; (ii) recycling of orthoquartzites from the uplifted Paleozoic Ventania Fold Belt and immature sandstones from the Claromecó Foreland Basin in central-eastern Argentina and the Silurian-Devonian successions of the southern Paraná Basin (central-northern Uruguay) and North Patagonian Massif; (iii) exhumed areas of the Archean-Paleoproterozoic basement and Neoproterozoic to Early Paleozoic mobile belts of the Damara in southwestern Africa and Ribeira Fold Belt in Uruguay and southern Brazil; and (iv) southeastward provenance of Grenvillian (1.2-1.0 Ga) zircons coming from the mafic to intermediate Mesoproterozoic igneous units of the Namaqua-Natal Belt in South Africa and Namibia. These data allow us to argue that sediments deposited in the Paraná Basin during the Late Permian come from both short- and long-distance source areas. In this context, an important population of Permian detrital zircons comes from the Gondwanides Orogen in the south, probably carried by transcontinental alluvial systems. Close to the source area

  20. Digestive selection underlies differential utilization of phytoplankton and sedimentary organics by infaunal bivalves: Experiments with cockles (Cerastoderma edule) using cross-labelled mixed diets.

    PubMed

    Navarro, Enrique; Méndez, Soco; Urrutia, Miren Begoñe; Arambalza, Udane; Ibarrola, Irrintzi

    2016-09-01

    Differential utilization of phytoplankton and detrital particles present in natural sediments of mud-flats was studied in a series of experiments performed on the infaunal bivalve Cerastoderma edule. In order to assess digestive selection, parameters of food processing (organic ingestion rate: OIR, gross absorption efficiency: GAE and gut passage time: GPT) were recorded for each organic component in different combinations of food particles radio-labelled with (14)C. Experimental design included the use of both labelled diets of a sole organic component and cross-labelled diets; i.e., mixed suspensions presenting alternatively labelled one of the various components tested: phytoplankton cells, sedimentary organic particles and particulate detritus from vascular salt-marsh plants. Preferential absorption of phytoplankton was accounted for by absorption efficiency values that were two-fold those for sedimentary detritus when recorded with mixed diets of both organic components. Two factors contributed to this difference: a) higher digestibility of microalgae, measured as the ratio of GAE to GPT, and b) faster gut passage of detrital particles that results from digestive selection likely involving the preferential incorporation of phytoplankton into the digestive gland. However, when diets based on a sole organic component (either phytoplankton or detritus) were compared, larger GPT were recorded for detrital particles that enabled improving GAE of this rather refractory food. Overall results of these experiments are consistent with most studies in trophic ecology based on stable isotopes enrichment, concerning both the diversity of trophic sources used by marine bivalves and its preferential utilization of phytoplankton over phyto-detritus.

  1. An assessment of geochemical preparation methods prior to organic carbon concentration and carbon isotope ratio analyses of fine-grained sedimentary rocks

    NASA Astrophysics Data System (ADS)

    KöNitzer, Sven F.; Leng, Melanie J.; Davies, Sarah J.; Stephenson, Michael H.

    2012-09-01

    This study summarizes organic carbon isotope (δ13C) and total organic carbon (TOC) data from a series of tests undertaken to provide an appropriate methodology for pre-analysis treatment of mudstones from an Upper Carboniferous sedimentary succession, in order to develop a consistent preparation procedure. The main treatments involved removing both inorganic carbonate and hydrocarbons (which might be extraneous) before δ13C and TOC analysis. The results show that decarbonating using hydrochloric acid causes significant reduction in δ13C and total carbon (TC) of the bulk material due to the removal of inorganic carbonate. These changes are most pronounced where soluble calcium carbonate (rather than Ca-Mg-Fe carbonate) is present. Deoiled samples show only slightly higher mean δ13C where visible bitumen was extracted from the bulk sample. Moreover, the isotopic signatures of the extracts are closely correlated to those of their respective bulk samples, suggesting that small yields of hydrocarbons were generated in situ with no isotopic fractionation. In addition, further δ13C and TC analyses were performed on samples where mixing of oil-based drilling mud with brecciated core material had been undertaken. Brecciated mudstone material did not display distinct isotopic signals compared to the surrounding fine-grained material. Overall we show that the most accurate assessment of bulk organic carbon isotopes and concentration in these samples can be achieved through decarbonating the material prior to measurement via the `rinse method'. However, our results support recent findings that pre-analysis acid treatments can cause variable and unpredictable errors in δ13C and TOC values. We believe that, despite these uncertainties, the findings presented here can be applied to paleoenvironmental studies on organic matter contained within sedimentary rocks over a range of geological ages and compositions.

  2. Generalized series of Bessel functions

    NASA Astrophysics Data System (ADS)

    Al-Jarrah, A.; Dempsey, K. M.; Glasser, M. L.

    2002-06-01

    Known series of Bessel functions, currently available in handbooks, and many of Neumann type, are generalized to arbitrary order. The underlying result is a Poisson formula due to Titchmarsh. This formula gives rise to a Neumann series involving modified Bessel functions of integral order. The latter is the basis of many of the generalized series that follow. Included are examples of generalized trigonometric identities. The paper concludes by indicating the wide range of results that can be obtained.

  3. Permutations and time series analysis.

    PubMed

    Cánovas, Jose S; Guillamón, Antonio

    2009-12-01

    The main aim of this paper is to show how the use of permutations can be useful in the study of time series analysis. In particular, we introduce a test for checking the independence of a time series which is based on the number of admissible permutations on it. The main improvement in our tests is that we are able to give a theoretical distribution for independent time series.

  4. FROG: Time-series analysis

    NASA Astrophysics Data System (ADS)

    Allan, Alasdair

    2014-06-01

    FROG performs time series analysis and display. It provides a simple user interface for astronomers wanting to do time-domain astrophysics but still offers the powerful features found in packages such as PERIOD (ascl:1406.005). FROG includes a number of tools for manipulation of time series. Among other things, the user can combine individual time series, detrend series (multiple methods) and perform basic arithmetic functions. The data can also be exported directly into the TOPCAT (ascl:1101.010) application for further manipulation if needed.

  5. A model-based evaluation of sedimentary reconstructions of 10Be production rates

    NASA Astrophysics Data System (ADS)

    Carney, Lewis; Plancherel, Yves; Khatiwala, Samar; Henderson, Gideon

    2016-04-01

    Atmospheric production of 10Be is small when solar activity and, therefore, solar magnetic field and total solar irradiance are strong. Variations in solar activity affect climate and the production of other climate-relevant isotopes, such as 14C. Solar activity is thus an important variable to constrain. Since 10Be production is clearly related to solar activity and the cycle of beryllium is simpler than that of carbon, 10Be records in ice cores have been used to reconstruct total solar irradiance variability. Unfortunately, 10Be records in ice cores are not only affected by variations in atmospheric production, but are also modulated by changes in wind patterns since spatiotemporal atmospheric 10Be gradients are quite large. In that context, sedimentary 10Be records from the abyssal ocean could be of great interest: since the residence time of 10Be in the ocean is thought to be comparable to the overturning time-scale of the ocean, spatial 10Be gradients may be relatively weaker than those in the atmosphere. Under these conditions, regional oceanic variability should only weakly affect the distribution of 10Be in the ocean and local sedimentary 10Be records are expected to represent the global average 10Be production better than 10Be measured in ice cores. We here show results from a global ocean model of 10Be that we use to investigate the spatial variability of simulated sedimentary 10Be records and test the sensitivity of the 10Be sedimentary flux to uncertainties in the circulation field and in the particle chemistry of beryllium. Our ocean model is based on the Transport Matrix method. The surface 10Be input fluxes are taken from atmospheric model simulations. Our model experiments, constrained by available dissolved 10Be data, show that there exist regions in the ocean where the sedimentary 10Be flux is relatively insensitive to changes in input patterns and magnitudes, assumed particle chemistry and flux patterns, and ocean circulation. We submit that

  6. Shelf-edge sedimentary systems off Rio de Janeiro State, northern Santos basin-Brazil

    NASA Astrophysics Data System (ADS)

    Maia, R. M. C.; Dos Reis, A. T.; Gorini, C.; Silva, C. G.; Rabineau, M.; Granjeon, D.

    2012-04-01

    The sedimentary record of the continental shelf off Rio de Janeiro State is related to the opening and evolution of Atlantic Ocean. The combined analysis of high resolution seismic acquired in the early 80's (Geomar cruises) and 2D seismic lines of petroleum industry, coupled with chronostratigraphic data from oil industry's exploratory wells, allowed us to observe two different orders of sequences: of 3-4th order, that represents sedimentary units related of the Milankovitch cycles (100/40/20ky), and of 2nd order (10-100my). High resolution seismic allowed us to outline a first architectural framework for the actual shelf that is composed of stacked seismic units making up the major seismic sequences bounded by angular unconformities. According to the intern and extern configuration of their clinoforms, the seismic sequences were grouped into two distinctive stratigraphic sets, identified as Set I (Pliocene) and Set II (Upper Quaternary). Some architectural components of note include: (1) the characteristic upbuilt-outbuilt geometry of sequences that compose Set I (SqA, SqB and SqC), indicating that deposition has probably been favoured by a combination of prevailing subsidence regime (upbuilt pattern) accompanied by forced regressive deposits (outbuilt pattern); (2) the majority of sequences that make up Set II outbuilts as a composite seaward-thickening progradational wedge formed under dominant forced regression conditions, implying that the generation of accommodation space was less important than during the build-up of Set I. However, these sequences consistently pinch out in a progressively landward direction, suggesting a prevailing and increasing subsidence regime able to induce the progressive seaward tilting of the margin during the middle-late Pleistocene, and the subsequent partial preservation of regressive sequences of about 100-200 m thick at the level of the present-day mid-shelf, that prograded seaward for circa 15-25 km. These architectural

  7. Gestures and metaphors as indicators of conceptual understanding of sedimentary systems

    NASA Astrophysics Data System (ADS)

    Riggs, E. M.; Herrera, J. S.

    2012-12-01

    Understanding the geometry and evolution of sedimentary systems and sequence stratigraphy is crucial to the development of geoscientists and engineers working in the petroleum industry. There is a wide variety of audiences within industry who require relatively advanced instruction in this area of geoscience, and there is an equally wide array of approaches to teaching this material in the classroom and field. This research was undertaken to develop a clearer picture of how conceptual understanding in this area of sedimentary geology grows as a result of instruction and how instructors can monitor the completeness and accuracy of student thinking and mental models. We sought ways to assess understanding that did not rely on model-specific jargon but rather was based in physical expression of basic processes and attributes of sedimentary systems. Advances in cognitive science and educational research indicate that a significant part of spatial cognition is facilitated by gesture, (e.g. giving directions, describing objects or landscape features). We aligned the analysis of gestures with conceptual metaphor theory to probe the use of mental image-schemas as a source of concept representation for students' learning of sedimentary processes. In order to explore image schemas that lie in student explanations, we focused our analysis on four core ideas about sedimentary systems that involve sea level change and sediment deposition, namely relative sea level, base level, and sea-level fluctuations and resulting basin geometry and sediment deposition changes. The study included 25 students from three U.S. Midwestern universities. Undergraduate and graduate-level participants were enrolled in senior-level undergraduate courses in sedimentology and stratigraphy. We used semi-structured interviews and videotaping for data collection. We coded the data to focus on deictic, iconic, and metaphoric gestures, and coded interview transcripts for linguistic metaphors using the

  8. Recent benthic foraminifera and sedimentary facies distribution of the Abu Dhabi (United Arab Emirates) coastline

    NASA Astrophysics Data System (ADS)

    Fiorini, Flavia; Lokier, Stephen W.

    2014-05-01

    The distribution of benthic foraminifera and sedimentary facies from Recent coastline environments adjacent to the coastline of Abu Dhabi (UAE) was studied in detail with the aim to: 1) provide reliable analogs for understanding and interpreting the depositional environment of ancient shallow-marine sediments from the UAE; 2) assess any modifications in the distribution of benthic environments and sedimentary facies in an area affected by significant anthropogenic activities - particular construction and land reclamation. A total of 100 sea-floor sediment samples were collected in different shallow-marine sedimentary environments (nearshore shelf, beach-front, channels, ooid shoals, lagoon and mangals) close to the coastline of Abu Dhabi Island. Where possible, we revisited the sampling sites used in several studies conducted in the middle of last century (prior to any significant anthropogenic activities) to assess temporal changes in Recent benthic foraminifera and sedimentary facies distribution during the last 50 years. Five foraminiferal assemblages were recognized in the studied area. Species with a porcellaneous test mainly belonging to the genera Quinqueloculina, Triloculina, Spiroloculina, Sigmoilinita are common in all studied areas. Larger benthic foraminifera Peneroplis and Spirolina are particularly abundant in samples collected on seaweed. Hyaline foraminifera mostly belonging to the genera Elphidium, Ammonia, Bolivina and Rosalina are also common together with Miliolidae in the nearshore shelf and beach front. Agglutinated foraminifera (Clavulina, Textularia, Ammobaculites and Reophax) are present in low percentages. The species belonging to the genera Ammobaculites and Reophax are present only in the finest grain samples particularly in lagoons and mangal environments and have not been reported previously in the studied area. The majority of the ooid shoal sediments, the coarser sediments of the beach-front and samples collected in dredged channels

  9. Conditional Convergence of Numerical Series

    ERIC Educational Resources Information Center

    Gomez, E.; Plaza, A.

    2002-01-01

    One of the most astonishing properties when studying numerical series is that the sum is not commutative, that is the sum may change when the order of its elements is altered. In this note an example is given of such a series. A well-known mathematical proof is given and a MATLAB[C] program used for different rearrangements of the series…

  10. Students' Conception of Infinite Series

    ERIC Educational Resources Information Center

    Martinez-Planell, Rafael; Gonzalez, Ana Carmen; DiCristina, Gladys; Acevedo, Vanessa

    2012-01-01

    This is a report of a study of students' understanding of infinite series. It has a three-fold purpose: to show that students may construct two essentially different notions of infinite series, to show that one of the constructions is particularly difficult for students, and to examine the way in which these two different constructions may be…

  11. Summing Certain p-Series.

    ERIC Educational Resources Information Center

    Fay, Temple H.

    1997-01-01

    Presents an exercise suitable for beginning calculus students that may give insight into series representations and allow students to see some elementary application of these representations. The Fourier series is used to approximate by taking sums of trigonometric functions of the form sin(ns) and cos(nx) for n is greater than or = zero. (PVD)

  12. Complex Landscape Terms in Seri

    ERIC Educational Resources Information Center

    O'Meara, Carolyn; Bohnemeyer, Jurgen

    2008-01-01

    The nominal lexicon of Seri is characterized by a prevalence of analytical descriptive terms. We explore the consequences of this typological trait in the landscape domain. The complex landscape terms of Seri classify geographic entities in terms of their material make-up and spatial properties such as shape, orientation, and merological…

  13. Economic Time-Series Page.

    ERIC Educational Resources Information Center

    Bos, Theodore; Culver, Sarah E.

    2000-01-01

    Describes the Economagic Web site, a comprehensive site of free economic time-series data that can be used for research and instruction. Explains that it contains 100,000+ economic data series from sources such as the Federal Reserve Banking System, the Census Bureau, and the Department of Commerce. (CMK)

  14. Transfer of Mathematical Knowledge: Series

    ERIC Educational Resources Information Center

    Akgun, Levent; Isik, Cemalettin; Tatar, Enver; Isleyen, Tevfik; Soylu, Yasin

    2012-01-01

    The aim of this study is to explain students' ability to transfer their knowledge about mathematical series to the problems that they encounter. The data of the study were obtained by using two different tests, namely "Problem Solving Test (PST)" and "Series Character Identification Test (SCT)" which were developed by the…

  15. Convergence of a Catalan Series

    ERIC Educational Resources Information Center

    Koshy, Thomas; Gao, Zhenguang

    2012-01-01

    This article studies the convergence of the infinite series of the reciprocals of the Catalan numbers. We extract the sum of the series as well as some related ones, illustrating the power of the calculus in the study of the Catalan numbers.

  16. The effects of small dam removal on the distribution of sedimentary contaminants.

    PubMed

    Ashley, Jeffrey T F; Bushaw-Newton, Karen; Wilhelm, Matt; Boettner, Adam; Drames, Gregg; Velinsky, David J

    2006-03-01

    With increasing concern over degradation of aquatic resources, issues of liability, and maintenance costs, removal of small dams has become increasing popular. Although the benefits of removal seem to outweigh the drawbacks, there is a relative paucity of studies documenting the extent and magnitude of biological and chemical changes associated with dam removal, especially those evaluating potential changes in contaminant inventories. In August and November of 2000, a run-of-the-river dam on Manatawny Creek (southeast Pennsylvania) was removed in a two-stage process. To assess the effects of dam removal on the contaminant redistribution within the creek, sedimentary concentrations of polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and trace metals (Cd, Cr, Cu, Ni, Pb, Zn) were evaluated prior to and several months after removal. Pre- and post-removal analyses revealed elevated and spatially variable concentrations of total PAHs (ranging from approximately 200 to 81,000 ng(g dry weight) and low to moderate concentrations of trace metals and PCBs. The concentrations of these sedimentary contaminants pre- versus post-removal were not significantly different. Additionally, though the impoundment received storm water run-off and associated contaminants from the adjacent city of Pottstown, the total inventory of fine-grain sediments in the impoundment prior to removal was very low. The removal of the low-level Manatawny Creek dam did not significantly redistribute contaminants downstream. However, each dam removal should be assessed on a case by case basis where the potential of sedimentary contaminant redistribution upon dam removal exists.

  17. Permo-Carboniferous sedimentary basins related to the distribution of planetary cryptoblemes

    USGS Publications Warehouse

    Windolph, J.F.

    1997-01-01

    Massive/high velocity solar, galactic, and cosmic debris impacting the Earths surface may account for the enormous energy required for the formation of Permo-Carboniferous sedimentary basins and related mountain building orogenies. Analysis of satellite immagry, sea floor sonar, geophysical data, and geotectonic fabrics show a strong correlation throughout geologic time between sedimentary basin origin and planetary cryptoblemes. Cryptoblemes are subtile, multi-ringed, radial centric impact shock signatures covering the entire terrestrial surface and ocean floors, having a geometry and distribution strikingly similar to the surfaces of the lunar planetary bodies in the solar system. Investigations of Permo-Carboniferous basins show an intensely overprinted pattern of cryptoblemes coinciding with partial obliteration and elliptical compression of pre-existing basins and accompanying shock patterns. Large distorted cryptoblemes may incorporate thin skin deformation, localized sediment diagenesis, regional metamorphism, and juxtaposed exotic terrains. These data, related to basin morphogenic symmetry, suggest that large episodic impact events are the primary cause of tectonogenic features, geologic boundary formation and mass extinction episodes on the planet Earth. Plate tectonics may be only a slow moving, low energy secondary effect defined and set in motion by megacosmic accretion events. Permo-Carboniferous sediments of note are preserved or accumulated in relatively small rectangular to arcuate rift valleys and synclinal down warps, such as the Narraganset basin of Massachusetts, USA, and Paganzo basin in Argentina, S.A. These deposits and depocenters may originate from dynamic reinforcement/cancellation impact effects, as can be seen in the Basin Range of Nevada and Utah, USA. Large circular to oval sedimentary basins commonly include internal ring structures indicating post depositional subsidence and rebound adjustments with growth faulting, notable in the

  18. [Over one hundred year sedimentary record of polycyclic aromatic hydrocarbons in the Andaman Sea, Malaysia].

    PubMed

    Wu, Yu-Ling; Wang, Xin-Hong; Li, Yong-Yu; Hong, Hua-Sheng; Li, He-Yang; Yin, Ming-Duan

    2009-09-15

    Polycyclic aromatic hydrocarbons (PAHs) in a sediment core collected from Langkawi Island of the Andaman Sea, Malaysia were determined by GC/MS, the vertical variations of concentration and distributions of PAHs were investigated. In combining with 210Pb-dating, the PAHs sedimentary record in the last 100 years was reconstructed and their possible sources were also discussed. The sigmaPAH concentration ranged from 13.2-60.1 ng x g(-1) in the whole sedimentary section (0-56 cm) with the dominant compounds of phenanthrene, naphthalene and perylene. The sediments contaminated to a lesser extent comparing with the surrounding waters. Before the 1920s, the concentrations of PAHs were considered to be the background level, which was implied from the natural inputs. The historical records of PAHs in the core showed that two distinct peaks which represented the input time of 1960s and 1980s, respectively, inferred that there were some relatively dramatically land-based inputs, and human activities leaded a clear impact to these waters during these periods. Furthermore, PAHs diagnostic ratios indicated that PAHs in the core sediments were mainly of pyrolytic origin (combustion), accompanied with minor petroleum origin. These were related with agriculture, industry, ocean import and export, and shipping activities in the surrounding regions. Meanwhile as the vital communication line, the marine transportation of the Strait of Malacca had influenced the environmental quality of the Andaman Sea. Meanwhile, based on the sedimentary record, PAHs concentrations were found to correlate positively with humanism activities and socioeconomic development (Gross Domestic Production) in the surrounding regions.

  19. The organic geochemistry of black sedimentary barite: significance and implications of trapped fatty acids

    USGS Publications Warehouse

    Miller, R.E.; Brobst, D.A.; Beck, P.C.

    1977-01-01

    Fatty acids isolated in sedimentary black barite (BaSO4) from Arkansas and Nevada were identified by gas chromatography-mass spectroscopy. The dominant or major fatty acids found in these beds of barite are C16:0, C18:0, and C18:1. The occurrence and distribution of these acids in this type of rock may serve as "molecular fingerprints" of microbial biogeochemical processes. The organic matter and associated microorganisms are shown to be trapped within the finely crystalline barite, thus forming a closed system for microbial diagenesis. Important differences that occur in the distribution of the lesser or minor fatty acids probably result from: (1) the nature of the progenitor organic detritus in the environment of barite deposition: and (2) the subsequent degree of microbiological alteration of the parent organic debris swept into and trapped in the depositional environment. Three general models of sedimentary environments are proposed in which anoxic conditions may prevail and where barium sulfate (BaSO4) may precipitate: (1) in a silled basin with semi-restricted circulation; (2) on an outer continental shelf where the slope is encroached upon by water of the oxygen minimum layer; (3) on a low-energy, inner shelf or semi-restricted embayment impinged by a wedge of anoxic water. The major geochemical and geological parameters which are believed to be the significant factors controlling the formation and high grade of these organic-rich, black bedded barites are: (1) a unique source of barium-rich fluid that only contains trace amounts of other elements; (2) the presence of an anoxic bottom environment within the depositional basin; (3) a reflux source of sulfate ion; (4) an adequate source of organic matter. The results of this study may serve as guidelines for future exploration in similar, untested sedimentary basins, especially those with rocks of middle Paleozoic age. ?? 1977.

  20. Alteration of immature sedimentary rocks on Earth and Mars. Recording Aqueous and Surface-atmosphere Processes

    SciTech Connect

    Cannon, Kenneth M.; Mustard, John F.; Salvatore, Mark R.

    2015-03-05

    The rock alteration and rind formation in analog environments like Antarctica may provide clues to rock alteration and therefore paleoclimates on Mars. Clastic sedimentary rocks derived from basaltic sources have been studied in situ by martian rovers and are likely abundant on the surface of Mars. Moreover, how such rock types undergo alteration when exposed to different environmental conditions is poorly understood compared with alteration of intact basaltic flows. Here we characterize alteration in the chemically immature Carapace Sandstone from Antarctica, a terrestrial analog for martian sedimentary rocks. We employ a variety of measurements similar to those used on previous and current Mars missions. Laboratory techniques included bulk chemistry, powder X-ray diffraction (XRD), hyperspectral imaging and X-ray absorption spectroscopy. Through these methods we find that primary basaltic material in the Carapace Sandstone is pervasively altered to hydrated clay minerals and palagonite as a result of water–rock interaction. A thick orange rind is forming in current Antarctic conditions, superimposing this previous aqueous alteration signature. The rind exhibits a higher reflectance at visible-near infrared wavelengths than the rock interior, with an enhanced ferric absorption edge likely due to an increase in Fe3+ of existing phases or the formation of minor iron (oxy)hydroxides. This alteration sequence in the Carapace Sandstone results from decreased water–rock interaction over time, and weathering in a cold, dry environment, mimicking a similar transition early in martian history. This transition may be recorded in sedimentary rocks on Mars through a similar superimposition mechanism, capturing past climate changes at the hand sample scale. These results also suggest that basalt-derived sediments could have sourced significant volumes of hydrated minerals on early Mars due to their greater permeability compared with intact igneous rocks.

  1. Dissolved sulfide-catalyzed precipitation of disordered dolomite: Implications for the formation mechanism of sedimentary dolomite

    NASA Astrophysics Data System (ADS)

    Zhang, Fangfu; Xu, Huifang; Konishi, Hiromi; Kemp, Joshua M.; Roden, Eric E.; Shen, Zhizhang

    2012-11-01

    Dolomite is a common mineral in the rock record. However, the rarity of modern dolomite and the notorious difficulty in synthesizing dolomite abiotically under normal Earth-surface conditions result in the long-standing “dolomite problem” in sedimentary geology. Some modern dolomites are associated with sediments where microbial sulfate reduction is active; however, the role of sulfate-reducing bacteria in dolomite formation is still under debate. In this study, we tested the effect of dissolved sulfide on the precipitation of Ca-Mg carbonates, which has been never explored before although dissolved sulfide is one of the major products of microbial sulfate reduction. Our results demonstrated that dissolved sulfide with a concentration of as low as several millimoles can enhance the Mg2+ incorporation into the calcitic structure, and promote the crystallization of high magnesian calcite and disordered dolomite. We also conducted seeded precipitation in experimental solutions containing dissolved sulfide, which showed that calcite seeds can inhibit the precipitation of aragonite and monohydrocalcite (CaCO3·H2O), and induce more Mg2+ incorporation. We propose that accumulated dissolved sulfide in pore waters in organic-rich sediments may trigger the precipitation of disordered dolomite which can be considered as a precursor of some sedimentary dolomite. Our adsorption experiments revealed a strong adsorption of dissolved sulfide onto calcite faces. We suggest that adsorbed dissolved sulfide can lower the energy barrier to the dehydration of Mg2+-water complexes on the growing carbonate surfaces. This study sheds new light on understanding the role of sulfate-reducing bacteria in dolomite formation and the formation mechanism of sedimentary dolomite.

  2. Sorting out compositional trends in sedimentary rocks of the Bradbury group (Aeolis Palus), Gale crater, Mars

    NASA Astrophysics Data System (ADS)

    Siebach, K. L.; Baker, M. B.; Grotzinger, J. P.; McLennan, S. M.; Gellert, R.; Thompson, L. M.; Hurowitz, J. A.

    2017-02-01

    Sedimentary rocks are composed of detrital grains derived from source rocks, which are altered by chemical weathering, sorted during transport, and cemented during diagenesis. Fluvio-lacustrine sedimentary rocks of the Bradbury group, observed on the floor of Gale crater by the Curiosity rover during its first 860 Martian solar days, show trends in bulk chemistry that are consistent with sorting of mineral grains during transport. The Bradbury group rocks are uniquely suited for sedimentary provenance analysis because they appear to have experienced negligible cation loss (i.e., open-system chemical weathering) at the scale of the Alpha Particle X-ray Spectrometer bulk chemistry analyses based on low Chemical Index of Alteration values and successful modeling of >90% of the (volatile-free) targets as mixtures of primary igneous minerals. Significant compositional variability between targets is instead correlated to grain-size and textural characteristics of the rocks; the coarsest-grained targets are enriched in Al2O3, SiO2, and Na2O, whereas the finer-grained targets are enriched in mafic components. This is consistent with geochemical and mineralogical modeling of the segregation of coarse-grained plagioclase from finer-grained mafic minerals (e.g., olivine and pyroxenes), which would be expected from hydrodynamic sorting of the detritus from mechanical breakdown of subalkaline plagioclase-phyric basalts. While the presence of a distinctive K2O-rich stratigraphic interval shows that input from at least one distinctive alkali-feldspar-rich protolith contributed to basin fill, the dominant compositional trends in the Bradbury group are consistent with sorting of detrital minerals during transport from relatively homogeneous plagioclase-phyric basalts.

  3. Sedimentary facies and history of Upper Jurassic (Oxfordian) Smackover Formation in Conecuh embayment of south Alabama

    SciTech Connect

    Esposito, R.A.; King, D.T. Jr.

    1986-05-01

    The Upper Jurassic (Oxfordian) Smackover Formation is an important petroleum-bearing unit in the deep subsurface of the gulf rim. The authors studied the sedimentary facies and sedimentary history of the Smackover in Escambia County, Alabama. The wells studied form an east-west strike section across the Conecuh embayment in south Alabama. In the central part of the embayment, the Smackover is 350 ft (107 m) thick and consists of a vertical sequence of the following correlative sedimentary facies. In stratigraphic order, they are: (1) basal, shallow-water facies that rests conformably on the underlying Norphlet and forms a discontinuous interval a few feet thick, consisting of algal-laminated mudstones, sandy packstones and grainstones, and clast horizons; (2) basinal, deep-water facies, 175 ft (53 m) thick, consisting of resedimented debris beds (oolitic-pisolitic-graded beds, 8 in or 24 cm thick) intercalated with laminated, very argillaceous mudstone and wackestone; (3) parallel and wavy-laminated, sparsely fossiliferous packstone and wackestone, 80 ft (24 m) thick, interpreted as a carbonate slope deposit that accumulated below storm wave base; (4) bioturbated oolitic, pelletal, and fossiliferous packstone with faint relict laminations, 45 ft (14 m) thick, containing abundant Thalassinoides and Zoophycus traces and interpreted as below normal wave base deposits; and (5) oolitic and fossiliferous grainstone, 50 ft (15 m) thick, interpreted as deposits formed above wave base (shelf-platform deposits). The above sequence suggests progradation of a carbonate shelf. This progradation probably followed the rapid eustatic sea-level rise of the Oxfordian.

  4. Sediment Flux from Stratigraphy: Insights from <1 Ma to >300 Ma Sedimentary Archives

    NASA Astrophysics Data System (ADS)

    Romans, B.; Mason, C. C.; Eriksson, K. A.

    2014-12-01

    Tectonic or climate signals that originate in net-erosional catchments are transmitted down-system as sediment. The accumulation of that sediment in net-depositional regions and preservation as stratigraphy can be accessed and used to reconstruct signal generation and propagation. Studies of modern to <20 ka sedimentary systems suggest that signal propagation (or lack thereof) is, in part, controlled by the size, relief, and other morphologic characteristics of sediment-production segments. Thus, it's critical to measure, estimate, or infer aspects of the feeder catchment when reconstructing system behavior from sedimentary deposits. Here, we present results from two studies aimed at determining paleo-sediment flux from stratigraphic archives. The first study uses outcropping middle Pleistocene (~0.6 Ma) alluvial-fan deposits in the Panamint Mountains, California, to investigate the relationship of sediment supply to stratigraphic architecture in a small catchment-fan system. The youth of this system allows us to estimate fan volumes from facies architecture and depositional system dimensions based on catchment-area to fan-area relationships of nearby modern systems. These data, combined with preliminary cosmogenic radionuclide-derived paleo-denudation rates, provide an opportunity to examine the nature of erosional signal propagation. The second study examines much older, Upper Mississippian (~325 Ma), fluvial and deltaic strata. Absolute chronologic tools to calculate centennial-millennial rates in deep-time sedimentary archives do not yet exist. Here, we use the extraordinary tidal rhythmite deposits of the Pride Shale in the Appalachian Basin as a high-resolution chronometer to constrain the duration of basin filling. We then use the scale of fluvial channel bodies in the underlying and overlying units combined with climate-specific empirical relationships derived from modern systems to estimate the size of the paleo-catchment. The resultant estimates of

  5. Detecting and correcting for paleomagnetic inclination shallowing of sedimentary rocks: A review

    NASA Astrophysics Data System (ADS)

    Li, Yong-Xiang; Kodama, Kenneth

    2016-02-01

    Magnetic anisotropy and the elongation/inclination (E-I) approaches have been increasingly employed as two important means for detecting and correcting the paleomagnetic inclination shallowing in sedimentary rocks that was first recognized sixty years ago. Both approaches are based on certain assumptions, and thus have advantages and intrinsic limitations in investigating shallow inclinations in sedimentary rocks. The E-I approach is relatively easy to use, but it needs a large dataset to adequately sample paleomagnetic directions due to paleosecular variation of the geomagnetic field. Also, slow sediment accumulation rates and local tectonics could lead to under- or over-corrections using the E-I approach. For the magnetic anisotropy technique, labor-intensive, sophisticated laboratory rock magnetic experiments are required in order to accurately determine both bulk magnetic anisotropy of remanence-carrying grains and magnetic anisotropy of an individual particle, i.e., "a" factor, of samples. Our review shows that, despite the intensive laboratory work necessary for applying anisotropy-based inclination corrections, it is worth investing the effort. In addition, the joint use of magnetic susceptibility and remanence anisotropy measurements as well as detailed rock magnetic measurements for determining the particle anisotropy "a" factor have the advantage of retrieving direct evidence of inclination shallowing and correcting for it with high confidence. We caution against use of either of the two approaches without full appreciation of the underlying assumptions and intrinsic limitations of each technique. The use and comparison of both techniques could provide the most robust inclination shallowing correction for sedimentary rocks.

  6. The Hidden Watershed's Journals: the Informational Characteristics of Biomarkers in Sedimentary Deposits

    NASA Astrophysics Data System (ADS)

    Guerrero, F. J.; Hatten, J. A.

    2014-12-01

    The historical reconstruction of past environmental changes in watersheds is essential to understand watershed response to disturbances and how those diturbances could affect the provision of valuable goods like water. That reconstruction requires the interpretation of natural records, mainly associated to sedimentary deposits that store detailed information in the form of specific biogenic molecules (i.e. biomarkers). In forested watersheds terrestrial vegetation is an important source of biomarkers like those associated to Lignin, a complex organic polymer used by plants to provide physical support in its tissues. Through litter inputs Lignin is deposited in soils and then is transported to sedimentary environments by rivers (e.g. floodplains, lake bottoms), serving as a source of information about vegetation changes in watersheds. In spite of the critical character of the information extracted from biomarkers in sedimentary records, the very concept of information is still used in a metaphorical sense, even though it was formally defined more than 60 years ago and has been applied extensively in ecology (e.g. Shannon's diversity index). Furthermore, sophisticated techniques are being used to deliver more complex molecular data that require examination and validation as indicators for watershed historical reconstructions. My research aims to explore the applicability of some information metrics (i.e. diversity indices, information coefficients) to a diverse molecular set derived from the chemical depolymerization of lignin deposited in floodplains and lake sediments in different basins. This approach attempts to assess the informational characteristics of Lignin as an indicator of natural/human-induced perturbations in forested watersheds. The formal assessment of the informational characteristics of natural records could have a profound impact not only in our methodological approaches but also in our philosophical view about information and communication in

  7. The Lusi eruption and implications for understanding fossil piercement structures in sedimentary basins

    NASA Astrophysics Data System (ADS)

    Svensen, Henrik; Mazzini, Adriano; Planke, Sverre; Hadi, Soffian

    2016-04-01

    The Lusi eruption started in northeast Java, Indonesia, on May 29th 2006, and it has been erupting rocks, mud, water, and gas ever since. We have been doing field work and research on Lusi ever since the eruption commenced. This work was initially motivated from studying the initiation of a mud volcano. However, the longevity of the eruption has made it possible to describe and monitor the lifespan of this unique piercement structure. . One of the first-order questions regarding the eruption is how it should be classified and if there are any other modern or fossil analogues that can place Lusi in a relevant geological context. During the initial stages of eruption, Lusi was classified as a mud volcano, but following geochemical studies the eruption did not show the typical CH4-dominated gas composition of other mud volcanoes and the temperature was also too high. Moreover, mud volcano eruptions normally last a few days, but Lusi never stopped during the past decade. In particular, the crater fluid geochemistry suggests a connection to the neighboring volcanic complex. Lusi represent a sedimentary hosted hydrothermal system. This opens up new possibilities for understanding fossil hydrothermal systems in sedimentary basins, such as hydrothermal vent complexes and breccia-pipes found in sedimentary basins affected by the formation of Large igneous provinces. We will present examples from the Karoo Basin (South Africa) and the Vøring Basin (offshore Norway) and discuss how Lusi can be used to refine existing formation models. Finally, by comparing Lusi to fossil hydrothermal systems we may get insight into the processes operating at depth where the Lusi system interacts with the igneous rocks of the neighbouring volcanic arc.

  8. Evidence for the preservation of technogenic tritiated organic compounds in an estuarine sedimentary environment.

    PubMed

    Croudace, Ian W; Warwick, Phillip E; Morris, Jenny E

    2012-06-05

    The macrotidal Severn Estuary (southwestern UK) has received a broad range of industrial discharges since the beginning of the Industrial Revolution. A more recent anthropogenic input to the estuary has been technogenic tritium (specifically organically bound tritium, OBT). This was derived from a specialized industrial laboratory producing custom radiolabeled compounds for life science research and diagnostic testing from 1980 until 2008. While it was generally acknowledged that the radiological impact of the tritium discharges into the Estuary was small, public concern motivated the company and regulatory agencies to commission several research studies from 1998 to 2005 to better understand their environmental impact. This study examined OBT interaction with estuarine sediment by acquiring a broad range of geochemical and sedimentological data from a suite of sediment cores collected from the northern side of the Estuary. Two important observations are that the OBT compounds are strongly bound to the clay/silt fraction of sediment and that the down-core OBT profiles in intertidal and subtidal sediments are broadly similar to the discharge record. Geochemical and chronometric methods (Cu, Pb and Zn elemental profiles, (210)Pb, (137)Cs) provide important corroboration of the OBT record. A key additional piece of evidence that firmly authenticated the established chronology was the discovery of a previously unreported sedimentary marker layer that was generated by a major storm surge that occurred on December 13, 1981. Although this study has provided clear evidence of systematic accumulation of OBT in sedimentary sinks of the region, an estimation of its depositional inventory shows it represents only a small fraction of the total discharge. This modest retention in the principal sedimentary sinks of the Severn Estuary system reflects the particular dynamics of this highly macrotidal sediment starved estuary.

  9. Flexure and faulting of sedimentary host rocks during growth of igneous domes, Henry Mountains, Utah

    USGS Publications Warehouse

    Jackson, M.D.; Pollard, D.D.

    1990-01-01

    A sequence of sedimentary rocks about 4 km thick was bent, stretched and uplifted during the growth of three igneous domes in the southern Henry Mountains. Mount Holmes, Mount Ellsworth and Mount Hillers are all about 12 km in diameter, but the amplitudes of their domes are about 1.2, 1.85 and 3.0 km, respectively. These mountains record successive stages in the inflation of near-surface diorite intrusions that are probably laccolithic in origin. The host rocks deformed along networks of outcrop-scale faults, or deformation bands, marked by crushed grains, consolidation of the porous sandstone and small displacements of sedimentary beds. Zones of deformation bands oriented parallel to the beds and formation contacts subdivided the overburden into thin mechanical layers that slipped over one another during doming. Measurements of outcrop-scale fault populations at the three mountains reveal a network of faults that strikes at high angles to sedimentary beds which themselves strike tangentially about the domes. These faults have normal and reverse components of slip that accommodated bending and stretching strains within the strata. An early stage of this deformation is displayed at Mount Holmes, where states of stress computed from three fault samples correlate with the theoretical distribution of stresses resulting from bending of thin, circular, elastic plates. Field observations and analysis of frictional driving stresses acting on horizontal planes above an opening-mode dislocation, as well as the paleostress analysis of faulting, indicate that bedding-plane slip and layer flexure were important components of the early deformation. As the amplitude of doming increased, radial and circumferential stretching of the strata and rotation of the older faults in the steepening limbs of the domes increased the complexity of the fault patterns. Steeply-dipping, map-scale faults with dip-slip displacements indicate a late-stage jostling of major blocks over the central

  10. Sedimentary environments and preservation biases limit sulfur isotope fractionation observed in pyrite, despite large microbial fractionations

    NASA Astrophysics Data System (ADS)

    Halevy, I.; Wing, B. A.; Wenk, C.; Guimond, C.

    2015-12-01

    Microbial S isotope fractionations close to the thermodynamic fractionation between sulfate and sulfide (~70‰) are encountered only at the slowest rates of sulfate reduction in laboratory cultures. In turn, the slowest laboratory reduction rates overlap with only the highest values of cell-specific sulfate reduction rates measured in marine sediments. This chain-of-logic implies that sulfate-reducing microbes in the marine sedimentary biosphere fractionate S isotopes at magnitudes close to the thermodynamic limit. Recent observations from sulfate-poor environments indicate that fractionations are large even at micromolar sulfate concentrations, in agreement with model predictions of near-thermodynamic S isotope fractionation at these sulfate concentrations as long as cell-specific sulfate reduction rates are low. Despite the expectation of large microbial fractionations, pyrite in both modern marine sediments and Phanerozoic sedimentary rocks records apparent fractionations ranging from 0 to more than 70‰. We suggest that the observed range of modern marine and geologic apparent fractionations recorded in pyrite does not reflect variability in intrinsic microbial behavior, but an early diagenetic modulation of large microbial fractionations, which are pinned to the thermodynamic limit by the low natural rates of sulfate reduction. With a diagenetic model developed in this study, we show that the entire range of apparent fractionations is possible with microbial fractionations at the thermodynamic limit. Apparent fractionations depend on a variety of physical parameters of the sedimentary environment like sedimentation rate, porosity, and organic matter content, most of which correlate with water depth. These findings, in combination with knowledge about the preservation potential of sediments deposited at different depths, make predictions for the observed geologic range of apparent fractionations, and ways in which it differs from the range in modern marine

  11. Influence of dredging on sedimentary arsenic release for a tide-influenced waterfront body.

    PubMed

    Wang, Hua; Zhou, Yiyi; Pang, Yong; Wang, Xianmin

    2014-09-01

    We evaluated the influence of sediment dredging on sedimentary As release for the Inner Lake, a typical tide-influenced waterfront body in the middle to lower reaches of the Yangtze River in Zhengjiang, China. By field investigation and laboratory experiment, the As content in the deposited sediment before dredging was analyzed and the relationship between dynamic disturbance and sedimentary As release intensity was established. Using a numerical model in which the factors of water current, suspended sediment, and As were coupled, the processes of As migration were simulated for typical years and tidal cycles before and after dredging. The results show that: (i) the amounts of sedimentary As release during the tidal cycles in the flood season and the dry season after dredging were reduced by 14.6 and 28.1%, respectively, compared with before dredging; (ii) after removal of the surface polluted sediment, the annual volumes of internal released As in the high-water year, common-water year, and low-water year were decreased to 11.89, 4.94, and 4.89 Mg, respectively; and (iii) the highest reduction rate could reach 27.5% in the common-water year, while the lowest was 10.92% in the high-water year because the massive water exchange with the Yangtze River in the high-water year resulted in an enhanced dynamic disturbance that played a more dominating role in the internal As release than the surface sediment removal. The results of this study may be useful for other researchers of water environment protection for waterfront bodies.

  12. Alteration of immature sedimentary rocks on Earth and Mars: Recording aqueous and surface-atmosphere processes

    NASA Astrophysics Data System (ADS)

    Cannon, Kevin M.; Mustard, John F.; Salvatore, Mark R.

    2015-05-01

    Rock alteration and rind formation in analog environments like Antarctica may provide clues to rock alteration and therefore paleoclimates on Mars. Clastic sedimentary rocks derived from basaltic sources have been studied in situ by martian rovers and are likely abundant on the surface of Mars. However, how such rock types undergo alteration when exposed to different environmental conditions is poorly understood compared with alteration of intact basaltic flows. Here we characterize alteration in the chemically immature Carapace Sandstone from Antarctica, a terrestrial analog for martian sedimentary rocks. We employ a variety of measurements similar to those used on previous and current Mars missions. Laboratory techniques included bulk chemistry, powder X-ray diffraction (XRD), hyperspectral imaging and X-ray absorption spectroscopy. Through these methods we find that primary basaltic material in the Carapace Sandstone is pervasively altered to hydrated clay minerals and palagonite as a result of water-rock interaction. A thick orange rind is forming in current Antarctic conditions, superimposing this previous aqueous alteration signature. The rind exhibits a higher reflectance at visible-near infrared wavelengths than the rock interior, with an enhanced ferric absorption edge likely due to an increase in Fe3+ of existing phases or the formation of minor iron (oxy)hydroxides. This alteration sequence in the Carapace Sandstone results from decreased water-rock interaction over time, and weathering in a cold, dry environment, mimicking a similar transition early in martian history. This transition may be recorded in sedimentary rocks on Mars through a similar superimposition mechanism, capturing past climate changes at the hand sample scale. Our results also suggest that basalt-derived sediments could have sourced significant volumes of hydrated minerals on early Mars due to their greater permeability compared with intact igneous rocks.

  13. Recirculation System for Geothermal Energy Recovery in Sedimentary Formations: Laboratory Experiments and Numerical Simulations

    NASA Astrophysics Data System (ADS)

    Elkhoury, J. E.; Detwiler, R. L.; Serajian, V.; Bruno, M. S.

    2012-12-01

    Geothermal energy resources are more widespread than previously thought and have the potential for providing a significant amount of sustainable clean energy worldwide. In particular, hot permeable sedimentary formations provide many advantages over traditional geothermal recovery and enhanced geothermal systems in low permeability crystalline formations. These include: (1) eliminating the need for hydraulic fracturing, (2) significant reduction in risk for induced seismicity, (3) reducing the need for surface wastewater disposal, (4) contributing to decreases in greenhouse gases, and (5) potential use for CO2 sequestration. Advances in horizontal drilling, completion, and production technology from the oil and gas industry can now be applied to unlock these geothermal resources. Here, we present experimental results from a laboratory scale circulation system and numerical simulations aimed at quantifying the heat transfer capacity of sedimentary rocks. Our experiments consist of fluid flow through a saturated and pressurized sedimentary disc of 23-cm diameter and 3.8-cm thickness heated along its circumference at a constant temperature. Injection and production ports are 7.6-cm apart in the center of the disc. We used DI de-aired water and mineral oil as working fluids and explored temperatures from 20 to 150 oC and flow rates from 2 to 30 ml/min. We performed experiments on sandstone samples (Castlegate and Kirby) with different porosity, permeability and thermal conductivity to evaluate the effect of hydraulic and thermal properties on the heat transfer capacity of sediments. The producing fluid temperature followed an exponential form with time scale transients between 15 and 45 min. Steady state outflow temperatures varied between 60% and 95% of the set boundary temperature, higher percentages were observed for lower temperatures and flow rates. We used the flow and heat transport simulator TOUGH2 to develop a numerical model of our laboratory setting. Given

  14. Bibliography on the Distribution, Properties, and Uses of Zeolites from Sedimentary Deposits, 1998-2002

    USGS Publications Warehouse

    Sheppard, Richard A.

    2003-01-01

    This bibliography is an alphabetical listing by author of about 1,500 publications and formal releases, including patents and selected abstracts, from the world literature on the distribution, properties, and uses of zeolites from sedimentary deposits for the period 1998-2002. The bibliography is available on a 3.5-inch floppy diskette, which was prepared on a MacintoshTM computer using EndNoteTM software. Computer searches of the bibliography can be made by author, year, title, journal, publisher, and keywords.

  15. Quasi-periodic bedding in the sedimentary rock record of mars

    USGS Publications Warehouse

    Lewis, K.W.; Aharonson, O.; Grotzinger, J.P.; Kirk, R.L.; McEwen, A.S.; Suer, T.-A.

    2008-01-01

    Widespread sedimentary rocks on Mars preserve evidence of surface conditions different from the modern cold and dry environment, although it is unknown how long conditions favorable to deposition persisted. We used 1-meter stereo topographic maps to demonstrate the presence of rhythmic bedding at several outcrops in the Arabia Terra region. Repeating beds are ???10 meters thick, and one site contains hundreds of meters of strata bundled into larger units at a ???10:1 thickness ratio. This repetition likely points to cyclicity in environmental conditions, possibly as a result of astronomical forcing. If deposition were forced by orbital variation, the rocks may have been deposited over tens of millions of years.

  16. Monitoring of Sedimentary Fluxes in Cold Environments: The SEDIBUD (Sediment Budgets in Cold Environments) Programme

    NASA Astrophysics Data System (ADS)

    Beylich, Achim A.

    2014-05-01

    Projected climate change in cold regions is expected to alter melt season duration and intensity, along with the number of extreme rainfall events, total annual precipitation and the balance between snowfall and rainfall. Similarly, changes to the thermal balance are expected to reduce the extent of permafrost and seasonal ground frost and increase active layer depths. These effects will undoubtedly change surface environments in cold regions and 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 is acute in cold climate environments. The International Association of Geomorphologists` (I.A.G. / A.I.G.) SEDIBUD (Sediment Budgets in Cold Environments) Program (2005 - 2017) is addressing this existing key knowledge gap. The central research question of this global group of scientists is to: Assess and model the contemporary sedimentary fluxes in cold climates, with emphasis on both particulate and dissolved components. Research carried out at each of the ca. 50 defined SEDIBUD key test sites varies by program, logistics and available resources, but typically represent interdisciplinary collaborations of geomorphologists, hydrologists, ecologists, permafrost scientists and glaciologists. SEDIBUD has developed manuals and protocols (SEDIFLUX Manual) with a key set of primary surface process monitoring and research data requirements to incorporate results from these diverse projects and allow coordinated quantitative analysis across the program. Defined SEDIBUD key tasks for the coming years include (i) The continued generation and compilation of comparable longer-term datasets on contemporary sedimentary fluxes and sediment yields from SEDIBUD key test sites worldwide, (ii) The continued extension of the SEDIBUD metadata database with these datasets, (iii) The testing of defined SEDIBUD hypotheses (available

  17. Latest Proterozoic to early Cambrian sedimentary-tectonic evolution of a passive margin sequence, northeastern Washington

    SciTech Connect

    Lindsey, K.A.; Gaylord, D.R.

    1987-08-01

    The late Proterozoic to Early Cambrian Three Sisters formation, Addy Quartzite, and Gypsy Quartzite lie near the base of the Cordilleran miogeocline in northeastern Washington. Detailed stratigraphic and sedimentary examination of these units extends understanding of the evolution of western North America. These units were deposited on a newly rifted passive margin and record the final stages of late Proterozoic rifting and the early stages of subsequent early Paleozoic subsidence and transgression. The three Sisters formation, Addy Quartzite, and Gypsy Quartzite are correlative with the Brigham Group in southeastern Idaho and Utah, the Gold Creek Quartzite in northern Idaho, and the Flathead Quartzite in Montana and Wyoming.

  18. Sedimentary, tectonic, and sea-level controls on submarine fan and slope-apron turbidite systems

    USGS Publications Warehouse

    Stow, D.A.V.; Howell, D.G.; Nelson, C.H.

    1984-01-01

    To help understand factors that influence submarine fan deposition, we outline some of the principal sedimentary, tectonic, and sea-level controls involved in deep-water sedimentation, give some data on the rates at which they operate, and evaluate their probable effects. Three depositional end-member systems, two submarine fan types (elongate and radial), and a third nonfan, slope-apron system result primarily from variations in sediment type and supply. Tectonic setting and local and global sea-level changes further modify the nature of fan growth, the distribution of facies, and the resulting vertical stratigraphic sequences. ?? 1984 Springer-Verlag New York Inc.

  19. Tectonics of the circum-Troodos sedimentary cover of Cyprus, from rock magnetic and structural observations

    NASA Astrophysics Data System (ADS)

    Lagroix, France; Borradaile, Graham J.

    2000-04-01

    The calcareous sedimentary cover of the Troodos Ophiolite Complex dips gently away from the Troodos Complex. It has rare, usually open folds and, locally, stylolitic cleavage ( S1). Stylolitic cleavage is ˜50% more effective than primary bedding-stylolites in removing matrix and the variation in the S1 vergence directions are compatible with gravitational sliding radially away from the Troodos range and into sedimentary basins. Two different types of magnetic fabric, anisotropy of magnetic susceptibility (AMS) and anisotropy anhysteretic remanence (AARM), reveal the sequence of preferred orientations of different minerals, and the vergence of their magnetic foliations with respect to bedding reveals the sense of over-shearing of the stratigraphic sequence. AMS defines crystallographic alignments of clay minerals and dimensional alignments of magnetite in the limestones. AARM isolates the preferred dimensional orientation of magnetite. Although traces of magnetite dominate the bulk susceptibility, its anisotropy is low in comparison with phyllosilicates so that AMS essentially records the clay-fabric. Throughout the study area, AMS foliation indicates S-vergence and AMS lineation indicates N-S extension. AMS foliation-vergence indicates shearing of the entire sedimentary cover southward from Troodos. This motion is attributed to gravity sliding controlled by regional uplift to the north. In contrast, AARM foliation indicates a subsequent ESE vergence due to later WNW-ESE extension. The NNE, AARM lineation is a composite of bedding and tectonic fabric contributions that do not directly yield a faithful extension direction. The shapes of the magnetic fabrics indicate that AMS (clay) fabrics have a broad range of shapes about the neutral ellipsoid shape, whereas AARM (magnetite) fabrics are bimodal, with equally developed bedding-oblate and tectonic linear-planar ( L= S) components. Hysteresis properties, plotted on a new three-dimensional diagram, show clearly that

  20. A rapid method for concentrating sedimentary organic matter for vitrinite reflectance analysis.

    USGS Publications Warehouse

    Barker, C.E.

    1982-01-01

    The tecnique discussed in this paper utilizes crushing, high-speed blending, and ultrasonic treatment to mechanically disaggregate rock and release the sedimentary organic matter (OM) in a suitable heavy liquid. This new method can provide freeze-dried concentrated OM in approximately 8 to 24 hours (longer time is necessary for removing carbonate). Under optimal conditions, it is possible to concentrate the OM and prepare a hardened epoxy microscope slide in about 24 hours. Subsequent grinding, polishing, and drying allows microscopic examination of the organic concentrate the next day.-from Author

  1. Langevin equations from time series.

    PubMed

    Racca, E; Porporato, A

    2005-02-01

    We discuss the link between the approach to obtain the drift and diffusion of one-dimensional Langevin equations from time series, and Pope and Ching's relationship for stationary signals. The two approaches are based on different interpretations of conditional averages of the time derivatives of the time series at given levels. The analysis provides a useful indication for the correct application of Pope and Ching's relationship to obtain stochastic differential equations from time series and shows its validity, in a generalized sense, for nondifferentiable processes originating from Langevin equations.

  2. Time series with tailored nonlinearities

    NASA Astrophysics Data System (ADS)

    Räth, C.; Laut, I.

    2015-10-01

    It is demonstrated how to generate time series with tailored nonlinearities by inducing well-defined constraints on the Fourier phases. Correlations between the phase information of adjacent phases and (static and dynamic) measures of nonlinearities are established and their origin is explained. By applying a set of simple constraints on the phases of an originally linear and uncorrelated Gaussian time series, the observed scaling behavior of the intensity distribution of empirical time series can be reproduced. The power law character of the intensity distributions being typical for, e.g., turbulence and financial data can thus be explained in terms of phase correlations.

  3. Biogenic sedimentary structures on a Korean mud flat: Spring-neap variations

    NASA Astrophysics Data System (ADS)

    Lee, Youn-Ho; Koh, Chul-Hwan

    Biogenic sedimentary structures created by dominant benthic animals of a mud flat were investigated in a small embayment at Panweol on the west coast of Korea. Burrows were replicated using the resin casting method on a sufficiently large scale to evaluate their variations statistically. The size and shape of burrows and other traces varied with locations and tidal phases. Burrows of the upper-intertidal crabs Helice tridens sheni and Ilyoplax dentimerosa were T- or I-shaped, vertical and deep whereas those of the mid-intertidal crab Macrophthalmus japonicus were U-shaped, oblique and shallow. The upper-intertidal polychaete Perineris aibuhitensis, a subsurface feeder, had sinuous and highly-branched burrows while the mid-internal one Periserrula leucophryna, a surface feeder, had vertical burrows without subsurface branches. Variations of crab burrows with tidal phases were distinct: The burrows of both H. tridens sheni and M. japonicus were significantly deeper and wider during neap tides than during spring tides. Sediment mounds were common in the upper intertidal zone, while crawling and feeding traces such as trails, trackways and cheliped scrapings were more prominent in the mid-intertidal zone. These traces were also observed in the upper intertidal zone during spring tides when surface sediments became watery. The size of the sediment mounds varied, being largest during neap tides. These biogenic sedimentary structures observed at Panweol were distinctly different from those found near Inchon only 50 km away, probably due to differences in hydrology and sedimentology.

  4. Structural geology of Amazonian-aged layered sedimentary deposits in southwest Candor Chasma, Mars

    USGS Publications Warehouse

    Okubo, C.H.

    2010-01-01

    The structural geology of an outcropping of layered sedimentary deposits in southwest Candor Chasma is mapped using two adjacent high-resolution (1 m/pixel) HiRISE digital elevation models and orthoimagery. Analysis of these structural data yields new insight into the depositional and deformational history of these deposits. Bedding in non-deformed areas generally dips toward the center of west Candor Chasma, suggesting that these deposits are basin-filling sediments. Numerous kilometer-scale faults and folds characterize the deformation here. Normal faults of the requisite orientation and length for chasma-related faulting are not observed, indicating that the local sediments accumulated after chasma formation had largely ceased in this area. The cause of the observed deformation is attributed to landsliding within these sedimentary deposits. Observed crosscutting relationships indicate that a population of sub-vertical joints are the youngest deformational structures in the area. The distribution of strain amongst these joints, and an apparently youthful infill of sediment, suggests that these fractures have been active in the recent past. The source of the driving stress acting on these joints has yet to be fully constrained, but the joint orientations are consistent with minor subsidence within west Candor Chasma.

  5. Nitrogen isotope dynamics and fractionation during sedimentary denitrification in Boknis Eck, Baltic Sea

    NASA Astrophysics Data System (ADS)

    Dähnke, K.; Thamdrup, B.

    2013-01-01

    The global marine nitrogen cycle is constrained by nitrogen fixation as a source of reactive nitrogen, and denitrification or anammox on the sink side. These processes with their respective isotope effects set the marine nitrate 15N-isotope value (δ15N) to a relatively constant average of 5‰. This value can be used to better assess the magnitude of these sources and sink terms, but the underlying assumption is that sedimentary denitrification and anammox, processes responsible for approximately one third of global nitrogen removal, have little to no isotope effect on nitrate in the water column. We investigated the isotope fractionation in sediment incubations, measuring net denitrification and nitrogen and oxygen stable isotope fractionation in surface sediments from the coastal Baltic Sea (Boknis Eck, Northern Germany), a site with seasonal hypoxia and dynamic nitrogen turnover. We found tremendously high denitrification rates, and regardless of current paradigms assuming little fractionation during sediment denitrification, we measured fractionation factors of 18.9‰ for nitrogen and 15.8‰ for oxygen in nitrate. While the input of nitrate to the water column remains speculative, these results challenge the current view of fractionation during sedimentary denitrification and imply that nitrogen budget calculations may need to consider this variability, as both preferential uptake of light nitrate and release of the remaining heavy fraction can significantly alter water column nitrate isotope vales at the sediment-water interface.

  6. Tectonic and sedimentary structures in the northern Chukchi region, Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Hegewald, Anne; Jokat, Wilfried

    2013-07-01

    interpretation of tectonic and sedimentary structures in the northern Chukchi region, Arctic Ocean, is important to enhance our understanding of the tectonic evolution of this region. Therefore, multichannel seismic lines as well as seismic wide-angle reflection and refraction data were acquired in the northern Chukchi region during the RV Polarstern ARK-XXIII/3 summer expedition in 2008. These data have been processed and interpreted for the three main geological provinces (Chukchi Plateau, Chukchi Abyssal Plain, and Mendeleev Ridge) to describe the sedimentary and basement structures of the northern Chukchi region. Furthermore, using the age control of five exploration wells drilled near the coast of Alaska in combination with additional seismic reflection lines located on the Chukchi Shelf, we were able to date sediment horizons within the research area. In total, six sediment horizons with ages between Barremian/Hauterivian and the Top Miocene were identified. Especially, the Top Oligocene horizon forms a pronounce unconformity on the Chukchi Plateau and on the Mendeleev Ridge flanks. The origin of this unconformity can be associated with the opening of the Fram Strait indicating a significant change in the Arctic Ocean current system.

  7. Genetic data from algae sedimentary DNA reflect the influence of environment over geography.

    PubMed

    Stoof-Leichsenring, Kathleen R; Herzschuh, Ulrike; Pestryakova, Luidmila A; Klemm, Juliane; Epp, Laura S; Tiedemann, Ralph

    2015-08-11

    Genetic investigations on eukaryotic plankton confirmed the existence of modern biogeographic patterns, but analyses of palaeoecological data exploring the temporal variability of these patterns have rarely been presented. Ancient sedimentary DNA proved suitable for investigations of past assemblage turnover in the course of environmental change, but genetic relatedness of the identified lineages has not yet been undertaken. Here, we investigate the relatedness of diatom lineages in Siberian lakes along environmental gradients (i.e. across treeline transects), over geographic distance and through time (i.e. the last 7000 years) using modern and ancient sedimentary DNA. Our results indicate that closely-related Staurosira lineages occur in similar environments and less-related lineages in dissimilar environments, in our case different vegetation and co-varying climatic and limnic variables across treeline transects. Thus our study reveals that environmental conditions rather than geographic distance is reflected by diatom-relatedness patterns in space and time. We tentatively speculate that the detected relatedness pattern in Staurosira across the treeline could be a result of adaptation to diverse environmental conditions across the arctic boreal treeline, however, a geographically-driven divergence and subsequent repopulation of ecologically different habitats might also be a potential explanation for the observed pattern.

  8. Perturbation induced changes in substrate use by the blue mussel, Mytilus edulis, in sedimentary systems

    NASA Astrophysics Data System (ADS)

    wa Kangeri, Arno K.; Jansen, Jeroen M.; Barkman, Barbara R.; Donker, Jasper J. A.; Joppe, Daniel J.; Dankers, Norbert M. J. A.

    2014-01-01

    For sessile benthic marine organisms adhesion to a stable substrate is important for survival. Sedimentary systems, however, generally lack stable surfaces. How sessile species like the mussel, Mytilus edulis, are able to achieve stability in unstable sediments is not fully understood. An intertidal mussel bed in the tidal flats in the Western portion of the Dutch Wadden Sea was selected to investigate adhesion behavior of M. edulis. Sampling was conducted along a hydrodynamic gradient along the Front-edge, Center and Back-edge of a mussel bed. Mussels along the bed edges were characterized by adhesion to fine shell debris and high numbers of byssus threads. Mussels in the center of the bed were characterized by adhesion to shells of living conspecifics and relatively low numbers of byssus threads. An experimental investigation to isolate the role of perturbation on adhesion strategies was carried out under laboratory conditions. Experimental results show that under perturbed conditions mussels developed increased numbers of byssus threads relative to mussels left unperturbed. Additionally, mussels subjected to perturbation preferentially adhered more frequently to fine shell debris while unperturbed mussels adhered more frequently to conspecifics. Results show that differentiation in adhesion strategy is driven by physical perturbation and mediated by bed density. The results also suggest that adhesion by mussels in a sedimentary environment is a selective process in which larger shell fragments and shells of conspecifics are the preferred substrate.

  9. Deep Subsurface Biodegradation of Sedimentary Organic Matter in a Methane-Rich Shale Gas Reservoir

    NASA Astrophysics Data System (ADS)

    Formolo, M. J.; Petsch, S.; Salacup, J.; Waldron, P.; Martini, A.; Nusslein, K.

    2006-12-01

    Extensive, sustained subsurface microbial activity in the Antrim Shale (Late Devonian, Michigan Basin, USA) has led to the accumulation of an important unconventional natural gas resource, from which is produced ~14 million m3 of methane per day. Both geochemical and molecular evidence supports a community comprising diverse methanogens, fermentative microorganisms, and little else. The diversity of methanogens is strongly associated with a sharp gradient in formation water salinity spanning 10-4000 mM Cl-1. Analysis of hydrocarbon biomarkers within the Antrim reveal patterns of degradation that are directly associated with zones of active methanogenesis, with marked differences observed between methane- producing and non-producing sections of the formation. Maturity and source indicators show that these patterns do not result from varying degrees of thermal maturity or source inputs across the Basin, but instead demonstrate that biodegradation is confined solely to regions of the Basin exhibiting extensive methanogenesis. Calculated biodegradation indices provide evidence for nearly quantitative loss of saturated hydrocarbons, specifically n-alkanes and acyclic isoprenoids, during biodegradation associated with methanogenesis. These results are the first to document deep subsurface ancient sedimentary organic matter biodegradation associated with the formation of economic microbial gas reserves within low permeability, thermally-immature source rocks. As such, the results provide insight into microbial activity in the deep subsurface, specifically the role that methanogen-dominated communities may play in carbon-rich, electron acceptor-poor sedimentary basins.

  10. Deep injection of waste water in the Western Canada sedimentary basin.

    PubMed

    Ferguson, Grant

    2015-01-01

    Injection of wastes into the deep subsurface has become a contentious issue, particularly in emerging regions of oil and gas production. Experience in other regions suggests that injection is an effective waste management practice and that widespread environmental damage is unlikely. Over the past several decades, 23 km(3) of water has been injected into the Western Canada Sedimentary Basin (WCSB). The oil and gas industry has injected most of this water but large amounts of injection are associated with mining activities. The amount of water injected into this basin during the past century is 2 to 3 orders magnitude greater than natural recharge to deep formations in the WCSB. Despite this large-scale disturbance to the hydrogeological system, there have been few documented cases of environmental problems related to injection wells. Deep injection of waste appears to be a low risk activity based on this experience but monitoring efforts are insufficient to make definitive statements. Serious uncharacterized legacy issues could be present. Initiating more comprehensive monitoring and research programs on the effects of injection in the WCSB could provide insight into the risks associated with injection in less developed sedimentary basins.

  11. Interpretation of K-Ar dates of illitic clays from sedimentary rocks aided by modeling

    USGS Publications Warehouse

    Srodon, J.; Clauer, Norbert; Eberl, D.D.D.

    2002-01-01

    K-Ar dates of illitic clays from sedimentary rocks may contain "mixed ages," i.e., may have ages that are intermediate between the ages of end-member events. Two phenomena that may cause mixed ages are: (1) long-lasting reaction during the burial illitization of smectite: and (2) physical mixing of detrital and diagenetic components. The first phenomenon was investigated by simulation of illitization reactions using a nucleation and growth mechanism. These calculations indicate that values for mixed ages are related to burial history: for an equivalent length of reaction time, fast burial followed by slow burial produces much older mixed ages than slow burial followed by fast. The type of reaction that occured in a rock can be determined from the distribution of ages with respect to the thickness of illite crystals. Dating of artificial mixtures confirms a non-linear relation between mixed ages and the proportions of the components. Vertical variation of K-Ar age dates from Gulf Coast shales can be modeled by assuming diagenetic illitization that overprints a subtle vertical trend (presumably of sedimentary origin) in detrital mineral content.

  12. Searching for tsunamis evidences on the Algarve (Southern Portugal) continental shelf sedimentary record

    NASA Astrophysics Data System (ADS)

    Drago, Teresa; Silva, Pedro; Lopes, Ana; Magalhães, Vitor; Roque, Cristina; Rodrigues, Ana Isabel; Noiva, João; Terrinha, Pedro; Mena, Anxo; Francés, Guillermo; Kopf, Achim; Völker, David; Omira, Rachid; Baptista, Maria Ana

    2016-04-01

    Tsunami hazard assessment is important in order to prevent and/or minimize its effects, which is only possible if a complete and long record dataset of past events is available, allowing the estimation of their recurrence intervals. The knowledge of past tsunami events are based on instrumental, historical and geological records. Although instrumental and historical records are reliable sources they are limited in time. Geological records can give a much more extended reconstruction overview of thousand years, which can provide a good estimation of tsunami return periods. Most of the existing studies have been conducted onshore and only a few were based on offshore sedimentary record. These last ones, have the advantage to provide a more continuous and almost undisturbed records but the identification of tsunami sediments in marine environment require a multi-proxy approach in order to better identify the allochtonous layers/deposits and to differentiate them from storm deposits. In the context of ASTARTE project (FP7), five gravity and piston cores on the southern Portuguese continental shelf collected in 2008 and 2014 were studied. The methodology included XRF, MSCL, sedimentological and magnetic analyses. Preliminary results show some identifiable layers that may related with allochthonous sedimentary material, compatible with a genesis resulting from tsunami backwash sediment transport and deposition. Acknowledgments - Publication supported by project FCT UID/GEO/50019/2013 - Instituto Dom Luiz.

  13. A 60-year sedimentary record of natural and anthropogenic impacts on Lake Chenghai, China.

    PubMed

    Zan, Fengyu; Huo, Shouliang; Xi, Beidou; Zhang, Jingtian; Liao, Haiqing; Wang, Yue; Yeager, Kevin M

    2012-01-01

    Recent sediments from Lake Chenghai, China, were investigated at high temporal resolution to trace both natural and anthropogenic effects on the lake using total organic carbon (TOC), total nitrogen (TN), total phosphorus (TP), organic phosphorus (Po), inorganic phosphorus (Pi) and organic carbon and nitrogen stable isotopes (delta13Corg and delta15N) in a 137Cs-dated sediment core. The results indicated that the sedimentary record covers the last 60 years, during which the lake had undergone apparent changes in nutrient sources and productivity in response to nutrient loading. Prior to the late 1980s, the nutrient contents in sediments mainly originated from algae and lake productivity was relatively stable. Since the late 1980s, increasing TOC, TN and TP concentrations together with the change of delta13Corg and delta15N suggested anthropogenic perturbations in nutrient loading and lake productivity. Endogenic nutrients derived from algae and anthropogenic inputs were two important sources of sedimentary nutrients. The anthropogenic nutrients mainly originated from the discharge of industrial wastewater and artificial cultivation of Spirulina after the middle 1980s, and domestic wastewater discharged from Yongsheng County since 1993.

  14. Hydraulic characteristics of the Maastrichtian sedimentary rocks of the southeastern Bida Basin, central Nigeria

    NASA Astrophysics Data System (ADS)

    Vrbka, Petr; Ojo, Olusola Johnson; Gebhardt, Holler

    1999-12-01

    A set of outcrop samples from the Lokoja and Patti Formations of the southern Bida Basin (Nigeria) was examined for grain size distribution, sedimentary and hydraulic characteristics. Most of the samples are well-sorted with an uniformity coefficient (U) ranging between 1.3 and 6.3. The mean effective grain diameter (d 10) is in the order of 0.11 mm, the mean value of d 90 was determined as 0.66 mm (both geometric mean) and the median grain size (d 50) as 0.23 mm. Based on these values, the sedimentary sequence can be described as 'fine to medium sized sand', having minor amounts of either silt, or coarse sand and some gravel. The total porosity of the samples was determined by laboratory methods to be in the range of 9-29%. The hydraulic conductivity (K) was determined according to Hazen.and Beyer, and by Shepherd's formula, the last resulting in a geometric mean of 3.3 m d -1 or 3.3 darcy. The results are used to estimate local groundwater potential. The entire pore space (potential groundwater reservoir) for the area under study is estimated to be in the order of 290-430 km 3. Because of higher hydraulic conductivities, it is recommended that the Lokoja Formation is concentrated on as a target for groundwater exploration.

  15. Structural geology of Amazonian-aged layered sedimentary deposits in southwest Candor Chasma, Mars

    NASA Astrophysics Data System (ADS)

    Okubo, Chris H.

    2010-05-01

    The structural geology of an outcropping of layered sedimentary deposits in southwest Candor Chasma is mapped using two adjacent high-resolution (1 m/pixel) HiRISE digital elevation models and orthoimagery. Analysis of these structural data yields new insight into the depositional and deformational history of these deposits. Bedding in non-deformed areas generally dips toward the center of west Candor Chasma, suggesting that these deposits are basin-filling sediments. Numerous kilometer-scale faults and folds characterize the deformation here. Normal faults of the requisite orientation and length for chasma-related faulting are not observed, indicating that the local sediments accumulated after chasma formation had largely ceased in this area. The cause of the observed deformation is attributed to landsliding within these sedimentary deposits. Observed crosscutting relationships indicate that a population of sub-vertical joints are the youngest deformational structures in the area. The distribution of strain amongst these joints, and an apparently youthful infill of sediment, suggests that these fractures have been active in the recent past. The source of the driving stress acting on these joints has yet to be fully constrained, but the joint orientations are consistent with minor subsidence within west Candor Chasma.

  16. Excavatability Assessment of Weathered Sedimentary Rock Mass Using Seismic Velocity Method

    NASA Astrophysics Data System (ADS)

    Bin Mohamad, Edy Tonnizam; Saad, Rosli; Noor, Muhazian Md; Isa, Mohamed Fauzi Bin Md.; Mazlan, Ain Naadia

    2010-12-01

    Seismic refraction method is one of the most popular methods in assessing surface excavation. The main objective of the seismic data acquisition is to delineate the subsurface into velocity profiles as different velocity can be correlated to identify different materials. The physical principal used for the determination of excavatability is that seismic waves travel faster through denser material as compared to less consolidated material. In general, a lower velocity indicates material that is soft and a higher velocity indicates more difficult to be excavated. However, a few researchers have noted that seismic velocity method alone does not correlate well with the excavatability of the material. In this study, a seismic velocity method was used in Nusajaya, Johor to assess the accuracy of this seismic velocity method with excavatability of the weathered sedimentary rock mass. A direct ripping run by monitoring the actual production of ripping has been employed at later stage and compared to the ripper manufacturer's recommendation. This paper presents the findings of the seismic velocity tests in weathered sedimentary area. The reliability of using this method with the actual rippability trials is also presented.

  17. Crustal thickening and clay: Controls on O isotope variation in global magmatism and siliciclastic sedimentary rocks

    NASA Astrophysics Data System (ADS)

    Payne, Justin L.; Hand, Martin; Pearson, Norman J.; Barovich, Karin M.; McInerney, David J.

    2015-02-01

    New compilations of global O isotope data from zircon and siliciclastic sedimentary rocks highlight an increasing range in δ18O values in both systems since the late Archean. This is consistent with an increased clay component in sedimentary rocks and subsequent incorporation into igneous rocks. Each of these factors can arguably be achieved by increased crustal thickening in the late Archean resulting in greater burial and melting of supracrustal rocks and increased chemical weathering and recycling of upper crustal rocks. Despite the suggested change in tectonic regimes in the late Archean, stochastic modelling in this study demonstrates that δ18O data do not provide evidence for a secular decrease in the proportion of mantle-derived magmas in granitoid rocks. Instead, best-fit models indicate that juvenile input and reworking of supracrustal material vary with respect to the short term (100-200 Myr) tectonic cycles preserved in the continental crust. Hence, major step changes in global tectonic regimes in the post-Hadean, such as the initiation of subduction in the mid- to late Archean, are not supported by global zircon O isotope datasets and instead minor, progressive changes are indicated for Earth's tectonic regimes.

  18. Classification Scheme for Diverse Sedimentary and Igneous Rocks Encountered by MSL in Gale Crater

    NASA Technical Reports Server (NTRS)

    Schmidt, M. E.; Mangold, N.; Fisk, M.; Forni, O.; McLennan, S.; Ming, D. W.; Sumner, D.; Sautter, V.; Williams, A. J.; Gellert, R.

    2015-01-01

    The Curiosity Rover landed in a lithologically and geochemically diverse region of Mars. We present a recommended rock classification framework based on terrestrial schemes, and adapted for the imaging and analytical capabilities of MSL as well as for rock types distinctive to Mars (e.g., high Fe sediments). After interpreting rock origin from textures, i.e., sedimentary (clastic, bedded), igneous (porphyritic, glassy), or unknown, the overall classification procedure (Fig 1) involves: (1) the characterization of rock type according to grain size and texture; (2) the assignment of geochemical modifiers according to Figs 3 and 4; and if applicable, in depth study of (3) mineralogy and (4) geologic/stratigraphic context. Sedimentary rock types are assigned by measuring grains in the best available resolution image (Table 1) and classifying according to the coarsest resolvable grains as conglomerate/breccia, (coarse, medium, or fine) sandstone, silt-stone, or mudstone. If grains are not resolvable in MAHLI images, grains in the rock are assumed to be silt sized or smaller than surface dust particles. Rocks with low color contrast contrast between grains (e.g., Dismal Lakes, sol 304) are classified according to minimum size of apparent grains from surface roughness or shadows outlining apparent grains. Igneous rocks are described as intrusive or extrusive depending on crystal size and fabric. Igneous textures may be described as granular, porphyritic, phaneritic, aphyric, or glassy depending on crystal size. Further descriptors may include terms such as vesicular or cumulate textures.

  19. Distribution and sedimentary characteristics of tsunami deposits along the Cascadia margin of western North America

    USGS Publications Warehouse

    Peters, R.; Jaffe, B.; Gelfenbaum, G.

    2007-01-01

    Tsunami deposits have been found at more than 60 sites along the Cascadia margin of Western North America, and here we review and synthesize their distribution and sedimentary characteristics based on the published record. Cascadia tsunami deposits are best preserved, and most easily identified, in low-energy coastal environments such as tidal marshes, back-barrier marshes and coastal lakes where they occur as anomalous layers of sand within peat and mud. They extend up to a kilometer inland in open coastal settings and several kilometers up river valleys. They are distinguished from other sediments by a combination of sedimentary character and stratigraphic context. Recurrence intervals range from 300-1000??years with an average of 500-600??years. The tsunami deposits have been used to help evaluate and mitigate tsunami hazards in Cascadia. They show that the Cascadia subduction zone is prone to great earthquakes that generate large tsunamis. The inclusion of tsunami deposits on inundation maps, used in conjunction with results from inundation models, allows a more accurate assessment of areas subject to tsunami inundation. The application of sediment transport models can help estimate tsunami flow velocity and wave height, parameters which are necessary to help establish evacuation routes and plan development in tsunami prone areas. ?? 2007.

  20. Rock property measurements and analysis of selected igneous, sedimentary, and metamorphic rocks from worldwide localities

    USGS Publications Warehouse

    Johnson, Gordon R.

    1983-01-01

    Dry bulk density and grain density measurements were made on 182 samples of igneous, sedimentary, and metamorphic rocks from various world-wide localities. Total porosity values and both water-accessible and helium-accessible porosities were calculated from the density data. Magnetic susceptibility measurements were made on the solid samples and permeability and streaming potentials were concurrently measured on most samples. Dry bulk densities obtained using two methods of volume determination, namely direct measurement and Archlmedes principle, were nearly equivalent for most samples. Grain densities obtained on powdered samples were typically greater than grain densities obtained on solid samples, but differences were usually small. Sedimentary rocks had the highest percentage of occluded porosity per rock volume whereas metamorphic rocks had the highest percentage of occluded porosity per total porosity. There was no apparent direct relationship between permeability and streaming potential for most samples, although there were indications of such a relationship in the rock group consisting of granites, aplites, and syenites. Most rock types or groups of similar rock types of low permeability had, when averaged, comparable levels of streaming potential per unit of permeability. Three calcite samples had negative streaming potentials.

  1. Modern Pearl River Delta and Permian Huainan coalfield, China: A comparative sedimentary facies study

    USGS Publications Warehouse

    Suping, P.; Flores, R.M.

    1996-01-01

    Sedimentary facies types of the Pleistocene deposits of the Modern Pearl River Delta in Guangdong Province, China and Permian Member D deposits in Huainan coalfield in Anhui Province are exemplified by depositional facies of anastomosing fluvial systems. In both study areas, sand/sandstone and mud/mudstone-dominated facies types formed in diverging and converging, coeval fluvial channels laterally juxtaposed with floodplains containing ponds, lakes, and topogenous mires. The mires accumulated thin to thick peat/coal deposits that vary in vertical and lateral distribution between the two study areas. This difference is probably due to attendant sedimentary processes that affected the floodplain environments. The ancestral floodplains of the Modern Pearl River Del