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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. 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

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. Global sedimentary geology program

    SciTech Connect

    Ginsburg, R.N.; Clifton, H.E.; Weimer, R.J.

    1986-07-01

    The Society of Economic Paleontologists and Mineralogists, in collaboration with the International Association of Sedimentologists and the International Union of Geological Sciences Committee on Sedimentology, is developing a new international study under the provisional title of Global Sedimentary Geology Program (GSGP). Initially, three research themes are being considered: (1) event stratigraphy-the documentation of examples of mass extinctions, eustatic fluctuations in sea level, major episodes of volcanisms, and changes in ocean composition; (2) facies models in time and space-an expansion of the existing data base of examples of facies models (e.G., deltas, fluvial deposits, and submarine fans) and global-scale study of the persistence of facies at various times in geologic history; and (3) sedimentary indices of paleogeography and tectonics-the use of depositional facies and faunas in paleogeography and in assessing the timing, locus, and characteristics of tectonism. Plans are being developed to organize pilot projects in each of these themes.

  10. 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

  11. 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.

  12. 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

  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. 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.

  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. 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.

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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. PMID:24566296

  1. Sedimentary rocks of early Mars.

    PubMed

    Malin, M C; Edgett, K S

    2000-12-01

    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.

  2. 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.

  3. 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.

  4. 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.

  5. Sedimentary pyrite formation: An update

    NASA Astrophysics Data System (ADS)

    Berner, Robert A.

    1984-04-01

    Sedimentary pyrite formation during early diagenesis is a major process for controlling the oxygen level of the atmosphere and the sulfate concentration in seawater over geologic time. The amount of pyrite that may form in a sediment is limited by the rates of supply of decomposable organic matter, dissolved sulfate, and reactive detrital iron minerals. Organic matter appears to be the major control on pyrite formation in normal (non-euxinic) terrigenous marine sediments where dissolved sulfate and iron minerals are abundant. By contrast, pyrite formation in non-marine, freshwater sediments is severely limited by low concentrations of sulfate and this characteristic can be used to distinguish ancient organic-rich fresh water shales from marine shales. Under marine euxinic conditions sufficient H 2S is produced that the dominant control on pyrite formation is the availability of reactive iron minerals. Calculations, based on a sulfur isotope model, indicate that over Phanerozoic time the worldwide average organic carbon-to-pyrite sulfur ratio of sedimentary rocks has varied considerably. High C/S ratios during Permo-Carboniferous time can be explained by a shift of major organic deposition from the oceans to the land which resulted in the formation of vast coal swamps at that time. Low C/S ratios, compared to today, during the early Paleozoic can be explained in terms of a greater abundance of euxinic basins combined with deposition of a more reactive type of organic matter in the remaining oxygenated portions of the ocean. The latter could have been due to lower oceanic oxygen levels and/or a lack of transportation of refractory terrestrial organic matter to the marine environment due to the absence of vascular land plants at that time.

  6. 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

  7. Sedimentary facies in submarine canyons

    NASA Astrophysics Data System (ADS)

    Sumner, E.; Paull, C. K.; Gwiazda, R.; Anderson, K.; Lundsten, E. M.; McGann, M.

    2013-12-01

    Submarine canyons are the major conduits by which sediment, pollutants and nutrients are transported from the continental shelf out into the deep sea. The sedimentary facies within these canyons are remarkably poorly understood because it has proven difficult to accurately sample these heterogeneous and bathymetrically complex environments using traditional ship-based coring techniques. This study exploits a suite of over 100 precisely located vibracores collected using remotely operated vehicles in ten canyons along the northern Californian margin, enabling better understanding of the facies that exist within submarine canyons, their distribution, and the processes responsible for their formation. The dataset reveals three major facies types within the submarine canyons: extremely poorly sorted, coarse-grained sands and gravels with complex and indistinct internal grading patterns and abundant floating clasts; classical normally graded thin bedded turbidites; and a variety of fine-grained muddy deposits. Not all facies are observed within individual canyons, in particular coarse-grained deposits occur exclusively in canyons where the canyon head cuts up to the modern day beach, whereas finer grained deposits have a more complex distribution that relates to processes of sediment redistribution on the shelf. Pairs of cores collected within 30 meters elevation of one another reveal that the coarse-grained chaotic deposits are restricted to the basal canyon floor, with finer-grained deposits at higher elevations on the canyon walls. The remarkable heterogeneity of the facies within these sediment cores illustrate that distinctive processes operate locally within the canyon. In the authors' experience the canyon floor facies represent an unusual facies rarely observed in ancient outcrops, which potentially results from the poor preservation of ancient coarse-grained canyon deposits in the geological record.

  8. Sedimentary basins and crustal thickening

    NASA Astrophysics Data System (ADS)

    Cobbold, P. R.; Davy, P.; Gapais, D.; Rossello, E. A.; Sadybakasov, E.; Thomas, J. C.; Tondji Biyo, J. J.; de Urreiztieta, M.

    1993-07-01

    We consider the development of sedimentary basins in a tectonic context dominated by horizontal shortening and vertical thickening of the crust. Well-known examples are foreland basins; others are ramp basins and buckle basins. We have reproduced various styles of compressional basins in experiments, properly scaled for gravity. A multilayered model lithosphere, with brittle and ductile layers, floats on a model asthenosphere. A computer-driven piston provides shortening and thickening, synchronous with erosion and sedimentation. After a first stage of lithospheric buckling, thrust faults appear, mainly at inflection points. Slip on an isolated reverse fault is accompanied by flexure. Footwall flexure results in a foreland basin and becomes accentuated by sedimentation. Hangingwall flexure is less marked, but may become accentuated by erosion. Motion on a fault leads to hangingwall collapse at the surface. Either footwall sedimentation or hangingwall erosion tends to prolong the active life of a reverse fault. Slip on any pair of closely spaced reverse faults of opposite vergence results in a ramp basin. Simultaneous slip produces a symmetric ramp basin, whereas alternating slip results in a butterfly-shaped basin, with superposed foredeeps. Some well-developed ramp basins become pushed down, until bounding faults meet at the surface and the basin disappears from view. At this stage, the basin depth is equivalent to 15 km or more. Slip on any pair of widely spaced reverse faults of opposite vergence results in a pronounced central anticline, between two distinct foredeeps. In Central Asia and in Western Europe, Cenozoic crustal thickening is due to continental collision. For Central Asia (Western China, Kyrgyzstan, Uzbekistan, Tajikistan), we have compiled a regional structure-contour map on the base of the Tertiary, as well as 4 regional sections. Foreland basins and ramp basins are numerous and associated with Cenozoic thrusts. Large basins (Tarim, Junggar

  9. 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

  10. Geology, exploration status of Uruguay's sedimentary basins

    SciTech Connect

    Goso, C.; Santa Ana, H. de )

    1994-02-07

    This article attempts to present the geological characteristics and tectonic and sedimentary evolution of Uruguayan basins and the extent to which they have been explored. Uruguay is on the Atlantic coast of South America. The country covers about 318,000 sq km, including offshore and onshore territories corresponding to more than 65% of the various sedimentary basins. Four basins underlie the country: the Norte basin, the Santa Lucia basin, the offshore Punta del Este basin, and the offshore-onshore Pelotas-Merin basin. The Norte basin is a Paleozoic basin while the others are Mesozoic basins. Each basin has been explored to a different extent, as this paper explains.

  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. Tectonic and sedimentary evolution of Bransfield Basin, Antarctica

    SciTech Connect

    Jeffers, J.D.; Thomas, M.A.; Anderson, J.B.

    1988-01-01

    The Bransfield basin is the youngest and best developed of a series of extensional marginal basins on the Pacific margin of the Antarctic Peninsular. Marine geophysical data collected over five seasons show that the back arc is segmented laterally into three subbasins separated by transform zones. These subbasins differ in width, depth, structural style, and seisimicity and are correlated with three different age segments of subducted sea floor. The distribution of principal sedimentary environments, identified from high-resolution seismic reflection data, and their associated lithofacies, seen in piston cores and surface sediment samples, is controlled largely by the tectonic segmentation of the basins. Terrigenous sediments prograde into the basin from the continent side, whereas sediment gravity-flow processes deliver volcaniclastic material from the arc to slope-base aprons and to fan lobes at the outlets of fiords. Organic-rich muds fill the deep basin; their proximity to submarine volcanic centers produces thermogenic hydrocarbons. Understanding the recent tectonic and sedimentary evolution of the Bransfield basin may help refine interpretations of the older deformed marginal basin sequences of southern South America, the Scotia Arc, and the Antarctic Peninsula.

  13. 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. PMID:22326688

  14. Paleozoic sedimentary rocks in oaxaca, Mexico.

    PubMed

    Pantoja-Alor, J; Robison, R A

    1967-09-01

    Fossiliferous Cambrian, Ordovician, Mississippian, and Pennsylvanian rocks, never before found in southern Mexico, have been discovered in the Nochixtlán region. Superjacent unfossiliferous sedimentary rocks may be Permian in age. Early Paleozoic and late Paleozoic intervals of marine sedimentation were bounded by intervals of positive tectonism and erosion.

  15. 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.

  16. 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

  17. 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

  18. 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.

  19. Rapid lithification masks the Venus sedimentary cycle

    NASA Astrophysics Data System (ADS)

    Ghail, R.

    2015-10-01

    Venera lander data are usually assumed to indicate basaltic lavas but a significant fraction of the rock material must be volatiles, such as sulphur, implying at least strongly weathered basalts. The lander images most closely resemble sedimentary material, with layered strata (which may be pyroclastic in origin)that are sometimes broken into cobbles and fine grained sediment. The Magellan SAR was relatively insensitive to loose fine-grained material under Venus surface conditions but the reprocessed data reveal a range of weathering processes, particularly at higher elevations, and mass wasting of steep slopes. Mean wind speeds are strongly altitude dependent and are able to erode and transport material throughout the highland regions. In some areas, this material is deposited on adjacent plains where, under the extreme Venus surface conditions, lithification is an apparently rapid process. Thus the largely featureless plains may not be igneous at all but sedimentary in origin. The settling out and lithification of sedimentary material is consistent with observed crater degradation, in which low-lying crater floors are infilled first.

  20. 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.

  1. 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.

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

    NASA Astrophysics Data System (ADS)

    Zech, M.; Kreutzer, S.; Goslar, T.; Meszner, S.; Krause, T.; Faust, D.; Fuchs, M.

    2012-07-01

    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. 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 cal BP 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 cal BP, 22.1 ± 0.7 kyr cal BP and 29.8 ± 1.4 kyr cal BP) 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 (current, modern, 3 kyr, 6 kyr and 9 kyr). Accordingly, current and modern 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.

  4. Martian Sedimentary Basins and Central Mound Formation

    NASA Astrophysics Data System (ADS)

    Bennett, K. A.; Bell, J. F., III

    2014-12-01

    Central mounds on Mars are observed as sedimentary deposits within crater interiors, but the specific processes responsible for their formation and subsequent modification are still debated. The deposits are hypothesized to have been created by either subaerial or subaqueous processes through one of two general formation mechanisms. The prevailing hypothesis suggests that after their craters were formed, sediment filled the entire crater and was later eroded into the morphologies we observe today. Alternatively, the sediment could have been deposited as the features we observe today without any significant erosion contributing to their mound shape. We conducted a survey of central mounds that occur within craters larger than 25 km in diameter located between ± 60° latitude on Mars. We use mound locations, mound offsets within their host craters, and mound heights to address various mound formation hypotheses. The results of this survey support the hypothesis that mound sediment once filled the entire host crater and was later eroded into the features we observe today. We propose that large Martian impact craters act as simplistic sedimentary basins. These basins "catch" any sediment that is being transported through the region. Any geologic process that involves transport of material (airfall dust, explosive volcanism, impact ejecta, etc.) could have contributed to the growth of this sediment fill, although the dominant process could vary based on location. During this depositional phase, several processes (ice/frost, water, etc.) could have cemented the material; then, at some point, the environment changed from depositional to erosional, leading to the formation of isolated mounds of sediment within these craters. Our study reveals that most mounds are offset from the center of their host crater in the same direction as the regional winds. For example, the mounds in Arabia Terra are offset towards the western portion of their craters. This observation is

  5. Prediction of hydrocarbons in sedimentary basins

    USGS Publications Warehouse

    Harff, J.E.; Davis, J.C.; Eiserbeck, W.

    1993-01-01

    To estimate the undiscovered hydrocarbon potential of sedimentary basins, quantitative play assessments specific for each location in a region may be obtained using geostatistical methods combined with the theory of classification of geological objects, a methodology referred to as regionalization. The technique relies on process modeling and measured borehole data as well as probabilistic methods to exploit the relationship between geology (the "predictor") and known hydrocarbon productivity (the "target") to define prospective stratigraphic intervals within a basin. It is demonstrated in case studies from the oil-producing region of the western Kansas Pennsylvanian Shelf and the gas-bearing Rotliegend sediments of the Northeast German Basin. ?? 1993 International Association for Mathematical Geology.

  6. Phanerozoic cycles of sedimentary carbon and sulfur

    PubMed Central

    Garrels, Robert M.; Lerman, Abraham

    1981-01-01

    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 CO2 to SO4 from the Cambrian to the Permian Period was several times the Recent free oxygen content of the atmosphere. PMID:16593066

  7. 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.

  8. Tunnel boring machine performance in sedimentary rock

    SciTech Connect

    Nelson, P.

    1983-01-01

    Full-face tunnel boring machine (TBM) performance during the excavation of six tunnels is considered in terms of utilization, penetration rate, and cutter wear. Construction records for over 75,000 ft (22,860m) of tunnel in sedimentary rock are analyzed, and the results are used to investigate factors affecting TBM performance. Machine utilization is strongly affected by site specific conditions, including geology, construction planning, and contractor practice. The relative importance of each of 21 downtime causes is discussed, and recommendations are made for modifications in excavation system design which could help to reduce delays. Effects of machine operation rate were investigated. The interrelationship among penetration, thrust, and rolling force is analyzed with a three-dimensional model which provides a rational basis for explaining variations in cutter forces and penetration rate as a function of rock type. The most useful rock index for estimating TBM performance in sedimentary rock is shown to be a combination of Schmidt Hammer rebound and abrasion hardness. Variation in cutter wear is considered as a function of position on the cutterhead and the rock type being excavated. Rolling distances for center cutters are less sensitive to rock type than for other positions. A fracture mechanics approach, of use in modeling the process chip formation, is proposed. The use of fracture material properties for empirical prediction of TBM performance is reported. Recommendations are made for future work, and observations and records required for future performance evaluations are summarized.

  9. 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).

  10. 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.

  11. Archean sedimentary systems and crustal evolution

    NASA Technical Reports Server (NTRS)

    Lowe, D. R.

    1985-01-01

    Current knowledge of preserved Archean sedimentary rocks suggests that they accumulated in at least three major depositional settings. These are represented generally by sedimentary units: (1) in early Archean, pre-3.0 Ga old greenstone belts, (2) on late Archean sialic cratons, and (3) in late Archean, post-3.0 Ga old greenstone belts. Research suggests that the Archean was characterized by at least two distinctive and largely diachronous styles of crustal evolution. Thick, stable early Archean simatic platforms, perhaps analogous to modern oceanic islands formed over hot spots, underwent a single cycle of cratonization to form stable continental blocks in the early Archean. Later formed Archean continents show a two stage evolution. The initial stage is reflected in the existence of older sialic material, perhaps representing incompletely cratonized areas or microcontinents of as yet unknown origin. During the second stage, late Archean greenstone belts, perhaps analogous to modern magmatic arcs or back arc basins, developed upon or adjacent to these older sialic blocks. The formation of this generation of Archean continents was largely complete by the end of the Archean. These results suggest that Archean greenstone belts may represent a considerable range of sedimentological and tectonic settings.

  12. 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. PMID:16593066

  13. 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

  14. 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.

  15. 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

  16. Shallow sedimentary framework of Georges Bank

    USGS Publications Warehouse

    Lewis, R.S.; Sylwester, R.E.

    1976-01-01

    Two thousand nine hundred kilometers of minisparker data were collected on Georges Bank by the United States Geological Survey during October of 1975. Several sedimentary features have been observed in the data, The bank is recognized as a compound feature resulting from erosion of Tertiary coastal-plain strata followed by deposition of an extensive sediment wedge on the western flank of the cuesta. Marine planation (probably Late Pleistocene) truncated this bank morphology producing an erosion surface roughly paralleling the present sea floor. The truncated bank surface is blanketed by a veneer of complex Late Pleistocene drift which masks underlying features and is being reworked by modern processes. Present bank morphology is inferred-to be arather recent development. A proper understanding of the significance of complex bank sediments with respect to the potential geologic hazards of drilling or placement of bottom. supported structures necessitates a more detailed seismic reflection program, in conjunction with geotechnical analysis of core-samples.

  17. 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.

  18. 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%.

  19. 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.

  20. 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.

  1. The sedimentary supply of African sedimentary basins over the last 250 Ma

    NASA Astrophysics Data System (ADS)

    Rouby, Delphine; Guillocheau, Francois; Robin, Cecile; Helm, Catherine

    2010-05-01

    The African continent is bordered by passive margins and bears intracontinental basins preserving the terrigeneous sediment resulting from its erosion, and as such, recording the dynamics of its relief variation. Our objective is to bring new constraints on the uplift and erosion of the African continent over the last 250 Ma from the perspective of the stratigraphic architecture of its sedimentary basins. The novel aspect of our approach is to integrate the evolution of both the domains in erosion and in sedimentation (i.e. from the drainage divide of the domain in erosion down to the most distal deposits over the oceanic crust), and to review published data to quantify the terrigeneous supply eroded in the drainage area and preserved in the basins. One objective is to evaluate the conditions under which this simple approach, based on already published data, can be used to infer continental relief variations, the sedimentary archives of the domain in erosion being by definition scarce and denudation evaluation by thermochronology usually relying on hypotheses on past heat flows. We quantify the siliciclastic sedimentary volumes preserved in African basins correcting from porosity and in-situ (e.g. carbonate) production, with a particular attention to the determination of uncertainties resulting from parameters such as: velocity laws used to depth conversion of TWT data, biostratigraphic used for calibration in absolute ages, lithology assumed for porosity removal. We use two approaches with complementary spatial and temporal resolutions. (1) When data are available (e.g along the South African and Namibian Atlantic margins), we determine the long-term signal of sedimentary supply (x10 Ma) from 3D mass balance calculations comparing sedimentary volumes deduced from offshore isopach maps on one hand and erosion volumes deduced from the present day geometry of geomorphic markers and thermochronology data on the other hand. We show that our approach provide a good

  2. 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.

  3. 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 Ducks"; (5) "Inktomi and the…

  4. Hydrocarbons and magnetizations in sedimentary rocks

    SciTech Connect

    Frutt, D.; Elmore, R.D.; Engel, M.; Imbus, S.; Leach, M. )

    1991-03-01

    Hydrocarbons can have variable effects on the magnetic properties of sedimentary rocks. Understanding the nature of these effects has implications for dating hydrocarbon migration and magnetic prospecting. Previous work on hydrocarbon migration and magnetic prospecting. Previous work on hydrocarbon saturated calcite speleothems has established that hydrocarbons can create the chemical conditions that lead to precipitation of magnetite and acquisition of an associated chemical magnetization. The mechanism(s) of magnetite authigenesis, however, is unresolved. Geochemical studies of the speleotherms provide some information on the nature of the relationship. The level of biodegradation is variable, and samples with high magnetic intensities have, in general, lower apparent biodegradation levels than those with low magnetic intensities. These results suggest that biodegradation is not the only mechanism of magnetite precipitation. Although hydrocarbons can cause an increase in magnetization due to precipitation of magnetic phases in some rocks, in red beds there is an overall decrease in magnetization due to dissolution of hematite. For example, hydrocarbon migration into the Schoolhouse Member of the Maroon Formation (Pennsylvanian) in northwestern Colorado and the Rush Springs Formation (Permian) in Oklahoma caused dissolution of diagenetic hematite, bleaching, and a reduction in magnetic intensity. Magnetite and pyrrhotite are present in hydrocarbon-bearing sandstone and in some well cemented samples there are stable magnetizations that may be related to hydrocarbon migration.

  5. Sedimentary radioactive tracers and diffusive models.

    PubMed

    Carroll, J; Lerche, I

    2010-08-01

    This paper examines the underlying assumptions and consequences of applying a steady-state equation to sediment profiles of radioactive tracers in order to deconvolute sedimentation from bioturbation processes modelled as a diffusive type process. Several factors follow immediately from this investigation: (i) if the observed radioactive concentration increases with depth over any finite depth range then the proposed steady-state, constant flux equation is not applicable. Any increase in radioactive concentration with depth implies a negative mixing coefficient which is a physical impossibility; (ii) when the radioactive concentration systematically decreases with increasing sedimentary depth then solutions to the steady-state conservation equation exist only when either the constant solid state flux to the sediment surface is small enough so that a positive mixing coefficient results or when the mixing coefficient is small enough so that a positive flux results. If the radioactive concentration, porosity and/or density of the solid phase are such that the proposed equation is inappropriate (because no physically acceptable solution exists) then one must abandon the proposed steady-state equation. Further: if the flux of solid sediment to the sediment surface varies with time then, of course, a steady-state conservation equation is also inappropriate. Simple examples illustrate that the assumption of steady-state restricts the applicability of this modelling approach to a relatively small sub-set of expected situations in the real world.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Basement geology in the sedimentary basins of Nigeria

    NASA Astrophysics Data System (ADS)

    Avbovbo, Akpo A.

    1980-07-01

    In Nigeria, the dominant type of basement rock intersected by wells drilled for hydrocarbons, limestone, or water is granite. The three sedimentary basins in Nigeria are underlain by continental crust except in the Niger delta, where the basement rock is interpreted to be oceanic crust. Most of the wells that penetrated the basement are in the Eastern Dahomey embayment of western Nigeria. A maximum thickness of about 12,000 m of sedimentary rocks is attained in the offshore western Niger delta, but maximum thicknesses of sedimentary rocks are about 2,000 m in the Chad basin and only 500 m in the Sokoto embayment.

  12. A-D. Evolution of sedimentary basins

    SciTech Connect

    Not Available

    1988-01-01

    This book includes the first four chapters in a bulletin series on the evolution of the Appalachian Basin. Structural, tectonic, sedimentologic, and conodont color alteration studies are presented, and the implications of the results of these studies on hydrocarbon potential in the area are discussed.

  13. 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

  14. Holocene sedimentary environments in Smeerenburgfjorden, Spitsbergen

    NASA Astrophysics Data System (ADS)

    Heggdal Velle, Julie; Forwick, Matthias; Hass, H. Christian; Sverre Laberg, Jan; Vorren, Tore O.; Nielsen, Tove; Solheim, Anders

    2013-04-01

    Multi-proxy analyses of six sediment cores and analyses of swath bathymetry and chirp data were integrated to elucidate the Holocene sedimentary processes and palaeoenvironments in Smeerenburgfjorden, northwest Spitsbergen. Three basins separated by two sills define the present-day large-scale bathymetry. A transverse ridge in the innermost part of the fjord represents the Little Ice Age (LIA) maximum position of Smeerenburgbreen. Slide scars along the fjord sides and mass transport deposits in the basins indicate repeated mass wasting. Recessional moraines deposited during the last deglaciation suggest a mean annual retreat rate of 140 m/year. Another set of recessional moraines deposited between the maximum LIA position of Smeerenburgbreen and its present day terminus indicate a mean retreat rate of the ice front of ~87 m/year. Strong out-fjord decreasing trends in magnetic susceptibility and Fe-content indicate that these properties are related to material originating from the Hornemantoppen granite in the catchment of Smeerenburgbreen and are, thus, useful proxies for the reconstruction of the activity of the glacier. Relatively little ice rafting, most likely related to warmer surface water conditions, occurred between 8650 and 7350 cal. years BP. Ice rafting from both sea-ice and icebergs increased around 6200 cal. years BP and peaked at ~5200 cal. years BP, associated with a regional cooling. Smeerenburgbreen became more active around 2000 cal. years BP. It probably retreated during the Roman Warm Period (50 BC - AD 400) and advanced during the Dark Ages Cold Period (AD 400 - 800). From AD 1300 - 1500 (late Medieval Warm Period), ice rafting, sedimentation rates and productivity increased in the inner fjord. The Little Ice Age was characterised by reduced ice rafting, possibly linked to an increased sea-ice cover suppressing iceberg drift. An increase in Ice Rafted Debris (IRD) commencing around AD 1880 is suggested to represent the beginning of

  15. 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.

  16. 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.

  17. European Sedimentary Basins: Deciphering Palaeozoic intra-Pangea Wrench Faulting

    NASA Astrophysics Data System (ADS)

    Aubele, K.; Bachtadse, V.; Muttoni, G.; Ronchi, A.; Durand, M.

    2012-04-01

    Thick sections of sedimentary deposits act as tape recorders of the geomagnetic field over time and allow high resolution paleogeographic reconstructions. Over the past years, we were able to put together a considerable paleomagnetic data set collected from Early Permian and Mesozoic deposits in numerous sedimentary basins throughout Southwest Europe. This data set monitors relative block rotations about vertical axis in this area and thus provides convincing evidence for intra-Pangean wrench faulting in the Early Permian (~ 285-265 Ma). Here, we present previously processed data from Permian sedimentary sections from Southwest France and Sardinia together with data from the Saar-Nahe basin in West Germany. New data from the Permian/Triassic boundary from Sardinian sedimentary basins and data from Permian dyke swarms add further information to draw a more complete picture of the paleogeographic evolution of the Gondwana/Laurasia plate boundary and help to describe controversial intra-Pangean mobility and wrench faulting in the Early Permian.

  18. 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.

  19. 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.

  20. 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. PMID:17745908

  1. 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.

  2. Sedimentary phosphate method for estimating paleosalinities: a paleontological assumption.

    PubMed

    Guber, A L

    1969-11-01

    Paleosalinity values in certain rocks determined by the sedimentary phosphate method differ from salinity estimates based upon contained fossil assemblages, geochemical methods, and existing stratigraphic controls. Some anomalous values are related to the abundance of fossil organisms known to be concentrators of calcium phosphate. Because of the abundance and diversity of organisms which might introduce significant errors into paleosalinity estimates, the sedimentary phosphate method seemingly is of limited applicability.

  3. The post-Triassic sedimentary cover of Tunisia: Seismic sequences and structure

    NASA Astrophysics Data System (ADS)

    Bobier, C.; Viguier, C.; Chaari, A.; Chine, A.

    1991-09-01

    A series of geological cross sections based on data from the new geological map of Tunisia coupled with stratigraphic and structural studies indicate that a folded, post-Triassic sedimentary cover was separated from the basement by a decollement zone located in Triassic evaporitic deposits. Four depositional basins were formed during the Triassic and Liassic in an extensional regime, on a presumably thinned continental crust. Geological fieldwork, studies of metamorphic grade and gravimetric and magnetic surveys indicate that their depocentres shifted with time from basin to basin, finally resulting in today's Tellian and Tunisian troughs to the north, Gafsa Trough to the west of Gabes and the Tuniso-Libyan Trough to the east. Subsidence in the latter trough commenced at the end of the Cretaceous and is still continuing today. There are four well-defined seismic stratigraphic sequences comprising Mesozoic and Cenozoic sedimentary rocks, each with distinctive lithoseismic characteristics. We display the distribution and structure of these seismic sequences in a series of cross sections. In addition, we note that the regional tectonic style of Tunisia has been greatly influenced by a conjugate strike-slip fault system. The role of wrench faulting has been well-documented in the Kasserine and other areas by detailed structural studies.

  4. 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

  5. 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

  6. 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.

  7. 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

  8. Linking lithosphere deformation and sedimentary basin formation over multiple scales

    NASA Astrophysics Data System (ADS)

    Huismans, Ritske S.

    2016-04-01

    Here we focus on the relationships between tectonic deformation and sedimentary basin formation. Resolving the interaction and feedback between tectonic crust-lithosphere scale deformation and surface processes through erosion of elevated areas and formation of sedimentary basins over multiple scales has been a long-standing challenge. While forward process based models have been successful at showing that a feedback is expected between tectonic deformation and redistribution of mass at the earth's surface by erosion, transport, and deposition, demonstrating this coupling for natural systems has been an even greater challenge and is strongly debated. Observational constraints on crust-lithosphere deformation and surface processes are typically collected at highly varying spatial and temporal scales, while forward process based models are typically run at either very large lithosphere-mantle scale, or at the scale of the sedimentary basin making it difficult to investigate and explore the detailed interaction and feedback between these systems. Here I will report on recent advances in forward modelling linking crust-lithosphere deformation with surface processes over a large range of scales resolving tectonic plate scale deformation and sedimentary basin formation at stratigraphic scales. The forward numerical models indicate a linkage and interaction between the structural style of thick-skinned large-scale mountain belt and rift-passive margin formation, erosion-transport-deposition processes operating at the surface, and the thin-skinned deformation occurring in the associated sedimentary basins.

  9. 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.

  10. Linking lithosphere deformation and sedimentary basin formation over multiple scales

    NASA Astrophysics Data System (ADS)

    Huismans, Ritske S.

    2014-05-01

    In the spirit of Peter Ziegler we are interested in and explore the relationships between tectonic deformation and sedimentary basin formation. Resolving the interaction and feedback between tectonic crust-lithosphere scale deformation and surface processes through erosion of elevated areas and formation of sedimentary basins over multiple scales has been a long-standing challenge. While forward process based models have been successful at showing that a feedback is expected between tectonic deformation and redistribution of mass at the earth's surface by erosion, transport, and deposition, demonstrating this coupling for natural systems has been an even greater challenge and is strongly debated. Observational constraints on crust-lithosphere deformation and surface processes are typically collected at highly varying spatial and temporal scales, while forward process based models are typically run at either very large lithosphere-mantle scale, or at the scale of the sedimentary basin making it difficult to investigate and explore the detailed interaction and feedback between these systems. Here I will report on recent advances in forward modelling linking crust-lithosphere deformation with surface processes over a large range of scales resolving tectonic plate scale deformation and sedimentary basin formation at stratigraphic scales. The forward numerical models indicate a linkage and interaction between the structural style of thick-skinned large-scale mountain belt and rift-passive margin formation, erosion-transport-deposition processes operating at the surface, and the thin-skinned deformation occurring in the associated sedimentary basins.

  11. Magma Plumbing and Emplacement Mechanisms within Sedimentary Basins

    NASA Astrophysics Data System (ADS)

    Schofield, Nick; Magee, Craig; Holford, Simon; Jackson, Christopher

    2013-04-01

    In recent years our understanding of sub-volcanic magmatic plumbing systems has been revolutionised by the study of hydrocarbon industry 3D seismic reflection datasets from offshore sedimentary basins. In particular, 3D seismic reflection data has provided important insights into sheet intrusion geometry and emplacement mechanisms as well as linkages and magma flow between multiple intrusions within sill-complexes. However, even high-quality 3D seismic reflection datasets have a limit to what they can resolve; thus, to allow a better understanding of detailed emplacement mechanisms and to test the validity of subsurface-based interpretations, it is critical to bridge the resolution gap that exists between seismic and outcrop datasets. Magmatic sheet (sill) intrusions contribute significantly to the upper crustal magma transport network. The emplacement mechanism of the magmatic sheets controls the final geometry of the intrusions and the characteristics of host rock deformation. Previous observations have highlighted the preponderance of brittle structures (e.g. intrusive steps and broken brides) associated with shallow-level sheet intrusions. However, recent studies have suggested that non-brittle host rock behaviour also occurs, particularly related to the formation of magma fingers during shallow-level sill intrusion. Importantly, these structures can provide insights into emplacement style and magma flow directions. Here, we examine both brittle and non-brittle intrusion mechanisms and structures using both field- and 3D seismic-based observations from a series of widespread and variable magmatic systems. Non-brittle emplacement (i.e. magma finger and lobe development) appears to be primarily associated with viscous flow of the host rock during intrusion and is therefore intimately linked to the contemporaneous host rock rheology as well as magma dynamics. Purely brittle and non-brittle emplacement processes are found to be end members with many intrusions

  12. Three-dimensional simulations of ground motions in sedimentary basins

    USGS Publications Warehouse

    Frankel, Arthur

    1993-01-01

    This report describes work being done at the U.S. Geological Survey on 3-D simulations of earthquake ground motions in sedimentary basins. The ultimate goal of this research is to predict strong ground motions in sedimentary basins for expected large earthquakes. This report emphasizes the inadequacy of using flat-layered models for synthesizing ground motions in sedimentary basins. 2-D and 3-D simulations have demonstrated how the slope of the alluvium-bedrock interface can trap S-waves in the basins, producing prolonged surface wave trains. These large surface waves are not generated in 1-D flat layered models, which underestimate the duration and peak amplitude of shaking. We present results of 3-D simulations for the San Bernardino and Santa Clara valleys, California, for earthquakes on the San Andreas fault.

  13. 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.

  14. Sedimentary Framework of an Inner Continental Shelf Sand-Ridge System, West-Central Florida

    NASA Astrophysics Data System (ADS)

    Locker, S. D.; Hine, A. C.; Wright, A. K.; Duncan, D. S.

    2002-12-01

    The west-central Florida inner continental shelf is a dynamic environment subject to current flows on a variety of temporal and spatial scales. A site survey program, undertaken in support of the Office of Naval Research's Mine Burial prediction program, is focused on the sedimentary framework and sediment accumulation patterns in 10-18 meters water depth. Our specific goals are to image the shallow subsurface and to monitor changes in bedform distribution patterns that coincide with physical processes studies ongoing in the area. Methods of study include side-scan sonar imaging, boomer and chirp subbottom profiling, and sedimentary facies analysis using surface sediment sampling and vibracoring. A well-defined sand-ridge system was imaged, trending oblique to the west-Florida coastline. The side-scan clearly shows that there is extensive three-dimensional structure within these large-scale NW-SE trending sedimentary bedforms. The sand ridges commonly are approximately 1 km wide and 4-8 km in length. The characteristics of these ridges are distinctly different than the sand ridges in < 8 m water that we have previously studied. Ridges in the offshore area tend to be thicker, have a flatter morphology, and exhibit fewer smaller-scale sand waves. Sand-ridge thickness ranges 2-3 meters, and typically consists of fining upward medium to fine quartz sand facies with occasional centimeter-scale coarser-grained carbonate-rich intervals. Time series investigations tracking the shift in position of the sand ridge margins have found undetectable net annual movement. However significant resuspension and bedform development accompanies high-energy events such as winter cold front passage. Thus the large-scale bedforms (sand ridges) are in a state of dynamic equilibrium with the average annual hydrodynamic regime. Repeated field surveys will focus on monitoring small-scale sedimentological and stratal framework changes that will be integrated with the quantitative process

  15. 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.

  16. 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

  17. 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

  18. Lithologic mapping in a sedimentary environment using multipolarization SAR images

    NASA Technical Reports Server (NTRS)

    Evans, D. L.; Schenck, L. R.

    1985-01-01

    Multipolarization Synthetic Aperture Radar (SAR) data from the NASA/JPL aircraft SAR were used in conjunction with LANDSAT Thematic Mapper (TM), Thermal Infrared Multispectral Scanner (TIMS), and Airborne Imaging Spectrometer (AIS) data as part of a three-year research program to evaluate the utility of remote sensing measurements for analysis of sedimentary basins. The purpose of this research effort is to construct stratigraphic columns, map variations in the lithology, geometry, and structure of sedimentary rocks in the Wind River/Bighorn Basin area, Wyoming, and to integrate remote sensing data with conventional rain models of basin formation and evolution.

  19. Identification of thick sedimentary plains north of Hellas

    NASA Astrophysics Data System (ADS)

    Salese, Francesco; Mangold, Nicolas; Ansan, Veronique; Carter, John; Ody, Anouck; Poulet, François; Ori, Gian Gabriele

    2016-04-01

    Understanding the origin and timing of intercrater plains is crucial to understand the Martian history in relation with endogenic and/or exogenic cycles. Intercrater plains north of Hellas basin on Mars are thought to have hosted different sedimentary environments during the Late Noachian/Early Hesperian, and they offer a well-preserved insight into the regional geological history of Mars. Our new geologic mapping of the intercrater plains north of Hellas Basin is based on the rich data set from MRO and Mars Express and provides new insights into the region's geological history. These findings appear to constrain the interpretation of the nature and age of intercrater plains in this region, although we acknowledge that for example the source of the sedimentary deposits must be subject to further analysis. The northern part of Hellas basin displays topographically flat area, which was characterized during the Late Noachian by sedimentary deposition and later, in the Late Hesperian, by fissural volcanism. The map and crater retention ages enable us to interpret the geologic history of the region. The stratigraphically lower unit is represented by crustal outcrops. Across most of the region, the sedimentary unit covers the basement and is eroded into mesas, erosional windows and perched by fresh craters. Intercrater plains' sedimentary deposits north of Hellas display horizontal light-toned layered rich in Fe/Mg-phyllosilicates and local crossbedding stratification. The Noachian sedimentary deposits of the intercrater plains north of Hellas are locally covered by Hesperian lava flows, showing that intercrater plains are sedimentary and volcanic in origin. We found different erosional (regional and local) surfaces, at HiRISE scale inside sediments due to local erosional windows and at CTX scale we found two important regional erosional surfaces. The oldest between crustal outcrops and sediments, which is likely Middle Noachian in age and the youngest between sediments

  20. Sedimentary model for the giant Broken Hill Pb-Zn deposit, Australia

    NASA Astrophysics Data System (ADS)

    Wright, John V.; Haydon, Robert C.; McConachy, Geoff W.

    1987-07-01

    During the past 15 years there has been increasing acceptance of a volcanic exhalative origin for the giant 300-Mt Broken Hill Pb-Zn orebody. Supposedly, silicic pyroclastic rock types have been identified in the host-rock succession, and because of an association with basic volcanics (amphibolites), comparison is made with Phanerozoic continental rifts. The orebody has also been described as distal and deep water. We report that the so-called silicic volcanic rocks are all normal clastic sediments. The metasedimentary succession (more than 5 km thick) is interpreted as a series of major continental, fluvio-deltaic, progradational wedges interfingering with marine transgressive cycles, deposited in a gradually deepening basin. Pb-Zn mineralization is hosted by shallow-marine sands that later became reservoirs for the metal-bearing brines. Basin formation, stratigraphic architecture, and Pb-Zn mineralization can all be interpreted in terms of concepts understood from studies of the development of younger sedimentary basins. The inference is that Pb-Zn mineralization was generated by compactive expulsion of metal-bearing brines during accumulation of the sedimentary pile. *Request reprints from McConachy

  1. 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.

  2. 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

  3. 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)

  4. 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)

  5. 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

  6. Distinguishing different sedimentary facies in a deltaic system

    NASA Astrophysics Data System (ADS)

    Purkait, Barendra; Majumdar, Dipanjan Das

    2014-07-01

    An attempt has been made to differentiate sedimentary facies in a modern deltaic system by means of grain-size characteristics of the Ganga alluvial plain of West Bengal, India. Three main energy environments (marine, mixed and riverine) comprising the delta were considered. Sand samples were collected from rivers (both tidal and non-tidal), coastal dunes, beaches and tidal flats of the deltaic plain. The grain-size distribution patterns were compared with the two model distributions of log-normal and log-skew-Laplace. Different sedimentary facies were identified by discriminant functions. The analytical results indicate that the energy gradient of the different sedimentary facies of the deltaic system is well reflected by the grain-size characteristics of the individual facies. While critically analyzing the role of different textural parameters in discriminating the individual facies associations, it is observed that the mean size, alpha (slope of coarser fractions of Laplace model) and skewness have greater potential to distinguish different sedimentary facies of the deltaic system. The results of discriminant analysis might be applicable to paleo-environmental interpretation of a deltaic system by distinguishing the individual facies associations.

  7. 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.

  8. Influence of sedimentary environments on mechanical properties of clastic rocks

    NASA Astrophysics Data System (ADS)

    Meng, Zhaoping; Zhang, Jincai; Peng, Suping

    2006-10-01

    The sedimentary environments are the intrinsic factor controlling the mechanical properties of clastic rocks. Examining the relationship between rock sedimentary environments and rock mechanical properties gives a better understanding of rock deformation and failure mechanisms. In this study, more than 55 samples in coal measures were taken from seven different lithologic formations in eastern China. Using the optical microscope the sedimentary characteristics, such as components of clastic rocks and sizes of clastic grains were quantitatively tested and analyzed. The corresponding mechanical parameters were tested using the servo-controlled testing system. Different lithologic attributes in the sedimentary rocks sampled different stress-strain behaviors and failure characteristics under different confining pressures, mainly due to different compositions and textures. Results demonstrate that clastic rocks have the linear best-fit for Mohr-Coulomb failure criterion. The elastic moduli in clastic rocks are highly dependent upon confining pressures, unlike hard rocks. The envelope lines of the mechanical properties versus the contents of quartz, detritus of the grain diameter of more than 0.03 mm, and grain size in clastic rocks are given. The compressive strength or elastic modulus and the grain diameter have a non-monotonic relation and demonstrate the “grain-diameter softening” effect.

  9. 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.

  10. 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

  11. Depositional dynamics and self-organization in travertine sedimentary systems

    NASA Astrophysics Data System (ADS)

    Violante, C.; Marino, G.; Sammartino, S.

    2003-04-01

    Travertines are terrestrial sedimentary systems associated with flowing water oversaturated with respect to calcium carbonate. They form terraced wedge-shaped organogenic bodies, fan-shaped in plan view, with internal achitecture characterized by downslope elongated domal structures (mound), juxtaposed by onlap geometries. Internal features of travertine mounds includes both upward decrease (up to subhorizontal) and downhill increase (up to subvertical) of clinostratification angles suggesting progradational mechanisms. The basic components of travertine deposits are aquatic sessile plants and microbes, developing along water flows. Regardless their role in carbonate precipitation, organisms appear as living templates able to organize primary carbonate encrustations along their growth directions. This results in early-lithified skeletal sedimentary bodies with rapid upward growth. Travertine accumulation transforms original slopes into gently inclined flat areas (travertine terraces), limited downhill by steeper slopes, eventually evolving in subvertical escarpments. Both terraces and escarpments are depositional rather then erosional features, being geomorphic expression of very shallow lacustrine deposits and waterfall structures respectively. Modern to fossil comparison among travertine systems located in southern and central Italy suggest a sedimentary model based on continued feedback between processes and products, which increase the complexity of depositional system over time. Encrusting waters display chemical gradients along their flow, modulating shape and downhill development of resulting travertine deposits. Upward growth gradually decreases original slope angles, so that the water flow is laterally displaced toward adjacent areas of steeper slope, accounting for juxtaposition of travertine mounds. By means of continuous lateral shifting of encrustation process travertine deposition gradually transform original slopes in gently inclined flat areas

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Detecting sedimentary cycles using autocorrelation of grain size.

    PubMed

    Xiao, Shangbin; Li, Rui; Chen, Muhong

    2013-01-01

    Detection of sedimentary cycles is difficult in fine-grained or homogenous sediments but is a prerequisite for the interpretation of depositional environments. Here we use a new autocorrelation analysis to detect cycles in a homogenous sediment core, E602, from the northern shelf of the South China Sea. Autocorrelation coefficients were calculated for different mean grain sizes at various depths. The results show that sediments derived from rapid depositional events have a better autocorrelation. Analysis of two other cores confirms this result. Cores composed of sediments deposited quickly under stable and/or gradually changing hydrodynamic conditions, have higher autocorrelation coefficients, whereas, those composed of sediments deposited during calm periods have relatively low autocorrelation coefficients. It shows that abrupt changes in autocorrelation coefficients usually indicate the existence of a boundary between adjacent sedimentary cycles, with each cycle beginning with a high positive autocorrelation coefficient of grain size and ending with a low negative one.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. An object-oriented expert system for sedimentary basin analysis

    SciTech Connect

    Miller, B.M. )

    1991-08-01

    Some of the basic earth-science problems that span industry, academia, and the government, and are likely candidates for the application of knowledge-based expert systems, pertain to energy and mineral resource studies. Most of the world's energy resources and many of its metallic and mineral resources are derived from complex sources in sedimentary basins. A comprehensive basin analysis requires an understanding of data from many specialties including sedimentology, stratigraphy, geophysics, structural geology, and geochemistry. Such as integrated analysis is almost impossible without a computer. Research efforts in the US Geological Survey are currently being directed at exploring the feasibility of applying expert systems and knowledge acquisition techniques to the design and development of a global system of classification and geological analysis of sedimentary basins to assess their petroleum potential. The primary objective is the design of a prototype object-oriented expert system, interfaced with a Geographic Information System (GIS), that captures both the logic used to define the geologic concepts and the reasoning under uncertainty that enables geologists to understand and reconstruct geologic history of a sedimentary basins. The systems are designed to analyze the traditional concepts of source, reservoir, and trapping mechanism; to help diagnose geologic conditions favorable for the occurrence of petroleum or other energy resources; and to assist in assessing these resources. The design and content of the expert systems program is discussed for application to basin analysis studies to aid in petroleum resource assessment.

  3. 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.

  4. 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.

  5. Arctic coastal zone mapping: Evolution of sedimentary coasts in Greenland

    NASA Astrophysics Data System (ADS)

    Bendixen, M.; Kroon, A.

    2015-12-01

    Climate change threatens many of the coastal areas all over the world. In the Arctic, the warming happens at a rate which is three times faster than the global average increasing the pressure on the coast. Arctic coasts differ from coasts in lower latitude in terms of the natural conditions prevailing, i.e. sea-ice, permafrost, and thermal erosion. These factors are likely to change with an increasing temperature, and thereby the erodibility of the shores and the erosivity of the coastal processes are changing. The majority of studies on arctic coasts focus on tundra coasts. Here, there is a general increase of coastal erosion rates over the last decades. However, the arctic coastal areas of Greenland differ; they are often close to hard rock protrusions and are characterized by large differences in geomorphology, erodibility of sediments, and erosivity by coastal processes. Sedimentary coasts in Greenland are only sporadically investigated, and it is thus difficult to predict the impact of climate changes in these areas. With this work we focus on sedimentary coasts in Greenland and present shoreline analysis of two sedimentary coastal sites. We show how the position of the shoreline has changed since the 1930'ies and we address the responsible factors controlling this evolution. The hotspots of coastal change are all located near delta mouths and the detected changes are coupled to dominating process occurring here.

  6. 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.

  7. 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

  8. 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.

  9. 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

  10. 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

    2016-05-01

    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 ˜3,000-m-thick Jurassic sedimentary sequence in the Qiangtang Basin on the central Tibetan Plateau, which is called the Yanshiping Group, recorded these geological events. However, the chronology of the sequence is surprisingly poorly constrained. Here, we perform a detailed palaeomagnetic analysis on the ˜1,060-m-thick middle and upper portions of the Yanshiping Group (the Xiali and Suowa Formations) in the Yanshiping section of the eastern Qiangtang Basin. Three bivalve zones at stratigraphic intervals of ˜40-140 m, 640-800 m 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.

  11. Intra-crater sedimentary deposits at the Haughton impact structure, Devon Island, Canadian High Arctic

    NASA Astrophysics Data System (ADS)

    Osinski, Gordon R.; Lee, Pascal

    2005-12-01

    Detailed field mapping has revealed the presence of a series of intra-crater sedimentary deposits within the interior of the Haughton impact structure, Devon Island, Canadian High Arctic. Coarse-grained, well-sorted, pale gray lithic sandstones (reworked impact melt breccias) unconformably overlie pristine impact melt breccias and attest to an episode of erosion, during which time significant quantities of impact melt breccias were removed. The reworked impact melt breccias are, in turn, unconformably overlain by paleolacustrine sediments of the Miocene Haughton Formation. Sediments of the Haughton Formation were clearly derived from pre-impact lower Paleozoic target rocks of the Allen Bay Formation, which form the crater rim in the northern, western, and southern regions of the Haughton structure. Collectively, these field relationships indicate that the Haughton Formation was deposited up to several million years after the formation of the Haughton crater and that they do not, therefore, represent an immediate, post-impact crater lake deposit. This is consistent with new isotopic dating of impactites from Haughton that indicate an Eocene age for the impact event (Sherlock et al. 2005). In addition, isolated deposits of post-Miocene intra-crater glacigenic and fluvioglacial sediments were found lying unconformably over remnants of the Haughton Formation, impact melt breccias, and other pre-impact target rock formations. These deposits provide clear evidence for glaciation at the Haughton crater. The wealth and complexity of geological and climatological information preserved as intra-crater deposits at Haughton suggests that craters on Mars with intra-crater sedimentary records might present us with similar opportunities, but also possibly significant challenges.

  12. 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.

  13. 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

  14. Coastal changes in sedimentary environments on Disko Island, western Greenland

    NASA Astrophysics Data System (ADS)

    Bendixen, M.; Kroon, A.; Nielsen, L.

    2013-12-01

    Global climate change affects Arctic coasts. A rising sea level, increasing fresh water fluxes from glaciers, and decreasing sea-ice extent increase the pressure on the sedimentary areas in these high-latitude regions. In Arctic coastal environments, permafrost, sea-ice, and fluvial input from glacial melt water have an impact in controlling the evolution of the coast. In this study we present the results of annual to decadal coastal changes (rates of change in shoreline positions) along the southern Disko Island in Greenland. These changes are detected and quantified using rectified aerial photos and satellite images. The oldest images used are from the 1940's and the most recent one was 2012. Additional field-measurements are made to identify the responsible processes that cause the coastal development in more detail. The southern coast of Disko Island includes two distinct sedimentary deltas: Skansen and Tuapaat. They consist of sandy, gravelly, and pebbly material. Lagoons, spits, and beaches are present on these deltas and our analyses reveal that these characteristic coastal features have undergone significant morphological changes within the last 60 years: The identified changes within the deltas show a migration of the delta mouths over more than 400 m in an eastward direction, and thus closure of the former inlets. These rapid coastal responses are probably caused by a combination of a shift in channel lobe on the delta plain after 1985, combined with a predominant wave-driven alongshore sediment transport to the east. The shift in delta channels is often recognized as the main responsible agent in controlling the evolution of the sedimentary sites.

  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. Sedimentary fill of 1100 Ma mid-continent rift system

    SciTech Connect

    Ojakangas, R.W.

    1986-05-01

    In the Lake Superior region, four sequences of sedimentary rocks reflect the tectonic-sedimentary framework before, during, and after the magmatic event that resulted in 10,000 m of dominantly basaltic volcanic rocks and large layered gabbroic intrusions. The oldest sequence includes four geographically separated, thin (100 m) pre-volcanic, white to pink, quartzose sandstone units that were deposited in braided alluvial plain-lacustrine environments within the shallow basin that was the initial manifestation of rifting. The second sedimentary sequence consists of immature sediment, largely derived from the volcanic sequence and deposited in alluvial fan, fluvial, and lacustrine environments during intervals between extrusive episodes. These red silty to conglomeratic units range from a few centimeters to hundreds of meters in thickness. The Oronto Group and the younger Bayfield Group and their equivalents are post-volcanic, dominantly red-bed sequences of siltstone, sandstone, and conglomerate, deposited in alluvial fan, fluvial, and lacustrine environments within the elongate basin. The Oronto Group (600 m) includes the Copper Harbor Conglomerate, the Nonesuch Shale (gray, carbonaceous, pyritiferous, and cupriferous argillaceous siltstone) and the Freda Sandstone. The Bayfield Group (2100 m) includes the Orienta Sandstone, the Devils Island Sandstone (100 m of orthoquartzite), and the Chequamegon Sandstone. Whereas volcanic detritus is dominant in most of the Oronto Group and the equivalent Solor Church Formation, extrabasinal granitic detritus dominants in the Bayfield Group and its equivalents (Fond de Lac Formation, Hinckley Sandstone, and Jacobsville Sandstone). Paleocurrent data indicate a general basinward transport of sediment during deposition of the four sequences, 1100 Ma(.) to 950 Ma(.).

  17. Beryllium-10 in Australasian tektites: evidence for a sedimentary precursor

    SciTech Connect

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

    1982-11-19

    Each of seven Australasian tektites contains about 1 x 10/sup 8/ atoms of beryllium-10 (half-life, 1.53 x 10/sup 6/ 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.

  18. Beryllium-10 in australasian tektites: evidence for a sedimentary precursor.

    PubMed

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

    1982-11-19

    Each of seven Australasian tektites contains about 1 x l0(8) atoms of beryllium-10 (half-life, 1.53 x 10(6) 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. 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

  20. Geophysical characterization of the sedimentary environments in Lago Puyehue

    NASA Astrophysics Data System (ADS)

    Charlet, F.; Bertrand, S.; Chapron, E.; Fagel, N.; de Batist, M.

    2003-04-01

    The Chilean Lake District, located in Southern Chile, comprises 17 lakes at the foothill of the Cordillera de los Andes. These lakes, dammed by frontal moraines, were formed during the last deglaciation (12500-12000 BP). Their sedimentary infilling has the potential to contain a complete and continuous Holocene sedimentary record of environmental and climatic changes having affected the area. High-resolution reflection seismic data (sparker and pinger) collected during the 2001-2002 expedition in the framework of the Belgian ENSO-CHILE project have allowed us to select two lakes for the collection of long and short sediment cores: 1. Lago Icalma (38°50´S, alt. 1150 m) is located in the Cordillera de los Andes, in the upper part of the Bio-Bio River. Its watershed (148 km2) is dominated by a soft post-glacial sediment cover, interrupted by two important pumice layers. According to the high-resolution seismic survey, the 70m-thick sedimentary infilling consists of morainic deposits, under- and interflows and laminated lacustrine deposits. The western part of the main basin represents an elevated platform, free of the influence of bottom-currents and turbidites and possibly consisting of interflow deposits. Core descriptions and physical property analyses of sediments (gamma-density, low and high-resolution magnetic susceptibility) suggest that the deposits consist of an alternation of volcanic deposits and terrigenous sediments correlated on pinger profiles, showing the presence of several low-amplitude layers. 2. Lago Puyehue (40°40´S, alt. 185 m) is located at the foothill of the Cordillera de los Andes and presents a glacial morphology much more complicated than Lago Icalma. Its watershed is larger (1267 km2) and dominated by Quaternary and Tertiary volcanic rocks. The lake is composed, in its western part, by a large basin, filled by 250 m of sediments, as can be deduced from sparker profiles. The eastern part of the lake presents a complex substratum

  1. Heterogeneity in Sedimentary Aquifers: Effects on Chlorinated Solvent Mass Storage

    NASA Astrophysics Data System (ADS)

    Kalinovich, I. K.; Allen-King, R.; Carlone, D.; Clarke, D.; George, S. S.; Weissmann, G. S.; McNamara, K. C.; Frechette, J. D.

    2011-12-01

    Dynamic mass storage of hydrophobic organic contaminants (HOC) is affected by physical and geochemical aquifer heterogeneities, creating a need for targeted remediation. In glacially-derived aquifers (such as the well-known Borden study site), sedimentary lithocomponents contain varying types and quantities of highly-sorbing carbonaceous matter. These lithocomponents are distributed throughout the aquifer through transport and depositional processes. Compared to fine-grained lithofacies, lithofacies with greater texture have increased magnitudes and variability of Kd (equilibrium sorption coefficient) due to lithocomponent variety and deposition. Sedimentological features with greater physical and geochemical heterogeneity (such as scours and troughs) are potential areas for mass storage of HOCs, requiring targeted remediation efforts. In this study, a spatial data set collected from the Borden study site is combined with a nearby outcrop analogue to investigate how geochemical and physical heterogeneity influences the mass storage of HOCs. Outcrop analogue-derived lithofacies from a nearby sand quarry allow us to quantify geochemical heterogeneity in the sedimentary architectural context. Each scour feature consists of several sediment facies layered on top of one another in identifiable and predictable patterns. These patterns extend beyond the massive packages of medium grained facies; they include fine grained facies toward the top of the scour. Outcrop investigations of spatial deposition of lithocomponents and Kd analysis shows that areas of increased lateral heterogeneity and overall Kd magnitude are associated with the sharp contact at the bottom of these scours with fine-grained facies. Both lateral heterogeneity and Kd are associated with the abundance of dark and light carbonaceous lithocomponents. Particle size, lithocomponent analysis and distinct cumulative density functions for Kd (of chlorinated volatile organic compounds) were derived for

  2. In situ NMR analysis of fluids contained in sedimentary rock

    PubMed

    de Swiet TM; Tomaselli; Hurlimann; Pines

    1998-08-01

    Limitations of resolution and absorption in standard chemical spectroscopic techniques have made it difficult to study fluids in sedimentary rocks. In this paper, we show that a chemical characterization of pore fluids may be obtained in situ by magic angle spinning (MAS) nuclear magnetic resonance (NMR), which is normally used for solid samples. 1H MAS-NMR spectra of water and crude oil in Berea sandstone show sufficient chemical shift resolution for a straightforward determination of the oil/water ratio. Copyright 1998 Academic Press.

  3. 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

  4. 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

  5. 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

  6. 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.

  7. Beryllium-10 in australasian tektites: evidence for a sedimentary precursor.

    PubMed

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

    1982-11-19

    Each of seven Australasian tektites contains about 1 x l0(8) atoms of beryllium-10 (half-life, 1.53 x 10(6) 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. PMID:17771035

  8. 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.

  9. 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.

  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. Sedimentary facies and ecosystems in the Balearic shelf

    SciTech Connect

    Fornos, J.J.; Pomar, L.; Rodriguez-Perea, A.

    1988-08-01

    Sediments of the Balearic platform are mainly carbonate with low percentages of terrigenous influx. These influences are located in littoral areas related to rushing streams. Main bioclastic components are red algae, mollusks, foraminifers, and bryozoans. Terrigenous components are mainly calcareous lithoclasts. Productive ecosystems are built by sea grasses of Posidonia oceanica and marl. Less important are coralline Vidalia volubilis, Cymodocea nodosa, Caulerpa prolifera, and several communities of photophile algae. Each of these ecosystems is the origin of their correlated biofacies. These biofacies are medium biogenic sands, algal sands and gravels, muddy sands, and coarse terrigenous sands. Sediment distribution is directly related to ecosystem distribution, which can be matched with depth and energy variables. Hydrodynamic circumstances are revealed by minor sedimentary structures, like wavy and current ripples, or by hectometric sand waves placed south of Minorca Island at a depth of 48 to 68 m. Sedimentary grains are suffering from erosion and boring processes, which are produced mainly by fungi but also by sponges, polychaetes, bryozoans, and mollusks. These bioerosions are sometimes accompanied by mechanical abrasion and less frequently by chemical corrosion, and this is the principal source of carbonate mud that is transferred to the outer shelf.

  12. Geological study of sedimentary basins using SPOT data

    NASA Astrophysics Data System (ADS)

    Pisot, Nathalie; Xavier, Jean-Paul; Miegebielle, Véronique; Coquelet, Dominique; Leymarie, Pierre

    This paper illustrates the benefits of DTMs created from SPOT images for the exploration of sedimentary basins. We chose an example located in the Ebro sedimentary basin in Spain, characterized by good outcropping conditions and slight deformations. The data used consist of a pair of SPOT panchromatic images and a SPOT XS image. The work consists of making up a 3D database, followed by interpretation of stereo pairs computed from orthoimages and the DTM. This interpretation is made on a stereoscopic desk and results in a digital file containing in the form of vectors all the observed faults and lithology. These vectors are then used to make calculations on the geometry of the objects they represent: we demonstrate that we can accurately measure layer directions and dips, sediment thicknesses and fault throws. Synthesis of perspective views made at the same time provide a good understanding of the structures and help to test their geometric consistency. Thus knowledge about relief given by DTMs helps to interpret remote detection images in 3D space, and particularly to accurately quantify the results of this interpretation.

  13. 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. PMID:25532769

  14. Phanerozoic Sedimentary Corg:P Ratios and Paleocean Ventilation

    NASA Astrophysics Data System (ADS)

    Algeo, T. J.

    2004-12-01

    Phosphorus is probably the major limiting nutrient on marine primary productivity at geological timescales, although other elements (e.g., N, Fe) can be transiently biolimiting. It has been inferred that remineralization of organic P and upwelling of nutrient-rich deepwaters have the potential to stimulate primary productivity, and that measurements of sedimentary (C:P)org ratios in ancient sediments can yield insights on nutrient fluxes and productivity levels in paleoceans. However, recent work has shown that (1) sedimentary (C:P)org ratios exceed the Redfield ratio (106:1) in most environments as a result of preferential bacterial destruction of labile P-bearing compounds, and (2) the inorganic P fractions associated with Fe-bound and authigenic phosphate phases in anoxic sediments are largely of organic derivation, representing remineralized P that has been fixed through redox-related processes. These insights suggest that the most useful measure of nutrient regeneration is the nondetrital P fraction of sediments, a variable that is rarely determined but that can be adequately proxied by total P in anoxic facies, in which the detrital P fraction is typically small. In this study, Corg:P ratios were determined for 60 anoxic facies of Cambrian through Recent age. The Recent facies yield a mean Corg:P of 65±25, values similar to those for most anoxic facies of Mississippian and younger age. In contrast, many Cambrian-Devonian anoxic facies yield substantially higher Corg:P ratios, with the highest values (>400) in the Middle-Upper Cambrian and Middle-Upper Devonian. For the Phanerozoic as a whole, the logarithmic mean Corg:P ratio declines by a factor of four, from ~260:1 in the Cambrian to 65:1 in the Recent, a statistically robust result. Given the importance of redox controls on sedimentary P retention at a local scale, this pattern can be interpreted as a record of benthic redox conditions through time, i.e., paleocean ventilation. Although Recent anoxic

  15. Petroleum potential of volcanogenic and volcano-sedimentary rocks in ancient and recent island arcs: Caucasus, Komandorskie, and Kuril islands, eastern Kamchatka

    SciTech Connect

    Levin, L.E. )

    1993-09-01

    In the Late Cretaceous-Eocene, subduction of the Tethys oceanic plate under the island arc of the lesser Caucasus contributed to the appearance of the special conditions favorable for petroleum occurrence: (1) tectono-magmatic destruction of the crust of the Transcaucasus median massif and formation of hydrocarbon traps of different types and origins, and (2) high heat flow lasting until the recent epoch. These led flow-intensive generation of hydrocarbons in the shallow-water sediments of the paleoshelf of the Transcaucasus massif and accumulation of hydrocarbons not only in the sedimentary but also in the volcanogenic and volcano-sedimentary reservoirs (Samgori-Patardzeuli, Muradhanly fields, etc.). At the end of the Oligocene, the geodynamic setting in the northwestern margins of the Pacific Ocean was mainly similar to that within the Transcaucasus median massif. At the end of Oligocene-Miocene, such conditions determined the tectono-magmatic destruction of the continental crust and formation of the series of interarc rifts. The main fields of Japan, with accumulations in the volcanogenic and volcano-sedimentary rocks, are concentrated here. Its analog is the rift located in the southern part of a single east Kuril basin, where petroleum occurrence is only inferred. In the separate troughs, the thickness of the volcano-sedimentary cover is 4-6 km. The stratigraphic section of the cover contains the volcanic and volcano-sedimentary sediments of the Neogene-Pleistocene. The studies of the sections of the Komandorskie islands, eastern Kamchatka, Kuril Islands, and western Sakhalin indicate that distribution of reservoirs depends on the stage of evolution of the rifts and adjacent island arcs.

  16. 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.)

  17. {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.

  18. New paleomagnetic data from Late Neoproterozoic sedimentary successions in Southern Urals, Russia: implications for the Late Neoproterozoic paleogeography of the Iapetan realm

    NASA Astrophysics Data System (ADS)

    Lubnina, Natalia V.; Pisarevsky, Sergei A.; Puchkov, Victor N.; Kozlov, Vjacheslav I.; Sergeeva, Nina D.

    2014-07-01

    We present the results of paleomagnetic study of Ediacaran sedimentary successions from the Southern Urals. The analysis of the sedimentary rocks of the Krivaya Luka, Kurgashlya and Bakeevo Formations reveal stable mid-temperature and high-temperature remanence components. Mid-temperature components were acquired during Devonian (Bakeevo Formation) and Late Carboniferous-Early Permian remagnetization events. The high-temperature components in Kurgashlya and Bakeevo Formations are interpreted to be primary, because they are supported by a positive conglomerate test (Bakeevo Formation) and magnetostratigraphic pattern (Kurgashlya Formation). The high-temperature component in the Krivaya Luka Formation is interpreted to be a Late Ediacaran overprint. Our new paleomagnetic poles together with some previously published Ediacaran poles from Baltica and Laurentia are used herein to produce a series of paleogeographic reconstructions of the opening of the Iapetus Ocean.

  19. 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…

  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. 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

  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. Polarographic determination of tungsten and molybdenum in sedimentary rocks

    SciTech Connect

    Vakhobova, R.U.; Lykova, F.P.; Milyavskii, Yu. S.; Rachinskaya, G.F.

    1985-12-01

    In order to determine microamounts of tungsten and molybdenum, one the most sensitive versions of polarography is used in this paper, called catalytic currents. In the development of a procedure for the determination of tungsten and molybdenum in geochemical items, the reduction of hydroxylamine (HA) is used, catalyzed by tungsten and molybdenum compounds in the presence of pyrocatechol, as on a background of dicarboxylic acids and hydroxy acids the HA reduction half-wave potentials, catalyzed by these elements, coincide. The investigations were conducted on a PPT-1 polarograph in the classical regime in a thermostatically controlled cell with a mercury dripping electrode and a saturated calomel comparison electrode. The authors develop a procedure for the simultaneous determination of n.10/sup -5/-n.10/sup -4/% of tungsten and molybdenum in sedimentary rocks.

  4. Acadian dextral transpression and synorogenic sedimentary successions in the Appalachians

    SciTech Connect

    Ferrill, B.A.; Thomas, W.A.

    1988-07-01

    The successive Seboomook-Littleton (northern Appalachians) and Catskill-Pocono (central Appalachians) clastic wedges suggest oblique convergence and southwestward migration of Acadian orogeny beginning in Early Devonian and continuing into Early Mississippian. Wrench-fault movement in Maritime Canada coincided with deposition of all but the earliest components of the Catskill-Pocono clastic wedge and continued into the Pennsylvanian. Contrasts between a thin, Lower to Middle Devonian shallow-shelf facies in the Alabama Appalachian fold-thrust belt and a time-equivalent, thick, shallowing-upward sedimentary to volcanic succession in the adjacent Talladega slate belt are interpreted to reflect a wrench-fault basin. A wrench-fault setting for Devonian rocks in Alabama integrated with manifestations of oblique convergence during the Acadian orogeny in the central and northern Appalachians can be accommodated in dextral transpression along the entire length of the Acadian Appalachian orogen.

  5. 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.

  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.

    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

  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. 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

  10. Thrace basin: An extensional Tertiary sedimentary basin in an area of major plate convergences, northwest Turkey

    SciTech Connect

    Turgut, S.; Atalik, E.

    1988-08-01

    The Thrace basin forms one of the largest Tertiary basins in Turkey. Paleontological and sedimentological evidence suggests sedimentation and basin formation commenced by a major transgression from the southwest in the middle to late middle Eocene. The basin formed over an extremely deformed crustal block. It straddles an Upper Cretaceous suture zone which later became a major mobile belt in Turkey. Syndepositional fault patterns and sedimentary thickness indicate the basin was evolved tectonically by north-south extension. Large listric normal faults and east-west depositional axis are evidence of this extension. Early marine sedimentation in the basin was accompanied by an intense volcanism which poured large quantities of ash into the depositional environment. Normal basement faults were active and great thicknesses of clastic sediments accumulated along faults. Reefal to shallow marine carbonates were deposited on shelves and over intrabasinal paleohighs. Sedimentation became regressive in the early Oligocene. Alternation of marine and nonmarine clastic deposition continued without interruption until the end of the Oligocene. By the late Oligocene to early Miocene, the whole basin was subjected to intense tectonism that caused uplift and faulting. Seismic reflection profiles reveal a very complex tectonic style in the basin. Fault-related inversion and flowage structures involving shale diapirism are quite common. Eocene and Oligocene shales are mature enough to generate economical quantities of hydrocarbons. Their source quality is fair to poor. Sand bodies in the Eocene-Oligocene series and reefal carbonates form the reservoir facies, and they are targets for exploration.

  11. 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.

  12. 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.

  13. Restudy of the sedimentary environment of Los Jabillos Formation of Northeastern Venezuela

    SciTech Connect

    Santiago, N. )

    1993-02-01

    From the study of five sections located on the southern flank of the Interior Range, we have determined the sedimentary characteristics of Los Jabillos Formation and propose a model for its deposition. During Oligocene time there were changes in the paleoslope direction of the basin, with a predominance of southwest to northeast. The relative variations of sea level, in this part of the Western Venezuelan basin were controlled by subsidence tectonic, which was of major influence in the sedimentation of Los Jabillos Formation. During this epoch and under these conditions, the shelf was covered by sediments from Guayana shield. There were deposits in a wave dominated delta, where the stream-mouth bars were continually reworked into a series of superimposed coastal bars. The littoral currents transported these sands sediments parallel to the coast, causing a decrease in thickness of the units both toward the east and the west. The sandy beds (beach and marine bar), deposits on both sides of stream mouth are preserved in outcrops in Querecual, Oro, and Areo rivers. They are composed of mature quartz sandstone, with good size selection and have, therefore, good permeability. Examples of the marine bar facies have also been studied in wells in the Maturin subbasin where data were obtained from a conventional core.

  14. 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.

  15. 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).

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. Gas injection into and migration through layered sedimentary sequences

    NASA Astrophysics Data System (ADS)

    MacMinn, C. W.; Foschi, M.; Levell, B. K.; Cartwright, J. A.

    2015-12-01

    Gas migration within sedimentary basins is central to both carbon capture and storage (CCS) and hydrocarbon exploration, both of which involve fluid flow over very large length and time scales (102 to >105 m; 1 to >106 y). Seismic imaging is the primary tool for in-situ gas detection in both cases, but it is limited in resolution and can only provide qualitative information about the presence and distribution of gas. Theoretical models can be a strong complement to seismic observations, providing quantitative tools to inform physical understanding, answer basic feasibility questions, and, in CCS, to assess environmental risk and estimate storage capacity. Here, we develop a new model for gas injection into and migration through a multi-layered sedimentary sequence, where the source may be a wellbore (as in CCS) or a natural influx from a deeper source rock or reservoir. We idealize the sequence as consisting of alternating reservoir-like and seal-like layers, where seals are thinner and more fine-grained. For simplicity, we use a sharp-interface model for gas and water migration within each layer, adopting the assumption of vertical-flow equilibrium. We allow for compressibility in both fluids and, crucially, we also allow for leakage of both fluids across the seals, where the gas is subject to a capillary threshold. The model allows us to better understand how leakage enables inter-layer pressure communication, and how this impacts the evolution of the gas distribution in the sequence both during and after injection. The model also supports lateral and vertical heterogeneity in the permeability field, and in the capillary threshold, allowing us to evaluate the effect of leakage within highly-heterogeneous sequences.

  1. Predicting the transport properties of sedimentary rocks from microstructure

    SciTech Connect

    Schlueter, E.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.

  2. Tectonic and sedimentary evolution of the Luna field area, Italy

    SciTech Connect

    Roveri, M. )

    1990-05-01

    The Luna gas field is located near Crotone (Calabria region, southern Italy) in a shallow-water/onshore area. It was discovered and put into production during the early 1970s. Up to now it has produced 19 {times} 10{sup 9} sm{sup 3} of gas; its productivity (50 {times} 10{sup 6} sm{sup 3}/y) has remained virtually unaltered since the beginning. The field is located on the axial culmination of a thrust-related anticline of the Apennine postcollisional thrust belt; it can be roughly subdivided into two areas characterized by different stratigraphic contexts. In the northern and central parts of the field is a structural trap. Reservoir rocks are Serravallian to Tortonian deep marine resedimented conglomerates and sandstones. These deposits represent part of the infill of a middle-upper Miocene foredeep. Reservoir rocks are now thrusted, eroded, and unconformably overlain by lower Pliocene shales, which are the most important seal in this part of the field. In the southern part of the field is a combination trap. Reservoir rocks are upper Tortonian shallow-water sandstones. They lap onto a Tortonian unconformity related to a tectonic phase which split the previous foredeep into minor piggyback basins. The upper Tortonian sandstones are overlain and sealed by Messinian shales and evaporites. Tectonosedimentary evolution of the area and, consequently, areal distribution and geometry of sedimentary bodies - both potential reservoirs and seals - have been reconstructed using a sequence stratigraphy approach. The sedimentary record has been informally subdivided into five main depositional sequences bounded by unconformities or their correlative conformities; classic facies analysis and petrophysical, seismic, and biostratigraphic data have been utilized to define the internal characteristics of each sequence.

  3. 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.

  4. 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.

  5. 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

  6. 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. PMID:27020346

  7. 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.

  8. 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.

  9. 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.

  10. [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.

  11. 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.

  12. Alga-like forms in onverwacht series, South Africa: oldest recognized lifelike forms on Earth.

    PubMed

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

    1968-09-01

    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, littlealtered sedimentary rocks on Earth. The basal Onverwacht sediments lie approximately 10,000 meters stratigraphically below the Fig Tree sedimentary rocks, from which similar organic microstructures have been interpreted as alga-like microfossils. The Onverwacht spheroids and filaments are best preserved in black, carbonrich 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.

  13. 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.

  14. 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.

  15. Reaction capacity characterization of shallow sedimentary deposits in geologically different regions of the Netherlands.

    PubMed

    Griffioen, Jasper; Klein, Janneke; van Gaans, Pauline F M

    2012-01-01

    Quantitative insight into the reaction capacity of porous media is necessary to assess the buffering capacity of the subsurface against contaminant input via groundwater recharge. Here, reaction capacity is to be considered as a series of geochemical characteristics that control acid/base conditions, redox conditions and sorption intensity. Using existing geochemical analyses, a statistical regional assessment of the reaction capacity was performed for two geologically different areas in the Netherlands. The first area is dominated by Pleistocene aquifer sediments only, in the second area a heterogeneous Holocene confining layer is found on top of the Pleistocene aquifer sediments. Within both areas, two or more regions can be distinguished that have a distinctly different geological build-up of the shallow subsurface. The reactive compounds considered were pyrite, reactive Fe other than pyrite, sedimentary organic matter, carbonate and clay content. This characterization was complemented by the analysis of a dataset of samples newly collected, from two regions within the Pleistocene area, where the sedimentary facies of samples was additionally distinguished. The statistical assessment per area was executed at the levels of region, geological formation and lithology class. For both areas, significant differences in reaction capacities were observed between: 1. different lithology classes within a geological formation in a single region, 2. identical geological formations in different regions and 3. various geological formations within a single region. Here, the reaction capacity is not only controlled by lithostratigraphy, but also by post-depositional diagenesis and paleohydrology. Correlation coefficients among the reactive compounds were generally higher for sand than for clay, but insufficiently high to allow good estimation of reactive compounds from each other. For the sandy Pleistocene aquifer sediments, the content of reactive compounds was frequently

  16. 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

  17. 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.

  18. 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

  19. 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).

  20. 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

  1. 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

  2. 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

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

    NASA Astrophysics Data System (ADS)

    Salem, Ahmed; Williams, Simon; Samson, Esuene; Fairhead, Derek; Ravat, Dhananjay; Blakely, Richard J.

    2010-09-01

    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

  4. 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

  5. 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

  6. Sedimentary archives of extreme flooding events in the Northeastern Caribbean

    NASA Astrophysics Data System (ADS)

    Woodruff, J. D.; Donnelly, J. P.; Scileppi, E.

    2004-12-01

    Flooding associated with both hurricanes and tsunamis can be extremely hazardous to coastal communities. Accurately reconstructing the past history and intensity of these extreme events is valuable when assessing future risks to specific coastal regions. Overwash deposits preserved within backbarrier lagoons and salt ponds can provide a means for documenting previous flooding activity; however, the details of how these individual flooding events are recorded within these environments is still not completely understood. An analysis of sediment cores collected from a lagoon system in the Northeastern Caribbean (Laguna Playa Grande, Vieques, Puerto Rico) reveal coarse-grained deposits interlaminated within fine-grain lagoon sediments. These coarse-grained laminae consist of beach and nearshore sediments and can be mapped across the lagoon. These coarse-grained strata are likely overwash deposits that may provide a high-resolution record of extreme flooding events in the region over the last 5000 years. Understanding the sedimentary record of historical events of known intensity and duration is necessary, however, in order to make inferences about the cause of prehistoric coarse-grained layers. Vieques has experienced relatively little coastal development and contains a well documented history of storm and tsunami activity since its colonization in the 16th century. The island thus provides an excellent opportunity to study how recent extreme flooding events have been preserved in a natural lagoon system. Overwash deposits preserved at Laguna Playa Grande over the last 200 years are analyzed in order to identify which historically documented flooding events appear to have left a sedimentological record. These deposits are initially identified based on high resolution grain-size analysis and x-radiographic imaging. Activity levels for Pb-210 and C-137 are measured to date recent sediments (over the past 200 yrs) and to link individual coarse-grained strata with

  7. 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.

  8. 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…

  9. Seri Kinship Terminology.

    ERIC Educational Resources Information Center

    Moser, Mary B.; Marlett, Stephen A.

    The Seri language contains over 50 kinship terms and represents one of the most highly elaborated kinship systems described to date. This paper discusses Seri kinship terminology and centers around, but is not limited to, the set of obligatory possessed noun stems that are inflected with the following possessive prefixes": "hi-,""ma-," and "a-."…

  10. 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.

  11. 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.

  12. New Insights into the Sedimentary Dynamics along Carbonate Slopes

    NASA Astrophysics Data System (ADS)

    Wunsch, Marco; Betzler, Christian; Lindhorst, Sebastian; Lüdmann, Thomas; Eberli, Gregor

    2016-04-01

    Hydroacoustic, sedimentological and seismic data of the leeward slope of Great Bahama Bank and the windward slope of the adjacent Cay Sal Bank provide new insights into carbonate platform slope sedimentation. Our study focuses on the diversity and complexity of the slope morphologies and sedimentary patterns which characterize the youngest high-frequency sequence, forming since the Last Glacial Maximum. It is shown that both carbonate platform slopes are dissected by furrows, gullies and channels which are genetically not related. Along the windward slope of Cay Sal Bank, toe of slope erosion, in conjunction with the local tectonic regime is responsible for channel incisions. Our data show that these channels were active during the regression after the last interglacial highstand of sea level. During this regression, downwelling transported platform sediment downslope, which was redistributed along the slope by contour currents. It is also shown that large mass transport complexes at the leeward slope of Great Bahama Bank formed during the last sea level lowstand, probably triggered by the release of pore-water pressure. These MTC created a complex slope morphology of gullies and scarps. These gullies act as a point source by confining the exported platform sediments during the present day sea level highstand.

  13. Recent sedimentary facies in interdistributary basin, Mississippi delta

    SciTech Connect

    Hi, I.Y.; Kosters, E.; Moslow, T.F.

    1986-05-01

    Five sedimentary facies have been recognized from 23 vibracores in an abandoned interdistributary basin of the St. Bernard delta lobe, 15 km southeast of New Orleans. They are: (1) detrital clays containing shell fragments and lenticular laminations, interpreted as a bay facies; (2) laminated to massive-appearing, fine grained sandbeds averaging 10-20 cm in thickness, of possible overbank or crevasse splay origin; (3) thinly interbedded, parallel laminated and ripple laminated, sandy and clayey silts forming 50 to 70-cm-thick sequences that increase in clay content upwards, interpreted as flood events during overbank deposition; (4) extensively rooted detrital clays with less than 10% organic matter as disseminated plan material, representing a transitional, brackish-to-saline marsh facies; (5) organic-rich clays (35-75% organic matter) and peats (> 75% organic matter), interpreted as marsh and swamp facies. Major depositional environments observed on the present deltaic plain include irregular-shaped lakes, distributary channels, natural levees, overbank splays, small meandering channels, oyster reefs, and swamp, brackish and saline marshes.

  14. Fission-track dating of volcanically derived sedimentary rocks

    SciTech Connect

    Kowallis, B.J.; Heaton, J.S.; Bringhurst, K.

    1986-01-01

    Depositional ages of sedimentary rocks can be determined using fission-track single grain ages on zircons from layers of volcanic ash or bentonite, even when the layers have been contaminated by older grains. This is done by compiling an age probability distribution or age spectrum for a sample from individual grain ages. An age spectrum is a simple and unambiguous way of testing for contamination and extracting useful age information. The youngest peak in the age spectrum approximates the time of deposition. In most contaminated samples, 30 or more grains should be counted to produce a reliable spectrum. However, useful, reproducible ages can be obtained by counting less than 10 grains in samples where most of the older, contaminating grains can be removed. The few older grains that remain after removing the obviously abraded ones may then be eliminated by examining the age spectrum. Although ages determined in this way are probably not precise enough for use in defining stratigraphic boundaries, they still provide a means of obtaining an isotopic age in sediments that cannot be dated by other radiometric methods. 18 references, 3 figures, 3 tables.

  15. long interval microtremor array survey in sedimentary basin

    NASA Astrophysics Data System (ADS)

    Yoshimi, M.; Sugiyama, T.

    2011-12-01

    Microtremor array survey is one of the easiest passive inspection methods to estimate the subsurface velocity structure of sedimentary basin. Since the method utilizes ambient noise, of which stochastic features are not always stable both spatially and temporally, longer observation interval is necessary to obtain reliable results. We conducted microtremor array surveys each observation interval is more than ten days to test robustness of the microtoremors (frequency range: 0.1 to 1 Hz) and phase velocities estimation. Velocity seismometers with natural period more than 5 sec. are deployed connected with 24 bit A/D, GPS time-calibrated data loggers. Each observation comprises of twelve stations arranged as three regular triangle arrays with radii several hundred meters to several kilometers to enable wide-band phase velocity estimation (0.1 to 1 Hz at maximum) necessary for Vs estimation at each site (south Niigata, central Japan). Each continuous data are segmented to hourly data sets, and they are analyzed with SPAC method to obtain phase velocity estimations. Estimated phase velocities are fluctuated especially in the lower frequency range (say, below 0.3 Hz). Our observation shows importance of longer interval observation to obtain reliable phase velocity estimates with microtremor array survey.

  16. 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.

  17. 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. PMID:26667911

  18. Climatically induced sedimentary cycles in Pliocene deep-water carbonates

    SciTech Connect

    Gardulski, A.F. )

    1991-03-01

    Two DSDP sites (86 and 94) on the Campeche ramp in the southern Gulf of Mexico penetrated more than 100 m of Pliocene pelagic ooze. The ooze is primarily carbonate, with a much smaller volcanic ash component than occurs in some Pleistocene sediments at these sites. Cores recovered from these holes display variations in carbonate mineralogy as well as total carbonate and sand abundances that are correlated with the oxygen isotope stratigraphy. Diagenetic loss of Mg-calcite is complete by the base of the Pleistocene, but aragonite, especially high-Sr aragonite forming algal needles that were transported off the shelf to the slope, persists through upper Pliocene cores. Variations in oxygen isotope ratios in planktonic foraminifera occur throughout the Pliocene, although the amplitude of those cycles is smaller than for the Pleistocene, with its more dramatic glacial-interglacial contrasts. As in overlying Pleistocene slope sediments, cooler intervals correspond with greater abundances of aragonite in the upper Pliocene section, reflecting a shift of the shallow, productive shelf seaward across the ramp surface during times of relatively low sea level. However, the aragonite abundances in the Pliocene are reduced on average compared to the Pleistocene. This difference is due in part to diagenetic loss, but also it likely reflects the overall higher sea level that apparently characterized Pliocene oceans, trapping more algal aragonite landward. Although sea level and climatic fluctuations were indeed less extreme in the Pliocene, they were still sufficient to generate sedimentary cycles in deep-water carbonates.

  19. 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.

  20. 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.

  1. 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.

  2. Sedimentary features observed in the tsunami deposits at Rikuzentakata City

    NASA Astrophysics Data System (ADS)

    Naruse, Hajime; Arai, Kazuno; Matsumoto, Dan; Takahashi, Hiroki; Yamashita, Shota; Tanaka, Gengo; Murayama, Masafumi

    2012-12-01

    The March 11, 2011 Tohoku-Oki tsunami triggered by an earthquake off the east coast of northeastern Honshu Island (Tohoku region), Japan, deposited large amounts of sediment on land, including the Sendai Plain and Sanriku Coast. This study reports on the characteristics of the tsunami deposits in Rikuzentakata City, southeastern Iwate Prefecture, northeastern Japan. A field survey identified the inundation pattern of the tsunami in this region and the facies model of the tsunami deposits at the bay-head deltas of estuarine systems. The tsunami deposits in Rikuzentakata City generally consist of one to four units that represent a discrete runup or backwash flow. Each unit is characterized by initial inverse grading and successive normal grading that correspond to the accelerating and decelerating stages of the flow, respectively. An internal erosional surface often developed between the inverse-graded and normal-graded units. It corresponds to the maximum shear velocity of the flow and truncates the underlying inverse-graded unit. In the case of the runup unit, silty fine-grained drapes overlay the graded sandy interval. A correlation of the sedimentary structures and grain fabric analysis revealed that the Tohoku-Oki tsunami inundated Rikuzentakata City at least twice and that the flow velocity exceeded 2.4 m/s. Paleontological analysis of the sediment and kriging estimation of the total volume of the tsunami deposit implied that the sediments were sourced not only from eroded beach sands but also from the seafloor of Hirota Bay or more offshore regions.

  3. 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.

  4. Sedimentary manganese carbonate deposits of the Molango District, Mexico

    SciTech Connect

    Alexandri, R. Jr.; Force, E.R.; Cannon, W.F.; Spiker, E.C.

    1985-01-01

    A shallow-marine sedimentary manganese carbonate deposit of Oxfordian-Kimmeridgian (Late Jurassic) age in the Molango district of Hidalgo, Mexico, contains one of the world's largest manganese resources. The bed presently mined, 1 to 9 thick and averaging 27% Mn, forms the lowest member of the Chipoco Formation throughout the district. Chipoco Fmn. carbonates and underlying Santiago Fmn. black shale form Taman Group. Deformation is severe but not penetrative. Additional supergene nsutite-pyrolusite deposits have formed on lower Chipoco Fmn. The ore bed is dark, laminated, a fine-grained carbonate rock and consists of pelletal(.)-textured rhodochrosite + minor talc-chlorite, or of rhodochrosite + kutnahorite in graded microlaminae, with 1-5% pyrite and 2-3% organic matter. At Naopa, magnetite locally takes the place of pyrite. Mn carbonates replace calcareous macro- and microfossils. Preservation of laminae suggests anoxic bottom waters during deposition. Paleodepth probably was 100 to 300 m, from sporadic beds with benthic fossils. The anoxic waters were probably rich in dissolved Mn, and may have been saturated with respect to rhodochrosite, leading to replacement of calcareous substrates. Dissolved iron in basin waters was kept low by pyrite precipitation.

  5. 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.

  6. Rheumatoid Arthritis Educational Video Series

    MedlinePlus

    ... Arthritis Educational Video Series Rheumatoid Arthritis Educational Video Series This series of five videos was designed to help you ... Educational Videos for Patients Rheumatoid Arthritis Educational Video Series Psoriatic Arthritis 101 2010 E.S.C.A.P. ...

  7. Rheumatoid Arthritis Educational Video Series

    MedlinePlus

    ... Rheumatoid Arthritis Educational Video Series Rheumatoid Arthritis Educational Video Series This series of five videos was designed ... Activity Role of Body Weight in Osteoarthritis Educational Videos for Patients Rheumatoid Arthritis Educational Video Series Psoriatic ...

  8. 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

  9. Sedimentary facies and sedimentary processes of the 2011 Tohoku-oki tsunami deposit with diversified grain size distribution

    NASA Astrophysics Data System (ADS)

    Yamada, M.; Fujino, S.; Goto, K.

    2012-12-01

    Most of the reported modern tsunami deposits are composed of sand, but gravelly tsunami deposits are rarely reported so far. While, gravely deposits that are considered as the possible paleotsunami deposits have often been identified in the geologic stratum. To expand our knowledge about diversity of tsunami deposits and provide criteria to identify tsunami deposits in the strata, we described a deposit with diversified grain size distribution of the 2011 Tohoku-oki tsunami. As well as describing the deposit, we also reconstructed its sedimentary processes. The height of the 2011 Tohoku-oki tsunami reached up to 28.1 m above sea level and inundated up to 1.8 km inland at the study site in Miyako city, Iwate prefecture, Japan. Tsunami deposit with diversified grain size distribution (silt-cobble) covered the lowland that had been used to paddy fields. The layered tsunami deposit is composed of pebble and cobble near the shore, whereas it is composed of sand and silt near the inundation limit, showing general fining landward trend. The thickness of the deposit is 1 m or more near the shore and generally thins inland to be a few centimeters. Separate from the layered deposits, many boulders that are composed of broken pieces of breakwaters, wave-dissipating blocks and volcanic rocks were scattered on the lowland. The transportation and deposition of the boulders and layered deposits at the study site is one of the rare cases in the sense that the wide range of sedimentary grains was deposited concurrently by a tsunami. Most boulders were deposited until 750 m from the shoreline, and the current velocities estimated from the boulder sizes show rapid declination at the point. The seaward stretched local scours around the larger boulders represent that they were not moved by the return flow. The gravelly tsunami deposit shows a sharp decline in thickness and grain size where many of the boulders were stopped. These indicate that deceleration in run-up flow caused rapid

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

    PubMed

    McNaughton; Rasmussen; Fletcher

    1999-07-01

    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.

  11. 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.

  12. 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

  13. 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

  14. 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

  15. 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

  16. 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

  17. Occurrences and distributions of branched alkylbenzenes in the Dongsheng sedimentary uranium ore deposits, China

    NASA Astrophysics Data System (ADS)

    Tuo, Jincai; Chen, Ru; Zhang, Mingfeng; Wang, Xianbin

    2010-11-01

    A series of branched alkylbenzene ranging from C 15 to C 19 with several isomers (2-5) at each carbon number were identified in sediments from the Dongsheng sedimentary uranium ore deposits, Ordos Basin, China. The distribution patterns of the branched alkylbenzenes show significant differences in the sample extracts. The branched alkylbenzenes from organic-rich argillites and coals range from C 15 to C 19 homologues, in which the C 17 or C 18 dominated. On the other hand, the C 19 branched alkylbenzenes dominated in the sandstone/siltstone extracts. The obvious differences of the branched alkylbenzene distributions between the uranium-host sandstones/siltstones and the interbedded barren organic-rich mudstones/coals probably indicate their potential use as biological markers associated with particular depositional environments and/or maturity diagenetic processes. Possible origins for these branched alkylbenzenes include interaction of simple aromatic compounds with, or cyclization and aromatization reactions of, these linear lipid precursors such as fatty acids, methyl alkanoates, wax esters or alkanes/alkenes that occur naturally in carbonaceous sediments. The possible simple aromatic compounds may include substituted benzenes, functionalized compounds such as phenols that are bound to kerogen at the benzyl position, and phenols that are decomposition products derived from aquatic and terrestrial sources. The distributions of methyl alkanoates and n-alkanes were found to be different between organic-rich mudstone/coal and sandstone/siltstone. From this result, it can be concluded that such differences of the alkylbenzene distributions were mainly resulting from the differences of organic precursors, although maturity effect and radiolytic alteration cannot be completely excluded.

  18. 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

  19. Sedimentary evolution and palaeogeography of mid-Jurassic deposits of the Central High Atlas, Morocco

    NASA Astrophysics Data System (ADS)

    Ait Addi, Abdellah; Chafiki, Driss

    2013-08-01

    In the axis of the Moroccan Central High Atlas rift basin, Toarcian-Middle Jurassic deposits, excepting the early Toarcian Tagoudite Formation, are represented by two formations - Agoudim and Tazigzaout - comprising clays, marls and limestones. On the margins of the basin, the lateral equivalents of these two formations are dolostone-dominated and show the lithological and environmental characteristics of the Bin El Ouidane Group recognized in the NW part of the Central High Atlas (Beni-Mellal/Azilal area). This group is overlain by clays and limestones of the Tillouguite Formation and by Bathonian red beds (silts, sandstones and conglomerates) of the Anemzi Formation. From the Toarcian to Aalenian (Agoudim Members I and II) the contrasting palaeogeographical evolution is marked by a relatively deep central basin bordered by shallow marine carbonates. The Aalenian-Lower Bajocian interval (Agoudim Member II) contains lenticular biodetritic limestones within hemipelagic deposits. These facies resulted from recurrent faulting (tectonic pulses), which was at the origin of the individualization of a series of ridges and depocentres within the High Atlas trough. During the Bajocian (Agoudim Members III and IV) the palaeogeography became homogeneous across the Central High Atlas and corresponded to a carbonate ramp with coral patch reefs. During the ?Late Bajocian (Tazigzaout Lower Member) a new palaeogeography developed with reappearance of the central depocentres. During the latest Bajocian-earliest Bathonian (Tazigzaout Upper Member) a very homogeneous carbonate ramp was again established. These times of uniform palaeogeography are interpreted as relative stable tectonic periods that were progressive stages leading to the ending of the Toarcian-Middle Jurassic sedimentary cycles in the Central High Atlas rift basin of Morocco.

  20. 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

  1. 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.

  2. Constraining Depositional Slope From Sedimentary Structures in Sandy Braided Streams

    NASA Astrophysics Data System (ADS)

    Lynds, R. M.; Mohrig, D.; Heller, P. L.

    2003-12-01

    Determination of paleoslopes in ancient fluvial systems has potentially broad application to quantitatively constraining the history of tectonics and paleoclimate in continental sequences. Our method for calculating paleoslopes for sandy braided streams is based upon a simple physical model that establishes depositional skin-frictional shear stresses from assemblages of sedimentary structures and their associated grain size distributions. The addition of a skin-frictional shear stress, with a geometrically determined form-drag shear stress results in a total boundary shear stress which is directly related to water-surface slope averaged over an appropriate spatial scale. In order to apply this model to ancient fluvial systems, it is necessary to measure the following: coarsest suspended sediment size, finest grain size carried in bed load, flow depth, dune height, and dune length. In the rock record, suspended load and bed load can be accurately assessed by well-preserved suspended load deposits ("low-energy" ripples) and bed load deposits (dune foresets). This model predicts an average slope for the North Loup River near Taylor, Nebraska (modern case study) of 2.7 x 10-3. The measured reach-averaged water surface slope for the same reach of the river is 1.37 x 10-3. We suggest that it is possible to calculate the depositional slope of a sandy fluvial system by a factor of approximately two. Additionally, preliminary application of this model to the Lower Jurassic Kayenta Formation throughout the Colorado Plateau provides a promising and consistent evaluation of paleoslope in an ancient and well-preserved, sandy braided stream deposit.

  3. 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

  4. 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.

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

    DOE PAGES

    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 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

  6. 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

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

    PubMed

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

    2013-05-01

    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. 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.

  9. 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

  10. 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.

  11. 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

  12. 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

  13. 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.

  14. 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.

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

    PubMed

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

    1990-01-18

    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.

  16. Sedimentary environment and facies of St Lucia Estuary Mouth, Zululand, South Africa

    NASA Astrophysics Data System (ADS)

    Wright, C. I.; Mason, T. R.

    The St. Lucia Estuary is situated on the subtropical, predominantly microtidal Zululand coast. Modern sedimentary environments within the estuary fall into three categories: (1) barrier environments; (2) abandoned channel environments; and (3) estuarine/lagoonal environments. The barrier-associated environment includes tidal inlet channel, inlet beach face, flood-tidal delta, ebb-tidal delta, spit, backspit and aeolian dune facies. The abandoned channel environment comprises washover fan, tidal creek tidal creek delta and back-barrier lagoon facies. The estuarine/lagoonal environment includes subtidal estuarine channel, side-attached bar, channel margin, mangrove fringe and channel island facies. Each sedimentary facies is characterised by sedimentary and biogenic structures, grain-size and sedimentary processes. Vertical facies sequences produced by inlet channel migration and lagoonal infilling are sufficiently distinct to be recognized in the geological record and are typical of a prograding shoreline.

  17. 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. PMID:24324274

  18. 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)

  19. 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).

  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. 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.

  2. 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

  3. 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

  4. 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.

  5. 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. PMID:20472452

  6. 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.

  7. 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.)

  8. 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

  9. SERI laser scanner system

    SciTech Connect

    Matson, R.J.; Cannon, T.W.

    1980-10-01

    A Laser Scanner System (LSS) produces a photoresponse map and can be used for the nondestructive detection of nonuniformities in the photoresponse of a semiconductor device. At SERI the photoresponse maps are used to identify solar cell faults including microcracks, metallization breaks, regions of poor contact between metallization and the underlying emitter surface, and variations in emitter sheet resistance. The SERI LSS is patterned after the LSS unit documented in the NBS Special Publication 400-24 A Laser Scanner for Semiconductor Devices by D.E. Sawyer and D.W. Berning. Assuming reader familiarity with the above publication, the modifications introduced by SERI are specified with the intention that the two reports can be used to reproduce the SERI LSS. The optical and electronic systems are reviewed, briefly discussing the significant items of each. The most notable difference between the two systems is the SERI substitution of commercially available state-of-the-art modular electronics for the discreet component circuitry used in the NBS LSS.

  10. 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

  11. 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

  12. Assessing sedimentary records of paleohurricane activity using modeled hurricane climatology

    NASA Astrophysics Data System (ADS)

    Woodruff, Jonathan D.; Donnelly, Jeffrey P.; Emanuel, Kerry; Lane, Philip

    2008-09-01

    Patterns of overwash deposition observed within back-barrier sediment archives can indicate past changes in tropical cyclone activity; however, it is necessary to evaluate the significance of observed trends in the context of the full range of variability under modern climate conditions. Here we present a method for assessing the statistical significance of patterns observed within a sedimentary hurricane-overwash reconstruction. To alleviate restrictions associated with the limited number of historical hurricanes affecting a specific site, we apply a recently published technique for generating a large number of synthetic storms using a coupled ocean-atmosphere hurricane model set to simulate modern climatology. Thousands of overwash records are generated for a site using a random draw of these synthetic hurricanes, a prescribed threshold for overwash, and a specified temporal resolution based on sedimentation rates observed at a particular site. As a test case we apply this Monte Carlo technique to a hurricane-induced overwash reconstruction developed from Laguna Playa Grande (LPG), a coastal lagoon located on the island of Vieques, Puerto Rico in the northeastern Caribbean. Apparent overwash rates in the LPG overwash record are observed to be four times lower between 2500 and 1000 years B.P. when compared to apparent overwash rates during the last 300 years. However, probability distributions based on Monte Carlo simulations indicate that as much as 65% of this drop can be explained by a reduction in the temporal resolution for older sediments due to a decrease in sedimentation rates. Periods of no apparent overwash activity at LPG between 2500 and 3600 years B.P. and 500-1000 years B.P. are exceptionally long and are unlikely to occur (above 99% confidence) under the current climate conditions. In addition, breaks in activity are difficult to produce even when the hurricane model is forced to a constant El Niño state. Results from this study continue to support

  13. 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.

  14. 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.

  15. 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,…

  16. 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…

  17. Basic Stuff Series.

    ERIC Educational Resources Information Center

    Bain, Linda, Ed.; And Others

    1981-01-01

    The Basic Stuff project is an effort to include more general concepts such as the effects of exercise, the learning of a new skill, and psychological factors influencing performance. The Basic Stuff Series attempts to summarize for teachers appropriate concepts and teaching methods. (JN)

  18. 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…

  19. 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…

  20. Time Series Database

    SciTech Connect

    Dugan, Jon M.

    2007-11-02

    TSDB is a Python module for storing large volumes of time series data. TSDB stores data in binary files indexed by a timestamp. Aggregation functions (such as rate, sum, avg, etc.) can be performed on the data, but data is never discarded. TSDB is presently best suited for SNMP data but new data types are easily added.

  1. 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…

  2. Little Herder Reading Series.

    ERIC Educational Resources Information Center

    Bureau of Indian Affairs (Dept. of Interior), Washington, DC.

    The Little Herder Reading Series is comprised of 4 volumes based on the life of a Navajo Indian girl. The books are written in English blank verse and describe many facets of Indian life. The volumes contain illustrations by Hoke Denetsosie which give a pictorial representation of the printed verse. The reading level is for the middle and upper…

  3. 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…

  4. 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

  5. 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.

  6. In-situ Detection of Squalane in Sedimentary Organic Matter Using Monoclonal Antibodies

    NASA Astrophysics Data System (ADS)

    Bailey, J. V.; Corsetti, F. A.; Moldowan, J. M.; Fago, F.; Caron, D.

    2008-12-01

    Sedimentary geolipids can serve as powerful tools for reconstructing ancient ecosystems, but only if investigators can demonstrate that the hydrocarbons are indigenous to their host rocks. The association of molecules with primary sedimentary fabrics could indicate a syngenetic relationship. However, traditional biomarker analyses require extraction from large quantities of powdered rock, confounding detailed spatial correlations. Biological studies commonly use antibodies as extremely sensitive molecular probes. When coupled with fluorescent labels, antibodies allow for the visual localization of molecules. Here we show that monoclonal antibodies that bind specifically to geolipid compounds can be used for in situ detection and labeling of such compounds in mineral-bound organic macerals. Monoclonal antibodies to squalene, produced for human health studies, also react with the geolipid, squalane. We show that squalene antibodies do not react with other common sedimentary hydrocarbons. We also show that squalane antibodies bind specifically to isolated organic-rich lamina in Eocene-age, squalane-containing rocks. These results suggest that squalane is confined to discrete organo-sedimentary fabrics within those rocks, providing evidence for its syngeneity. The chemical similarity of squalane to other sedimentary hydrocarbons hints at the potential for developing monoclonal antibodies to a variety of biomarkers that could then be localized in rocks, sediments, and extant cells.

  7. 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.

  8. Weathering of expansive sedimentary rock due to cycles of wetting and drying

    SciTech Connect

    Day, R.W. )

    1994-09-01

    There are several different mechanisms by which sedimentary rock can weather, such as: (1) Rebound: for cut areas, where the overburden has been removed by erosion or during mass-grading operations, the sedimentary rock will rebound due to the release in overburden pressure, the rebound can cause the opening or widening of cracks and joints; (2) Physical Weathering: sedimentary rock can be broken apart by the physical growth of plant roots or by the freezing of water in rock cracks or joints. Studies have also shown that precipitation of gypsum in rock pores, cracks, and joints can cause rock expansion and disintegration. Such conditions occur in arid climates where subsurface moisture evaporates at ground surface, precipitating the minerals in the rock pores. Acicular gypsum crystals have been observed to grow perpendicular to structures and are believed to exert the most force at their growing end (Hawkins and Pinces, 1987). Acicular gypsum growth has even been observed in massive sandstone, which resulted in significant heave (Hollingsworth and Grover, 1992); (3) Chemical Weathering: weathering of sedimentary rock can be due to oxidation, hydration of clay minerals, and the chemical alteration of the silt-size particles to clay. Factors affecting oxidation include the presence of moisture and oxygen (aerobic conditions), biological activity, acidic environment, and temperature (Hollingsworth and Grover, 1992). The purpose of this study was to investigate the weathering of expansive sedimentary rock due to cycles of wetting and drying at temperatures representative of field conditions.

  9. North Slope, Alaska: A case study of Sedimentary AeroMagnetics (SAM)

    SciTech Connect

    McConnell, T.J.

    1995-12-31

    Sedimentary AeroMagnetics (SAM) is the application of very high resolution aeromagnetic data to the exploration for hydrocarbons in the sedimentary section of a basin. Basically SAM provides very high spatial resolution of very low amplitude (<1 nT) anomalies originating from structures within the weakly magnetic sedimentary column. These sedimentary anomalies are superimposed upon the conventional high amplitude magnetic anomalies created by the crystalline basement. These low intensity anomalies generated from within the sediments are related to changes in the magnetic composition of the rocks. This can occur when rocks of differing magnetic susceptibilities are juxtaposed across a fault, or at a stratigraphic truncation. Fluid flow along faults, or at a stratigraphic truncation. Fluid flow along faults and fracture zones can also produce magnetization effects which can allow direct delineament of the fault or fracture zone. Stratigraphic units of weakly magnetic shale and sandstone also create subtle plateau effects in the magnetic amplitude maps. SAM data is a result of combining improvements in aeromagnetic data acquisition technology with new ideas on the design of the survey parameters. SAM surveys are generally flown at 200 - 800 meter line spacing with a terrain clearance of 60 - 150 meters. Data processing techniques are used which preserve the broad band frequency spectrum of the acquired data thereby allowing interpretation of the separate and distinct anomaly sources of the sedimentary column and of the crystalline basement.

  10. 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%).

  11. 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.

  12. Disaggregating times series data

    SciTech Connect

    Joubert, S.B.; Burr, T.; Scovel, J.C.

    1997-05-01

    This report describes our experiences with disaggregating time series data. Suppose we have gathered data every two seconds and want to guess the data at one-second intervals. Under certain assumptions, there are several reasonable disaggregation methods as well as several performance measures to judge their performance. Here we present results for both simulated and real data for two methods using several performance criteria.

  13. 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

  14. Large rivers in sedimentary basins: Morphology and form observed from satellite imagery

    NASA Astrophysics Data System (ADS)

    Weissmann, G. S.; Hartley, A. J.; Scuderi, L. A.; Nichols, G. J.; Davidson, S. K.

    2010-12-01

    Preservation of the deposits of big rivers, like any other river, can only occur where the river crosses an area of net aggradation in a sedimentary basin. Many of the world’s big rivers are systems that transfer sediment load from erosional realms to the sea, depositing fluvial successions only where there is accommodation on the coastal plain. However, many of the big rivers (e.g., Parana, Paraguay, Brahmaputra, Ganges, Indus, and Yukon Rivers) also cross continental sedimentary basins (e.g., sedimentary basins with minimal marine influence that lie inside continents) on their way to the oceans. We use satellite imagery to observe the large-scale morphology of big rivers in these continental sedimentary basins. As with other rivers, big rivers lose confinement of their valleys and form distributive fluvial systems (DFS) as they enter the continental sedimentary basins. Commonly, channel size decreases down-DFS, either through infiltration, bifurcation, or evaporation. Several active and/or old channels radiate outward from a DFS apex, and where the river is incised into its DFS, several paleochannel deposits are visible radiating outward from the DFS apex. Between and adjacent to channels, a significant amount of fine-grained sediment is deposited across the DFS surface, leaving high potential for preservation of floodplain deposits, even on large river DFS dominated by braided river systems. Commonly, the big rivers become the axial river in the sedimentary basin, continuing along strike of the basin. In this position, the river becomes confined between opposing DFS or between transverse DFS and the basin edge. In several examples, the river morphology changes upon reaching the sedimentary basin and across the DFS and this morphology may change once again at the toe of the DFS where the river takes the axial position in the basin. For example, the Brahamaputra River upstream from the sedimentary basin is a relatively narrow, single thread channel that is

  15. 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.

  16. 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.

  17. Marine sedimentary record of Meltwater Pulse 1a along the NW Barents Sea continental margin

    NASA Astrophysics Data System (ADS)

    Giulia Lucchi, Renata; Sagnotti, Leonardo; Camerlenghi, Angelo; Macrì, Patrizia; Rebesco, Michele; Pedrosa, Maria Teresa; Giorgetti, Giovanna

    2016-04-01

    The upper continental slope of the Storfjorden-Kveithola Trough Mouth Fans (NW Barents Sea) contains a several m-thick late Pleistocene sequence of plumites composed of laminated mud interbedded with sand/silt layers. Radiocarbon ages revealed that deposition occurred during about 130 years at a very high sedimentation rate of 3.4 cm a-1, at about 7 km from the present shelf break. Palaeomagnetic and rock magnetic analyses confirm the existence of a prominent, short-living sedimentary event. The plumites appear laterally continuous and were correlated with the sedimentary sequences described west of Svalbard and neighbouring glacial depositional systems representing a major event at regional scale appointed to correspond to the deep-sea sedimentary record of Meltwater Pulse-1a. We also present new sedimentological and geochemical insights, and multi-beam data adding information on the palaeoenvironmental characteristics during MWP-1a and ice sheet decay in the NW Barents Sea.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Detrital Zircon U-Pb Ages of River Sands from Taiwan: Implications for Sedimentary Provenance and Its Source Link with the East Chinese Mainland

    NASA Astrophysics Data System (ADS)

    Deng, K.; Yang, S.; Li, C.; Bi, L.; Chang, Y. P.

    2015-12-01

    In order to investigate the provenances of sedimentary rocks in Taiwan Island, we report the U-Pb geochronology of 630 concordant detrital zircons separated from the sandy sediments of the Zhuoshui River in west Taiwan and the Lanyang River in east Taiwan. In addition, 1472 published ages of detrital zircons from different rivers draining the east Chinese mainland are compiled to reveal the source-sink relationship between Taiwanese sedimentary rocks and east mainland. Detrital zircons from the two Taiwanese Rivers show seven major age groups of 100-200 Ma, 200-300 Ma, 360-550 Ma, 700-850 Ma, 0.9-1.1 Ga, 1.8-2.0 Ga and 2.4-2.6 Ga, which correspond well with major tectonic and magmatic events in east mainland. Nevertheless, the U-Pb age distributions have significant difference between east and west Taiwan terranes, showing high proportion of Phanerozoic zircons in east Taiwan and more complex age population and more Precambrian zircons in west Taiwan. This reveals obviously different sedimentary evolution between east and west Taiwan terranes. A series of methods (kernel density estimation plot, cumulative probability plot, overlap and similarity and a simple provenance model) are carried out to compare the U-Pb age distributions between Taiwan and east Chinese mainland, hence the source-sink relationship between them can be investigated. The Eocene-late Oligocene sequences of the Hsuehshan Range and the Miocene turbidity sequences of the east Central Range in east Taiwan are mainly sourced from the west Cathaysia Block (contributing about 81% of total zircon age population). The Yangtze Block (about 43%) and the North China Block (about 34%) may be the dominant provenances of the Eocene-Pleistocene sequences in west Taiwan.

  4. 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.

  5. 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.

  6. 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

  7. 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. PMID:15833644

  8. 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.

  9. 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

  10. Subdivision of thick sedimentary units into layers for simulation of groundwater flow.

    USGS Publications Warehouse

    Weiss, J.S.; Williamson, A.K.

    1985-01-01

    Subdividing thick sedimentary units into model layers based solely on stratigraphy can lead to serious violation of groundwater flow modeling restraints and produce erroneous results. Borehole geophysical data can be used to suggest relative permeabilities and delineate model layers that are more likely to have uniform hydraulic properties than layers delineated by stratigraphic definitions alone. The uniformity within layers emphasizes the permeability contrast between layers, thereby allowing a quasi three-dimensional approach. These methods are applied to the thick sedimentary units of the Gulf Coastal Plain, USA.-from Authors

  11. 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

  12. 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.

  13. 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.

  14. Aliphatic biomarkers and their signal from two hydrogeochemically differing sedimentary environments of the Tertiary Krepoljin Coal Basin (Serbia)

    NASA Astrophysics Data System (ADS)

    Dević, Gordana J.; Popovic, Zoran

    2010-05-01

    The sediments of the coal-bearing series of the Tertiary Krepoljin Brown Coal Basin have been investigated and presented in this manuscript. The samples of the intercalated mixed sediments (pieces of coal in clays, sandstones and shales) originate from two hydrogeochemically differing sedimentary environments: the illite-montmorillonitic (IM), and the calcitic (Ct) environment. The characteristics of the early diagenetic processes which influenced the composition of the organic matter of this sediment were assessed by the statistical correlation analysis and multivariate principal component analysis. The precursor material of higher plants gymnosperms had a significant influence on the overall organic matter of mixed sediments in both hydrochemical environments. A weak effect of N/C ratios on the specific diagenetic transformations of hopanoid molecules is noticed in the samples of the calcite environment. Sterane maturation transformations are not marked as significant for the samples of mixed sediments by the component analysis. The samples of I-M environments show a strong inhibitory effect on the processes of diastereoisomerization.

  15. 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).

  16. 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.

  17. Biogeochemical controls on reaction of sedimentary organic matter and aqueous sulfides in holocene sediments of Mud Lake, Florida

    NASA Astrophysics Data System (ADS)

    Filley, Timothy R.; Freeman, Katherine H.; Wilkin, Rick T.; Hatcher, Patrick G.

    2002-03-01

    The distribution and quantity of organic sulfur and iron sulfur species were determined in the Holocene sediments from Mud Lake, Florida. The sediments of this shallow, sinkhole lake are characterized by high sulfur and organic carbon contents as well as active sulfate reduction. They record a shift from a basal peat (below 2 m) comprised of water lily-dominated organic matter to the present cyanobacterial/algal-dominated lake deposit (upper 1 m). This shift in depositional environment and subsequent organic matter source was accompanied by variation in the amount of reactive iron delivered to the sediments, which in turn influenced the type and extent of organic matter sulfurization. Extractable intramolecular organic sulfur is principally found as C 25 highly branched isoprenoid (HBI) thiolanes. Extractable polysulfide-linked lipids, determined by selective chemical cleavage with MeLi/MeI and analyzed as methylthioethers (MTE), are dominated by n-alkanes with sulfur attachments at position 1 and 2, as well as lower amounts of C 25 HBI-MTE. The δ 13C values and carbon-chain length distribution of both series of n-alkylMTE indicate that they are derived from distinct biological precursors. Among the n-alkylMTE with sulfur attachment at position 1 there are three homologous series: one saturated and two with both cis and trans enethiol isomers. The identification of the enethiol in the sulfur-linked macromolecules indicates that n-alkylaldehydes are precursors lipids. The intervals of high concentration of bulk organic sulfur and sulfurized lipids coincide with the intervals of high mineral sulfur content (acid volatile sulfide and chromium reducible sulfur). We suggest that the main control on the enhanced addition of sulfur to the organic matter in Mud Lake was the increased formation of polysulfides during the reduction of iron hydroxides and the subsequent reaction of those polysulfides with mildly oxidized sedimentary organic matter.

  18. 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.

  19. Sedimentary pools of phosphorus in the eutrophic Tamar estuary (SW England).

    PubMed

    Monbet, Phil; McKelvie, Ian D; Worsfold, Paul J

    2010-01-01

    The speciation of phosphorus in Tamar estuary sediment has been determined at eight stations from Gunnislake (riverine end-member) to Torpoint (marine end-member) using the SEDEX (sedimentary extraction) sequential extraction scheme. The seasonal variability of total phosphorus and each of the five fractions is discussed. Total phosphorus, in the range 26-51 micromol g(-1), was stored in the relatively labile fractions, particularly in the iron oxide fraction. The well oxygenated waters of the macrotidal Tamar estuary ensure that the surface sediment layer remains oxic, providing an effective barrier that retains dissolved reactive phosphorus (DRP) within the sedimentary iron oxide fraction and prevents phosphorus migration from the sediment to the water column. The exchangeable and organic phosphorus sedimentary pools, although small, are therefore the main potential sources of phosphorus release to the water column. In particular, this study shows that exchangeable phosphorus and dissolved organic phosphorus (DOP) in the pore water are intimately linked. Finally, the distribution of phosphorus in the estuary is strongly influenced by particle morphology, with most of the sedimentary phosphorus forms exhibiting significant positive correlations with the percent of each grain size.

  20. Folded onlap geometries: implications for recognition of syn-sedimentary folds

    NASA Astrophysics Data System (ADS)

    Casas-Sainz, Antonio M.; Soto-Marín, Ruth; González, Ángel; José Villalaín, Juan

    2005-09-01

    Growth strata are usually analysed from geological maps, outcrop geometry or seismic sections. Many growth folds have been defined from geological maps, especially in areas where plunging structures allow the syn-tectonic sequence to be displayed at the surface. The geometrical arrangement of these syn-tectonic sequences can also be defined from the relationships between pre-growth and growth strata, as obtained from geological maps. In this paper, from theoretical models and natural examples from the southern Pyrenees, we argue that some cartographic patterns of strata associated with variably plunging folds, traditionally ascribed to syn-tectonic sedimentation with thinning of sedimentary units toward the anticlinal hinge zone, can be explained as completely post-sedimentary folds of sedimentary units lapping onto an inclined bedding surface, and linked to basin margin, or downlap geometries on the basin floor. We conclude that 3-D analysis of syn-tectonic structures, combining data from independent sources (i.e. geological maps and seismic reflection profiles) is essential to determine relationships between sedimentary units and structures.

  1. 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.

  2. 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.

  3. 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 (Grotzinger et al., 2015). From ChemCam LIBS chemical analyses, this suite of sedimentary rocks has an overall mean K2O abundance that is more than five 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

    2016-08-01

    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.

  9. 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.

  10. Composition and sources of sedimentary organic matter in the deep Eastern Mediterranean Sea

    NASA Astrophysics Data System (ADS)

    Pedrosa-Pàmies, R.; Parinos, C.; Sanchez-Vidal, A.; Gogou, A.; Calafat, A.; Canals, M.; Bouloubassi, I.; Lampadariou, N.

    2015-07-01

    Surface sediments collected from deep slopes and basins (1018-4087 m depth) of the oligotrophic Eastern Mediterranean Sea have been analysed for bulk elemental and isotopic composition of organic carbon, total nitrogen and selected lipid biomarkers, jointly with grain size distribution and other geochemical proxies. The distribution and sources of sedimentary organic matter (OM) have been subsequently assessed and general environmental variables, such as water depth and currents, have been examined as causative factors of deep-sea sediment characteristics. Lithogenic and biogenic carbonates are the dominant sedimentary fractions, while both bulk and molecular organic tracers reflect a mixed contribution from autochthonous and allochthonous sources for the sedimentary OM, as indicated by relatively degraded marine OM, terrestrial plant waxes and anthropogenic OM including degraded petroleum by-products, respectively. Wide regional variations have been observed amongst the studied proxies, which reflect the multiple factors controlling sedimentation in the deep Eastern Mediterranean Sea. Our findings highlight the role of deep Eastern Mediterranean basins as depocentres of organic-rich fine-grained sediments (mean 5.4 ± 2.4 μm), with OM accumulation and burial due to aggregation mechanisms and hydrodynamic sorting. A multi-proxy approach is hired to investigate the biogeochemical composition of sediment samples, which sheds new light on the sources and transport mechanisms along with the impact of preservation vs. diagenetic processes on the composition of sedimentary OM in the deep basins of the oligotrophic Eastern Mediterranean Sea.

  11. 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.

  12. Comparison of dissolution under oxic acid drainage conditions for eight sedimentary and hydrothermal pyrite samples

    NASA Astrophysics Data System (ADS)

    Liu, Ran; Wolfe, Amy L.; Dzombak, David A.; Stewart, Brian W.; Capo, Rosemary C.

    2008-11-01

    The abiotic oxidative dissolution behaviors of eight natural pyrite samples, five sedimentary and three hydrothermal, from various geological environments were compared under oxic conditions at pH 3 and 6 in a highly controlled batch reactor dissolution system. The three sedimentary pyrite samples associated with coal had greater specific surface areas and also exhibited greater apparent dissolution rates and extent than the other two sedimentary and three hydrothermal samples under both pH conditions. However, after normalizing for surface area, the dissolution rate constants for the different pyrite samples were similar; the greatest difference was between the two non-coal sedimentary pyrite samples. Pyrite morphology and the presence of trace metals could contribute to the differences in dissolution behavior as reflected in the normalized dissolution rates. The sulfur:iron ratio observed in the aqueous solution at pH 3 increased with time, but was always less than 2.0 (predicted from the stoichiometry of dissolution) for all the pyrite samples during the 24-h experimental duration. This can be explained by the disproportionation dissociation of thiosulfate, an initial product of pyrite dissolution, to elemental sulfur and sulfate which does not occur in a 1:1 ratio. The results of this work indicate the importance of extracting and using the specific pyrite(s) relevant to particular mining areas in order to understand pyrite dissolution rates and the influence of environmental conditions on those rates.

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

    PubMed

    Garrels, R M; Mackenzie, F T

    1969-02-01

    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. PMID:17750892

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

    PubMed

    Garrels, R M; Mackenzie, F T

    1969-02-01

    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.

  15. 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.

  16. 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.

  17. 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

  18. 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

  19. 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.

  20. 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

  1. 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?

  2. 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.

  3. 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.

  4. 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.

  5. Ordinal analysis of time series

    NASA Astrophysics Data System (ADS)

    Keller, K.; Sinn, M.

    2005-10-01

    In order to develop fast and robust methods for extracting qualitative information from non-linear time series, Bandt and Pompe have proposed to consider time series from the pure ordinal viewpoint. On the basis of counting ordinal patterns, which describe the up-and-down in a time series, they have introduced the concept of permutation entropy for quantifying the complexity of a system behind a time series. The permutation entropy only provides one detail of the ordinal structure of a time series. Here we present a method for extracting the whole ordinal information.

  6. 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

  7. 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

  8. The Surtsey Magma Series

    NASA Astrophysics Data System (ADS)

    Ian Schipper, C.; Jakobsson, Sveinn P.; White, James D. L.; Michael Palin, J.; Bush-Marcinowski, Tim

    2015-06-01

    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.

  9. The Surtsey Magma Series.

    PubMed

    Schipper, C Ian; Jakobsson, Sveinn P; White, James D L; Michael Palin, J; Bush-Marcinowski, Tim

    2015-06-26

    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 50(th) 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.

  10. The Surtsey Magma Series.

    PubMed

    Schipper, C Ian; 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 50(th) 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

  11. Nonketotic hyperglycinemia case series

    PubMed Central

    Iqbal, Mehtab; Prasad, Manish; Mordekar, Santosh R.

    2015-01-01

    To present three cases who presented with neonatal hiccups and who were later diagnosed with nonketotic hyperglycinemia (NKH). Case series. We present three babies who presented in neonatal life with hiccups who later were diagnosed with NKH. Two babies presented on the 2nd day of life with hypotonia, poor feeding, and abnormal movements including jitteriness, hiccups, and twitching. The third baby only had transient hiccups lasting for a couple of days in the 1st week of life but later presented at 3 months of age with poor feeding, drowsiness, and jerky movements. All three cases needed extensive investigations before reaching the diagnosis including metabolic screen, lumbar puncture, electroencephalography, and computed tomography/magnetic resonance imaging. The first two babies needed intubation on their 2nd day of life because of apneas in whom later, the care was withdrawn after reaching the diagnosis of NKH because of poor prognosis. The third baby was discharged home on oral dextromethorphan and ketogenic diet. We discuss the importance of early recognition of symptoms (frequent hiccups) and investigation needed to reach the diagnosis early as it helps in making decision to either carry on treatment or withdraw care because of poor prognosis. It also helps in genetic counseling and prenatal diagnosis can be offered at the subsequent pregnancy. PMID:26962342

  12. The recent marine sedimentary record of Baranof Island, Southeast Alaska - implications for paleoclimate reconstructions

    NASA Astrophysics Data System (ADS)

    Addison, J. A.; Finney, B. P.; Jaeger, J. M.; Stoner, J. S.; Norris, R. D.; Hangsterfer, A.

    2011-12-01

    Modern and paleoclimate studies suggest a correlation between Pacific decadal climate variability and marine ecosystem productivity, but are generally limited by either short periods of observation or low temporal resolution. Long, annually resolved paleoclimate time-series data are thus critical for assessing this correlation and understanding the full range of Pacific climate variability and its impacts. Baranof Island is located in the Alexander Archipelago of Southeast Alaska, and contains many temperate ice-free fjords with shallow sills that enhance organic matter preservation by restricting oxygenation of bottom waters. Multicore samples EW0408-32MC and 43MC were recovered from two fjords on Baranof Island, and analyzed to determine how recent sedimentation patterns relate to the instrument record as a first step towards reconstructing high-latitude Pacific climate at annual timescales. A combination of radiometric 137Cs and excess 210Pb geochronometry, 3D computerized tomography (CT), and high-resolution Avaatech scanning XRF geochemical analyses were used to investigate this relationship. Scanning XRF data were collected every 2 mm on core 32MC, while 43MC was measured at 0.2 mm intervals. Core 32MC is composed of a diffusely laminated to bioturbated clay with a maximum apparent steady-state sedimentation rate of ~5±1 mm/yr, while core 43MC is a strongly laminated diatom ooze with a maximum apparent sedimentation rate of ~6±0.5 mm/yr. Using conservative estimates of accumulation to assess basal ages of the cores yields approximately ~AD 1930 for 32MC, and ~AD 1900 for 43MC. Scanning XRF centered natural log-ratio transformed [clr] element intensities indicate 32MC is controlled by a balance between detrital (Al, Si, K, Ti, Fe, and Ca) and biogenic components (S and Br), and isolated peaks in clr Ca data correspond with CT-visible shell debris. Core 43MC is more complex, with both XRF and CT scans indicating four distinct lithologies: (i) millimeter

  13. 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

  14. 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.

  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. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Photogeologic linears as reflecting hydrogeologic regimes of a great sedimentary basin

    SciTech Connect

    Astakhov, V.I.

    1996-07-01

    The geological significance of linears of various length derived from satellite and airphoto images in the West Siberian sedimentary basin is discussed. A geological signal from deep-seated structures depends on length bands of linears populations. The useful length bands vary depending on the position of a test-site within the basin. The best match between the landscape and deep-seated structural features is obtained in the central part of the basin with great vertical gradients of fluid pressure. The strong hydraulic tensity of a sediment cover is thought to be a prerequisite for minor deep-seated fractures to penetrate through the sedimentary column and distort the normal planetary orientation of short linears on the surface. The hydrogeologic factor is summoned to improve the oscillatory mechanism of fracture propagation.

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. Sixty Years of Anisotropy of Magnetic Susceptibility in deformed sedimentary rocks

    NASA Astrophysics Data System (ADS)

    Pares, Josep

    2015-02-01

    The use of the Anisotropy of Magnetic Susceptibility (AMS) has become a rather common practice in Earth Sciences since the pioneer note by Graham (1954). The versatility of the technique, and the rapidness in obtaining and processing AMS data largely improved in the past thirty years, and has generated a wealth of literature, notably on mudrock fabrics. The assessment of the current trends in magnetic fabric studies reveals that AMS has one of its largest potential in sedimentary rocks from structural settings where the ductile component of deformation is cryptic or hindered by the brittle component. Abundant evidence provided by AMS data reveal that deformation extents beyond the deformation or cleavage front in contractional settings, including fold-and-thrust belts and active accretionary prisms, configuring magnetic fabrics as a standard method for fabric quantification in deformed sedimentary rocks.

  6. 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.

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

    PubMed

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

    2014-01-01

    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. PMID:24576990

  8. 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

  9. Analysis of well logging methods in volcanic and volcano sedimentary rocks from Pina petroleum field

    SciTech Connect

    Rodriquez, N.

    1996-09-01

    Petrophysical, petrological and geophysical methods have been applied to prospecting and well logging for several petroleum fields in Cuba. The most common reservoir in these fields are carbonate rocks. However, the Pina field, in the Central region of the island, distinguishes itself by the good quality of the oil and the volcano sedimentary and volcanic character of the reservoirs. These rocks have peculiar geophysical responses, which is why the study of these methods and the development of the interpretation methods is very important. Integrated geological and geophysical information was necessary during the drilling of wells in the Pina field in order to evaluate the hydrocarbon potential. GEONUC code permits us to use different ways to solve questions about interpretation of well logging in the volcanic sedimentary rocks. This code gives us the opportunity to analyze complex methods.

  10. The southern Washington Cascades conductor - a previously unrecognized thick sedimentary sequence?

    USGS Publications Warehouse

    Stanley, W.D.; Gwilliam, W.J.; Latham, G.; Westhusing, K.

    1992-01-01

    Geophysical studies in the southern Washington Cascades have outlined a possible, previously unrecognized sequence of sedimentary rocks. These postulated sedimentary units are interpreted to correspond to at least the upper section of a low-resistivity (high-conductivity) assemblage of rocks at depths of 1-10 km and with thicknesses up to 15 km that called the southern Washington Cascades conductor. Structure on the upper surface of this conductive assemblage correlates in some places with anticlines that bring Tertiary marine rocks near the surface. The geometry of the conductive rocks consists of a east-dipping, low-angle wedge that thickens to the north and with an undulating upper surface corresponding to the anticlines. Geothermal fluids may be a contributing factor to low resistivities in the deeper parts of the conductive section. -from Authors

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

    PubMed

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

    1994-05-19

    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.

  12. 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.

  13. 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.

  14. 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.

  15. [Comparative characteristics of the numbers of microorganisms in soils and their basement sedimentary rocks].

    PubMed

    Zviagintsev, D G; Khlebnikova, G M; Gorin, S E

    1979-01-01

    Comparative studies on the quantitative composition of microorganisms in soils and basement sedimentary rocks have shown that the latter are rich in microorganisms. The number of microorganisms in basement grounds changes with time, thus indicating their activity. The qualitative composition is poor. At the same time, the total quantity of microorganisms in basement layers is equal to that in soil. Basement layers contain 10 times more microorganisms than eutrophic water reservoirs and 1000 times more than oligotrophic water reservoirs.

  16. Darcy flow in heterogeneous porous media: relevance at sedimentary basin scale

    NASA Astrophysics Data System (ADS)

    Souche, Alban; Dabrowski, Marcin; Krotkiewski, Marcin

    2010-05-01

    Understanding heat transfer mechanisms in sedimentary rocks is important for recovering thermal history of sedimentary basins. Fluid flow may play a significant role by advecting heat within porous rocks of the basin. In extensional continental setting associated with stretching and thinning of the lithosphere, geothermal gradient below sedimentary basins may rise and contribute to the onset of thermal convection. Such process can be approximated by Darcy flow through porous media where thermal expansion introduces a gravitational instability between lighter hot fluids at the bottom and denser cold fluids at the top of the basin. However, the convection in such setting is inhibited by closing of the porosity with depth, which leads to limited amount of heat carrying fluids and a reduced permeability. We address this problem numerically by modeling Darcy's equations. To assess the accuracy of the pressure and velocity field in media with strongly varying permeability we compared two different numerical methods, 1) the standard finite element formulation with different order of elements (quadratic-pressure and linear-temperature) and 2) the mixed finite element formulation. An additional challenge in this study is to treat carefully the advection by choosing an appropriate numerical scheme. We used the method of characteristics with different flow integration, the Euler's and the 4th order Runge-Kutta's scheme, to avoid artificial diffusion that may significantly pollute the numerical solution. Results obtained for a homogeneous porous medium correspond to the analytical solution of the scaling between the Nusselt and Rayleigh numbers. We apply the tested model to investigate numerically the pattern of convection in heterogeneous porous rocks. We analyze the first-order characteristics and the limits of the convection in sedimentary basins under such conditions.

  17. 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

  18. Visualizing the sedimentary response through the orogenic cycle using multi-dimensional scaling

    NASA Astrophysics Data System (ADS)

    Spencer, C. J.; Kirkland, C.

    2015-12-01

    Changing patterns in detrital provenance through time have the ability to resolve salient features of an orogenic cycle. Such changes in the age spectrum of detrital minerals can be attributed to fluctuations in the geodynamic regime (e.g. opening of seaways, initiation of subduction and arc magmatism, and transition from subduction to collisional tectonics with arrival of exotic crustal material). These processes manifest themselves through a variety of sedimentary responses due to basin formation, transition from rift to drift sedimentation, or inversion and basement unroofing. This generally is charted by the presence of older detrital zircon populations during basement unroofing events and is followed by a successive younging in the detrital zircon age signature either through arrival of young island arc terranes or the progression of subduction magmatism along a continental margin. The sedimentary response to the aforementioned geodynamic environment can be visualized using a multi-dimensional scaling approach to detrital zircon age spectra. This statistical tool characterizes the "dissimilarity" of age spectra of the various sedimentary successions, but importantly also charts this measure through time. We present three case studies in which multi-dimensional scaling reveals additional useful information on the style of basin evolution within the orogenic cycle. The Albany-Fraser Orogeny in Western Australia and Grenville Orogeny (sensu stricto) in Laurentia demonstrate clear patterns in which detrital zircon age spectra become more dissimilar with time. In stark contrast, sedimentary successions from the Meso- to Neoproterozoic North Atlantic Region reveal no consistent pattern. Rather, the North Atlantic Region reflects a signature consistent with significant zircon age communication due to a distal position from an orogenic front, oblique translation of terranes, and complexity of the continental margin. This statistical approach provides a mechanism to

  19. 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.

  20. Composition and sources of sedimentary organic matter in the deep eastern Mediterranean Sea

    NASA Astrophysics Data System (ADS)

    Pedrosa-Pàmies, R.; Parinos, C.; Sanchez-Vidal, A.; Gogou, A.; Calafat, A.; Canals, M.; Bouloubassi, I.; Lampadariou, N.

    2015-12-01

    Surface sediments collected from deep slopes and basins (1018-4087 m depth) of the oligotrophic eastern Mediterranean Sea have been analysed for bulk elemental and isotopic composition of organic carbon, total nitrogen and selected lipid biomarkers, jointly with grain size distribution and other geochemical proxies. The distribution and sources of sedimentary organic matter (OM) have been subsequently assessed and general environmental variables, such as water column depth and physical circulation patterns, have been examined as causative factors of deep-sea sediment characteristics. Lithogenic and biogenic carbonates are the dominant sedimentary fractions, accounting for up to 85.4 and 66.5 % of the total weight respectively. The low OC and TN contents in the surface sediments of the study area, which ranged from 0.15 to 1.15 % and 0.06 to 0.11 % respectively, reflect the oligotrophic character of the eastern Mediterranean Sea. Both bulk and molecular organic tracers reflect a mixed contribution from autochthonous and allochthonous sources for the sedimentary OM, as indicated by relatively degraded marine OM, terrestrial plant waxes and anthropogenic OM (e.g. degraded petroleum by-products) respectively. Wide regional variations have been observed amongst the studied proxies, which reflect the multiple factors controlling sedimentation in the deep eastern Mediterranean Sea. Our findings highlight the role of deep eastern Mediterranean basins as depocentres of organic-rich fine-grained sediments (mean 5.4 ± 2.4 μm), with OM accumulation and burial being attributed to aggregation mechanisms and hydrodynamic sorting. A multi-proxy approach is applied aiming to investigate the biogeochemical composition of sediment samples, which sheds new light on the sources and transport mechanisms along with the impact of preservation vs. diagenetic processes on the composition of sedimentary OM in the deep basins of the oligotrophic eastern Mediterranean Sea.

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. Mesozoic sedimentary rocks and depositional facies, Vizcaino-Cedros Area, Baja California, Mexico

    SciTech Connect

    Boles, J.R.

    1986-04-01

    Mesozoic sedimentary rocks in the Vizcaino-Cedros area constitute a 135-m.y. history of arc-related marine sedimentation with a cumulative thickness of 14 km. The Upper Triassic San Hipolito Formation is the oldest sedimentary unit in the region, and is recognized only on the Vizcaino Peninsula. The formation depositionally overlies an ophiolite sequence and consists of 2.4 km of tuffaceous sediment including a limestone megabreccia. The upper two-thirds of the sequence in the type section is now believed to be of Early Jurassic age. On Cedros Island, the basal sedimentary rocks are 1.2 km of the Lower Jurassic Gran Canon Formation. This richly tuffaceous unit depositionally overlies both ophiolite and arc volcanics. Conformably overlying the Gran Canon on Cedros Island is the Coloradito Formation, a spectacular sedimentary olistostrome up to 0.4 km thick, containing Triassic and late Paleozoic metasedimentary blocks. This formation record the first evidence of continental detritus in the region. Conformably overlying the Coloradito and, in part, stratigraphically equivalent to it on Cedros is 0.4 km of volcanogenic-metasedimentary conglomerate designated the Eugenia Formation. The Eugenia is much thicker (to 2.7 km) and widespread on Vizcaino where it unconformably overlies the San Hipolito Formation. On Vizcaino, the lower Eugenia (Upper Jurassic) includes spectacular volcanic debris flows interbedded with sandstone, but it is transitional upward into finer facies with increasing plutonic detritus. Time equivalent to the upper Eugenia and locally deposited on tonalite and volcanics is the Lower Cretaceous Asunction Formation (0.8 km thick). This sequence includes calcareous coarse breccias of serpentinized gabbros and tonalite.

  7. 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.

  8. 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.

  9. 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

  10. Spatial stochastic modeling of sedimentary formations to assess CO2 storage potential.

    PubMed

    Popova, Olga H; Small, Mitchell J; McCoy, Sean T; Thomas, A C; Rose, Stephen; Karimi, Bobak; Carter, Kristin; Goodman, Angela

    2014-06-01

    Carbon capture and sequestration (CCS) is a technology that provides a near-term solution to reduce anthropogenic CO2 emissions to the atmosphere and reduce our impact on the climate system. Assessments of carbon sequestration resources that have been made for North America using existing methodologies likely underestimate uncertainty and variability in the reservoir parameters. This paper describes a geostatistical model developed to estimate the CO2 storage resource in sedimentary formations. The proposed stochastic model accounts for the spatial distribution of reservoir properties and is implemented in a case study of the Oriskany Formation of the Appalachian sedimentary basin. Results indicate that the CO2 storage resource for the Pennsylvania part of the Oriskany Formation has substantial spatial variation due to heterogeneity of formation properties and basin geology leading to significant uncertainty in the storage assessment. The Oriskany Formation sequestration resource estimate in Pennsylvania calculated with the effective efficiency factor, E=5%, ranges from 0.15 to 1.01 gigatonnes (Gt) with a mean value of 0.52 Gt of CO2 (E=5%). The methodology is generalizable to other sedimentary formations in which site-specific trend analyses and statistical models are developed to estimate the CO2 sequestration storage capacity and its uncertainty. More precise CO2 storage resource estimates will provide better recommendations for government and industry leaders and inform their decisions on which greenhouse gas mitigation measures are best fit for their regions.

  11. 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.

  12. 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.

  13. Dechlorinating microorganisms in a sedimentary rock matrix contaminated with a mixture of VOCs.

    PubMed

    Lima, Gláucia; Parker, Beth; Meyer, Jessica

    2012-06-01

    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.

  14. Factors influencing the biogeochemistry of sedimentary carbon and phosphorus in the Sacramento-San Joaquin Delta

    USGS Publications Warehouse

    Nilsen, E.B.; Delaney, M.L.

    2005-01-01

    This study characterizes organic carbon (Corganic) and phosphorus (P) geochemistry in surface sediments of the Sacramento-San Joaquin Delta, California. Sediment cores were collected from five sites on a sample transect from the edge of the San Francisco Bay eastward to the freshwater Consumnes River. The top 8 cm of each core were analyzed (in 1-cm intervals) for Corganic, four P fractions, and redox-sensitive trace metals (uranium and manganese). Sedimentary Corganic concentrations and Corganic:P ratios decreased, while reactive P concentrations increased moving inland in the Delta. The fraction of total P represented by organic P increased inland, while that of authigenic P was higher bayward than inland reflecting increased diagenetic alteration of organic matter toward the bayward end of the transect. The redox indicator metals are consistent with decreasing sedimentary suboxia inland. The distribution of P fractions and C:P ratios reflect the presence of relatively labile organic matter in upstream surface sediments. Sediment C and P geochemistry is influenced by site-specific particulate organic matter sources, the sorptive power of the sedimentary material present, physical forcing, and early diagenetic transformations presumably driven by Corganic oxidation. ?? 2005 Estuarine Research Federation.

  15. Dechlorinating microorganisms in a sedimentary rock matrix contaminated with a mixture of VOCs.

    PubMed

    Lima, Gláucia; Parker, Beth; Meyer, Jessica

    2012-06-01

    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. PMID:22612587

  16. 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.

  17. 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.

  18. 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.

  19. 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.

    2015-01-01

    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.

  20. 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.

  1. An integrated insight into the response of sedimentary microbial communities to heavy metal contamination.

    PubMed

    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

  2. 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

  3. 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.

  4. An integrated insight into the response of sedimentary microbial communities to heavy metal contamination.

    PubMed

    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.

  5. 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.

  6. 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.

  7. Hydrothermal circulation in an anisotropic sedimentary basin: Application to the Okinawa back arc basin

    SciTech Connect

    Genthon, P.; Rabinowicz, M. ); Foucher, J.P.; Sibuet, J.C. )

    1990-11-10

    The authors explore the pattern of two-dimensional convection in an highly anisotropical porous medium. This physical situation is relevant to passive margin sedimentary basins consisting of interbedded coarse-grained pervious and shale matrix. They show that permeability anisotropies of the order of 10{sup 2}-10{sup 4} allow for long convective cells, of aspect ratio greater than 10, but that a combination of this parameter with a slight slope of the order of a few percent of the sedimentary layers is required to stabilize these long cells. As an example, they present the Okinawa basin, an active submarine back arc basin, with a sedimentary thickness of about 2 km and a heat flow profile across this basin, varying from 32 to 232 mWm{sup {minus}2} over a distance of 30 km. It is shown that this heat flow variation is difficult to explain with conductive mechanisms only but is well reproduced by different convective models relying on permeability anisotropy plus slope. Although the insufficient thermal and structural constraints did not allow them to build a unique model, the whole set of possible fits to the heat flow data may restrict the mean hydraulic parameters of the basin. A vertical permeability of a few tens of milidarcy and an anisotropy greater than 100 are required to produce the expected stable and active large-scale circulation. It is suggested in conclusion that this type of circulation might be active in oil- or oil-forming element migration.

  8. 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.

  9. 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.

  10. 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

    2015-01-01

    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

  11. Identification of a late Quaternary alluvial-aeolian sedimentary sequence in the Sichuan Basin, China

    NASA Astrophysics Data System (ADS)

    Feng, Jin-Liang; Ju, Jian-Ting; Chen, Feng; Hu, Zhao-Guo; Zhao, Xiang; Gao, Shao-Peng

    2016-03-01

    The late Quaternary sedimentary sequence in the northwestern part of the Sichuan Basin consists of five lithological units and with increasing depth include the: Chengdu Clay; Brown Clay; Red Clay; Sandy Silt; and basal Muddy Gravel. The genesis, provenance and age of the sediments, as well as the possible presence of hiatuses within this sequence are debated. Measurements of grain-size, magnetic susceptibility, quartz content, quartz δ18O values, element composition, and Sr-Nd isotopic concentrations of samples from a typical sedimentary sequence in the area provides new insights into the genesis and history of the sequence. The new data confirm that the sediments in study site are alluvial-aeolian in origin, with basal alluvial deposits overlain by aeolian deposits. Like the uppermost Chengdu Clay, the underlying Brown Clay and Red Clay are aeolian in origin. In contrast, the Silty Sand, like the basal Muddy Gravel, is an alluvial deposit and not an aeolian deposit as previously thought. Moreover, the succession of the aeolian deposits very likely contains two significant sedimentary hiatuses. Sedimentological analysis demonstrates that the source materials for the aeolian deposits in the northwestern part of the Sichuan Basin and those on the eastern Tibetan Plateau are different. Furthermore, the loess deposits on the eastern Tibetan Plateau are derived from heterogeneous local sources.

  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. 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

  14. 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.

  15. Sedimentary-hosted polymetallic massive sulfide deposits of the Kebrit and Shaban Deeps, Red Sea

    NASA Astrophysics Data System (ADS)

    Blum, N.; Puchelt, H.

    1991-07-01

    Massive sulfides recovered from the Kebrit Deep carbonaceous sedimentary succession represent black smoker fragments, novel to any Red Sea brine pool deposit. Chimneys, which were also observed in situ near the seawater/brine interface of the Kebrit Deep pool, are primarily comprised of Fe-, Zn- and Pb-bearing phases, and are often tar and asphalt impregnated. Cu-sulfides are virtually absent from parageneses, contrasting rift-related smoker and Red Sea metalliferous sediment deposits. Concentration of nickel in discrete bravoite points to a basalt/seawater leaching process as a source for most metals. The sedimentary package, which probably hosts Cu-mineralization in lower stockworks of the smoker deposit, is considered the major source of lead. Prevention of boiling of hydrothermal fluids, passing through a succession of organic-rich carbonate and clay horizons prior to discharge, is essential for smoker formation. Shaban Deep sedimentary-hosted massive sulfides are less frequent, with pyrite being the dominant ore mineral. Sulfur isotope data indicate both high temperature inorganic as well as biogenic sulfate (seawater and/or evaporite) reduction in sulfide-forming processes. Cogenetic sulfates formed from residual, bacteriogenically reduced seawater sulfate. Rather low sulfide/sulfate precipitation temperatures of 110 130 °C for the Kebrit brine pool and 100 °C for Shaban Deep massive sulfides are evident.

  16. Neogene sedimentary evolution of Baja California in relation to regional tectonics

    NASA Astrophysics Data System (ADS)

    Helenes, J.; Carreño, A. L.

    1999-11-01

    During the Neogene, the tectonic and sedimentary evolution of the Baja California Peninsula followed four stages: (1) during the early Miocene (22 Ma), the initiation of transform motion between Pacific and North American plates, caused a rapid subsidence in the Continental Borderland Province and in some adjacent areas.This subsidence coincided in time with with a global rise in sea level. At this time, the eastern and southern parts of the peninsula did not show any evidence of subsidence. (2) During the middle Miocene (12 Ma), normal and strike slip faulting migrated eastward, causing subsidence in the northern part of the Gulf of California, where the oldest Tertiary marine sedimentary rocks were deposited. The areas in central Baja California Sur and the central part of the Gulf itself received abundant volcanic deposits related to continental extension. (3) During the late Miocene (8 Ma), the western margin of the Peninsula changed to a slightly compressive regime, while the northern part of the Gulf contained a marine basin with upper bathyal environments. The central area of the Gulf continued receiving abundant volcanic deposits, while the Los Cabos block received marine sedimentation, correlatable with sedimentary units reported from the continental margins in Nayarit, Jalisco and Michoacán. (4) Beginning in the early Pliocene (5 Ma), the present configuration of the Gulf of California developed through right-lateral strike slip and extension in the Gulf itself. Since Pliocene times, the Gulf presents widespread marine sedimentation with deep basins reaching lower bathyal depths.

  17. 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.

  18. Natural product biomarkers as indicators of sources and transport of sedimentary organic matter in a subtropical river.

    PubMed

    Jaffé, Rudolf; Rushdi, Ahmed I; Medeiros, Patricia M; Simoneit, Bernd R T

    2006-09-01

    The sources and transformations of sedimentary organic matter along the Harney River, a representative subtropical river of the Florida Everglades, were assessed using a natural product biomarker approach. Sediment samples were collected from the headwaters to the Continental Shelf, with characteristic vegetation dominated by freshwater marsh species, mangrove (middle to lower estuary), and seagrass as the marine end-member. A peat sample was collected inland. All sample extracts were analyzed by GC-MS as underivatized and as silylated compounds. With these total extract analyses, major compound classes can be defined: n-alkanols, n-alkanoic acids, methyl alkanoates, methyl alpha- and omega-hydroxyalkanoates, triterpenoids, phytosterols and saccharides, with traces of hydrocarbons. In general, the peat sample extract has a different overall composition compared to the sediment extracts. The major differences include distinct carbon number maxima for the lipid series (e.g., C(max)=28 for n-alkanols) probably from sawgrass and periphyton biomass, and predominance of phytosterols (sitosterol and stigmasterol) from higher plant detritus. In contrast, river sediment extracts contain biomarkers predominantly from mangrove-derived organic matter, such as the triterpenoids taraxerol and myricadiol. Significant amounts of saccharides and omega-hydroxyalkanoates are also found. Generally, compound concentrations decrease downstream due to dilution, and alteration of organic compounds from plant waxes and coastal vegetation is obvious in both peat and sediment samples. This is confirmed by the significant low abundance of n-alkanes and n-alkenoic acids due to biodegradation, oxidation of alpha-tocopherol to homophytanic acid gamma-lactone, and presence of traces of dihydrolacunosic acid, a photochemical alteration product of taraxerol.

  19. 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…

  20. 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 researchers. The study…

  1. 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.

  2. 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…

  3. Classroom Issues with Series Tests

    ERIC Educational Resources Information Center

    Sadek, Jawad; Euler, Russell

    2005-01-01

    We find infinite series in calculus to be one of the most confusing topics our students encounter. In this note, we look at some issues that our students find difficult or ambiguous involving the Ratio Test, the Root Test, and also the Alternating Series Test. We offer some suggestions and some examples, which could be a supplement to the set of…

  4. Are Eddy Covariance series stationary?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Spectral analysis via a discrete Fourier transform is used often to examine eddy covariance series for cycles (eddies) of interest. Generally the analysis is performed on hourly or half-hourly data sets collected at 10 or 20 Hz. Each original series is often assumed to be stationary. Also automated ...

  5. 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…

  6. 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

  7. 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

  8. Tectonostratigraphic reconstruction Cretaceous volcano-sedimentary in the northwestern Andes: from extensional tectonics to arc accretion.

    NASA Astrophysics Data System (ADS)

    Zapata, S.; Patino, A. M.; Cardona, A.; Mejia, D.; Leon, S.; Jaramillo, J. S.; Valencia, V.; Parra, M.; Hincapie, S.

    2014-12-01

    Active continental margins characterized by continuous convergence experienced overimposed tectonic configurations that allowed the formation of volcanic arcs, back arc basins, transtensional divergent tectonics or the accretion of exotic volcanic terranes. Such record, particularly the extensional phases, can be partially destroyed and obscure by multiple deformational events, the accretion of exotic terranes and strike slip fragmentation along the margin. The tectonic evolution of the northern Andes during the Mesozoic is the result of post Pangea extension followed by the installation of a long-lived Jurassic volcanic arc (209 - 136 ma) that apparently stops between 136 Ma and 110 Ma. The Quebradagrande Complex has been define as a single Lower Cretaceous volcano-sedimentary unit exposed in the western flank of the Central Cordillera of the Colombian Andes that growth after the Late Jurassic to Early Cretaceous magmatic hiatus. The origin of this unit have been related either to an oceanic volcanic arc or a marginal basin environment. The existence of such contrasting models reflect the regional perspective followed in published studies and the paucity of detail analysis of the volcano-sedimentary sequences.We integrate multiple approaches including structural mapping, stratigraphy, geochemistry, U-Pb provenance and geochronology to improve the understanding of this unit and track the earlier phases of accumulation that are mask on the overimposed tectonic history. Our preliminary results suggest the existence of different volcano-sedimentary units that accumulated between 100 Ma and 82 Ma.The older Lower Cretaceous sequences was deposited over Triassic metamorphic continental crust and include a upward basin deepening record characterized by thick fan delta conglomerates, followed by distal turbidites and a syn-sedimentary volcanic record at 100 ma. The other sequence include a 85 - 82 Ma fringing arc that was also formed close to the continental margin or

  9. 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

  10. Characterizing the Biological and Geochemical Architecture of Hydrothermally Derived Sedimentary Deposits: Coupling Micro Raman Spectroscopy with Noble Gas Spectrometry

    NASA Astrophysics Data System (ADS)

    Bower, D. M.; Conrad, P. G.; Steele, A.; Fries, M. D.

    2016-05-01

    The chemical species in cherts and glass fragments were analyzed using micro Raman spectroscopy in conjunction with measurements of heavy noble gas isotopes to characterize hydrothermally derived sedimentary environments.

  11. 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)

  12. 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

  13. 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

  14. A study of uranium favorability of Cenozoic sedimentary rocks, Basin and Range Province, Arizona: Part I, General geology and chronology of pre-late Miocene Cenozoic sedimentary rocks

    USGS Publications Warehouse

    Scarborough, Robert Bryan; Wilt, Jan Carol

    1979-01-01

    This study focuses attention on Cenozoic sedimentary rocks in the Basin and Range Province of Arizona. The known occurrences of uranium and anomalous radioactivity in these rocks are associated with sediments that accumulated in a low energy environment characterized by fine-grained clastics, including important tuffaceous materials, and carbonate rocks. Most uranium occurrences, in these rocks appear to be stratabound. Emphasis was placed on those sedimentary materials that pre-date the late Cenozoic Basin and Range disturbance. They are deformed and crop out on pedimented range blocks and along the province interface with the Transition Zone. Three tentative age groups are recognized: Group I - Oligocene, pre-22 m.y., Group II - early Miocene - 22 m.y. - 16 m.y., and Group III - middle Miocene - 16 m.y. to 13--10 m.y. Regionally, these three groups contain both coarse to fine-grained red clastics and low energy lighter colored 'lacustrine' phases. Each of the three groups has been the object of uranium exploration. Group II, the early Miocene strata, embraces the Anderson Mine - Artillery region host rocks and also the New River - Cave Creek early Miocene beds-along the boundary with the Transition Zone. These three groups of rocks have been tectonically deformed to the extent that original basins of deposition cannot yet be reconstructed. However, they were considerably more extensive in size than the late Cenozoic basins the origin of which deformed the former. Group II rocks are judged to be of prime interest because of: (1) the development and preservation of organic matter in varying lithologies, (2) apparent contemporaneity with silicic volcanic centers, (3) influence of Precambrian crystalline rocks, and (4) relative outcrop continuity near the stable Transition Zone. The Transition Zone, especially along its boundary with the Basin and Range Province, needs additional geologic investigation, especially as regards the depositional continuity of Group II

  15. 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

  16. Mature area of new frontier Northeast British Columbia reveals new high potential in the structurally complex region of the western Canada sedimentary basin

    SciTech Connect

    Hutton, A.N.; Varsek, J.L. )

    1993-09-01

    Northeast British Columbia has been extensively explored since the early fifties. Evaluated as a part of the Western Canada sedimentary basin, with a passive undeformed basement and only Laramide deformation, the basin must be considered mature. Recent work involving detailed stratigraphic analysis, extensive field observations, potential field data analysis, and deep crustal reflection seismic work lead to an exciting new view of this portion of the Western Canada basin. Situated over the middle Proterozoic continental margin, a complexly deformed and deeply truncated foreland forms a ramp against highly magnetic crystalline rocks. Dipping features within the Proterozoic intersect the Phanerozoic, producing local structure and uplift which has had a profound influence on Devonian reef paleogeography. A major contractional episode created previously unrecognized Devonian to Carboniferous folds and this discovery has led to a complete reinterpretation of the structural style and deformational history of the area. The structural complexity of the basin is increased by right lateral strike-slip faulting. This system is highlighted in the subsurface by a series of faults fanning out across the basin with displacements of up to 20 km in the Proterozoic foreland and accommodation continuing until the Cretaceous. Strike-slip deformation has generated an embayment in the Proterozoic continental margin and within the Phanerozoic shelf, indicating the occurrence of several previously unrecognized prospective shelf to basin transitions. The complex interplay of structure and paleogeography results in a series of play opportunities that could result in new giant discoveries.

  17. 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. PMID:27494189

  18. Sedimentary development and correlation of Late Quaternary terraces in the Kyrenia Range, northern Cyprus, using a combination of sedimentology and optical luminescence data

    NASA Astrophysics Data System (ADS)

    Palamakumbura, Romesh N.; Robertson, Alastair H. F.; Kinnaird, Tim C.; Sanderson, David C. W.

    2016-01-01

    This study focuses on the younger of a series of Quaternary terraces along the flanks of the Kyrenia Range in northern Cyprus, specifically the Kyrenia (Girne) and the Koupia terraces. The Kyrenia (Girne) terrace is tentatively correlated with oxygen isotope stage 5 (125 Ka), and the Koupia terrace with oxygen isotope stage 3 (<50 Ka). Along the northern flank of the range, the Kyrenia (Girne) terrace deposits (5-20 m above modern sea level) typically begin with a basal lag conglomerate and then pass upwards into shallow-marine calcarenites and then into variable aeolianites, paleosols and fluvial deposits (up to 20 m thick). In contrast, the Koupia terrace (<2 m above modern sea level) consists of aeolianites and shallow-marine calcarenites (up to 8 m thick). The equivalent deposits along the southern flank of the range are entirely non-marine fluvial mud, sands and conglomerates. The marine to continental terrace systems can be tentatively correlated based on mapping, height above modern sea level and sedimentary facies. However, variable preservation and patchy exposure require such correlations to be independently tested. To achieve this, a portable optically stimulated luminescence (OSL) reader was used to determine the luminescence characteristics of the two terrace systems. Luminescence profiles show major differences in luminescence characteristics between the two terrace depositional systems, which can be related to sedimentary processes, provenance and age. These features allow sections in different areas to be effectively correlated. Individual sections show luminescence properties that are generally consistent with an expected up-sequence decrease in age. However, the younger Koupia terrace deposits show higher luminescence intensities compared with the older Kyrenia (Girne) terrace deposits. This can be explained by multiple phases of reworking of the Kyrenia (Girne) terrace deposits, which changed the luminescence characteristics of the sediment. The

  19. Austrian phase on the northern African margin inferred from sequence stratigraphy and sedimentary records in southern Tunisia (Chotts and Djeffara areas)

    NASA Astrophysics Data System (ADS)

    Lazzez, Marzouk; Zouaghi, Taher; Ben Youssef, Mohamed

    2008-08-01

    A multidisciplinary study concerning Aptian and Albian deposits is reported from petroleum wells and the exposed section. The biostratigraphic and sedimentological analysis defined four sedimentary units. Well-logging signals' analysis allows us to refine the record resolution on Aptian series and reveals, in the Djeffara field, a transgressive system tract (TST) and a highstand system tract (HST). Exceptionally, the first sequence (S1) in the Mareth 1 well and the fifth sequence in the two wells Mareth 1 and Gourine 1 reveal the lower-stand system tract (LST). The unconformities characterized by the absence of Upper Aptian (Clansayesian) and Lower to Middle Albian deposits signed by a significant gamma-ray reduction. The Middle and Upper Albian is represented by only one deposit sequence (S6) in Mareth 1. Towards the south, in the Gourine well, two deposit sequences were identified (S6 and S7); to specify the Aptian and Albian evolution of the deposit sequences, a tentative correlation has been established between the Chotts and Djeffara areas. This correlation allows us to characterize the sedimentary unconformities related to the tectonics and eustatic events. The Chotts and the Djeffara deposition areas were developed, characterized by an irregular subsidence and separated by the Tebaga Medenine high area. The Aptian-Albian subsidence platform of southern Tunisia may be considered as a block diagram of environmental deposit with regressive and transgressive trends, showing the impact of tectonic deformations on the palaeogeographic evolution of southeastern Tunisia during the Austrian phase. This study also must be replaced within regional structural patterns that may explain both the sequential and sedimentological evolution of the area. Deformations regionally identified are integrated in the more general context of both Tethyan and Atlantic areas related to the drift of the African platform.

  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. Cyclicity in Pleistocene upper-slope cool-water carbonates: Unravelling sedimentary dynamics in deep-water sediments, Great Australian Bight, Odp Leg 182, Site 1131A

    NASA Astrophysics Data System (ADS)

    Puga-Bernabéu, Ángel; Betzler, Christian

    2008-03-01

    Ocean Drilling Program Site 1131, located in the central Great Australian Bight, recovered an expanded series of Pleistocene cool-water carbonates. Three distinct facies are arranged in repeating sedimentary cycles. Omission intervals form the base of the cycles and are overlain by laminated deposits. The upper part of the cycles consists of bioturbated sediments. Facies cyclicity parallels glacial-interglacial sea-level changes. Firmground/hardground surfaces formed during latest stages of sea-level falls. Laminated sediments were deposited during later sea-level fall and/or early phases of the sea-level lowstand, and the bioturbated intervals are related to interglacial sea-level highstands. Bottom current activity is interpreted to play an important control on facies and cycle development. During the late stages of sea-level fall, upwelling currents winnowed the slope sediments, leading to hardground formation. During latest sea-level falls and early sea-level lowstands, a relative increase in the ramp sediment supply to the slope leading to the formation of the laminated facies was also a response to the continued action of the near-bottom upwelling currents that reworked previously deposited sediments along the slope. During the early sea-level rises, laminated, upwelling-influenced facies were progressively covered by the bioturbated facies. The adopted approach to decipher sedimentary cyclicity, involving the integrated use of wireline logs, geochemical data, FMS images and sedimentological analysis of the lithofacies has allowed to recognise subtle facies changes in upper-slope settings of a distally-steepened carbonate ramp and their relationship with the sea level, as well as to unravel the importance of the oceanic-current regime in the deposition style on the ramp that otherwise would remain unsolved. This integrated method could be applied to study more precisely apparently homogeneous fine-grained calcareous sediment successions of distal

  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. "Feeling" Series and Parallel Resistances.

    ERIC Educational Resources Information Center

    Morse, Robert A.

    1993-01-01

    Equipped with drinking straws and stirring straws, a teacher can help students understand how resistances in electric circuits combine in series and in parallel. Follow-up suggestions are provided. (ZWH)

  4. Castle series, 1954. Technical report

    SciTech Connect

    Martin, E.J.; Rowland, R.H.

    1982-04-01

    CASTLE was an atmospheric nuclear weapons test series held in the Marshall Islands at Enewetak and Bikini atolls in 1954. This is a report of DOD peronnel in CASTLE with an emphasis on operations and radiological safety.

  5. Clustering of financial time series

    NASA Astrophysics Data System (ADS)

    D'Urso, Pierpaolo; Cappelli, Carmela; Di Lallo, Dario; Massari, Riccardo

    2013-05-01

    This paper addresses the topic of classifying financial time series in a fuzzy framework proposing two fuzzy clustering models both based on GARCH models. In general clustering of financial time series, due to their peculiar features, needs the definition of suitable distance measures. At this aim, the first fuzzy clustering model exploits the autoregressive representation of GARCH models and employs, in the framework of a partitioning around medoids algorithm, the classical autoregressive metric. The second fuzzy clustering model, also based on partitioning around medoids algorithm, uses the Caiado distance, a Mahalanobis-like distance, based on estimated GARCH parameters and covariances that takes into account the information about the volatility structure of time series. In order to illustrate the merits of the proposed fuzzy approaches an application to the problem of classifying 29 time series of Euro exchange rates against international currencies is presented and discussed, also comparing the fuzzy models with their crisp version.

  6. 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

  7. Carbon remineralization in the Amazon Guianas tropical mobile mudbelt: A sedimentary incinerator

    NASA Astrophysics Data System (ADS)

    Aller, Robert C.; Blair, Neal E.

    2006-11-01

    The Amazon River spawns a vast mobile mudbelt extending ˜1600 km from the equator to the Orinoco delta. Deposits along the Amazon-Guianas coastline are characterized by some of the highest C org remineralization rates reported for estuarine, deltaic, or shelf deposits, however, paradoxically, except where stabilized by mangroves or intertidal algal mats, they are usually suboxic and nonsulfidic. A combination of tides, wind-driven waves, and coastal currents forms massive fluid muds and mobile surface sediment layers ˜0.5-2 m thick which are dynamically refluxed and frequently reoxidized. Overall, the seabed functions as a periodically mixed batch reactor, efficiently remineralizing organic matter in a gigantic sedimentary incinerator of global importance. Amazon River material entering the head of this dynamic dispersal system carries an initial terrestrial sedimentary C org loading of ˜ 0.7 mg C m -2 particle surface area. Total C org loading is lowered to ˜ 0.2 mg C m -2 in the proximal delta topset, ˜60-70% of which remains of terrestrial origin. Loading decreases further to 0.12-0.14 mg C m -2 (˜60% terrestrial) in mudbanks ˜600 km downdrift along French Guiana, values comparable to those found in the oligotrophic deepsea. DOC/ΣCO 2 ratios in pore waters of French Guiana mudbanks indicate that >90% of metabolized organic substrates are completely oxidized. Within the Amazon delta topset at the head of the dispersal system, both terrestrial and marine organic matter contribute substantially to early diagenetic remineralization, although reactive marine substrate dominates (˜60-70%). The conditional rate constant for terrestrial C org in the delta topset is ˜0.2 a -1. As sedimentary C org is depleted during transit, marine sources become virtually the exclusive substrate for remineralization except very near the mangrove shoreline. The δ13C and Δ 14C values of pore water ΣCO 2 in mudbanks demonstrate that the primary source of remineralized organic

  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. 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

  10. Ganged series potentiometer mixer networks

    NASA Technical Reports Server (NTRS)

    Burhans, R. W.

    1974-01-01

    A ganged potentiometer with the interesting property of a constant 10k ohm or greater series impedance for all rotations of the shaft was rediscovered. The device provided a versatile passive mixer circuit when used with most signal sources and can be used as a variable series input summing resistor in operational amplifier networks. The potentiometer gave simple solutions to missing problems with a single control knob.

  11. 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.

  12. 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

  13. 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.

  14. Evidence for the preservation of technogenic tritiated organic compounds in an estuarine sedimentary environment.

    PubMed

    Croudace, Ian W; Warwick, Phillip E; Morris, Jenny E

    2012-06-01

    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.

  15. Adjoint-tomography Inversion of the Small-scale Surface Sedimentary Structures: Key Methodological Aspects

    NASA Astrophysics Data System (ADS)

    Kubina, Filip; Moczo, Peter; Kristek, Jozef; Michlik, Filip

    2016-04-01

    Adjoint tomography has proven an irreplaceable useful tool in exploring Earth's structure in the regional and global scales. It has not been widely applied for improving models of local surface sedimentary structures (LSSS) in numerical predictions of earthquake ground motion (EGM). Anomalous earthquake motions and corresponding damage in earthquakes are often due to site effects in local surface sedimentary basins. Because majority of world population is located atop surface sedimentary basins, it is important to predict EGM at these sites during future earthquakes. A major lesson learned from dedicated international tests focused on numerical prediction of EGM in LSSS is that it is hard to reach better agreement between data and synthetics without an improved structural model. If earthquake records are available for sites atop a LSSS it is natural to consider them for improving the structural model. Computationally efficient adjoint tomography might be a proper tool. A seismic wavefield in LSSS is relatively very complex due to diffractions, conversions, interference and often also resonant phenomena. In shallow basins, the first arrivals are not suitable for inversion due to almost vertical incidence and thus insufficient vertical resolution. Later wavefield consists mostly of local surface waves often without separated wave groups. Consequently, computed kernels are complicated and not suitable for inversion without pre-processing. The spatial complexity of a kernel can be dramatic in a typical situation with relatively low number of sources (local earthquakes) and surface receivers. This complexity can be simplified by directionally-dependent smoothing and spatially-dependent normalization that condition reasonable convergence. A multiscale approach seems necessary given the usual difference between the available and true models. Interestingly, only a successive inversion of μ and λ elastic moduli, and different scale sequences lead to good results.

  16. 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.

  17. Geological Consequences of Unequal Loading of Sedimentary Units, at Passive, Transform, and Convergent Margins

    NASA Astrophysics Data System (ADS)

    Moore, C.; Dugan, B.; Flemings, P.; Iturrino, G.; Sawyer, D.; Behrmann, J.; John, C.

    2005-12-01

    An investigation of the effects of unequal loading of permeable sedimentary units and potential lateral flow was a primary objective of IODP Exp. 308 in the Gulf of Mexico. In addition to occurrence at passive margins, the geological consequences of unequal loading of aquifers is prominent at transform and at convergent margins. The development of a pull-apart basin along the San Andreas Transform Fault system resulted in a large difference in sedimentary loading in the upper Miocene Santa Margarita Sandstone near Santa Cruz CA. The overlying diatomaceous mudstone shows a variation in thickness from about 3 km at the basin center to several hundred meters at the basin margin. At the basin margin the underlying sandstone injects the overlying mudstone as dikes and sills and also flowed onto the Miocene seafloor as a sand volcano. In the Late Cretaceous-Paleocene Great Valley Forearc Basin Sequence, similar sandstone dikes and sills occur at the basin margin where the overlying sedimentary cover is minimized. However the lateral variation in thickness of the overlying mudstone sequence (1100m to ~ 800 m) is less dramatic than in the San Andreas Fault system example. The abundance of sills in both the Great Valley and San Andreas Fault system examples unequivocally indicate that the fluid pressures reached lithostatic values. In both examples, hydrocarbons reduced the density of fluids and assisted in reaching fluid pressures equal to the overburden. In the Ursa Basin Exp. 308 measured fluid pressures of ~ 0.6 of effective vertical stress in the muds overlying the unequally loaded permeable sandy "Blue Unit". Drilling and preliminary investigation of the seismic and borehole imaging data indicate no evidence of dikes or sills emanating from the Blue Unit. Therefore, the fluid pressure conditions in the Blue Unit and the overlying muds apparently define a lower limit for the formation of clastic intrusions.

  18. 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.

  19. Evidence for the preservation of technogenic tritiated organic compounds in an estuarine sedimentary environment.

    PubMed

    Croudace, Ian W; Warwick, Phillip E; Morris, Jenny E

    2012-06-01

    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. PMID:22559077

  20. Historical eutrophication in the Changjiang and Mississippi delta-front estuaries: Stable sedimentary chloropigments as biomarkers

    NASA Astrophysics Data System (ADS)

    Zhao, Jun; Bianchi, Thomas S.; Li, Xinxin; Allison, Mead A.; Yao, Peng; Yu, Zhigang

    2012-09-01

    Eutrophication is one of the most significant ecological problems in large-river delta-front estuaries (LDEs) around the world. We used TOC, TN, δ13C, δ15N and three stable sedimentary chloropigments (pyropheophytin-a [pPHtin-a], sterol chlorin esters [SCEs] and carotenol chlorin esters [CCEs]) as geochemical proxies to examine historical trends of eutrophication over the last few decades in the Changjiang and Mississippi LDEs. Concentrations of sedimentary pPHtin-a, SCEs and CCEs increased from 15, 12 and 120 nmol g-1 OC in 1960s to 51, 32 and 256 nmol g-1 OC in 1990s on the inner shelf of the East China Sea, respectively, and from 57, 69 and 31 nmol g-1 OC in 1950s to 70, 90 and 44 nmol g-1 OC in 2000s in the Mississippi Canyon, respectively. Riverine loading of DIN flux to LDE increased from (261±109)×106 kg yr-1 in pre-1980 to (1385±209)×106 kg yr-1 in post-1990 in the Changjiang LDE, while nitrate flux increased from (322±89)×106 kg yr-1 in the 1950s to 1960s to (589±123)×106 kg yr-1 in the 1970s, and DIN flux kept relatively stable in (963±250)×106 kg yr-1 from the 1980s to 2000s in the Mississippi LDE. This work reveals that the stable sedimentary chloropigments in accumulating sediments on the inner shelf are suitable biomarkers for examining past changes in eutrophication in the Changjiang and Mississippi LDE ecosystems. The historical record of riverine nutrient inputs as related to changes in the watershed (e.g., fertilizers and manure) is well-correlated with down-core concentrations of stable pheopigment biomarkers in sediments at both LDEs. These results support the coupling between enhanced phytoplankton abundance and increasing anthropogenic nutrients input to the inner shelves of these LDEs.

  1. An object-oriented expert system for sedimentary basin analysis with applications in petroleum geology

    SciTech Connect

    Miller, B.M. )

    1990-05-01

    Most of the world's energy resources and many of its metallic and mineral resources are derived from complex sources in sedimentary basins. A comprehensive basin analysis requires an understanding of data from many specialties, including sedimentology, stratigraphy geophysics, structural geology, and geochemistry. Such an integrated analysis is almost impossible without a computer. Research efforts in the US Geological Survey are currently being directed at exploring the feasibility of applying expert systems and knowledge acquisition techniques to the design and development of a global system of classification and geological analysis of sedimentary basins to assess their petroleum potential. The primary objective is the design of a prototype object-oriented expert system interfaced with a geographic information system (GIS) that captures both the logic used to define the geologic concepts and the reasoning under uncertainty that enables geologists to understand and reconstruct the geologic history of a sedimentary basin. NEXPERT OBJECT, a hybrid expert system that has the ability to support both a reasoning system and an object-oriented representation, is currently being used as the design tool to provide high-level, expert-oriented features to create, edit, and build knowledge bases for the basin analysis program. This system provides these capabilities through documentation of major basin analysis components such as stratigraphy, structural geology, and sedimentology. It is designed to analyze the traditional concepts of source, reservoir, and trapping mechanism; to help in the diagnosis of geological conditions favorable for the occurrence of petroleum or other energy resources; and to assist in the assessment of these resources. The design and content of the expert system program is discussed for application to basin analysis studies.

  2. 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

  3. 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

  4. Is Planktonic Diversity Well Recorded in Sedimentary DNA? Toward the Reconstruction of Past Protistan Diversity.

    PubMed

    Capo, Eric; Debroas, Didier; Arnaud, Fabien; Domaizon, Isabelle

    2015-11-01

    Studies based on the coupling of a paleolimnological approach and molecular tools (e.g., sequencing of sedimentary DNA) present a promising opportunity to obtain long-term data on past lacustrine biodiversity. However, certain validations are still required, such as the evaluation of DNA preservation in sediments for various planktonic taxa that do not leave any morphological diagnostic features. In this study, we focused on the diversity of planktonic unicellular eukaryotes and verified the presence of their DNA in sediment archives. We compared the molecular inventories (high-throughput sequencing of 18S ribosomal DNA) obtained from monitoring the water column with those obtained for DNA archived in the first 30 cm of sediment. Seventy-one percent of taxonomic units found in the water samples were detected in sediment samples, including pigmented taxa, such as Chlorophyta, Dinophyceae, and Chrysophyceae, phagotrophic taxa, such as Ciliophora, parasitic taxa, such as Apicomplexa and Chytridiomycota, and saprotrophs, such as Cryptomycota. Parallel analysis of 18S ribosomal RNA (rRNA) transcripts revealed the presence of living eukaryotic taxa only in the top 2 cm of sediment; although some limits exist in using RNA/DNA ratio as indicator of microbial activity, these results suggested that the sedimentary DNA mostly represented DNA from past and inactive communities. Only the diversity of a few groups, such as Cryptophyta and Haptophyta, seemed to be poorly preserved in sediments. Our overall results showed that the application of sequencing techniques to sedimentary DNA could be used to reconstruct past diversity for numerous planktonic eukaryotic groups.

  5. Modelling depositional shifts between sedimentary basins: Sediment pathways in Paratethys basins during the Messinian Salinity Crisis

    NASA Astrophysics Data System (ADS)

    Bartol, J.; Matenco, L.; Garcia-Castellanos, D.; Leever, K.

    2012-04-01

    The evolution of sedimentary basins separated by uplifted topographic barriers is characterised by gradual regressive deposition until one of the basins is filled and its sedimentation bypasses to the adjacent basin, defining a depositional shift. One of the critical parameters controlling these depositional shifts is sea level variation, its drop potentially triggering a depositional shift by cancelling the available accommodation space. Conversely, a sea level rise can create new accommodation space resulting in a depositional shift towards a previously overfilled basin. Here we use a three dimensional numerical model to study the sedimentary response to sea level variations of a system of two basins. In this model, a single mountainous source area is feeding an intra-continental basin that is separated by a submarine barrier from another basin with normal marine bathymetry. The sedimentary response is modelled during a cycle of sea-level drop and subsequent rebound that exposes the barrier to sub-aerial erosion. The examined parameters are the barrier height, magnitude and duration of sea level change, climate and flexural rigidity. Modelling demonstrates that shifting the bulk of sedimentation from the continental basin to the open marine environment requires some minimum magnitudes and durations of sea level drop. Moreover, given the specific geometry and parameters of our model, an intervening barrier causes a delay of up to 0.35 Myr, depending on the magnitude and duration of sea level change, to the onset of an outward depositional shift when compared to a situation without a barrier. These depositional shifts depend on changes in climate, magnitude and duration of sea level change. Model results are applied to the connectivity between the Black Sea and the Dacic Basin, suggesting that depositional shifts observed during the Messinian Salinity Crisis can be explained by a sea level drop of > 1000 m in the Black Sea.

  6. [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.

  7. 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.

  8. 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.

  9. Linking margin morphology to sedimentary processes along the US East Coast passive continental margin

    NASA Astrophysics Data System (ADS)

    Brothers, D. S.; ten Brink, U. S.; Andrews, B.; Twichell, D.

    2010-12-01

    The morphology of the US East Coast continental slope and rise has a surprising amount of along-margin variation. Multibeam bathymetry datasets that cover the slope and rise from Cape Hatteras to Georges Bank provide a unique opportunity to analyze both first-order and higher-order morphologies, including submarine canyons, landslides, slumps and sedimentary bedforms. Using the morphological characterization coupled with seismic and core data, we hope to better understand how ancient and modern sedimentary processes control the shape of the margin. As a first step, the margin bathymetry was subdivided into 20 shelf-perpendicular regions from which several statistical parameters were analyzed. Within each region, the slope gradient was computed separately for down-slope and across-slope aspect directions. Distribution curves in each region for down- and across-slope gradients and seafloor roughness as functions of depth were grouped according to their statistical similarities. Four basic groups emerge and each approximately corresponds to known regions of Quaternary glacial, fluvial, current-controlled and gravity-driven sedimentary transport. In the second part of the study, published lithologic and chronostratigraphic frameworks of this margin were used to examine the relationship between seafloor morphology and the underlying geology. Along the upper continental rise, thick Quaternary deposits appear to have a strong influence on the short- and long-wavelength variation in rise topography, revealing a complex interplay between down-slope and along-slope sediment transport. Despite the close correlation between continental slope morphology and Quaternary environmental conditions, initial results suggest that the underlying, older, stratigraphy also plays a primary role. Along the continental slope, Quaternary processes appear to control the relief of slope-confined canyons and other short-wavelength (<5 km) topography, but the first order morphology of the slope

  10. High resolution temperature models for geothermal exploration in sedimentary basins: methods and applications

    NASA Astrophysics Data System (ADS)

    van Wees, Jan-Diederik; Bonte, Damien; Verweij, Hanneke; Kramers, Leslie

    2010-05-01

    Key to geothermal exploration success is sufficiently high temperature. This paper focusses on high resolution temperature prediction for geothermal exploration in sedimentary basins. In existing thermal basin models for oil and gas exploration, the focus is on predicting past temperature histories in the sedimentary cover for assessment of oil and gas maturation and expulsion. For detailed 3D models (i.e. involving millions of temperature nodes) these models take long to run and are hard to calibrate to both temperature data in wells and lithosphere boundary conditions. Moreover, spatial variations in basal heat flow is generally not controlled by tectonic boundary conditions. Tectonic models, capable of modelling the thermal consequences of basin evolution, allow to asses spatial heat flow variability based on lithosphere deformation, and provide additional constraints and better quantitative understanding of temperature anomalies. In order to improve modeling capability in terms of model resolution and incorporating tectonic effects, we have developed a novel 3D thermal basin model. In the model transient temperatures are calculated over the last 20 Million years for a 3D heat equation on a regular 3D finite difference grid, allowing for spatial variation in thermal properties, temporal variation in surface temperature and spatial and temporal variations in basal heat flow. Furthermore the model takes into account heat advection, including effects of sedimentation, and lithosphere deformation. The model is iteratively calibrated to temperature data at the well locations, typically taking less than 5 runs. In addition well locations basal heat flow conditions are interpolated based on tectonic constraints. The capabilities of the model are demonstrated for various sedimentary basins, including the Netherlands. The models have been calibrated to extensive well data, showing considerable spatial variability which appears to be related to both tectonic variation as

  11. 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

  12. Geochemical background values for trace elements in arable soils developed from sedimentary rocks of glacial origin.

    PubMed

    Czarnowska, K; Gworek, B

    1990-12-01

    The total content of trace elements was examined in some arable soils developed from boulder loam and silt formations of the Middle Poland and Baltic glaciations (62 profiles). Mean element concentrations calculated on the basis of chemical and statistical analyses were as follows: Mn = 322; Zn = 36; Cr = 30; Ni = 12.7; Pb = 10.3; Cu = 8.8; Co = 4.7; and Cd = 0.27 in mg kg(-1) of soil dry weight. The authors propose to accept these figures as the geochemical background values for soils derived from sedimentary rocks of glacial origin.

  13. Petrology and mineral chemistry of sedimentary rocks from the Western Solomon Sea

    NASA Astrophysics Data System (ADS)

    Crook, Keith A. W.

    1986-12-01

    Sedimentary rocks from the northern margin of the Trobriand Platform, the north wall of the New Britain Trench, and the floor of the Solomon Sea Basin are volcaniclastics, mudrocks, and neritic and bathyal limestones. Arc-volcanic debris from calc-alkaline or high-K magmatic sources is present at each locality. A minor metamorphic component occurs at one site on the Trobriand Platform which yielded Early Eocene to Middle Miocene material, and at the New Britain Trench site, which yielded Miocene or older and post-Miocene samples. Solomon Sea Basin samples are mudrocks which are apparently no older than Late Pliocene.

  14. Sedimentary pigments on the Pakistan margin: Controlling factors and organic matter dynamics

    NASA Astrophysics Data System (ADS)

    Woulds, Clare; Cowie, Greg L.

    2009-03-01

    Sedimentary pigments can provide information on various aspects of benthic processes and biogeochemistry. In this study, sediments from sites at depths of 140 to 1850 m spanning the Pakistan margin oxygen minimum zone (OMZ), and representing dramatic contrasts in depositional conditions and benthic communities, were analysed for pigment yields and compositions. This has allowed a rare consideration of how different factors, including oxygen concentration, organic matter (OM) supply and biological activity (e.g., degree of bioturbation) may influence sedimentary pigment distribution in a continental margin environment. It has also allowed one of the first efforts to study the impact of biological activity on pigment concentrations in the natural environment, rather than in a microcosm setting. Total extractable surface sediment pigment concentrations showed a range of ˜1.5-49 μg g -1 of dry sediment. The pigment suite was dominated by pheophytin and pheophorbide (which together constituted ˜75% of total pigments), with minor amounts of chlorophyll- a, alloxanthin, diatoxanthin, zeaxanthin and β-carotene. Low oxygen concentration appeared to influence pigment abundance by increasing the concentration of refractory pigments ultimately buried. In addition, maximal pigment abundances were associated with minimal amounts of sediment mixing by macrofauna, and at one site macrofaunal digestion may have altered the relative dominance of the different pheopigments. In contrast, the lack of a marked increase in pigment concentrations after the summer monsoon plus the lack of a correlation between pigment concentration and water depth suggest that OM supply plays a relatively small role in controlling sedimentary pigments. Pigment concentrations and suites, together with modelled decay half-lives (˜0.8-15 years), suggest that in general OM on the Pakistan margin, despite the low oxygen concentrations and monsoon-driven productivity, is surprisingly degraded compared to

  15. 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

  16. 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

  17. Perimeter-area power-law relationship of pores in sedimentary rocks and implications for permeability

    SciTech Connect

    Schlueter, E.M.; Zimmerman, R.W.; Cook, N.G.W.; Witherspoon, P.A.

    1994-12-31

    Perimeter-area power-law relationships of pores in five sedimentary rocks are determined from scanning electron photomicrographs of thin sections. These relationships for the pores of four sandstones were found to lie between 1.43 and 1.49, while that of an Indiana limestone was found to be 1.67. The authors discuss how the perimeter-area power-law relationship of pores, along with a pore-size distribution, can be used to estimate the hydraulic permeability.

  18. 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.

  19. Advancing Methods for Hydrogeological Characterization of Deep Aquifers in Sedimentary Basins

    NASA Astrophysics Data System (ADS)

    Singh, A.; Palombi, D.

    2014-12-01

    The Groundwater Program at the Alberta Geological Survey is focused on identifying, characterizing and quantifying Alberta's groundwater resources. Characterization of deep groundwater resources is becoming increasingly important as the Government of Alberta implements its Water Conservation Policy seeking to minimize freshwater use. Conducting an inventory of saline water (non-traditional) resources for source water in various energy development scenarios, at basin scales, pose significant challenges given the potential competing uses and demand for groundwater resources. Current research activities are seeking to improve our methods to characterize deep aquifers in data-rich sedimentary basins. Two methods are discussed here: 1) identifying production/injection influenced Drill Stem Test (DST) measurements for mapping distributions of hydraulic heads (both present-day and prior to development) in deep units; and 2) analyzing variable density flow effects. DSTs are transient pressure tests usually performed for assessing potential oil and gas productivity. These tests measure pressures using gauges at the surface and down-hole. The measured pressures can be strongly influenced in cases where the test interval is located in the vicinity of a production or injection well, which generally happens in mature sedimentary basins such as the Alberta basin. To identify production influences this study utilized a cumulative inference index (CII) based approach. A new application was developed in C-code to implement the CII and will be demonstrated on a sample DST dataset from the Western Canada Sedimentary Basin. Fluid flow in sedimentary basins is often inferred using freshwater hydraulic heads, reference formation water densities and pressure-depth plots. Previous studies in the Alberta basin have often neglected density variations. Effects of density driven flow needs to be taken into account in cases where dense brines are present, a large aquifer dip or small hydraulic

  20. 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.