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OES Faculty Publications

Articles 31 - 39 of 39

Full-Text Articles in Sedimentology

Turbulent Lifestyle: Microbial Mats On Earth’S Sandy Beaches—Today And 3 Billion Years Ago, Nora Noffke Jan 2008

Turbulent Lifestyle: Microbial Mats On Earth’S Sandy Beaches—Today And 3 Billion Years Ago, Nora Noffke

OES Faculty Publications

Archean Earth history is very difficult to reconstruct. Until recently, only bacterial cells preserved in chert, microborings, and stromatolites provided the few clues to ancient life. Now, siliciclastic “microbially induced sedimentary structures” (MISS) are adding to our knowledge of both past life and paleoenvironments. MISS rise from the interaction of photoautotrophic microbial mats with physical sediment dynamics in siliciclastic, shallow-marine settings. Archean MISS can be understood through observations of living microbial mats and modern biotic-physical sedimentary processes. Such geobiological studies are key to the interpretation of the early evolution of prokaryotes. For example, the 2.9 Ga Pongola Supergroup, South Africa, …

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Burial Of Terrestrial Organic Matter In Marine Sediments: A Re-Assessment, David J. Burdige Jan 2005

Burial Of Terrestrial Organic Matter In Marine Sediments: A Re-Assessment, David J. Burdige

OES Faculty Publications

Calculations based on recent observations indicate that approximately one third of the organic matter presently being buried in marine sediments may be of terrestrial origin, with the majority of this terrestrial organic matter (TOM) burial occurring in muddy, deltaic sediments. These calculations further suggest that the remineralization of terrestrial organic matter in the oceans is also much less efficient than that of marine organic matter. These two underappreciated observations have important implications in terms of our understanding of the controls on the global carbon cycle. From a paleoceanographic perspective, the results presented here also suggest that changes in TOM burial …

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Modifications Of The C37 Alkenone And Alkenoate Composition In The Water Column And Sediment: Possible Implications For Sea Surface Temperature Estimates In Paleoceanography, Joan O. Grimalt, Jürgen Rullkötter, Marie-Alexandrine Sicre, Roger Summons, John Farrington, H. Rodger Harvey, Miguel Goñi, Ken Sawada Nov 2000

Modifications Of The C37 Alkenone And Alkenoate Composition In The Water Column And Sediment: Possible Implications For Sea Surface Temperature Estimates In Paleoceanography, Joan O. Grimalt, Jürgen Rullkötter, Marie-Alexandrine Sicre, Roger Summons, John Farrington, H. Rodger Harvey, Miguel Goñi, Ken Sawada

OES Faculty Publications

The literature pertaining to C37 alkenone and C37 and C38 alkenoate production and diagenesis has been reviewed and evaluated for issues that might jeopardize their usefulness in paleotemperature estimation. We also examined the use of the C37 alkenones as paleoproductivity indicators, the stability of their δ13C isotopic compositions, and their incorporation into the nonsolvent extractable organic matter fraction. Biological transformation of organic matter by bacteria and zooplankton does not appear to cause significant changes to the ratio of C37:2 and C37:3 alkenones, but there are major alterations in the relative composition of alkenoates. Studies of water column processes and postdepositional …

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Alteration Processes Of Alkenones And Related Lipids In Water Columns And Sediments, H. Rodger Harvey Aug 2000

Alteration Processes Of Alkenones And Related Lipids In Water Columns And Sediments, H. Rodger Harvey

OES Faculty Publications

Alkenones produced by the haptophyte algae are currently being used as indices of sea surface temperature in recent and past ocean environments, but limited information is available concerning the impact of biotic and abiotic processes on the integrity of these long chain lipids. This synthesis provides selected background information on major alteration processes that must be considered before such indices can be used with confidence. A number of processes in the water column and surface sediments have the potential to impact the structural integrity of alkenones and compromise their ability as temperature markers. Processes discussed include the alteration of alkenone …

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The Biogeochemical Cycling Of Dissolved Organic Nitrogen In Estuarine Sediments, David J. Burdige, Shilong Zheng Jan 1998

The Biogeochemical Cycling Of Dissolved Organic Nitrogen In Estuarine Sediments, David J. Burdige, Shilong Zheng

OES Faculty Publications

Benthic fluxes and pore-water profiles of dissolved organic nitrogen and carbon (DON and DOC, respectively) were determined in seasonal studies at contrasting sites in Chesapeake Bay. Pore-water dissolved organic matter (DOM) concentrations were elevated over bottom-water values, generally increased with depth, and ranged from 15 to similar to 160 μM for DON and ~200-2000 μM for DOC. Pore-water DOM concentrations and the C:N ratio of this material showed spatial (depth) and temporal changes that varied among the sites studied. These trends appeared to be related to differences in the types of sediment organic matter (SOM) undergoing remineralization, as well as …

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A Geochemical Study Of Marine Sediments From The Mac. Robertson Shelf, East Antarctica: Initial Results And Palaeoenvironmental Implications, Peter N. Sedwick, P. T. Harris, L. G. Robertson, G. M. Mcmurtry, M. D. Cremer, P. Robinson Jan 1998

A Geochemical Study Of Marine Sediments From The Mac. Robertson Shelf, East Antarctica: Initial Results And Palaeoenvironmental Implications, Peter N. Sedwick, P. T. Harris, L. G. Robertson, G. M. Mcmurtry, M. D. Cremer, P. Robinson

OES Faculty Publications

Sediments from the Antarctic continental margin may provide detailed palaeoenvironmental records for Antarctic shelf waters during the late Quaternary. Here we present results from a palaeoenvironmental study of two sediment cores recovered from the continental shelf off Mac. Robertson Land, East Antarctica. These gravity cores were collected approximately 90 km apart from locations on the inner and outer shelf. Both cores are apparently undisturbed sequences of diatom ooze mixed with fine, quartz-rich sand. Core stratigraphies have been established from radiocarbon analyses of bulk organic carbon. Down-core geochemical determinations include the lithogenic components Al and Fe, biogenic components opal and organic …

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Fluxes Of Copper-Complexing Ligands From Estuarine Sediments, Stephen A. Skrabal, John R. Donat, David J. Burdige Jan 1997

Fluxes Of Copper-Complexing Ligands From Estuarine Sediments, Stephen A. Skrabal, John R. Donat, David J. Burdige

OES Faculty Publications

Most studies of the organic complexation of Cu in natural waters have focused on distributions and processes in the water column, where a significant fraction of Cu-complexing ligands may be biologically produced. We present direct evidence for a flux of Cu-complexing ligands from estuarine sediments, demonstrating that sediments are a significant, yet previously unrecognized source of the ligands. Fluxes of Cu-complexing ligands from Chesapeake Bay sediments range from 300 to 1,200 nmol m-2 d-1, exceeding fluxes of total dissolved Cu by 3->40-fold, suggesting that any Cu fluxing from the sediments is likely to be organically complexed. …

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Cluster Analysis Of Grain Size Parameters From A Beach Ridge Complex, Cape Henry, Virginia, Amy T. Robbins, G. Richard Whittecar Jan 1983

Cluster Analysis Of Grain Size Parameters From A Beach Ridge Complex, Cape Henry, Virginia, Amy T. Robbins, G. Richard Whittecar

OES Faculty Publications

Cape Henry is a Holocene beach ridge complex at the mouth of the Chesapeake Bay. Analyses of cross-cutting relationships visible on aerial photographs divide the complex into five geomorphic zones. Low, arcuate beach ridges, ornamented in places with small dunes, characterize the four oldest zones. The youngest zone consists of large irregular-shaped dunes which bury the margins of all older zones. Locations of 102 samples taken from 1 m depths on ridge crests were based upon a random stratified sampling grid covering all of Cape Henry. The use of half-phi size data generated standard sediment parameters. Weighted-pair cluster analyses of …

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Quaternary Sedimentation On The Inner Atlantic Shelf Between Cape Henry And Cape Hatteras: A Preliminary Report, Donald J. P. Swift, Gerald L. Shideler, Nicholas F. Avignone, Barry M. Holliday, Charles E. Dill Jr. Jan 1970

Quaternary Sedimentation On The Inner Atlantic Shelf Between Cape Henry And Cape Hatteras: A Preliminary Report, Donald J. P. Swift, Gerald L. Shideler, Nicholas F. Avignone, Barry M. Holliday, Charles E. Dill Jr.

OES Faculty Publications

The coast of the Middle Atlantic Bight of North America's Atlantic shelf consists of a series of spit - barrier island systems attached on their northern ends to eroding headlands. It has been suggested that these barriers were generated as coastwise-prograding spits (Fisher, 1967) or alternatively as mainland beaches detached by the Holocene rise of sea level (Hoyt, 1967). The shore face before the barriers consists of fine, seaward-fining sand. Locally, it is corrugated by oblique-trending ridges with up to 8 metres of relief — see for instance CSGS Chart 1109. Beyond the shore face lies a vast submarine sand …

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