Author: Carlye D. Peterson
Publisher:
ISBN: 9781124994635
Category : Cycles
Languages : en
Pages : 172
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Book Description
Abstract: High-resolution seismic reflection records from the Santa Barbara basin suggest that much of the early Pleistocene hemipelagic sedimentary sequence records climate variability on orbital to sub-orbital scales, much like strata of the last glacial cycle studied at ODP Site 893. This thesis develops and tests a new method to extract lithologic cyclicity from high-resolution marine seismic reflection data (towed chirp) collected on the R/V Melville in 2008 that penetrate 10s of meters below seafloor into a {598}1 km-long sequence of south-dipping seismic reflections. Spectral analysis of these data reveals orbital-scale cyclicity in Pleistocene sediments that shifts to higher frequencies at the location of an unconformity. This analysis suggests that acoustic impedance and physical properties of sediment are controlled by climatically-driven oscillations in lithologic composition and fabric during deposition. Furthermore, shifts in spectral character permit identification of unconformities and changes in sedimentation rate prior to physical sampling by core. Cyclostratigraphic analysis of sedimentary sequences usually requires measurement of geochemical proxies on sediment material recovered from coring or drilling efforts which can be expensive and time-consuming. Seismic reflection data are a remotely sensed record of acoustic impedance contrasts in sediments which vary with sediment density and velocity changes imparted by organic matter fluctuations which are controlled by climate oscillations. With sufficient resolution, this method could allow remote detection of sedimentary cycles imparted by climate forces without retrieving sediments. Paleoclimatologically significant, orbital-scale cycles have been detected in marine seismic reflection data from the outer California Continental Borderland basins (Janik et al., 2004), Mediterranean outflow contourites (Llave et al., 2006), and the Cape Basin off southwest Africa (Weigelt and Uenzelmann-Neben, 2007). In Santa Barbara basin, where sediment character is documented to be sensitive to climatic variation at a sub-millennial scale, strata older than 1 Ma have been uplifted to the surface. These Pleistocene-age sediments dip to the south at {598}30° allowing for short core recovery and acquisition of high-resolution seismic reflection data at a constant shallow depth. Due to consistently high sedimentation rates in the basin (0.1-1 m/kyr), high-resolution seismic data such as the towed chirp seismic reflection data acquired on the 2008 R/V Melville Cruise allows detection of cycles as fine as {598}4 kyrs. Mid-way through the seismic section, an abrupt shift in spectral character illuminates the location of an otherwise unnoticeable unconformity, and the magnitude of the shift to lower frequencies suggests a sedimentation rate increase of {598}0.06 m/kyr. This method can be used to help with coring expeditions, to identify uninterrupted sedimentary successions for cyclic analysis, and to locate discontinuities in the sedimentary record.
Author: P. L. DeBoer
Publisher: John Wiley & Sons
ISBN: 1444304046
Category : Science
Languages : en
Pages : 583
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Book Description
Classically orbital cycles have been recognized in pelagic and lacustrine sequences characterized by quiet sedimentation, not disturbed by tectonics. Hoiwever, there is now increasing recognition that orbital cycles do influence climate and oceanography in general terms. There is also increasing acceptance of the possibility at least that the effect should be felt over large parts of the Earth's surface and that orbital cycles may well leave signs in other sedimentary environments that are commonly considered to be dominated by tectonics and eustasy. Containing thirty-one papers from a symposium held at the International Sedimentological Congress in Nottingham in 1990, this volume spans a range of topics from the astronomical theory behind orbital forcing, to field studies dealing with a broad range of sedimentary environments, and to modelling and simulation. State-of-the-art research papers. International expert authorship. The latest research in the highly topical subject of orbital forcing.
Author: Sara Afshar
Publisher:
ISBN: 9781267181381
Category : Climatic changes
Languages : en
Pages : 270
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Book Description
Abstract: Two high-resolution, multi-proxy records were produced for ~ 5-kyr windows at ~ 290 ka and ~ 735 ka, from piston cores acquired in Santa Barbara basin, California. These records show that abrupt, millennial- to sub-millennial-scale oscillations in weight % total organic carbon carbonate and, at lower resolution, biogenic silica, have occurred concurrent with climatic changes indicated by [delta]18O of planktonic foraminifera Globigerina bulloides. These oscillations are similar in magnitude and periodicity to the Dansgaard-Oeschger events observed at Ocean Drilling Program (ODP) Site 893 during Marine Isotopic Stage 3. In both records, the relationships in the proxies suggest higher sea-surface temperatures and productivity, associated with decreased benthic oxygenation during interstadials that, at least at ~ 290 ka, resulted in anoxic conditions. Combined with ODP Site 893 data, these records provide three almost equally spaced datums for studying high-frequency climate behavior and the sensitivity of oceanic biogeochemical responses since the Mid-Pleistocene Transition.
Author: Michael R. Rosen
Publisher: Springer Nature
ISBN: 3030665763
Category : Science
Languages : en
Pages : 592
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Book Description
This book honors the career of Professor Elizabeth Gierlowski-Kordesch who was a pioneer and leader in the field of limnogeology since the 1980s. Her work was instrumental in guiding students and professionals in the field until her untimely death in 2016. This collection of chapters was written by her colleagues and students and recognize the important role that Professor Gierlowski-Kordesch had in advancing the field of limnogeology. The chapters show the breadth of her reach as these have been contributed from virtually every continent. This book will be a primary reference for scientists, professionals and graduate students who are interested in the latest advances in limnogeologic processes and basin descriptions in North and South America, Europe, Africa, and China. *Free supplementary material available online for chapters 3,11,12 and 13. Access by searching for the book on link.springer.com
Author: Christopher C. Sorlien
Publisher:
ISBN:
Category : Basins (Geology)
Languages : en
Pages : 74
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Book Description
Author: P. L. DeBoer
Publisher: Wiley-Blackwell
ISBN: 9780632037360
Category : Science
Languages : en
Pages : 576
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Book Description
Classically orbital cycles have been recognized in pelagic and lacustrine sequences characterized by quiet sedimentation, not disturbed by tectonics. Hoiwever, there is now increasing recognition that orbital cycles do influence climate and oceanography in general terms. There is also increasing acceptance of the possibility at least that the effect should be felt over large parts of the Earth's surface and that orbital cycles may well leave signs in other sedimentary environments that are commonly considered to be dominated by tectonics and eustasy. Containing thirty-one papers from a symposium held at the International Sedimentological Congress in Nottingham in 1990, this volume spans a range of topics from the astronomical theory behind orbital forcing, to field studies dealing with a broad range of sedimentary environments, and to modelling and simulation. State-of-the-art research papers. International expert authorship. The latest research in the highly topical subject of orbital forcing.
Author: Laurence Robert Greene
Publisher:
ISBN:
Category :
Languages : en
Pages : 430
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Book Description
Author: Peter Eichhubl
Publisher:
ISBN:
Category : Diagenesis
Languages : en
Pages : 112
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Book Description
Author: E.L. LEITHOLD
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Author: Donn S. Gorsline
Publisher:
ISBN:
Category :
Languages : en
Pages : 12
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Book Description
Analysis of sediment cores yields a record of sedimentary history for the past 35,000 years and includes a complete cold to warm climate cycle. Sedimentation rates have been calculated using open ocean records as a dating tool plus some radiocarbon dates and data from micropaleontologic and oxygen isotopic data. These show that sedimentation rates have varied several fold and that the main effect is exerted by the terrigenous continental input. Pelagic biogenic input has also varied in parallel with the terrigenous contribution but at much lower rates. Organic carbon content parallels carbonate and shows a slight offset in terms of percent of total sediment due to terrigenous dilution and also to rapidity of burial. Slower rates over the past 6000 years have produced lower buried carbon values. Variations appear to be synchronous with the deep ocean record. (Author).
