scholarly journals Pleistocene sediment offloading and the global sulfur cycle

2015 ◽  
Vol 12 (10) ◽  
pp. 3043-3060 ◽  
Author(s):  
S. Markovic ◽  
A. Paytan ◽  
U. G. Wortmann
Keyword(s):  
Sea Level ◽  
Considerable Increase ◽  
Sediment Accumulation ◽  
Sulfur Cycle ◽  
Sea Level Fluctuations ◽  
Sediment Budgets ◽  
Shelf Sediment ◽  
Continental Shelves ◽  
Shelf Sediments ◽  
Pleistocene Sediment

Abstract. Quaternary sea level fluctuations have greatly affected the sediment budgets of the continental shelves. Previous studies suggested that this caused a considerable increase in the net loss of shelf sediments. Since sediment accumulation and erosion are closely tied to the formation and re-oxidation of pyrite, we use a high-resolution record of sulfur isotope ratios (34S / 32S) of marine sulfate to evaluate the implications of the so-called "shelf sediment offloading" on the global sulfur cycle. Modeling of our δ34S record suggests that erosion during sea level lowstands was only partly compensated by increased sedimentation during times of rising sea level and sea level highstands. Furthermore, our data suggests that shelf systems reached a new equilibrium state about 700 ka, which considerably slowed or terminated shelf sediment offloading.

scholarly journals Pleistocene sediment offloading and the global sulfur cycle

2015 ◽  
Vol 12 (2) ◽  
pp. 1205-1245 ◽  
Author(s):  
S. Markovic ◽  
A. Paytan ◽  
U. G. Wortmann
Keyword(s):  
Sea Level ◽  
Considerable Increase ◽  
Sediment Accumulation ◽  
Sulfur Cycle ◽  
Sea Level Fluctuations ◽  
Sediment Budgets ◽  
Shelf Sediment ◽  
Continental Shelves ◽  
Shelf Sediments ◽  
Pleistocene Sediment

Abstract. Quaternary sea level fluctuations have greatly affected the sediment budgets of the continental shelves. Previous studies suggested that this caused a considerable increase in the net loss of shelf sediments. Since sediment accumulation and erosion are closely tied to the formation and re-oxidation of pyrite, we use a high resolution record of sulfur isotope ratios (34S / 32S) of marine sulfate to evaluate the implications of the so called "shelf sediment offloading" on the global sulfur cycle. Modeling of our δ34S record suggests that erosion during sea level lowstands was only partly compensated by increased sedimentation during times of rising sea level and sea level highstands. Furthermore, our data suggests that shelf systems reached a new equilibrium state about 700 kyr ago, which considerably slowed or terminated shelf sediment offloading.

Constraints on the amplitude of Mid-Pliocene (3.6–2.4 Ma) eustatic sea-level fluctuations from the New Zealand shallow-marine sediment record

2008 ◽  
Vol 367 (1886) ◽  
pp. 169-187 ◽  
Author(s):  
Tim R Naish ◽  
Gary S Wilson
Keyword(s):  
New Zealand ◽  
Sea Level ◽  
Sediment Accumulation ◽  
Ice Sheet ◽  
Deep Ocean ◽  
Antarctic Ice Sheet ◽  
Shallow Marine ◽  
Sea Level Fluctuations ◽  
Late Neogene ◽  
Sea Level Oscillations

Ice-volume calibrations of the deep-ocean foraminiferal δ 18 O record imply orbitally influenced sea-level fluctuations of up to 30 m amplitude during the Mid-Pliocene, and up to 30 per cent loss of the present-day mass of the East Antarctic Ice Sheet (EAIS) assuming complete deglaciation of the West Antarctic Ice Sheet (WAIS) and Greenland. These sea-level oscillations have driven recurrent transgressions and regressions across the world's continental shelves. Wanganui Basin, New Zealand, contains the most complete shallow-marine Late Neogene stratigraphic record in the form of a continuous cyclostratigraphy representing every 41 and 100 ka sea-level cycle since ca 3.6 Ma. This paper presents a synthesis of faunally derived palaeobathymetric data for shallow-marine sedimentary cycles corresponding to marine isotope stages M2–100 ( ca 3.4–2.4 Ma). Our approach estimates the eustatic sea-level contribution to the palaeobathymetry curve by placing constraints on total subsidence and decompacted sediment accumulation. The sea-level estimates are consistent with those from δ 18 O curves and numerical ice sheet models, and imply a significant sensitivity of the WAIS and the coastal margins of the EAIS to orbital oscillations in insolation during the Mid-Pliocene period of relative global warmth. Sea-level oscillations of 10–30 m were paced by obliquity.

Insolation-paced sea level during the Early Pleistocene, Taiwan

2021 ◽  
Author(s):  
Romain Vaucher ◽  
Shahin E. Dashtgard ◽  
Chorng-Shern Horng ◽  
Christian Zeeden ◽  
Antoine Dillinger ◽  
...  
Keyword(s):  
Sea Level ◽  
Benthic Foraminifera ◽  
Sediment Accumulation ◽  
Sediment Flux ◽  
Early Pleistocene ◽  
Glacial Cycles ◽  
Shallow Marine ◽  
Sea Level Fluctuations ◽  
Summer Insolation ◽  
O Isotope

<p>The Pleistocene was a phase of global cooling of the Earth through which glacial-interglacial cycles occurred, and the growth and decay of the ice-sheets resulted in quasi-cyclic sea-level fluctuations driven by orbital forcing. Despite that summer insolation is mostly controlled by precession, the records of the glacial cycles showcase a significant periodicity of ~41 kyrs during the Early Pleistocene forced by Earth’s obliquity (tilt) that varies the latitudinal distribution of insolation especially in high latitudes. The dominance of obliquity over precession in marine archives is commonly attributed to the in-phase effect of obliquity-related insolation versus the opposite-phased influence of precession, which may cancel out the summer insolation signal received by the southern and northern hemispheres.</p><p>Here, we present a clastic shallow marine record from the Cholan Formation (Early Pleistocene; Taiwan). Facies analysis indicates that quasi-cyclic deposition occurred in shoreface to offshore environments in the paleo-Taiwan Strait. The magnetobiostratigraphic framework indicates that the studied section occurs in the lower part of the Matuyama subchron (1.925 - 2.595 Ma) close to the lower limit of the Olduvai (1.925 Ma) normal polarity subchron. Comparison of the stratigraphy to a d<sup>18</sup>O isotope record of benthic foraminifera and orbital curves of precession and obliquity at the time of sediment accumulation reveals a good correlation between depositional cycles and the Northern Hemisphere summer insolation, demonstrating precession dominated sea-level fluctuations during the Early Pleistocene. These results underpin recent findings suggesting that d<sup>18</sup>O isotope records of benthic foraminifera have a more significant precession signal than previously described. This study also demonstrates that shallow-marine stratigraphic successions in high-accommodation and high-sedimentation basins can be outstanding climate archives, possibly even preserving sediment flux responding to half-precession cycles.</p>

Generation times and the Quaternary evolution of reef-building corals

Paleobiology ◽  
1984 ◽  
Vol 10 (1) ◽  
pp. 48-58 ◽  
Author(s):  
D. C. Potts
Keyword(s):  
Sea Level ◽  
High Frequency ◽  
Average Duration ◽  
Late Pliocene ◽  
Sea Level Fluctuations ◽  
Local Populations ◽  
Continental Shelves ◽  
Generation Times ◽  
Speciation Rates ◽  
Evolutionary Consequences

Faunal stasis among Indo-Pacific reef-building corals is explained as the result of chronic environmental disruptions preventing evolutionary processes from approaching completion since the Late Pliocene. The model assumes shallow reefal habitats (<20 m) on the continental shelves are major sites of scleractinian evolution and explores ecological and evolutionary consequences of high-frequency sea-level fluctuations and their associated transgression-regression cycles. Because single generations, dominated by a few large clonal genotypes, may persist indefinitely, local populations may not have experienced enough generations to approach evolutionary equilibrium with their environments during the estimated average duration (≈3200 yr) of existence of shallow habitats. Persistent consequences of chronic evolutionary disturbance may be the extensive intraspecific variation so characteristic of the dominant genera of shallow Indo-Pacific corals and the apparent paucity of recently evolved endemic species. The same disturbances may have accelerated speciation rates among reefal organisms with much shorter generation times.

scholarly journals Phanerozoic cycles of sea-level change on the Arabian Platform

GeoArabia ◽  
2005 ◽  
Vol 10 (2) ◽  
pp. 127-160 ◽  
Author(s):  
Bilal U. Haq ◽  
Abdul Motaleb Al-Qahtani
Keyword(s):  
Sea Level ◽  
Time Scale ◽  
Sediment Accumulation ◽  
Arabian Plate ◽  
Sea Level Changes ◽  
Sequence Stratigraphic ◽  
Sea Level Fluctuations ◽  
Regional Sea Level ◽  
Global Sea Level ◽  
Arabian Platform

ABSTRACT The Arabian Plate has experienced a complex tectonic history while also being widely influenced by eustatic sea-level changes. These diastrophic events either affected changes in the rate and/or location of subsidence that in turn led to the creation of significant new sedimentary accommodation, or caused major erosional hiatuses. As a result, both eustasy and tectonics have played important roles in the development of sedimentary sequences and in determining the locus and characteristics of reservoir, source and seal facies on the Arabian Platform. Here, we present a synthesis (Cycle Chart) of the regional sea-level fluctuations affecting the Platform that is based on Phanerozoic epi- and peri-Platform sequence-stratigraphic data. Information used for the synthesis includes sections from Saudi Arabia, Kuwait, the Greater Gulf area, Oman and Yemen. The regional Cycle Chart incorporates interpreted sedimentary onlap patterns on the margins of the Arabian Platform, as well as models of regional sea-level fluctuations that controlled these patterns. These are compared to eustatic data that represents the ‘global-mean’ models of sea-level changes, largely at second-order cycle level for the Paleozoic and third-order cycle level for the Mesozoic and Cenozoic eras. The comparisons reveal that Phanerozoic sediment accumulation patterns on the Platform were broadly controlled by eustasy, with a strong overprint of tectonics for several long intervals. During periods of tectonic quiescence, however, correlations with the eustatic events improve significantly. Thus, for example, during the Cambrian through early Silurian and mid Jurassic through early Paleogene intervals eustasy may have been the significant controlling factor for sedimentary patterns when long-term trends in both regional and global sea-level curves show similarities. The use of the Cycle Chart could facilitate exploration efforts on the Arabian Platform, provide better chronostratigraphic estimates and global correlations, and prove a useful accompaniment for sequence-stratigraphic studies. This integrative effort was greatly facilitated by the recent publication of the sequence stratigraphic synthesis of the Arabian Plate. The ages of Maximum Flooding Surfaces, however, have been recalibrated to the new (GTS 2004) time scale. This synthesis also represents a new recalibration of the Mesozoic and Cenozoic eustatic curves of Haq et al. (1988) to an up-to-date numerical time scale (GTS 2004).

scholarly journals Spatial distribution of water level impact to back-barrier bays

2018 ◽  
Author(s):  
Alfredo L. Aretxabaleta ◽  
Neil K. Ganju ◽  
Zafer Defne ◽  
Richard P. Signell
Keyword(s):  
Water Level ◽  
Sea Level ◽  
Water Levels ◽  
Analytical Models ◽  
Barnegat Bay ◽  
Sea Level Fluctuations ◽  
Flooding Hazard ◽  
Short Period ◽  
Inlet Geometry ◽  
Spatial Estimates

Abstract. Water level in semi-enclosed bays, landward of barrier islands, is mainly driven by offshore sea level fluctuations that are modulated by bay geometry and bathymetry, causing spatial variability in the ensuing response (transfer). Local wind setup can have a secondary role that depends on wind speed, fetch, and relative orientation of the wind direction and the bay. Inlet geometry and bathymetry primarily regulate the magnitude of the transfer between open ocean and bay. Tides and short-period offshore oscillations are more damped in the bays than longer-lasting offshore fluctuations, such as storm surge and sea level rise. We compare observed and modeled water levels at stations in a mid-Atlantic bay (Barnegat Bay) with offshore water level proxies. Observed water levels in Barnegat Bay are compared and combined with model results from the Coupled Ocean–Atmosphere–Wave–Sediment Transport (COAWST) modeling system to evaluate the spatial structure of the water level transfer. Analytical models based on the dimensional characteristics of the bay are used to combine the observed data and the numerical model results in a physically consistent approach. Model water level transfers match observed values at locations inside the Bay in the storm frequency band (transfers ranging from 70–100 %) and tidal frequencies (10–55 %). The contribution of frequency-dependent local setup caused by wind acting along the bay is also considered. The approach provides transfer estimates for locations inside the Bay where observations were not available resulting in a complete spatial characterization. The approach allows for the study of the Bay response to alternative forcing scenarios (landscape changes, future storms, and rising sea level). Detailed spatial estimates of water level transfer can inform decisions on inlet management and contribute to the assessment of current and future flooding hazard in back-barrier bays and along mainland shorelines.

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