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      Expedition 313 summary

      Expedition 313 Scientists
      Proceedings of the IODP
      Integrated Ocean Drilling Program

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          Abstract

          Integrated Ocean Drilling Program (IODP) Expedition 313 to the New Jersey Shallow Shelf off the east coast of the United States is the third IODP expedition to use a mission-specific platform. It was conducted by the European Consortium for Ocean Research Drilling (ECORD) Science Operator (ESO) between 30 April and 17 July 2009, with additional support from the International Continental Scientific Drilling Program (ICDP). There were three objectives: (1) date late Paleogene–Neogene depositional sequences and compare ages of unconformable surfaces that divide these sequences with times of sea level lowerings predicted from the δ18O glacio-eustatic proxy; (2) estimate the corresponding amplitudes, rates, and mechanisms of sea level change; and (3) evaluate sequence stratigraphic facies models that predict depositional environments, sediment compositions, and stratal geometries in response to sea level change. We drilled at three locations targeting the topsets, foresets, and toesets of several clinoforms. Seismic correlations to previously drilled holes on the continental slope and extrapolations of depths to key horizons in wells drilled into the adjacent coastal plain suggest the clinoform structures investigated during Expedition 313 were deposited during times of oscillations in global sea level; however, this needs to be determined with much greater certainty. The age, lithofacies, and core-log-seismic correlations provided by drilling at key locations will yield the data needed for a rigorous evaluation. We attempted 612 core runs with 80% recovery totaling 1311 m in length. Some or all of the upper 180–280 m of sand-prone sediment was drilled without coring. The deepest hole (M0029A) reached 757 mbsf, and the oldest sediment recovered was late Eocene (Hole M0027A). Wireline logs gathered spectral gamma ray, resistivity, magnetic susceptibility, sonic, and acoustic televiewer data; a vertical seismic profile was run at each site. Multisensor core logger (MSCL), natural gamma ray, and thermal conductivity measurements were made on all cores prior to splitting. Aided by physical properties of discrete samples measured onshore, we have established preliminary core-log-seismic ties with depth uncertainties typically ±7 m or less. We are confident that further study will narrow this range and firmly link facies successions to as many as 16 surfaces and/or sequence-bounding unconformities mapped in the regional seismic grid. Reliable zonations of multiple fossil groups, Sr isotopic ages measured on mollusks and foraminifers, and intervals of magnetic reversal chronology provide a nearly continuous composite record of ~1 m.y. sea level cycles (22–12 Ma). Shifts in climate on the adjacent coastal plain provide distinct pollen markers in all three holes and represent another correlation tool. We recovered regressive sediment bodies that are absent in onshore boreholes because of those updip locations. Lithofacies and benthic foraminifer assemblages provide a rich source of information concerning depositional setting and imply as much as 60 m water depth changes; calculations of sediment compaction, crustal loading, and other corrections need to be made before we can estimate the corresponding magnitudes of eustatic change. Large variations in pore water salinity appear to be controlled by lithofacies. Their sharp vertical gradients await explanation, and relationships to microbiologic communities that we recovered from unsplit cores have yet to be determined.

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          Most cited references38

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          Chronology of fluctuating sea levels since the triassic.

          Advances in sequence stratigraphy and the development of depositional models have helped explain the origin of genetically related sedimentary packages during sea level cycles. These concepts have provided the basis for the recognition of sea level events in subsurface data and in outcrops of marine sediments around the world. Knowledge of these events has led to a new generation of Mesozoic and Cenozoic global cycle charts that chronicle the history of sea level fluctuations during the past 250 million years in greater detail than was possible from seismic-stratigraphic data alone. An effort has been made to develop a realistic and accurate time scale and widely applicable chronostratigraphy and to integrate depositional sequences documented in public domain outcrop sections from various basins with this chronostratigraphic framework. A description of this approach and an account of the results, illustrated by sea level cycle charts of the Cenozoic, Cretaceous, Jurassic, and Triassic intervals, are presented.
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            The Phanerozoic record of global sea-level change.

            K. Miller (2005)
            We review Phanerozoic sea-level changes [543 million years ago (Ma) to the present] on various time scales and present a new sea-level record for the past 100 million years (My). Long-term sea level peaked at 100 +/- 50 meters during the Cretaceous, implying that ocean-crust production rates were much lower than previously inferred. Sea level mirrors oxygen isotope variations, reflecting ice-volume change on the 10(4)- to 10(6)-year scale, but a link between oxygen isotope and sea level on the 10(7)-year scale must be due to temperature changes that we attribute to tectonically controlled carbon dioxide variations. Sea-level change has influenced phytoplankton evolution, ocean chemistry, and the loci of carbonate, organic carbon, and siliciclastic sediment burial. Over the past 100 My, sea-level changes reflect global climate evolution from a time of ephemeral Antarctic ice sheets (100 to 33 Ma), through a time of large ice sheets primarily in Antarctica (33 to 2.5 Ma), to a world with large Antarctic and large, variable Northern Hemisphere ice sheets (2.5 Ma to the present).
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              A 20th century acceleration in global sea-level rise

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                Author and article information

                Journal
                10.2204/iodp.proc.313.2010
                Proceedings of the IODP
                Integrated Ocean Drilling Program
                1930-1014
                04 December 2010
                Article
                10.2204/iodp.proc.313.101.2010
                768956f5-4df2-47e8-a052-143395e357a4

                This work is licensed under a Creative Commons Attribution 4.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/

                History

                Earth & Environmental sciences,Oceanography & Hydrology,Geophysics,Chemistry,Geosciences

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