NOAA/WDS Paleoclimatology - Northern Gulf of Mexico Geochemistry, Lithology and Radiogenic Isotope Data over the last 3 Ma
This archived Paleoclimatology Study is available from the NOAA National Centers for Environmental Information (NCEI), under the World Data Service (WDS) for Paleoclimatology. The associated NCEI study type is Paleoceanography. The data include parameters of paleoceanography with a geographic location of Gulf Of Mexico, North Atlantic Ocean. The time period coverage is from 2809360 to 8070 in calendar years before present (BP). See metadata information for parameter and study location details. Please cite this study when using the data.
- Cite as: Portier, A.M.; Thierens, M.; Martin, E.E.; Hemming, S.R.; Gombiner, J.H.; Raymo, M.E. (2020-07-13): NOAA/WDS Paleoclimatology - Northern Gulf of Mexico Geochemistry, Lithology and Radiogenic Isotope Data over the last 3 Ma. [indicate subset used]. NOAA National Centers for Environmental Information. https://doi.org/10.25921/s77e-hw08. Accessed [date].
- Please refer to Credit tab for full citation information.
- doi:10.25921/s77e-hw08
- noaa-ocean-30492
- NCEI DSI 1200_02
- NCEI DSI 1200_01
noaa-ocean-30492
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Distributor | NOAA National Centers for Environmental Information
ncei.info@noaa.gov |
Dataset Point of Contact | NOAA National Centers for Environmental Information
ncei.info@noaa.gov |
Dataset Point of Contact | Data Center Contact
NOAA World Data Service for Paleoclimatology 828-271-4800 paleo@noaa.gov |
Coverage Description | Date Range: 2809360 cal yr BP to 8070 cal yr BP; |
Time Period | -2807410 to -6120 |
Spatial Bounding Box Coordinates |
N: 28.8317
S: 28.8317
E: -87.16
W: -87.16
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Spatial Coverage Map |
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Data Presentation Form | Digital table - digital representation of facts or figures systematically displayed, especially in columns
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Dataset Progress Status | Complete - production of the data has been completed |
Data Update Frequency | Data update frequency not available |
Supplemental Information |
STUDY NOTES: Grain size distribution, clay mineralogy, CIA*, K/Ar ages and Nd-Sr-Pb isotope geochemistry of Pleistocene clay detrital fractions (<2 µm) from ODP Site 625 in northeastern Gulf of Mexico. Updated data table and publication metadata submitted 26-Apr-2021. Provided Keywords: Mid-Pleistocene Transition, Laurentide Ice Sheet, Regolith Hypothesis, Mississippi Drainage Basin, Canadian Shield
ABSTRACT SUPPLIED BY ORIGINATOR: The regolith hypothesis attributes the inferred growth of a thicker and more voluminous Laurentide Ice Sheet (LIS) across the mid-Pleistocene transition (MPT) to the removal of softer subglacial substrates of either regolith or sedimentary cover and subsequent exposure of crystalline bedrock with higher basal friction at the base of the LIS. This hypothesis predicts that sediment derived from the LIS was dominated by weathered sources prior to the MPT and then transitioned to fresh Canadian Shield sources during and after the MPT. Here, we present clay mineralogy, modified indices of chemical alteration, K/Ar ages and radiogenic isotopes (Sr, Nd, Pb) of Pleistocene clay detrital fractions from ODP Site 625 in northeastern Gulf of Mexico to evaluate changes on glacial-interglacial and longer‐term timescales in sediment composition during the Pleistocene and test this prediction. Mineralogical and geochemical proxies show a predominance of chemically weathered clays (kaolinite and smectite with clay ratios ≥3.0) sourced from the Appalachians as determined by radiogenic isotopes and K/Ar ages throughout the site's three million‐year sediment record. This is consistent with extensive pre‐Pleistocene weathering of Caledonian‐Appalachian (∼450 Ma) material that covered North American cratonic sources within the Mississippi drainage basin. However, following the MPT, we observe a unique addition of physically‐weathered clays (chlorite and illite with clay ratios <3.0) with radiogenic isotopes and K/Ar ages indicating contributions from more ancient geological sources, most simply explained as sediment derived from physical erosion from the crystalline Canadian Shield. These observations are generally consistent with predictions made by the regolith hypothesis. |
Purpose | Records of past climate and ocean circulation derived from marine sediments. Parameter keywords describe what was measured in this dataset. Additional summary information can be found in the abstracts of papers listed in the dataset citations. |
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Theme keywords | Global Change Master Directory (GCMD) Science Keywords
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Data Center keywords | Global Change Master Directory (GCMD) Data Center Keywords
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Last Modified: 2023-09-01
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