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doi:10.2204/iodp.proc.341.205.2019 Data report: calcareous nannofossils and bulk calcium carbonate measurements from IODP Expedition 341, Site U1418, Gulf of Alaska1Inva Braha,2, 3 Emily Hager-Hahn,4 and Leah J. LeVay2AbstractSite U1418 was cored on the Surveyor Fan in the Gulf of Alaska during Integrated Ocean Drilling Program (IODP) Expedition 341. A 949 m sedimentary sequence consisting of muds and diamicts was recovered. The uppermost ~266 m contained rare intermittent occurrences of calcareous nannofossils. This interval spans approximately the last 200 ky and potentially records environmental changes associated with glacial–interglacial cycles, making it useful for paleoceanographic reconstructions. In an effort to determine calcareous nannofossil productivity through this time interval, we studied the nannofossil assemblage and calcium carbonate (CaCO3) weight percentage of the sediments. The nannofossil assemblage was dominated by Gephyrocapsa species and Coccolithus pelagicus. Gephyrocapsa spp. were most abundant between ~100 and 266 m core composite depth below seafloor (CCSF-A). Shallower than 100 m, C. pelagicus composed at least half of the assemblage. Reworked specimens of Eocene–Oligocene age were consistently observed. CaCO3 content averaged 2.77 wt% and did not display any notable trends across the study interval. |
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