Nannofossil palaeoecology of Lower Miocene sapropels from IODP Expedition 359, the Maldives
نویسندگان
چکیده
During IODP expedition 359 multiple holes recovered Modern to Middle Miocene sediments from the Kardiva Drift which is strongly influenced by monsoonally-driven currents. Two continued below drift into Lower that were deposited under rather different conditions following Oligocene subsidence of Maldives Ridge. These are characterised marked alternation between dark organic-rich sapropelic and pale nannofossil oozes. This interval also generally good excellent preservation. Nannofossil assemblages sapropel non-sapropel intervals broadly similar; both sediment types contain diverse normal marine no taxa confined either type. In sapropels abundance diversity tends be lower Cyclicargolithus floridanus specimens smaller. addition Umbilicosphaera abundances higher in layers whilst Discoaster most sapropels. differences more better developed The evidence supports interpretation geochemistry formation was primarily driven changes bottom water ventilation linked sea-level change than surface productivity. • Well-preserved described dated 21.5–24 Ma (Early end Oligocene). quantitatively those intervening beds. assemblage suggestive increased productivity during formation. Increased unlikely prime driver
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ژورنال
عنوان ژورنال: Palaeogeography, Palaeoclimatology, Palaeoecology
سال: 2021
ISSN: ['1872-616X', '0031-0182']
DOI: https://doi.org/10.1016/j.palaeo.2021.110325