Vegetation and Organic‐Walled Phytoplankton at the End of the Antarctic Greenhouse World: Latest Eocene Cooling Events

摘要: Tecton Specia Copyr 10.102 The NBP0602A-3C SHALDRIL section collected in the Weddell Sea recovered a key stratigraphic interval that captured response of plants and organic-walled phytoplankton during first marked increase δO followed by large reduction atmospheric CO2 late Eocene around 36 Ma. Well-preserved palynomorphs from situ shelf sediments provide evidence cooling event sea level drop Terrestrial indicate at time deposition, southern beech-dominated conifer forest vegetation was abundant but with lower diversity signifying colder climates than for most La Meseta Formation on Seymour Island. marine palynomorph assemblage is dominated Vozzhennikovia apertura. This low-diversity, high-dominance dinoflagellate cyst also sign deteriorating conditions. Particularly notable uppermost samples reworked dinoflagellates acritarchs Cretaceous age. suggests significant erosion redeposition nearby Campanian-Maastrichtian sections level. Based biostratigraphy single isotopic date, it likely subsequent lowering can be correlated to brief spike δO-enriched values shown Zachos et al. (2001) curve Priabonian. According (2008), this occurs when lowest carbon dioxide concentrations were between 600 980 ppmv, giving us some perspectives as what could expected current concentration least doubled.