Biotic community and landscape changes around the Eocene–Oligocene transition at Shapaja, Peruvian Amazonia: Regional or global drivers?
نویسندگان
چکیده
Since 2012, we have investigated a stratigraphic section encompassing the late Eocene–earliest Oligocene interval at Shapaja (Tarapoto area, Peruvian Amazonia, ca. 7°S), through paleontological and geological fieldwork. The measured sedimentary series (120 m-thick [West] plus 90 [East]), assigned to upper member of Pozo Formation, records fluvial micro-conglomeratic lenses intercalated with floodplain evaporite-rich fine red deposits, estuarine/coastal-plain tidally-influenced sandstones, oxbow lake nodule-rich blue clays. This shift coincides locally demise large Eocene coastal-plain wetland known as System. Eocene–early was extensively sampled for chemostratigraphy (?13C on dispersed organic matter pedogenic carbonate nodules), which in turn allowed refining location Eocene-Oligocene Transition (EOT) other climatic events recognized global scale (i.e., Oi-1 Oi-1a). has yielded nine fossil localities plant remains (leaves, wood, charophytes, palynomorphs), mollusks, decapods, and/or vertebrates (selachians, actinopterygians, lungfishes, amphibians, sauropsids, mammals), documenting ~130 distinct taxa. Four Formation predate EOT, one is clearly within while four are earliest/early age. small leaf impressions found along could be indicative dry seasonal conditions this region throughout after EOT. Monkeys, tropical rainforest environments, only recorded latest locality (TAR-21). Two biotic turnovers perceptible selachian, metatherian, rodent communities, well before EOT [~35–36 Ma] few hundred thousand years [~33 Ma]. latter turnover seems primarily related sea-level drop (ichthyofauna: marine-littoral elements replaced by obligate freshwater taxa) onset drier more climate early times (terrestrial components). Changes structure paleocommunities were mostly driven flexural subsidence during Eocene, then globally earliest deterioration.
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ژورنال
عنوان ژورنال: Global and Planetary Change
سال: 2021
ISSN: ['0921-8181', '1872-6364']
DOI: https://doi.org/10.1016/j.gloplacha.2021.103512