Cenozoic paleoceanography in the Indian Ocean: paleoceanographic biotic and abiotic changes before the development of monsoon system

We discusses the Cenozoic paleoceanographic events in the Indian Ocean, based on onxygen and carbon isotopes, benthic and planktonic foraminifera, radiolaria, and diatom, as follows: 1) extinction event of benthic foraminiferal assemblage co-occurred with the oxygen and carbon isotopic minimum event in the latest Paleocene; 2) step-wise faunal and floral changes during the middle to latest Eocene and the signals of cooling; 3) explosive evolution of planktonic fauna and flora co-occurred with oxygen isotopic positive shift in the early Oligocene and the formation of cryosphere; 4) gradual changes shown in the appearance and disappearance of microfossil taxa in relation to a global cooling and warming during the early to middle Miocene; 5) further cooling and the accumulation of organic matter as indicated in oxygen isotopic positive shift and carbon isotopic negative shift. These events occurred in close relation to the deformation and closing of the Thetyan Sea, development of the Antarctic ice sheet, deep-water circulation driven by either Northern Component Water or Southern Component Water and/or both, potential marine productivity related to upwelling, distribution changes of continents and closing of seaway, uplifting of the Himalayas and the Tibetan Plateau supply of weathered materials including nutrients to the ocean, and CO₂ content in atmosphere.