Abundances of shells of planktic foraminifera species in Upper Miocene sediments from the Indian Ocean and relative abundances of their groups

Locations of climatic zones at four time intervals during Miocene are reconstructed from ranges of planktic foraminifera shells in Miocene deposits of the Indian Ocean. Gradual cooling took place in the southern Indian Ocean during Miocene as a result of growth of the Antarctic glacial shield accompanied by migration of climatic zones toward the equator. Two warmer intervals (end of Early Miocene and Late Miocene) and two cooler periods (beginning of Early Miocene and end of Middle Miocene) are identified in the northern Indian Ocean. Climate of the Indian Ocean was warmer than at present throughout Miocene and climatic zones were located farther to the south than their present positions.