Sedimental Pollen Distribution in the Northeastern Indian Ocean and their Palaeo-Environmental Information

Abstract

Seabed sediments in the northeastern part of the Indian Ocean have preserved comprehensive information of the typical tropical oceans and ancient marine environment. Firstly, the sample of core 12I712 was used for paleoclimate reconstruction of the northeastern Indian Ocean. In zones A and B (45~36 ka BP) of the 12I712 core, tree pollen had a higher percentage. Combined with the high pollen concentration in A and B zones, this reflects the warm and humid climate of the resource areas, which was associated with a high sea level. The percentage of pollen of the trees in zones C and D (36 ~ 5 ka BP) decreased and the percentage of pollen of the herbaceous plants increased. The percentages of pollen from Betula and Alnus increased, reflecting the gradual transformation to a cold and dry climate with scarce vegetation and drought. Then, based on a fossil pollen analysis on two cores from the northeastern Indian Ocean and compared with fossil pollen results from the South China Sea, we determined that warm pools can be taken as a climate humidity index both in the South China Sea and the Indian Ocean. Pinus pollen can be taken as an index of sea level change; its percentage decreased in the low sea level period only in the cores near the continental shelf, and its percentage increased in the low sea level period in the cores in the northeastern Indian Ocean because they are in the deep sea.