Eocene sporopollen assemblage from Ramree Island, Myanmar and its palaeoenvironment significance

Abstract

In order to support the oil and gas exploration in China-Burma cooperation block M and determine the age and sedimentary environment of the oil and gas bearing strata in Ramree Island of this block, a total of 10 source rock samples were collected for sporopollen analysis from the interval 2 562-2 844 m of well R-3 in Ramree Island, Burma. Abundant sporopollen fossils were found in each sample through observation, and 135 species attributable to 85 genera or undetermined species were identified. The sporopollen fossils in this interval are rich in Momipites and Quercoidites, with Sabalpollenites areolatus, a common molecule in Eocene, appearing intermittently, and characterized by Schizaeoisporites eocenicus. Based on the distribution patterns of sporopollen characteristic molecules and dominant genera and species, one sporepollen assemblage was recognized, namely Schizaeoisporites eocenicus-Quercoidites-Momipites-Sabalpollenites areolatus. By comparing the distribution ages of foraminifers and coccolithus nannofossils in the same interval, it was inferred that the age of sporepollen assemblage was the middle to late Eocene. According to the characteristics of the sporepollen assemblage, the statistical results of Paleogene to Neogene sporopollen sequence data in China's oil and gas regions, three models for the classification of sporopollen plant types, temperature zones and dry and humid zones established after systematic research, and distribution characteristics of other palynological fossils, we interpret that the study area was offshore land paleoenvironment with subtropical and warm temperate humid paleoclimate in the middle to late Eocene.

Keywords

• sporopollen assemblage
• paleoenvironment
• middle to late eocene
• ramree island
• burma