珠江口盆地始新世—渐新世古环境演化及对冰期事件的响应OA

The Eocene-Oligocene climate experienced a temperature plunge event,which was global and accompanied by various significant environmental changes.As the formation of source rocks is often restricted by paleoclimate conditions,it is important for oil and gas exploration to ascertain the relationship between source rock formation and EOGM-type events.This research takes Eocene-Oligocene TOC data and changes of pollen and algae as the research content,to recover the Eocene-Oligocene paleoclimate changes in the Pearl River Mouth Basin.To this aim,we explore the coupling relationship between Eocene-Oligocene ice age events and basin climate,providing paleoclimatic evidence that supports oil and gas exploration in the basin.It was found that TOC data of the PY28-X1,EP21-X2,HZ20-X3,KP10-X4,and KP11-X5 wells have an obvious downward tendency near the Eocene-Oligocene boundary.A pollen study shows that the content of thermophilic pollen;i.e.,Quercoidites minutus,in the BY7-X6,BY13-X7,and LH29-X8 wells had an obvious downward tendency near the Eocene-Oligocene boundary.The pollen assemblages in the Oligocene Zhuhai Formation are dominated by temperate tree species,such as Alnipollenites,Momipites,and Pinuspollenites,which indicate that the climate of the Oligocene was cold.Finally,the paleoclimate and paleoenvironmental evolution from the Eocene to Oligocene in the Pearl River Mouth Basin are recovered,which allowed us to conduct a comparative analysis of the paleoclimate of major oil-gas-producing basins in offshore China in relation to global climate changes.The results show that there was an abrupt temperature decline in the Pearl River Mouth Basin and other major basins near the Eocene-Oligocene boundary,likely due as a response to the EOGM event.This abrupt drop corresponds to a decrease in TOC,indicating that EOGM-type events are not conducive to the formation of source rocks.