北部湾盆地始新世古环境演化及沉积学意义  

Paleoenvironmental evolution and sedimentological significance of the Beibuwan Basin in the Eocene

作　　者：黄侠超 钟瀚霆 曹海洋[1,3] 肖伶俐 陈莹 王文楷 常晓琳[1,2,3] 刘欣春[1,2,3] 王琛宇 高凌雪 侯明才[1,2,3] HUANG Xiachao;ZHONG Hanting;CAO Haiyang;XIAO Lingli;CHEN Ying;WANG Wenkai;CHANG Xiaolin;LIU Xinchun;WANG Chenyu;GAO Lingxue;HOU Mingcai(Key Laboratory of Deep-time Geography&Environment Reconstruction and Applications of Ministry of Natural Resources,Chengdu University of Technology,Chengdu 610059,China;Institute of Sedimentary Geology,Chengdu University of Technology,Chengdu 610059,China;State key Laboratory of Oil and Gas Reservoir Geology and Exploitation(Chengdu University of Technology),Chengdu 610059,China;CNOOC Research Institute Ltd.,Beijing 100028,China;College of Resources and Envinonment,Xichang University,Xichang 615000,China)

机构地区：[1]自然资源部深时地理环境重建与应用重点实验室(成都理工大学),成都610059 [2]成都理工大学沉积地质研究院,成都610059 [3]油气藏地质及开发工程全国重点实验室(成都理工大学),成都610059 [4]中海油研究总院有限责任公司,北京100028 [5]西昌学院资源与环境学院,四川西昌615000

出　　处：《成都理工大学学报（自然科学版）》2024年第2期193-209,共17页Journal of Chengdu University of Technology: Science & Technology Edition

基　　金：中海石油有限公司科研项目(YXKY-ZX 012021)。

摘　　要：保存在地层中的孢粉化石是研究古植被、古气候变化的关键对象之一,对于重建古环境、预测烃源岩富集、指导油气勘探具有重要意义。本研究选取中国南海北部湾盆地乌石凹陷的WS-X1井、WS-X2井、海中凹陷的WZ-X3井、福山凹陷的JH-X4井始新世时期的孢粉进行分析,以揭示北部湾盆地始新世植被特征及其反映的古环境演化。研究共发现孢粉化石4大类共49个孢粉类型,以被子植物花粉占优势,其中栎粉Quercoidites(microhenrici+minutus)、三沟粉Tricolpopollenites、桤木粉Alnipollenites含量较高;裸子植物中以松粉Pinuspollenites为主;蕨类植物孢子以水龙骨单缝孢Polypodiaceaesporites、紫萁孢Osmundacidites为主;同时出现大量藻类,以盘星藻Pediastrum为主。4口井中,始新世亚热带类群丰富且花粉含量高,孢粉组合反映了北部湾盆地该时期发育以常绿栎类丰富为特征的林地,盆地低山地带发育常绿和落叶阔叶混交林为主的森林植被,林下为蕨类植被,指示了北部湾盆地始新世时期为温暖湿润的热带—亚热带气候。始新世早期分布的喜热植被较晚期更多,且在始新世晚期出现喜温的植被,推测始新世早期到晚期气候呈逐渐变凉的趋势。此外,孢粉组合中出现大量藻类,推测当时的沉积环境主要以湖泊和滨海的河流沼泽相为主。通过对北部湾盆地始新世时期的孢粉资料进行分析,为该盆地始新世时期的气候研究提供了更多依据。Sporopollenin fossils preserved in strata are important for studying ancient vegetation and climate change.They can be used to reconstruct the ancient environment,predict the enrichment of the source rocks for hydrocarbons,and guide oil and gas exploration.In this study,we considered the WS-X1 and WS-X2 wells in the Wushi Sag of the Beibuwan Basin in the South China Sea,WZ-X3 well in the Haizhong Sag,and JH-X4 well in the Fushan Sag to analyze the data on sporopollenins from the Eocene period,and identify the characteristics of vegetation of the Beibuwan Basin and its paleoenvironmental evolution.We identified 49 types of sporopollenin fossils belonging to four major categories that were dominated by angiospermic pollens.Quercoidites(microchrici+minutus),Tricolpopollenites,and Alnipollenites were found to have higher content in oak pollens.Pinuspollenites were the main pollen in gymnosperms,while the spores of ferns were mainly Polypodiaceae and Osmundacites.A large number of algae were observed,most of which were the disk-shaped Pediastrum.The four wells considered here were abundant in subtropical taxa,and had had a high pollen content during the Eocene,which reflected the development of forests that were characterized by abundant evergreen species of oak in the Beibuwan Basin in this period.Forest vegetation mainly consisted of evergreen and deciduous broad-leaved mixed forests in the low mountain areas of the basin,with fern vegetation below it indicating a warm and humid tropical-subtropical climate during the Eocene.Thermophilic vegetation was more widely distributed in the Early Eocene than in the Late Eocene.We think that the climate of the area cooled gradually trend from the Early to the Late Eocene.In addition,a large volume of algae appeared in the sporopollenin assemblage,indicating that the sedimentary environment at the time had been dominated by lake and coastal river swamp facies.

关 键 词：始新世 孢粉 古气候 古植被 北部湾盆地 

分 类 号：P52[天文地球—古生物学与地层学]