西藏南部吉隆盆地晚中新世-早更新世介形类群落研究  

Late Miocene-Early Pleistocene Ostracoda Fauna of Gyirong Basin , Southern Tibet

作　　者：陈奋宁[1] 陈锐明[1] 郭岐明 张克信[3,4] 周修高[4] 徐亚东[3,4] 江尚松[4] 

机构地区：[1]西安地质矿产研究所,西安710054 [2]陕西省地质调查中心,西安710016 [3]中国地质大学生物地质与环境地质国家重点实验室,武汉430074 [4]中国地质大学地球科学学院,武汉430074

出　　处：《地质学报》2013年第6期872-886,共15页Acta Geologica Sinica

基　　金：中国地质调查局国家青藏专项项目(编号1212010610103);国家自然科学基金青年基金(编号41102073);国家自然科学创新研究群体基金(编号40621002);中国地质调查局国家青藏专项项目(编号121201061012)共同资助的成果

摘　　要：本文在西藏南部吉隆盆地新生代沉积中获得丰富的介形类化石,根据介形类动物群在地层剖面上的分布规律,建立了8个介形类群落,自下而上为:Leucocytherella trinoda-Ilyocypris群落;Ilyocypris pentanada-Leucocytherella hyalina群落;Candoniella zadaensis-Leucocytherella群落;Eucypris subgyrongensis-Candoniella zadaensis群落;Leucocytherella-Cadoniella zadaensis群落;Leucocythere mirabilis-Leucocytherella hyalina群落;Leucocythere mirabilis-Leucocytherella glabra群落和Leucocythere mirabilis-Leucocytherella trinoda群落。通过对介形类群落进行详细的特征分析,并结合磁性地层年代学数据,将吉隆盆地7.2～1.67Ma的古气候划分为5个期次:①7.2～6.7Ma为暖湿期;②6.7～5.8Ma为凉湿期;③5.8～3.6Ma为暖湿期;④3.6～2.6Ma为凉湿期;⑤2.6～1.67Ma为冷干期。将研究区的7.2Ma以来的气候演化特征与全球气候演变对比认为:吉隆盆地7.2～5.8Ma间的气候以暖湿为主,可能与来自印度的东南季风加强有关;5.8～3.6Ma间吉隆盆地古气候分析显示为相对暖湿期,可能与来自印度洋的东南季风再次加强有关;3.6Ma后,由于是受全球气候变冷、冬季风加强及青藏高原强烈隆升的影响,吉隆盆地气候向更寒冷干旱的环境转变。Diverse ostracoda fossils were found in the Gyirong Basin , Southern Tibet.According to the distribution characteristics of the fossil succession , the ostracoda fauna in this area can be divided into 8 ostracoda communities.They are in ascending order as follows ： Leucocytherella trinoda-Ilyocypris community ; Ilyocypris pentanada-Leucocytherella hyalina community ; Candoniella-Leucocytherella community ; Eucypris subgyrongensis-Candoniella posterindinatacommunity ; Leucocytherella-Cadoniella zadaensis community ; Leucocythere mirabilis-Leucocytherella hyalinacommunity ; Leucocythere mirabilis Leucocytherella glabra community and Leucocythere mirabilis Leucocytherella trinoda community.After detailed analysis of the characteristics of ostracoda fauna and with the study of magnetostratigraphy , the characteristics of palaeoclimate during 7.2～1.67Ma can be divided into 5phases ： ① During7.2～6.7Ma , the climate was warm and humid ; ②during 6.7～5.8Ma , the climate became cool and humid ; ③During 5. 8～3.6Ma , the climate became warm and damp again ; ④ During 3.6～2.6Ma , the climate was much cooler and damp in the Gyirong Basin ; ⑤After 2.6Ma , the climate became much drier and colder.Comparison with the paleoclimate phases at the Woma section and global paleoclimate evolution concludes that the climate was mainly humid in the Gyirong Basin during 7.2～5.8Ma.This phenomenon may be related to strengthening of southwest monsoon from the Indian Ocean.There was cooling event in strengthening of southwest at the period of 6.7～5.8Ma.During 5.8～3.6Ma , the climate was relatively humid , and this may result from southeast monsoon resurface again.After 3.6Ma , the massive uplifting of Qinghai-Tibet plateau strengthened Asian monsoon , and this change may cause the climate change towards colder and drier in the Gyirong Basin.

关 键 词：中新世—早更新世 介形类群落 古气候演化 吉隆盆地 青藏高原 

分 类 号：Q915[天文地球—古生物学与地层学]