云南剑川盆地古近纪沙漠沉积特征和古风向重建  

Sedimentary characteristics of the Paleogene desert in Jianchuan basin, Yunnan, and palaeowind direction reconstruction

作　　者：江卓斐[1,2] 伍皓 崔晓庄[1,2] 江新胜[1,2] JIANG Zhuofei;WU Hao;CUI Xiaozhuang;JIANG Xinsheng(Chengdu Center of China Geological Survey,Chengdu,610081;Key Laboratory of Sedimentary Basin and Oil and Gas Resources,Ministry of Natural Resource,Chengdu,610081)

机构地区：[1]中国地质调查局成都地质调查中心,成都610081 [2]自然资源部沉积盆地与油气资源重点实验室,成都610081

出　　处：《地质论评》2019年第6期1487-1500,共14页Geological Review

基　　金：西南主要成矿带铀矿资源调查项目(编号:DD20190122)的成果~~

摘　　要：气候模拟显示,中国在古近纪曾被带状干旱带控制并被大面积沙漠沉积覆盖,然而在中国境内,尤其是在青藏高原周边气候变化与青藏高原隆升耦合敏感地区却鲜有发现,一定程度制约了东亚季风起源时间和气候变化研究.本文通过岩性、沉积结构、沉积构造、石英砂颗粒表面特征、铁质黏土套的化学成分特征和风成沙丘分布面积综合分析,证实了剑川盆地古近系始新统宝相寺组中段典型沙漠沉积的存在.古风向重建显示,沙漠早期为西风控制,晚期为西北风控制并伴随有初始季风雨.综合分析区域地质证据可见,青藏高原东缘始新世中晚期经历了一个由干旱到潮湿的气候剧变事件,而沙漠的消失即为该事件的标志.研究区古近纪风向偏转、初始季风雨的出现以及沙漠的消失表明,东亚季风可能始于晚始新世.本文进一步确证了青藏高原东缘古近纪沙漠的存在,对深化研究东亚季风起源的时间及其与青藏高原隆升的耦合关系具重要意义.A simulation has suggested that China was controlled by a zonal arid belt and covered by a large area of desert deposits during the Palaeogene.However,little of these deposits have been identified in China,especially in areas surrounding the Xizang(Tibetan)Plateau,where was sensitive to the coupling of climate change and plateau uplift.To extent,it has restricted the studies on the origin time of the Eastern Asian Monsoon and climate change.Based on comprehensive analyses on lithology,texture,structure,quartz sand grain surface characteristics,chemical composition of ferreous clay coatings and distribution area of aeolian dune,it has been verified that there were typical desert deposits occurred in the middle sequence of the Eocene Baoxiangsi Formation in the Jianchuan Basin,Yunnan Province.Paleowind direction reconstruction shows that the desert can be subdivided into tow stages.The earlier stage was controlled by westerly and later stage was controlled by northwesterly accompanied with initial monsoon rain marked by rain prints on dune surfaces.Combined with the regional geological records,it seems that there was a drastic climatic change from arid to humid in the southeastern margin of the Xizang Plateau between the Middle Eocene and Late Eocene and the extinction of the Eocene desert was its symbol.The wind direction rotation,appearance of initial monsoon rain and disappearance of the desert indicate that the Eastern Asian Monsoon System had begun at the Late Eocene.Consequently,this paper has further confirmed the Palaeogene desert existence in the southeastern margin of the Xizang Plateau and it is valuable for the study on the origin time of the Eastern Asian Monsoon and the coupling relationship between the uplifting of the Xizang Plateau and the upset of the Eastern Asian Monsoon.

关 键 词：古近纪沙漠 宝相寺组 青藏高原 古风向重建 东亚季风 

分 类 号：G63[文化科学—教育学]