Late Cretaceous Foraminiferal Faunas from the Saiqu“mélange”in Southern Tibet  

作　　者：LI Guobiao WAN Xiaoqiao JIANG Ganqing HU Xiumian GOUDEMAND Nicolas HAN Hongdou CHEN Xi 

机构地区：[1]Departmemt of Earth Sciences, China University of Geosciences, Xueyuan Lu 29, Beijing 100083, China [2]Department of Geosciences, Universi-ty ofNevada Las Vegas, Las Vegas NV89154-4010, US [3]Departmemt of Earth Sciences,Nanjing University, Nanjing 210093, China [4]Insitute of Paleontology and Museum, University of Zurich, Karl Schmid-Strasse 4, Zurich CH-8006, Switzerland

出　　处：《Acta Geologica Sinica(English Edition)》2007年第6期917-924,共8页地质学报（英文版）

基　　金：financially supported by the National Basic Research Program of China(973 Program,Grant No.2006CB701400);the Project of the Geological Survey of China(Grant Nos.H45C004004,G45C001004);the National Natural Science Foundation of China(Grant No.40472011).

摘　　要：As one of the mélanges in the southern side of the Yarlung-Zangbo suture zone, the Saiqu mélange in southern Tibet is important for understanding the evolution of the Neo-Tethys ocean. The age of the Saiqu mélange, however, has been debated due to the lack of reliable fossil evidence in matrix strata. Based on lithological similarities with platform strata in southern Tibet and limited fossils from exotic blocks, previous studies variously ascribed the Saiqu mélange to be Triassic in general, Late Triassic, or Late Cretaceous. Here we reported planktonic foraminiferal faunas from the matrix strata of the Saiqu mélange. The new fossils yield a Late Cretaceous age, which is so far the best age constraint for the mélange. Regional stratigraphic correlation indicates that the Cretaceous Oceanic Red Beds （CORBs） in Saiqu may be time equivalent to the CORBs of the Zongzhuo Formation in neighboring regions. Thus the Saiqu m^lange should be correlated to the Upper Cretaceous Zongzhuo Formation rather than the Triassic Xiukang Group, as previously suggested.As one of the mélanges in the southern side of the Yarlung-Zangbo suture zone, the Saiqu mélange in southern Tibet is important for understanding the evolution of the Neo-Tethys ocean. The age of the Saiqu mélange, however, has been debated due to the lack of reliable fossil evidence in matrix strata. Based on lithological similarities with platform strata in southern Tibet and limited fossils from exotic blocks, previous studies variously ascribed the Saiqu mélange to be Triassic in general, Late Triassic, or Late Cretaceous. Here we reported planktonic foraminiferal faunas from the matrix strata of the Saiqu mélange. The new fossils yield a Late Cretaceous age, which is so far the best age constraint for the mélange. Regional stratigraphic correlation indicates that the Cretaceous Oceanic Red Beds （CORBs） in Saiqu may be time equivalent to the CORBs of the Zongzhuo Formation in neighboring regions. Thus the Saiqu m^lange should be correlated to the Upper Cretaceous Zongzhuo Formation rather than the Triassic Xiukang Group, as previously suggested.

关 键 词：Saiqu Mélange Planktonic Foraminifera Late Cretaceous Red Beds Zongzhuo Formation Tibet 

分 类 号：Q915[天文地球—古生物学与地层学]