Early Cretaceous stratigraphy, depositional environments, sandstone provenance, and tectonic setting of central Tibet, western China

Abstract

Research Article| September 01, 2004 Early Cretaceous stratigraphy, depositional environments, sandstone provenance, and tectonic setting of central Tibet, western China Kai-Jun Zhang; Kai-Jun Zhang 1Guangzhou Institute of Geochemistry, Laboratory of Marginal Sea Geology, Chinese Academy of Sciences, Guangzhou 510640, China2State Key Laboratory of Mineral Deposit Research, Department of Earth Sciences, Nanjing University, Nanjing 210093, China Search for other works by this author on: GSW Google Scholar Bang-Dong Xia; Bang-Dong Xia 3Department of Earth Sciences, Nanjing University, Nanjing 210093, China Search for other works by this author on: GSW Google Scholar Guan-Min Wang; Guan-Min Wang 4Department of Resources, University of Petroleum, Dongying, Shandong 257062, China Search for other works by this author on: GSW Google Scholar Yong-Tie Li; Yong-Tie Li 5Research Institute of Petroleum Exploration and Development, PetroChina Company Limited, Beijing 100083, China Search for other works by this author on: GSW Google Scholar He-Fei Ye He-Fei Ye 5Research Institute of Petroleum Exploration and Development, PetroChina Company Limited, Beijing 100083, China Search for other works by this author on: GSW Google Scholar GSA Bulletin (2004) 116 (9-10): 1202–1222. https://doi.org/10.1130/B25388.1 Article history received: 21 Apr 2003 rev-recd: 27 Nov 2003 accepted: 29 Dec 2003 first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Kai-Jun Zhang, Bang-Dong Xia, Guan-Min Wang, Yong-Tie Li, He-Fei Ye; Early Cretaceous stratigraphy, depositional environments, sandstone provenance, and tectonic setting of central Tibet, western China. GSA Bulletin 2004;; 116 (9-10): 1202–1222. doi: https://doi.org/10.1130/B25388.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract The period following Late Jurassic continental collision but preceding Late Cretaceous–Cenozoic arc magmatism represents a significant, yet poorly understood tectonic transition in central Tibet, western China. The Asa basin (31°00′–32°40′, 84°30′–87°05′) in central Tibet, which crosses the southern margin of the Qiangtang block, the Bangong-Nujiang suture zone, and the northern half of the Lhasa block, is characterized by up to 5000 m of continental-marine clastic-carbonate sediments and is ideally positioned to provide constraints on this transition. Sedimentary and volcanic data from recent field studies suggest that contraction controlled Berriasian-Valanginian tectonics, whereas back-arc extension may have controlled Hauterivian–Early Cenomanian basin evolution.Berriasian-Valanginian strata occur over the northern half of the Asa basin (approximately north of 31°40′) and unconformably overlie a varied basement. Sediment transport and fining directions are generally toward the south. The sandstones (Q78F11L11, Qm72F11Lt17, Qp38Lvm8Lsm54) in the central Bangong-Nujiang suture zone are dominated by monocrystalline quartz grains with undulose extinction but also contain abundant chert grains and some ultrabasic lithic fragments and radiolarian fragments. Hauterivian–Lower Barremian strata are characterized by siliciclastic rocks deposited in high-energy tidal environments, and barrier-bank skeletal bioclastic grainstone and wackestone. Intraformational limestone breccia or conglomerate and bimodal volcanic rocks are in places found within the sedimentary sequences in the southern margin of the basin (approximately south of 31°35′). Sandstones (Q54F20L26, Qm45F20Lt35, Qp20Lvm59Lsm21) are characterized by complex derivations from both recycled orogen and volcanic arc provenances. Widespread thick carbonate is a characteristic feature of Upper Barremian–Lower Cenomanian lithofacies, possibly formed in both restricted platform and platform interior environments. Lithic fragments in the sandstones (Q34F24L42, interbedded Qm33F24Lt43, Qp3Lvm87Lsm10) with the carbonates predominantly reflect volcanic source areas (65%).The Berriasian-Valanginian sequence is interpreted to represent molasse sediments from a northern orogen and indicates that the collision between the Qiangtang and Lhasa blocks could have extended into the Valanginian. The change from orogenic to magmatic arc source areas for sandstones during the beginning of the Hauterivian, along with a coeval extensive marine transgression in central-southern Tibet, normal faulting, and rich intercalations of bimodal volcanic rocks, are interpreted to be related to back-arc extension of the Gangdese arc during the Middle Cretaceous (ca. 120–95 Ma). This may have occurred in response to a rollback of the Tethyan oceanic slab. During the Middle Cretaceous, the entire southern Eurasian margin could have been characterized by a series of back-arc rift basins (including those in Kohistan and Ladakh). Some basins may have been floored by oceanic crust whereas others remained underlain by continental or transitional basement, much like the present western Pacific margin. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.