Cambrian stratigraphy and depositional history of the northern Indian Himalaya, Spiti Valley, north-central India

Abstract

Research Article| March 01, 2006 Cambrian stratigraphy and depositional history of the northern Indian Himalaya, Spiti Valley, north-central India Paul M. Myrow; Paul M. Myrow 1Department of Geology, Colorado College, Colorado Springs, Colorado 80903, USA Search for other works by this author on: GSW Google Scholar Karl R. Thompson; Karl R. Thompson 2Department of Earth Sciences, University of California, Riverside, California 92521, USA Search for other works by this author on: GSW Google Scholar Nigel C. Hughes; Nigel C. Hughes 2Department of Earth Sciences, University of California, Riverside, California 92521, USA Search for other works by this author on: GSW Google Scholar Timothy S. Paulsen; Timothy S. Paulsen 3Department of Geology, University of Wisconsin, Oshkosh, Wisconsin 54901, USA Search for other works by this author on: GSW Google Scholar Bryan K. Sell; Bryan K. Sell 4Department of Earth Sciences, University of California, Riverside, California 92521, USA Search for other works by this author on: GSW Google Scholar Suraj K. Parcha Suraj K. Parcha 5Wadia Institute of Himalayan Geology, Dehra Dun, Uttranchal 248001, India Search for other works by this author on: GSW Google Scholar Author and Article Information Paul M. Myrow 1Department of Geology, Colorado College, Colorado Springs, Colorado 80903, USA Karl R. Thompson 2Department of Earth Sciences, University of California, Riverside, California 92521, USA Nigel C. Hughes 2Department of Earth Sciences, University of California, Riverside, California 92521, USA Timothy S. Paulsen 3Department of Geology, University of Wisconsin, Oshkosh, Wisconsin 54901, USA Bryan K. Sell 4Department of Earth Sciences, University of California, Riverside, California 92521, USA Suraj K. Parcha 5Wadia Institute of Himalayan Geology, Dehra Dun, Uttranchal 248001, India Publisher: Geological Society of America Received: 27 Mar 2005 Revision Received: 01 Sep 2005 Accepted: 25 Oct 2005 First Online: 08 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (2006) 118 (3-4): 491–510. https://doi.org/10.1130/B25828.1 Article history Received: 27 Mar 2005 Revision Received: 01 Sep 2005 Accepted: 25 Oct 2005 First Online: 08 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 Paul M. Myrow, Karl R. Thompson, Nigel C. Hughes, Timothy S. Paulsen, Bryan K. Sell, Suraj K. Parcha; Cambrian stratigraphy and depositional history of the northern Indian Himalaya, Spiti Valley, north-central India. GSA Bulletin 2006;; 118 (3-4): 491–510. doi: https://doi.org/10.1130/B25828.1 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 Recent work on Himalayan tectonics indicates that prior to the Cenozoic collision of India and Asia, an enigmatic Cambrian–Ordovician event may have strongly influenced the regional geology of the Himalaya. Stratigraphic and sedimentological analyses of well-preserved Cambrian deposits are critical for understanding the nature of this early tectonic event and its influence on the later tectonic evolution of the Himalaya. The Parahio Formation, defined herein, of the Parahio Valley, Spiti region, in the Tethyan Himalaya of India, is the best biostratigraphically resolved section of Cambrian strata in the entire Himalaya. This formation consists of >1350 m of dominantly siliciclastic deltaic deposits. The formation ranges from uppermost Lower Cambrian (Lungwangmiaoan Stage) to middle Middle Cambrian (Hsuchuangian Stage), representing a time span of ∼5–10 m.y. It contains numerous medium-scale shoaling cycles that range from storm-influenced offshore deposits to thick trough cross-bedded fluvial facies. Many thin carbonate beds with abundant trilobite fossils directly overlie the fluvial facies and represent transgressive systems tract deposits. The cycles are interpreted to have resulted from delta-lobe switching, based on a lack of systematic stratigraphic changes in cycle or facies thicknesses. This paleoenvironmental reconstruction contradicts previous interpretations of this unit that range from deep-sea flysch to shallow-marine tidalites. In addition, our paleoenvironmental analysis and paleocurrent data suggest that the uppermost Lower to Middle Cambrian deposits of the Lesser and Tethyan Himalaya are parts of the same ancient northward-prograding, fluvial-deltaic depositional system of the paleo-Tethys margin of India.An angular unconformity with overlying Ordovician conglomeratic rocks has considerable local relief, with meter-scale scours and a valley fill >100 m thick. The scours have northeast-southwest orientations, which parallel both the paleocurrents in the underlying Parahio Formation as well as published paleocurrent readings from the coarse red beds of the overlying Ordovician strata. The Cambrian–Ordovician unconformity is of regional extent, and our recent biostratigraphic database indicates that the minimum hiatus associated with the unconformity in Spiti is ∼15 m.y. Our sedimentological analysis and associated paleocurrent data from the Parahio Formation, along with additional data from units both above and below the unconformity, indicate that published models portraying foreland basin development at this time with southward-directed thrusting are problematic. An alternate possibility—that uplift took place south of the Tethyan Himalaya—is also problematic, because no published stratigraphic or structural evidence exists for such an uplift to the south for either the Greater or the Lesser Himalaya lithotectonic zones. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.