Rock avalanches and the pace of late Quaternary development of river valleys in the Karakoram Himalaya

Abstract

Research Article| September 01, 2011 Rock avalanches and the pace of late Quaternary development of river valleys in the Karakoram Himalaya Kenneth. Hewitt; Kenneth. Hewitt † 1Department of Geography and Environmental Studies, Wilfrid Laurier University, 100 University Avenue, Waterloo, Ontario N2L 3C9, Canada †E-mail: [e-mail] Search for other works by this author on: GSW Google Scholar John. Gosse; John. Gosse 2Department of Earth Sciences, Dalhousie University, Edzell Castle Circle, Halifax, Nova Scotia B3H 4J1, Canada Search for other works by this author on: GSW Google Scholar John J. Clague John J. Clague 3Department of Earth Sciences, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada Search for other works by this author on: GSW Google Scholar Author and Article Information Kenneth. Hewitt † 1Department of Geography and Environmental Studies, Wilfrid Laurier University, 100 University Avenue, Waterloo, Ontario N2L 3C9, Canada John. Gosse 2Department of Earth Sciences, Dalhousie University, Edzell Castle Circle, Halifax, Nova Scotia B3H 4J1, Canada John J. Clague 3Department of Earth Sciences, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada †E-mail: [e-mail] Publisher: Geological Society of America Received: 19 May 2010 Revision Received: 24 Sep 2010 Accepted: 13 Oct 2010 First Online: 08 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 © 2011 Geological Society of America GSA Bulletin (2011) 123 (9-10): 1836–1850. https://doi.org/10.1130/B30341.1 Article history Received: 19 May 2010 Revision Received: 24 Sep 2010 Accepted: 13 Oct 2010 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 Kenneth. Hewitt, John. Gosse, John J. Clague; Rock avalanches and the pace of late Quaternary development of river valleys in the Karakoram Himalaya. GSA Bulletin 2011;; 123 (9-10): 1836–1850. doi: https://doi.org/10.1130/B30341.1 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 We discuss the implications of a set of terrestrial cosmogenic nuclide (TCN) ages on blocky, cross-valley deposits of large rock avalanches along upper Indus streams. The dated deposits are key to understanding late Quaternary events that play a major role in landscape evolution in the Karakoram Himalaya. The landslides occurred between 3 and 8 ka ago, challenging existing chronologies of events along Indus streams. The TCN ages may support a mid-Holocene climatic role in preparing slopes for failure, but the balance of evidence suggests that large earthquakes triggered the landslides. Each landslide dammed the Indus or a major tributary and controlled base level and sedimentation for millennia. They produced landforms long regarded as characteristic of the region, including extensive lacustrine deposits, flights of river terraces, epigenetic gorges, and sediment fans. Until the 1990s, most of the landslides were interpreted as moraines; related lacustrine and other sediments continue to be attributed to glacial damming, and stream terraces to tectonic processes. Generally they were seen to originate tens of thousands to hundreds of thousands of years earlier than the new ages require. Instead we argue that they record interactions among different geomorphic processes in landslide-fragmented valleys during the Holocene. Rather than being geomorphic markers of tectonic and climatic events, the landslides have buffered or redirected climatic and tectonic forcing. In such an active orogen, millennia-long episodes of zero net bedrock incision at each site are surprising. However, rates of sedimentation above landslide barriers and erosion controlled by their breaching are close to today's high measured rates for geomorphic activity. We propose that landslide-fragmented rivers may, in fact, characterize interglaciations and future patterns of upper Indus landscape evolution at time scales of 103 to 104 years. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.