East-west extension and Miocene environmental change in the southern Tibetan plateau: Thakkhola graben, central Nepal (2002)

Research Article| January 01, 2003 East-west extension and Miocene environmental change in the southern Tibetan plateau: Thakkhola graben, central Nepal Carmala N. Garzione; Carmala N. Garzione 1Department of Earth and Environmental Sciences, University of Rochester, Rochester, New York 14627, USA Search for other works by this author on: GSW Google Scholar Peter G. DeCelles; Peter G. DeCelles 2Department of Geosciences, University of Arizona, Tucson, Arizona 85721, USA Search for other works by this author on: GSW Google Scholar Damian G. Hodkinson; Damian G. Hodkinson 2Department of Geosciences, University of Arizona, Tucson, Arizona 85721, USA Search for other works by this author on: GSW Google Scholar Tank P. Ojha; Tank P. Ojha 2Department of Geosciences, University of Arizona, Tucson, Arizona 85721, USA Search for other works by this author on: GSW Google Scholar Bishal N. Upreti Bishal N. Upreti 3Department of Geology, Tribhuvan University, Tri-Chandra Campus, Ghantaghar, Kathmandu, Nepal Search for other works by this author on: GSW Google Scholar Author and Article Information Carmala N. Garzione 1Department of Earth and Environmental Sciences, University of Rochester, Rochester, New York 14627, USA Peter G. DeCelles 2Department of Geosciences, University of Arizona, Tucson, Arizona 85721, USA Damian G. Hodkinson 2Department of Geosciences, University of Arizona, Tucson, Arizona 85721, USA Tank P. Ojha 2Department of Geosciences, University of Arizona, Tucson, Arizona 85721, USA Bishal N. Upreti 3Department of Geology, Tribhuvan University, Tri-Chandra Campus, Ghantaghar, Kathmandu, Nepal Publisher: Geological Society of America Received: 13 Apr 2001 Revision Received: 29 Apr 2002 Accepted: 28 Jun 2002 First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (2003) 115 (1): 3–20. https://doi.org/10.1130/0016-7606(2003)115<0003:EWEAME>2.0.CO;2 Article history Received: 13 Apr 2001 Revision Received: 29 Apr 2002 Accepted: 28 Jun 2002 First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Carmala N. Garzione, Peter G. DeCelles, Damian G. Hodkinson, Tank P. Ojha, Bishal N. Upreti; East-west extension and Miocene environmental change in the southern Tibetan plateau: Thakkhola graben, central Nepal. GSA Bulletin 2003;; 115 (1): 3–20. doi: https://doi.org/10.1130/0016-7606(2003)115<0003:EWEAME>2.0.CO;2 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 East-west extensional basins are distributed across the southern half of the Tibetan plateau at an elevation of ∼4 km. These basins have generated much interest because of their potential implications for the regional tectonics and force distribution in the plateau. This study documents the sedimentology of the Miocene–Pliocene Thakkhola graben fill in order to reconstruct basin evolution and paleoenvironment. Analysis of depositional systems, paleodrainage patterns, and conglomerate clast provenance of the >1-km-thick graben fill sets limits on the timing of activity of the basin-bounding faults and the development of southward axial drainage in the basin. During the deposition of the oldest basin fill (Tetang Formation, ca. 11–9.6 Ma), probably in a restricted basin, minor motion occurred on the basin-bounding fault systems. An angular unconformity separates the Tetang and overlying Thakkhola Formations, where this contact can be observed in the southern part of the basin. Southward axial drainage was established by ca. 7 Ma with the onset of deposition of the Thakkhola Formation. Several episodes of damming of this drainage system are recorded by widespread lacustrine deposits in the southern part of the basin. Facies distribution and the progressive rotation of strata in the Thakkhola Formation indicate that the Dangardzong fault on the western edge of the basin was active at this time, and drainage ponding may have been related to displacement on normal faults associated with the South Tibetan detachment system to the south of Thakkhola graben.Contrasts between deposits of the Tetang and Thakkhola Formations provide evidence for environmental change in the basin. In the Tetang Formation, the abundance of lacustrine facies, the pollen record, and the absence of paleosol carbonate suggest that conditions were more humid than during subsequent deposition of the Thakkhola Formation. Environmental change in the Thakkhola graben coincided with environmental change observed in the Siwalik foreland basin sequence, Arabian Sea, and Bay of Bengal at ca. 8–7 Ma. Although this climate change event has been previously attributed to intensification of the Asian monsoon in response to uplift of the Tibetan plateau, paleoaltimetry data indicate that this region had already attained a high elevation by ca. 11 Ma. Thus, the Thakkhola graben stratigraphic record suggests that uplift of the southern Tibetan plateau and the onset of the Asian monsoon as inferred from paleoclimatic indicators were not directly related in a simple way. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.