Structural and lithological controls on large Quaternary rock avalanches (sturzstroms) in arid northwestern Argentina

Abstract

Research Article| June 01, 1999 Structural and lithological controls on large Quaternary rock avalanches (sturzstroms) in arid northwestern Argentina Reginald L. Hermanns; Reginald L. Hermanns 1Institut für Geowissenschaften, Universität Potsdam, Postfach 601553, D-14415 Potsdam, Germany Search for other works by this author on: GSW Google Scholar Manfred R. Strecker Manfred R. Strecker 1Institut für Geowissenschaften, Universität Potsdam, Postfach 601553, D-14415 Potsdam, Germany Search for other works by this author on: GSW Google Scholar GSA Bulletin (1999) 111 (6): 934–948. https://doi.org/10.1130/0016-7606(1999)111<0934:SALCOL>2.3.CO;2 Article history first online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Reginald L. Hermanns, Manfred R. Strecker; Structural and lithological controls on large Quaternary rock avalanches (sturzstroms) in arid northwestern Argentina. GSA Bulletin 1999;; 111 (6): 934–948. doi: https://doi.org/10.1130/0016-7606(1999)111<0934:SALCOL>2.3.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 Landsat thematic mapper (TM) analysis, aerial photograph interpretation, and field studies of the semiarid Puna Plateau, adjacent Eastern Cordillera, and Sierras Pampeanas of Argentina (lat 24°–28°S) have revealed the existence of at least 55 rock-avalanche deposits with volumes larger than 106 m3 that formed by the collapse of entire mountain fronts. The spatial distribution of landslide deposits is not random, but it clusters along mountain fronts bounded by active faults. Inspection in the field reveals five principal controls on the distribution of these events. The source area of the rock avalanches has two topographic constraints: (1) vertical relief contrasts between the breakaway zone and the mountain front must exceed a threshold of 400 m, and (2) the slope inclinations must be steeper than 20°. Rock avalanches are restricted to three types of lithology: granites, low-grade metamorphic rocks, and coarse clastic sediments. Structural controls are very important. Rock avalanches are controlled by planar structures such as bedding planes, exfoliation joints, minor faults, and cleavage that all dip toward the valley. In addition, major slide clusters occur along mountain fronts that underwent Quaternary reverse-fault reactivation of former transfer faults with strike-slip kinematics. The trigger mechanism for the majority of these landslides is interpreted to be seismic, although the ages of some major slides are about 30 ka, and they may correspond to a more humid interval in southern South America. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.