Initial plate geometry, shortening variations, and evolution of the Bolivian orocline

Research Article| October 01, 2002 Initial plate geometry, shortening variations, and evolution of the Bolivian orocline Nadine McQuarrie Nadine McQuarrie 1Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Nadine McQuarrie 1Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125, USA Publisher: Geological Society of America Received: 14 Mar 2002 Revision Received: 21 Jun 2002 Accepted: 03 Jul 2002 First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (2002) 30 (10): 867–870. https://doi.org/10.1130/0091-7613(2002)030<0867:IPGSVA>2.0.CO;2 Article history Received: 14 Mar 2002 Revision Received: 21 Jun 2002 Accepted: 03 Jul 2002 First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Nadine McQuarrie; Initial plate geometry, shortening variations, and evolution of the Bolivian orocline. Geology 2002;; 30 (10): 867–870. doi: https://doi.org/10.1130/0091-7613(2002)030<0867:IPGSVA>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 SocietyGeology Search Advanced Search Abstract Comparisons of newly published cross sections across the Bolivian Andes with existing cross sections through Argentina emphasize significant along-strike changes in crustal shortening. A sharp decrease in the magnitude of crustal shortening from ∼530 km to ∼150 km (north to south) occurs at ∼23°S. A 20–40 m.y. difference in the ages at which deformation was initiated accompanies the abrupt decrease in the magnitude of shortening. Extending the western margin of South America to account for 530 km of shortening in the Bolivian Andes and 150 km of shortening in Argentina produces a central Andean salient that is perpendicular to the Nazca plate shortening direction from 60 to 26 Ma. During this same time interval, the Chilean coast south of 23°S was in an orientation sufficiently oblique to oceanic convergence to allow for predominantly strike-slip offset and backarc extension. Deformation within the Andean mountain chain may be a function of plate convergence where the oblique nature of convergence south of ∼23°S inhibited mountain building, whereas north of ∼23°S, normal convergence to a central Andean salient facilitated contractional deformation. The magnitude of deformation north of ∼23°S is a consequence of both plate-convergence direction, providing a longer period of contractional deformation (from ca. 70 Ma to the present), and a thick Phanerozoic sedimentary package that permitted large magnitudes of thin-skinned deformation. Significant along-strike changes in the shape of the South American margin—allowing for convergence to change from compression to extension along the strike of the orogen—may help explain the dramatic differences in timing, amount, and style of deformation in the Andes. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.