Active rifting in southwestern Mexico: Manifestations of an incipient eastward spreading-ridge jump

Research Article| January 01, 1985 Active rifting in southwestern Mexico: Manifestations of an incipient eastward spreading-ridge jump James F. Luhr; James F. Luhr 1Department ol Geology, Franklin and Marshall College, Lancaster, Pennsylvania 17604 Search for other works by this author on: GSW Google Scholar Stephen A. Nelson; Stephen A. Nelson 2Department of Geology, Tulane University, New Orleans, Louisiana 70118 Search for other works by this author on: GSW Google Scholar James F. Allan; James F. Allan 3Department of Geology and Geophysics, University of California, Berkeley, California 94720 Search for other works by this author on: GSW Google Scholar Ian S. E. Carmichael Ian S. E. Carmichael 3Department of Geology and Geophysics, University of California, Berkeley, California 94720 Search for other works by this author on: GSW Google Scholar Geology (1985) 13 (1): 54–57. https://doi.org/10.1130/0091-7613(1985)132.0.CO;2 Article history first online: 01 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 James F. Luhr, Stephen A. Nelson, James F. Allan, Ian S. E. Carmichael; Active rifting in southwestern Mexico: Manifestations of an incipient eastward spreading-ridge jump. Geology 1985;; 13 (1): 54–57. doi: https://doi.org/10.1130/0091-7613(1985)132.0.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 A major, ongoing episode of continental rifting has formed a system of three intersecting grabens in the western Mexican volcanic belt. These structures may mark the initial stage of an eastward spreading-ridge jump beneath continental crust. Eastward ridge-segment jumps have been propagating northward along this part of the East Pacific Rise for the past 12 m.y., but this is the first plate-boundary reorganization event to involve continental crust since the separation of Baja California in the Miocene. Since Pliocene time, small volumes of unusual alkaline magmas have erupted in the graben areas in close association with the more abundant, subduction-related calc-alkaline magmas erupted from andesitic stratovolcanoes. The alkaline magmas are varieties found in zones of active rifting elsewhere in the world. 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.