Pliocene-Quaternary volcanism and faulting at the intersection of the Gulf of California and the Mexican Volcanic Belt

Research Article| June 01, 1995 Pliocene-Quaternary volcanism and faulting at the intersection of the Gulf of California and the Mexican Volcanic Belt Kevin Righter; Kevin Righter 1Department 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 1Department of Geology and Geophysics, University of California, Berkeley, California 94720 Search for other works by this author on: GSW Google Scholar Tim A. Becker; Tim A. Becker 2Berkeley Geochronology Center, 2455 Ridge Road, Berkeley, California 94709 Search for other works by this author on: GSW Google Scholar Paul R. Renne Paul R. Renne 1Department of Geology and Geophysics, University of California, Berkeley, California 94720 Search for other works by this author on: GSW Google Scholar Author and Article Information Kevin Righter 1Department of Geology and Geophysics, University of California, Berkeley, California 94720 Ian S. E. Carmichael 1Department of Geology and Geophysics, University of California, Berkeley, California 94720 Tim A. Becker 2Berkeley Geochronology Center, 2455 Ridge Road, Berkeley, California 94709 Paul R. Renne 1Department of Geology and Geophysics, University of California, Berkeley, California 94720 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1995) 107 (6): 612–626. https://doi.org/10.1130/0016-7606(1995)107<0612:PQVAFA>2.3.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Kevin Righter, Ian S. E. Carmichael, Tim A. Becker, Paul R. Renne; Pliocene-Quaternary volcanism and faulting at the intersection of the Gulf of California and the Mexican Volcanic Belt. GSA Bulletin 1995;; 107 (6): 612–626. doi: https://doi.org/10.1130/0016-7606(1995)107<0612:PQVAFA>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 The junction of the western Mexican Volcanic Belt and the Gulf of California represents a superposition of subduction and continental rifting tectonic regimes in the late Cenozoic. Subduction of the oceanic Rivera plate has caused late Cenozoic uplift of western Mexico, forming the Jalisco Block. This paper addresses three questions: Where is the northern boundary of the Jalisco Block; how is the continental fracture system related to that offshore; and what is the spatial distribution and composition of subduction-related lavas?40Ar/39Ar dates on Cretaceous to Paleogene silicic ash flows show that the northern boundary of the Jalisco Block may be defined by the abrupt change in basement age from Cretaceous to Miocene. 40Ar/39Ar and K-Ar dates on faulted lavas from the Nayarit region indicate that extension at the edge of the Jalisco Block has occurred since ca. 4.2 Ma. The least principal stress (σ3 direction associated with these faults has had two different orientations from 4.2 Ma to the present: Several Pliocene to Holocene (4.20, 1.05, and 0.65 Ma) lava flows, and aligned cinder cones have a N45°W associated least principal stress direction, whereas three Pliocene (3.36, 3.38, and 3.11 Ma) lava flows are cut by faults indicating a north to north-northeast least principal stress direction. The two different stress directions may arise either from structural features in the basement of the arc or from changes in offshore plate boundaries (e.g., 2.5 Ma when the Rivera and Mathematicians plates were locked together).Whole-rock major and trace element analyses of lavas from the coastal Nayarit region reveal three different lava types: an alkali basalt series, basaltic andesite, and andesite. The alkali basalts show FeO and TiO2 enrichment and have low Ba/Zr and Ba/La ratios, consistent with derivation from an oceanic-island-type mantle. The basaltic andesites and andesites are both alkaline and calc-alkaline, contain hydrous phenocrysts, and have high Sr/Zr and La/Nb ratios, consistent with a subduction-related source. Among these lavas there is a correlation between Sr/Zr, oxygen fugacity, and H2O contents, suggesting that an oxidized, hydrous fluid is involved in the genesis of the subduction-related lavas. The distribution of subduction-related volcanic centers in the coastal Nayarit region, and areas southeast within the Jalisco Block, defines front that parallels the Middle America Trench and is consistent with a 45° dip on the subducted Rivera plate. 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.