Evolution of waning, subduction-related magmatism, northern Sierra Madre Occidental, Mexico

Abstract

Research Article| November 01, 1990 Evolution of waning, subduction-related magmatism, northern Sierra Madre Occidental, Mexico D. A. WARK; D. A. WARK 1Department of Geological Sciences, The University of Texas at Austin, Austin, Texas 78713 Search for other works by this author on: GSW Google Scholar K. A. KEMPTER; K. A. KEMPTER 1Department of Geological Sciences, The University of Texas at Austin, Austin, Texas 78713 Search for other works by this author on: GSW Google Scholar F. W. MCDOWELL F. W. MCDOWELL 1Department of Geological Sciences, The University of Texas at Austin, Austin, Texas 78713 Search for other works by this author on: GSW Google Scholar Author and Article Information D. A. WARK 1Department of Geological Sciences, The University of Texas at Austin, Austin, Texas 78713 K. A. KEMPTER 1Department of Geological Sciences, The University of Texas at Austin, Austin, Texas 78713 F. W. MCDOWELL 1Department of Geological Sciences, The University of Texas at Austin, Austin, Texas 78713 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1990) 102 (11): 1555–1564. https://doi.org/10.1130/0016-7606(1990)102<1555:EOWSRM>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 D. A. WARK, K. A. KEMPTER, F. W. MCDOWELL; Evolution of waning, subduction-related magmatism, northern Sierra Madre Occidental, Mexico. GSA Bulletin 1990;; 102 (11): 1555–1564. doi: https://doi.org/10.1130/0016-7606(1990)102<1555:EOWSRM>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 stratigraphic record at the Tomochic volcanic center, Chihuahua, documents a change from andesitic to rhyolite-dominated volcanism, with late extrusion of mafic lavas, during the final ∼10 m.y. of subduction-related activity in the northern Sierra Madre Occidental. Andesitic volcanism, which started before 38 Ma and continued until ∼35 Ma, was followed by eruption of large-volume rhyolite ash flows from the Las Varas (34.1 Ma) and Tomochic (31.8-31.4 Ma) calderas. Basaltic andesite, the most mafic rock type in the area, was extruded near the end of calcalkalic volcanism at ∼30 Ma.The change in style of volcanism at the Tomochic volcanic center also occurred in other parts of the northern Sierra Madre Occidental and is interpreted to reflect the evolution of waning, subduction-related magmatism, as convergence between the North American and Farallon plates slowed before it eventually ceased. Slowed plate convergence resulted in a decreased flux of mafic melts from the mantle to the crust, leading, in turn, to the stagnation and coalescence of intermediate-composition magmas similar to those that fed early andesitic eruptions. Subsequent differentiation led to growth of zoned magma reservoirs from which the rhyolite ash flows were extruded. Slowed convergence was accompanied by the onset of crustal extension, which possibly aided the coalescence of andesitic magmas and which allowed the ascent and eruption of mafic melts near the end of silicic volcanic activity. Although minor differences exist, the history of mid-Tertiary magmatism and tectonism in the northern Sierra Madre Occidental was broadly similar to that in parts of the south-western United States. 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.