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Crustal extension and magmatic processes: COCORP profiles from Death Valley and the Rio Grande rift

1988; Geological Society of America; Volume: 100; Issue: 10 Linguagem: Inglês

10.1130/0016-7606(1988)100 2.3.co;2

1943-2674

B. de Voogd, Laura Serpa, L. D. Brown,

Seismic Waves and Analysis

Research Article| October 01, 1988 Crustal extension and magmatic processes: COCORP profiles from Death Valley and the Rio Grande rift BÉATRICE DE VOOGD; BÉATRICE DE VOOGD 1Institute for the Study of the Continents (INSTOC), and Department of Geological Sciences, Cornell University, Ithaca, New York 14853 Search for other works by this author on: GSW Google Scholar LAURA SERPA; LAURA SERPA 1Institute for the Study of the Continents (INSTOC), and Department of Geological Sciences, Cornell University, Ithaca, New York 14853 Search for other works by this author on: GSW Google Scholar LARRY BROWN LARRY BROWN 1Institute for the Study of the Continents (INSTOC), and Department of Geological Sciences, Cornell University, Ithaca, New York 14853 Search for other works by this author on: GSW Google Scholar Author and Article Information BÉATRICE DE VOOGD 1Institute for the Study of the Continents (INSTOC), and Department of Geological Sciences, Cornell University, Ithaca, New York 14853 LAURA SERPA 1Institute for the Study of the Continents (INSTOC), and Department of Geological Sciences, Cornell University, Ithaca, New York 14853 LARRY BROWN 1Institute for the Study of the Continents (INSTOC), and Department of Geological Sciences, Cornell University, Ithaca, New York 14853 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1988) 100 (10): 1550–1567. https://doi.org/10.1130/0016-7606(1988)100 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 MailTo Tools Icon Tools Get Permissions Search Site Citation BÉATRICE DE VOOGD, LAURA SERPA, LARRY BROWN; Crustal extension and magmatic processes: COCORP profiles from Death Valley and the Rio Grande rift. GSA Bulletin 1988;; 100 (10): 1550–1567. doi: https://doi.org/10.1130/0016-7606(1988)100 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 New crustal-scale information on the interaction between normal faulting and magmatic activity is provided by recent COCORP deep seismic reflection profiles in Death Valley, California, and by reprocessing of the COCORP data from the Socorro area of the Rio Grande rift, New Mexico. The most striking feature on the seismic sections from these areas is a prominent, subhorizontal series of reflectors at mid-crustal depth. Previous studies have suggested that thin tabular magma bodies lie within the mid-crustal reflective zones. In addition, because they are traced without apparent offset beneath faults both mapped at the surface and interpreted from the COCORP data, these mid-crustal horizons are here inferred to be detachments or zones of tectonic decoupling.Upper-crustal Cenozoic faults do not appear to penetrate deeper than 15 km in Death Valley and 13 km in the Rio Grande rift. In Death Valley, these faults are relatively planar, with moderate dips (20° to 35°), and appear to bound large basement rocks. One such zone of normal faults can be traced from the magma body inferred at 15 km depth beneath central Death Valley to the surface location of a 690,000-yr-old basaltic cinder cone. Listric and low- to moderate-angle normal faults are evident on the reprocessed New Mexico data and constitute the structural component of upper-crustal extension. In particular, a listric master fault traceable to depths as great as 13 km is inferred to underlie the Albuquerque basin. Unlike the Death Valley data, no faults are observed to merge with the Socorro magma body per se. Rather, subhorizontal to moderately west-dipping packages of reflections are imaged between the base of the faulted upper crust (13 km depth) and the mid-crustal magma body (about 20 km depth).The middle crust marks a major rheological boundary between the faulted upper crust and a ductile lower crust extending by penetrative flow and intrusion. Events seen in the middle and lower crust are generally subhorizontal, and prominent layering is observed. A band of reflections attributed to the crust-mantle boundary is evident on most seismic sections. The upper mantle appears seismically transparent. On some of the profiles, the events attributed to the base of the crust are the deepest in a series of strong and continuous reflections, at least one of which is a layer of magma. This association supports the suggestion that magmatic intrusions are a probable cause for the high reflectivity observed in the deep crust of many extensional terranes. 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.