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Tephrochronology and geochemistry of Eocene and Oligocene volcanic ashes of east and central Texas

2014; Geological Society of America; Volume: 127; Issue: 5-6 Linguagem: Inglês

10.1130/b31146.1

1943-2674

Mindi L. Heintz, Thomas E. Yancey, Brent V. Miller, Matthew T. Heizler,

Geology and Paleoclimatology Research

Research Article| May 01, 2015 Tephrochronology and geochemistry of Eocene and Oligocene volcanic ashes of east and central Texas Mindi L. Heintz; Mindi L. Heintz § 1Geology and Geophysics Department, Texas A&M University, College Station, Texas 77843, USA †Current address: 31906 Oak Crossing, Magnolia, Texas 77355, USA. §E-mails: miheintz@neo.tamu.edu, tyancey@geos.tamu.edu, bvmiller@geos.tamu.edu, matt@nmt.edu. Search for other works by this author on: GSW Google Scholar Thomas E. Yancey; Thomas E. Yancey § 1Geology and Geophysics Department, Texas A&M University, College Station, Texas 77843, USA §E-mails: miheintz@neo.tamu.edu, tyancey@geos.tamu.edu, bvmiller@geos.tamu.edu, matt@nmt.edu. Search for other works by this author on: GSW Google Scholar Brent V. Miller; Brent V. Miller § 1Geology and Geophysics Department, Texas A&M University, College Station, Texas 77843, USA §E-mails: miheintz@neo.tamu.edu, tyancey@geos.tamu.edu, bvmiller@geos.tamu.edu, matt@nmt.edu. Search for other works by this author on: GSW Google Scholar Matthew T. Heizler Matthew T. Heizler § 2New Mexico Bureau of Geology and Mineral Resources, Socorro, New Mexico 87801, USA §E-mails: miheintz@neo.tamu.edu, tyancey@geos.tamu.edu, bvmiller@geos.tamu.edu, matt@nmt.edu. Search for other works by this author on: GSW Google Scholar GSA Bulletin (2015) 127 (5-6): 770–780. https://doi.org/10.1130/B31146.1 Article history received: 02 Jun 2014 rev-recd: 15 Oct 2014 accepted: 04 Nov 2014 first online: 08 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Mindi L. Heintz, Thomas E. Yancey, Brent V. Miller, Matthew T. Heizler; Tephrochronology and geochemistry of Eocene and Oligocene volcanic ashes of east and central Texas. GSA Bulletin 2015;; 127 (5-6): 770–780. doi: https://doi.org/10.1130/B31146.1 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 single-crystal sanidine 40Ar/39Ar dates of 12 middle Eocene to Oligocene rhyolitic volcanic ash beds of the Texas coastal plains range from 30.64 ± 0.03 Ma (lower Catahoula Formation) to 41.841 ± 0.016 Ma (lower Crockett Formation). These dates are from Texas coastal plains strata in the Crockett marine transgression and the Yegua and Jackson depositional wedges. Radiometric dating of sanidine and electron microprobe analysis of volcanic apatite phenocrysts validate previous regional correlation of the Upper Alabama Ferry volcanic ash from Brazos County to Houston County, Texas, and provide support for correlation of this bed with the St. Johns bentonite deposit in Louisiana. Middle Eocene ash beds are distinguished by differences in apatite phenocryst composition. The wide distribution of the thick Alabama Ferry volcanic ashes points to an early age (41.841 ± 0.016 Ma) for the start of major explosive rhyolitic volcanism in western North America. Volcanic ash bed samples have subalkaline rhyolite composition with geochemical characteristics consistent with derivation from volcanic arc rocks. Trace-element data show a temporal change in volcanic ashes: Middle Eocene ashes are depleted in heavy rare earth elements compared to late Eocene and Oligocene units. This change in ash composition coincides with the time of transition from subduction compression to arc-rifting on the western margin of Mexico, and compositional data are consistent with the Sierra Madre Occidental being the source for the volcanic ash. Volcanic units of the eastern portion of the Trans-Pecos of Texas and Mogollon-Datil area of New Mexico overlap temporally, but geochemical characteristics and K/Ca ratios in sanidine indicate they are geochemically unlikely to be sources for the Texas coastal plains middle Eocene to Oligocene volcanic ash beds. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.