Extensional deformation and paleomagnetism at the western margin of the Gulf extensional province, Puertecitos Volcanic Province, northeastern Baja California, Mexico

Abstract

Research Article| June 01, 2000 Extensional deformation and paleomagnetism at the western margin of the Gulf extensional province, Puertecitos Volcanic Province, northeastern Baja California, Mexico Elizabeth A. Nagy Elizabeth A. Nagy 1Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125, USA Search for other works by this author on: GSW Google Scholar GSA Bulletin (2000) 112 (6): 857–870. https://doi.org/10.1130/0016-7606(2000)112<857:EDAPAT>2.0.CO;2 Article history received: 22 Dec 1998 rev-recd: 26 Jul 1999 accepted: 30 Aug 1999 first online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Elizabeth A. Nagy; Extensional deformation and paleomagnetism at the western margin of the Gulf extensional province, Puertecitos Volcanic Province, northeastern Baja California, Mexico. GSA Bulletin 2000;; 112 (6): 857–870. doi: https://doi.org/10.1130/0016-7606(2000)112<857:EDAPAT>2.0.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 SocietyGSA Bulletin Search Advanced Search Abstract During the late Miocene east-northeast–directed extension in the Gulf of California extensional province, the western rift margin in northeastern Baja California, Mexico, was segmented at the northwest-striking Matomí accommodation zone. The accommodation zone passed through the northern Puertecitos Volcanic Province and separated pre–6 Ma extension to the north from the unextended region to the south. Pre–6 Ma northeast-side-down displacement is documented across the accommodation zone, which may have undergone dextral oblique-slip motion. The rift margin migrated westward during the latest Miocene or Pliocene, bypassing accommodation-zone structures and incorporating the Puertecitos Volcanic Province into the region of Gulf extensional province deformation. East-northeast– to east-directed extensional deformation is at least post–6 Ma in the northern Puertecitos Volcanic Province and deformation currently continues. Pliocene changes in the Gulf of California spreading center system may have triggered incorporation of the Puertecitos Volcanic Province into the Gulf extensional province as recently as 2–3 Ma. Paleomagnetic analyses of 6.3–6.6 Ma pyroclastic flow deposits show no consistent evidence for rotational deformation, although minor (∼10°–15°) clockwise rotation is possible given anomalous declination directions recorded at some sites. Comparisons with paleosecular variation models and the late Miocene paleopole for stable North America imply no statistically significant rotation relative to geomagnetic north, although minor (∼10°) clockwise rotation is permissible given uncertainties. Geologic relationships show that pre–6 Ma accommodation-zone structures identified in this study did not mark the southern boundary of later rotational deformation documented to the north. The boundary of Pliocene to Holocene rotations may be a broad, diffuse zone of extensional shear encompassing the northeastern Puertecitos Volcanic Province, which accommodated small rotations. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.