ebooks logo journals logo reference works logo abstract databases logo
bullet  SIGN IN Register | Why Register? | Got a Voucher? alerts   marked lists   shopping cart 
Session timed out - new session started. You may need to sign in again. [ hide message ]

informaworld

HOME   |   SEARCH   |   BROWSE
    Issues List       Latest Issue       Forthcoming Articles       Volume 56 Issue 6       Subscribe       Article       References       Related articles      
<< firstfirst   < prevprev   Table of contentstoc   next >next   last >>last
Publisher Logo Publication Cover
Search within this journal

Anatomy of an anachronistic carbonate platform: Lower Triassic carbonates of the southwestern United States 

Author: A. D. Woods a
Affiliation:   a Department of Geological Sciences, California State University, CA, USA
DOI: 10.1080/08120090903002649
Publication Frequency: 8 issues per year
Published in: journal Australian Journal of Earth Sciences, Volume 56, Issue 6 August 2009 , pages 825 - 839
Formats available: HTML (English) : PDF (English)
Languages: English; #27721#35821
Previously published as: Journal of the Geological Society of Australia (0016-7614) until 1983
Article Requests: Order Reprints : Request Permissions


Abstract

Examination of Lower Triassic carbonate rocks from around the world has revealed the resurgence of atypical carbonates that were last common during the Proterozoic ('anachronistic facies'). Anachronistic facies are attributed to a combination of post-extinction paleoecologic factors and widespread, harsh environmental conditions, particularly the presence of anoxic, alkaline waters in the global ocean. The marine rocks of the Moenkopi Formation (Virgin Limestone) of southern Nevada and laterally equivalent deep-water limestones of the Union Wash Formation of east-central California provide a means to reconstruct depositional environments across a Lower Triassic carbonate ramp and place the atypical facies and fabrics that occur within those rocks into a larger 'Anachronistic Platform Model.' Examination of shallow subtidal and intertidal facies reveal widespread ooid shoals in both the Union Wash Formation and Virgin Limestone, as well as the presence of small, fringing stromatolite bioherms in shallow subtidal environments of the Union Wash Formation. Inner to middle ramp environments of the Virgin Limestone contain aggregates of cabbage-head stromatolites that formed 1-2 m-high patch-reef bioherms, in addition to flat-pebble conglomerates, mud-chip facies and wrinkle structures. Deep-water facies from the Union Wash Formation contain synsedimentary calcium carbonate precipitates that form laterally extensive crusts in basinal environments, or interlocking mosaics of hemispheres and fans in outer ramp to slope environments. The results of this study reveal that carbonate sedimentation during the Early Triassic was controlled by a combination of biotic factors, environmental stresses, unusual oceanic chemistry and normal carbonate sedimentary processes that resulted in the development of carbonate platforms that had affinities to both Phanerozoic and Proterozoic depositional systems.
Keywords: anachronistic facies; biotic recovery; California; carbonates; microbialites; Nevada; Triassic
view references (82)
Bookmark with:
  • CiteULike
  • Del.icio.us
  • BibSonomy
  • Connotea
  • More bookmarks
Privacy Policy | Terms & Conditions | Accessibility | RSS
FAQs in: English . Français . Español . 中文(简体和繁體)
© 2009 Informa plc