Pre–1 Ga (pre-Rodinian) ophiolites: Their tectonic and environmental implications

Abstract

Research Article| January 01, 2002 Pre–1 Ga (pre-Rodinian) ophiolites: Their tectonic and environmental implications Eldridge M. Moores Eldridge M. Moores 1Department of Geology, University of California, Davis, California 95616, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Eldridge M. Moores 1Department of Geology, University of California, Davis, California 95616, USA Publisher: Geological Society of America Received: 22 Sep 2000 Revision Received: 16 May 2001 Accepted: 21 Aug 2001 First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (2002) 114 (1): 80–95. https://doi.org/10.1130/0016-7606(2002)114<0080:PGPROT>2.0.CO;2 Article history Received: 22 Sep 2000 Revision Received: 16 May 2001 Accepted: 21 Aug 2001 First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Eldridge M. Moores; Pre–1 Ga (pre-Rodinian) ophiolites: Their tectonic and environmental implications. GSA Bulletin 2002;; 114 (1): 80–95. doi: https://doi.org/10.1130/0016-7606(2002)114<0080:PGPROT>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 A global survey of sutures predating formation of the supercontinent Rodinia, i.e., older than ca. 0.9–1.0 Ga, has yielded evidence for at least 35 described and possible ophiolite complexes. Results indicate that ophiolitic complexes older than 1.0 Ga mostly lack mantle tectonites below the magmatic rocks. Geochemically, these pre-Rodinian ophiolites display a mix of supra-subduction zone (SSZ), mid-oceanic-ridge, and oceanic- island compositions, with higher proportions of komatiite in complexes older than 1.6 Ga. Magmatic ages of identified and inferred complexes tend to cluster at times of 1.0–1.5 Ga, 1.8–2.3 Ga, ca. 2.5–2.7 Ga, and ca. 3.4 Ga. The data mostly support the hypothesis that magmatic oceanic crust was thicker prior to 1.0 Ga and thinned abruptly at 1.0 Ga. Mesozoic oceanic plateaus, e.g., the Caribbean, may provide an analogue to pre–1 Ga oceanic crust. A modified ophiolite columnar section to accommodate pre–1 Ga complexes includes a "1972 Penrose Conference–type" section in which the igneous rocks are overlain by a thick accumulation of interlayered sedimentary and volcanic rocks, as well as high-level intrusive complexes and plutons. Thinning of oceanic crust, the end of the anorthosite-anorogenic granite "event' at 1000 Ma, and discontinuous hotspot activity through time suggest discontinuous magmatic evolutionary processes in Earth history, similar to other planets. Differences in thickness and "subductability" of oceanic crust may provide clues to the Archean-Proterozoic tectonic transition. The stratigraphic and sea-level effects of the inferred 1 Ga thinning of oceanic crust include widespread continental emergence, development of seasons, and increased atmospheric oxygen leading to the Phanerozoic. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.