Secular change in the Precambrian silica cycle: Insights from chert petrology

Research Article| July 01, 2005 Secular change in the Precambrian silica cycle: Insights from chert petrology Robert G. Maliva; Robert G. Maliva 1Camp Dresser and McKee, Inc., 9311 College Parkway, Suite 1, Fort Myers, Florida 33919, USA Search for other works by this author on: GSW Google Scholar Andrew H. Knoll; Andrew H. Knoll 2Botanical Museum, Harvard University, 24 Oxford Street, Cambridge, Massachusetts 02138, USA Search for other works by this author on: GSW Google Scholar Bruce M. Simonson Bruce M. Simonson 3Department of Geology, Oberlin College, 52 West Lorain Street, Oberlin, Ohio 44074, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Robert G. Maliva 1Camp Dresser and McKee, Inc., 9311 College Parkway, Suite 1, Fort Myers, Florida 33919, USA Andrew H. Knoll 2Botanical Museum, Harvard University, 24 Oxford Street, Cambridge, Massachusetts 02138, USA Bruce M. Simonson 3Department of Geology, Oberlin College, 52 West Lorain Street, Oberlin, Ohio 44074, USA Publisher: Geological Society of America Received: 05 Jan 2004 Revision Received: 03 Sep 2004 Accepted: 03 Jan 2005 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (2005) 117 (7-8): 835–845. https://doi.org/10.1130/B25555.1 Article history Received: 05 Jan 2004 Revision Received: 03 Sep 2004 Accepted: 03 Jan 2005 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Robert G. Maliva, Andrew H. Knoll, Bruce M. Simonson; Secular change in the Precambrian silica cycle: Insights from chert petrology. GSA Bulletin 2005;; 117 (7-8): 835–845. doi: https://doi.org/10.1130/B25555.1 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 Chert deposits preserve a record of secular change in the oceanic silica cycle. The evolutionary radiation of silica-secreting organisms resulted in a transition from abiological silica deposition, characteristic of the Archean and Proterozoic eons, to the predominantly biologically controlled silica deposition of the Phanerozoic. Comparative petrography of Phanerozoic and Precambrian cherts indicates that an earlier change in chert deposition occurred toward the end of the Paleoproterozoic era (ca. 1.8 Ga). In Neoproterozoic and Mesoproterozoic strata, early diagenetic chertification is largely restricted to peritidal environments. These early diagenetic cherts typically occur as nodules or discontinuous beds within carbonate deposits that have similar depositional textures. The cherts formed primarily by carbonate replacement with subsidiary direct silica precipitation. Some of the Paleoproterozoic cherts associated with iron formations, however, are distinctly different from younger cherts and appear to have formed largely by direct silica precipitation at or just below the seabed. These primary cherts lack ghosts or inclusions of carbonate precursors, have fine-scale grain fracturing (possibly from syneresis), exhibit low grain-packing densities, and are not associated with unsilicified carbonate deposits of similar depositional composition. Cherts in some Paleoproterozoic iron formations (e.g., the Gunflint Formation, northwestern Lake Superior region) are composed of silica types similar to those in Phanerozoic sinters (e.g., the Devonian Rhynie and Windyfield cherts, Scotland). Such cherts may provide evidence that basinal, and perhaps global, oceanic silica concentrations were higher during the Paleoproterozoic era than at later times. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.