Sediment geochemistry of the Lower Jurassic Gordondale Member, northeastern British Columbia

Abstract

Research Article| December 01, 2006 Sediment geochemistry of the Lower Jurassic Gordondale Member, northeastern British Columbia Daniel J.K. Ross; Daniel J.K. Ross Department of Geological Sciences, University of British Columbia, 6339 Stores Road, Vancouver, BC V6T 1Z4 Search for other works by this author on: GSW Google Scholar R. Marc Bustin R. Marc Bustin Department of Geological Sciences, University of British Columbia, 6339 Stores Road, Vancouver, BC V6T 1Z4 Search for other works by this author on: GSW Google Scholar Author and Article Information Daniel J.K. Ross Department of Geological Sciences, University of British Columbia, 6339 Stores Road, Vancouver, BC V6T 1Z4 R. Marc Bustin Department of Geological Sciences, University of British Columbia, 6339 Stores Road, Vancouver, BC V6T 1Z4 Publisher: Canadian Society of Petroleum Geologists Received: 04 Jan 2006 Accepted: 20 Sep 2006 First Online: 09 Mar 2017 Online ISSN: 2368-0261 Print ISSN: 0007-4802 © The Society of Canadian Petroleum Geologists Bulletin of Canadian Petroleum Geology (2006) 54 (4): 337–365. https://doi.org/10.2113/gscpgbull.54.4.337 Article history Received: 04 Jan 2006 Accepted: 20 Sep 2006 First Online: 09 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 Daniel J.K. Ross, R. Marc Bustin; Sediment geochemistry of the Lower Jurassic Gordondale Member, northeastern British Columbia. Bulletin of Canadian Petroleum Geology 2006;; 54 (4): 337–365. doi: https://doi.org/10.2113/gscpgbull.54.4.337 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 SocietyBulletin of Canadian Petroleum Geology Search Advanced Search Abstract Paleoenvironments during the Jurassic Gordondale Member sedimentation have been investigated using detailed geochemistry. Four offshore marine litho-stratigraphic units occur within the Gordondale in the Peace River Embayment area of northeastern British Columbia (NE B.C.). The basal mudstone conglomerate/breccia unit (unit A) represents the initiation of a transgression across the basin. The overlying phosphatic marlstone (unit B) was deposited during a time of high organic productivity, characterized by enrichments in the productivity proxying element P2O5 and total organic carbon (TOC) contents averaging 5.5 weight percent. Under these conditions, bio-productivity elements (V, Cr, Cu, Ni, Zn) were effectively incorporated with the organic fraction (matrix bituminite). The co-occurrence of the marine phosphate francolite and pyrite suggests the dysoxic-anoxic redox boundary oscillated vertically in the sediment with time.A shift in geochemistry occurs at the onset of the overlying unit C deposition. Unit C sediments are highly siliceous, low in detrital proxying elements (e.g. Al2O3, K2O, Fe2O3, TiO2, Rb, Co, Zr, Nb) and characterized by high TOC (6–21 weight percent). Excess SiO2 (i.e. silica which cannot be accounted for by the aluminosilicate phase) accounts for up to 94% of the SiO2 in the organic-rich sections, suggesting a biosiliceous source. A productive water column is also inferred by relatively high Ba concentrations. The low concentrations of all other major oxides and trace metals in unit C reflect silica dilution in the depositional basin. Carbon-S-Fe plots show a sulfidic bottom-water environment persisted for much of unit C deposition where S was concentrated into the organic fraction (alginite and matrix bituminite) due to the lack of Fe available for pyrite formation.Unit D represents two different stages of sedimentation. The contact between units C and D is marked by a phosphatic rich-marlstone, depleted in all major and trace elements except CaO, P2O5 and Mn. The enrichment of Mn in the carbonate suggests dissolved oxygen was present in bottom waters. Thereafter, unit D is dominated compositionally by detrital proxying elements (clays and associated elements such as Ti, K and Fe) reflecting an increase of terrigenous input. However, despite the sediment-dilution by aluminosilicate phases, TOC contents are comparable to unit B, averaging 5.6 weight percent. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.