Diagenetic formation of greigite and pyrrhotite in gas hydrate marine sedimentary systems

Online Access: Get full text
doi: 10.1016/j.epsl.2007.06.032
Author(s): Larrasoaña, Juan C.; Roberts, Andrew P.; Musgrave, Robert J.; Gràcia, Eulàlia; Piñero, Elena; Vega, Marta; Martínez-Ruiz, Francisca
Author Affiliation(s): Primary:
CSIC, Institut de Ciències de la Terra Jaume Almera, Barcelona, Spain
Other:
University of Southampton, United Kingdom
University of Newcastle, Australia
Volume Title: Earth and Planetary Science Letters
Source: Earth and Planetary Science Letters, 261(3-4), p.350-366. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0012-821X CODEN: EPSLA2
Note: In English. Supplemental information/data is available in the online version of this article. 54 refs.; illus., incl. sects.
Summary: Mineral magnetic results and electron microscope observations from gas hydrate-bearing marine sediments cored at southern Hydrate Ridge during Ocean Drilling Program Leg 204 (Sites 1244 to 1252, Cascadia Margin, offshore Oregon) demonstrate that authigenic greigite and pyrrhotite formed as a byproduct of microbially-mediated diagenetic reactions in the sulphate, the anaerobic oxidation of methane (AOM), and the methanic/gas hydrate zones. Geochemical conditions favourable for formation and preservation of greigite and pyrrhotite appear to be a limited source of sulphide, whether it derives from microbially-driven sulphate reduction in the sulphate zone, in the AOM zone or in deep sediments undergoing AOM, so that pyritization reactions are not driven to completion. Our results indicate that rock magnetic identification of greigite and pyrrhotite should be useful for detecting ancient gas hydrate systems in the marine sedimentary record, because it can enable rapid screening of ancient sediments for potential horizons where methane and disseminated gas hydrates might have occurred. Formation of authigenic greigite and pyrrhotite at different depths within the gas hydrate stability zone also implies that the magnetization of the host sediments will have been acquired at variable times, which is likely to compromise paleomagnetic results from greigite- and pyrrhotite-bearing marine sediments. Abstract Copyright (2007) Elsevier, B.V.
Year of Publication: 2007
Research Program: ODP Ocean Drilling Program
Key Words: 07 Marine Geology and Oceanography; Aliphatic hydrocarbons; Alkanes; Anaerobic environment; Authigenic minerals; Biogenic processes; Carbonates; Diagenesis; East Pacific; Gas hydrates; Greigite; Hydrate Ridge; Hydrocarbons; Hysteresis; Isothermal remanent magnetization; Leg 204; Magnetization; Marine environment; Marine sediments; Metasomatism; Methane; North Pacific; Northeast Pacific; ODP Site 1244; ODP Site 1245; ODP Site 1246; ODP Site 1247; ODP Site 1248; ODP Site 1249; ODP Site 1250; ODP Site 1251; ODP Site 1252; Ocean Drilling Program; Organic compounds; Pacific Ocean; Pyritization; Pyrrhotite; Remanent magnetization; Sediments; Siderite; Sulfates; Sulfides
Coordinates: N443400 N443500 W1250400 W1250900
Record ID: 2008013777
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands