Deposition and diagenesis of silica in marine sediments

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doi: 10.1002/9781444304855.ch12
Author(s): Calvert, S. E.
Author Affiliation(s): Primary:
Inst. Oceanogr. Sci., Wormley, Godalming, Surrey, United Kingdom
Volume Title: Special Publication of the International Association of Sedimentologists
Source: Special Publication of the International Association of Sedimentologists, 1, p.273-299. Publisher: Blackwell, Oxford, International. ISSN: 0141-3600. ISBN: 978-1-444-30485-5 CODEN: SPISDS
Note: In English; illus.
Summary: Silica accumulates in observable quantities in marine sediments as planktonic debris (opal) in areas of high primary production and as ash and rock-alteration products in areas of extensive submarine volcanism. Diagenetic transformation of the silica leads to (a) solution and equilibration of opal and incipient precipitation of silicates in Recent sediments, and (b) the formation of chert in pre-Recent sediments. Rocks described as chert recovered during the Deep Sea Drilling Project are composed of cristobalite (= porcelanites) and quartz (=cherts sensu stricto). Cristobalitic porcelanites are also known in Mesozoic and Cenozoic siliceous formations on land. The cristobalite is highly disordered (=lussatite) and is formed by a solution step. The persistence of such a metastable phase in Mesozoic and Cenozoic rocks, although it does eventually recrystallize to quartz, is promoted by low ionic mobilities and/or low-energy conditions. The cristobalite precipitates from silica derived from biogenous opal and possibly also from volcanic debris. This conclusion is supported by the composition of the sediments associated with the porcelanites although the evidence is equivocal. More definitive criteria for distinguishing between these sources of silica are required. Abstract Copyright (1974), The International Association of Sedimentologists.
Year of Publication: 1974
Research Program: DSDP Deep Sea Drilling Project
Key Words: 07 Marine Geology and Oceanography; Atlantic Ocean; Biogenic; Cenozoic; Chemically precipitated rocks; Chert; Clastic rocks; Cristobalite; Deep Sea Drilling Project; Deposition; Diagenesis; Framework silicates; Geochemistry; Holocene; Marine; Mesozoic; Ocean floors; Opal; Pacific Ocean; Porcellanite; Precipitates; Quartz; Quaternary; Sedimentary rocks; Sedimentation; Sediments; Silica; Silica minerals; Silicates; Terrestrial; Volcanic ash
Record ID: 1975025999
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute.

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