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GEOREF RECORD

Ocean-ridge metalliferous and pelagic sediments of the Semail Nappe, Oman

Andrew J. Fleet and Alastair H. F. Robertson
Ocean-ridge metalliferous and pelagic sediments of the Semail Nappe, Oman (in Metallogenesis at oceanic spreading centres, D. S. Cronan (prefacer))
Journal of the Geological Society of London (July 1980) 137, Part 4: 403-422

Abstract

The lavas of the Semail ophiolitic nappe of Oman, which formed at and very near a late Cretaceous oceanic spreading axis, are intercalated with, and overlain by a range of metalliferous sediments including cupriferous sulphides, ferruginous ochres and ferro-manganiferous umbers. The lava sequence is divisible into lower and upper informal units. The 'lower' lavas contain small massive sulphides and ochres which either formed by sea-floor oxidation of sulphides or were directly precipitated. In one area the basal 'upper' lavas contain mounds of ferruginous oxide sediments associated with umbers. The mounds may have resulted from bacterial precipitation of sulphides and/or Fe-oxy-hydroxides. Localized umbers deposited from hydrothermal solutions occur throughout and immediately above the 'upper' lavas, including areas where sea-floor faulting produced thick accumulations of volcaniclastic breccias. The uppermost umbers are overlain by radiolarites and foraminiferal chalk. Non-calcareous radiolarites are restricted to successions above umbers in some hollows suggesting that dissolution of calcareous pelagic sediment by acid hydrothermal solutions occurred during their ponded accumulation. Most of the metalliferous deposits and pelagic sediments can be related to a spreading ocean ridge affected by sea-floor fault zones. Others are associated with extrusives which have island-arc affinities and built up as discrete volcanic centres on the sea-floor.


ISSN: 0016-7649
EISSN: 2041-479X
Coden: JGSLAS
Serial Title: Journal of the Geological Society of London
Serial Volume: 137, Part 4
Title: Ocean-ridge metalliferous and pelagic sediments of the Semail Nappe, Oman
Title: Metallogenesis at oceanic spreading centres
Author(s): Fleet, Andrew J.Robertson, Alastair H. F.
Author(s): Cronan, D. S.prefacer
Affiliation: Open Univ., Dep. Earth Sci., Milton Keynes, United Kingdom
Affiliation: Imp. Coll., Dep. Geol., London, United Kingdom
Pages: 403-422
Published: 198007
Text Language: English
Publisher: Geological Society of London, London, United Kingdom
References: 29
Accession Number: 1983-024142
Categories: Economic geology, geology of ore deposits
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table, block diag., sect., strat. cols., geol. sketch map
N17°00'00" - N27°00'00", E52°30'00" - E60°00'00"
Secondary Affiliation: Univ. Edinburgh, Grant Inst. Geol., GBR, United Kingdom
Country of Publication: United Kingdom
Secondary Affiliation: GeoRef, Copyright 2020, American Geosciences Institute.
Update Code: 1983
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