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Low- and high-frequency sea-level changes control peritidal carbonate cycles, facies and dolomitization in the Rock of Gibraltar (Early Jurassic, Iberian Peninsula)

D. W. J. Bosence, J. L. Wood, E. P. F. Rose and H. Qing
Low- and high-frequency sea-level changes control peritidal carbonate cycles, facies and dolomitization in the Rock of Gibraltar (Early Jurassic, Iberian Peninsula)
Journal of the Geological Society of London (January 2000) 157, Part 1: 61-74

Abstract

The Rock of Gibraltar comprises two tectonically separated limbs of an isolated klippe of Liassic Gibraltar Limestone Formation. Both limbs have similar, c. 400 m thick sequences of inner carbonate platform facies arranged in high-frequency, metre-scale, shallowing-upward, peritidal cycles with emergent, caliche caps. Four cycle types are recognized on the basis of vertically repeated successions of different sedimentary structures, lithologies, facies and biota. When compared with other Liassic cycles from fault-bound platforms of the western Mediterranean region all are found to be of similar scale, facies and cycle type. Likely common origins are through Milankovitch band allocyclicity, or autocyclic tidal flat progradation superimposed on regional subsidence. Within the Gibraltar Limestone high-frequency cycles are superimposed on a low-frequency (third order?) cyclicity that is revealed, through the use of Fischer plots, to control the occurrence of facies, biota, high-frequency cycle types and dolomitization. Falling sea-level and lowstand phases, with reduced accommodation space, are typified by restricted, inner platform facies and cycles and by early reflux dolomitization. Transgressive and highstand phases, with more accommodation space, are characterized by the absence of early dolomites, the incoming of inner platform microfossils (i.e. foraminifera and calcareous algae) and by less restricted marine facies (i.e. oncoids, shelly rudstones, packstones and grainstones). Fischer plots have demonstrable value in the correlation and analysis of tectonically separated and geographically isolated cyclic sequences that lack prominent marker beds or stratigraphically useful biotas.


ISSN: 0016-7649
EISSN: 2041-479X
Coden: JGSLAS
Serial Title: Journal of the Geological Society of London
Serial Volume: 157, Part 1
Title: Low- and high-frequency sea-level changes control peritidal carbonate cycles, facies and dolomitization in the Rock of Gibraltar (Early Jurassic, Iberian Peninsula)
Affiliation: Royal Holloway University of London, Department of Geology, Egham, United Kingdom
Pages: 61-74
Published: 200001
Text Language: English
Publisher: Geological Society of London, London, United Kingdom
References: 56
Accession Number: 2000-028044
Categories: Stratigraphy
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sects., 2 tables, geol. sketch map
N36°08'60" - N36°08'60", W05°20'60" - W05°20'60"
Country of Publication: United Kingdom
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute. Reference includes data from The Geological Society, London, London, United Kingdom
Update Code: 200009
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