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GEOREF RECORD

Paleoenvironmental and biotic changes across the Cretaceous-Tertiary boundary in the Oman Mountains

Jack Roger, Chantal Bourdillon, Philippe Razin, Laurence Le Callonnec, Maurice Renard, Marie-Pierre Aubry, Jean Philip, Jean-Pierre Platel, Robert Wyns and Monique Bonnemaison
Modifications des paleoenvironnements et des associations biologiques autour de la limite Cretace-Tertiaire dans les montagnes d'Oman
Bulletin de la Societe Geologique de France (March 1998) 169 (2): 255-270

Abstract

Two new sites, revealing a record of the events at the K/T boundary, have been recently discovered in the Oman Mountains at the eastern end of the Arabian plate. In the Buraymi Basin, located at the northwestern flank of the chain, the K/T boundary is intersected by a basinal facies succession, whilst in the Sur area, the transition is illustrated within a confined carbonate platform sequence. This period exhibits important palaeoenvironmental and biotic changes which originated from the conjunction of multiple factors. These came together over differing intervals of time, i.e., long period of time, short time scale and instantaneous event. At the scale of the long period of time (4 Ma) stretching from late Maastrichtian to the Danian (Plc), the Oman Mountains recorded profound modifications in terms of their palaeogeographic context, undoubtedly linked to plate reorganisation. This was initially shown by the emersion of the rudist platforms and the flooding of the margins in the late, but not terminal, Maastrichtian. This first tectonic event introduced an hemipelagic and a turbiditic sedimentation. As a consequence, this episode created, at the southern limb of the chain, the confined Murka sub-basin characterised by a carbonate platform sedimentation. Because the transition terminal Maastrichtian-earliest Danian correspond to a period of tectonic quiescence, the sedimentation persisted through the K/T boundary without any notable modification. A second tectonic episode in the Danian Plb/Plc interval, accentuated the flooding of the plate margins where basin deposits were accumulating. The renewal of planktic foraminifera took place in stages suggesting a gradation of palaeoecological conditions spread over a short time scale (1 to 2 Ma). This gradation is marked by the succession of three waves of extinction which took place from the late Maastrichtian to the K/T boundary. Diversity of the benthic foraminifera then increased progressively from subzone Plb onwards, showing the re-establishment of the ecosystem in Plc. The iridium anomaly detected at the K/T boundary at both sites would tend to reinforce the hypothesis of a meteorite impact, the effects of which would have added to these events that unfolded over a longer time scale.


ISSN: 0037-9409
EISSN: 1777-5817
Coden: #02538
Serial Title: Bulletin de la Societe Geologique de France
Serial Volume: 169
Serial Issue: 2
Title: Modifications des paleoenvironnements et des associations biologiques autour de la limite Cretace-Tertiaire dans les montagnes d'Oman
Translated Title: Paleoenvironmental and biotic changes across the Cretaceous-Tertiary boundary in the Oman Mountains
Affiliation: Bureau de Recherches Geologiques et Minieres (BRGM), Service Geologique National, Orleans, France
Pages: 255-270
Published: 199803
Text Language: French
Summary Language: English
Publisher: Societe Geologique de France, Paris, France
References: 40
Accession Number: 1999-013842
Categories: Stratigraphy
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. block diags., sects., 10 tables, geol. sketch maps
Secondary Affiliation: Universite Pierre et Marie Curie, FRA, FranceUniversite de Montpellier II, FRA, FranceUniversite de Provence-St-Charles, FRA, FranceCalle SIROCO 10-34, Madrid, ESP, Spain
Country of Publication: France
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 199905
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