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Very long-term stability of passive margin escarpment constrained by (super 40) Ar/ (super 39) Ar dating of K-Mn oxides

Anicet Beauvais, Nicolas J. Bonnet, Dominique Chardon, Nicolas Arnaud and Mudlappa Jayananda
Very long-term stability of passive margin escarpment constrained by (super 40) Ar/ (super 39) Ar dating of K-Mn oxides
Geology (Boulder) (March 2016) 44 (4): 299-302

Abstract

The post-rift denudation history of high-elevation divergent continental margins is central to deciphering source-to-sink systems across such margins and to unraveling their topographic evolution. We performed (super 40) Ar- (super 39) Ar dating of supergene K-Mn oxides from supergene manganese ore deposits in order to constrain the age of in situ formed laterites on both the lowland and highland sides of the Western Ghats Escarpment of Peninsular India. Documentation of laterites as old as 53 Ma on the highland and 47 Ma at the foot of the escarpment shows that the escarpment stabilized before 47 Ma (possibly 60 Ma). The topographic setting of the dated weathering mantles also constrains denudation of the lowland and the highland since ca. 50 Ma to maximums of 5 m/m.y. and 15 m/m.y., respectively. Our results challenge denudation rates derived from apatite fission track thermochronology by documenting the topography and relief longevity of the southwest Indian margin and its hinterland. The results preclude large-magnitude uplift of Peninsular India after the Eocene, and more generally argue against late Neogene uplift and topographic rejuvenation of continental shields.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 44
Serial Issue: 4
Title: Very long-term stability of passive margin escarpment constrained by (super 40) Ar/ (super 39) Ar dating of K-Mn oxides
Affiliation: Aix-Marseille Universite, Centre Europeen de Recherche et d'Enseignement des Geosciences de l'Environnement, Aix-en-Provence, France
Pages: 299-302
Published: 20160307
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 28
Accession Number: 2016-033022
Categories: GeomorphologyGeochronology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: GSA Data Repository item 2016090
Illustration Description: illus. incl. sect., 1 table, sketch map
Secondary Affiliation: Institut de Recherche pour le Developpement, Geosciences Environnement Toulouse, FRA, FranceUniversite de Montpellier II, FRA, FranceUniversity of Hyderabad, IND, India
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201616
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