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Age of Etendeka flood volcanism and associated intrusions in southwestern Africa

Paul R. Renne, Jonathan M. Glen, Simon C. Milner and Andrew R. Duncan
Age of Etendeka flood volcanism and associated intrusions in southwestern Africa
Geology (Boulder) (July 1996) 24 (7): 659-662

Abstract

Detailed (super 40) Ar/ (super 39) Ar laser step-heating analyses of mineral separates from five volcanic units in Namibia and Angola and five intrusions in Namibia yield important geochronological data for the Etendeka igneous province. Ten plateau dates on plagioclase, hornblende, and biotite between 131.7 + or - 0.7 and 132.3 + or - 0.7 Ma were obtained, and a late syenite from the Messum intrusive complex yielded a slightly younger hornblende plateau date of 129.3 + or - 0.7 Ma. Magnetostratigraphy of the volcanic rocks in three sections up to 700 m thick, laterally spanning more than 100 km, suggests that the flows record only two geomagnetic polarity reversals. Precise temporal coincidence with the Parana flood volcanic province in South America indicates that Etendeka volcanism does not represent a significantly younger phase of magmatism that migrated from northwest to southeast over 10 m.y., as has recently been proposed. The duration of intrusive activity was at least 2 - 3 m.y. longer than recorded by volcanism, and its total duration awaits further constraints.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 24
Serial Issue: 7
Title: Age of Etendeka flood volcanism and associated intrusions in southwestern Africa
Affiliation: Berkeley Geochronology Center, Berkeley, CA, United States
Pages: 659-662
Published: 199607
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 25
Accession Number: 1996-054297
Categories: GeochronologyIgneous and metamorphic petrology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: With GSA Data Repository Item 9634
Illustration Description: illus. incl. geol. sketch map
S21°45'00" - S20°15'00", E13°40'00" - E14°40'00"
Secondary Affiliation: Geological Survey of Namibia, P.O. Box 2168, Windhoek, NAM, NamibiaUniversity of Cape Town, Department of Geological Sciences, Rondebosch 7700, ZAF, South Africa
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 199618
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