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Elevated mantle temperature beneath East Africa

Tyrone O. Rooney, Claude Herzberg and Ian D. Bastow
Elevated mantle temperature beneath East Africa
Geology (Boulder) (November 2011) 40 (1): 27-30

Abstract

The causes of magmatism at magmatic rifted margins and large igneous provinces (LIPs) are uncertain because the condition of the mantle that underlay them during formation can no longer be directly observed. Therefore, whether the mantle was characterized by elevated potential temperatures (T (sub P) ), small-scale convection, or anomalously fertile composition is debated. East Africa is an ideal area in which to address this problem because it contains both the young African-Arabian LIP and the tectonically and magmatically active East African Rift system. Here we present mantle T (sub P) estimates for 53 primitive magmas from throughout the region to reveal that thermal anomalies currently peak in Djibouti (140 degrees C above ambient upper mantle). Slightly warmer conditions accompanied the Oligocene African-Arabian LIP, when the T (sub P) anomaly was 170 degrees C. These values are toward the low end of the global temperature range of LIPs, despite the markedly slow seismic velocity mantle that underlies the region. Mantle seismic velocity anomalies in East Africa cannot, therefore, as is often assumed, be attributed simply to elevated mantle temperatures. We conclude that CO (sub 2) -assisted melt production in the African superplume contributes to the markedly slow seismic velocities below East Africa.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 40
Serial Issue: 1
Title: Elevated mantle temperature beneath East Africa
Affiliation: Michigan State University, Department of Geological Sciences, East Lansing, MI, United States
Pages: 27-30
Published: 20111114
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 42
Accession Number: 2012-016223
Categories: Solid-earth geophysics
Document Type: Serial
Bibliographic Level: Analytic
Annotation: With GSA Data Repository Item 2012012
Illustration Description: illus. incl. 1 table, sketch maps
S27°10'00" - N22°30'00", E22°00'00" - E51°30'00"
Secondary Affiliation: Rutgers University, USA, United StatesUniversity of Bristol, GBR, United Kingdom
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: 201209
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