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The 89 Ma Tortugal komatiitic suite, Costa Rica; implications for a common geological origin of the Caribbean and eastern Pacific region from a mantle plume

Guillermo E. Alvarado, Percy Denyer and Christopher W. Sinton
The 89 Ma Tortugal komatiitic suite, Costa Rica; implications for a common geological origin of the Caribbean and eastern Pacific region from a mantle plume
Geology (Boulder) (May 1997) 25 (5): 439-442

Abstract

Komatiites are reported for the first time in the northern part of the Gulf of Nicoya, Costa Rica. These rocks, dated at 89.7+ or -1.4 Ma (Turonian) by (super 40) Ar/ (super 39) Ar methods, occur as a large, elongated (14 km long, 1.5 km wide) N60 degrees W striking body in the ophiolitic Nicoya Complex. These lavas have high MgO (26%-29%), Ni, and Cr, have high CaO/Al (sub 2) O (sub 3) (0.98-1.08) and moderate Al (sub 2) O (sub 3) /TiO (sub 2) (5.55-8.44) ratios, and are depleted in Al (sub 2) O (sub 3) (4%-5.5%), K (sub 2) O (0.02%-0.37%), and TiO (sub 2) (0.59%-0.9%). Although these lavas are cumulates, their geochemical composition indicates an origin from a primary komatiitic magma, with a melting temperature of 1700 degrees C at a depth of 150 km. Similarities in the petrology and age (88-90 Ma) of Gorgona, Curacao, and Nicoya-Tortugal mafic and ultramafic volcanic rocks suggest that these rocks had a common origin. These occurrences suggest a single hotspot center over a large area of the Caribbean and eastern Pacific Mesozoic region due to a major thermal anomaly in the mantle, such as a hot, rising, convective plume.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 25
Serial Issue: 5
Title: The 89 Ma Tortugal komatiitic suite, Costa Rica; implications for a common geological origin of the Caribbean and eastern Pacific region from a mantle plume
Affiliation: Instituto Costarricense de Electricidad, Departamento Ingenieria Geologica, San Jose, Costa Rica
Pages: 439-442
Published: 199705
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 37
Accession Number: 1997-038507
Categories: Geochemistry of rocks, soils, and sedimentsIgneous and metamorphic petrologyGeochronology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: IGCP Project No. 364
Illustration Description: illus. incl. sketch maps
N10°00'00" - N10°15'00", W85°00'00" - W85°00'00"
Secondary Affiliation: Universidad de Costa Rica, San Jose, CRI, Costa RicaUniversity of Rhode Island, Narragansett, RI, USA, United States
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: 199713
Program Name: IGCPInternational Geological Correlation Programme
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