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Anhydrite-bearing andesite and dacite as a source for sulfur in magmatic-hydrothermal mineral deposits

Isabelle Chambefort, John H. Dilles and Adam J. R. Kent
Anhydrite-bearing andesite and dacite as a source for sulfur in magmatic-hydrothermal mineral deposits
Geology (Boulder) (September 2008) 36 (9): 719-722

Abstract

Magmatic anhydrite from andesites and dacites occurs as inclusions in high- and low-aluminum amphibole and pyroxene and indicates that sulfate-saturated magmas spanned a period of six million years at Yanacocha, Peru. Magmatic anhydrite from Yanacocha and other sites is characterized by light rare earth element-enriched patterns and elevated strontium contents distinct from magmatic-hydrothermal anhydrite. Petrologic arguments suggest that the hydrous and oxidized Yanacocha magmas contained more than approximately 1000 ppm sulfur both dissolved in the melt and as a separate sulfate phase, which is sufficient to provide all the sulfur for the genetically related giant sulfur-rich Yanacocha epithermal gold deposits. High-aluminum amphiboles contain unusual anhydrite with wormy and amoeboidal textures, which are tentatively interpreted to represent trapping of an immiscible CaSO (sub 4) -water melt together with sulfur-rich apatite at a temperature of approximately 950 degrees C and a water pressure >3 kbar. Such unusually sulfate-rich magmas may be required to produce sulfur-rich magmatic-hydrothermal mineral deposits.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 36
Serial Issue: 9
Title: Anhydrite-bearing andesite and dacite as a source for sulfur in magmatic-hydrothermal mineral deposits
Affiliation: Oregon State University, Department of Geosciences, Corvallis, OR, United States
Pages: 719-722
Published: 200809
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 22
Accession Number: 2008-116941
Categories: Economic geology, geology of ore depositsIgneous and metamorphic petrology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: With GSA Data Repository Item 2008181
Illustration Description: illus. incl. sect.
S07°00'00" - S07°00'00", W78°19'60" - W78°19'60"
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: 200844
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