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Distribution of anomalously high K2O volcanic rocks in Arizona: metasomatism at the Picacho Peak detachment fault.

Geology

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Abstract

Metasomatized Tertiary lavas with anomalously high K2O and lower Na2O content are distributed within the NW-trending extensional terrain of SW Arizona. These rocks are common near core-complex-related detachment faults at Picacho Peak and the Harcuvar Mountains and in listric-faulted terrain at the Vulture Mountains. These rocks are also enriched in Zr but depleted in MgO. Fine-grained, euhedral orthoclase (adularia) is the dominant K-mineral; other secondary introduced minerals are quartz and calcite. Spatial association of metasomatism with the detachment faults suggests that detachment provided a conduit for hydrothermal fluids that altered the initial chemistry of the Tertiary volcanics and charged the upper plate rocks with mineralizing fluids that carried Zr and Ba, along with Au, Ag and Cu during detachment 17-18 m.y. ago.-L.C.H.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Distribution of anomalously high K2O volcanic rocks in Arizona: metasomatism at the Picacho Peak detachment fault.
Series title:
Geology
Volume
14
Issue:
4
Year Published:
1986
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Geology
First page:
339
Last page:
342
Number of Pages:
4