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Mesozoic ash-flow caldera fragments in southeastern Arizona and their relation to porphyry copper deposits.

Geology

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and

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Abstract

Jurassic and Upper Cretaceous volcanic and associated granitic rocks in SE Arizona are remnants of large composite silicic volcanic fields, characterized by voluminous ash-flow tuffs and associated calderas. Presence of 10-15 large caldera fragments is inferred primarily from 1) ash-flow deposits over 1 km thick, having features of inter-caldera ponding; 2) 'exotic-block' breccia within a tuff matrix, interpreted as caldera-collapse megabreccia; and 3) local granitic intrusion along arcuate structural boundaries of the thick volcanics. Several major porphyry copper deposits are associated with late granitic intrusions within the calderas or along their margins. Such close spatial and temporal association casts doubt on models that associate porphyry copper deposits exclusively with intermediate composition strato-volcanoes. -L.C.H.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Mesozoic ash-flow caldera fragments in southeastern Arizona and their relation to porphyry copper deposits.
Series title:
Geology
Volume
13
Issue:
9
Year Published:
1985
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Geology
First page:
652
Last page:
656