Mineralogy and geochemistry of Eocene intrusive rocks and their enclaves, El Paso area, Texas and New Mexico

C. G. Barnes, S. E. Ensenat, J. D. Hoover

Research output: Contribution to journalArticle

5 Scopus citations

Abstract

Trans-Pecos magmatism in the El Paso, Texas, area was characterized by numerous shallow trachyandesitic intrusions of Eocene age. Cognate enclaves in the intrusions consist of monzodiorite and porphyritic trachyandesite. The compositions of these enclaves indicate that they are cumulates formed near the margins of a crustal (possibly midcrustal) magma chamber. The mineral assemblages of the trachyandesitic and monzodioritic enclaves constrain preemplacement temperature to less than 850°C and fO2 to 1 or 2 log units above NNO. H2O contents were probably in the range of 3.0 to 3.5 wt% and the confining pressure of the crustal chamber as much as 5.5 kbar. Xenolithic enclaves include dioritic and anorthositic compositions. These are interpreted to be the wall rocks of the crustal chamber and are probably Precambrian in age. -from Authors

Original languageEnglish
Pages (from-to)1306-1318
Number of pages13
JournalAmerican Mineralogist
Volume76
Issue number7-8
StatePublished - 1991

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