Footwall rocks to the Mid-Tertiary Chemehuevi detachment fault: a window into the middle crust in the Southern Cordillera

B. E. John, S. B. Mukasa

Research output: Contribution to journalArticlepeer-review

25 Scopus citations

Abstract

Crystalline rocks unroofed from the middle crust during Tertiary crustal extension by the Chemehuevi detachment fault record a complex history of both subhorizontal and subvertically foliated mylonitic gneisses sharing a common gently SW-plunging stretching lineation, which are intruded by members of the voluminous laccolith-shaped Chemehuevi Mountains plutonic suite. A belt of steeply foliated mylonitic gneiss up to 5km across, traceable for 12km along strike (NE-SW) crops out in the northern part of the range. Chemehuevi Mountains. Deformation in these two zones took place under upper greenschist to middle amphibolite facies conditions. Contacts within the suite indicate that ductile deformation occurred after intrusion of hornblende-biotite granodiorite. Data constrain the timing of plutonism and ductile deformation, with associated thick zones of fabric reorientation and mylonitic transposition, to the Late Cretaceous. -from Authors

Original languageEnglish (US)
Pages (from-to)463-485
Number of pages23
JournalJournal of Geophysical Research
Volume95
Issue numberB1
DOIs
StatePublished - 1990
Externally publishedYes

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