Title: Structural reconstruction and zonation of a tilted mid-crustal magma chamber: The felsic Chemehuevi Mountains plutonic suite
Abstract: Research Article| July 01, 1988 Structural reconstruction and zonation of a tilted mid-crustal magma chamber: The felsic Chemehuevi Mountains plutonic suite Barbara E. John Barbara E. John 1Department of Geological Sciences University of California, Santa Barbara, California 93106 Search for other works by this author on: GSW Google Scholar Author and Article Information Barbara E. John 1Department of Geological Sciences University of California, Santa Barbara, California 93106 Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1988) 16 (7): 613–617. https://doi.org/10.1130/0091-7613(1988)016<0613:SRAZOA>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Barbara E. John; Structural reconstruction and zonation of a tilted mid-crustal magma chamber: The felsic Chemehuevi Mountains plutonic suite. Geology 1988;; 16 (7): 613–617. doi: https://doi.org/10.1130/0091-7613(1988)016<0613:SRAZOA>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Structural relief resulting from middle Tertiary extensional deformation in the Chemehuevi Mountains of California exposes a unique cross section through an extensive (>280 km2) calc-alkalic, compositionally zoned, sill-like granitic intrusion of Late Cretaceous age. Minimum estimates for emplacement pressure, 4 to 6 kbar, imply that the Chemehuevi Mountains plutonic suite was initially intruded at mid-crustal depths and has undergone 10° to 15° of postemplacement tilting, tectonic denudation, and erosion. Reconstruction of the pre-Tertiary (pre-tilt) configuration suggests that this metaluminous to peraluminous granitic suite exhibits crude normal, vertical, and temporal zonation from granodiorite to granite. The zonation involves a decrease in age and an increase in silica away from the walls and roof, the youngest and most evolved members being concentrated toward the center and floor of the intrusion. The lower part of the intrusion had a flat floor, which was penetrated by at least three feeder dikes providing magma to the chamber. The chamber grew laterally in stages, each pulse being more evolved than the preceding one. Structural reconstruction indicates that the roof is less than 1 km above the exposed top of the intrusion, suggesting a tabular geometry with an aspect ratio of about 5:1. The magma apparently ponded along the contact between undeformed Proterozoic basement above and subhorizontally foliated mylonitic gneisses below, and was therefore structurally controlled. This reconstruction provides information on the geometry of mesozonal intermediate to silicic magma chambers. In addition, the restoration provides a rare opportunity to observe crosscutting relations between different types of mid-crustal structures (thick mylonitic shear zones, granitic intrusions, and temporally unrelated detachment faults), the geometry of which emphasizes the need for careful evaluation of seismic reflection profiles across complexly deformed and intruded continental crust. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.
Publication Year: 1988
Publication Date: 1988-01-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 54
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