CaltechAUTHORS
  A Caltech Library Service

Structural petrology of the Val Verde tonalite, southern California

Osborn, E. F. (1939) Structural petrology of the Val Verde tonalite, southern California. Geological Society of America Bulletin, 50 (6). pp. 921-950. ISSN 0016-7606. https://resolver.caltech.edu/CaltechAUTHORS:20191120-160259174

[img] PDF - Published Version
See Usage Policy.

6Mb

Use this Persistent URL to link to this item: https://resolver.caltech.edu/CaltechAUTHORS:20191120-160259174

Abstract

Micrometric analyses of the Val Verde tonalite were made on samples taken along a line extending from the border of the intrusive to a point 5 miles out in the intrusive. An attempt was made to evaluate sampling errors and to determine variation in mineralogic composition and radioactivity. The border of the intrusive was found to be more sodic and higher in radioactivity than the central part, and this is thought to be due to assimilation of quartz-biotite schist. Inclusions in the tonalite are believed to be xenoliths of gabbro and quartz-biotite schist. Petrofabric analyses of the schist country rock and the tonalite indicate that : (1) the schist was deformed primarily by rotation of mineral grains about a horizontal axis; (2) during intrusion of the tonalite a gneissoid structure developed in it parallel to the contact with the country rock with a linear element lying in the plane of foliation and paralleling the dip; (3) later stresses directed parallel to the strike of the foliation caused rotation of mineral grains in the tonalite about an axis parallel to the dip. The orientation of the minerals in the tonalite is thus believed to be due to a combination of magmatic flow and post-magmatic deformation.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1130/gsab-50-921DOIArticle
Additional Information:© 1939 Geological Society of America. Manuscript received by the Secretary of the Society, November 2, 1938.
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Balch Graduate School of the Geological Sciences267
Issue or Number:6
Record Number:CaltechAUTHORS:20191120-160259174
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20191120-160259174
Official Citation:E. F. OSBORN; Structural petrology of the Val Verde tonalite, southern California. GSA Bulletin ; 50 (6): 921–950. doi: https://doi.org/10.1130/GSAB-50-921
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:99967
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:21 Nov 2019 03:46
Last Modified:27 Apr 2020 19:16

Repository Staff Only: item control page