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|Title:||Geology of the Wilson Peak stock, San Miguel Mountains, Colorado|
|Author(s):||Bromfield, Calvin Stanton|
|Genre:||Dissertation / Thesis|
Advisor: Arthur F. Hagner, Geology Department.
Dissertation (Ph.D.)--University of Illinois at Urbana-Champaign, 1962.
Includes bibliographical references (leaves 149-154).
The San Miguel Mountains, a western outlier of the larger San Juan Mountain region, is in San Miguel and Dolores Counties, southwest Colorado ... Mapping in the San Miguel Mountains was done by the U. S. Geological Survey as a part of a larger project of mapping in the western San Juan Mountains under the direction of A. L. Bush. Reports have been published on the Placerville quadrangle ... and the Little Cone quadrangle ... The writer was in charge of the investigation of the Mount Wilson quadrangle and is solely responsible for the conclusions set forth in this paper.
In addition to mapping the area , one of the primary purposes of the present study was to determine the structural relations of the stock and its associated intrusive rocks to the bedded rocks, and to see what information they gave as to the mode of emplacement of the igneous rocks. Another objective was to study the variation in rock types noted by Cross and to determine their mutual relations to one an other, and, if feasible, to separate them in mapping.
The stock was found to be composite , consisting of at least three separate and distinct intrusions, rather than due to variation in the original magma as thought by Cross ... , and as restated by Larsen and Cross ... The stock was found to intrude rocks as young as the Miocene(?) Silverton volcanic series. The associated Ames pluton, which extends as a narrow arm east from the stock, and the Black Face pluton to the south are regarded as due to a fourth and slightly older intrusion. The igneous rocks were emplaced at relatively shallow depths. The Black Face-Ames plutons are primarily concordant and made room for themselves by doming or lifting their roofs and by pushing aside of strata. The Wilson Peak stock was emplaced, at least in final stages, by piecemeal stoping with little disturbance of the surrounding bedded rocks. In this paper the bedded rocks and intrusive rocks are described, the petrogenesis of the stock and associated intrusives are discussed, and the structure and mode of emplacement of the igneous rocks are set forth. Edited summary from dissertation introduction.
|Rights Information:||Copyright 1962 Calvin Stanton Bromfield|
|Date Available in IDEALS:||2017-11-30|
|Identifier in Online Catalog:||6203752|
This item appears in the following Collection(s)
Graduate Dissertations and Theses at Illinois
Graduate Theses and Dissertations at Illinois