The Lakeview Mountains Pluton, Southern California Batholith Part I: Petrology and Structure

Research Article| August 01, 1969 The Lakeview Mountains Pluton, Southern California Batholith Part I: Petrology and Structure D. M MORTON D. M MORTON California Division of Mines and Geology, Los Angeles, California Search for other works by this author on: GSW Google Scholar Author and Article Information D. M MORTON California Division of Mines and Geology, Los Angeles, California Publisher: Geological Society of America Received: 11 Nov 1968 Revision Received: 23 Jan 1969 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Copyright © 1969, The Geological Society of America, Inc. Copyright is not claimed on any material prepared by U.S. government employees within the scope of their employment. GSA Bulletin (1969) 80 (8): 1539–1552. https://doi.org/10.1130/0016-7606(1969)80[1539:TLMPSC]2.0.CO;2 Article history Received: 11 Nov 1968 Revision Received: 23 Jan 1969 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation D. M MORTON; The Lakeview Mountains Pluton, Southern California Batholith Part I: Petrology and Structure. GSA Bulletin 1969;; 80 (8): 1539–1552. doi: https://doi.org/10.1130/0016-7606(1969)80[1539:TLMPSC]2.0.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 SocietyGSA Bulletin Search Advanced Search Abstract The Lakeview Mountains pluton, a part of the southern California batholith, is a steep-walled body with a tear-shaped ground plan, exposed discontinuously over an area of 100 to 130 km2. It is located at an abrupt local deflection of the regional structural grain and is concordant with planar structures in the enclosing rocks. These are gabbro, granitic rocks, mixed rock composed of granitic and metamorphic rocks, and regionally metamorphosed rocks of the cordierite-amphibolite facies. Most of the adjacent granitic rocks are older than the Lakeview Mountains pluton, although some may be of the same age.The pluton is almost entirely coarse-grained hornblende-biotite quartz diorite that lacks potassium feldspar. Schlieren are ubiquitous, and small lenticular inclusions, common throughout the pluton, parallel the schlieren. The schlieren, which make the rock extremely inhomogeneous on a small scale, geometrically fall into three orientation groups. One group, the most pronounced, is concordant to the outline of the pluton and planar structures in the adjacent rocks; the other two, discordant with respect to the shape of the pluton, strike northeast and northwest. Some outcrops exhibit schlieren intersecting at a large angle, and mesoscopic fabric analysis indicates that mineral orientation of much of the massive-appearing rocks is complex on the scale of an outcrop.Granitic pegmatite dikes, masses of hypersthene gabbro, and both mafic and leucocratic quartz diorite are concentrated in the geometrically and structurally deduced center of the pluton.It is concluded that the concordant schlieren resulted from outward growth of the pluton and the discordant sets in response to regional forces. The concordance between the outline of the pluton and its wall rocks and the abrupt deflection of the regional structural grain resulted from the outward growth of the pluton. The pegmatite represents the fugitive constituents of the pluton-forming magma, and the sites of pegmatite concentration in the wider part of the tear-shaped body mark the last portions of the pluton to crystallize. 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.