Depth Control of Some Concordant Intrusions

Abstract

Research Article| March 01, 1968 Depth Control of Some Concordant Intrusions MELVILLE R MUDGE MELVILLE R MUDGE U. S. Geological Survey, Denver, Colorado Search for other works by this author on: GSW Google Scholar Author and Article Information MELVILLE R MUDGE U. S. Geological Survey, Denver, Colorado Publisher: Geological Society of America Received: 27 Dec 1966 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Copyright © 1968, 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 (1968) 79 (3): 315–332. https://doi.org/10.1130/0016-7606(1968)79[315:DCOSCI]2.0.CO;2 Article history Received: 27 Dec 1966 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation MELVILLE R MUDGE; Depth Control of Some Concordant Intrusions. GSA Bulletin 1968;; 79 (3): 315–332. doi: https://doi.org/10.1130/0016-7606(1968)79[315:DCOSCI]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 Analysis of geologic data from 54 localities, mainly in the western United States, shows that concordant igneous masses intruded zones in nearly flat-lying sedimentary rocks where the thickness of cover was 3000 to 7500 feet. The depth of intrusion was apparently affected by a well-defined parting surface (bedding plane or unconformity), static load of the overburden (lithostatic pressure), and presence of a fluid barrier above the intrusion.Most bodies intruded along well-defined bedding planes in sedimentary rocks and flow surfaces in extrusive igneous rocks; some intruded along unconformities. The range in overburden pressure is about 3000 to 7500 psi for intrusions at depths of 3000 to 7500 feet. Magma pressure for lateral injection at the lower limit of the depth range, therefore, must have exceeded 7500 psi to lift 7500 feet of overburden. A fluid barrier, such as a shale, overlies almost all intrusions studied and tended to retard upward advance of magma. At depths less than 3000 feet, the barrier shales may be brittle and easily ruptured by the fluid pressure, permitting steam and magma to escape to the surface. Below 3000 feet the shales may become ductile. 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.