Structural Patterns Associated with the Serpentinites of Southeastern Pennsylvania

Research Article| July 01, 1964 Structural Patterns Associated with the Serpentinites of Southeastern Pennsylvania DAVIS M LAPHAM; DAVIS M LAPHAM Pennsylvania Geological Survey, Harrisburg, Pa. Search for other works by this author on: GSW Google Scholar H LAWRENCE McKAGUE H LAWRENCE McKAGUE College of Mineral Industries, Pennsylvania State University, University Park, Pa. Search for other works by this author on: GSW Google Scholar GSA Bulletin (1964) 75 (7): 639–660. https://doi.org/10.1130/0016-7606(1964)75[639:SPAWTS]2.0.CO;2 Article history received: 04 Feb 1963 first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation DAVIS M LAPHAM, H LAWRENCE McKAGUE; Structural Patterns Associated with the Serpentinites of Southeastern Pennsylvania. GSA Bulletin 1964;; 75 (7): 639–660. doi: https://doi.org/10.1130/0016-7606(1964)75[639:SPAWTS]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 In the Piedmont province of southern Lancaster County, Pennsylvania, equal area, lower hemisphere plots of lineations, and poles to foliations and fractures are compared for serpentinite, areas at the schist-serpentinite contact, and schist. Analysis of the resultant patterns indicates that: shear and strike joints are more numerous in serpentinite than in schist; fractures in the serpentinite are more abundant and more varied than in schist; schist-serpentinite contacts are commonly sheared; near these contacts fracture planes and plunging fold axes tend to be steepened or over-turned to the north; cleavage in schist near serpentinite parallels irregularities in the strike of the serpentinite contact; the major, southeastern serpentinite belt transects the strike of regional cleavage in schist at a small angle; and several deformations have affected both schist and serpentinite.An analysis of the sequential age relationships of serpentinite fractures indicates that two deformational patterns are present that are younger than the final emplacement of the serpentinite.From a discussion of the patterns, it is concluded that: fracture pattern analysis of serpentinites and the surrounding host rock can be utilized in a study of serpentinite tectonics; based upon differences in homogeneity and anisotropy between schist and serpentinite, serpentinites responded to deformational stresses largely as a brittle material; the serpentinite was more responsive than the schist to local stress variations; the final emplacement of the serpentinite was controlled by some pre-existing structural lineament; the superimposed fracture patterns were locally influenced by the south-dipping attitude of the schist-serpentinite contact; and chrysotile veinlets, banded chromite, pegmatites, and deweylite-filled fractures exhibit preferred orientations. 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.