STATISTICAL METHODS APPLIED TO THE STUDY OF ROCK FRACTURES

Abstract

Listen

Translate article

Research Article| February 01, 1951 STATISTICAL METHODS APPLIED TO THE STUDY OF ROCK FRACTURES: QUANTITATIVE COMPARATIVE ANALYSIS OF FRACTURES IN GNEISSES AND OVERLYING SEDIMENTARY ROCKS OF NORTHERN NEW JERSEY HOWARD J PINCUS HOWARD J PINCUS OHIO STATE UNIVERSITY, COLTJMBUS, OHIO Search for other works by this author on: GSW Google Scholar Author and Article Information HOWARD J PINCUS OHIO STATE UNIVERSITY, COLTJMBUS, OHIO Publisher: Geological Society of America Received: 14 Sep 1949 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Copyright © 1951, 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 (1951) 62 (2): 81–130. https://doi.org/10.1130/0016-7606(1951)62[81:SMATTS]2.0.CO;2 Article history Received: 14 Sep 1949 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 HOWARD J PINCUS; STATISTICAL METHODS APPLIED TO THE STUDY OF ROCK FRACTURES: QUANTITATIVE COMPARATIVE ANALYSIS OF FRACTURES IN GNEISSES AND OVERLYING SEDIMENTARY ROCKS OF NORTHERN NEW JERSEY. GSA Bulletin 1951;; 62 (2): 81–130. doi: https://doi.org/10.1130/0016-7606(1951)62[81:SMATTS]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 A quantitative analysis of fracture-orientation data collected in Precambrian gneisses and overlying lower Paleozoic sedimentary rocks in three northern New Jersey areas yields the following results: (1) The data, as plotted on both rectangular co-ordinates and the Schmidt equal-area net, show definite clustering for all localities studied; the Poisson Exponential Binomial Limit is applied to test for significant departure of the diagrams from isotropism, to estimate mean orientations of fracture sets (mean fracture planes), and to aid in interpreting the rectangular point diagrams. (2) Fractures and foliations in the crystalline rocks do not appear to be genetically related. (3) Most localities have two principal joint sets, but there are proportionately more Precambrian than Paleozoic localities with three sets. (4) The Paleozoic localities show more concentrated clustering on the point diagrams. (5) The dihedral angle between mean fracture planes and bedding is typically near 90 degrees; the dihedral angle between mean fracture planes and foliation has no typical value. (6) The angle of fracture in both rock types appears to be independent of the nature of the rock. (7) Contrasts in rock type (metamorphic vs. overlying sedimentary) are usually accompanied by striking differences in point-diagram patterns. (8) The measurement of a few large fractures gives no better approximation of the mean fracture planes than the measurement of an equal number of fractures of any size. (9) The trends of mean fracture planes conform with linear features visible on air photographs. (10) A high proportion of fractures dip steeply; dips in the crystalline rocks are systematically smaller than those in the overlying sedimentary rocks.The fractures in the gneisses are probably older than those in the sedimentary rocks.The deformation of the gneisses seems to have taken place through mechanisms fundamentally different from those involved in deforming the overlying sedimentary rocks. 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.