Skip to Main Content
Skip Nav Destination
GEOREF RECORD

Statistical methods applied to the study of rock fractures [New Jersey]

Howard Jonah Pincus
Statistical methods applied to the study of rock fractures [New Jersey]
Bulletin of the Geological Society of America (February 1951) 62 (2): 81-129

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.


ISSN: 1050-9747
Coden: BUGMAF
Serial Title: Bulletin of the Geological Society of America
Serial Volume: 62
Serial Issue: 2
Title: Statistical methods applied to the study of rock fractures [New Jersey]
Pages: 81-129
Published: 195102
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
Accession Number: 1959-024394
Categories: Structural geology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus.
N38°55'00" - N41°21'00", W75°34'60" - W73°52'60"
Source Note: discussion by J. Rodgers and reply by author, p. 427-434, Apr. 1952.
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute. Reference includes data from Bibliography and Index of North American Geology, U. S. Geological Survey, Reston, VA, United States
Update Code: 1959
Close Modal

or Create an Account

Close Modal
Close Modal