Regional systematic jointing in slightly deformed sedimentary rocks

Abstract

Research Article| March 01, 1942 Regional systematic jointing in slightly deformed sedimentary rocks JOHN M. PARKER, III JOHN M. PARKER, III Search for other works by this author on: GSW Google Scholar GSA Bulletin (1942) 53 (3): 381–408. https://doi.org/10.1130/GSAB-53-381 Article history received: 29 Oct 1940 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 JOHN M. PARKER; Regional systematic jointing in slightly deformed sedimentary rocks. GSA Bulletin 1942;; 53 (3): 381–408. doi: https://doi.org/10.1130/GSAB-53-381 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search nav search search input Search input auto suggest search filter All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Data on more than 6000 joints cutting the nearly horizontal Paleozoic strata of east, central, and southern New York and northern Pennsylvania reveal three contrasting regional sets. The local consistency of the joint pattern and a gradual regional swing are established. The lack of consistent relationships of the joints to other structures, especially the tracing of a "dip" set across the area into the "strike" position, indicates that the joints formed independently of, and earlier than, the folds, faults, and regional dip. The principal set consists of two conjugate shears intersecting at very acute angles (averaging 19°); its pattern is radiating for the whole area. Theoretical analysis, confirmed by experimental tests, points to an origin by shearing under simultaneous compression and tension acting at right angles. The second set is single and lies about perpendicular to the first, thus forming a pattern of concentric arcs; it originated from tension. These two sets constitute a system of practically contemporaneous fractures. The minor set mantains a constant position for the entire area; it probably is tensional but originated under doubtful circumstances, perhaps at a different time. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not currently have access to this article.