Evidence for temporally changing mechanical stratigraphy and effects on joint-network architecture

Research Article| February 01, 2005 Evidence for temporally changing mechanical stratigraphy and effects on joint-network architecture J. Ryan Shackleton; J. Ryan Shackleton 1Department of Geosciences, University of Massachusetts, Amherst, Massachusetts 01003, USA Search for other works by this author on: GSW Google Scholar Michele L. Cooke; Michele L. Cooke 1Department of Geosciences, University of Massachusetts, Amherst, Massachusetts 01003, USA Search for other works by this author on: GSW Google Scholar Aviva J. Sussman Aviva J. Sussman 2Department of Geosciences, University of Arizona, Tucson, Arizona 85721, USA Search for other works by this author on: GSW Google Scholar Geology (2005) 33 (2): 101–104. https://doi.org/10.1130/G20930.1 Article history received: 22 Jun 2004 rev-recd: 11 Oct 2004 accepted: 12 Oct 2004 first online: 09 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 J. Ryan Shackleton, Michele L. Cooke, Aviva J. Sussman; Evidence for temporally changing mechanical stratigraphy and effects on joint-network architecture. Geology 2005;; 33 (2): 101–104. doi: https://doi.org/10.1130/G20930.1 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 SocietyGeology Search Advanced Search Abstract Previous studies of jointing in sedimentary rocks have shown that joint-network architecture is controlled by mechanical stratigraphy, which is described by (1) the thickness and rigidity of stratigraphic units and (2) the nature of interfaces between beds. Using joint pattern to infer rigidity contrast between beds is complicated by the possibility that material properties of the beds may change between fracturing events. Observation of both an early bed-contained joint set and a differently oriented late throughgoing joint set in the same beds of growth strata in the Oliana anticline in the Spanish Pyrenees may reflect changing mechanical properties (i.e., via diagenesis) during the folding process. Using a Schmidt hammer, we assess the rigidity contrast between the individual units and show that the present-day contrast is not great enough to terminate joints at interfaces. This result is consistent with an interpretation that the late-stage throughgoing joints formed in strata with conditions similar to those of the present day and that the early bed-contained joints formed when the rigidity contrast between beds was significantly greater than that of the present day. For example, differential diagenesis rates between layers of differing grain size would produce temporally changing mechanical stratigraphy. We propose that changes in mechanical stratigraphy may have previously been unrecognized in other stratigraphic sections and that these changes affect joint-network architecture and subsequent fluid-flow pathways. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.