Crack-propagation sequence and pore-fluid conditions during fault-bend folding in the Appalachian Valley and Ridge, central Pennsylvania

Abstract

Research Article| January 01, 1990 Crack-propagation sequence and pore-fluid conditions during fault-bend folding in the Appalachian Valley and Ridge, central Pennsylvania DEEPAK C. SRIVASTAVA; DEEPAK C. SRIVASTAVA 1Department of Geosciences, Pennsylvania State University, University Park, Pennsylvania 16802 Search for other works by this author on: GSW Google Scholar TERRY ENGELDER TERRY ENGELDER 1Department of Geosciences, Pennsylvania State University, University Park, Pennsylvania 16802 Search for other works by this author on: GSW Google Scholar Author and Article Information DEEPAK C. SRIVASTAVA 1Department of Geosciences, Pennsylvania State University, University Park, Pennsylvania 16802 TERRY ENGELDER 1Department of Geosciences, Pennsylvania State University, University Park, Pennsylvania 16802 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1990) 102 (1): 116–128. https://doi.org/10.1130/0016-7606(1990)102<0116:CPSAPF>2.3.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation DEEPAK C. SRIVASTAVA, TERRY ENGELDER; Crack-propagation sequence and pore-fluid conditions during fault-bend folding in the Appalachian Valley and Ridge, central Pennsylvania. GSA Bulletin 1990;; 102 (1): 116–128. doi: https://doi.org/10.1130/0016-7606(1990)102<0116:CPSAPF>2.3.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 Bedding-parallel (BPV), strike (SV), and cross-fold (CFV) veins represent a sequence of polyphase fracturing during the development of a fault-bend fold in lower Paleozoic carbonate beds in the Appalachian Valley and Ridge province, Pennsylvania. Brecciation and layer-parallel shearing played important roles in the development of the earliest vein set (BPV) which propagated prior to folding. Fluid inclusions in calcite BPV are highly saline brines (23.4 wt% NaCI) trapped at conditions close to lithostatic (P ≤ 180 MPa, T ≤ 267 °C). While passing through the lower kink plane of a fault-bend fold, strike joints propagated in dolomitic beds located on the extensional side of neutral surfaces. Stylolitization of strike joint surfaces accompanied slip of the hanging wall up a ramp. Renewed extension upon passing through a second kink plane led to propagation of antitaxial SV along the stylolitized joints by the crack-seal process. Slightly less saline fluids (22.4 wt% NaCI) were trapped in SV at fluid pressures ≤144 MPa and temperatures ≤217 °C. With the concurrent formation of lateral ramps, the carbonates moved to the upper flat and were subjected to strike parallel extension as manifested by the propagation of antitaxial CFV. Due to further mixing of fresh waters, the salinity of fluids forming CFV decreased (20.5 wt% NaCl) with trapping conditions at P ≤ 116 MPa and T ≤ 179 °C. The fluid evolution path from BPV to CFV through SV shows a modest decrease in salinity with a sharp decrease in possible trapping pressures. 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.