The importance of diffusion, advection, and host-rock lithology on vein formation: A stable isotope study from the Paleozoic Ouachita orogenic belt, Arkansas and Oklahoma

Abstract

Research Article| November 01, 2002 The importance of diffusion, advection, and host-rock lithology on vein formation: A stable isotope study from the Paleozoic Ouachita orogenic belt, Arkansas and Oklahoma Ian J. Richards; Ian J. Richards 1Stable Isotope Laboratory, Department of Geological Sciences, Southern Methodist University, Dallas, Texas 75275, USA Search for other works by this author on: GSW Google Scholar Jeffrey B. Connelly; Jeffrey B. Connelly 2Department of Earth Sciences, University of Arkansas, Little Rock, Arkansas 72204, USA Search for other works by this author on: GSW Google Scholar Robert T. Gregory; Robert T. Gregory 3Stable Isotope Laboratory, Department of Geological Sciences, Southern Methodist University, Dallas, Texas 75275, USA Search for other works by this author on: GSW Google Scholar David R. Gray David R. Gray 4School of Earth Sciences, University of Melbourne, Melbourne, Victoria 3010, Australia Search for other works by this author on: GSW Google Scholar Author and Article Information Ian J. Richards 1Stable Isotope Laboratory, Department of Geological Sciences, Southern Methodist University, Dallas, Texas 75275, USA Jeffrey B. Connelly 2Department of Earth Sciences, University of Arkansas, Little Rock, Arkansas 72204, USA Robert T. Gregory 3Stable Isotope Laboratory, Department of Geological Sciences, Southern Methodist University, Dallas, Texas 75275, USA David R. Gray 4School of Earth Sciences, University of Melbourne, Melbourne, Victoria 3010, Australia Publisher: Geological Society of America Received: 20 Aug 2001 Revision Received: 26 Feb 2002 Accepted: 26 Mar 2002 First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (2002) 114 (11): 1343–1355. https://doi.org/10.1130/0016-7606(2002)114<1343:TIODAA>2.0.CO;2 Article history Received: 20 Aug 2001 Revision Received: 26 Feb 2002 Accepted: 26 Mar 2002 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 Ian J. Richards, Jeffrey B. Connelly, Robert T. Gregory, David R. Gray; The importance of diffusion, advection, and host-rock lithology on vein formation: A stable isotope study from the Paleozoic Ouachita orogenic belt, Arkansas and Oklahoma. GSA Bulletin 2002;; 114 (11): 1343–1355. doi: https://doi.org/10.1130/0016-7606(2002)114<1343:TIODAA>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 More than 600 stable isotope analyses from veins and their metasedimentary host rocks from the Ouachita orogenic belt of Arkansas and Oklahoma provide an opportunity to study fluid-rock interaction processes associated with vein formation during deformation and low-grade regional metamorphism. The δ18O values of vein quartz vary from 16.0 to 26.4‰, whereas coexisting host rocks have a greater range from 12.9 to 27.4‰. The oxygen isotopic compositions of quartz vein versus those of the coexisting host rocks follow an array described by δ18Ovein quartz ≈ δ18Owhole rock + ε, where ε ≈ 8–0.3(δ18Owhole rock). This relationship emphasizes the dependence of δ18O values of vein quartz on host-rock oxygen isotopic composition. The ε term empirically monitors the difference between the quartz-water fractionation factor and the compositional dependence of the bulk-rock–water fractionation factor. Vein-quartz–host-rock Δ18O fractionations are ∼0‰ in chert, novaculite, quartzite, and siliceous shale and typically between 1 and 4‰ in sandstones and shales. In quartzite and sandstone units that are bounded by shales and associated with significant quartz-crystal deposits, vein-quartz–host-rock fractionations are often unusually large, near 7‰. Quartz-calcite oxygen isotope geothermometry indicates that veins from the Ouachita Mountains formed over a temperature interval of 100 °C, consistent with fluid-inclusion temperatures previously obtained from quartz crystals. Individual quartz veins are homogeneous, with <0.4‰ variation, for all vein orientations at all scales, even though vein formation occurred over a temperature interval in which quartz-water fractionation varies by 5‰. This homogeneity highlights the insensitivity of vein-quartz δ18O values to temperature when veins form under rock-buffered conditions. The similarity between vein and host-rock δ18O values in quartz-rich lithologies, and between vein and host-rock δ13C values in calcite-bearing rocks, indicates that diffusion was an important mass-transport mechanism. The variability in δ18O values between calcite-bearing veins and host rocks and large vein-quartz–whole-rock fractionations in some sandstones and quartzites indicates that advection also played a major role in mass transport associated with vein formation. This inference leads to the interpretation that veins from the Ouachita Mountains formed by a combined diffusion-advection process, whereby 18O and 13C from the host rock was transported into the veins with the assistance of a rock-buffered fluid on outcrop scales of 10–100 m. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.