A history of cleavage and folding: An example from the Goldenville Formation, Nova Scotia

Abstract

Research Article| November 01, 1986 A history of cleavage and folding: An example from the Goldenville Formation, Nova Scotia J. R. HENDERSON; J. R. HENDERSON 1Geological Survey of Canada, Ottawa, Canada K1A OE8 Search for other works by this author on: GSW Google Scholar T. O. WRIGHT; T. O. WRIGHT 2U.S. National Science Foundation, Washington, D.C. 20550 Search for other works by this author on: GSW Google Scholar M. N. HENDERSON M. N. HENDERSON 3Geological Survey of Canada, Ottawa, Canada Kl A OE8 Search for other works by this author on: GSW Google Scholar Author and Article Information J. R. HENDERSON 1Geological Survey of Canada, Ottawa, Canada K1A OE8 T. O. WRIGHT 2U.S. National Science Foundation, Washington, D.C. 20550 M. N. HENDERSON 3Geological Survey of Canada, Ottawa, Canada Kl A OE8 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1986) 97 (11): 1354–1366. https://doi.org/10.1130/0016-7606(1986)97<1354:AHOCAF>2.0.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation J. R. HENDERSON, T. O. WRIGHT, M. N. HENDERSON; A history of cleavage and folding: An example from the Goldenville Formation, Nova Scotia. GSA Bulletin 1986;; 97 (11): 1354–1366. doi: https://doi.org/10.1130/0016-7606(1986)97<1354:AHOCAF>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 Temporal relationships between cleavage formation and folding in sedimentary rock sequences can vary from either phenomena preceding the other to both occurring simultaneously. Knowledge of this relationship, however, is required to understand fully the relationship of cleavage orientation to finite strain and the origin of cleavage refraction across competent-incompetent layers. Evidence from the Goldenville Formation provides an example of cleavage formed before folding by ∼50% pressure-solution removal of material, resulting in cleavage planes normal to bedding during active folding. This layer-parallel shortening was accompanied by excess pore pressure that in some cases, exceeded lithostatic pressure, causing formation of bedding-parallel quartz veins with crack-seal textures. Folds developed by a mechanism of differential flexural flow with no loss of coherence across bedding surfaces. En echelon veins formed sequentially across some beds during active folding and subsequently were deformed by various increments of bedding-parallel shear. After folds reached ∼80° limb dips, continued horizontal shortening was accommodated by additional pressure solution, but no recognizable new cleavage was formed. Because cleavage in the Goldenville Formation formed perpendicular to bedding before folding and was passively rotated and extended by bedding-parallel simple shear during fold amplification, the resulting cleavage planes cannot lie in the XY plane of the finite-strain ellipsoid. Differential shear between metagray-wacke and slate beds accounts for the observed cleavage refraction, and the bedding-cleavage angle provides a good estimate of the shearing across these beds during active folding. If cleavage can be shown to postdate folding in other examples, it is possible that cleavage planes will lie in the XY plane of the finite-strain ellipsoid. 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.