Strain, fractures, and pressure solution in natural single-layer folds

Abstract

Research Article| October 01, 1975 Strain, fractures, and pressure solution in natural single-layer folds R. H. GROSHONG, JR. R. H. GROSHONG, JR. 1Cities Service Oil Company, Exploration & Production Research, Box 50408, Tulsa, Oklahoma 74150 Search for other works by this author on: GSW Google Scholar Author and Article Information R. H. GROSHONG, JR. 1Cities Service Oil Company, Exploration & Production Research, Box 50408, Tulsa, Oklahoma 74150 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1975) 86 (10): 1363–1376. https://doi.org/10.1130/0016-7606(1975)86<1363:SFAPSI>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 MailTo Tools Icon Tools Get Permissions Search Site Citation R. H. GROSHONG; Strain, fractures, and pressure solution in natural single-layer folds. GSA Bulletin 1975;; 86 (10): 1363–1376. doi: https://doi.org/10.1130/0016-7606(1975)86<1363:SFAPSI>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 Intragranular strain has been measured by the twinned calcite strain-gage technique from the hinges and limbs of three single-layer minor folds with limb dips of 15°, 48°, and 67°. The folds are in unmetamorphosed, Silurian-age limestone beds enclosed in shale, in the Appalachian Valley and Ridge province of central Pennsylvania. In all three folds, the maximum compressive strain axes are subparallel to bedding and tend to plunge toward the inner arcs of the hinges. The principal deviatoric compressive strains in the fold cross sections range from −0.48 ± 0.77 to −4.75 ± 0.78 percent; the largest compressive strains are in the gentlest fold and the smallest ones are in the tightest fold. Syntectonic stylolites are abundant in the folds and approximate a fanning cleavage. Filled extension fractures occur normal to bedding on the outer arc of the hinges of the two tightest folds. Filled fractures on the limbs of the same folds began as extension fractures subparallel to bedding and evolved into throughgoing thrust faults. A significant amount of the folding deformation is evidently accomplished by pressure solution and by displacement on fractures.The folds are interpreted as buckle folds and distinguished from transverse bends and passive folds on the basis of the mechanical contrast between the limestone and enclosing shale beds and the orientation and distribution of the principal strain axes, stylolites, and fractures. The orientations of the principal strain axes are best fit by buckle-fold models. Strain models of pure bending, layer-parallel shear, and shear parallel to the hinge plane are shown to be inadequate by themselves even as first-order approximations.A simple rheological model including intragranular strain (twin and translation gliding, grain boundary adjustments) and pressure solution fits the inferred relationships between these features. The model presumes that intragranular strain has a yield stress, whereas pressure solution does not, and that at high stresses pressure solution is more important than intragranular strain. The model predicts that when conditions are suitable for pressure solution, more of the strain will occur by this mechanism than by twin gliding and related mechanisms. This can explain the overall low values of measured intragranular strain. 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.