Towards a better understanding of the influence of basement heterogeneities and lithospheric coupling on foreland deformation: A structural and paleomagnetic study of Laramide deformation in the southern Bighorn Arch, Wyoming

Abstract

Research Article| March 01, 2014 Towards a better understanding of the influence of basement heterogeneities and lithospheric coupling on foreland deformation: A structural and paleomagnetic study of Laramide deformation in the southern Bighorn Arch, Wyoming Arlo Brandon Weil; Arlo Brandon Weil † 1Department of Geology, Bryn Mawr College, Bryn Mawr, Pennsylvania 19010, USA †E-mail: aweil@brynmawr.edu Search for other works by this author on: GSW Google Scholar Adolph Yonkee; Adolph Yonkee 2Department of Geosciences, Weber State University, Ogden, Utah 84408, USA Search for other works by this author on: GSW Google Scholar Jamie Kendall Jamie Kendall 1Department of Geology, Bryn Mawr College, Bryn Mawr, Pennsylvania 19010, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Arlo Brandon Weil † 1Department of Geology, Bryn Mawr College, Bryn Mawr, Pennsylvania 19010, USA Adolph Yonkee 2Department of Geosciences, Weber State University, Ogden, Utah 84408, USA Jamie Kendall 1Department of Geology, Bryn Mawr College, Bryn Mawr, Pennsylvania 19010, USA †E-mail: aweil@brynmawr.edu Publisher: Geological Society of America Received: 17 Feb 2013 Revision Received: 05 Sep 2013 Accepted: 07 Oct 2013 First Online: 08 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 © 2014 Geological Society of America GSA Bulletin (2014) 126 (3-4): 415–437. https://doi.org/10.1130/B30872.1 Article history Received: 17 Feb 2013 Revision Received: 05 Sep 2013 Accepted: 07 Oct 2013 First Online: 08 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 Arlo Brandon Weil, Adolph Yonkee, Jamie Kendall; Towards a better understanding of the influence of basement heterogeneities and lithospheric coupling on foreland deformation: A structural and paleomagnetic study of Laramide deformation in the southern Bighorn Arch, Wyoming. GSA Bulletin 2014;; 126 (3-4): 415–437. doi: https://doi.org/10.1130/B30872.1 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 SocietyGSA Bulletin Search Advanced Search Abstract Integrated structural, anisotropy of magnetic susceptibility (AMS), and paleomagnetic analyses of sedimentary cover rocks along variably oriented major faults and en echelon fold systems in the southern Bighorn Arch, Wyoming, were undertaken to test kinematic and mechanical models of Laramide thick-skin deformation. The Laramide foreland is characterized by an anastomosing network of basement-cored arches and associated cover folds that trend overall NW-SE, but in detail are curved, range from N-S to E-W trending, and form both right- and left-stepping en echelon systems. Development of variably trending Laramide arches has been variously attributed to temporal changes in stress directions, wrench faulting, and localization of deformation related to basement heterogeneities during regional SW-NE shortening. Within the southern Bighorn Arch, widespread but limited layer-parallel shortening (LPS) was accommodated mostly by minor faults with conjugate wedge and strike-slip geometries early in the deformation history. LPS directions vary from perpendicular to acute with local fold structural trends, consistent with a single shortening episode. Although internal strain is limited, weak AMS lineations defined by kinked and rotated phyllosilicates are widely developed and consistently perpendicular to LPS directions. Structurally restored paleomagnetic declinations record only limited, non-systematic vertical-axis rotations, indicating that wrenching was not an important component of the deformation field during development of the southern Bighorn Arch and that curvature of the arch was a primary feature. Palinspastically restored LPS directions are on average WSW-ENE, but display local deflections related to heterogeneities of underlying basement blocks and proximity to major faults, some of which were localized along Precambrian shear zones and igneous dikes. Crustal shortening patterns across the Laramide foreland are interpreted to reflect deformation partitioning in response to a single far-field shortening direction partly related to flat-slab subduction along with effects of pre-existing basement weaknesses and strain softening during progressive faulting. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.