Calcite twinning strains from syn‐faulting calcite gouge: small‐offset strike‐slip, normal and thrust faults

• Published in: International Journal of Earth Sciences
• Main Authors: John P. Craddock, David H. Malone, Jakob Wartman, Megan J. Kelly, Liu Junlai, Maura Bussolotto, Chiara Invernizzi, Jeff Knott, Ryan Porter
• Other Authors: Craddock, John P., Malone, David H., Wartman, Jakob, Kelly, Megan J., Junlai, Liu, Bussolotto, Maura, Invernizzi, Chiara, Knott, Jeff, Porter, Ryan
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2020
• Subjects: Canada; Ellsworth Mountains; Island Lake; Antarc*; Antarctica
• Online Access: https://hdl.handle.net/11581/469436; https://doi.org/10.1007/s00531-019-01783-x; https://link.springer.com/article/10.1007/s00531-019-01783-x

We have evaluated the stress–strain behavior of calcite precipitated and mechanically twinned in small-offset strike-slip, normal and thrust faults of a variety of ages and from a variety of tectonic settings (n = 3001 twin measurements, 63 strain analyses from 18 field sites). Five strike-slip faults with syn-faulting, horizontally striated calcite (rake = 0°) were studied and we report the orientations of the contemporaneous stress–strain field associated with each fault: intrusion of the Marathon Large Igneous Province mafic dikes (~ 2.1 Ga in Archean crust, Minnesota, USA); post-Keweenaw rift (1.1 Ga) faulting (Island Lake fault, central Ontario, Canada); subduction associated with metamorphic core complex formation (Cretaceous, China); subduction (Cretaceous to Miocene, Italy), and continental extension (recently active Furnace Creek fault, Death Valley, California, USA). Seven normal faults with synfaulting, dip-slip striated calcite were studied and are from the following tectonic settings: a normal fault slip surface in an Ordovician Piedmont fold, Appalachian’s; paleo-subduction associated with Cretaceous metamorphic core complex formation (China, 3 sites); the paleo-extensional Atlantic margin (~ 55 Ma, Ireland, 1 site with a U–Pb calcite age); continental extension (1 active site, Mojave desert); a transcurrent margin (Jamaica, 1 active fault site), and subduction [2 active faults along the Eur-African margin in Italy (with calcite U–Th disequilibria ages) and Crete, respectively]. Six thrust fault examples are all from convergent orogenic settings: the basal thrust of the Penokean (1850 Ma) fold-and-thrust belt; the Penokean orogen foreland in Mesabi Range banded iron formation folds; an offset breccia body in the Permian Gondwanide belt, Ellsworth Mountains, Antarctica; the frontal thrust of the Gondwanide Cape belt, South Africa; the Paleocene frontal Prospect thrust, Sevier belt, Wyoming, and an Alpine foreland back-thrust, Lulworth Cove, U.K. For each strike-slip fault system the twinning ...