Orogenic remagnetizations in the Front Ranges and Inner Foothills of the southern Canadian Cordillera: Chemical harbinger and thermal handmaiden of Cordilleran deformation

摘要: ABSTRACT Paleomagnetic studies of carbonate rocks in mountain belts have been helpful to the understanding orogenic mational origin. With only one exception, A component has normal polarity Front Ranges and reverse processes, timing deformation, nature fluid flow actively deforming foreland basins. Most on shallow-water carbonates indicate that their remanence is not primary, but rather they record remagnetization events contemporaneous with orogeny. By considering remanent directions, fold test results, rock magnetic properties, tying these results complementary structural, geochronological geochemical studies, we are able interpret deformation history, hydrological environment, diagenesis. We study relationship between Paleozoic Inner Foothills southern Canadian Rockies. The properties remarkably constant along 500 km strike length, as sampled at 124 sites through 4 transects. Primary directions which would shallow inclination, never observed. Rather, paleomagnetic signal dominated by geographically persistent remagnetizations, characterized steep inclination. As well a soft present field overprint, observed two distinctive secondary magnetizations, named B components, carried fine-grained magnetite. Pervasive diagenesis induced component, total chemical remagnetization. Poles for better concentrated after bedding correction indicating pre- or early syndefor-polarity Foothills. Pole positions, polarity, geological thermal constraints was acquired diachronously advance eastward migrating Cordilleran tectonic wedge. Subsequently, an intermediate temperature partial thermo-remanent remagnetization, superimposed large regions brought into optimal concentration differential untilting 0% 50%, were incorporated wedge, before end contractional deformation. strongest within couple kilometers frontal thrust Ranges. relative magnitude components maximum unblocking decrease away from over about 30 km, both west east. overprint attained <250°C heating response tectonic, possibly sedimentary, loading. It preserved rapid cooling accompanying uplift erosion up 8 vicinity late in, post-dating, its local tilting history. likely cause exposed structural panel contraction younger underlying structures.