PETROTECTONIC EVOLUTION OF THE PRECAMBRIAN FARMINGTON CANYON COMPLEX OF NORTHERN UTAH

Geochemical, geochronologic, and isotopic analyses from basement rocks of the Farmington Canyon Complex (FCC), exposed in the Wasatch Mountains and on Antelope Island in northern Utah, are underway to better understand the Archean to Paleoproterozoic assembly of western Laurentia. The FCC comprises a complex mix of orthogneiss, paragneiss, amphibolite, and late-stage granites. Although prior work has established input of Archean materials and Paleoproterozoic metamorphism of the FCC, maximum depositional ages and sediment sources of paragneiss and associated meta-quartzite remain poorly understood, as well as relations to surrounding Archean blocks. Samples of paragneiss, orthogneiss, and amphibolite have been systematically collected from different parts of the FCC, based on geologic mapping and structural relations, and prepared for integrated U-Pb geochronologic and Hf isotopic analysis of igneous, metamorphic, and detrital zircon components. Major, minor, and trace element geochemical analysis of whole rock samples and minerals is also in progress. These data sets, along with comparison to existing data from the Archean Wyoming province, will constrain timing of crustal extraction and subsequent reworking by igneous and metamorphic processes, and improve understanding of how basement blocks were amalgamated in western Laurentia.