Neoarchean tectonic history of the Teton Range: Record of accretion against the present-day western margin of the Wyoming Province

作者：Frost B Ronald^*; Swapp Susan M; Frost Carol D; Bagdonas Davin A; Chamberlain Kevin R

来源：Geosphere, 2018, 14(3): 1008-1030.

DOI：10.1130/GES01559.1

Although Archean gneisses of the Teton Range crop out over an area of only 50 x 15 km, they provide an important record of the Archean history of the Wyoming Province. The northern and southern parts of the Teton Range record different Archean histories. The northern Teton Range preserves evidence of 2.69-2.68 Ga high-pressure granulite metamorphism (>12 kbar, similar to 900 degrees C) followed by tectonic assembly with isotopically juvenile quartzofeldspathic metasedimentary rocks under high-pressure amphibolite-facies conditions (similar to 7 kbar, 675 degrees C) and intrusion of extensive leucogranites. Together, these events record one of the oldest continent-continent collisional orogenies on Earth. Geochemical, thermobarometric, and geochronological data from the gneisses of the southern Teton Range show that this part of the uplift records a geologic history that is distinct from the northern part. It contains a variety of quartzofeldspathic gneisses, including a 2.80 Ga granodioritic orthogneiss and the 2.69-268 Ga Rendezvous Gabbro. None of these preserves evidence of the granulite metamorphism seen in the northern Teton Range. Instead, they have affinities with rocks elsewhere in the Wyoming Province. The boundary between the northern and southern areas is occupied by the Moran deformation zone, a broad zone of high strain along which the northern and southern areas were assembled at ca. 2.62 Ga under moderate pressures and temperatures (T = 540-600 degrees C and P < 5.0 kbar). The final Archean event of the Teton Range was the emplacement at 2.55 Ga of the Mount Owen batholith, a peraluminous leucogranite that intrudes the Moran deformation zone.
The rocks of the northern Teton Range record events that are not present elsewhere in the Wyoming Province. We propose that they formed at 2.70-2.67 Ga some place distal to the Wyoming Province and that they were accreted from the west against the Wyoming Province along the Moran deformation zone at ca. 2.62 Ga. This date is coeval with deformation and metamorphism in the southern accreted terranes and indicates that at this time, accretion was taking place along both the southern margin and western margins of the Wyoming Province.

• 出版日期2018-6