2.7 Ga high-pressure granulites of the Teton Range: Record of Neoarchean continent collision and exhumation

摘要

Continent-continent collisional orogens are the hallmark of modern plate tectonics. The scarcity of well-preserved high-pressure granulite facies terranes minimally obscured by later tectonic events has limited our ability to understand how closely Archean tectonic processes may have resembled better-understood modern processes. Here we describe Neoarchean gneisses in the Teton Range of Wyoming, USA, that record 2.70 Ga high-pressure granulite facies metamorphism, followed by juxtaposition of gneisses with different protoliths, and then by intrusion of leucogranites generated through decompression melting in response to post-collisional uplift. This evidence is best explained as the result of a 2.70–2.68 Ga Himalayan-style orogeny, and suggests that, although subduction may have been occurring earlier in the Archean, doubling of continental thickness by continent-continent collisions may date back to at least 2.7 Ga.