3430 to 3417 Ma calc-alkaline volcanism in the McPhee Dome and Kelly Belt, and growth of the eastern Pilbara Craton

摘要: Abstract The McPhee Dome and Kelly Belt in the eastern Pilbara Craton contain well-preserved, proximal, shallow-marine, dominantly-intermediate, volcanic successions. These have SHRIMP UPb zircon ages of 3430 ± 3 3417 9 Ma respectively, which are younger than geochemically similar ∼3.52 ∼3.47 to 3.45 Ga suites other greenstone belts. Basalts, andesites dacites from composition modern arc rocks, whereas rhyodacites geochemical characteristics Archaean tonalite-trondhjemite-granodiorite (TTG) magmas. geochemistry basalts, basaltic most likely reflects infracrustal fractional crystallization a mantle derived magma combined with assimilation older crust, or silicic melt. In contrast were by melting subducted mafic crust. extensional submarine environment pre-3.4 Ga, dominantly intermediate volcanism differs that approximately coeval granitoid magmatism. granitoids major trace element features TTG appear been emplaced into already thick crust culminating core complex formation. Available data consistent growth convergent tectonic settings, involving pulses arc-like between 3.52 3.42 overlapping with, and/or punctuated by, periods crustal thickening intrusion batholiths.