Petrogenesis of late-Paleoproterozoic A -type granites in the Tarim Craton and implications for the Columbia assembly and break-up

Lots of late-Paleoproterozoic magmatic and tectonic records, which are commonly interpreted as products of the Columbia assembly and break-up, were preserved in the Tarim Craton. In this study, we summarized the late-Paleoproterozoic A-type granitoids at the periphery of the Tarim Craton, and identified two A-type granitoid flare-ups at 1. 95Ga and 1. 85 similar to 1. 73Ga. All these A-type granitoids are derived from partial melting of the crustal materials with tonalitic to granodioritic compositions. The ca. 1. 95Ga granites show high SiO2 and Sr contents, high Y/Nb and Ce/Nb ratios, low epsilon(Hf) ( t) values (- 13 similar to- 5. 2), and could be classified as A2 subtype granitoid. They were formed in continental arc or back-arc settings. The 1. 85 similar to 1. 73Ga granites show relatively low SiO2 and Sr contents, low Y/Nb and Ce/Nb ratios, high eHf (t) (-5. 9 similar to +8. 7) and epsilon(Nd) ( t) (-6. 2 similar to-2. 5) values, and could be classified as A2 to Al transitional subtype. They were formed in post-collisional or intracontinental extension settings. Besides, magmatism and metamorphism ages in the Tarim Craton also show two peaks at 1. 93Ga and 1. 85Ga, 1. 95Ga and 1. 84Ga, respectively. These age data suggest that the Tarim Craton may have experienced two significant tectono-magmatic events at about 1. 93Ga and 1. 85Ga. These two events may record the subduction related orogeny and collisional orogeny, and are related to the Columbia assembly and break-up, respectively. We believed that the Columbia supercontinent may have broken up at 1. 85Ga.

Automated summary

This study summarized the late-Paleoproterozoic A-type granitoids at the periphery of the Tarim Craton and identified two A-type granitoid flare-ups. These granitoids were formed in continental arc or back-arc settings, or post-collisional or intracontinental extension settings.