Tectonothermal model and magmatism evolution of the postcollisional (pre-plume) development stage of the Kara orogen (Northern Taimyr, Central Arctic)

Abstract

We consider a tectonothermal model and the evolution of magmatism during the late Paleozoic postcollisional (pre-plume) development stage of the Kara orogen in northern Taimyr, Central Arctic. The model is based on new and published structural, petrologic, geochemical and geochronological data, as well as thermophysical parameters obtained for the Kara orogen that includes great amounts of syncollisional and postcollisional granites formed due to the collision of the Kara microcontinent and the Siberian craton. Based on geological, geochemical and U–Th–Pb isotope data, the granites have been differentiated into syncollisional and postcollisional intrusions formed 315–282 Ma and 264–248 Ma respectively. Our previously published tectonothermal model [1] concerned the syncollisional formation stage of the Kara orogen at 315–282 Ma, during which the emplacement of anatectic granites took place. In this new study, we focus on the evolution of postcollisional magmatism in the orogen at the Permian–Triassic boundary. The existence of multiple bodies of allochthonous granitoids aged 265–248 Ma in the Kara orogen that predate the extensive eruption of the Siberian traps (~250 Ma) motivates us to reconstruct the thermal state and melting mechanisms of the crust on the “pre-plume” stage. To solve this problem, numerical modeling of the thermal, tectonic and magmatic evolution of the Kara orogen’s crust is used alongside geochemical and isotope data reflecting the magmatic sources of the granitoids.