Formation Conditions of the Postcollisional Granites of the Kara Orogen (Northern Taimyr, Central Arctic): Application of 3D Numerical Modeling

Using 3D numerical modeling, we analyze the formation of postcollisional granitoids of the Kara orogen in Northern Taimyr under conditions of elevated heat flow due to the orogen’s breakup prior to its mantle plume episode (280–250 Ma). The initial geometry of the model area, the boundary conditions and physical properties for the crust and the mantle have been selected to reflect the structure of the crust in the junction zone of the Kara, Central Taimyr, and Siberian blocks. Comparing 2D and 3D modeling results with identical parameters and physical properties defined by the Rayleigh number shows that 3D modeling yields a more realistic and correct description of relevant magmatic processes. At the base of the modeled Earth crust an area of melting at a depth of ~46–50 km appears, possibly with slight input of mantle component, which induces magma uplift and the formation of closely spaced granitoid intrusions. Plutons with diameters 10–20 km were emplaced at depths 14–8 km during 15 million years, which is close to the actual geological position and timing of postcollisional stocks of the Kara orogen.