SHRIMP zircon U-Pb ages of Kalatongke No. 1 and Huangshandong Cu-Ni-bearing mafic-ultramafic complexes, North Xinjiang, and geological implications

Abstract

The SHRIMP zircon U-Pb dating was carried out and yielded 287±5 Ma (MSWD = 0.34) and 274±3 Ma (MSWD = 1.35) for the Kalatongke No. 1 and Huangshandong Cu-Ni-bearing mafic-ultramafic complexes. These ages are much more precise than pre-existing rock-mineral Rb-Sr, Sm-Nd and Re-Os isochron ages for the two complexes and constrain the timing of not only the complexes but also the magmatic Cu-Ni sulfide deposits more reliably. It is necessary to carefully reevaluate the previous chronological data for the complexes. The Cu-Ni-bearing mafic-ultramafic complexes have the ages similar to those of postcollisional A-type granites in the same area, implying that they could be related to the delamination of lithospheric mantle and upwelling and partial melting of asthenospheric mantle in postcollisional setting. Therefore, the Cu-Ni-bearing mafic-ultramafic complexes are a direct indicator of vertical growth of the continental crustal in the Central Asian Orogenic Belt.