Discovery of the Late Carboniferous alkali-feldspar granite from the Bulinmiao area in Inner Mongolia and its constraints on the evolution of the Paleo-Asian-Ocean

In this paper, LA-ICP-MS zircon U-Pb dating and geochemical characteristics of the Bulinmiao alkali-feldspar granite pluton located in the northern margin of the Hegenshan ophiolite belt are studied in order to explain its petrogenesis and tectonic significance.The study shows that the zircon U-Pb dating give weighted average age of 304±1 Ma, indicating that it is the product of magmatic activity in the Late Carboniferous.The general characteristics of the granite samples are similar, showing the characteristics of high silicon, rich alkali, rich K, and weak peraluminous.Trace elemental data of these rocks show LILE(Rb, K)enrichment, HFSE(P, Sr, Ti)depletion.Combining with the 10000Ga/Al value, TFeO, Zr contents and zircon saturation temperatures of the sample, the pluton is an aluminous A-type granite and belongs to the high-K calc-alkaline series.The granite was the product of the early stage post-orogenic extension after closure of Hegenshan Ocean.