Geochronology, mineralogy, crystallization process and tectonic implications of the Shuangyashan monzogabbro in eastern Heilongjiang Province
黑龙江省东部双鸭山二长辉长岩的年代学、矿物学、结晶过程及其地质意义

The Shuangyashan monzogabbro occurs in the Lower Cretaceous coal-bearing strata in the Shuangyashan basin, eastern Heilongjiang Province, Northeast China. In the monzogabbro, olivine, plagioclase, clinopyroxene and ilmenite subsequently crystallized from magma, whereas biotite and minute orthopyroxene resulted from the reaction of evolved magma with the crystallized ilmenite and olivine, respectively. Finally, the residue magma crystallized as anhedral K-feldspar and enclosed all already crystallized minerals, showing the poikilitic texture. Thermodynamic simulation for crystallization process of the Shuangyashan monzogabbro shows the results are generally consistent with the petrographic observation. Biotite K-Ar and SHRIMP zircon U-Pb dating consistently yielded an early Late Cretaceous age of 98Ma for the monzogabbro. In the Late Cretaceous, eastern Northeast China, Khingan-Okhotsk of Far East Russian, and Southeast Japan together were in an active continental margin setting. The early Late Cretaceous subduction-related magmatism may be widely distributed in eastern Northeast China.