Mesozoic high-Sr, low-Y and low-Sr, low-Y types granitoids in the northern Hebei province: Geochemistry and petrogenesis and its relation to mineralization of gold deposits
冀北中生代高Sr低Y和低Sr低Y型花岗岩：地球化学、成因及其与成矿作用的关系

North Hebei is one of important gold-producing areas in China. Most gold deposits in the northern Hebei are related to Mesozoic intermediate-acid intrusions, although they are different in genetic types. Based on the studies of this paper, these intrusions can proximately be divided into two types: a high-Sr and low-Y type and a low-Sr and Y type. The first type of intrusions has the geochemical features of adakite, and therefore it is inferred to be a possible product of partial melting of the over-thickened continental lower crust with a residual phase of eclogite or amphibole eclogite. The second type, ontke one hand, is different from the first one by its low Sr and Al contents and obviously negative Eu anomaly; on the other hand, it is similar to adakite by its low Y and HREE contents. Therefore, it is suggested that the low-Sr, low-Y type intrusions were generated by partial melting of relatively thick lower crust under high pressure granulite facies conditions with plagioclase to be the dominant residual phase. Considering that the gold deposits are spatio-temporally associated with the two types of intrusions and previous S, Pb, H, O and C isotopic data of the gold deposits in the North Hebei, which indicate that the mineralizing fluids and/or materials are most likely derived from mantle-lower crustal source, we concluded that the gold deposits have genetic relationships with high-Sr, low-Y type and low-Sr, low-Y type intrusions. This will be helpful in understanding the genesis and exploring mineral deposits in the northern Hebei Province.