Metallogenic Regularity of Yanshanian Intermediate-acid Small Intrusions in East Qinling.

Geological characteristics of porphyry-skarn Mo deposits, which were related to intermediate-acid small intrusions in Mo ore belt of East Qinling, were summarized; spatiotemporal distrihution, metallogenic characteristics and ore-forming material sources were discussed, and then the metallogenic regularity was discovered; compositions of major element and trace element and ore-forming age for large hatholith and intermediate-acid small intrusions were analyzed, and the relationships of them were discussed. The results show that the oreforming ages of East Qinling Mo deposits related to magmatism can he divided into two stages, 141-156 Ma and 110-138 Ma; the deposits forming in the former stage are mainly distributed in the south of East Qinling, and those in the latter stage are mainly distributed in the north; the ore-forming ages become younger gradually from west to east and from south to north; Mo deposits distribute in groups or belts, and concentrate on sections with equal distance; the combination of mineralization elements is controlled by the magmatic evolution series, and the more acid magtna is, the better Mo mineralization is; data of trace element and isotope indicate that the metallogenic materials are mainly from the crust, and the effect of mantle are not obvious; a close genetic relationship is present between large batholith and small intrusions from the comagmatic evolution, and large batholith provides heat and material substance for small intrusions, so that there are large orebodies hosted in small intrusions. [ABSTRACT FROM AUTHOR]