GEOCHEMISTRY ON GENESIS OF XIAYINGFANG GRANITE—PORPHYRY IN NORTHEASTERN HEBEI,CHINA

Xiayingfang rock body occurs in Xinglong-Kuancheng arcuate folded area of Yanshan platform fold zone of eastern Yinshan-Yanshan east-west tectonic zone and is a small Yanshan-period composite stock that outcrops about 0.65 km^2. This permissive rock-body is closely controlled by the hinge belt of a regional asymmetric fold.The magma uptruded along the decollement plane between the layers and was eventually located in the pitching end of the fold due to the effect of the EW and NNE faults. The pitching direction of the stock is consistent with that of the anticlinal hinge, that is, it pitches towards SWW with 600--83~ plunging angle. Its wallrock strata includes Archaeozoic, Middle Proterozoic and Mesozoic erathems. The major rocktypes are adamellite-porphyry, moyrite-porphyry and alkali-feldspar granite-porphyry as well as rhyolite-porphyry and crypoexplosive breccia. Potassium feldspar is of higher order degree and fall into microcline-orthoclase series; plagioclase An=25-35; biotite is magnesian;