Metallogenic Model Of The Zhengguang Gold Deposit In Heilongjiang Province

Zhengguang is an important epithermal gold deposit of the Duobaoshan deposits cluster in Greater Xing’an Mountains. The Au reserves are over 30 t and grade is 3.49 g/t. Researches of it is less. This article do some work about mineragraphy, geochemistry, isotope and geochronology, and establish metallogenic model. Major result as followed:(1) Gold minerals are mainly electrum and Au-rich hessite, which are often precipitate in the fracture of pyrites or between quartz and galena. Gold minerals, chalcopyrite, sphalerite and galena always deposit intergrowth. And the grade of Cu, Pb and Zn can be utilized.(2) The symbol minerals, adularia and Fe-rich sphalerite, of low sulfidation epithermal deposit have been found. The quartz and calcite are pectination. And the fluid is characteristic by low sulfidation. These show that it’s a low sulfidation epithermal deposit.(3)H-O isotopes(δ18O水=-3.2‰~-1.0‰,δD水=-113.5‰~-119.8‰)indicate a meteoric source for fluid with a little magmatic water.C-O isotopes(δ13CPDB=-4.06‰~-1.60‰,δ18OSMOW=6.30‰~14.65‰)demonstate a magmatic source for C and low-temperature alteration feature.Si-O isotopes(δ30Si=-1.0‰~0.3‰,δ18O石英=10.9‰~13.6‰)show that the Si of quartz is magmatic origin.S isotope(δ34S=-5.4‰~-1.5‰,with anomaly of-12.1‰and-8.9‰)indicate a magmatic source of S.(4) Duobaoshan formation and the Ordovician diorite source from low crust, while the Jurassic diorite from middle-upper crust. Lu-Hf isotopes indicate the Ordovician diorite have a source of mantle(εHf(t)= +11.94~ +15.63), while the Jurassic diorite have a source of crust and with a little mantle materials(εHf(t)=-11.76~-1.00). The REE and trace elements demonstrate the Duobaoshan formation is the main source bed.(5) The Zhengguang gold deposit experience 3 mineralization. The first belong to the Duobaoshan porphyry systems(460 Ma~480 Ma); The second is caused by the subduction of Mongol-Okhotsk ocean and Pacific plate(184.6±2.6 Ma); The third is caused by lithospheric delamination followed the closure of Mongol-Okhotsk ocean(150.67±0.77 Ma).