赤峰—朝阳地区金矿床流体包裹体特征及成因

Characteristicsof fluid inclusions and genesis of gold deposits in Chifeng to Chaoyang area,northeastern China

区内两大类金矿流体包裹体的研究表明 ,Ⅰ类金矿以次生包裹体为主 ,盐度为 3 5 %～4 0 % ,均一温度为 160～ 2 2 0℃ ,压力为 4 0 0× 10 5～ 70 0× 10 5Pa ,CO2 摩尔百分数小于 5 5 ,K+ /Na+ <1;Ⅱ类金矿以原生和假次生包裹体为主 ,盐度为 5 %～ 7% ,均一温度为 2 5 0～ 35 0℃ ,压力为 4 0 0× 10 5～ 80 0× 10 5Pa ,CO2 摩尔百分数一般小于 6,K+ /Na+ >1。Ⅰ类金矿液起源于太古宙变质岩重熔岩浆 ,金沉淀和矿液温度的下降有关 ;Ⅱ类金矿液起源于同熔花岗岩浆 。

Study on the fluid inclusions of two types of gold deposits in the region shows that the typeⅠgold deposits are predominated by the secondary fluid inclusions,the salinity is 3 5%～4 0%,the homogenization tempreture is 160～220 ℃,the pressure is 400×10 5 ～700×10 5 Pa,and CO 2<5 5 mol%,K +/Na +<1;and the type Ⅱ gold deposits are predominated by the primary or pseudosecondary fluid inclusions,the salinity is 5%～7%,the homogenization tempreture is 250～350 ℃,the pressure is 400×10 5 ～800×10 5 Pa,CO 2<6 mol%,and K +/Na +>1.The fluid in typeⅠgold deposits originated from remelting magma of the Archean metamophic rock,the precipitation of gold is related to the decline of fluid tempreture;whereas the fluid in type Ⅱ gold deposits originated from the syntectic granite magma,the precipitation of gold is related to the middle late stage boiling of fluid and sulfurization of wall rocks.