肖板金矿床构造控矿特征与成因探讨

肖板金矿床赋存于闽中前寒武系变质岩中,属于构造蚀变岩型金矿.控矿构造是在变质岩构造基础上发育起来的蒲洋变质核杂岩构造系统之北西侧的剥离构造——低角度正断层系.低角度断层不仅控制了矿体的形态、产状、规模和分布,其压扭性力学性质决定了交代为主的矿化蚀变类型,而且在成矿过程中也起到地球化学界面作用.硫同位素、铅同位素、氢氧同位素、初始锶比值、稀土元素特征等资料反映出肖板金矿成矿物质主要来源于麻源群变质岩,并有少量岩浆物质的加入,成矿时代为燕山早期.流体包裹体特征显示成矿流体主要来源于岩浆水,并有大气降水的混入,成矿温度190~244℃.结合构造演化和构造控矿特征分析认为肖板金矿床是受低角度正断层(剥离断层)控制的中低温岩浆热液型矿床.

ORIGIN AND STRUCTURAL CONTROLS OF XIAOBAN GOLD DEPOSIT, FUJIAN PROVINCE

Xiaoban gold deposit,as an altered fractured rock type,is situated in central Fujian Provincewhere metamorphic rocks of Middle Proterozoic Mayuan Group are widely distributed The ore controlling structure of the deposit are low angle faults-the detachment faults in the northwest of Puyang metamorphic core complex The low angle faults are important impounding structure Their shape,attitude,scale and distribution control over those of the gold orebodies and the mechanical property over the mineralization alteration type The ore controlling structure also plays an important rule of geochemical interface in course of gold mineralization Information from sulfur, lead and strontium isotopes and REE characteristics shows that the source materials of the deposit were derived mainly from metamorphic rocks and subordinately from magma Isotopic dating made on Rb Sr isochron age of altered mineral from the deposit indicates that the mineralization occurs in early Yanshanian And inclusion study indicates both magmatic and meteoric water sources for the ore fluid Based on these facts in combination with an analysis on regional structural evolution and the role played by structure in controlling ore geneses,a new conclusion can be drawn that Xiaoban gold deposit is a medium low temperature magmatic hydrotermal deposit controlled by lower angle faults(detachment faults)