云南澜沧地区南角河银多金属矿床的地质特征及成因

Geological characteristics and genesis of the Nanjiaohe Ag-polymetallic deposit in the Lancang area,Yunnan,China

南角河银多金属矿是在地质调查过程中发现并评价的一个具有大型找矿远景的矿床。矿床产于临沧-勐海复式花岗岩基南段西侧与新元古界澜沧群变质岩的接触断裂破碎带(白章断裂)中,矿体呈脉状,形态单一。同位素及成矿流体分析结果表明,成矿物质主要来源于花岗岩和澜沧群地层,成矿流体以大气降水下渗加热上升回返并混合少量岩浆热液为特征,以花岗岩和澜沧群变质岩为矿源层,以断裂破碎带为赋存空间,为具有明显垂向分带特征的低温热液矿床。

The Nanjiaohe Ag-polymetallic deposit was found and evaluated during geological survey and has good ore prospects. The deposit is located in a contact fractured zone （Baizhang fault） between the southwestern side of the southern segment of the Lincang-Menghai compound granite batholith and metamorphic rocks of the Lancang Group. The orebodies occur only as veins. Isotope and ore fluid analysis show that the ore materials were mairfly derived from granite and metamorphic rocks of the Lancang Group and that the ore fluids originated by infiltration of meteoric water and then its rise and mixing with small amount of magmatic hydrothermal fluids. The source of ores may be granite and metamorphic rocks of the Lancang Group. The orebodies are hosted in a fractured zone and have pronounced vertical zoning. So, based on these characteristics, the Nanjiaohe Ag-polymetallic deposit is an epithermal one.