北山地区金矿类型、成矿规律和找矿方向

北山地区金矿床分布广，主要类型有韧性剪切带型，岩浆热液型和海相火山岩型，成矿物质主要来源于基底变质岩，华力西期中酸性侵入岩和石炭系海相火山岩和次火山岩。除基底变质岩和石炭系火山岩外，其他层位赋矿选择性不明显。成矿流体以岩浆来源为主，但韧性剪切带型金矿床成矿流体来源于岩浆热液和动力变质热液，构造控矿作用研究表明，区域大地构造控制成矿岩系分区，二级构造控制成矿带和成矿岩体的分布，主要赋矿构造形式有韧性剪切带，低角度推覆构造和岩体构造裂隙，金矿床的成矿时代以晚古生代为主，金矿有利找矿远景区是小西弓外围地区、白墩子－石板墩地区、金窝子－照壁山地区、拾金坡－南金滩地区，马庄山－南金山外围地区和古堡泉－老金厂地区。

GENETIC TYPE CHARACTERISTICS AND EXPLORATION OF GOLD DEPOSIT IN BEISHAN AREA, GANSU PROVINCE

There occurs a lot of gold deposits which belong to three genetic types:ductile shear zone-type,magmatic-hydrothermal type and marine-volcanic type.Source materials of gold deposits in the area are derived mainly from the metamorphic rocks,Variscan intermediate-acid intrusive rock,and marine volcanic rocks and sub-volcanic rocks of Carboniferous system.Except the metamorphic rocks and volcanic rocks of Carboniferous system,there is little selectivity of stratigraphic time for gold deposit to occur.Ore fluid of magmatic-hydrothermal type and marine-volcanic type gold deposits is drawn mainly from magmatic water,but one of ductile shear zone-type from magmatic water and dynamic metamorphic hydrothermal solution.The study of structure controls of gold deposits shows that tectonics and regional structure control the distribution of ore bearing rock series,secondary structure controls the distribution of ore forming rock mass and mineralization belts.The ore-hosting structures are ductile shear zone,low angle faults,and fractures in the magmatitic mass.And most of gold deposit in the area fromed mainly in late Paleozoic era.The prospective places for gold deposit are Xiaoxigong and its peripheral area,Baidunzi Shibandun area,Jinwozi Zhaobishan area,Shijinpo -Nanjintan area,Mazhuangshan -Nanjinshan area and Gubaiquan Laojinchang area.