Seismic refection data collected across central southwestern Guizhou have shed a light on coal measures of upper Permian Longtan Formation as well as Dongwu and Guangxi unconformities in Carlin-type gold deposits. Seismic profiles and regional gravity have also indicated that most Carlin-type gold deposits are controlled by both paleo-uplift and thrust-fold in this area. On the basis of the seismic profile, gold deposits can be divided into two types, namely thrust-controlled and thrust- accompanied deposits according to the position of the ore deposit in the thrust-fold belt. In thrust-controlled deposits, the thrust characterized by steeply dip angles in the shallow part and smoothly dip angles in the depth detaches into coal measures, tuffs and Dongwu unconformable contact.The fault-related fold always occurs on the hanging wall block. Gold ore bodies occur in the thrust in the veinlike form in the shallow part and in low-angle strata-dissecting shape in the depth. The thrust-accompanied gold ores exist in interlayer-gliding structures caused by high-angle faults in the form of stratoid ore bodies. NW- and NE-trending thrust-fold zones were formed successively during the closure of Paleo-Tethys Ocean in South China in late Indosinian epoch. The thrust-folding was the key factor for mineralization, although the paleo-uplift exerted an initially enrichment of gold. Seismic data also show that there are some thrust-folds similar to the structure zone in places where Carlin-type gold deposits were discovered, which are favorable ore-prospecting areas.%地震勘探资料对黔西南中部卡林型金矿赋存层位上二叠统龙潭组煤系地层、东吴不整合面和广西不整合面显示良好.该地区卡林型金矿主要受古隆起和冲断-褶皱构造的双重控制.根据卡林型金矿在冲断-褶皱构造中的位置,可以将其划分为2类,即断层控制型金矿和断层伴生型金矿.在断层控制型金矿床中,断层“上陡下缓”,为低角度逆冲断层,断层上盘常发育不对称背斜,断层向下在上二叠统龙潭组煤系地层、“大厂层”凝灰岩和东吴运动形成的不整合面间滑脱,并造成地层明显增厚,金矿体产于低角度逆冲断层中,在浅部为脉状矿体,在深部渐变为缓倾斜穿层矿体.断层伴生型金矿床发育于由高角度断层引起的层间滑动带中,呈似层状.印支晚期华南古特提斯洋的相继闭合是形成北西向和北东向两组主要冲断-褶皱构造的构造动力学背景.尽管前期古隆起对卡林型金矿具有初始富集作用,但冲断-褶皱活动则是金矿形成的关键.地震勘探资料揭示,黔西南中部还存在找矿前景较好的冲断-褶皱构造.
展开▼
