柴北缘锡铁山铅锌矿床喷流通道口的识别及其对矿床成因和找矿勘查的指示

Identification of the Spray-vents and Their Implications to the Origin and Ore-prospecting of the Xitieshan Pb-Zn Deposit in Northern Edge of the Qaidam Basin

为进一步探究锡铁山铅锌矿成因和扩大矿山资源量,通过对矿区地质调查以及岩芯观测,在锡铁山矿区发现了一系列独特的沉积构造,如多岩性层的交混揉皱、金属硫化物分层半圆形环带和泄水角砾构造,伴随发育了铁、锰、铅、锌等矿化。在钻孔岩芯中,也发现了一些特殊的条带角砾构造。通过与现代海底“黑烟囱”以及爱尔兰和乌拉尔等地区的古生代“黑烟囱”构造对比,认为这些构造为原生的沉积构造,应属于上涌的成矿物质与海水相互作用的产物,指示了原生喷流通道口的位置。这些原生的喷流通道口呈近似等间距展布,受控于同生沉积断裂和原生的横张断裂。喷流通道口的识别进一步支持了该矿床与海底喷流(VSHMS)有关,同时指示了喷流通道口附近为成矿物质聚集的有利场所,也是寻找富大矿体的主要区域。

In order to further explore the genesis of Xitieshan lead-zinc deposit and expand mine resources,a series of sedimentary structures were discovered based on the geological survey and core observation in the mining area.These structures include the cross-mixed corrugations of the multi-lithological layers,the layered semicircle band of metal sulfide and the sluice-brecciated structures,which accompanied by the mineralization of Fe-Mn and Pb-Zn etc.Similar special sluice-brecciated and banded structures are also identified in the rocks from drilling holes.By comparing with modern and Paleozoic black chimneys in Iceland and the Urals,these structures should be native to sedimentary structures and be the product of ore-forming substances interacting with the seawater at the seafloor,indicating the positions of primary spray-vents which are distributed approximately equally spaced and are controlled by the syn-genetic sedimentary and primary transverse faults.The identification of primary spray-vents further supported that the deposit is a kind of volcanic-sedimentary-hosted massive sulphide(VSHMS)deposit,and suggesting that the area near the spray-vents should be a favorable place for the accumulation of ore-forming materials and therefore be the main area for searching of high-grade ore bodies.