致矿侵入体的识别标志——以新疆阿尔夏提矽卡岩型铁铜矿床为例

Identification symbols of causing intrusions: For an example of Aerxiati iron-copper skarn deposit,Xinjiang

致矿侵入体的识别是成矿学研究和资源勘查的关键环节之一,对于许多矿床类型来说也是一个难点。本文以新疆阿尔夏提矽卡岩型铁铜矿床为例,阐述了通过建立五种联系及其地质学、岩石学、矿物学、地球化学和成矿学标志的识别方法,进而提出推木尔特岩基为含矿流体屏蔽层的认识。推木尔特岩基与矽卡岩矿体具有紧密的空间联系,容易被误认为是致矿侵入体。然而,其成岩时间早于成矿时间,仅导致围岩的大理岩化和角岩化,因而不是成矿物质的来源。相反,矿区内分布的闪长质小岩体和各类岩墙不仅与矿体和矽卡岩存在紧密的空间联系,而且岩石中普遍见有造矿矿物与造岩矿物的共结关系,岩体(墙)本身及其围岩也经受了强烈的流体改造,是含矿流体的通道和真正的致矿侵入体。

The identification of causing intrusions is an important part of the metallogenia study and resources exploration,which is also a difficulty for many other types of deposits. The case study,the Aerxiati iron-copper skarn deposit,Xinjiang province,puts forward the understanding that the Tuimuerte batholith is the shielding layer of ore-bearing fluids,through the identification methods that establishing five kinds of contacts and the geology,petrology,mineralogy,geochemistry and metallogeny signs. The close spatial contact between the Tuimuerte batholith and skarn would easily be mistaken-making the batholith as a causing intrusion. However,the diagenetic stage of the batholith is earlier than the mineralization,its enplacement causes the thermal contact metamorphism of the country rocks,resulting the forming of marble and hornfels,which cannot be the resource of the ore-bearing fluids. In contrast,the small intrusive body in the region（ the diorite intrusion） and the kinds of dykes not only have close spatial contacts with the ore body and the skarn,but also themselves and the country rocks suffers the intense hydrothermal alteration,which make the role that the channel of the ore-bearing fluids and the real causing intrusions.