玲珑金矿田48号矿脉蚀变钾长石稳定结构态温度估算及其找矿意义

胶东大开头金矿区位于玲珑断裂和破头青断裂夹持区。48号脉位于玲珑金矿田大开头矿区的西南侧,金矿床为石英脉型—蚀变岩型,围岩有二长花岗岩、钾化花岗岩、绢英岩化花岗岩、绢英岩、黄铁绢英岩、煌斑岩等。本文以玲珑金矿田大开头矿区48号脉矿体两侧钾化花岗岩中钾长石为研究对象,通过X射线粉晶衍射、电子探针等方法研究钾长石晶体结构态及其类别、形成温度与稳定结构态温度,研究结果表明:①48号脉矿体中钾长石应为最大微斜长石;②矿脉两侧钾化蚀变时的温度为410℃~470℃,稳定结构态温度为244℃~274.6℃;③钾长石形成稳定结构态的热液温度环境有利于金的沉淀富集,该类钾长石是深部找矿的良好标志。

Temperature estimation of stable structural state of altered potassic feldspar in No.48 ore vein of Linglong gold ore field and its prospecting significance

Dakaitou mining area is located in the area held by Linglong fracture and Potouqing fracture.The No.48 vein is located in the southwest side of Dakaitou ore area in Linglong ore field.The ore is of quartz vein-altered rock type.The wall rocks of the ore body are monzonitic granite,potassic granite,beresitized granite,beresite,pyriteberesite,lamprophyre,etc.This paper deals with the potassic feldspar in potassic granite on both sides of No.48 vein body.Through X-ray powder diffraction and electron probe analysis and calculation,it is considered that(1)the potassic feldspar in this ore body should be the maximum microcline;(2)the temperature of potassic alteration on both sides of the vein should be between 410 and 470℃,and the temperature range of stable structural state is between 244 and 274.6℃;(3)The hydrothermal temperature environment in which potassic feldspar forms in stable structure is conducive to the precipitation and enrichment of gold.Potassic feldspar is a good prospecting mark of this type of gold deposit.