Lead in K－Feldspar and Its Relations to Rb Metallogenesis

• Published in: Chinese journal of geochemistry Vol. 22; no. 2; pp. 107 - 115
• Main Author: 张乾 刘志浩 裘愉卓 高计元 王一先
• Format: Journal Article
• Language: English
• Published: 2003
• Subjects: 地球化学; 流体相; 金属成矿作用; 钾长石; 铅矿床
• ISSN: 1000-9426; 1993-0364

In intermediate-acid magmatic rocks,alkaline magmatic rocks,gneisses and migmatitic rocks K-feldspar is a rock-forming rock in which the contents of Pb are highest,just 2-10 times those of the whole rock,3-16 times those of mica minerals and 6-32 times those of quartz.The lowest contents of K-feldspar are recognized in Early Proterozoic and Achaean rocks,with Pb in the K-feldspar accounting for less than 10% of that in the whole rock;in post Middle Proterozoic alkaine magmatic rocks,K-feldspar-rich granites and metamorphic rocks the contents of K-feldspar tend to increase,with the proportion granites and metamorphic rocks the contents of K-feldspar tend to increase,with the proportion of Pb over that in the whole rock being obviously increased.In the alkaline rocks in which K-feldspar accounts for 50%-70% of the total in the whole rock,the contents of Pb in K-feldspar account approximately for 70%-95% of the total lead in the whole rock.Being accessible to hydrothermal alteration in the late periods,K-feldspar was conversed to sericite,calcite,quartz,etc.In the process of such conversion the lead would be leached out and then find its way into fluid phase.This kind of trans-formation can provide sufficient ore-forming material for later Pb metallogenesis.