胶东蓬家夼金矿床稳定同位素地球化学特征研究

THE GEOLOGICAL AND GEOCHEMICAL CHARACTERISTICS OF PENGJIAKUANG GOLD DEPOSIT , SHANDONG PROVINCE

蓬家夼金矿床是胶东地区新近发现的金矿床之一 ,矿体赋存在胶莱盆地东北缘拆离断层带中 ,为区内燕山期火山活动前期 ,大气水和岩浆水的参与下形成的层控蚀变构造角砾岩型金矿床。同位素研究表明 ,蓬家夼金矿的硫、碳来源于矿区围岩 ;部分铅则可能具有地幔成因。成矿流体δ1 8OH2 O为 0 .5 9× 10 - 3 ～ 4.0 3× 10 - 3 ,δDH2 O为 - 89.5× 10 - 3 ～- 97.9× 10 - 3 ,反映了成矿流体由大气水和岩浆水混合组成的特点。成矿时代在 90 Ma～12 0 Ma之间。

Pengjiakuang gold deposit in Jiaodong gold metallogenic province is a stratabound gold deposit.It is different from traditional gold deposit,such as Jiaojia type gold deposits and Linglong type gold deposit in Jiaodong Block . It occurs in a detached fault separated conglomerate of Early Cretaceous Laiyang Formation and metamorphic complex of Lower Proterozoic Jingshan Group on the margin of Jiaolai Basin , and was formed before Yanshan volcanic period.Isotope geochemical studies show that the sulfur isotope comes from metamorphic complex of Lower Proterozoic Jingshan Group , carbon isotope comes from the marble in Jingshan Group , while a part of lead comes from the mantle . According to the data of hydrogen , oxygen isotopic compositions (δ 18 O H 2O =0.59‰~4.03‰,δD H 2O =-89.5‰^-97.9‰ ) , the conclusion can be reached that the ore forming fluid of Pengjiakuang gold deposit was a kind of mixed hydrothermal solution which was mainly composed of meteoric water and magmatic water .