摘要
孔辛头铜钼矿床产于胶东地区伟德山超单元院格庄二长花岗岩与荆山群大理岩接触带形成的夕卡岩中,主矿体呈透镜状、囊状、脉状产出,受岩体内部裂隙构造控制。分别采用电感耦合等离子体质谱、热表面电离质谱Re-Os同位素测试技术对其中的辉钼矿、黄铜矿、磁铁矿进行了研究。结果显示,辉钼矿Re-Os等时线年龄为117±1 Ma,黄铜矿Re-Os等时线年龄为118.4±3.2 Ma,与区域上尚家庄钼矿床、冷家钼矿床成矿时代一致,几个矿床成因均与伟德山超单元有关,表明了胶东地区存在燕山晚期的钼矿化事件。而磁铁矿Re-Os封闭性较差,无法得到年龄。黄铜矿初始^(187)Os/^(188)Os值为0.32±0.17,表明了孔辛头铜钼矿床金属成矿物质为壳幔混合来源,形成于早白垩世太平洋板块向亚欧大陆俯冲而成的弧后拉张背景之下。
Kongxintou copper-molybdenum depositproduced from skarn which formed via contact metasomatism between Jiaodong Weideshan superunit Yuangezhuang monzonitic granite and Jingshan Group marble. The main orebody occur as lenticular, cystic and veined controlled by fissure structure within the rock body. This research studied the molybdenite, chaleopyrite and magnetite adopting inductively coupled plasma mass spectrometry and thermal respectively. The results show that lomzatlon mass spectrometry testing Re-Os isotope technology the Re-Os isochron age of molybdenite is 117~ 1 Ma, chalcopyrite is 118-t-3.4 Ma, which consistent with Shangjiazhuang molybdenum deposit and Lengjia molybdenum deposit. Those ore genesis relate to Weideshan superunit, indicating the presence of the Late Yanshan molybdenum mineralization events in Jiaodong. However the magnetite can not get Re-Os isochron age due to poor sealing property. Chalcopyrite Os isotopic initial value Osi= 0.3 ± 0. 02, shows the Kongxintou copper-molybdenum deposit into a source of crust mantle mixed, formed from the back-arc extension of Pacific plate subduction to the Eurasian continental in the early Cretaceous.
出处
《地质学报》
EI
CAS
CSCD
北大核心
2016年第2期240-249,共10页
Acta Geologica Sinica
基金
自然科学基金项目(41203037)
国土资源地质大调查项目(12120113015500)资助的成果
