It was previously considered that all of the Pb-Zn deposits in the Xicheng orefield belong to Devonian hydrothermal-sedimentary deposits or their reworked ones. Study proves that the host strata, besides the Devonian,...It was previously considered that all of the Pb-Zn deposits in the Xicheng orefield belong to Devonian hydrothermal-sedimentary deposits or their reworked ones. Study proves that the host strata, besides the Devonian, include the Palaeoproterozoic. The super-large Changba-Lijiagou Pb-Zn deposit occurs in the Palaeoproterozoic strata. The deposits in this district are not hydrothermal-sedimentary deposits or their reworked ones, but Yanshanian-Himalayan epigenetic hydrothermal deposits. The modes of occurrence, sizes and positions of all the deposits in the Xicheng orefield are completely controlled by the choula (draw)-thrust sheet Therefore the previous grounds for the model of the Qinling-type Pb-Zn deposits cannot hold good. The authors propose that the Changba-type and Bijiashan-type Pb-Zn deposits be used to represent two mineral deposit models with different characteristics in the Xicheng orefield.展开更多
基金This study was supported by the National Natural Science Foundation of China grant 49272136, the State Science and Technology Commission Project 96-914-01-04 and the Ministry of Geology and Mineral Resources Shaanxi-Gansu-Sichuan Project 95-02-002-01.
文摘It was previously considered that all of the Pb-Zn deposits in the Xicheng orefield belong to Devonian hydrothermal-sedimentary deposits or their reworked ones. Study proves that the host strata, besides the Devonian, include the Palaeoproterozoic. The super-large Changba-Lijiagou Pb-Zn deposit occurs in the Palaeoproterozoic strata. The deposits in this district are not hydrothermal-sedimentary deposits or their reworked ones, but Yanshanian-Himalayan epigenetic hydrothermal deposits. The modes of occurrence, sizes and positions of all the deposits in the Xicheng orefield are completely controlled by the choula (draw)-thrust sheet Therefore the previous grounds for the model of the Qinling-type Pb-Zn deposits cannot hold good. The authors propose that the Changba-type and Bijiashan-type Pb-Zn deposits be used to represent two mineral deposit models with different characteristics in the Xicheng orefield.
