Metallogenica Age of Mississippi Valley Type Pb-Zn Deposit in Fankou, Guangdong: Evidence from SHRIMP U-Pb Zircon Dating of Diabase
详细信息
- 责任者：Zhu Xinyou (Beijing Institute of Geology and Mineral Resources ; Beijing 100012 ; China) ; Wang Jingbin
- 刊名：Acta Geologica Sinica
- 出版年：2013
- 卷期：87(2)
- 关键词：铅锌矿床 ; lead-zinc deposit ; SHRIMP定年 ; SHRIMP dating ; 广东 ; Guangdong
- 页码：p.167-177
- 图表：illus., 2 tables, 39 refs.
- 分类号：1001
- issnNo：ISSN0001-5717
- isbnNo：CN11-1951/P
摘要
The Fankou MVT-type lead-zinc deposit located in northern Guangdong province is one of the largest Zn-Pb deposits in China, with a proven reserves of up to 10 million tons. It occurs in dolomitized limestone in the upper part of the Devonian transgressive sequence as irregular lead-zince orebodies, which are controlled by the NNE-trending faults and cut by NWW or NNW-trending diabase veins. Diabases close to ore bodies are carbonatized and clayizized. Diabases cut through both Zn-Pb ore bodies and dissemiated Zn-Pb veinlets, indicating the diabase formed later than mineralization. The fact that the ore-forming continued a long term and the diabase intruded at the late period of the ore-forming support that the diabase and the lead-zinc ore formed at almost the same period. The SHRIMP U-Pb zircon ages of the diabase are 2213～957 Ma, 341～216 Ma, 138～127 Ma and 122～90 Ma. The first two groups of the ages represent the captured zircons. Comparing the geological characteristic and evolution, ages of uranium deposit and diabases, we can infer that the deposit formed at 122～90Ma (Cretaceous Period) in the extensional tectonic environment corresponding to the formation of large scale red bed basin. Thus, the ore-forming model of the Fankou deposit is established as fallows: since early Cretaceous, red bed basins started to develop within the South China area due to uplift of Wuyi mountains which held back the moisture air from Pacific ocean, with the lead-zinc deposits distributed mainly around the margin of the red bed basins, and mixing of brines from the red bed basins and the sulfur-rich reductive brines from the hydrocarbon layer resulted in the formation of the Zn-Pb deposits.