Zircon U-Pb dating of the Luodian nephrite deposit and its adjacent granites in Guizhou Province

• 1、Guizhou Institute of Geological Survey, Guiyang, Guizhou 550081, China

Abstract：Nephrite has a fine structure and very few accessory minerals, and generally does not possess the condition of zircon U-Pb dating. On the other hand, the content of K, Rb and Sr in nephrite is very low, and it is difficult to use the whole-rock K-Ar method, Ar-Ar method and Rb-Sr isochronal dating method, so the dating of nephrite has always been a difficult problem in ore deposit study. For a long time, metallogenic age of nephrite ore mainly depends on the general inference of the field geological relationship, which may sometimes lead to significant wrong conclusions. In this study, hydrothermal zircon was successfully selected from Luodian nephrite, LA-ICP-MS zircon U-Pb age was 86.9±2.0Ma, which was consistent with the age of the granite dike (86.0±0.6Ma) near the ore body within the error range, indicating that the mineZircon U-Pb dating of the Luodian nephrite deposit and its adjacent granites in Guizhou Provinceralization of Luodian nephrite is related to the intrusion of granitic magma in this period, thereby, the metallogenic age of Luodian nephrite is limited to 86 Ma, which changes the viewpoint that Luodian nephrite was formed by contact metasomatism of Late Hercynian basic magma.

Keywords： Zircon U-Pb dating Luodian nephrite Granite dike Guizhou Province