Geochronology of Two Mafic Intrusions in Funing, Yunnan: Implications for Its Relationships with Carlin-like Gold Mineralization

Abstract

The relationship between mafic intrusion and gold deposits has always received substantial attention. Based on the petrography, mineralogy, and chronology of two mafic intrusion suites exposed in the Funing area, we found that the mafic intrusion suites have closely relationship with gold mineralization. The 255±4.9-Ma U-Pb age of the early mafic intrusion suite is much older than the 218.9±6.4-Ma (MSWD=1.2) U-Pb age of the late mafic intrusion suite. Based on previous studies on former gold mines in the area, it is believed that early mafic intrusion suite appears to have contributed to the early hydrothermal enrichment of gold deposits through the action of water-rock, together with atmospheric precipitation and stratigraphic water. Due to favorable structural conditions during the Indosinian tectonic period, the late basic rock not only extracted metallogenic materials from the stratum but also acted as an important heat source for the metallogenic fluid circulation and mineralization, together with superposed mineralization of frequent tectonic activities on early deposits, finally forming into ore deposits in favorable structures. Therefore, we believe that the mafic intrusion suite in the late period of the region are closely related to the gold mineralization in the region, and it can be used as a prospecting mark for gold deposits in the area.