In situ U-Pb Dating of Calcite from the South China Antimony Metallogenic Belt.

ABSTRACT

Accurately determining the age of hydrothermal ore deposits is difficult, because of lack of suitable mineral chronometers and techniques. Here we present the first LA-MC-ICPMS U-Pb age of carbonates from hydrothermal Sb deposits. Three stages of hydrothermal carbonates from the giant South China Sb metallogenic belt were identified (1) pre-ore dolomite (Dol-I), (2) syn-ore calcite (Cal-II), and (3) post-ore calcite (Cal-III). The U and Pb isotopic data show that Cal-II yielded a lower intercept age of 115.3 ± 1.5 Ma (MSWD = 2.0), suggesting a Sb mineralization that corresponds to an extension event occurred during the early Cretaceous in South China. Although Cal-III yielded an age of 60.0 ± 0.9 Ma (MSWD = 1.5), indicating a potential tectonothermal event occurred in this belt during the early Cenozoic. Hence, in situ U-Pb dating of calcite offers a new way to determine the age of hydrothermal ore deposits.