Abstract:

The Sankuanggou Fe-Cu deposit is an important skarn deposit in the northern Great Hinggan Range. This study investigates the genesis of garnet and its implications for the mineralization process using LA-ICP-MS U-Pb chronology, as well as the major and trace element analyses of garnet conducted by electron probe microanalysis (EPMA) and LA-ICP-MS. The U-Pb dating of garnet yields a weighted mean 206Pb/238U age of (177.1±0.6) Ma, implying that  Sankuanggou skarn Fe-Cu despoit formed during the Early Jurassic in a paleo-Pacific subduction environment. Garnets are predominantly andradite, with minor grossular and uvarovite components. Trace element geochemistry shows depletion in large-ion lithophile elements (such as Rb, Ba and Sr), and enrichment in high field strength elements (such as Th, U, Nb and Ce). Chondrite-normalized rare earth element (REE) patterns are strongly right-inclined, characterized by enrichment in light REEs, depletion in heavy REEs, and positive Eu and Ce anomalies. These features provide insights into the fluid conditions during the early mineralization stage, suggesting that the garnet formed in an acidic and weakly oxidized environment.

Key words: chronology, elemental geochemistry, garnet, skarn,  , Sankuanggou Fe-Cu deposit, northern Great Hinggan Range