Zircon SHRIMP U-Pb dating for island arc volcanic rock of Fangniugou area in Yitong region of Jilin Province

Polymetallic iron ore sulphate deposits of marine volcanic rock have been developed in the Fangniugou area, Jilin Province, China, but the division of volcanic ore-bearing strata has not been specifically elucidated and there is disagreement about the division. The sampling and SHRIMP U-Pb zircon dating of volcanic rock for Daheishan in the Fangniugou area and the northeast slope of the Duanjiadian were described. The volcanic rock formation period and recorded the volcanic events in the Daheishan mountains were systematically researched. Two samples of high-precision U-Pb zircon dating were used to represent the volcanic rock fomation period of the Late Silurian. The measured data reflect that multiple volcanic activities occurred during the Middle Silurian, Early Silurian, Middle Ordovician and Silurian, and Late Ordovician, probably matching volcanic events in the Songnan Basin identified from zircon dating. At the same time, it is confirmed that a controversial “conglomerate of Daheishan” did in fact develop in the Late Silurian, and those sections of both the Dazigou and Xinlitun-Taoshan with graptolite had been reversed.