In situ U-Pb isotopic dating method on titanite, and application to determine REE-Fe-Cu mineralization age of the Sin Quyen deposit, Lao Cai province

Tóm tắt

Titanite (CaTiSiO5) is an important common accessory mineral in hydrothermal deposits, with appreciable amounts of U and Th incorporated into their structures for age dating. Titanite crystals are usually larger than zircon and monazite and may have zoning in texture and geochemistry which represent different parageneses likely related to multiple hydrothermal or mineralization events. In line with the development of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) that has high sensitivity and spatial resolution, in-situ U-Pb isotopic dating method on titanite has become a powerful tool to investigate the ages of different zones from a mineral. Titanite typically accommodates a significant amount of Rare Earth Elements (REEs) and High Field Strength Elements (HFSEs) and the titanite generated from different origins exhibits distinct trace element geochemistry. Therefore, the trace element geochemistry of titanite can serve as an indicator of its formation environment. Titanite occurred in different mineralization stages of the Sin Quyen deposit, making it a suitable mineral for investigating the timing of mineralization. In this paper, we present the U-Pb age of titanite from different stages of the Sin Quyen deposit used to constrain the timing and origin of such events. The hydrothermal titanites are dated by in situ LA-ICP-MS technique and have U-Pb ages of 873±12 Ma and 844±12 Ma which indicate two mineralization/hydrothermal events at the same time, respectively. These ages from the Sin Quyen deposit are well correlated with regional tectono-thermal events during the long-lived Neoproterozoic subduction in the western Yangtze Block