Effects of accessory mineral inclusions and signal acquisition time on zircon U-Pb dating and trace element analysis results
In-situ zircon micro-area U-Pb dating and trace element analysis have become routine techniques in Earth sciences.However,the interpretation of zircon micro-area analysis results is influenced by various factors,including the selection of analysis points,instrument stability,and signal correction.Quantitatively understanding how these factors affect zircon micro-area analysis results is a critical prerequisite for accurately interpreting the geological significance of such data.This study focuses on zircons from the Late Triassic monzogranite porphyry intrusion in the Yemaquan iron-polymetallic deposit in Qinghai Province.LA-ICP-MS zircon in-situ U-Pb dating and trace element analysis were performed to evaluate the effects of accessory mineral inclusions and signal acquisition time on zircon micro-area analysis results.The findings indicate that although shorter signal acquisition times lead to larger errors in U-Pb dating,they do not significantly affect U-Pb ages or trace element analysis results.A comparison of analysis points with and without mineral inclusions shows that the presence of mineral inclusions also does not significantly interfere with dating results.However,if the selected zircon analysis location contains accessory mineral inclusions(e.g.,apatite),the resulting data may display a false"light rare earth element enrichment"signature.This can lead to misinterpretations,such as incorrectly inferring magmatic oxygen fugacity characteristics.Therefore,it is crucial to first identify whether accessory mineral inclusions are present at the analysis location before conducting zircon micro-area analysis.Additionally,zircon data contaminated by mineral inclusions must be excluded prior to interpreting the geological significance of zircon trace element data.
LA-ICP-MSzirconU-Pb datingaccessory mineral inclusionssignal acquisition time
万方数据
维普
