论文部分内容阅读
This study presents zircon LA-ICP-MS U-Pb geochronology,trace elements characteristics,whole rock geochemistry composition and zircon Hf isotopic data of Shuimowan tonalites in Dengfeng City.The results show that zircons from Shuimowan tonalites have oscillatory growth zoning,relatively high Th/U ratios (0.8-1.7) and upted zircon rare earth elements (REE),indicating that they are magmatic origin.Shuimowan tonalites yield a weighted mean 207pb/206pb age of 2 522 ± 9 Ma,indicating they were formed in the latest Neoarchean.The tonalites are characterized by relatively low SiO2 contents,high MgO and Na2O contents,high REE (∑ REE =322 × 10-6-354 × 10-6),obvious fractionation of REE,enrichment in LREE and feeble negative Eu anomaly (Eu/Eu* =0.97-0.99).The samples are also enriched in large ion lithophile elements and depleted in high field strength elements,with negative Nb,Ta,P and Ti anomalies.The εHf(t) values of zircon grains from Shuimowan tonalites range between 3.5 and 5.3.Combined with regional tectonic evolution,it is suggested that Shuimowan tonalites were derived from partial melting of mantle peridotite metasomatized by the slab-derived felsic melt and formed in the arc magma tectonic setting related to plate subduction.Research on the Neoarchean Shuimowan tonalites provides a constraint for the study of the Pre-Cambrian tectonic evolution in the south margin of North China Craton.