地质学报2017，Vol.91Issue(4)：748-761,14.
南秦岭石泉北部将军河地区中酸性岩脉锆石U-Pb年代学及其构造意义
Zircon U-Pb Geochronology of Intermediate-Felsic Dykes from the Jiangjunhe Area in Northern Shiquan, South Qinling Mountains and Its Geological Significance
摘要
Abstract
Numerous intermediate-felsic dykes are present in the northern part of Shiquan County in the South Qinling region.Most of the dykes have a structural contact relation with strata.But the relationship between formation age and gold mineralization in this area has been debated.In this study,a total of 13 rock samples were collected from several intermediate-felsic dykes in the northern part of Shiquan County.Field observation and indoor identification suggest that these dykes belong to diorite.The major elements analysis shows that diorite has a SiO2 content of 53.19％～68.48％,with A/CNK value of 0.67～1.28 and Rittman index (σ) of 1.4 ～2.93.The REE compositions indicate that intermediate-felsic dykes have a lower content of total REE (∑REE=(44.54～253.23) × 10-6) and are characterized by significant light REE enrichments relative to heavy REE (HREE/LREE=6.15～14.87,with (La/Yb)N =5.97～38.67) and weak negative Eu anomaly(δEu=0.68～0.88).Trace element analysis shows an obvious enrichment of lithophile elements (such as Ba,K,Sr),and depletion of high field strength elements (such as HREE,Ti,P,Th),indicating that these dykes were the products of lower crust remelting induced by the oceanic lithosphere subduction.Single zircon U-Pb dating age (771.9 ± 3.4 Ma) of diorite dykes is synchronous to that of the complex in southern Hanzhong and the Neopaleozoic magmatic activity at Fenghuangshan Mts north of Ankang,indicating a tectonic setting of regional extension breakup.Field geological mapping indicates that the Neoproterozoic dikes in the Jiangjunhe area has no direct genetic relation with the formation of gold deposits.关键词
南秦岭石泉北部/中酸性岩脉/闪长岩/锆石U-Pb年龄/构造背景Key words
Northern Shiquan in South Qinling Mountains/intermediate-felsic dykes/diorite/zircon U-Pb age/tectonic background引用本文复制引用
段少帅,焦建刚,罗德智,黄喜峰,王硕,陈炳龙..南秦岭石泉北部将军河地区中酸性岩脉锆石U-Pb年代学及其构造意义[J].地质学报,2017,91(4):748-761,14.基金项目
本文为国家自然科学基金项目(41672064,41372101)和公益性行业科研专项(200911007,201011058)联合资助. （41672064,41372101）
