铀矿地质2025，Vol.41Issue(5)：836-852,17.DOI:10.3969/j.issn.1000-0658.2025.41.058
林西新城子盆地吉布吐地段花岗斑岩成因和地质意义:年代学、地球化学和同位素制约
Genesis and Geological Significance of Granite Porphyry in Jibutu Sector of Xinchengzi Basin,Linxi:Constraints from Chronology,Geochemistry and Isotopes
摘要
Abstract
Xinchengzi basin is located in the southern part of Zalantun volcanic-type uranium prospective metallogenic belt.Its tectonic evolution and magmatic activity patterns hold significant implications for regional uranium exploration.This study focuses on the granite porphyry in Jibutu sector of Xinchengzi basin and investigates its petrogenesis and geological significance of the granite porphyry by systematic petrological,geochemical,zircon U-Pb geochronological,and isotopic geochemical analyses.The results demonstrate that magmatic crystallization ages are 132.7 Ma±1.6 Ma(MSWD=0.16,2σ)and 130.7 Ma±1.7 Ma(MSWD=0.45,2σ),both of which are in Early Cretaceous.The rock chemical composition as a whole is characterized by high silicon,high potassium,low sodium,and magnesium-iron-rich peraluminous.In the primitive mantle-normalized spider diagram of trace elements,obvious alternately appearing serrated peaks and valleys can be observed.Among them,three elements Nb,Sr,and P form an obvious"V"shape,indicating the enrichment of large ion lithophile elements such as Rb and K and high field strength elements such as Th,U,and Hf,and the depletion of elements such as Nb,Sr,and P,which are the characteristics of A2-type granite by crustal melting.The ratios of(87Sr/86Sr)i and 143Nd/144Nd range from 0.705 982 to 0.706 098 and from 0.512 354 to 0.512 375 respectively.εNd(0)is between-5.13 and-5.54,εNd(t)is between-3.6 and-4.1,and the two-stage isotopic model age TDM2 is between 1 221 Ma and 1 260 Ma,indicating that the magma was originated from the depleted mantle which were frequently participated by crustal materials during the ascending and migrating process.The research result suggest that the granite was formed in an extensional environment after the collision,which provide a clue to the subduction of the Paleo-Pacific Plate towards Eurasian Continent.关键词
A型花岗岩/Sr-Nd同位素/锆石U-Pb年龄/俯冲环境/新城子盆地/林西Key words
A-type granite/Sr-Nd isotope/zircon U-Pb age/subduction environment/Xinchengzi basin/Linxi分类
天文与地球科学引用本文复制引用
王天奇,王常东,郝晓飞,董小宇,林天发,周舰,于兵..林西新城子盆地吉布吐地段花岗斑岩成因和地质意义:年代学、地球化学和同位素制约[J].铀矿地质,2025,41(5):836-852,17.基金项目
中国核工业地质局项目"河北省张北-内蒙古突泉地区铀-多金属矿资源调查评价与勘查"(编号:202312)资助. （编号:202312）
