地质通报2017，Vol.36Issue(10)：1708-1721,14.
辽北德仁组火山岩LA-ICP-MS锆石U-Pb年龄及岩石地球化学特征
LA-ICP-MS zircon U-Pb dating and geochemical characteristics of the volcanic rocks in Deren Formation, northern Liaoning Province
摘要
Abstract
This paper presents detailed petrologic, geochemical and geochronologic data of the volcanic rocks in Deren Formation of Pinggang Basin, northern Liaoning Province. The authors investigated their petrogenesis, formation age and tectonic settings and dis-cussed the thinning time and mechanism of North China Craton. The LA-ICP-MS zircon U-Pb dating was conducted on dacitic breccia-crystal-lithic tuff in Deren Formation and the upper rhyolite. The former yielded 206Pb/238U ages of 246.8±3.5Ma and 169.6± 4.6Ma which are supposed to represent two stages of magmatism, reflecting the Early Triassic and Middle Cretaceous magma activi-ties in the basement of Pinggang Basin. The latter yielded 206Pb/238U age of 117.0 ± 0.9Ma, which indicates that the rhyolites were formed in the Early Cretaceous. Volcanic rocks in Deren Formation are enriched in large ion lithophile elements (e.g., K, Rb, Ba) but are depleted in high field strength elements (e.g., Nb, Ta, Zr, Hf, Y, Yb) . Besides, due to enrichment of LREEs and depletion of HREEs, the REE patterns exhibit right-inclined feature. These geochemical characteristics show that the source of the primitive magma was derived from the crust, and they were probably formed at the setting of volcanic arc along the active continental margins, resulting from remelting of the basement magma rocks. Major changes from positive to negative landform in the study area occurred during 117~135Ma. In combination with wide distribution of extensional basins and metamorphic core complexes, the authors hold that the magma might have been affected by mantle contamination during remelting of these basement rocks, and the thinning of lith-osphere might have occurred during Early Cretaceous (earlier than 117±1.2Ma) , which resulted in the delamination.关键词
平岗盆地/德仁组火山岩/LA-ICP-MS锆石U-Pb测年/岩石圈减薄/英安质角砾晶屑岩屑凝灰岩/流纹岩Key words
Pinggang Basin/volcanic rocks in Deren Formation/LA-ICP-MS zircon U-Pb dating/lithospheric thinning/dacitic breccia-crystal-lithic tuff/rhyolite分类
天文与地球科学引用本文复制引用
豆世勇,刘锦,鲍东明,彭游博,杨仲杰,赵辰,吕行..辽北德仁组火山岩LA-ICP-MS锆石U-Pb年龄及岩石地球化学特征[J].地质通报,2017,36(10):1708-1721,14.基金项目
中国地质调查局项目《辽宁1:5万房木镇、和隆、八棵树、大孤家幅区域地质矿产调查》(编号:12120113057900) （编号:12120113057900）
