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Geochronology, Geochemistry and Hf Isotope of the Late Mesozoic Granitoids from the Lushi Polymetal Mineralization Area: Implication for the Destruction of Southern North China Craton
Journal of Earth Science ( IF 4.1 ) Pub Date : 2020-04-20 , DOI: 10.1007/s12583-020-1277-y
Yuanyuan Zhai , Shuai Gao , Qingdong Zeng , Shaoxiong Chu

The North China Craton (NCC) is the best example of an Archean craton that has lost its stability in the Late Mesozoic. Although the cratonic destruction is generally considered to have occurred in the Eastern Block and reached a peak in the Early Cretaceous, the exact areal extent of cratonic destruction is debated, especially the southern and northern margin of the NCC. Here we report geochronology, geochemical and Hf isotopic data of the Late Mesozoic granitoids from Lushi polymetal mineralization area (LPMA) in the southern margin of NCC. These results provide new insights into the destruction in the southern margin of the NCC during the Late Mesozoic. Zircon U-Pb dating indicates that eight granitoids intruded in the Late Jurassic to Early Cretaceous (136.8–154.1 Ma), respectively. Geochemical signatures define these granitoids being A-type or I-type granite that formed in an extension setting. In addition, Hf isotopic compositions of zircons from these granitoids vary in a relatively large range, with εHf(t) values and TDM2 ages ranginge from -26.1 to +15.2 and 215 to 2 849 Ma, respectively. The parental magmas were likely derived from diverse sources, including materials of the partial melting of ancient lower crust and mantle-derived mafic magmas in various proportions. Combining with previous studies on the contemporaneous magma-tectonic activities in circum of NCC, we suggest that the rim of NCC was already unstabilized from the Late Jurassic in the LPMA. The subduction of the Paleo-Pacific Plate was the main trigger to the destruction of the southern margin of NCC, which was responsible for the lithospheric extension and thinning, extensive magmatism and mineralization.

中文翻译:

卢氏多金属矿化区晚中生代花岗岩的年代学,地球化学和Hf同位素:对华北克拉通南部破坏的启示

华北克拉通(NCC)是太古代克拉通的最好例子,该克拉通在中生代晚期失去了稳定性。尽管通常认为克拉通破坏发生在东部地块,并在白垩纪早期达到顶峰,但人们仍在争论克拉通破坏的确切范围,特别是北卡罗来纳州北部和北部边缘。在这里,我们报告了NCC南部边缘的卢氏多金属矿化区(LPMA)的晚中生代花岗岩的地质年代学,地球化学和Hf同位素数据。这些结果为晚中生代NCC南缘的破坏提供了新的见解。锆石U-Pb测年表明,在侏罗纪晚期至白垩纪早期(136.8–154.1 Ma)侵入了八种花岗岩。地球化学特征将这些花岗岩定义为在延伸构造中形成的A型或I型花岗岩。此外,这些花岗岩类的锆石的H同位素组成在较大范围内变化,ε)值和Ť DM2年龄分别ranginge从-26.1至15.2和215,以2 849马。父母的岩浆可能来自多种来源,包括古代下地壳和地幔衍生的镁铁质岩浆部分熔融的各种比例的物质。结合以前对NCC周围岩浆构造活动的研究,我们认为LPMA中的侏罗纪晚期,NCC的边缘已经不稳定。古太平洋板块的俯冲是NCC南部边缘破坏的主要诱因,NCC的南部边缘破坏了岩石圈的延伸和变薄,大量的岩浆作用和矿化作用。
更新日期:2020-04-20
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