SHRIMP zircon U-Pb dating in Jingshan “migmatitic granite”, Bengbu and its geological significance
SHRIMP zircon U-Pb dating in Jingshan “migmatitic granite”, Bengbu and its geological significance
复制标题
DOI：
10.1360/03yd0045
复制
发表时间：
2005
期刊：
影响因子：
--
通讯作者：
Wenliang Xu;Qing-hai Wang;De‐Bin Yang;Xiaochun Liu;Jing-hui Guo
中科院分区：
文献类型：
--
作者：
Wenliang Xu;Qing-hai Wang;De‐Bin Yang;Xiaochun Liu;Jing-hui Guo
景山“混染花岗岩”的岩石学特征和岩浆锆石的赋存特征表明，该花岗岩是由长英质熔体正常结晶形成的。花岗岩中的锆石均具有继承岩心和岩浆成因的细尺度振荡分带边缘。通过对岩浆锆石定年分析，确定花岗岩形成时间为160.2±1.3 Ma。花岗质岩浆的形成可能与三叠纪超高压变质作用后岩石圈地幔和（或）下地壳剥离有关。大部分继承锆石的年龄为217.1±6.6 Ma，与大别-苏鲁造山带UHPM峰值一致。部分继承锆石（433 ~ 722 Ma）形成一条不协调线，上截距年龄为850+85/−68 Ma，下截距年龄为261+100/−140 Ma。这些年龄表明，花岗岩可能是由UHPM密集叠加的华南地块地壳物质部分熔融形成的。UHPM可能是−220 Ma时铅损失最大的原因。
The petrographic characteristics of Jingshan “migmatitic granite” and the occurrence of the magmatic zircons indicate that the granite was formed by normal crystallization of felsic melts. All zircons in the granite have inherited cores and fine-scale oscillatory zoning rims of magmatic origin. It is realized that the granite was formed at 160.2±1.3 Ma through dating magmatic zircons. The generation of the granitic magma could be related to the lithospheric mantle and/or lower crust delamination after the ultrahigh pressure metamorphism (UHPM) in Triassic. Most inherited zircons yield the ages of 217.1±6.6 Ma, which is consistent with the peak UHPM in the Dabie-Sulu orogenic belt. Some of the inherited zircons (433–722 Ma) constitute a discordia line with the upper intercept age of 850+85/−68 Ma and a lower intercept age of 261+100/−140 Ma. These ages imply that the granite could be derived from the partial melting of the crustal materials of the South China Block that was intensively superimposed by the UHPM. The UHPM could be the reason for the major Pb loss at −220 Ma.