大别山超高压变质带中“脉状”榴辉岩的锆石U-Pb年龄

U-Pb ZIRCON AGES OF THE VEINED ECLOGITE FROM UHPMB IN THE DABIE MOUNTAINS,ANHUI PROVINCE,CHINA

榴辉岩广泛分布于大别山超高压变质带中,出露规模大小不等,成因类型复杂,围岩类型多样,不仅产于基性、超基性岩中,还产于片麻岩、大理岩、石英硬玉岩、变质花岗岩中。对大别山超高压变质带出露的两处"脉状"榴辉岩进行锆石U Pb年龄测定,分别获得上交点年龄(858±25)Ma和(845±150)Ma,下交点年龄(249±20)Ma和(237±13)Ma,表明其原岩形成时代为新元古代,印支期发生过高压—超高压变质作用,与大别山超高压变质带中其他类型的榴辉岩年龄基本一致。

Eclogites distribute in the ultra-high pressure metamorphic belts (UHPMB) in the Dabieshan Mountains,and show different scales. The eclogites have complicated petrogenesis and various host rocks.They can be found not only in basic, ultrabasic rocks, but also in gneisses, marble, quartz jadeitite and metamorphosed granitiod. The U-Pb zircon ages of two 'veined' eclogites were presented from the UHPMB in the Dabieshan Mountains. The ages were (858±25)Ma, (845±150)Ma and (249±27)Ma, (237±13)Ma for upper and lower intercepts. The U-Pb data show that they were formed in Neoprterozoic Era, and underwent a Triassic high pressure-ultra-high pressure metamorphism,which are similar to the ages of the other types of eclogites form UHPMB in the Dabie Mountains.