吕梁地区18亿年的后造山花岗岩:同位素年代和地球化学制约

Post-Orogenic Granites with an Age of 1800 Ma in Luliang Area, North China Craton: Constraints from Isotopic Geochronology and Geochemistry

对吕梁地区的芦芽山辉石石英二长岩和云中山花岗岩进行了全岩主量和微量元素分析 ,锆石SHRIMP的U -Pb同位素年龄分析。结果表明 ,芦芽山辉石石英二长岩和云中山花岗岩在Y +Nb对Rb和Y对Nb图解中均位于板内花岗岩区 ,在花岗岩的R1-R2图解上 ,芦芽山含辉石石英二长岩位于后碰撞隆升 (post collisionuplift)花岗岩区 ,云中山花岗岩位于晚造山 (lateorogenic)花岗岩区 ,它们都属于后造山花岗岩。芦芽山辉石石英二长岩的锆石SHRIMPU -Pb年龄为 1794±13Ma ,云中山花岗岩的年龄为 180 1± 11Ma。 18亿年后造山花岗岩的确定 。

Major,trace element characteristics and zircon U-Pb SHRIMP dating of the Luyashan augite-monzonites and Yunzhongshan granites in Luliang area,Shanxi Provice indicate that the Luyashan augite-monzonites and Yunzhongshan granites belong to the post-orogenic granite. Zircon grains from the Luyashan augite-diorite yield a SHRIMP U-Pb age of 1 794±13 Ma and zircon grains from the Yunzhongshan granite a SHRIMP age of 1 801±11 Ma. Determination of post-orogenic granites at ca. 1 800 Ma provides direct evidence for constraints on the ending time of the orogeny at the end of Paleoproterozoic.