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在内蒙古锡林浩特水库地区出露的花岗岩确定为I型花岗岩,具有较高的Cr、Co、Ni丰度。Ca、Al含量和N2O/K2O比值较高,Fe、Mg含量较低。微量元素蛛网图中显示出明显的Nb、Ta、P、Ti负异常。在SiO2-K2O及AFM图中,花岗质岩石投在钙碱性系列区;在构造环境判别图中,花岗质岩石样品都投在火山弧+同碰撞花岗岩区。锆石测年结果显示平均年龄为317.0±4.0Ma,属晚石炭世。这套晚石炭世岛弧花岗岩的存在,表明加里东期古亚洲洋并未完全关闭,晚石炭世时仍然存在洋壳的俯冲消减事件。从区域上看,是北侧的贺根山洋盆向南俯冲的结果。
The granites exposed in the Xilinhot Reservoir area in Inner Mongolia are identified as type I granites with high abundances of Cr, Co and Ni. The contents of Ca, Al and N2O / K2O are higher, and the contents of Fe and Mg are lower. Trace elemental cobweb showed obvious negative Nb, Ta, P, Ti anomalies. In the SiO2-K2O and AFM maps, the granitic rocks are cast in the calc-alkaline series; in the tectonic setting discrimination diagram, the granitic rocks are cast in the volcanic arc + co-collisional granite area. The zircon dating shows that the average age is 317.0 ± 4.0Ma, belonging to the Late Carboniferous. The presence of this Late Carboniferous arc granite indicates that the paleo-Asian Ocean in Caledonian was not completely shut down and the subduction of the oceanic crust still occurred in the Late Carboniferous. Regionally, it is the result of a southward subduction of the Hegengshan ocean basin on the north side.