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内蒙古达茂旗阿拉格敖包地区位于华北板块北缘增生带。对区内英云闪长岩岩石地球化学研究表明:岩石具有较低的w(SiO2)(68.71%~70.53%)和较高的w(Al2O3)(13.82%~14.42%),贫碱(w(Na2O+K2O)=5.69%~6.37%)、富钠贫钾(Na2O/K2O=6.29~9.40)的特点,A/CNK值为0.98~1.26,显示铝弱饱和;岩石稀土总量较低(89.2×10-6~132.94×10-6),轻重稀土分馏不明显[(La/Yb)N=2.75~4.57],具有弱的负铕异常和负铈异常;相对富集不相容元素Rb,Th,U,LREE,亏损Ba,Ta,Nb,Sr,P,Ti等高场元素;属准铝质-弱过铝质低钾I型花岗岩。分析表明,英云闪长岩总体经历了较低程度的部分熔融和结晶分异,源区为下地壳基性岩部分熔融,同时混有地壳物质;构造环境为内陆造山环境,指示华北板块与西伯利亚板块在二叠纪末已完全闭合,英云闪长岩是在造山后的伸展环境下,地幔上涌与地壳中具有洋壳性质的岩石相互作用而形成,具有岛弧花岗岩性质,为滞后型岩浆岩,代表了岩浆来源具有壳幔混合的特征。
Inner Mongolia Dahmaoqi Aragou Aobao area is located in North China Plate North margin of the belt. The lithogeochemical study of the tonalites in the area shows that the rocks have lower w (SiO2) (68.71% ~ 70.53%) and higher w (Al2O3) (13.82% ~ 14.42% (Na2O + K2O) = 5.69% ~ 6.37%), Na / K2O = 6.29 ~ 9.40, A / CNK value is 0.98 ~ 1.26, which shows weakly saturated aluminum; 89.2 × 10-6 ~ 132.94 × 10-6). The fractional light and heavy rare earth fractionation is not obvious [(La / Yb) N = 2.75-4.57], with weak negative europium anomaly and negative cerium anomaly. Relative enrichment of incompatible elements Rb , Th, U, LREE, depleted Ba, Ta, Nb, Sr, P, Ti and other high-field elements; The analysis shows that the diagenetic monolites generally undergo a relatively low level of partial melting and crystallization differentiation. The source area is partly melted by the underlying crustal basic rocks with mixed crustal materials. The tectonic setting is an inland orogenic environment, indicating that the North China plate The Siberian plate was completely closed at the end of the Permian. The British diorites were formed after the orogenic extension and the upwelling of the mantle interacted with the crustal oceanic crustal rocks. Hysteresis-type magmatic rocks represent a mixture of crust and mantle from magmatic sources.