大地构造与成矿学
大地構造與成礦學
대지구조여성광학
GETECTONICA ET METALLOGENIA
2014年
3期
718-728
,共11页
华北板块北缘%斑状二长花岗岩%A型花岗岩%后造山
華北闆塊北緣%斑狀二長花崗巖%A型花崗巖%後造山
화북판괴북연%반상이장화강암%A형화강암%후조산
northern margin of the North China Craton%porphyritic monzogranite%A-type granite%post-orogenic
内蒙古西乌旗阿鲁包格山花岗岩位于华北板块北缘中段，岩性以斑状二长花岗岩为主。本次1/5万区域地质调查工作研究发现其具有如下地球化学特征：高硅(SiO2为71.29%~72.12%)、富碱(Na2O+K2O为8.70%~8.98%)、高钾(K2O为4.93%~5.27%)、富轻稀土元素而亏损重稀土元素(LREE/HREE为7.69~12.18)、明显的负铕异常(δEu为0.08~0.14)、较高的Ga/Al比值(2.96×10-4~4.00×10-4)和Zr+Nb+Ce+Y值(548×10-6~739×10-6)、富集Rb、Th、K、La、Nd、Hf、Zr和Pb以及亏损Ba、Ta、P和Ti等特征，类似于A型花岗岩。在判别图解上，所有样品均显示了A2型(后造山)花岗岩特征，其形成可能与后造山伸展构造有关。锆石U-Pb年龄为132.19±0.77 Ma (MSWD=4.6)，其形成时代为早白垩世。结合区内分布有大量晚中生代中基性-中酸性火山岩断陷盆地，表明早白垩世测区已进入后造山伸展构造环境。
內矇古西烏旂阿魯包格山花崗巖位于華北闆塊北緣中段，巖性以斑狀二長花崗巖為主。本次1/5萬區域地質調查工作研究髮現其具有如下地毬化學特徵：高硅(SiO2為71.29%~72.12%)、富堿(Na2O+K2O為8.70%~8.98%)、高鉀(K2O為4.93%~5.27%)、富輕稀土元素而虧損重稀土元素(LREE/HREE為7.69~12.18)、明顯的負銪異常(δEu為0.08~0.14)、較高的Ga/Al比值(2.96×10-4~4.00×10-4)和Zr+Nb+Ce+Y值(548×10-6~739×10-6)、富集Rb、Th、K、La、Nd、Hf、Zr和Pb以及虧損Ba、Ta、P和Ti等特徵，類似于A型花崗巖。在判彆圖解上，所有樣品均顯示瞭A2型(後造山)花崗巖特徵，其形成可能與後造山伸展構造有關。鋯石U-Pb年齡為132.19±0.77 Ma (MSWD=4.6)，其形成時代為早白堊世。結閤區內分佈有大量晚中生代中基性-中痠性火山巖斷陷盆地，錶明早白堊世測區已進入後造山伸展構造環境。
내몽고서오기아로포격산화강암위우화북판괴북연중단，암성이반상이장화강암위주。본차1/5만구역지질조사공작연구발현기구유여하지구화학특정：고규(SiO2위71.29%~72.12%)、부감(Na2O+K2O위8.70%~8.98%)、고갑(K2O위4.93%~5.27%)、부경희토원소이우손중희토원소(LREE/HREE위7.69~12.18)、명현적부유이상(δEu위0.08~0.14)、교고적Ga/Al비치(2.96×10-4~4.00×10-4)화Zr+Nb+Ce+Y치(548×10-6~739×10-6)、부집Rb、Th、K、La、Nd、Hf、Zr화Pb이급우손Ba、Ta、P화Ti등특정，유사우A형화강암。재판별도해상，소유양품균현시료A2형(후조산)화강암특정，기형성가능여후조산신전구조유관。고석U-Pb년령위132.19±0.77 Ma (MSWD=4.6)，기형성시대위조백성세。결합구내분포유대량만중생대중기성-중산성화산암단함분지，표명조백성세측구이진입후조산신전구조배경。
The Alubaoge granite in Xiwuqi of inner-Mongolia, which is located in the middle segment of the northern margin of North China Craton geologically, consists mainly of porphyritic monzogranite. The Alubaoge granites are characterized by high SiO2 (71.29%~72.12%), high potassium (K2O=4.93%~5.27%, Na2O+K2O=8.70%~8.98%) content, and enriched in LREE, depleted in HREE(LREE/HREE=7.69~12.18), with obviously negative Eu anomaly (δEu=0.08~0.14). While the trace elements are characterized by Rb, Th, K, La, Nd, Hf, Zr, Pb enriched, and Ba, Ta, P, Ti depleted, as well as with high Ga/Al ratio (2.96×10-4~4.00×10-4), high Zr+Nb+Ce+Y value (548×10-6~739×10-6). The chemical signatures belong to A-type granite. In discrimination diagrams, all the samples show geochemical characteristics of A2-type granitoid, which means that the Alubaoge granite may be formed in post-orogenic stage. The zircon LA-ICP-MS U-Pb dating gives a weighted average age of 132.19±0.77 Ma (MSWD=4.6). The age suggests that the granite was emplaced in the Early Cretaceous. Considering the wide distribution of the Late Mesozoic basic and intermediate-acid volcanic rocks in depression basins, the authors suggest that this area was in post-orogenic regime in the Early Cretaceous.
