摘要
In North Xinjiang there is an alkali granite belt extending in the NW-SE direction along the southern band of the Ulungur River and running parallel to the suture zone,i.e.,Aermantai-Zhaheba Ophiolitic Melange Zone ,between the Junggar Plate and the Altay Orogenic Belt.Whole -rock Rb-Sr isochron ages of the Ulungur alkali granites are within the range of 292-309Ma, showing that they were genetically connected with the latest episode of Hercynian magmatism subsequent to the syncollision S-type and post-collision uplifting I-type granitoids in the Altay region .The alkali granites are miner-alogically characterized by the occurrence of aegirine and arfvedsonite and chemically by high silicon and alkali,low calcium and magnesium and abundant high-field elements, being typical A-type granites .The alkali granites were formed in the final stage of the Hercynian calc-alkaline magmatic cycle in a very short period of time .They are in line with the post-orogenic A-type(PA-type)granites, implying that the tectonic regime was changed from compression to extension.
In North Xinjiang there is an alkali granite belt extending in the NW-SE direction along the southern bank of the Uluugur River and running parallel to the suture zone, i.e., Aermantai-Zhaheba Ophiolitic Melange Zone, between the Junggar Plate and the Altay Orogenic Belt. Whole-rock Rb-Sr isochron ages of the Ulungur alkali granites are within the range of 292- 309Ma, showing that they were genetically connected with the latest episode of Hercynian magmatism subsequent to the syncollision S-type and post-collision uplifting I-type granitoids in the Altay region. The alkali granites are miner-alogically characterized by the occurrence of aegirine and arfvedsonite and chemically by high silicon and alkali, low calcium a.nd magnesium and abundant high-field elements, being typical A-type granites. The alkali granites were formed in the final stage of the Hercynian calc-alkaline magmatic cycle in a very short period of time. They are in line with the post-orogenic A-type (PA-type) granites, implying that the tectonic regime was changed from compression to extension.
基金
National Natural Science Foundation of China
