Petrogenesis and Tectonic Significance of High-K Calc-Aikaline Granite in the Haoyao’erhudong of Inner Mongolia
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摘要


     Hercynian granite is found developed in Haoyao erhudong gold deposit, a low-intermediate hydrothermal deposit with low-grade ultra-large reserves. Analysis on the granite has shown that the ratio of SiO2 ranges from 71.5% to 73.07%, and the ratio of Na20/ KE O ranges from 0.59 to 0.67 with an average value of 0.64, thus the granite belongs to high-K calc-alkaline series. According to Hark diagram, the content of each element is obviously in line with the variation tendency of SiO2, to express the characteristics of I-type granite. The content of Mg^# ranges from 39 to 49, and its average of 43 is similar to the average value 45.36 of lower crust granulite. The value of REE from 72.64 X 10.6 to 132.6 X 10.6 signifies a low content of rare earth. The ratio of La/YbN ranges from 12. 99 to 34. 13, revealing biggish frac- tionation between LREE and HREE. The distrJibution curve on REE spider chart goes right. The ratio of Ba/Th ranges from 133.93 to 178.93, indicating less influence on the underthrust plate. The content of 3Eu varies from 0.52 to 0.96, with an average of 0.75, indicating negative Eu anomaly from intermediate to a lower level. According to some other geochemical features, it is considered that the ore body is high-K Calc-alkaline I-type granite formed in post-collision environment.

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