LA-ICP-MS ZIRCON U-Pb DATING AND GEOCHEMISTRY OF WOLONGQUAN INTRUSION IN GAIZHOU, SOUTHERN LIAONING PROVINCE
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摘要: 卧龙泉岩体分布于辽宁南部盖州市卧龙泉镇，岩性主要为似斑状黑云母二长花岗岩，岩石锆石206Pb/238U年龄加权平均值为1888.4±5.3 Ma，形成时代为古元古代.卧龙泉似斑状黑云母二长花岗岩地球化学特征显示，Na2O/K2O均值为0.70，属高钾钙碱性系列；里特曼指数σ平均值为2.18，属钙碱系列；铝饱和指数A/CNK平均值为1.16，属过铝型；岩石中稀土元素总量平均值为299.04×10-6，稀土元素配分模式右倾，属具中负铕异常的轻稀土富集、重稀土亏损型，富集大离子亲石元素，亏损高场强元素，具有活动陆缘钙碱性岩系特征，属于同碰撞科迪勒拉型（I型）花岗岩，应与古元古代造山运动造成下地壳加厚熔融有关.Abstract: The Wolongquan intrusion, distributed in Wolongquan Town, Gaizhou City of southern Liaoning Province, is lithologically composed of mainly porphyritic biotite monzogranite, with the LA-ICP-MS zircon U-Pb age of 1888.4±5.3 Ma, forming in the Paleoproterozoic. The geochemical characteristics of the rock body show that the average value of Na2O/K2O is 0.70, belonging to high-K calc-alkaline series. The average Rittmann index σ of 2.18 also indicates calc-alkaline series. The A/CNK ratio is averagely 1.16, representing a peraluminous type. The average of total REE content is 299.04×10-6 with right-dipping distribution patterns, characterized by moderately negative Eu anomaly with enrichment of LREEs and depletion of HREEs, enriched LILEs and depleted HFSEs, which are the features of active continental margin calc-alkaline series, belonging to the syn-collision I-type Cordillera granite. From the above, it can be inferred that the intrusion should be related to the thickening and melting of the lower crust caused by Paleoproterozoic orogeny.
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Key words:
- Wolongquan intrusion /
- zircon U-Pb age /
- geochemistry /
- southern Liaoning Province
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