本文選題：巖石地球化學 + 年代學　； 參考：《地質(zhì)學報》2017年01期

【摘要】：新疆中天山巴倫臺地區(qū)廣泛分布著花崗質(zhì)侵入體,本研究對烏瓦門斷裂北側(cè)的花崗質(zhì)侵入體進行了LA-ICP-MS鋯石U-Pb定年,獲得巖體侵位年齡為452.7±1.4Ma和455.5±1.7Ma,屬晚奧陶世。巖石地球化學結(jié)果表明其主要為一套準鋁質(zhì)鈣堿性系列巖石,稀土元素配分圖呈明顯的右傾模式,具有較高的LaN/YbN比值(6.01~23.74)、弱的Eu負異常(δEu=0.67~0.83)。微量元素蛛網(wǎng)圖上巖石總體富集大離子親石元素Rb、Cs、Ba等,虧損高場強元素Nb、Ta及Ti。鋯石原位Hf同位素測定結(jié)果表明,εHf(t)值變化于-14.8~-9.4(平均-12.4),二階段Hf模式年齡(tDM2)變化于1730~1997Ma(平均1871Ma)。上述巖石地球化學特征表明巴倫臺地區(qū)晚奧陶世花崗質(zhì)侵入體形成于火山弧環(huán)境,是幔源巖漿底侵帶來的大量熱能使得早元古代下地殼物質(zhì)發(fā)生部分熔融的產(chǎn)物。綜合分析認為,該期侵入體可能代表了巴倫臺地區(qū)南天山洋盆向北俯沖最早的巖漿記錄。
[Abstract]:Granitic intrusions are widely distributed in the Palentai area of central Tianshan, Xinjiang. The LA-ICP-MS zircon U-Pb dating of granitic intrusions on the northern side of the Wawamen fault has been carried out. The emplacement ages of the intrusions are 452.7 鹵1.4 Ma and 455.5 鹵1.7 Ma, which belong to the late Ordovician. The petrogeochemical results show that it is mainly a set of quasi-aluminite calc-alkaline series rocks, and the REE distribution pattern shows an obvious right-dip pattern, with a high LaN- / YbN ratio of 6.01 ~ 23.74 and a weak negative EU anomaly (未 EU _ (0.67) ~ (0.83). On the trace element cobweb diagram, the rocks are enriched in the large ion lithophile elements RbCsBa-Ba and so on, and the high field strength elements NB, Ta and Ti are depleted. The results of in situ HF isotopic determination of zircon show that the 蔚 Hft values vary from -14.8 to 9.4 (mean -12.4g), and the two-stage HF model age (TDM2) varies from 1730 to 1997 Maa (mean 1871 Ma). The above petrogeochemical characteristics indicate that the late Ordovician granitic intrusions were formed in the volcanic arc environment and were the result of partial melting of the lower crust material from the early Proterozoic due to a large amount of heat generated by the mantle magma submersion. It is considered that the intrusions in this period may represent the earliest magmatic records of the southern Tianshan ocean basin subducting northward in the Balentai area.
【作者單位】： 新疆地質(zhì)調(diào)查院;新疆大學地質(zhì)與礦業(yè)工程學院;
【基金】：中國地調(diào)局大調(diào)查項目“新疆巴倫臺1∶5萬K45E006010、K45E007010、K45E007011、K45E008010、K45E008011五幅區(qū)域地質(zhì)調(diào)查”(編號:1212011140058)資助的成果
【分類號】：P597.3;P588.12

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