Geochronology, geochemistry of the ores-bearing porphyries in the Lailisigao' er region, western Tianshan:Implications for their tectonic setting and mineralization
Geochronology, geochemistry of the ores-bearing porphyries in the Lailisigao' er region, western Tianshan:Implications for their tectonic setting and mineralization
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发表时间：
2009
影响因子：
1.8
通讯作者：
Z. Dong;A. Yu
中科院分区：
文献类型：
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作者：
Z. Dong;A. Yu
西天山位于伊犁板块的北部，是一个典型的西天山造山带。e.准噶尔板块与伊犁盆地之间造山带。莱里斯高尔钼矿床和3571铜矿床位于晚古生代别镇套-可可尔沁岛弧中段，相距不超过1 km。斑岩与成矿关系密切，以二长闪长斑岩和花岗闪长斑岩为主。锆石LA-ICP-MS U-Pb年龄分别为354 ± 0.65Ma和346 ± 1.2Ma，表明它们是早石炭世的同岩浆岩。主、微量元素分析表明，它们是典型的钙碱性火山弧花岗岩，形成于陆弧环境。结合其地质背景，认为该斑岩可能与晚古生代准噶尔板块向南俯冲有关。它们的I_（Sr）和e_（Nd）（t）比值从0。7079比0。7103和-0. 61比-3。71个，表明它们主要来源于地壳（50%~ 70%）和次地幔物质的混合。它们的地球化学成分反映了两个斑岩为同岩浆关系，推测出露于3571铜斑岩中的岩墙对应于莱里斯高尔铜钼斑岩的上部。因此，在3571矿区下方可能存在一个找矿远景区，即来里斯高尔斑岩型铜钼矿。
Western Tianshan is located in the north part of the Yili plate, i. e. , orogenic belt between Junggar plate and Yili basin. The Lailisigao' er Mo deposit and 3571 Cu deposit no more than 1 km distanceare situated in the middle section of the Late Paleozoic Biezhentao-kokirqin island arc. The porphyries closely related to metallogenesis, are predominated by monzodioritic porphyry and granodioritic porphyry. LA-ICP-MS U-Pb zircon dating on the two porphyries yield the average ages of 354±0.65 Ma Ma and 346± 1.2Ma respectively, implying that they are co-magmatic in the early Carbiniferous. Their major- and trace-element compositions suggest that they are the typical calc alkaline volcanic arc granites, formed a continental arc setting. Combined with its geological background, the porphyries might be related to the southward subduction of the Junggar plate during the Late Paleozoic time. Their I_(Sr)and e_(Nd)(t) ratios range from 0. 7079 to 0. 7103 and -0. 61 to -3. 71 respectively, suggesting that they were mainly derived from crust (50%～ 70% ) contaminated by minor mantle materials. Their geochemical compositions reflect that the two porphyries are co-magmatic relationship, and the dykes outcropped in the 3571 copper porphyry was inferred to correspond with the upper part of the Lailisigao' er Cu-Mo porphyry. Thus, there may be a potential region beneath the 3571 mine for prospecting for the Lailisigao' er type porphyry Cu-Mo deposit.