| 西藏冈底斯斑岩铜矿带埃达克质斑岩含矿性：源岩相变及深部过程约束 |
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| 引用本文：.2005.Copper ore potential of adakitic intrusives in Gangdese porphyry copper belt: Constrains from rock phase and deep melting process [J].Mineral Deposits,24(2):108~121 |
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| 基金项目:国家基础研究规划973项目(2002CB412600)和国家自然科学杰出青年基金(40425014) |
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| 中文摘要:西藏冈底斯斑岩铜钼成矿系统(13.6～16.9 Ma)发育在印-亚大陆后碰撞地壳伸展环境。成矿前斑岩成岩年龄≥17 Ma，以花岗闪长斑岩为主，成矿期斑岩形成于14.5～17.6 Ma之间，以二长花岗斑岩和石英二长斑岩为主，成矿后斑岩为花岗斑岩，其成岩年龄为11.2 Ma。3期斑岩均为高钾钙碱性或钾玄岩系列，地球化学上类似于玄武质下地壳部分熔融产生的埃达克质岩。成矿前斑岩具有最低的ΣREE(27×10-6～45×10-6)、wY(2.9×10-6～3.4×10-6)和wSm/wYb(3.0～4.9)，最高的wZr/wSm值(50～118)；成矿后斑岩具有最高的ΣREE(122×10-6～197×10-6)和wY(8.2×10-6)，中等的wSm/wYb (5.9～6.2)和wZr/wSm值(34～44)；成矿期斑岩总体处于两者之间，其Sr-Nd同位素组成与Cordillera Blanca埃达克质花岗岩类似。研究提出，来自深部的软流圈物质或亏损地幔物质与下地壳物质交换，不仅导致冈底斯加厚、下地壳熔融，而且提供了巨量金属供应。部分熔融首先从下地壳底部开始，逐渐向上部迁移。下地壳石榴石角闪岩部分熔融过程中，残留相由角闪石向石榴石大规模转变导致角闪石的大量分解，释放出大量流体，是冈底斯斑岩含矿性的主导因素。 |
| 中文关键词:地质学 源岩相变 深部过程 埃达克质斑岩 冈底斯斑岩铜矿 |
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| Copper ore potential of adakitic intrusives in Gangdese porphyry copper belt: Constrains from rock phase and deep melting process |
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| Abstract:The Gangdese porphyry Cu_Mo system in southern Tibet (13.6～16.9 Ma) was generated during the post_collision crustal extension. The pre_ore porphyries mainly consist of granodiorite porphyries with ages older than 17 Ma, whereas the porphyries of the ore_forming stage are mostly composed of monzonitic granite and adamellite porphyries with zircon SHRIMP ages ranging between 14.5 and 17.6 Ma. The post_ore porphyries are comprised of granite porphyries with a young Ar/Ar age of 11.2 Ma. Geochemical studies indicate that these porphyries are of shoshonitic and high_K calc_alkaline series, and show geochemical affinity with adakites derived from partial melting of a thickened basaltic lower crust. The pre_ore porphyries have the lowest contents of ΣREE (27×10 -6-6-6-6-6-6-6 |
| keywords:geology, rock phase, deep melting process, adakitic porphyry, Gangdese porphyry copper deposit |
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