Are the Taitao granites formed due to subduction of the Chile ridge?
Are the Taitao granites formed due to subduction of the Chile ridge?
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DOI：
10.1016/j.lithos.2009.05.018
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发表时间：
2009-11-01
期刊：
影响因子：
3.5
通讯作者：
Herve, Francisco
中科院分区：
文献类型：
--
作者：
Anma, Ryo;Armstrong, Richard;Herve, Francisco
台陶花岗岩分布于智利南部台陶半岛西端（距现今智利三角洲东南50 km）晚中新世台陶蛇绿岩（5.66 +/- 0.33 Ma ~ 5.19 +/- 0.15 Ma）周围。本文报道了台陶花岗岩的高质量分辨率离子探针（SHRIMP）U-Pb年龄，以阐明蛇绿岩与花岗岩的时间关系，并讨论了花岗岩熔体的成因。其中5个岩体的U-Pb年龄为5.70 ± 0.25 Ma（东南部的Tres Montes岩体）~ 3.92 ± 0.07 Ma（西南部的卡波Raper岩体）。位于蛇绿岩东缘边缘的埃斯特罗Cono、Seno Hopprier和巴伊亚Barrientos岩体的U-Pb年龄为5.17 ± 0.09 Ma ~ 4.88 ± 0.3 Ma。只有在Tres Monies岩体中才常见有嵌岩锆石核。我们的数据表明，生成的花岗岩熔体开始在特雷斯蒙特斯地区时，智利海脊系统的一小段开始俯冲约。六年前。这种岩浆作用涉及沉积物/基底岩石的污染。俯冲脊中心的一部分侵位形成了现今的台陶蛇绿岩，其侵位时间约为5.6Ma。花岗岩熔体的产生继续作为同一脊段俯冲的扩展中心，这可能是由于部分熔融的蛇绿岩和/或洋壳增强了热从上涌地幔下脊。洋脊俯冲过程中发育了多种成分的花岗质岩浆。蛇绿岩的侵位与陆壳的形成几乎同时发生。(C)2009 Elsevier B. V.保留所有权利。
The Taitao granites are distributed around the Late Miocene Taitao ophiolite (5.66 +/- 0.33 Ma to 5.19 +/- 0.15 Ma) exposed at the western tip of the Taitao peninsula, southern Chile, similar to 50 km southeast from the present day Chile triple junction. In this paper, we report sensitive high mass-resolution ion microprobe (SHRIMP) U-Pb ages for the Taitao granites to elucidate the temporal relationship between the ophiolite and granites, and discuss the origin of the granitic melts. Five intrusive bodies of the Taitao granites have U-Pb ages ranging from 5.70 +/- 0.25 Ma (Tres Montes pluton in southeast) to 3.92 +/- 0.07 Ma (Cabo Raper pluton in southwest). The Estero Cono, Seno Hopprier and Bahia Barrientos intrusions that fringe eastern margin of the ophiolite have U-Pb ages ranging from 5.17 +/- 0.09 Ma to 4.88 +/- 0.3 Ma. Recycled zircon cores are common only in the Tres Monies pluton. Our data indicate that the generation of the granitic melts started in the Tres Montes area when a short segment of the Chile ridge system started to subduct ca. 6 Ma ago. This magmatism involved contamination with sediments/basement rocks. A part of the subducting ridge center was emplaced to form the present Taitao ophiolite at similar to 5.6 Ma. Generation of granitic melts continued as the spreading center of the same ridge segment subducted, due perhaps to partial melting of the ophiolite and/or oceanic crust enhanced by heat from upwelling mantle beneath the ridge. Granitic magmas with various compositions developed during subduction of the ridge. Emplacement of the ophiolite and formation of continental crust took place almost simultaneously. (C) 2009 Elsevier B.V. All rights reserved.