Linking granulites, silicic magmatism, and crustal growth in arcs: Ion microprobe (zircon) U-Pb ages from the Hidaka metamorphic belt, Japan
Linking granulites, silicic magmatism, and crustal growth in arcs: Ion microprobe (zircon) U-Pb ages from the Hidaka metamorphic belt, Japan
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DOI：
10.1130/g23586a.1
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发表时间：
2007-09
期刊：
影响因子：
5.8
通讯作者：
A. Kemp;T. Shimura;C. Hawkesworth;Eimf
中科院分区：
文献类型：
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作者：
A. Kemp;T. Shimura;C. Hawkesworth;Eimf
关于麻粒岩形成所需的极端变质条件是如何获得的，或者这些岩石与地壳生长和分异过程的关系，还没有达成共识。研究年轻麻粒岩提供了两个优点：构造环境可能受到很好的约束，以及可能避免由年轻变质事件叠印造成的模糊性。本文报道了日本北海道新生代日高变质带含斜方辉石麻粒岩、英云闪长岩和辉长岩的首次离子探针U-Pb（锆石）年龄。这些数据支持了两个阶段的演化，这是由于幕上俯冲带岩浆活动（始新世晚期）和弧后伸展（中新世早期）。我们与麻粒岩相变质作用和石榴石-斜方辉石英云闪长岩代镁铁质岩浆下增生和岩石圈减薄，由于日本海在19马开放。因此，日高麻粒岩是地球上最年轻的暴露麻粒岩之一，体现了大陆生长的热响应。
There is no consensus as to how the extreme metamorphic conditions required to form granulites are attained, or how these rocks relate to crustal growth and differentiation processes. Studying young granulites offers two advantages: the tectonic setting is likely to be well constrained, and the ambiguities that result from overprinting by younger metamorphic events are potentially avoided. We report the first ion microprobe U-Pb (zircon) ages for orthopyroxene-bearing granulites, tonalites, and gabbros of the Cenozoic Hidaka metamorphic belt (Hokkaido, Japan) to clarify the magmatic-metamorphic connection in this area. The data support a two-stage evolution for this terrane, which is attributed to episodes of supra-subduction zone magmatism (late Eocene) and back-arc extension (early Miocene). We relate granulite facies metamorphism and garnet-orthopyroxene tonalite generation to mafic magma under-accretion and lithosphere thinning due to the opening of the Japan Sea at 19 Ma. The Hidaka granulites are thus among the youngest exposed granulites on Earth, and manifest the thermal response to continental growth.