Repeated metamorphism in the pelitic granulites of the Hidaka metamorphic belt, Hokkaido, Japan: Implications for the formation of the present-day trench-arc-basin system in NE Asia
Repeated metamorphism in the pelitic granulites of the Hidaka metamorphic belt, Hokkaido, Japan: Implications for the formation of the present-day trench-arc-basin system in NE Asia
复制标题
日本北海道日高变质带泥质麻粒岩的反复变质作用：对当今东北亚海沟-弧-盆地系统形成的影响
DOI：
10.1111/jmg.12701
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发表时间：
2022
影响因子：
3.4
通讯作者：
k. Niida
中科院分区：
文献类型：
--
作者：
Jinrui Zhang;Wenliang Xu;Yu Dong;Zheng Ji;Chunjing Wei;Shuang Tang;Yibing Li;k. Niida
对东北亚地区从活动大陆边缘到沟弧盆体系构造转换的时间和机制进行了讨论。在这项研究中，我们报告的压力-温度-时间（P-T-t）路径的基础上，岩相学观察，相平衡模型，锆石和金红石的U-Pb年龄的泥质麻粒岩在日高变质带（北海道，日本）。麻粒岩的早相矿物组合为十字石+硅线石+黑云母+斜长石+石英+金红石/钛铁矿，峰相矿物组合为石榴子石+黑云母+堇青石+斜长石+石英+金红石/钛铁矿，石榴子石变斑晶内共生尖晶石+堇青石±硅线石。相平衡模型表明变质作用有两个阶段，P-T条件分别为~6 kbar/620-670°C和~6 kbar/850°C。因此，麻粒岩的顺时针P-T路径被重建，显示出近等压温度增加到峰值条件和峰后冷却。麻粒岩中锆石和金红石的U-Pb定年结果表明，麻粒岩的变质年龄可分为两组，分别为c. 37 Ma和19 Ma，分别与早期角闪岩相和晚期麻粒岩相变质作用有关。从以前的工作在东北亚大陆边缘的岩浆活动的年龄与这些变质年龄重叠，并在泥质麻粒岩的两个阶段的变质作用归因于离散的超俯冲带岩浆活动（晚始新世，c。37 Ma）和弧后伸展（早中新世，24-19 Ma）。因此，我们认为日高变质带经历了两期变质作用，代表了两次脉冲式的、分离的热事件。此外，我们认为麻粒岩相变质作用与24-19 Ma日本海打开期间的基性岩浆底侵作用和岩石圈减薄有关，这是由于板片回滚和东北亚海沟后退过程。
The timing and mechanism of the tectonic transition from an active continental margin to a trench‐arc‐basin system in NE Asia are debated. In this study, we report the pressure–temperature–time (P–T–t) path of this transition based on petrographic observations, phase‐equilibrium modelling, and U–Pb ages of zircon and rutile from pelitic granulites in the Hidaka metamorphic belt (Hokkaido, Japan). The granulites contain an early phase mineral assemblage of staurolite + sillimanite + biotite + plagioclase + quartz + rutile/ilmenite, a peak phase granulite assemblage of garnet + biotite + cordierite + plagioclase + quartz + rutile/ilmenite and a symplectic intergrowth of spinel + cordierite ± sillimanite within garnet porphyroblasts. Phase‐equilibrium modelling indicates two phases of metamorphism withP–Tconditions, respectively, of ~6 kbar/620–670°C and ~6 kbar/850°C. A clockwiseP–Tpath was thus reconstructed for the granulites, showing a near‐isobaric temperature increase to the peak conditions and a post‐peak cooling. U–Pb dating of zircon and rutile in the granulites yielded two groupings of metamorphic ages at c. 37 Ma and 19 Ma, related to early phase amphibolite facies and late phase granulite facies metamorphism, respectively. The age of magmatism from the previous work at the NE Asian continental margin overlaps with these metamorphic ages, and the two phases of metamorphism in the pelitic granulites is attributed to discrete episodes of supra‐subduction‐zone magmatism (late Eocene, c. 37 Ma) and back‐arc extension (early Miocene, 24–19 Ma). Consequently, we suggest that the Hidaka metamorphic belt has undergone two phases of metamorphism, which represent two pulsed and separated thermal events. Moreover, we relate the granulites facies metamorphism to the underplating of mafic magma and lithospheric thinning during the opening of the Japan Sea at 24–19 Ma, which is attributed to slab rollback and trench retreat processes in NE Asia.