Timing of Tectonic and Magmatic Events in the Philippine Sea Plate since 50 Ma from High-Resolution Magnetostratigraphy of IODP Site U1438
Timing of Tectonic and Magmatic Events in the Philippine Sea Plate since 50 Ma from High-Resolution Magnetostratigraphy of IODP Site U1438
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IODP 站点 U1438 高分辨率磁性地层学对 50 Ma 以来菲律宾海板块构造和岩浆事件的计时
DOI：
10.1002/essoar.10509798.1
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Maffione M
中科院分区：
文献类型：
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作者：
Maffione M
西太平洋的菲律宾海板块是研究俯冲动力学和俯冲起始后上板块岩浆作用演化的独特天然实验室。为了研究这些过程，国际海洋发现计划第 351 号探险队在位于弧后位置的 U1438 地点进行了回收，这是从近代到始新世早期以及下面的火山基底顶部的完整沉积序列。回收的岩心首次提供了机会，以前所未有的细节研究火山事件的类型、产物和时间，这些火山事件标志着伊豆-小博宁-马里亚纳俯冲开始后九州-帕劳火山弧的就位、生长和消亡。在此，我们报告了 U1438 站点的磁地层学，该磁地层学基于从 1,063 个存档半岩心切片和 429 个离散样本中分离出的约 60,000 个剩磁方向。我们识别了 142 个磁反转，并将其中 115 个与地磁极性时间尺度相关联。当与额外的生物地层学和地质年代学约束相结合时，我们的磁地层学可以为 U1438 站点构建高分辨率年龄模型并确定沉积速率的变化。我们发现，在 52-50Ma 俯冲开始和 48.7Ma 玄武岩就位之后，弧后（48.4-45.6Ma）发生了弥漫性火山活动，先于 40.2Ma 九州-帕劳弧真正就位，然后经历了四个成分不同的喷发阶段，直到 28.8Ma。随后太平洋板片的回滚引发了弧裂（28.8-24.3Ma），并最终在四国和帕雷塞维拉盆地发生弧后扩张。
The Philippine Sea Plate in the West Pacific is a unique natural laboratory to study subduction dynamics and the evolution of upper plate magmatism following subduction initiation. To investigate these processes, International Ocean Discovery Program Expedition 351 recovered at Site U1438, located in a rear‐arc position, a complete sedimentary sequence from recent age to the early Eocene and the top of the underlying volcanic basement. The recovered cores offered the opportunity to study for the first time and in unprecedented detail the styles, products, and timing of the volcanic events that marked the emplacement, growth, and demise of the Kyushu‐Palau volcanic arc following the inception of the Izu‐Bonin‐Mariana subduction. Here, we report a magnetostratigraphy for Site U1438 based on ∼60,000 remanence directions isolated from 1,063 archive half core sections and 429 discrete specimens. We identified 142 magnetic reversals and correlated 115 of them with the geomagnetic polarity timescale. When combined with additional biostratigraphic and geochronological constraints, our magnetostratigraphy allowed construction of a high‐resolution age model for Site U1438 and the determination of changes in sedimentation rates. We show that following subduction initiation at 52–50 Ma and the emplacement of basalts in the rear‐arc at 48.7 Ma, a diffuse volcanism in the rear‐arc (48.4–45.6 Ma) preceded the true emplacement of the Kyushu‐Palau arc at 40.2 Ma, which then grew through four compositionally distinct eruptive phases until 28.8 Ma. Subsequent rollback of the Pacific slab triggered rifting of the arc (28.8–24.3 Ma) and ultimately back‐arc spreading in the Shikoku and Parece Vela basins.