中国地质大学张亮亮团队近日研究了新特提斯的延长俯冲起始：来自变质底垫年代学的见解。2025年7月7日出版的《地质学》杂志发表了这项最新成果。

俯冲起始（Subduction initiation, SI）作为板块构造的关键过程，由于地质证据有限，其机制仍不甚明了。变质底垫（Metamorphic soles, MSs）由俯冲板块经历高温变质作用形成，具有揭示俯冲起始关键信息的潜力。研究组通过整合锆石、磷灰石和榍石的U-Pb年龄及其稀土元素配分模式，重新评估了雅鲁藏布江蛇绿岩带（Yarlung Zangbo Ophiolite, YZO）中部变质底垫的形成时代。结果表明，变质底垫的形成时代为145～115 Ma，其原岩形成时代不晚于160 Ma。

该原岩年龄显著老于变质底垫自身及雅鲁藏布江蛇绿岩带主体年龄（130～120 Ma），表明新特提斯洋在雅鲁藏布江缝合带的俯冲起始很可能沿着不同年龄的洋壳岩石圈之间的转换断层/破裂带发生，或沿着大陆边缘发生。变质底垫广泛的年龄范围指示了一个持续近25百万年（m.y.）的长期俯冲起始过程，该过程可划分为两个显著阶段：(1) 停滞阶段（145～133 Ma），以俯冲速率缓慢和地幔贫水（亏损型）为特征；(2) 解锁阶段（133～120 Ma），以俯冲速率加快和上盘快速伸展为特征，最终导致雅鲁藏布江蛇绿岩带的形成。

此外，研究组记录到一个晚于雅鲁藏布江蛇绿岩带的变质底垫晚期阶段（俯冲起始后阶段；120～115 Ma），这表明持续的俯冲作用可在较长时间内持续产生变质底垫。这些观测为新特提斯洋俯冲起始的动力学过程提供了新的认识。

附：英文原文

Title: Protracted subduction initiation of the Neo-Tethys: Insights from metamorphic sole chronology

Author: Jie Shen, Jin-Gen Dai, Kai Yang, Liang-Liang Zhang

Issue&Volume: 2025-07-07

Abstract: Subduction initiation (SI), a key process in plate tectonics, remains poorly understood due to limited geological evidence. Metamorphic soles (MSs), which result from the high-temperature metamorphism of the subducted plate, hold the potential to offer crucial insights into SI. Here we reevaluate the formation time of MSs in the central Yarlung Zangbo Ophiolite (YZO) by integrating zircon, apatite, and titanite U-Pb ages with their rare earth element patterns. The results reveal that formation time of MSs is 145115 Ma, and their protoliths were formed no later than 160 Ma. The significantly older protolith, in comparison to MSs and the majority of YZO ages (130120 Ma), suggests that the Neo-Tethyan SI in the Yarlung Zangbo suture zone likely occurred along a transform fault or fracture zone between oceanic lithosphere with different ages or along a continental margin. The extensive age range for MSs indicates a protracted SI spanning nearly 25 m.y., which can be divided into two distinct stages: (1) the stagnant stage (145133 Ma), marked by a slow subduction rate and a dry mantle; and (2) the unlocking stage (133120 Ma), characterized by an accelerated subduction rate and rapid upper plate extension, leading to formation of the YZO. Additionally, we document a late-stage (post-SI stage; 120115 Ma) of MSs that is younger than the YZO, implying that sustained subduction can produce MSs over extended periods. These observations provide new insights into the dynamics of the Neo-Tethyan SI.

DOI: 10.1130/G53409.1

Source: https://pubs.geoscienceworld.org/gsa/geology/article-abstract/doi/10.1130/G53409.1/659415/Protracted-subduction-initiation-of-the-Neo-TethysredirectedFrom=fulltext