Episodicity of structural flow in an active subduction system, new insights from mud volcano's carbonate veins - Scientific Ocean drilling expedition IODP 366
Episodicity of structural flow in an active subduction system, new insights from mud volcano's carbonate veins - Scientific Ocean drilling expedition IODP 366
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DOI：
10.1016/j.margeo.2021.106431
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发表时间：
2021-02-02
期刊：
影响因子：
2.9
通讯作者：
Zhao, J.
中科院分区：
文献类型：
--
作者：
Frery, Emanuelle;Fryer, Patricia;Zhao, J.
本研究的目的是了解马里亚纳弧前蛇纹泥火山的碳酸钙沉淀样品中记录的流体流动的结构事件和情节。这些活动山脉提供了一个独特的窗口，以了解影响俯冲通道混杂带和俯冲太平洋板块的深部构造和流体流动事件。为了建立从俯冲带到泥火山建造的静脉沉淀的概念模型，我们通过对碳酸钙静脉的多学科研究，在国际海洋发现计划（IODP）366号考察期间，在范坦吉斯纳海山侧翼钻探的样品中，碳酸盐岩脉网的结构分析揭示了沉淀和溶解的阶段。最古老的碳酸钙矿物经历了高构造应力和几个程度的硅化。U-Pb测年范围从早白垩世到今天，记录潜在的预收敛事件和校准的马里亚纳泥火山从开始的收敛到今天的一幕式建设。UCC标准化的轻稀土配分模式，Sr-87/Sr-86比值为0.704977 ~ 0.705798，δ O-18特征为18.7 ~ 19.8(%,V-SMOW）的矿脉表明受蛇纹泥特征影响的沉淀流体的混合起源。这些泥火山是在前弧作用下，从俯冲开始到现在间歇性建造的构造活动它们是内部由断层网络组成的复杂系统，提供了可以连续打开或关闭的多个循环路径。
This study's goal is to understand the structural events and episodes of fluid flow recorded in calcium carbonate precipitation sampled in Mariana forearc serpentine mud volcanoes. Those active mounts provide a unique window to deep structural and fluid flow events affecting the subduction channel m 'elange zone and the subducted Pacific Plate.To build a conceptual model of vein precipitations from the subduction zone to the mud volcanoes edifice, we unravelled the origin, timing, and mechanisms of those precipitations with a multidisciplinary study of calcium carbonate veins, from samples drilled in the flank of Fantangisna Seamount during the International Ocean Discovery Program (IODP) Expedition 366.Structural analysis of the carbonate vein network revealed stages of precipitation and dissolution. The most ancient calcium carbonate minerals underwent high tectonic stress and several degrees of silicification. U-Pb dates ranged from Early Cretaceous to present day, recording potential pre-convergence events and calibrating an episodic building of the Mariana mud volcanoes from the start of the convergence to present day. The UCC-normalized LREE pattern, Sr-87/Sr-86 ratios ranging from 0.704977 to 0.705798 and delta O-18 signature 18.7 to 19.8 (%, V-SMOW) of the veins indicate a mixed origin of the precipitated fluids influenced by the serpentine mud signature.Those mud volcanoes were episodically built from the start of the subduction to present day in function of the forearc tectonic activity. They are complex systems internally composed of a fault network providing multiple circulation pathways that can be successively opened or closed.