LISTVEIN: Multiscale structure evolution during peridotite carbonation and hydration in an oceanic subduction zone: a case study of listvenite in the Oman Ophiolite

LISTVEIN：大洋俯冲带橄榄岩碳化和水化过程中的多尺度结构演化：阿曼蛇绿岩中的 Listvenite 案例研究

• 批准号: 420525991
• 负责人: Professor Dr. Klaus Reicherter, since 9/2019
• 金额: --
• 依托单位: Lehr- und Forschungsgebiet Geologie - Endogene Dynamik (GED) (aufgelöst)
• 依托单位国家: 德国
• 项目类别: Infrastructure Priority Programmes
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/420525991?language=en
• 关键词: LISTVEIN; Multiscale; structure; evolution; during

Listvenites in the Oman Ophiolite formed from oceanic mantle peridotite thrust over carbonate-bearing sediments in the hanging wall of a subduction zone. In this example of large scale peridotite hydration and carbonation processes, core BT1 of the ICDP Oman Drilling Project (OmDP) provides a unique sample. Although listvenites record carbon fluxes in oceanic subduction zones and are a possible natural analogue for carbon capture and storage via mineralization, the processes by which this carbonation occurs are not well understood, calling for work to understand the evolution of this natural example. We propose a micro- and macrostructural study of deformation and reaction structures in listvenite and serpentinized peridotite in Core BT1. Using optical and electron microscopy (ViP, CL, BIB-SEM, EDX, EBSD, QEMSCAN) integrated with our core description data and with the state of the art image data (core scans, X-ray CT, hyperspectral, XRF) collected by OmDP, we will focus on (i) the different generations of fault, cataclasite and fracture and vein structures modifying the listvenite microstructure, analyzing overprinting relationships and deformation mechanisms, (ii) the microstructure of listvenite, testing the presence of a ductile shear zone during carbonation, (iii) the microstructure of protolith serpentinites and partially altered peridotites, (iv) microstructures in syntaxial and antitaxial veins to distinguish reaction-induced- from tectonically and pore pressure-induced fracturing, and finally (v) on micro- and nano-porosity and its connectivity to constrain potential fluid pathways in the matrix.We aim to better understand the interplay of force of crystallization, tectonic stress and pore pressure during large scale hydration and carbonation processes in BT1 and test hypotheses on driving forces, structural evolution and fluid transport pathways in this system. More generally, we hope to contribute a process-oriented perspective to studies of mass transfer and element “recycling” in subduction zones, and to understand the effect of mass transfer and mineralogical transformation on plate-boundary deformation.

由海洋地幔橄榄岩形成的阿曼蛇绿岩中的Listvenites在俯冲带的悬挂壁上的含碳酸盐沉积物上推动。在这个大规模橄榄岩水合和碳酸过程的示例中，ICDP阿曼钻井项目（OMDP）的Core BT1提供了独特的样本。尽管Listvenites记录了海洋俯冲带中的碳通量，并且是通过矿化碳捕获和储存的自然模拟，但对这种碳化发生的过程尚未得到充分了解，呼吁工作以了解此自然示例的演变。我们提出了在核心BT1中的Listvenite和蛇状橄榄石中的变形和反应结构的微结构研究。 Using optical and electron microscopy (ViP, CL, BIB-SEM, EDX, EBSD, QEMSCAN) integrated with our core description data and with the state of the art image data (core scans, X-ray CT, hyperspectral, XRF) collected by OmDP, we will focus on (i) the different generations of fault, cataclasite and fracture and vein structures modifying the listvenite microstructure, analyze （ii）碳化过程中延性剪切区的存在，（iii）延性剪切区的存在，（iii）Protolith serpentinites的微观结构以及部分改变的植物植物的微观结构，（IV （v）关于微孔和纳米孔隙率及其与矩阵中潜在流体途径的连通性。我们的目标是更好地了解BT1中大规模水合和碳化过程中结晶力，构造应力和孔隙压力的相互作用，并在该系统中对驱动力，结构进化和流体运输路径进行测试。更普遍地，我们希望为俯冲带中传质和元素“回收”的研究贡献一个面向过程的观点，并了解传质和矿物学转化对板束变形的影响。