Geochmistry and isotopic compositions of metavolcanic and metasedimentary rock-hosted minerals and serpentinite mud pore waters, recovered at the Mariana forearc during IODP Exp366

Few data exist that provide insight into processes affecting the long-term carbon cycle at shallow forearc depths. To better understand the mobilization of carbon in sediments and crust of the subducting slab, we investigated carbonate materials that originate from the subduction channel at the Mariana forearc (< 20 km) and were recovered during International Ocean Discovery Program Expedition 366. The calcium carbonates exist as vein precipitates within metavolcanic and metasedimentary clasts. The clasts represent portions of the subducting lithosphere, including ocean island basalt, that were altered at lower blueschist facies conditions and were subsequently transported to the forearc seafloor by serpentinite mud volcanism. Euhedral aragonite and calcite and the lack of deformation within the veins suggest carbonate formation in a strain-free environment, that is after peak metamorphism affected their hosts. […]

关于影响浅部前弧深度长期碳循环过程的文献数据寥寥无几。为深入探究沉积物和俯冲板块地壳中碳的活化过程，本研究对源于马里亚纳前弧（<20公里）的碳酸盐材料进行了调查，这些材料在国际海洋发现计划第366次远征期间被回收。钙碳酸盐以脉状沉淀的形式存在于元火山岩和元沉积岩的碎屑中。这些碎屑代表了俯冲地壳的部分，包括海洋岛玄武岩，它们在较低级的蓝片岩相条件下发生了变质，并随后被蛇纹石化泥火山作用搬运至前弧海底。晶体良好的方解石和菱镁矿以及脉内未发生变形的现象表明，碳酸盐的形成是在应力释放的环境中进行的，即在其母岩遭受峰值变质作用之后。