The deep-rooted serpentinite mud volcanism of the Mariana Forearc

申请方提出了两个主要研究目标：确定马里亚纳前弧活泥火山建筑物的空间和时间变异性，并将实验室分析产生的数据集与成熟增生复合体（日本地中海）深层泥火山的类似数据相结合。这种比较将允许建立泥火山在不同类型的俯冲带的功能，并将揭示其作为俯冲板块的直接窗口的作用。这一建议的第一部分是集中在马里亚纳会聚边缘，西北太平洋，作为一个古老的，寒冷的俯冲带托管地球上最大的泥火山。在IODP 366期间，将在三个泥火山的山顶和侧面钻三个断面，这些泥火山的尺寸和深度不同，距离海沟的距离也越来越远。MARUM（不莱梅大学）的测量重点是确定泥浆基质流变性及其矿物学之间的关系，方法是测试蛇纹石泥浆的单轴固结，并确定其半定量矿物学成分，特别注意可能导致流变学差异的粘土部分。申请人还计划通过测量碎屑和泥质基质的粘度、渗透率和指数特性，探索进料通道几何形状与泥火山产物来源之间的联系。这些测量将允许通过对喷发机制的初步地球物理表征，将泥火山大厦与其深层起源联系起来。第二部分是将马里亚纳数据与其他两个泥火山活动感兴趣的地区，地中海海脊和南海海槽。这是通过利用泥火山的发生作为对深层过程的自然洞察来理解所谓的俯冲工厂的更大努力的一部分。这三个位置代表了泥火山扎根于上板块或下板块不同深度的区域。马里亚纳前弧的钻探活动是一项与ODP 160相当的努力，当时完成了地中海海脊增生复合体的两个样带。过去已使用不同技术对ODP 160的沉积物进行了广泛分析，并构成申请人进行比较分析的起点。除此之外，将通过在本提案第一部分期间进行的大多数相同测量来分析来自地中海海脊和南海的MARUM考察的沉积物，以将这三个关键区域（几何形状上有很大不同）联系起来，并研究泥火山产物的流变行为如何影响俯冲带的流体和固体平衡。

The applicant formulates two main research goals: determine the spatial and temporal variability in active mud volcanoes edifices of the Mariana forearc and integrate the datasets produced from the laboratory analyses with similar data from deep-seated mud volcanoes in mature accretionary complexes (Mediterranean, Japan). This comparison will allow to establish the function of mud volcanoes in different types of subduction zones and will shed new light on their role as direct windows into the subducting slab. The first part of this proposal is focusing on the Mariana convergent margin, northwestern Pacific Ocean, as an old, cold subduction zone hosting the largest mud volcanoes on earth. During IODP 366, three transects will be drilled on summits and flanks of three mud volcanoes with different dimensions, depths and located at increasing distances from the trench. Particular emphasis of the measurements at MARUM (University of Bremen) will be on determining the relationship between the mud matrix rheology and its mineralogy, by testing the serpentine mud with for uniaxial consolidation and determining its semi quantitative mineralogical composition with a specific attention on the clay fraction, probable responsible for the rheological differences. The applicant is also planning to explore the connection between feeder channel geometry and source of the mud volcanoes products by measuring viscosity, permeability and index properties of both clasts and mud matrix. These measurements will allow linking the mud volcanoes edifices with their deep origins through a preliminary geophysical characterization of the eruption mechanism. The second part consists in integrating the Mariana data with two other areas interested by mud volcanism, the Mediterranean Ridge and the Nankai trough. This is part of a bigger effort to understand the socalled subduction factory by exploiting the occurrence of mud volcanoes as a natural insight into deep processes. These three settings represent regions where the mud volcanoes are rooting in the upper plate or in the downgoing slab at different depths. The drilling campaign on the Mariana forearc is an effort comparable with the ODP 160, when two transect on just as many mud volcanoes of the Mediterranean Ridge accretionary complex were completed. The sediments from ODP 160 have been extensively analyzed with different techniques in the past and constitute the applicant starting point to base a comparative analysis. In addition to that, sediments from MARUM expeditions from both the Mediterranean Ridge and Nankai will be analyzed through most of the same measurements performed during the first part of this proposal to relate these three key areas (as substantially different in geometry) and examine how the rheological behavior of the mud volcanoes products is affecting the fluid and solid balance in subduction zones.