当前位置: X-MOL 学术Geology › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Focused fluid seepage related to variations in accretionary wedge structure, Hikurangi margin, New Zealand
Geology ( IF 5.8 ) Pub Date : 2019-10-28 , DOI: 10.1130/g46666.1
Sally J. Watson 1 , Joshu J. Mountjoy 1 , Philip M. Barnes 1 , Gareth J. Crutchley 2, 3 , Geoffroy Lamarche 1, 4 , Ben Higgs 1, 5 , Jess Hillman 2 , Alan R. Orpin 1 , Aaron Micallef 6 , Helen Neil 1 , John Mitchell 1 , Arne Pallentin 1 , Tim Kane 1 , Susi Woelz 1 , David Bowden 1 , Ashley A. Rowden 1, 7 , Ingo A. Pecher 4
Affiliation  

Hydrogeological processes influence the morphology, mechanical behavior, and evolution of subduction margins. Fluid supply, release, migration, and drainage control fluid pressure and collectively govern the stress state, which varies between accretionary and nonaccretionary systems. We compiled over a decade of published and unpublished acoustic data sets and seafloor observations to analyze the distribution of focused fluid expulsion along the Hikurangi margin, New Zealand. The spatial coverage and quality of our data are exceptional for subduction margins globally. We found that focused fluid seepage is widespread and varies south to north with changes in subduction setting, including: wedge morphology, convergence rate, seafloor roughness, and sediment thickness on the incoming Pacific plate. Overall, focused seepage manifests most commonly above the deforming backstop, is common on thrust ridges, and is largely absent from the frontal wedge despite ubiquitous hydrate occurrences. Focused seepage distribution may reflect spatial differences in shallow permeability architecture, while diffusive fluid flow and seepage at scales below detection limits are also likely. From the spatial coincidence of fluids with major thrust faults that disrupt gas hydrate stability, we surmise that focused seepage distribution may also reflect deeper drainage of the forearc, with implications for pore-pressure regime, fault mechanics, and critical wedge stability and morphology. Because a range of subduction styles is represented by 800 km of along-strike variability, our results may have implications for understanding subduction fluid flow and seepage globally.

中文翻译:

与新西兰 Hikurangi 边缘增生楔形结构变化相关的集中流体渗漏

水文地质过程影响俯冲边缘的形态、力学行为和演化。流体供应、释放、迁移和排水控制流体压力并共同控制在增生和非增生系统之间变化的应力状态。我们汇编了十多年已发表和未发表的声学数据集和海底观测,以分析新西兰 Hikurangi 边缘集中流体排出的分布。我们数据的空间覆盖范围和质量对于全球俯冲边缘来说是非常出色的。我们发现集中流体渗流是普遍存在的,并且随着俯冲环境的变化而从南向北变化,包括:楔形形态、收敛速度、海底粗糙度和传入太平洋板块上的沉积物厚度。全面的,集中渗流最常见于变形的止回器上方,在逆冲脊上很常见,尽管水合物无处不在,但在锋楔中基本上不存在。集中的渗流分布可能反映了浅层渗透结构的空间差异,而扩散流体流动和渗流也可能在低于检测限的范围内发生。根据流体与破坏天然气水合物稳定性的主要逆冲断层的空间重合,我们推测集中渗流分布也可能反映了弧前更深的排水,对孔隙压力状态、断层力学和临界楔稳定性和形态有影响。由于一系列俯冲类型由 800 公里的沿走向变异性代表,我们的结果可能对理解全球俯冲流体流动和渗流有影响。
更新日期:2019-10-28
down
wechat
bug