The partially eclogitized crustal rocks on Holsnøy in the Bergen Arcs, Norway, indicate that eclogitization is caused by the interplay of brittle and ductile deformation promoted by fluid infiltration and fluid‐rock interaction. Eclogitization generated an interconnected network of millimeter‐to‐kilometer‐wide hydrous eclogite‐facies shear zones, which presumably caused transient weakening of the mechanically strong lower crust. To decipher the development of those networks, we combine detailed lithological and structural mapping of two key outcrops with numerical modeling. Both outcrops are largely composed of preserved granulite with minor eclogite‐facies shear zones, thus representing the beginning phases of eclogitization and ductile deformation. We suggest that deformation promoted fluid‐rock interaction and eclogitization, which gradually consumed the granulite until fluid‐induced reactions were no longer significant. The shear zones widen during progressive deformation. To identify the key parameters that impact shear zone widening, we generated scale‐independent numerical models, which focus on different processes affecting the shear zone evolution: (i) rotation of the shear zones caused by finite deformation, (ii) mechanical weakening due to a limited amount of available fluid, and (iii) weakening and further hydration of the shear zones as a result of continuous and unlimited fluid supply. A continuous diffusion‐type fluid infiltration, with an effective diffusion coefficient around , coupled with deformation is prone to develop structures similar to the ones mapped in field. Our results suggest that the shear zones formed under a continuous fluid supply, causing shear zone widening, rather than localization, during progressive deformation.

中文翻译：

---

亚稳态干硬下壳初凝过程中含水剪切区的变宽—挪威西部的霍尔斯诺伊（Holsnøy）

挪威卑尔根弧区Holsnøy上部分凝结的地壳岩石表明，凝结是由于流体渗透和流体-岩石相互作用促进脆性和延性变形的相互作用而引起的。晶化作用产生了一个相互联系的网络，该网络由毫米到千米宽的含水榴辉岩相剪切带构成，这大概导致了机械强度较高的下地壳的短暂减弱。为了解密这些网络的发展，我们将两个关键露头的详细岩性和结构映射与数值建模相结合。两种露头都主要由保存的粒状花岗岩组成，并具有少量的榴辉岩相剪切带，因此代表了岩石化和韧性变形的开始阶段。我们认为变形促进了流体-岩石相互作用和凝结作用，逐渐消耗了花岗石，直到流体诱导的反应不再重要为止。在渐进变形过程中，剪切区变宽。为了确定影响剪切带展宽的关键参数，我们生成了与比例无关的数值模型，该模型关注影响剪切带演化的不同过程：（i）有限变形引起的剪切带旋转，（ii）由于有限数量的可用流体，以及（iii）由于连续不断地无限制的流体供应而使剪切区变弱和进一步水化。连续扩散型流体渗透，有效扩散系数约为 为了确定影响剪切带展宽的关键参数，我们生成了与比例无关的数值模型，该模型关注影响剪切带演化的不同过程：（i）有限变形引起的剪切带旋转，（ii）由于有限数量的可用流体，以及（iii）由于连续不断地无限制的流体供应而使剪切区变弱和进一步水化。连续扩散型流体渗透，有效扩散系数约为 为了确定影响剪切带展宽的关键参数，我们生成了与比例无关的数值模型，该模型关注影响剪切带演化的不同过程：（i）有限变形引起的剪切带旋转，（ii）由于有限数量的可用流体，以及（iii）由于连续不断地无限制的流体供应而使剪切区变弱和进一步水化。连续扩散型流体渗透，有效扩散系数约为 （iii）由于连续和无限的流体供应而使剪切区变弱和进一步水化。连续扩散型流体渗透，有效扩散系数约为 （iii）由于连续和无限的流体供应而使剪切区变弱和进一步水化。连续扩散型流体渗透，有效扩散系数约为，加上变形，很容易发展出类似于野外绘制的结构。我们的结果表明，在连续的流体供应下形成的剪切带，在渐进形变期间导致剪切带变宽，而不是局部化。