Surface and subsurface geology of the Hontomín structure, Western Pyrenees

A detailed geological study was conducted in the Hontomín area in the western Pyrenees, Northern Spain, focusing on structural characterization by integrating available subsurface data with a newly developed surface geological map. It reveals a relatively simple surface structure, with the Upper Cretaceous generally dipping gently eastward, except at the southern margin, where they are deformed into tight E-W-trending folds. In contrast, the unconformable Cenozoic layers dip only a few degrees southward. However, seismic data interpretation reveals a much more complex subsurface structure. It is dominated by a broad dome, cored by Upper Triassic salt, which has significantly influenced the overlying stratigraphy and structure. Above the salt, the Jurassic and Lower Cretaceous units exhibit moderate folding, a deformation style that is not apparent at the surface. The deep structure is controlled by a major E-W trending thrust fault, which is not clearly expressed at surface except through small-scale, tight folds aligned in the same direction. This study highlights the importance of integrating surface mapping with geophysical data, both for accurately interpreting subsurface geology when planning for CO₂ injection operations.

针对西班牙北部比利牛斯山脉西部的洪托明（Hontomín）区域开展了一项详细的地质研究，通过整合现有地下数据与全新编制的地表地质图，聚焦于构造特征刻画。研究揭示地表构造整体相对简单：上白垩统地层总体呈平缓东倾态势，仅在南部边缘区域发生强烈变形，形成东西向紧密褶皱。与之相对，不整合覆盖的新生代地层仅以极缓角度向南倾斜。然而，地震资料解释结果显示地下构造要复杂得多：该地下构造以宽阔穹隆为主体，其核部发育上三叠统盐岩，该盐岩对上覆地层的沉积序列与构造变形产生了显著影响。在盐岩上方，侏罗系与下白垩统地层表现出中等程度的褶皱变形，这种变形样式在地表并无明显显现。深部构造受一条大型东西向逆冲断层控制，该断层在地表并无清晰表露，仅在局部区域出现沿同一方向展布的小型紧密褶皱作为间接指示。本研究凸显了整合地表填图与地球物理资料的重要性——这对于规划二氧化碳（CO₂）注入作业时准确解读地下地质情况至关重要。