{"title":"Control by preexisting morphology on layer-bound faults in the southern Qiongdongnan Basin, NW South China Sea","authors":"","doi":"10.1016/j.jsg.2024.105262","DOIUrl":null,"url":null,"abstract":"<div><p>The ideal development of layer-bound, polygonal faults occurs in an isotropic stress field. However, some populations of layer-bound faults appear to have originated as ‘polygonal’ faults, but display atypical plan-view fault geometries that suggest development under anisotropic stress conditions. High-resolution 2D/3D seismic data in the southern Qiongdongnan Basin displays three tiers of layer-bound faults with distinct strike variations and complex structural patterns that depart from the geometries of isotropic polygonal fault cells. The lower fault tier displays preferred orientations along E-W, NE-SW, NW-SE directions; the middle fault tier shows a primary E-W orientation and a secondary N-S trend; the shallow tier features strong N-S and E-W orientations. Fault patterns in map view include orthogonal, quasi-polygonal and circumferential geometries, among which the orthogonal pattern is dominant in the shallow fault tier. Several factors are inferred to cause these variable geometrical and structural patterns in layer-bound faults, they are: pre-existing tectonic faults, an uplifted region, local slopes, contourite depressions, and large contourite-related channels. The orthogonal fault patterns have longer E-W orientation parallel to the contourite channels and shorter N-S trends perpendicular to the thalwegs. The presence of submarine channels is suggested to locally deflect the stress orientation, which in turn impacts fault patterns.</p></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":null,"pages":null},"PeriodicalIF":2.6000,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Structural Geology","FirstCategoryId":"89","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0191814124002141","RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"GEOSCIENCES, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
The ideal development of layer-bound, polygonal faults occurs in an isotropic stress field. However, some populations of layer-bound faults appear to have originated as ‘polygonal’ faults, but display atypical plan-view fault geometries that suggest development under anisotropic stress conditions. High-resolution 2D/3D seismic data in the southern Qiongdongnan Basin displays three tiers of layer-bound faults with distinct strike variations and complex structural patterns that depart from the geometries of isotropic polygonal fault cells. The lower fault tier displays preferred orientations along E-W, NE-SW, NW-SE directions; the middle fault tier shows a primary E-W orientation and a secondary N-S trend; the shallow tier features strong N-S and E-W orientations. Fault patterns in map view include orthogonal, quasi-polygonal and circumferential geometries, among which the orthogonal pattern is dominant in the shallow fault tier. Several factors are inferred to cause these variable geometrical and structural patterns in layer-bound faults, they are: pre-existing tectonic faults, an uplifted region, local slopes, contourite depressions, and large contourite-related channels. The orthogonal fault patterns have longer E-W orientation parallel to the contourite channels and shorter N-S trends perpendicular to the thalwegs. The presence of submarine channels is suggested to locally deflect the stress orientation, which in turn impacts fault patterns.
期刊介绍:
The Journal of Structural Geology publishes process-oriented investigations about structural geology using appropriate combinations of analog and digital field data, seismic reflection data, satellite-derived data, geometric analysis, kinematic analysis, laboratory experiments, computer visualizations, and analogue or numerical modelling on all scales. Contributions are encouraged to draw perspectives from rheology, rock mechanics, geophysics,metamorphism, sedimentology, petroleum geology, economic geology, geodynamics, planetary geology, tectonics and neotectonics to provide a more powerful understanding of deformation processes and systems. Given the visual nature of the discipline, supplementary materials that portray the data and analysis in 3-D or quasi 3-D manners, including the use of videos, and/or graphical abstracts can significantly strengthen the impact of contributions.