Quantitatively Deciphering Paleostrain From Digital Outcrops Model and its Application in the Eastern Tian Shan, China

Abstract

The knowledge of the strain/stress field evolution in time is fundamental to the understanding of the dynamic system. Based on the principle that past tectonic stress should have left traces in the rocks, geologists have been trying to determine the paleostress history from evidence found in rocks for decades. Recent development of techniques for automatic extraction of fracture surfaces from digital outcrop models and estimation of historical shear deformation on rock fractures provide an efficient way of quantitatively acquiring large amounts of high‐quality fracture/fault slip data from outcrops. Unlike traditional paleostress inversion methods whose data are manually collected in the field, the new techniques provide much more detailed information about the strain of the outcrop and a good opportunity to develop quantitative methods for deciphering more realistic paleostrains. In this study, instead of fitting the slip data from several fractures to calculate the overall strain tensor, the local strain tensor is calculated for slip on each fracture from the outcrop. Then, the local strain tensors are grouped into populations corresponding to different strain events using a clustering analysis technique. Theoretical advantages of this new method over the traditional ones are discussed. The applications on outcrops in the eastern Tian Shan area give a clear picture of the late Cenozoic paleostrain variation over space and time and also throw light on the cause for the change in the strain regime in time, the fracture development patterns, and the distribution of shear displacements in fracture networks.

The dynamic energy balance in earthquakes expressed by fault surface morphology

“…And by fitting this theoretical model to θ * max /C from each slip direction on the fracture surface, the amount of quasi steps R G and quasi striations R H can be estimated. Combined with the method proposed by Wang et al (2017) for outcrop fracture surface extraction from point cloud data, the estimated quasi steps and quasi striations data had good applications in tectonics (e.g., Wang and Gao, 2020).…”

A Workflow for Interpretation of Fracture Characteristics Based on Digital Outcrop Models: A Case Study on Ebian XianFeng Profile in Sichuan Basin

“…In addition, some academics have also proposed related technologies and methodologies for fracture characterization research in practical applications. Wang et al (2020) interpreted fracture characteristics based on DOMs for quantitatively deciphering paleostrain [47]. Larssen et al [48] introduced a workflow from digital outcrop to geo-model for fracture characterization research of Upper Permian carbonates in Spitsbergen [48].…”

3D Quantitative Characterization of Fractures and Cavities in Digital Outcrop Texture Model Based on Lidar

“…However, traditional methods for interpreting geological features only use 2D flat photographs, which leads to a lot of inaccuracies [6,7]. In recent years, researchers need more accurate, efficient, and intelligent approaches to analyze the morphological properties of outcrops [8][9][10][11]. Therefore, traditional outcrop research methodologies are unable to suit outcrop research's application demands at this stage.…”