Mechanical analysis and seismic profile of the geometry of fault-related folds
Speaker: yu-sheng Liang
Abstract
A mechanical model of fault-related folds, comprised of an anisotropic cover overlying displaced, rigid basement blocks, is used to investigate the influence of various parameters on theoretical fold form: shape and dip of basement fault, strength of basement-cover contact, and degree of anisotropy of the cover. We show that the degree of anisotropy in the cover largely influences the geometry of the forelimb of the fault-related fold. Folds produced in isotropic cover display forelimbs that taper from large dip angles near the basement-cover contact to low dip angles at the ground surface. In contrast, dips in the forelimbs of folds in anisotropic cover are nearly uniform with depth. Folds in isotropic cover overlying straight basement faults closely resemble the fold forms produced by the trishear kinematic model while fold forms in anisotropic cover more closely resemble folds produced by parallel kink geometric constructions. In other way, we investigates how and if experts use structural models in the interpretation of a seismic image from a deepwater fold-thrust belt. This has implications for the general applicability of structural models in interpretation. The results show that in the majority of cases experts produced interpretations that were compliant with key features in existing structural models. Those interpretations that were less compliant to existing models, better accounted for features present in natural and experimental analogues.
Reference
Kaj M. Johnson and Arvid M. Johnson, 2002. Mechanical analysis of the geometry of fault-related folds. Journal of Structural Geology Volume 24, Issue 3, March 2002, Pages 401-410.
Taija Torvela , Clare E. Bond, 2011. Do experts use idealized structural models? Insights from a deepwater fold-thrust belt. Journal of Structural Geology 33 51-58.