Effect of predeformational basin geometry in the kinematic evolution of a thin‐skinned orogenic wedge: Insights from three‐dimensional finite element modeling of the Provo salient, Sevier fold‐thrust belt, Utah

Abstract

[1] In fold-thrust belts, sedimentary cover rocks are detached from undeformed basement and undergo crustal-scale shortening and internal deformation. We have investigated a three-dimensional (3-D), nonlinear, elastic-plastic finite element model using the restored Provo salient of the Sevier belt as our initial configuration. In the model the deformed sedimentary prism displays large-scale geometries that are seen in many natural fold-thrust belts (e.g., arcuate salient, wedge-shaped cross section) and kinematics that are compatible with observations in the internal and external portions of the Provo salient; these suggest that the model can be used to predict geologic information that is generally not available from detailed observational studies in natural fold-thrust belts (e.g., strain history, material displacements, stress conditions). The model results indicate symmetric, noncoaxial, plane strain paths with consistent stress and strain orientations and material displacement directions in the middle of the 3-D wedge, and fully 3-D, nonsymmetric, noncoaxial, nonplane strain paths with out-of-transport material displacements over the lateral boundaries. The results from test runs further suggest that oblique ramps with strike direction less than 20°from the regional transport direction behave like lateral ramps, and those with strike direction greater than 80°from the regional transport direction behave similar to frontal ramps. Oblique ramps with dips greater than 60°behave like tear faults. These variations in different parts of the wedge are caused mainly by interaction between the transport parallel motion of the moving wedge and the preexisting footwall template of ramps and flats that the wedge has to ride over during its evolution.Citation: Kwon, S., G. Mitra, and R. Perucchio (2007), Effect of predeformational basin geometry in the kinematic evolution of a thin-skinned orogenic wedge: Insights from three-dimensional finite element modeling of the Provo salient, Sevier fold-thrust belt, Utah,

Two‐ and three‐dimensional numerical simulations of the stress field at the thrust front of the Northern Apennines, Italy

“…This is consistent with the fact that Sh min orientations, differently from the general trend, here become parallel to the direction of regional shortening. Such a rotation is consistent also with what predicted by our 3‐DMIRA model after the slip of the fault and is in line with the results of 3‐D numerical models dedicated to other regions, showing that lateral variations in the geometry of active structures control the present‐day state of stress [ Hu et al , 1997; Kwon et al , 2007].…”

“…The geomechanical properties (Tables 2 and 3 assumed for each formation in the 2‐D models (Young's modulus, Poisson's ratio, density) were obtained from sonic compressional and shear, and bulk density logs [ Biot and Willis , 1957; Harrison et al , 1990] applying also the correction from dynamic to static Young's modulus and are consistent with values commonly used in the literature [e.g., Zhao et al , 2004; Chamlagain and Hayashi , 2007; Kwon et al , 2007]. Several simulations, not shown, were done varying the elatic parameters but no significant changes were obtained in the predicted stress field.…”

Penetrative Strain and Partitioning of Convergence‐Related Shallow Crustal Shortening, Across Scales, in the Lesser‐ and Sub‐Himalayan Thrusts: Insights From the Eastern Himalaya, Sikkim

“…Therefore, the strain ellipsoids are affected by the N‐S trending antiform, and the Y ‐axis exhibits the strongest lateral variation as compared to the X‐ and the Z ‐axes. Previous studies from various FTBs have shown that lateral variations in thrust sheet geometry at the regional scale, as manifested by salient‐recess pairs, can affect the strain ellipsoid geometry (e.g., Kwon & Mitra, 2004; Kwon et al., 2007; Mitra, 1997; Strine & Mitra, 2004). This study shows that even smaller scale lateral variation in the thrust geometry (∼15 km) can also affect and modify strain ellipsoid geometry of thrusts.…”

“…Additionally, the structures of orogens vary laterally (e.g., Bhattacharyya & Ahmed, 2016; Macedo & Marshak, 1999; Mitra et al., 2010). Although there are studies addressing strain variation at a larger‐scale, for example, salient‐recess pairs (Kwon & Mitra, 2004; Kwon et al., 2007; Law et al., 2010; Mitra, 1997; Strine & Mitra, 2004), effects of smaller‐scale along‐strike structural variation in thrusts on strain geometry and magnitude are not very well understood. Therefore, partitioning of convergence‐related shortening into major thrust sheets and penetrative strain within the corresponding thrust sheets, their spatial variations within the orogenic wedge, and contribution of penetrative strain into total shortening budget remain poorly understood.…”

Inheritance of Jurassic rifted margin architecture into the Apennines Neogene mountain building: a case history from the Lucretili Mts. (Latium, Central Italy)

“…A similar framework emerges also from a certain number of case histories in the Apennines and Sicily at various scales, especially from a geometric point of view, mainly based on 2D representations (cross-sections parallel to the tectonic transport direction: Tavarnelli et al 2004;Scisciani 2009 andDi Francesco et al 2010 for a review). Nevertheless, recently there has been growing attention towards 3D kinematic reconstructions of the evolution of non-cylindrical structures in fold-and-thrust belts through both numerical and analogue modelling (Corrado et al 1998;McClay et al 2004;Kwon et al 2007, and references therein).…”