Complex geometry and kinematics of subsidiary faults within a carbonate-hosted relay ramp

Abstract

Minor fault geometry and kinematics within relay ramps is strongly related to the stress field perturbations that can be produced when two major fault segments overlap and interact. Here we integrate classical fieldwork and interpretation of a virtual outcrop to investigate the geometry and kinematics of subsidiary faults within a relay ramp along the Tre Monti normal fault in the Central Apennines. Although the Tre Monti fault strikes parallel to the regional extension (NE-SW) it shows predominant dip-slip kinematics, suggesting a NW-SE oriented extension acting at subregional scale (1-10 km). Conversely, the slickenlines collected on the front segment of the relay ramp highlight right-lateral kinematics. The subsidiary faults in the relay ramp show a complex geometry (variable attitudes) and slickenlines describe multiple kinematics (left-lateral, dip-slip, right-lateral), independently of their orientation. Our fault slip analysis indicates that a local stress field retrieved from the kinematic inversion of the slickenlines collected on the front segment, and likely promoted by the interaction between the overlapping fault segments that bound the relay zone, can explain most of the geometry and kinematics of the subsidiary faults. Further complexity is added by the temporal interaction with both the regional and sub-regional stress fields.

Review of Modeling Approaches to Groundwater Flow in Deformed Carbonate Aquifers

“…The direction of such tectonic structures is less spatially consistent than fold axis in thrust belts at the scale of a few to up to several kilometers. This structural pattern is related to linkage of non-subparallel normal faults (Soliva and Benedicto 2004;Mercuri et al 2020). Similarly, normal faults show variation of up to approximately 40 • in their trends in areas where uplift-generated joints are mapped in fractured limestones (Gillespie et al 2001).…”

“…As a consequence, hydraulic conductivity tends to be higher parallel to the fold axis (Figure 3a). The orientation of folds axis can be considered constant at the scale of approximately 0.5-5 km according to geological maps in folded areas (Santantonio et al 2017;Mercuri et al 2020). At this spatial scale of a few kilometers, contaminant plumes are constrained by geophysical monitoring at industrial field sites (Chapman and Parker 2005;Parker et al 2008).…”

“…Notably, large-displacement (throw > ∼100 m) normal faults in limestones and dolostones are also characterized by up to 40 • change of trend in geological maps. This structural characteristic is related to the linkage of neighboring and nonparallel normal faults that occur in carbonate rocks at a variety of scales (Dawers and Anders 1995;Mercuri et al 2020). From a geomorphological point of view, normal faults are frequently associated with cavities, karsts, and dolines with principal axes sub-parallel to the fault plane in carbonate rocks (Kresic 1995;Göppert et al 2011;Pepe and Parise 2014).…”

Low‐Angle Shear Within the Exposed Mânzălești Diapir, Romania: Salt Decapitation in the Eastern Carpathians Fold‐and‐Thrust Belt

“…During recent years, the use of photogrammetry has become a key component of fieldwork in geosciences (i.e., Adamuszek et al, 2021;Fernandez et al, 2021;Mercuri et al, 2020;Weismüller et al, 2019). Tools for interpreting three-dimensional (3D) outcrops in Digital Outcrop Models (DOM) are emerging, and extracting structural data from outcrops that are not easy or safe to reach is now possible.…”

Microstructure and fluid flow in the vicinity of basin bounding faults in rifts – the Dombjerg Fault, NE Greenland rift system

“…1b, 2). In such a rightstepping setting, local stress perturbation and clockwise re-orientation of the principal stress axes is common (e.g., Çiftçi and Bozkurt, 2007;Rotevatn and Bastesen, 2012;Mercuri et al, 2020), which may explain the overall trend of the veins. However, the setting is complicated by the circumstance that the majority of the veins formed in the post-rift stage in the Aptian/Albian and it is inferred that the vein ages also reflect the time of fracturing (Salomon et al, 2020).…”