On the role of isostasy in the evolution of normal fault systems

Architecture and seismotectonics of a regional low‐angle normal fault zone in central Italy

“…The nucleation of the high-angle extensional splays and the related unloading would have migrated from west to east, and with the same polarity, the main fault plane would have gradually flattened consistently with the concept of a "rollinghinge" model [e.g. Buck, 1988;Wernicke and Axen, 1988] ( Figure 8). …”

Geologic, structural, and thermochronologic constraints on the tectonic evolution of the Sierra Mazatán core complex, Sonora, Mexico: New insights into metamorphic core complex formation

“…One model predicts many km of uplift via simple shear on vertical planes [e.g., Spencer, 1984;Wernicke and Axen, 1988]. Few if any structures within the footwall at Sierra Mazatán have been identified that might have accommodated such a deformation, particularly one of the required magnitude.…”

“…[74] Given the mechanical problems with initiating normal faults at shallow angles, many studies have emphasized isostatic flexural rotation of the footwall (i.e., the rolling hinge model) as a way to rotate steeply dipping faults to shallow orientations without requiring tilting via other normal faults [e.g., Buck, 1988;Wernicke and Axen, 1988;Spencer and Reynolds, 1991]. The growing acceptance of Figure 14.…”

“…The central issue in this long-standing debate is whether these normal faults initiated and slipped at their present shallow dips [e.g., Wernicke, 1981Wernicke, , 1985Scott and Lister, 1992] or formed at steep initial dips and were rotated to lower dips through time either by rotation on other normal faults [e.g., Proffett, 1977;Gans et al, 1985] or by isostatic rebound (rolling hinge) processes [Buck, 1988;Wernicke and Axen, 1988]. The initiation of lowangle normal faults is at odds with classic rock mechanics [Anderson, 1951] and slip on low-angle normal faults (<30°) is generally not supported by seismologic studies of actively extending regions [e.g., Jackson, 1987;Jackson and White, 1989].…”

Oceanic core complex formation, Atlantis Massif-oceanic core complex formation, Atlantis Massif, Mid-Atlantic Ridge: drilling into the footwall and hanging wall of a tectonic exposure of deep, young oceanic lithosphere to study deformation, alteration, and melt generation

“…If long-lived normal faulting and displacement are responsible for the evolution of the massif, uplift of the core may be the result of isostatic adjustment (Vening Meinesz, 1950) and thin-plate flexure (Spencer, 1985;Wernicke and Axen, 1988;Buck, 1988;Lavier et al, 1999). Differential rotation between the footwall and hanging wall blocks is predicted by thin-plate theory, so we can apply results from IODP Expeditions 304 and 305 to investigate whether the core-logging data show evidence of such history.…”