Science Alert October 17, 2022
Within extreme continental extension areas, ductile middle crust is exhumed at the surface as metamorphic core complexes. A team of researchers in the US (Columbia University, Stony Brook University, University of Houston, Purdue University) developed a general model for metamorphic core complexes formation and demonstrated that they resulted from the collapse of a mountain belt supported by a thickened crustal root. They showed that gravitational body forces generated by topography and crustal root caused an upward flow pattern of the ductile lower-middle crust, facilitated by a detachment surface evolving into low-angle normal fault. This detachment surface acquired large amounts of finite strain, consistent with thick mylonite zones found in metamorphic core complexes. Isostatic rebound exposes the detachment in a domed upwarp, while the final Moho discontinuity across the extended region relaxed to a flat geometry. According to the researchers their work suggests that belts of metamorphic core complexes are a fossil signature of collapsed highlands…read more. Open Access TECHNICAL ARTICLEÂ
Schematics of the main mechanisms responsible for formation of the metamorphic core complexes… Credit: Nature Communications volume 13, Article number: 5646, 2022Â