FacebookFlickrYouTube
Divulgazione e didattica
Sei qui: Home > News > How brittle detachments form and evolve through space and time

How brittle detachments form and evolve through space and time

PUBBLICATO: 9 Dicembre 2024
Earth and Planetary Science Letters, Zuccari et al. (2024) - Fig. 8
Figure 8. Time-constrained model for brittle detachments evolution. (A) crustal thinning, hinge rolling and brittle-ductile detachment zones initiation. (B) Deformation localisation along the main brittle detachment, gouge formation and development of SC structure-dominated shear zone, coeval with the onset of ductile deformation along the upper part of the exhuming granite. (C) Down-dip deformation migration by cataclasis and gouge formation in the deep part of the brittle detachment coevally with the development of ultramylonites along the basal ductile detachment. (D) Protracted deformation and extreme localisation during the final stages of the granite exhumation. Late brittle overprint on the early ductile fault architecture after the complete exhumation of the granite.

Zuccari C., F. Mazzarini, E. Tavarnelli, G. Viola, L. Aldega, V. Moretto, R. Xie, G. Musumeci, (2024). Earth and Planetary Science Letters, 648. https://doi.org/10.1016/j.epsl.2024.119108

Abstract

We report the first absolute deformation ages for the Mykonos Detachment that juxtaposes, in the context of the current Aegean rifting, Miocene siliciclastic deposits in the hanging wall against metabasites and synkinematic granites in the footwall. We identified and characterised 16 brittle structural facies (BSFs) within the detachment fault architecture through fieldwork, optical microscopy, and X-ray diffraction. BSFs dating by K-Ar of synkinematic mixed layer illite-smectite shows that the preserved BSFs formed during repeated slip events, thus constraining protracted faulting between 13.5 and 6.5 Ma. Dating, structural and mineralogical characterisation allowed for the time-constrained evaluation of the activation/de-activation of the involved deformation mechanisms and of the processes, including (i) fault zone nucleation, (ii) deformation partitioning, (iii) cataclasis, gouge formation and (iv) the final deformation localisation, that govern the evolution of brittle detachments, shaping the local current upper crustal structure. Our results provide new insights into the understanding of wide active and fossil rift systems.

Accessibility by WAH