Positive inversion of extensional footwalls in the southern Serra do Espinhaço, Brazil - insights from sandbox laboratory experiments

Abstract

Analogue experiments were carried out to get insights into the processes governing positive inversion during the foreland propagating thrust tectonics in the southern Serra do Espinhaço, a Brasiliano/Panafrican foldthrust belt in southeast Brazil. In particular, model listric half-grabens were inverted by applying contractional displacement to the footwall blocks. We investigated two different inversion conditions in listric half-grabens: (i) extensional and contractional detachments at the same level and (ii) at different positions. The models revealed that the development of a forward-breaking thrust system occurs in the basin synrift deposits, by contractional translation of the extensional footwall block when the extensional and contractional master faults do not coincide. Our experiments show the tectonic imbrication between basement and synrift sequences which characterizes the southern Serra do Espinhaço, and support the location in the eastern mountain range domain of the Espinhaço rift master fault system, which is not exposed at the surface.

The First Andean Compressive Tectonic Phase: Sedimentologic and Structural Analysis of Mid‐Cretaceous Deposits in the Coastal Cordillera, Central Chile (32°50′S)

“…The presence of roof pendants of the Veta Negra Formation (see cross section A‐A′ in Figure b) over the Caleu pluton, which was emplaced at 7 km depth (Parada et al, ), and the fact that some of the highest ridges (>2,000 m of altitude) of the Coastal Cordillera in this region consist of the Veta Negra Formation suggest that the structural style of the region can be related to inversion of a former extensional basins that accommodated the Early Cretaceous volcanics. Furthermore, similar features to those observed in the asymmetric, long‐wavelength Cerro Blanco Anticline with a tight hinge and a steep frontal limb onlapped by growth strata have been reconstructed in analogue modeling experiments for the inversion of synrift sedimentary piles along a steep west dipping positively inverted listric fault (Gomes et al, ; McClay & Buchanan, ; Yamada & McClay, ).…”

Analogue modelling of basin inversion: a review and future perspectives

“…In these models, a plastic sheet between the basement block and the model materials is connected to a moving sidewall or backstop so that the outward motion of the sidewall caused normal faulting above the footwall block. The resulting rift structures are subsequently inverted by moving the sidewall inward again (Mc-Clay, 1989Buchanan and McClay, 1991;Mitra 1993;Mitra and Islam, 1994;Gomes et al, 2006Gomes et al, , 2010. Alternatively, one can also move the footwall block itself (Yamada and McClay, 2004;Ferrer et al, 2016), which is however mostly a change of reference frame (see discussion in Zwaan et al, 2019).…”

“…In addition to top-view photography, model set-ups with transparent sidewalls enable direct monitoring of model deformation at the sides of the experiment (Koopman et al, 1987;McClay, 1989McClay, , 1995Buchanan and McClay, 1992;McClay and Buchanan, 1992;Gomes et al, 2006Gomes et al, , 2010Jagger and McClay, 2016;Lebinson et al, 2020, Fig. 7b).…”

Registro e análise de estruturas relacionadas com a tectônica extensional do rifteamento Macaúbas na Serra Central, norte de Minas Gerais

“…Aqui é empregada a proposta de uma geometria em hemigráben conforme interpretado por Hercos et al (2008) e Danderfer (2000 para o Espinhaço Meridional e Setentrional, respectivamente, para explicar a deposição do Grupo Macaúbas e o basculamento das camadas do Supergrupo Espinhaço (Figura 8B). Essa geometria varia em função do mergulho da borda de falha principal, a qual, posteriormente, teria controlado o processo de inversão e encurtamento das camadas no interior da bacia (p.ex., Danderfer, 2000;Gomes et al, 2006;Yagupsky et al, 2008).…”