Uplifting mountains and shaking deserts: volcano-tectonic earthquakes revealed by soft-sediment-deformation structures in Upper Cretaceous aeolian deposits
Author:
Alessandretti Luciano1, Warren Lucas V.2, Varejão Filipe G.3, Rassi Raul1, Dos Santos Maurício G.M.4, Silva Mariana N.M.1, Honorato Fernando R.1, Estrada Michele J.T.1, Cunha João V.O.1
Affiliation:
1. 1 Instituto de Geografia, Universidade Federal de Uberlândia, LMG-746 Km 1, 38500-000, Monte Carmelo, MG, Brazil 2. 2 Instituto de Geociências e Ciências Exatas, Departamento de Geologia, Universidade Estadual Paulista, Avenida 24-A, Bela Vista, 178, 13506-900, Rio Claro, SP, Brazil 3. 3 Departamento de Geologia, Escola de Minas, Universidade Federal de Ouro Preto, Morro do Cruzeiro, 35400-000, Ouro Preto, MG, Brazil 4. 4 Centro de Engenharia, Modelagem e Ciências Sociais Aplicadas, Universidade Federal do ABC, Avenida dos Estados 5001, Bangu, Santo André, São Paulo, Brazil
Abstract
ABSTRACT
During the last stages of Gondwana fragmentation, large regions of the newly formed South American continent were covered by extensive deserts. Some parts of this continental landmass were synchronously affected by pronounced tectonism and magmatism, which were responsible for reshaping the regional topography. In this context, the southwestern part of the Sanfranciscana Basin in central Brazil is a key area for understanding this particular period in the geodynamic evolution of the South American continent. Aeolian deposits of the Posse Formation in the basin occur in direct association with volcanic rocks of the Upper Cretaceous Mata da Corda Group. Here, we report evidence of synsedimentary magmatism in direct association with soft-sediment-deformation structures, including flame structures, load casts and pseudonodules, water-escape structures, convolute lamination, faults, breccias, and clastic dikes, developed exclusively in aeolian sandstone and siltstone facies. The deformation features are interpreted as indicative of liquefaction, fluidization, and brittle behavior of the loose to partially lithified, wet sandy–silty sediments. The Late Cretaceous aeolian sedimentation is contemporaneous with the uplift of the Paranaíba High and associated magmatism in the Minas–Goiás Alkaline Province. In this context, these significant volcano-tectonic activities are considered to have triggered ductile to brittle deformation in the reported aeolian deposits.
Publisher
Society for Sedimentary Geology
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