Earthquake-induced soft-sediment deformation structures in Upper Jurassic open-marine microbialites (Neuquén Basin, Argentina)

Abstract

Keywords:Soft-sediment deformation Seismites carbonate rocks Tithonian Back-arc basinThe soft-sediment deformation structures were generated in finely laminated, partially consolidated, organic rich, carbonate microbialites that were deposited in open-marine, poorly oxygenated settings, apparently devoid of any significant slope. Those structures include boudins of different sizes and complexity, a variety of folds, normal (listric) dm-scale faults, sub-horizontal detachment surfaces and other features, which are part of several larger-scale, complex slump structures. Deformation was dominantly plastic but near to the ductile-brittle field transition. AndesOn the basis of the observed soft -deformation structures, their geographic distribution, their lateral homogeneity, and the geodynamic framework ofthe basin in which it was generated, the Amarillas bed can be tentatively attributed to a large, intermediate-depth earthquake that occurred within the plate that subducted beneath the Andean continental margin and the Neuquen back-arc basin.

Sedimentology and stratigraphy of the Vaca Muerta Formation in the Cerro Domuyo area, Northern Neuquén, Argentina.

“…En este sentido, la facies de brechas intraclásticas que aparece en la base de la Formación Vaca Muerta se relaciona probablemente con la actividad sísmica del margen andino, antes que con factores autocíclicos del propio sistema depositacional. En efecto, Martín-Chivelet et al (2011) atribuyen la deformación del nivel microbiano basal de esta unidad con la actividad sísmica producida por terremotos de profundidad intermedia.…”

“…Sin embargo, el mecanismo disparador también puede asociarse a sobrepeso, deslizamientos o sismos (Molina et al, 1998). En efecto, Martín-Chivelet et al (2011) sugieren que la deformación del nivel microbiano basal de la Formación Vaca Muerta estaría asociada a actividad sísmica atribuida a terremotos de profundidades intermedias.…”

Seismites within Ordovician–Silurian carbonates and clastics of Southern Ontario, Canada and implications for intraplate seismicity

“…10CD). Breccias and small-scale folds are interpreted as the product of abrupt events that interrupted otherwise quiet-water lagoonal deposition of laminae (Calvo et al, 1998;Agnon et al, 2006;Martín-Chivelet et al, 2011). This involved in-situ liquefaction of laminae lying at and just below the seafloor to produce breccias; lateral slip is clearly indicated by folds and it is possible that breccias could record lateral flowage of liquefied slurries, but this cannot be clearly demonstrated by any characteristic internal flow fabric.…”

Seismites in the Dasheng Group: New evidence of strong tectonic and earthquake activities of the Tanlu Fault Zone

“…In the meantime, they undergo non-uniform vertical extrusion and lateral tension, which causes them to contract and expand in a non-uniform way, but they do not break down, giving rise to a pinch-andswell structure. When a pinch-and-swell structure is broken down or faulted by a microfault, a disconnected boudinage structure comes into being (Knaust, 2002;Martín-Chivelet et al, 2011;Tian et al, 2014). ball-and-pillow structure and pillow bed; 2. dike of liquefied sand and flame structure; 3. vein of liquefied sand and liquefied breccias; 4. boudinage structure; 5. syn-sedimentary fault; 6. filling structure of a seismic fissure; 7. giant conglomerates wedge; 8. seismically induced fold; 9. liquefied homogeneous layer and diapir structure; 10. layer number and type of associations of soft-sediment deformation structures (the main type is in the front of the secondary type); 11. ripple and cross-bedding; 12. seismic event; 13. geological observation point and strike and dip of rock layer; 14.…”