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



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Martín Chivelet, Javier and Palma, Ricardo Manuel and López Gómez, José and Kietzmann, Diego A. (2011) Earthquake-induced soft-sediment deformation structures in Upper Jurassic open-marine microbialites (Neuquén Basin, Argentina). Sedimentary Geology, 235 . pp. 210-221. ISSN 0037-0738

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Penecontemporaneous decimetre-scale soft-sediment deformation structures are reported from the basal
part of the Upper Jurassic–Lower Cretaceous Vaca Muerta Formation, in the Malargüe–Las Leñas area of the
back-arc Neuquén Basin (Mendoza Province, Central Andes). The deformed interval (Amarillas bed) is only
0.3 to 0.9 m thick but occurs in a wide area, larger than 1500 km2. Its age, determined by ammonite
biostratigraphy, is Early Tithonian.
The soft-sediment deformation structures were generated in finely laminated, partially consolidated, organicrich,
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.
On the basis of the observed soft-deformation structures, their geographic distribution, their lateral
homogeneity, and the geodynamic framework of the 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 Neuquén back-arc basin.

Item Type:Article
Uncontrolled Keywords:Soft-sediment deformation, Seismites, Carbonate rocks, Tithonian, Back-arc basin, Andes
Subjects:Sciences > Geology > Stratigraphic geology
ID Code:20292
Deposited On:06 Mar 2013 13:37
Last Modified:11 Dec 2018 08:42

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