La disolución de rocas evaporíticas : un importante factor geomorfológico en el Valle del Ebro

Calvo, Juan M. Tena; Collado, Juan Miguel A. Mandado; Vidal, Joaquin Rodrı́guez

doi:10.18172/cig.931

Cited by 3 publications

(4 citation statements)

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“…Gentle folds and warped structures in Miocene limestone formations resulting from the dissolution of underlying Neogene evaporites have also been reported in the Tajo Basin (Martin-Escorza 1976). Conspicuous examples of gravitational flexures are found in 51 the salt and gypsum bearing sequences ofRemolinos salt mine area in the Ebro Basin (Mandado et al 1984). Inthis area, the differential dissolution ofthe salt and gypsum beds gives place to disharmonic flexures and anarchic dips which tend to be directed towards the valleys (Fig.…”

Section: Figure4 Dissolutional'funnel(3om Indiameter) Developedinmiomentioning

confidence: 96%

The stratigraphical record and activity of evaporite dissolution subsidence in Spain

Gutiérrez

Ortı́

Gutiérrez

et al. 2001

Carbonates Evaporites

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The evaporite formations (in outcrop and at shallowdepth) cover an extensivearea of the Spanish territory. These soluble sediments are foundin diversegeological domainsand recorda widetimespan fromthe Triassicup to the presentday. Broadly,the Mesozoic and Paleogene formations (Alpinecycle) are affected by compressional structures, whereasthe Neogene (post-orogenic) sedimentsremain undefonned.The subsidence caused by subsurface dissolution ofthe evaporites (subjacentkarst)takesplace in three maintypes of stratigraphical settings: a) Subsidence affectingevaporite-bearing MesozoicandTertiarysuccessions (interstratalkarst);b) Subsidencein Quaternaryalluvialdeposits relatedto the exorheicevolutionofthepresent-dayfluvialsystems(alluvialor mantledkarst);c) Subsidencein exposedevaporites(uncovered karst). These types may be represented by paleosubsidence phenomena (synsedimentary and/or postsedimentary) recognizable in the stratigraphical record, or by equivalentcurrentlyactive or modemexampleswith surfaceexpression.The interstratal karstification of the Mesozoic marine evaporitesand the consequent subsidenceof the topstrata is revealedby stratiform collapsebrecciasand wedge-outs in the evaporitesgrading intounsoluble residues.InseveralTertiarybasins,the sedimentsoverlyingevaporiteslocallyshowsynsedimentary and/orpostsedimentary subsidencestructures. The dissolution-induced subsidence coeval to sedimentation gives place to local thickenings in basin-like structures with convergent dips and cumulative wedge out systems. This sinkingprocesscontrolsthe generation of depositional environments and lithofaciesdistribution. The postsedimentary subsidenceproducesa greatvarietyof gravitational deformations in the Tertiarysupra-evaporitic units includingbothductile and brittle structures(flexures, synfonns,fractures,collapseand brecciation).The Quaternary fluvial terrace deposits on evaporite sedimentsshow anomalous thickenings (>150 m) caused by a dissolution-induced subsidence process in the alluvial plain which is balanced by alluvial aggradation. The complex space and time evolutionpattern of the paleosubsidence gives place to intricate and anarchical structures in the alluvium which may be erroneously interpreted as pure tectonic deformations. The current subsidence and generationof sinkholes due to suballuvialkarstification constitutesa geohazardwhich affectsto largedenselypopulatedareas endangering human safetyand posinglimitationsto the development. An outstandingexamplecorresponds to Calatayud historicalcity, where subsidence severelydamageshighlyvaluablemonuments. The subsidenceresultingfrom the underground karstification of evaporiteshas determinedor influencedthe generation of some importantmodem lacustrinebasins like Gallocanta, Fuente de Piedra and Banyoles lakes. The suddenformationof sinkholes due to the collapse of cave roofs is relatively frequentin some evaporite outcrops. Very harmful and spectacularsubsidence activity is currently occurring in the Cardona salt diapir where subsidence has been dramatically exac...

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Section: Figure4 Dissolutional'funnel(3om Indiameter) Developedinmiomentioning

confidence: 96%

The stratigraphical record and activity of evaporite dissolution subsidence in Spain

Gutiérrez

Ortı́

Gutiérrez

et al. 2001

Carbonates Evaporites

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“…Another author claiming for an aeolian origin of gypsum silts is Quirantes (1978), who reported on the grain size of pure gypsum silts, similar to loess, and on their location on top of platforms South of Zaragoza and covering infilled valleys and leeward slopes in the area of Mequinenza. Indeed, Mandado et al (1984) indicated that gypsiferous silts were the residue of the weathering of gyprocks. They also pointed out that this term is confusing and conducive to errors, since it frequently refers to "gypsum silts interbedded in alternating gypsum deposits with alabaster gypsum nodules", which are actually nothing other than the products of the dissolution and alteration of the most porous and exposed gyprock facies.…”

Section: G E O L O G I C Amentioning

confidence: 99%

“…The weathering and pedogenetic processes on pure gyprock involve repeated dissolution and reprecipitation of gypsum in situ, giving rise to a mass of silt-sized (microcrystalline) and fine-sand gypsum that have a flourlike appearance in the field in the contact area with the gyprock outcropping surface (Artieda, 1996;Herrero, 1991;Herrero et al, 1992, Mandado et al, 1984. A gypsification process, involving a gypsum enrichment has been proposed (Herrero et al, 1992;Poch et al, 2018;Stoops and Ilaiwi, 1981).…”

Section: Genesis Of Flour-like Gypsummentioning

confidence: 99%

“…All these characteristics are not fulfilled by flourlike gypsum. Mandado et al (1984), Herrero (1991) and Artieda (2004) indicated that the formation of flour-like gypsum is associated with subaerial exposure of gyprock and subsequent weathering. These accumulations are also produced by processes of water capillary rise and evapoconcentration (Artieda, 1996;Poch et al, 1998), a common process for the formation of hypergypsic horizons e.g.…”

Section: Exclusion Of the Aeolian Origin For The Flour-like Gypsummentioning

confidence: 99%

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Silt-sized sediments and gypsum on surface formations in the Ebro valley. A disambiguation of the term gypsiferous silts

Poch¹,

Rodríguez‐Ochoa²,

Artieda³

et al. 2021

GeA

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Since the 60’s, many authors have reported the presence of common silt-sized materials in the Ebro valley, on surface formations and positions that have given rise to several interpretations, sometimes contradictory. According to the references, three main terms are used (gypsiferous silts, loess and flour-like gypsum) applied to silts and fine sands with gypsum accumulations. The two first terms are applied to materials with carbonate contents up to 40-50%, coarse silty to fine sandy textures, and located in different positions. Loess normally appears as thick outcrops on slopes leeward from the main wind direction, with a limited pedogenesis consisting of a partial carbonate mobilisation and gypsum contents between 0 and 30%. The third (gypsum-rich) type has a variable spatial distribution, appearing between limestone layers, along footslopes, outcropping as metric surface formations, or as generalized karstified subsurface accumulations. Their composition is almost 100% silt- to fine sand size lenticular gypsum. While some authors claim for an aeolian origin to all these materials, only part of them (loess) has a clear aeolian origin, while flour-like gypsum derives from on-site weathering of gyprock or by precipitation of calcium- and sulfate saturated watertables as it is reported to occur in many other arid regions; and the rest (gypsiferous silts sensu stricto) are mainly colluvial-alluvial. This distinction is necessary since they differ in their geotechnical behaviour and properties relevant for agricultural land uses, therefore they should be taken into account when carrying out geological mappings or soil surveys in this and similar arid regions.

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Geomorphology of the Tertiary gypsum formations in the Ebro Depression (Spain)

Elorza

Santolalla

1998

Geoderma

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La disolución de rocas evaporíticas : un importante factor geomorfológico en el Valle del Ebro

Cited by 3 publications

References 1 publication

The stratigraphical record and activity of evaporite dissolution subsidence in Spain

The stratigraphical record and activity of evaporite dissolution subsidence in Spain

Silt-sized sediments and gypsum on surface formations in the Ebro valley. A disambiguation of the term gypsiferous silts

Geomorphology of the Tertiary gypsum formations in the Ebro Depression (Spain)

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