Las formaciones Plio-Cuaternarias de El Abalario, en el litoral de la provincia de Huelva

Abstract

IntroducciónEl Abalario es el relieve litoral que queda limitado entre las poblaciones costeras onubenses de Mazagón al oeste y Matalascañas al este, y se extiende hacia el interior hasta el valle de La Rocina ( fig. 1) En conjunto forman una potente sucesión de más de 250 metros de espesor, de estructura ligeramente inclinada y de espesor creciente hacia el sureste. Sólo algunos sondeos de la parte occidental de El Abalario alcanzan las margas miocenas. En el resto del área de El Abalario, las margas están a una profundidad desconocida, por debajo de los sondeos más profundos. Sobre ellas se disponen gradualmente los depósitos arenosos de la Fm. Huelva, sin ninguna apreciable ruptura sedimentaria. Hacia el norte, la parte superior de la Fm. Huelva grada lateralmente a los depósitos arenosos de la Fm. Bonares, principalmente desarrollada fuera del área de estudio. Ambas formaciones quedan cubiertas por los sedimentos clásticos más gruesos de la Fm. Almonte. Por encima se desarrollan las arenas de la Fm. El Abalario, que configuran el relieve actual. El estudio mejora el modelo geológico existente y la conexión de unidades con los sectores vecinos.Palabras clave: Litoestratigrafía, Sedimentología, Plioceno, Cuaternario, Bajo Guadalquivir. ABSTRACTThe study of new and ancient boreholes in El Abalario area (Lower Guadalquivir basin) permitted to identify four main plio-quaternary formations above the Miocene marls, namely: Huelva Sands, Bonares Sands, Almonte Sands and Gravels, and El Abalario Sands. Respectively, they are interpreted as shallow marine, deltaic, alluvial and eolian sediments, together forming a marine to continental sequence that reaches a thickness of more than 250 metres. All sediments are arranged as a gentle dipping and thickening structure to the southeast. Only a few boreholes of the western border of El Abalario reach the top of the Miocene marls. In the rest of the Abalario area the Miocene marls are confined to an unknown level bellow the deepest boreholes. Upward, the marls grade to the Huelva sands, without any appreciable break in the sediments. To the north, the upper part of the Huelva formation grades to the Bonares sands, which is mainly developed outside the study area. Both formations are covered by the coarse clastic deposits of the Almonte formation. At the top, El Abalario sands recover all previous deposits and configure the current relief. This study improves the early existing geology profile and the connection with the surrounding areas.

Applying 3D Geostatistical Simulation to Improve the Groundwater Management Modelling of Sedimentary Aquifers: The Case of Doñana (Southwest Spain)

“…Comparing the results with the interpretations by Salvany [34,54], the simulation was validated by both hydrofacies proportions and facies distribution ( Figure 6). The proportions were 25% (Hydrofacies 1, Aeolian and dune sands), 2% (Hydrofacies 2, silt basin), 12% (Hydrofacies 3, sand basin), 15% (Hydrofacies 4, marshlands clays), 24% (Hydrofacies 5, clay, sand and gravel), and 22% (Hydrofacies 6, sand and gravel).…”

Evidence-based Risk Assessment of Ecological Damage due to Groundwater Abstraction; the Case of Doñana Natural Space, Spain

“…Zahíllo . The aeolian aquifer sits on top of the detritic aquifer (Salvany et al 2010); hydro-geological modelling has demonstrated interaction between the two aquifers at Los Sotos (Juárez et al 2012) and there is some minor interaction near Charco del Toro, but the full extent of aquifer connectivity is uncertain. The aeolian aquifer is recharged predominantly by local winter rainfall (Molano-Leno et al 2018) with 64% finding its way into the aquifer (Kohfahl et al 2019b).…”

The Origin and Evolution of Late Holocene Tsunamiites in the Doñana National Park (SW Spain): Trace Elements as Geochemical Proxies

“…and Mesozoic-Cenozoic external zones (mainly clays, gypsum and carbonates); and the Neogene depressions, the most important of which is the Guadalquivir river Basin. Near the mouth of this river, six main formations are defined (Figure 1b) [13][14][15]: (i) the Gibraleón Clay Formation, monotonous lithofacies consisting of marine gray-blue marls and clays; (ii) the Huelva Sand Formation, with massive bioturbated sandy beds interbedded with lumachellic layers of marine mollusc shells; (iii) the Bonares Sand Formation, with basal, bioturbated coarse-grained sands and conglomerates near the top; (iv) the Almonte Formation, with alluvial sands and gravels; (v) the Alluvial Unit, with fluvial gravels and conglomerates; and (vi) El Abalario Formation, formed by aeolian sands.…”