Browsing by Author "Gibert, L"

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    Late Miocene evaporite geochemistry of lorca and fortuna basins (Eastern Betics, SE Spain): evidence of restriction and continentalization
    (Wiley, 2020-09-26) García‐Veigas, J; Gibert, L; Cendón, DI; Artiaga, D; Corbí, H; Soria, JM; Lowenstein, TK; Sanz, E
    The Lorca and Fortuna basins are two intramontane Neogene basins located in the eastern Betic Cordillera (SE Spain). During the Late Tortonian—Early Messinian, marine and continental evaporites precipitated in these basins as a consequence of increased marine restriction and isolation. Here we show a stratigraphic correlation between the evaporite records of these basins based on geochemical indicators. We use SO4 isotope compositions and Sr isotopic ratios in gypsum, and halite Br contents to characterize these units and to identify the marine or continental source of the waters feeding the evaporite basins. In addition, we review the available chronological information used to date these evaporites in Lorca (La Serrata Fm), including a thick saline deposit, that we correlate with the First Evaporitic Group in Fortuna (Los Baños Fm). This correlation is also supported by micropalaeontological data, giving a Late Tortonian age for this sequence. The Second Evaporitic Group, (Chicamo Fm), and the Third Evaporitic Group (Rambla Salada Fm) developed only in Fortuna during the Messinian. According to the palaeogeographical scheme presented here, the evaporites of the Lorca and Fortuna basins were formed during the Late Tortonian—Early Messinian, close to the Betic Seaway closure. Sulphate isotope compositions and Sr isotopic ratios of the Ribera Gypsum Mb, at the base of the Rambla Salada Fm (Fortuna basin), match those of the Late Messinian selenite gypsum beds in San Miguel de Salinas, in the near Bajo Segura basin (40 km to the East), and other Messinian Salinity Crisis gypsum deposits in the Mediterranean. According to these geochemical indicators and the uncertainty of the chronology of this unit, the assignment of the Rambla Salada Fm to the MSC cannot be ruled out. © 1999-2024 John Wiley & Sons, Inc or related companies.
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    Palaeohydrological evolution and implications for palaeoclimate since the Late Glacial at Laguna de Fuente de Piedra, southern Spain
    (Elsevier, 2016-07-02) Höbig, N; Mediavilla, R; Gibert, L; Santisteban, JI; Cendón, DI; Ibáñez, J; Reicherter, K
    Here, we present a terrestrial multi-proxy record of Late Quaternary environmental changes in the southern Iberian Peninsula covering approximately 30 ka. This sedimentary record originates from a saline playa lake (Laguna de Fuente de Piedra) hosted within a complex geological setting dominated by Triassic claystones and evaporites, Jurassic carbonates and Miocene deposits leading to a complex hydrogeological setting. Dissolution of evaporites in the catchment and intense evaporation are responsible for saline waters fluctuating in the basin. Thus, salinity as palaeohydrological proxy, requires a decoupling of internal and external hydrogeochemical processes. The greatest accumulation of evaporites in the LFP late Pleistocene–Holocene record coincides with a more humid or, at least, less evaporative, period. Based on multi-proxy data we describe five lacustrine lithofacies (2–5), and fluvial deposits (1) from sediment cores. The proposed conceptual lake margin model contains three main lake water stages repeated within the sedimentary succession and building up the characteristic lithofacies. Lake water stages refer to a flooding stage (influx > outflux), high water stage (influx = outflux), and low water stage (influx < outflux). The lithostratigraphy reveals a palaeohydrological record suggesting climate changes and associated lake level fluctuations. Lake level oscillations of different amplitudes have been identified. Low amplitude changes have been revealed for the periods from 28 ka cal BP to 17.5 ka cal BP and from 8.2 ka cal BP to present, whereas in between (17.5 ka cal BP to 8.2 ka cal BP) the Late Pleistocene/Holocene transition shows high amplitude lake level changes. The latter coincides with an increased influence of saline subsurface waters, due to groundwater level rising (sulfate signature). In contrast, the Holocene, records the low amplitude oscillations and a drop of the groundwater levels, which creates a less saline or fresher footprint in the sediments (carbonate signature). Thus, the periods of low amplitude lake level oscillations, low inputs of clastics and low groundwater levels (drier) coincide with periods of minimal seasonal insolation difference. In contrast, the period of higher amplitude lake level oscillations, higher input of clastics and higher groundwater table (wetter) is correlative to periods of maximum difference between summer and winter insolation. © 2016, Elsevier Ltd and INQUA.