Person: Santisteban Navarro, Juan Ignacio
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First Name
Juan Ignacio
Last Name
Santisteban Navarro
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Geológicas
Department
Geodinámica, Estratigrafía y Paleontología
Area
Estratigrafía
Identifiers
7 results
Search Results
Now showing 1 - 7 of 7
Item Millennial-scale cycles of aridity as a driver of human occupancy in central Spain?(Quaternary International, 2016) Santisteban Navarro, Juan Ignacio; Mediavilla, Rosa; Celis, Alberto; Castaño, Silvino; Losa, Almudena de laHuman settlements around the fluvial wetland of Las Tablas de Daimiel (central Spain) have been related to the water availability in this area for nearly 5500 years; however the relationship of the hydrology of the wetland to climate change remains uncertain. Whilst archaeological and pollen data provide contradictory arguments, statistical empirical mode decomposition of geochemical data from core S-1 reveals arid periods ca. 1.8 cal. ka BP, ca. 3.3 cal. ka BP and ca. 5.5 cal. ka BP between which periods both Bronze Age and Iberian-Roman settlements developed. These periods can be identified in other records of the Iberian Peninsula and around the western Mediterranean. Comparison of these records points to a complex spatial pattern that evolved in time and, despite a number of forcings (volcanism, solar activity, atmosphere-ocean interactions) being invoked to explain such periods, there is no clear mechanism to explain their spatial pattern and the changes that have taken place since 2.5 ka BP.Item Late Quaternary stratigraphy of the La Janda Basin (SW Spain) - first results and palaeoenvironmental significance(Geophysical Research Abstracts, 2017) Höbig, Nicole; Santisteban Navarro, Juan Ignacio; Mediavilla López, Rosa María; May, Simon Matthias; Klasen, Nicole; Brückner, Helmut; Van’t Hoff, Jasmijn; Reicherter, KlausThe La Janda basin in southern Spain is a near-shore geo-bio-archive comprising a variable Quaternary depositional history, with shallow marine, lacustrine, palustrine, and terrestrial strata. In the 1930s the lake was drained and is serving now as a huge agricultural area. The 33 m-core recovered in fall 2016 along with several shallower drill cores up to c. 15 m, reveals insights into a unique mixed terrestrial palaeo-environmental archive in Andalucia influenced by the Atlantic Ocean and hence the North Atlantic Oscillation (NAO) within the Gulf of Cádiz. The basin's evolution was influenced both by the postglacial marine transgression and by an active tectonic fault controlling most of the accommodation space by causing subsidence. Our long core was accompanied by further corings along an E-W striking transect in order to reveal also the relation of the influence of tectonic activity with sedimentary sequences. Multi-Sensor Core Logging has been completed. Results of sedimentological, geochemical and micropalaeontological analyses will be presented in the frame of the climate variations during the Late Pleistocene and the Holocene, along with a preliminary age-depth model based on radiocarbon (AMS-14C) and optical stimulated luminescence (OSL) dating techniques. Our investigations ultimately aim at providing valuable information on major Late Pleistocene to Holocene climatic and palaeo-environmental fluctuations in the southernmost part of the Iberian Peninsula.Item Palaeohydrological evolution and implications for palaeoclimate since the Late Glacial at Laguna de Fuente de Piedra, southern Spain(Quaternary International, 2016) Hobig, N.; Mediavilla, R.; Gibert, L.; Santisteban Navarro, Juan Ignacio; Cendon, D.I.; 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 PleistoceneeHolocene record coincides with a more humid or, at least, less evaporative, period. Based on multi-proxy data we describe five lacustrine ithofacies (2e5), 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 ¼ 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.Item Cartografía de formaciones geológicas litológicamente similares en zonas llanas cultivadas(Ordenación del territorio y medio marino : V Reunión Científica de la Asociación Española de Teledetección Las Palmas de Gran Canaria 10,11 y 12 de noviembre de 1993, 1998) Riaza García, Asunción; Mediavilla López, Rosa María; Santisteban Navarro, Juan Ignacio; Cantón Garbín, ManuelLos estudios espectrales de laboratorio en el visible y el infrarrojo cercano (400- 2500 nro) sobre muestras de rocas de distintas formaciones geológicas detríticas siliciclásticas en una cuenca sedimentaria terciaria, sugieren que la proporción de carbonatos y su composición, así como la de la fracción arcillosa y la presencia de óxidos e hidróxidos de hierro, es responsable de las sutiles diferencias en las respuestas espectrales de las mismas. La presencia de cemento carbonatado en areniscas y conglomerados con cantos metamórficos y de costras carbonatadas intrasedimentarias facilita la expresión de distintas unidades en imágenes. Dos alteraciones ferruginosas cronológicamente sucesivas pueden distinguirse en las imágenes superpuestas a los demás acontecimientos geológicos. [ABSTRACT] The presence of carbonate of different composition, clays and iron oxides and hydroxides are responsible for the subtle differences on the spectral response of various geological units of tertiary age lithologically homogeneous, shown by laboratory spectra in the visible and the nearinfrared. Carbonate cernent in sandstones and conglomerate with metamorphic boulders, and intrasedimentary carbonate crusts favour the express ion of different units on the imagery. Two chronological stages of late fron alteration can be distinguished overlying prior geological events.Item Mapping geological stages of climate-dependent iron and clay weathering alteration on lithologically uniform sedimentary units using Thematic Mapper imagery (Tertiary Duero Basin, Spain)(International journal of remote sensing, 2000) Riaza García, Asunción; Mediavilla López, Rosa María; Santisteban Navarro, Juan IgnacioWeathering processes are responsible for slight surface mineralogical differences allowing the distinction between lithologically similar geological units using Thematic Mapper (TM) data. Two different stages throughout time of overlying iron alteration are notoriously distinctive on the imagery and laboratory spectra. Their diverse spectral behaviour follows the dominant iron hydroxide with kaolinite and carbonate crusts on the Pliocene Ochre Alteration typical of a humid warm climate, compared with the dominant nonhydratated iron oxides with smectite on the Miocene Red Alteration developed under a mediterranean dry climate. Iron materials with carbonate hinder appearance of the typical iron absorption features in the visible wavebands. Therefore, the iron weathering alteration coatings will be obscured on the imagery when it is developed on carbonate sediments or detritic sediments with carbonate cement or matrix. The presence of carbonate within the sediment as cement or alteration product decreases the overall reflectance of laboratory nonconsolidated rocks and the clay size fraction from rocks, apart from smoothing the 2200 nm absorption typical of OH-bearing minerals. The presence of carbonate cement and carbonate crusts favours the differentiation of some units. Digital mapping through image processing of different series of digital data leads to a sequential masking of classes to produce a final map. The sequence of masking produces different maps which can be used as a tool to model aspects of the sedimentary basin and geological processes throughout time.Item Geophysical characterization of stratigraphical surfaces: Basin floor and sedimentological architectural elements of Las Tablas de Daimiel (Quaternary of southern-central Spain)(Journal of Applied Geophysics, 2017) Rey, Javier; Martínez, Julián; Mediavilla López, Rosa María; Santisteban Navarro, Juan Ignacio; Castaño Castaño, Silvino; Losa, Almudena de laIn this paper we analyse and compare the efficiency of electrical resistivity imaging (ERI) and ground- enetrating radar (GPR) as tools for stratigraphic and sedimentological studies. To this end, we carried out borehole drilling and geophysical survey campaigns in two locations in Las Tablas de Daimiel area (Ciudad Real, Spain). In this region, the Quaternary record is build up by siliciclastic deposits (gravel, sand and silt) of fluvial origin and organic matter-rich sediments (peat, clay and silty clay rich in organic matter) and carbonates (biogenic deposits mainly made up of Characeae) deposited in fluvial wetland environments that rest on Ordovician quartzites and Pliocene karstified carbonates. Electrical resistivity imaging (ERI) supported by surface and subsurface (boreholes) lithological information allow to identify the geometry of the basement-Quaternary boundary in two areas. The morphology of this boundary is controlled by fractures and the karstification of the top of the Pliocene limestones. Thirteen GPR profiles (100 and 250 MHz antenna) provide information about the morphology and internal structure of the sedimentary units, down to 4 m below the surface. The observed features include: onlap of the sediments on the edge of the basin, fossilization of small paleo-reliefs by lacustrine deposits and channel fills in the Holocene deposits, and the sinking-collapse structures in the Neogene substratumItem Distribución y características de los depósitos fluviales pleistocenos del subsuelo de la Bahía de Cádiz(Geotemas, 2004) Mediavilla López, Rosa María; Antón López, Loreto; Dabrio González, Cristino José; Perucha, M.A.; Santisteban Navarro, Juan Ignacio; Mediato Arribas, José F.; Barnolas Cortina, A.; Llave, E.Middle to Upper Pleistocene fluvial sediments of the Cádiz Bay occur fifling partly two disconnected sub-basins excavated into shallow marine deposits of Pliocene to Lower Pleistocene age, and are buried under fluvial and estuarine Hofocene deposits. Subsurface, drill cores, and surface informatio indicate that the area of the Bay was occupied by a more or less continuous basin during the Late Pliocene-Lower Pleistocene, but the pattern changed during Middle to Late Pleistocene as revealed by facies analysis and palaeogeographical reconstruction of the fluvial environments. Fluvial deposits are laterally discontinuous, with variable rhickness and elongated troughs occupied by the coarsest sediments available. Our paleogeographical reconstruction for this periad shows a landscape with two subaerial sub-basins that acted as Fluvial valleys during glacially-forced lowstands, with two main Fluvial systems flowing constrained by topographical highs. This configurarion records the coincidence of very low sea level (regressive conditions) during glacial periods and active neotectonics. The valleys were flooded during the postglacial Holocene transgression and sea level surpassed the elevations separating the former valleys leading to the apparently simple configuration of the bay.