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
4 results
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Now showing 1 - 4 of 4
Item Holocene floods in a complex fluvial wetland in central Spain: Environmental variability, climate and time(Global and Planetary Change, 2019) Santisteban Navarro, Juan Ignacio; Mediavilla, Rosa; Galán de Frutos, L.; López Cilla, IgnacioThe study of flooding can be complex as it involves dynamic systems (rivers) characterized by high variability in time and space. To minimize the effects of these handicaps, we merge several records from different locations across the hydrographic basin of the Upper Guadiana River (central Spain) and use multiple proxies. The comparison of three nearby cores by means of the facies, stratigraphic correlation and geochemical indexes allows us to differentiate local environmental changes related to the natural behaviour of the system (autocyclic) from those driven by external forcings (allocyclic). The facies and facies sequence analyses allow long-term paleohydrological trends to be reconstructed and parameters that are used to identify flooding events to be determined. Si (proxy for siliciclastic supply) and Ca/S (proxy for water budget/level) show trends that can be related to facies sequences and long-term variations. Si/Al is used as a sorting proxy (transport efficiency). To analyse the relative changes in sediment discharge and transport efficiency, these proxies are compared with water budget level, represented by (Si/Al)/(Ca/S) (sorting vs. water level) and Si/(Ca/S) (siliciclastic discharge vs. water discharge). We were able to define local, major and minor regional flood events/periods and events by relating sequence boundaries to the occurrence of environmental conditions related to high energy events (relative/absolute sorting, water level, sediment discharge) across multiple cores. Comparison to other studies around the western Mediterranean basin allows us to identify common periods of flooding at 9000–8400 cal. BP, 7700–7100 cal. BP, 6400–6200 cal. BP, 4900–3700 cal. BP, 3500–3300 cal. BP, ca. 2600 cal. BP, ca. 2000 cal. BP, ca. 1500 cal. BP and 1000–300 cal. BP. For the long-term evolution, it seems that changes in insolation during the Holocene could have played a role in controlling the hydrology. However, determining the drivers of higher-frequency variation is more challenging due to uncertainties in the chronologies and local differences. Nevertheless, some degree of correlation among these flooding periods and higher frequency changes in irradiance, temperature and NAO is observed.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 Model of Pleistocene geomorphological evolution in active Alpine neotectonics controlled margins in the western Mediterranean area: The case of SE Iberian Peninsula(Continental Shelf Research, 2024) Torres, Trinidad; Ortiz Menéndez, José Eugenio; Mediavilla, Rosa; Santisteban Navarro, Juan Ignacio; Blázquez, Ana; Sierro, Francisco Javier; Sánchez-Palencia, Yolanda; ópez Cilla, Ignacio; Vega, Rogelio de laAt the northern tip of the Betic realm (SE Iberian Peninsula), some troughs (synclines) and elevations (anticlines) alternate, marking the present-day coastal lobed morphology of cape-bounded bays, where subsidence and uplift conditions prevailed, respectively. In this study, we were able to establish a clear coastal evolution. To this end, we considered the sedimentological and palaeoenvironmental conditions, the palaeogeographical reconstruction, and recent tectonics until Middle Pleistocene times (MIS 5) through the interpretation of onshore cores, raised marine deposits and geophysical profiles. In this regard, as reflected by both onshore and offshore information, there seems to be a stratigraphical gap from the end of the Pliocene to MIS 15 (Middle Pleistocene). In areas under uplift conditions, linked to tardive Alpine tectonics, the deposits of ancient shorelines and raised beaches were located at different post-depositional elevations, which were dated from odd MIS 15 to MIS 5 using amino acid racemization. Only deposits aged MIS 7 and MIS 5 are roughly at the present-day sea level or some meters above. In the troughs, which remain mostly as lagoons and salt marshes, subsidence did not allow the sedimentary record to be discerned. However, many borehole cores were recovered, attesting lagoonal, marsh, sabkha, or alluvial environmental conditions, which were usually unconnected from the sea. Micropaleontological and amino acid racemization dating revealed these cores to be of MIS15 to MIS5 age. Offshore seismic research revealed five erosive-bounded deposits that are stacked accretionary prisms corresponding to highstands between odd MIS 15 and MIS 5. In contrast, even MISs can be correlated to the erosive horizons that separated the seismic units, reflecting lowstands. In this regard, some bars, at a range of distances from the present-day coastline, protected wetlands from marine influence, allowing the development of diverse sub-environments under changing paleogeographical and paleoclimatological conditions.Item Sedimentación mixta (siliclásticoscarbonatada) en lagos someros de baja pendiente con dominio del oleaje. Un ejemplo del Mioceno de la Cuenca del Duero(Limmogeology in Spain: a tribute to Kerry R. Kelts, 2003) Mediavilla, Rosa; Santisteban Navarro, Juan Ignacio; Dabrio González, Cristino José; Valero-Garcés, Blas L.Laeustrine deposits of Tecto-Sedimentary Unit N3 (Mediavilla et al., 1996) outcropping at the centcr of the Duero River Basin contain both, siliciclastic and carbonate formations. The siliciclastic formations were deposited in floodplain (oehre sands and muds), swamp (black and green muds) and lacustrine (green sands and muds) environments, and the carbonates (marls and massive, laminated, and cross-stratified limestones) are of Iacustrine origino Sequential analysis of these deposits reveals that both were coeval and formed in a single lakc. Their occurrence was a function of the distance of the sedimentation area to the siliciclastic sources. This model is ao altemative to their interpretation as an alternation of lithologieally different lakes. Therefore, the sedimentary sequenee can be interpreted as paleogeographically more than climatically controlled. This alternative interpretation urges for the use of correlations based on sequential analysis more than on Iithology for the study of sllch deposits.