Person:
Santisteban Navarro, Juan Ignacio

First Name

Juan Ignacio

Last Name

Santisteban Navarro

URI

https://hdl.handle.net/20.500.14352/75187

Affiliation

Universidad Complutense de Madrid

Faculty / Institute

Ciencias Geológicas

Department

Geodinámica, Estratigrafía y Paleontología

Area

Estratigrafía

Identifiers

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Now showing 1 - 10 of 10

Holocene offshore tsunami archive – Tsunami deposits on the Algarve shelf (Portugal)
(Sedimentary Geology, 2023) Feist, Lisa; Costa, Pedro J.M.; Bellanova, Piero; Bosnic, Ivana; Santisteban Navarro, Juan Ignacio; Andrade, César; Brückner, Helmut; Duarte, João F.; Kuhlmann, Jannis; Schwarzbauer, Jan; Vött, Andreas; Reicherter, Klaus
The well-known 1755 CE Lisbon tsunami caused widespread destruction along the Iberian and northern Moroccan coastlines. Being affected by the powerful 1755 CE Lisbon tsunami, the southwestern Algarve shelf provides environments for detecting offshore tsunami imprints. Our multidisciplinary investigations (hydroacoustics, sedimentology, geochemistry, radiocarbon dating) of the Holocene sediments have revealed tsunami deposits linked to this tsunami and a ca. 3600 cal yr BP event. The latter event is until now unidentified in Portugal. Both event deposits contrast with the background shelf sedimentation by their coarser grain size, element composition, internal structure, and erosive base, making them discernible in the sub-bottom data and cores. Especially the ca. 3600 cal yr BP deposit is exceptionally well-preserved at one of the coring sites. The clear differentiation into several sections enables further insights into offshore tsunami transport and depositional processes. This study demonstrates that the record and preservation of tsunami deposits were possible on the Algarve shelf in specific locations sheltered from possible alterations. Our findings extend the tsunami catalogs of Portugal with a previously unknown tsunami dated to ca. 3600 cal yr BP.
Assessment of prospective geological hazards in Torrevieja-La Mata coast (western Mediterranean) based on Pleistocene and Holocene events
(Natural hazards and earth system sciences, 2021) Torres, Trinidad; Ortiz, José E.; Mediavilla López, Rosa María; Sánchez-Palencia, Yolanda; Santisteban Navarro, Juan Ignacio; Vega Panizo, Rogelio
The coastal zone in which the lagoons of La Mata and Torrevieja (Eastern Spain) developed can be described as a compilation of geo-hazards typical of the Mediterranean realm. This study has focused mainly on those linked to recent tectonics. Extensive use of the amino acid racemization dating method allowed us to establish the evolution of all the geomorphological units differentiated in the area, the most striking manifestation being at the La Mata Lagoon Bar, where MIS 5 deposits settled on MIS 7 sediments along a marked erosive unconformity, thereby attesting coastal uplift between these two stages. In addition, recent uplift processes were reflected on stepped abrasion platforms and, in some cases, enormous boulders were transported over these platforms by extreme surge waves. Furthermore, we obtained feasible evidence that, during the end of MIS 5, an earthquake with an offshore epicenter linked to Torrevieja Fault, Bajo Segura Fault or the set of faults linked to the former, was responsible for tsunami surge deposits represented in accumulations of randomly arranged and well-preserved Glycymeris and Acanthocardia shells. Recent catastrophic effects linked to the earthquakes were also detected. In this regard, comparison of the paleontological and taphonomic analyses allowed us to discern between wave and tsunami surge deposits. Therefore, evidence of these hazards undoubtedly points to important future (and present) erosive and/or catastrophic processes, which are enhanced by the presence of tourist resorts and salt-mining industry. Thus, these sites are also threatened by future increases in sea level in the context of warmer episodes, attested by raised marine fossil deposits. At the north of Cervera Cape, beaches will be eroded, without any possibility of sediment input from the starved Segura River delta. At the south of this cape, waves (and tsunamis) will erode the soft rocks that built up the cliff, creating deep basal notches.
Climate-Dependent Groundwater Discharge on Semi-Arid Inland Ephemeral Wetlands: Lessons from Holocene Sediments of Lagunas Reales in Central Spain
(Water, 2020) Mediavilla López, Rosa María; Santisteban Navarro, Juan Ignacio; López Cilla, Ignacio; Galán de Frutos, Luis; Hera Portillo, África de la
Wetlands are environments whose water balance is highly sensitive to climate change and human action. This sensitivity has allowed us to explore the relationships between surface water and groundwater in the long term as their sediments record all these changes and go beyond the instrumental/observational period. The Lagunas Reales, in central Spain, is a semi-arid inland wetland endangered by both climate and human activity. The reconstruction of the hydroclimate and water levels from sedimentary facies, as well as the changes in the position of the surface water and groundwater via the record of their geochemical fingerprint in the sediments, has allowed us to establish a conceptual model for the response of the hydrological system (surface water and groundwater) to climate. Arid periods are characterized by low levels of the deeper saline groundwater and by a greater influence of the surface freshwater. A positive water balance during wet periods allows the discharge of the deeper saline groundwater into the wetland, causing an increase in salinity. These results contrast with the classical model where salinity increases were related to greater evaporation rates and this opens up a new way of understanding the evolution of the hydrology of wetlands and their resilience to natural and anthropogenic changes.
Integrating current and historical water chemistry data with long-term piezometric records to develop a regional-scale conceptual flow model: Las Salinas spring, Medina del Campo, Spain
(Journal of Hydrology Regional Studies, 2021) Hera Portillo, África de la; López Gutiérrez, J.; Marín-Lechado, Carlos; Martínez Santos, Pedro; Ruiz-Constán, Ana; Corral Lledó, M. M.; Galindo Rodríguez, E.; Mediavilla López, Rosa María; Santisteban Navarro, Juan Ignacio; Rodríguez-Jiménez, Juan José; Callaú-Lópes, M.F.
Study region: Old Las Salinas spring in Medina del Campo, Duero river basin, central Spain. Study focus: Medina del Campo groundwater body (MCGWB) is a multilayer semiconfined aquifer subject to intensive pumping since the 1970’s, where the current existence of spas where there used to be traditional baths could confirm the existence of deep groundwater flow paths. The old spring of Las Salinas (OSLS) is a saline anomaly in an aquifer with predominance of CaCO3H waters whose occurrence has not yet been formally explained. Long-term geological, geophysical, hydrogeological and hydrochemical records were integrated and complemented with field work to clarify its existence. New hydrological insights for the region: Outcomes led to the conclusion that the hydrochemistry of the Olmedo and Palacio de las Salinas salt baths is associated with the existence of a major threshold in the impervious basement of the aquifer, which intercepted deep regional groundwater flow and caused upwelling to the surface under unperturbed conditions. These results allow for the development of a conceptual flow model at the regional scale that explains the changes in natural water chemistry that have been identified in recent decades.
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 la
At 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.
Environmental Changes and Cultural Transitions in SW Iberia during the Early-Mid Holocene
(Applied Sciences, 2021) Val-Peón, Cristina; Santisteban Navarro, Juan Ignacio; López Saez, José Antonio; Weniger, Gerd-Christian; Reicherter, Klaus
The SW coast of the Iberian Peninsula experiences a lack of palaeoenvironmental and archaeological data. With the aim to fill this gap, we contribute with a new palynological and geochemical dataset obtained from a sediment core drilled in the continental shelf of the Algarve coast. Archaeological data have been correlated with our multi-proxy dataset to understand how human groups adapted to environmental changes during the Early-Mid Holocene, with special focus on the Mesolithic to Neolithic transition. Vegetation trends indicate warm conditions at the onset of the Holocene followed by increased moisture and forest development ca. 10–7 ka BP, after which woodlands are progressively replaced by heaths. Peaks of aridity were identified at 8.2 and 7. 5 ka BP. Compositional, textural, redox state, and weathering of source area geochemical proxies indicates abrupt palaeoceanographic modifications and gradual terrestrial changes at 8.2 ka BP, while the 7.5 ka BP event mirrors a decrease in land moisture availability. Mesolithic sites are mainly composed of seasonal camps with direct access to the coast for the exploitation of local resources. This pattern extends into the Early Neolithic, when these sites coexist with seasonal and permanent occupations located in inland areas near rivers. Changes in settlement patterns and dietary habits may be influenced by changes in coastal environments caused by the sea-level rise and the impact of the 8.2 and 7.5 ka BP climate events.
Representation and biases: Pollen–vegetation relationships and their contribution to the study of fossil pollen records in SW Iberia
(Review of Palaeobotany and Palynology, 2023) Val-Peón, Cristina; Maié, Tiago; López Saez, José Antonio; Santisteban Navarro, Juan Ignacio; Mediavilla López, Rosa María; Reicherter, Klaus
In order to provide a better framework for the interpretation of fossil pollen records, a set of 49 modern pollen samples collected across different habitats of SW Iberia, categorised by context and sample type (soil vs moss), were selected to explore pollen–vegetation relationships by multivariate analysis and identify possible biases in pollen representativeness. The distribution of both samples and pollen taxa in the plots is successfully explained according to specific environmental variables in some clusters (A, B and E) in which plant communities depend on certain environmental conditions. On the other hand, other clusters (C, D and F) are better explained by opposition to some variables and suggest a wider range of adaptability of their floristic communities. The classification of samples by context consistently explains their differences in vegetal and environmental terms. However, some discrepancies seem to be better explained by sample type (soil vs moss), which raises some questions on how taphonomic factors may cause biases in both modern and fossil pollen samples.
Natural and anthropogenic processes in La Janda basin (SW Iberia) from the Late Pleistocene to the Mid-Late Holocene
(Continental Shelf Research, 2023) Val Peón, Cristina; López Saez, José Antonio; Santisteban Navarro, Juan Ignacio; Mediavilla López, Rosa María; Becerra, Serafín; Domínguez Bella, Salvador; Fernández Sanchez, Diego Salvador; Ramos Muñoz, José; Vijande Vila, Eduardo; Cantillo Duarte, Juan Jesús; Reicherter, Klaus
A multiproxy study (pollen, non-pollen palynomorphs, sedimentology, and geochemistry) was carried out in two cores drilled in La Janda basin (SW Iberia) to trace the environmental evolution and human impact on the landscape. An incised fluvial valley existed in the basin during the Late Pleistocene, followed by a transitional environment characterized by the development of saltmarsh vegetation affected by the increased marine influence ca. 10/8.7 ka cal BP. During this period comprising the Upper Palaeolithic and Mesolithic (>∼7.8 ka cal BP), the impact of hunter-gatherer groups on the landscape was rather low according to palynological and geochemical records. A restricted estuary connected to the sea was identified in La Janda between ca. 10/8.7-3.5/3.3 ka cal BP, coinciding with a predominance of saltmarsh vegetation developing on saline shore soils and the punctual presence of foraminifera and dynoflagellate cysts. The anthropogenic pressure was progressively increasing during the Neolithic, especially from ca. 7 ka cal BP, with markers suggesting herding/livestock activities prior to the punctual presence of cereals, which is only confirmed by the archaeological record ca. 6 ka cal BP. Human pressure become more noticeable throughout the Chalcolithic and Bronze Age (∼5-3 ka cal BP), period during which a new transitional phase is recorded in La Janda (ca. 3.5/3.3-1.3 ka cal BP), culminating in the terrestrialization of the area. The predominance of freshwater taxa and decrease of saltmarsh vegetation is observed during this period, and the transformation of the landscape for agricultural activities over the last centuries is reflected in the local presence of cereals and markers of erosive processes.
The transition from climate-driven to human-driven agriculture during the Little Ice Age in Central Spain: Documentary and fluvial records evidence
(Palaeogeography, Palaeoclimatology, Palaeoecology, 2021) Santisteban Navarro, Juan Ignacio; Celis, Alberto; Mediavilla López, Rosa María; Gil García, M. José; Ruiz Zapata, María Blanca; Castaño Castaño, Silvino
Knowledge about the relative impact of climate and socio-economic factors on agriculture is still not well known as they change in space and time. Social researchers stress the role of endogenous (societal, economical, etc.) factors whilst physical/natural scientists focus on the role of climate on land use and land cover change, but the latter do not usually focus on human dynamics. Through the analysis of proxies of land cover, sediment yield (erosion) and salinity changes from sediments in a fluvial wetland in central Spain and documentary evidence collected from the 16th century onwards, it becomes clear that climate impact on farming has changed during this period. Thus, until ca. 1725 CE, agriculture production in central-southern Spain followed the cycles and trends of rainfall at the annual, multiannual and decennial time scales. From that time onwards, production began to show discrepancies with climate, with high production cycles associated with dry periods being common and a sustained productivity that was independent of climate trends and it must be related to socio-economic changes. This change from climate-driven to human-driven agriculture can be seen in other areas of the Iberian Peninsula but at different times that vary from the first half of the 17th century until the first half of the 18th century. These different times can be attributed to diachronous changes in the Little Ice Age phases and local and regional differences in economic factors (such as proximity to commercial routes, development of markets) and their evolution, as supported by the different information sources.
Aridity events during the last 4000 years in Western Mediterranean marshes (Almenara and Benicasim marshes, E Spain)
(Quaternary International, 2020) Mediato Arribas, José Francisco; Santisteban Navarro, Juan Ignacio; del Moral González, Begoña; Dabrio González, Cristino José
Facies and geochemical analysis applied to marsh deposits are useful proxies for the reconstruction of aridity for the last millennia. The comparison of facies and geochemical records among cores from the Almenara and Benicasim marshes allows to identify changes in water level (Si/Al, Al, Ca) and salinity of the feeding waters (Mg/Al, Na/Al, S/Al). These changes, in turn, represent fluctuations in the position of the saline-fresh groundwater boundary, which can be related to variations in sea level and rainfall. For the last 4000 years, three events recording higher salinity conditions (ca. 3.4 ka BP, ca. 3 ka BP and ca. 1.8 ka BP) are noticeable in the record. Comparison to other studies around the Western Mediterranean basin allows us to correlate these events to arid episodes and to identify their forcing mechanisms. These aridity events are correlative to small falls in solar activity and Surface Sea Temperature (SST) during positive North Atlantic Oscillation (NAO) periods. Despite the small magnitude of these changes, the sensitivity of the system amplified the result providing a conspicuous signal.