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URI permanente para esta colecciónhttps://hdl.handle.net/10953/214

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3D geometry and architecture of a normal fault zone in poorly lithified sediments: A trench study on a strand of the Baza Fault, central Betic Cordillera, south Spain.
(Elsevier, 2019) Medina-Cascales, Iván; Koch, Leah; Cardozo, Néstor; Alfaro, Pedro; García-Tortosa, Francisco Juan
Successive excavation of 13 trenches of different orientations reveals the complexity of a normal fault zone in Pliocene-Pleistocene unconsolidated sediments on a strand of the Baza Fault, central Betic Cordillera, south Spain. These trenches and the excavation floor are interpreted and integrated to reconstruct the 3D geometry and internal architecture of the fault zone. The structure consists of two main fault strands: an eastern one with a few hundred metres throw and a western one with at least 15m throw. These strands interact and gradually merge to the south, bounding a main deformation zone narrowing from ∼7 to 1m along strike. Fault-bounded rock bodies, clay and sand smears, and clay injections define the structure. These features are highly variable in 3D. In the northern part of the outcrop, deformation is localized around the main strands, brittle in the west and more ductile to the east. As the strands and their fault zones increasingly interact, fault throw, rock deformation and maturity of the structure increase. Mechanical stratigraphy also controls the style of deformation. A realistic representation of this 4D picture of fault deformation is critical for modelling fluid flow in shallow to possibly deep, faulted sedimentary reservoirs.
Aboveground Carbon Fixation and Nutrient Retention in Temporary Spontaneous Cover Crops in Olive Groves of Andalusia
(FRONTIERS MEDIA SA, 2022-06-01) Torrús-Castillo, Milagros; Domouso, Pablo; Herrera-Rodríguez, José M.; Calero, Julio; García-Ruiz, Roberto
In Southern Spain, olive trees have traditionally been cultivated in marginal areas with relatively shallow and bare soils under rainfed conditions, resulting in heavy soil losses and soil degradation. The implementation of temporary spontaneous cover crops in the inter-rows of olive groves, has proven to be a suitable diversification strategy to reduce soil erosion but it can also contribute to climate change mitigation and the boosting of internal nutrient recycling. However, information on the contribution of cover crops to atmospheric CO2 fixation and on nutrient retention in olive groves is scarce, which is a major drawback when it comes to modelling on larger spatial scales. In this study, we aimed to assess the potential effects of temporary spontaneous cover crops in olive groves on CO2 fixation and nutrient retention. The aerial biomass of cover crops (0.25m(2) frames) and contents of carbon and nitrogen (CNHS analyser), phosphorus and potassium (IPC-MS) were analyzed in 46 commercial olive groves with different tree densities and cover crop layouts; the whole farm (WCC), the whole farm except the area below the tree canopy (CCC) or in bands of a given width in the inter-row area (BCC). Cover crops of 56% of the olive groves were under BCC whereas only 17% were under WCC. The annual net primary production of cover crops under WCC (1,707.4 kg DM ha(-1) y(-1)) was significantly higher than that of CCC (769.5 kg DM ha(-1) y(-1)) and with intermediate values for BCC (1,186.4 kg DM ha(-1) y(-1)). Similarly, the annual rate of C-CO2 fixation in the annual net primary production of olive groves with WCC (642.1 kg C ha(-1) y(-1)) was 1.35 and 2.1 times higher than the olive groves with BCC and CCC, respectively. On average, 19.5 kg N ha(-1) y(-1), 2.48 kg P ha(-1) y(-1) and 24.30 kg K ha(-1) y(-1) was accumulated in the biomass of the cover crops. This study demonstrates that cover crops contribute significantly to CO2 reduction and the retention of significant amounts of tree-unused nutrients. In addition, the higher the area covered by cover crops, the higher the contribution to these ecosystem services.
An integrated analysis (microfacies and ichnology) of a shallow carbonate-platform succession: upper Aptian, Lower Cretaceous, Betic Cordillera
(Springer, 2017-11-27) Nieto, L.M.; Reolid, M.; Rodríguez-Tovar, F.J.; Castro, J.M.; Molina, J.M.; Ruiz-Ortiz, P.A.
Four lithofacies and 12 microfacies types recognized in an upper Aptian section in the Sierra de Bedmar-Jódar (Prebetic of Jaén) represent shallow lagoonal environments (marl and marly limestone) and sand bars that delimited the lagoon. The lagoonal facies reflect subtidal restricted water circulation with low energy. The sand bar facies (intertidal environment) have upper surfaces that show the effects of supratidal and subaerial conditions. The presence of early fractures in particular lithofacies shows the importance of local synsedimentary tectonics during sedimentation. Thalassinoides, ?Arenicolites, Diplocraterion, Circolites, Gastrochaenolites and Trypanites are recorded in different beds of this section, reflecting various states of substrate consistency, in the form of firmground, hardground, and rockground. Whereas firmground conditions were dominant in the lower part of the section, hardgrounds and rockgrounds are mainly present in the upper part of the section. Four types of shallowing-upward elementary sequence are recognized. All the sequences show at the base mudstone or wackestone microfacies representing a lagoonal environment, overlain by sand-bar grain-pack-stone facies corresponding to a bar bounding the lagoon. The factors that controlled their development were carbonate production and tectonic movements.
Assessment of geodiversity at the confluence of different geological domains and delimitation of natural protected areas (examples from Southern Spain)
(Springer, 2023-06-24) Nieto, L.M.; Fernández, T.; Leiva-Lozano, J.E.
Geodiversity and biodiversity have been assessed in an area of the province of Jaén (Southern Spain), the first one from the consideration of partial indices based on lithology, geomorphology, pedology, hydrology, palaeontology, mineralogy and geosites; biodiversity is also regarded from previous data, considering a biodiversity index and endangered species index. This area shows the contact between the Guadalquivir Basin and the Betic External Zones. In addition, several natural protected areas have been defined, among which the Cazorla, Segura and Las Villas Natural Park (where mainly Prebetic materials outcrop) and the Sierra Mágina Natural Park (made up of Subbetic materials) stand out. The high and very high values of geodiversity have been located in an area where mainly Subbetic materials outcrop, including the Sierra Mágina Natural Park, and which coincides to a large extent with the front of the Betic External Zones and its contact with the Guadalquivir Basin. However, the Cazorla, Segura and Las Villas Natural Park is outside this area of high or very high geodiversity. Both natural parks fit well in areas where biodiversity and endangered species are important. These differences between the geodiversity values and the boundaries of these natural areas allow suggesting that, for delimitation of any natural protected area, its boundaries should be defined based on knowledge of the geodiversity and biodiversity of the region where the natural area is located.
Characterization of Wall Paintings of the Harem Court in the Alhambra Monumental Ensemble: Advantages and Limitations of In Situ Analysis
(MDPI, 2022-02-23) Arjonilla, Paz; Domínguez-Vidal, Ana; Rubio-Domene, Ramón; Correa, Elena; de-la-Torre-López, María José; Ayora-Cañada, María José
Non-invasive techniques (X-ray fluorescence, XRF, and Raman spectroscopy) were used for the study of the Hispano Muslim wall paintings. Principal component analysis (PCA) was performed on the semi-quantitative XRF results directly provided by the in-built factory calibrations with minimum user manipulation. The results obtained were satisfactory and highlighted differences and similarities among the measurement points. In this way, it was possible to differentiate the decorations carried out on gypsum plasterwork and the wall paintings over lime plaster. The color palette, revealed by combining the results from XRF and Raman spectroscopies, comprised the pigments hematite, lapis lazuli, cinnabar (in poor conservation state), and possibly, carbon. Evidence of past interventions was also provided by PCA on XRF data, which detected the presence of Pb, Ba, and Zn in some areas. Furthermore, the preparation layers have been studied in detail on crosssections of two microsamples. Several layers of lime plaster with a compact microstructure have been observed. The characteristic of the pictorial layer and the identification of calcium oxalate point to the use of a secco-technique. The main alteration identified was a gypsum surface layer covering the painting and signs of plaster deterioration due to gypsum migration to more internal areas. Finally, the comparison with the observations made by restorers in previous interventions on these paintings revealed the importance of the representativeness gained with the in situ study, which enabled the analysis of a high number of areas.
Clay saline diagenesis in lake Plio-Pleistocene sediments rich in organic matter from the Guadix-Baza Basin (Betic Cordillera, SE Spain).
(Elsevier, 2020-06-11) Jiménez-Millán, Juan; Abad, Isabel; García-Tortosa, Francisco Juan; Nieto, Fernando; Jiménez-Espinosa, Rosario
This study presents a mineralogical analysis of the effect of hypersaline lake environments rich in organic matter on the mineral transformations in sediments of the eastern part of the Guadix-Baza Basin (Betic Cordillera). Dark sediments with fragments of organic matter are rich in phyllosilicates (K-white mica, illite-smectite mixed layers, –I/S– minor amounts of paragonite, palygorskite, chlorite and kaolinite) and contain quartz, feldspars, and framboidal pyrite. X-ray diffraction patterns of I/S (R0 type, disordered) revealed a continuous between the positions of pure smectite and 30% of illite layers. Chemical composition of I/S mixed layers indicated a significant beidellitic substitution of Si by AlIV, Fe + Mg > 1 atoms per formula unit (a.p.f.u.) and K content up to 0.42 a.p.f.u. These data suggested the presence of a minor and variable amount of illitic layers among the major smectitic ones. Saline waters of the lake and the reducing environment of the sediment favored Mg and Fe2+ uptake, generating octahedral negative charge, which together with the beidellitic substitution would provide clay layer negative charge enough to admit K incorporation in the interlayer, hence the beginning of a diagenetic low temperature illitization.
Decorated plasterwork in the Alhambra investigated by Raman spectroscopy: comparative field and laboratory study
(Wiley, 2014-01-22) Domínguez-Vidal, Ana; de-la-Torre-López, María José; Campos-Suñol, María José; Rubio-Domene, Ramón; Ayora-Cañada, María José
This work presents the results of the study of plasterwork decorations located on the stalactite vaults of the Hall of the Kings in the Alhambra (Granada, Spain) by means of Raman micro-spectroscopy. Field investigations were carried out in situ using a portable Raman spectrometer during a conservation campaign in a completely non-invasive manner. In addition, taking into account the results obtained, a well-directed sampling was carried out to obtain complementary information by means of laboratory studies. Despite several practical problems during the non-invasive field studies (like difficulties for probe positioning and vibrations of the scaffolding), almost all the pigments present in the decorations of the Hall were identified using excitation at 785 nm: cinnabar, minium, carbon black, natural lapis lazuli and synthetic ultramarine blue. In addition, evidence of different degradation mechanisms of the red pigments was obtained in situ. On the contrary, the identification of blue-greenish and green pigments had to be performed on microsamples using a Raman microscope with excitation at 514 nm in the laboratory. In samples with blue and green areas, azurite severely degraded to clinoatacamite was identified. These were probably the remains of the oldest blue decorations. In addition, a technique for green decorations consisting on copper chlorides mixed with a small amount of lapis lazuli was identified. Other degradation products, identified in the laboratory regardless of the color of the pigment, were calcium oxalates. Finally, the laboratory studies also enabled the investigation of the stratigraphy of the pictorial layers. In this way, the presence of redecorations with overlaying layers of pigments even of different colors was revealed. Copyright © 2014 John Wiley & Sons, Ltd.
Does olive cultivation sequester carbon? Carbon balance along a C input gradient
(Elsevier, 2023-12) Torrús-Castillo, Milagros; Calero, Julio; García-Ruiz, Roberto
Currently, there are some initiatives aimed at transforming agriculture from being a source to a sink of greenhouse gases, mainly by encouraging combination of management practices that drive nature-based climate processes (NbCS) resulting in an increase in the stocks of soil and biomass organic carbon. Olive grove cultivation represents a key socio-economic and environmental asset for Mediterranean rural regions. Being a woody crop planted in an orchard fashion, the potential for organic carbon accumulation in the biomass and the soil is very high. In this study, farm, trees and soil carbon balances were analysed in 12 pairs of olive groves located in Southern Spain with different tree densities, age, varieties and irrigation regimens. One from each pair of the olive groves has applied (> 8 years) a combination of management practices that promote NbCS resulting in an increase in the entry of carbon, whereas the other comparable nearby olive grove has not implemented management practices that promote NbCS or C entries (non-NbCS). C balance at the farm level was mainly neutral or positive and averaged + 1.20 Mg C ha−1 y−1. However, C balance in the NbCS olive groves was 5 times higher than that of the non-NbCS. The mean soil C balances were negative (−0.18 Mg C ha−1 y−1; losing soil organic C) in the non-NbCS and positive (+1.48 Mg C ha−1y−1) in the NbCS olive groves thanks to the increase in the carbon entries due to the management practices which boost NbCS. This study highlights the important contribution of olive farming in mitigating climate change, which in turn would be an economic incentive for olive growers. Nonetheless, there is a high potential for improvement by implementing management practices which enhance nature-based processes such as the cultivation of temporary spontaneous cover crops and the application of shredded tree pruning and composted olive mill pomace and/or manure to the soil.
Does spontaneous cover crop increase the stocks of soil organic carbon and nitrogen in commercial olive orchard?
(Elsevier, 2024-12) Pareja-Sánchez, Evangelina; Calero, Julio; García-Ruiz, Roberto
Management practices in the inter-row area of olive orchards are undergoing significant transformations. Current regulations and recommendations are increasingly advocating the implementation of temporary spontaneous cover crops (TSCV) mainly to reduce erosion. Existing research has predominantly focused on evaluating the effectiveness of TSCV in mitigating soil erosion in olive orchards, with limited attention given to carbon (C) cycling, despite the potential of TSCV for contributing to the removal of atmospheric CO2 and in the reduction of eroded carbon. Moreover, the limited number of studies on the effects of TSCV on C cycling have been confined to a few experimental sites and at the short term. This study aimed to assess the potential of TSCV to enhance carbon sequestration and nitrogen retention in rainfed commercial olive orchards under semi-arid conditions. To achieve this, we evaluated the annual aboveground organic carbon input due to TSCV, as well as the stocks of soil organic (SOC) and inorganic (SIC) carbon and total N (STN) in 24 commercial olive groves with calcareous Regosols and calcium Cambisols as the predominant soil types that have implemented TSCV for at least the last 8 years. These were compared with 24 comparable groves with bare soil (BS). Net aboveground annual carbon and CO2 fixation of the TSCV averaged 125.7 kg C ha-1 y-1 and 460 kg CO2 ha-1 y-1, respectively, which are figures relatively low mainly due to the low area covered by the TSCV. After eight years of implementing TSCV, the SOC stocks increased by an average of 2.03 Mg C ha-1 (in the top 30 cm of soil) compared to BS olive orchards. Moreover, SOC content of unprotected (>250 μm) and physically protected (53–250 μm) fractions were 82 and 38 % higher in the TSCV olive farms. Although there was a tendency of lower SIC content in TSCV olive orchards, differences were not significant. The STN content and the potentially mineralizable nitrogen in TSCV farms were on average 26 % and 77 % higher than in BS olive orchards. These findings underscore the potential of TSCV for organic carbon accumulation and nitrogen retention in the soil, contributing to climate change mitigation and soil fertility enhancement. Increasing vegetation coverage and productivity can enhance their effectiveness.
Early development and OAE 1a-linked demise of a carbonate platform in the western Tethys: Lower Cretaceous of Sierra Mariola (South Iberian Paleomargin, SE Spain)
(Elsevier, 2024) Martínez-Rodríguez, R.; Castro, J.M.; de Gea, G.A.; Nieto, L.M.; Ruiz-Ortiz, P.A.; Skelton, P.W.
A carbonate platform succession of early Aptian age is described from the Sierra Mariola, which is located within the Prebetic Zone of the Betic External Zones (BEZ) of the Southern Iberian Palaeomargin, in SE Spain. The facies and stratigraphic architecture of the studied succession are described and analysed from multiple logged sections to characterize different depositional environments. The cyclic stacking of facies observed suggests a possible orbital forcing of climate transmitted to sedimentation. Superbundles are recognized describing two sequences of Regressive-Transgressive (R-T) evolution. Analysis of carbon-isotope data identifies both the interval before the hyperthermal event of the early Aptian Oceanic Anoxic Event (OAE 1a) and the onset of the latter event, with an abrupt change in sedimentation marking the demise of the carbonate platform. The field outcrop thus preserves a record of the transition from a greenhouse world to a hothouse event.
Environmental conditions in the pre-Jenkyns event time (late Pliensbachian - early Toarcian) in the South Iberian Palaeomargin (Betic External Zones, Southern Spain)
(Springer, 2024-10-18) Nieto-Albert, Luis Miguel; Ayadi, Chaima; Fraguas, Ángela; Molina-Cámara, José Miguel; Reolid, Matías
Three stratigraphic sections of the Betic External Zones were studied, two from the Median Subbetic (PEL and PR) and one from the External Subbetic (CE). The upper Pliensbachian materials and the transition to the lower Toarcian were dated with calcareous nannofossils in PEL and PR in this paper, while in the CE section, previous ammonite and nannofossil biostratigraphies were considered. The dominant facies are alternance of marly limestone—marl, although in the CE section, the Toarcian is represented by marls, where the Jenkyns Event has been recorded. In terms of ichnofossils, in the PEL section Macaronichnus predominates. In the PR and CE sections, the ichnoassemblages are dominated by Planolites, Thalassinoides and Chondrites. The facies and ichnofacies distinguished formed in pelagic or hemipelagic marine environments. Analysis of the correlation between δ13C and δ18O and of each of them with Sr and Fe/Ca and Sr/Ca, as well as the Z-factor, indicate that the geochemical signal has not been modified by diagenesis. In the PEL and PR sections, the δ13C and δ18O ratios do not allow to clearly identify isotopic events, except in CE where the Jenkyns Event was recorded. The proxies used to study detritism (Zr/Rb, Sr/Cu, Chemical Index Alteration, CIA, and C-value) show trends opposite to those detected in other Tethys sections and even between them. These peculiarities in the geochemical data are interpreted as the result of the opening of the Hispanic Corridor, the mixing of Panthalassa and Tethys seawaters and extensional tectonics, which favoured the development of half grabens with significant differential subsidence, especially during the NJT5b Subzone (latest Pliensbachian). These half grabens could be affected by contourite currents according to the Macaronichnus assemblage in some of these sections.
Evolution from carbonate platform to pelagic environments in the South Iberian Paleomargin (Pliensbachian-Early Toarcian, Early Jurassic): carbonate features and isotope geochemistry
(MDPI, 2023-10-29) Nieto, L.M.; Molina, J.M.; Ruiz-Ortiz, P.A.; Fraguas, A.; Reolid, M.
This paper studies ten Subbetic (Betic External Zones) stratigraphic sections spanning the Pliensbachian–early Toarcian time interval. Eight lithofacies were distinguished: crinoidal limestones, peloidal limestones, breccias, cherty limestones, nodular limestones, hardground surfaces and condensed levels, marls and marly limestone alternance, and dark marls. The biostratigraphy matches data from ammonite and calcareous nannofossil zonations. In addition, we analyzed C and O isotopes from bulk samples from three of the studied sections in which the lower Toarcian sedimentation crops out. The demise of the Lower Jurassic shallow platform developed in the South Iberian Paleomargin was a complex process driven by rifting, which led to tilted blocks giving way to different sedimentary environments. The tectonic stages occurred in the Sinemurian–Pliensbachian transition (R1), toward the lower part of the Ibex Zone (FO of the Biscutum grande, R2), in the Ibex– Davoei zones boundary (FO of Lotharingius barozii, R3), in the lower–upper Pliensbachian (R4), and in the lower boundary of the NJT4d nannofossil Subzone (R5) (Lavinianum Zone, upper Pliensbachian). After this last phase, sedimentation became pelagic in origin throughout the basin, represented by the sections studied. However, the isotope data show no clear record of the different C-isotopic events, though the Davoei–Margaritatus Event, the late Pliensbachian Event, and the Pliensbachian–Toarcian Boundary Event (PTBE) could be cautiously identified. These geochemical features are explained by the convergence of marine currents from Panthalassa (through the Hispanic Corridor) and Tethys.
Gold in the Alhambra: study of materials, technologies, and decay processes on decorative gilded plasterwork
(Wiley, 2014-02-24) de-la-Torre-López, María José; Domínguez-Vidal, Ana; Campos-Suñol, María José; Rubio-Domen, Ramón; Schade, Ulrich; Ayora-Cañada, María José
A complete study of the decayed gilded decorations of the stalactite vaults in the Hall of the Kings in the Alhambra complex (Granada, Spain) has been carried out for the first time. Preliminary investigations were carried out in situ using a portable Raman spectrometer and enabled the identification of tin (II) oxide in the black areas nearby the golden flakes. This suggested the presence of an altered tin foil. Then, a comprehensive characterization of these decorations was achieved through the use of complementary nondestructive techniques working on microsamples. Two main metallic structures were identified by means of scanning electron microscopy coupled to energy dispersive X-ray spectroscopy: (1) a thin (1–2 μm) gold leaf (probably original), and (2) redecorations with a laminated structure formed by a gold leaf placed over a thicker (10–15 μm) tin foil. Synchrotron Fourier transform infrared microspectroscopy revealed the use of proteinaceous glue to fix the gold leaf directly on the plasterwork, whereas in the case of the laminated structures, either glue or a natural resin was found. Raman microspectroscopy provided insight into the main decay processes affecting the gildings: the detachment of the metals due to the alteration of the organic materials employed as adhesives (forming calcium oxalates) and the oxidation of the tin foil. In addition, two technologies of false gilding have been encountered. One was based on a tin foil tinted to look like gold by means of a varnish (composed of a drying oil and a natural resin), and the second was made up with a tin–copper alloy (bronze) that appears severely degraded to copper oxalate and tin (II) oxide, as revealed by Raman microspectroscopy. Copyright © 2014 John Wiley & Sons, Ltd.
Holocene landscape evolution in the Baza Basin (SE-Spain) as indicated by fluvial dynamics of the Galera River.
(Elsevier, 2021) Wolf, D; García-Tortosa, FJ; Richter, C; Dabkowski, J; Roettig, CB; Faust, D
The concrete relationships between fluvial system behavior and potential influencing factors that are, among others, climate forcing, tectonics, and human activity are a key issue in geomorphological research. In this regard, especially the Iberian Peninsula is an area of great interest because its landscapes are highly sensitive towards climate changes and anthropogenic impact. Nowadays, the Iberian Peninsula reveals a strongly heterogeneous and spatially fragmented climate configuration. This should give rise to disparate behavior of fluvial geomorphic systems considering that climate is generally assumed the most important trigger of fluvial dynamics. In fact, river systems located in more humid and more arid regions in Iberia often reveal deviating patterns of Holocene floodplain evolution. This raises the question of whether these patterns were actually caused by a different climate history or if, alternatively, other factors might have been responsible. In this study, we investigated the Holocene floodplain evolution of the Galera River that is located in the upland of Eastern Andalucía (SE-Spain) named Baza Basin. A combination of detailed stratigraphic profile logging and closemeshed radiocarbon dating revealed that Holocene river dynamics generally followed the regional climatic development, which proves the Galera floodplain record to be a valuable archive of Holocene landscape evolution. However, we demonstrate that fluvial dynamics of the Galera system are hardly comparable to other river systems in Iberia even if the climate evolution was not so different. Our results suggest that in river systems with different basic conditions and catchment-specific configurations, similar climatic influences may lead to deviating fluvial process regimes (divergence phenomenon) because of substantial imprints of other parameters such as geological substratum, relief composition, tectonics, or human interventions.
In situ Raman spectroscopic study of marble capitals in the Alhambra monumental ensemble
(Springer, 2016-11-11) Arjonilla, Paz; Domínguez-Vidal, Ana; de-la-Torre-López, María José; Rubio-Domene, Ramón; Ayora-Cañada, María José
The marble capitals of five different sites in the Alhambra complex (Granada, Spain), namely the Mexuar, the Hall of the Abencerrages, the Hall of the Kings, the Court of the Myrtles and the Court of the Main Canal, have been investigated. The decoration of the capitals exhibits mainly blue, red, black and gilding motifs with different states of conservation. The work has been carried out in situ by means of a portable Raman micro-spectrometer with an excitation laser of 785 nm. In addition to preserving the artwork with a non-invasive study, the on-site investigation gives a more representative knowledge of the art objects because the measurements are not limited to the samples that can be taken (few and small). The obtained Raman spectra were of good quality despite challenging adverse conditions out of the laboratory. Cinnabar, minium, carbon black, natural lapis lazuli and azurite were the main pigments found. Synthetic ultramarine blue was also detected in a capital as a result of a modern restoration. Degradation products as tin oxide in the gildings and weddellite in the preparation layers were also identified. All the results together with a careful visual inspection can be combined to elucidate the different execution techniques employed to apply the pigments on the marble substrate of the capitals in the Nasrid and Christian periods.
Integrated cyclostratigraphy of the Cau core (SE Spain) - A timescale for climate change during the early Aptian Anoxic Event (OAE 1a) and the late Aptian
(Elsevier, 2024-01-16) Martínez-Rodríguez, Rafael; Batenburg, Sietske J.; Castro-Jiménez, José Manuel; de-Gea, Ginés; Nieto-Albert, Luis Miguel; Ruiz-Ortiz, Pedro Alejandro; Robinson, Stuart
We report a cyclostratigraphic study performed on the Cau core (Spain), which is considered an Aptian stratigraphic reference for global correlation and paleoenvironmental reconstruction. This investigation presents an astronomical timescale for the Aptian from the Ap2a to Ap14 carbon-isotope stages. Based on the evaluation of a multiproxy dataset from the Cau core, we recalibrate the age and duration of different biozones, bioevents, chemostratigraphic substages and horizons from the early and late Aptian, with special focus on the Selli Event, providing a new astronomical framework for Aptian climate. From the recognition of 14 long-eccentricity cycles, we propose a time span of 5.67 Ma from C-isotope segments Ap2a to the top of Ap14, and ages of 120.82 Ma for the onset of the nannoconid crisis, and 120.20 Ma for the onset of oceanic anoxic event (OAE) 1a. Calculations yield a duration of 1.47 Ma for OAE 1a. We estimate the age for the onset of the main non-radiogenic phase of the Os isotopes at 120.08 Ma, 120 ka after the onset of OAE 1a. The high-resolution data from the Cau core provide further insights in the temporal constraints of the OAE 1a and other Aptian paleoclimatic events. The onset of the main non-radiogenic excursion in Os isotopes occurring 120 ka after the onset of OAE 1a reinforces the theory of rapid destabilization of methane hydrates as the trigger of the anoxic event, that preceded the onset of large-scale volcanism.
Lanthanides in granulometric fractions of Mediterranean soils. Can they be used as fingerprints of provenance?
(Wiley, 2019-03-01) Martín-García, Juan M.; Molinero-García, Alberto; Calero, Julio; Fernández-González, María V.; Párraga, Jesús; Delgado, Rafael
There is geochemical interest in the lanthanides because they behave like a group that is closely related to the parent materials during surface processes, although they also undergo fractionation as a result of supergene dynamics. We analysed lanthanide concentrations (ICPms) in the granulometric fractions fine sand, clay and free forms of clay (FFclay-CDB and FFclay-Ox: extracted with citrate-dithionite-sodium bicarbonate and with ammonium oxalate, respectively) from a soil chronosequence of Mediterranean soils. There was a relative enrichment of heavy rare earth elements (HREE) in the clay fraction and its free forms with respect to fine sand. The clay free forms behaved as scavengers of lanthanides, and oxidative scavenging of cerium (Ce) in FFclay-CDB was also detected. Lanthanide concentrations (lanthanum to gadolinium in fine sand; terbium to lutetium in clay) varied with soil age, and chronofunctions were established. There was a strong positive collinearity between most of the lanthanide concentrations. Furthermore, the value of the correlation index (Pearson's r) of the concentrations between couples of lanthanides (r(CLC)) decreased significantly with increasing separation between the elements in the periodic table; this has never been described in soils. Several geochemical properties and indices in the fine sand and clay soil fractions and in the geological materials of the Guadalquivir catchment showed, on the one hand, a genetic relation between them all, enabling the lanthanides to be used as fingerprints of provenance; on the other hand, fractionation between fine sand and clay showed these are actively involved in soil lanthanide dynamics.
Mobility and Bioavailability of Metal(loid)s in a Fluvial System Affected by the Mining and Industrial Processing of Pb
(MDPI, 2021-04-06) Cortada, Unai; Hidalgo, María Carmen; Martínez, Julián; de la Torre, María José
Nitrogen recycling across a spectrum of fertilization strategies: an assessment in olive groves
(Elsevier, 2024-09-15) Domouso, Pablo; Calero, Julio; Ruiz-Cátedra, Gustavo; García-Ruiz, Roberto
Under the Zero pollution action, there is a strong emphasis on promoting management practices that enhance nitrogen (N) cycling to decrease reliance on inorganic N fertilizers and mitigate potential environmental impacts. Olive (Olea europaea L.) groves constitute the dominant landscape of many areas of Southern Mediterranean as Andalusia (Spain). Different farming models coexist in the olive sector, but they had not been studied in the context of N cycle. By integrating field and model data, we analyzed N flows, N balance, levels of N cycling closure, and N footprints in olive groves employing various cultivation models. Farms were categorized on: Org (organic external fertilization, high level of biomass recycling, temporary spontaneous cover crops), Tra (organic external fertilization, low recycling, bare soil), Int (inorganic external fertilization, low recycling, bare soil) and IPr (inorganic or organic external fertilization, low recycling, temporary spontaneous cover crops). Tree N demand, averaging 55 kg ha-1 y-1, correlated with fruit production and canopy area, making them suitable proxies for calculating N demand without exhaustive sampling. The N balance was positive for all farming models, with the Org model showing a more neutral balance (+7.4 kg N ha-1 y-1) and the IPr olive farms showing surpluses (+40.2 kg ha-1 y-1). In Org farms, annual N inputs were the lowest and rely on natural entries like N fixation, while Cycling Index was significantly higher than those of other groups (between 1.45 and 1.81 times). This was attributed to N recirculation mechanisms such as cover crops, shredding tree pruning, and returning harvested N through composted olive mill pomace. Soil erosion, often overlooked, emerged as a major N outflow, especially in Org farms with the highest soil N content, resulting in the highest N losses per liter of oil. Per liter of olive oil, Trad, Ipr, and Int farms use between 1.9 and 2.2 times more anthropogenic N inputs than Org farms. Overall, our results highlight significant potential to enhance internal N cycling, increase self-sufficiency, and extend the lifespan of N in olive farming by implementing scalable management practices that promote nature-based processes.
Progradation of a shallow carbonate platform developed on a fault-block in the Western Tethys (lower Aptian, Sierra de Bedmar-Jódar, Prebetic of Jaén, Spain)
(Springer, 2023-04-10) Martínez-Rodríguez, R.; Nieto, L.M.; Castro, J.M.; de Gea, G.A.; Ruiz-Ortiz, P.A.; Molina, J.M.; Skelton, P.W.
The Middle Member of the Llopis Fm in the Sierra de Bedmar-Jódar Unit of the Prebetic Zone of Jaén (southern Spain) was deposited on a shallow-marine platform of the Southern Iberian Continental Margin during the earliest Aptian. Detailed field logging of nine stratigraphic sections and facies mapping have allowed seven lithofacies associations (L1–L6) to be distinguished, one siliciclastic (L1) and five carbonate facies (L2–6). The succession is composed of eight consecutive elemental sequences of lithofacies associations L1–L6. Each elemental sequence is interpreted as representing one episode of shallowing-upwards carbonate deposition in a very shallow platform-lagoon that was bounded shoreward by clastic/ooid bars and passed seaward either to stromatoporoid bioconstructions (bioherms and biostromes) or rudist biostromes. The successive elemental sequences show north-eastward progradational geometries. Three phases of platform development are identified: (1) installation of the shallow platform; (2) development of a lagoon bounded by a stromatoporoid barrier and (3) development of an Urgonian-type platform dominated by rudists. During the early Aptian, the Bedmar-Jódar platform was partially isolated from the rest of the Prebetic platform and showed overall progradation towards the NE, in contrast to the general south-eastward progradational trend of the Prebetic platform. Sedimentation was controlled by rift-generated extensional tectonics that resulted in tilting of the platform block, causing the deviation of progradation from the general trends of the Prebetic Platform. In addition, climatic influence is inferred from the presence of siliciclastic sediments derived from weathering of the hinterland, which restricted the carbonate factory.

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