DG-Artículos

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.
A lower Valanginian coral fauna from the South Iberian Palaeomargin (Internal Prebetic, SE Spain)
(Paleontological Society, 2021-02) Lösser, H.; Nieto, L.M.; Castro, J.M.; Reolid, M.
From the Lower Valanginian of the Sierra de Cazorla (Internal Prebetic, SE Spain), a coral fauna is taxonomically described. The fauna encompasses 51 species in 29 genera. One genus and three species are described as new. The most speciesrich are the superfamilies Cyclolitoidea and Stylinoidea. The faunal composition is ambivalent and encompasses typical Jurassic taxa, such as members of the families Amphiastraeidae, Rhipidogyridae, Solenocoenidae and Stylinidae, but also typical Cretaceous elements such as the genera Confusaforma, Floriastrea and Holocoenia (which also have their first occurrence in the Valanginian studied fauna). Four Jurassic genera show a range extension into the Early Valanginian: Alloiteaucoenia, Bilaterocoenia, Hykeliphyllum and Miscellosmilia. Other genera still survived into the Late Valanginian (Placogyra, Rhipidogyra and Solenocoenia) but became extinct. A palaeobiogeographic analysis shows relationships of the studied fauna to the Tithonian and the Kimmeridgian of the northern Tethys on one hand, and the Hauterivian of the Paris Basin and the Puebla Basin (Mexico) on the other. Nineteen species of the studied fauna remained in open nomenclature; the majority of them probably represent new species.
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.
Active faulting in the central Betic Cordillera (Spain): Palaeoseismological constraint of the surface-rupturing history of the Baza Fault (Central Betic Cordillera, Iberian Peninsula).
(Elsevier, 2018) Castro-Sabio, Julia; Martín-Rojas, Iván; Medina-Cascales, Iván; García-Tortosa, Francisco Juan; Alfaro, Pedro; Insua-Arévalo, Juan Miguel
This paper on the Baza Fault provides the first palaeoseismic data from trenches in the central sector of the Betic Cordillera (S Spain), one of the most tectonically active areas of the Iberian Peninsula. With the palaeoseismological data we constructed time-stratigraphic OxCal models that yield probability density functions (PDFs) of individual palaeoseismic event timing. We analysed PDF overlap to quantitatively correlate the walls and site events into a single earthquake chronology. We assembled a surface-rupturing history of the Baza Fault for the last ca. 45,000 years. We postulated six alternative surface rupturing histories including 8–9 fault-wide earthquakes. We calculated fault-wide earthquake recurrence intervals using Monte Carlo. This analysis yielded a 4750–5150 yr recurrence interval. Finally, compared our results with the results from empirical relationships. Our results will provide a basis for future analyses of more of other active normal faults in this region. Moreover, our results will be essential for improving earthquake-probability assessments in Spain, where palaeoseismic data are scarce.
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.
Assessment of geodiversity in the southern part of the Central Iberian Zone (Jaén Province): usefulness for delimiting and managing natural protected areas
(Springer, 2020-02-03) Fernández, A.; Fernández, T.; Pereira, D.I.; Nieto, L.M.
To explore the relationship between geodiversity and borders of natural protected areas, we studied the northern part of Jaén Province (southern Spain), where the southern sector of the Central Iberian Massif, the Betic Cordillera and the Guadalquivir foreland basin come together. Moreover, several natural protected areas (NPAs) are located here. To approach the topic, we defined the geodiversity index as the sum of partial indices: lithological, geomorphological, palaeontological, pedological, minerals, hydrology and geosites. This made it possible to derive a map of the geodiversity index and a map of geodiversity gradient. Analysis of their distribution shows that almost 80% of the territory has values of medium, high and very high geodiversity, but these zones are situated outside the borders of the NPAs. A similar study considering two biological indices (endangered species and biodiversity) shows a good correlation between the limits of NPAs and the higher values of these indices. Thus, an absence of correlation between the geodiversity index and biological indices is clearly detected. These results are not in agreement with the definition of NPAs in the current Spanish laws of nature conservation.
Assessment of tailings ponds by means of a combination of electrical (ERT and IP) and hydrochemical techniques (Linares, southern Spain).
(Springer, 2021) Rey, Javier; Martínez, Julián; Hidalgo, M. Carmen; Mendoza, Rosendo; Sandoval, Senen
Accumulated mine waste in certain locations in the abandoned mining district of Linares-La Carolina (southern Spain) contain high levels of metals. Therefore, in recent years, many of these tailings ponds have been restored and sealed. This study assessed the efficacy of two geophysical techniques, electrical resistivity tomography (ERT) and induced polarisation (IP), combined with hydrochemical studies, as tools to image the effectiveness of the encapsulation. In the bedrock, ERT profiles distinguished a surficial layer of moderate-low resistivity values (below 80 Ω m), associated with alluvial sands or altered granite, and a deeper zone of high resistivity (up to 1000 Ω m) related to unaltered granite basement. Lateral changes in resistivity were identified inside the upper layer and downstream of the tailings pond. The IP profiles detected local anomalies in the chargeability values (up to 8 mV/V), unusual in granitic rocks. The locations with high chargeability also had low resistivity, which typically indicates the percolation of mining leachates in the underlying altered granites. Integration of geological and geochemical information confirmed this interpretation. This work verified that the combined use of ERT and IP methods were effective for monitoring ancient tailings ponds and for assessing tailings encapsulation.
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 Gómez, Elena; de la Torre-López, María José; Ayora-Cañada, María José
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.
Correlation of banana productivity levels and soil morphological properties using regularized optimal scaling regression
(Elsevier, 2022-06) Olivares, Barlin O.; Calero, Julio; Rey, Juan C.; Lobo, Deyanira; Landa, Blanca B.
Soil morphological properties described in the field, such as texture, consistence or structure, provide a valuable tool for the evaluation of soil productivity potential. In this study, we developed a regression model between the soil morphological variables of banana plantations and a crop Productivity Index (PI) previously developed for the same areas in Venezuela. For this, we implemented categorical regression, an optimal scaling procedure in which the morphological variables are transformed into a numerical scale, and can thus be entered in a multiple regression analysis. The model was developed from data from six plantations growing “Gran Nain” bananas, each with two productivity levels (high and low), in two 4-ha experimental plots, one for each productivity level. Sixty-three A horizons in thirty-six soils were described using 15 field morphological variables on a nominal scale for structure type, texture and hue, and an ordinal scale for the rest (structure grade, structure size, wet and dry consistence, stickiness, plasticity, moist value, chroma, root abundance, root size, biological activity and reaction to HCl). The optimum model selected included biological activity, texture, dry consistence, reaction to HCl and structure type variables. These variables explained the PI with an R2 of 0.599, an expected prediction error (EPE) of 0.645 and a standard error (SE) of 0.135 using bootstrapping, and EPE of 0.662 with a SE of 0.236 using 10- fold cross validation. Our study showed how soil quality is clearly related to productivity on commercial banana plantations, and developed a way to correlate soil quality indicators to yield by using indicators based on easily measured soil morphological parameters. The methodology used in this study might be further expanded to other banana-producing areas to help identify the soils most suitable for its cultivation, thereby enhancing its environmental sustainability and profitability.
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
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, L.M.; Ayadi, C.; Fraguas, A.; Molina, J.M.; Reolid, M.
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
High-resolution C-Isotope, TOC and biostratigraphic records of OAE1a (Aptian) from an expanded hemipelagi cored succession, Western Tethys: a new stratigraphic reference for global correlation and paleoenvironmental reconstruction
(Wiley, 2021-02-08) Castro-Jiménez, José Manuel; Ruiz-Ortiz, Pedro A.; de Gea, Ginés A.; Aguado-Merlo, Roque; Jarvis, Ian; Weissert, Helmut; Molina-López, José Manuel; Nieto-Albert, Luis Miguel; Pancost, Richard D.; Quijano, Maria Luisa; Reolid, Matías; Skelton, Peter William; López-Rodríguez, Carmina; Martínez-Rodríguez, Rafael
A high-resolution carbonate C-isotope stratigraphy for the Aptian is presented for the Cau core (Spain). The biostratigraphically calibrated C-isotope stratigraphy of the core is used to refine the previously defined C-isotope segments of the Aptian. Thirteen C-isotope segments have been identified and correlated, and further subdivisions are presented. Correlation with other sections worldwide demonstrates the robustness of the C-isotope stratigraphy of the Cau core. The studied succession includes a continuous record of the early Aptian Oceanic Anoxic Event (OAE 1a). Its onset has been studied at an ultrahigh-resolution scale (0.2–0.5 kyr spacing), revealing a succession of sharp δ13Ccarb negative spikes, interpreted as a record of pulses of volcanism and methane emissions. The largest spike was rapid (<10 kyr) and marks the base of OAE 1a, which occurs within a longer-term falling δ13Ccarb trend. The C-isotope profile across OAE 1a perfectly records the negative (C3/Ap3), positive (C4/Ap4), steady (C5/Ap5), and positive (C6/Ap6) segments that were defined from Cismon (Italy) and subsequently identified worldwide. The Ap7 to Ap14 segments record a C-isotope negative excursion, coupled with high TOC contents, probably related to regional paleogeography. The links with global environmental changes, episodes of widespread deposition of organic matter, and ultimately to major volcanic episodes are discussed. We propose the Cau core as a new reference section for the Aptian, and specifically for OAE 1a, based on its expanded and well-preserved sedimentary, geochemical and biotic archives, which provide further insights into the environmental and biotic changes that occurred during this time interval.
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.

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