Granada Basin Research Articles

Reprocessing and interpretation of legacy seismic data using machine learning from the Granada Basin, Spain

The Granada Basin (Spain) is a Neogene sedimentary depression with irregular geomorphology and deep depocenters. It is located in the most seismically hazardous part of the Iberian Peninsula with an historically experienced extremely destructive earthquakes, followed by periods of low to moderate seismicity. In 1980s the Chevron Oil Company collected a set of 30 deep seismic reflection sections in this Basin of which only the results on paper are kept. Due to the fact that many of these seismic profiles are currently located in urban areas and the economic cost of carrying out a similar exploration, it was decided to recover these old data and apply a post-stack treatment to improve their quality. The purpose of this study is to show the applied reprocessing flow and, with the new sections, to present a spatial model of the basin. The first stage of recovery and enhacement of seismic sections has consisted in three phases: first, high-resolution scanning of paper copies to TIFF images followed by the transformation of TIFF images to SEG-Y format; second, poststack processing workflow to increasing resolution and lateral coherence of these seismic lines; and third, it has been used a machine learning algorithm, among others, increasing the spatial resolution, signal-to-noise ratio, and coherence of the seismic signals. In addition, basement horizons, as well as three sedimentary sequences, were identified in all seismic sections and interpolated to create a three-dimensional basement model composed by normal faults, horst and grabens related to the seismotectonic behavior of the basin. As an overall assessment, this work is an example of the usefulness of ‘recycling’ legacy seismic data, which nowadays are usually in archived boxes, but at the time required a great economic and acquisition effort.

Seismogenic structures and active creep in the Granada Basin (S-Spain)

The Granada Basin is a slowly deforming intramountain basin in the Betic Cordillera (S-Spain). Despite historical and paleoseismological evidence for M6 earthquakes, instrumental seismicity lacks large events and the seismotectonic model must be built from small earthquakes (M < 5). Here, we reanalyze 35 years of data from the Granada Basin short period network, and further seismic stations with shorter operating time, to identify seismogenic structures and understand their relationships. We sort events with similar waveforms into multiplet clusters and perform relative location to image active fault patches. Cluster orientations are used as a priori constraint for inverting focal mechanisms from composite cluster polarity measurements. We further estimate moment tensor solutions from full waveform inversion using local and regional broadband stations. We can identify four groups of structures at different positions in the basin: 1) in the northeast sector, we observe shallow, NW-SE striking, high-angle normal faulting, often related with known fault structures; 2) the southern sector shows high-angle normal faulting on unmapped, ∼E-W striking structures at mid-crustal depths; 3) between both groups, we image sub-horizontal fault patches, associated with the basal detachment beneath the basin, showing SSW transport direction; 4) at the western limit of the basin, we find ∼N-S trending, left-lateral strike-slip faults. Groups 2 and 3 are characterized by clusters with overall constant event production rate, indicating ongoing and largely aseismic creep of the basal detachment over the last 35 years. Seismological evidence suggests a locking depth of ∼10 km and a brittle-ductile transition near 15 km, according to the depth range of clusters in groups 2 and 3.

Active Shortening Simultaneous to Normal Faulting Based on GNSS, Geophysical, and Geological Data: The Seismogenic Ventas de Zafarraya Fault (Betic Cordillera, Southern Spain)

AbstractThe central Betic Cordillera, southern Spain, is affected by an uplift related to the NNW–SSE Eurasia‐Nubia convergence and shallow ENE–WSW orthogonal extension accommodated by the extensional system of the Granada Basin. The combination of geophysical, geodetic, and geological data reveals that the southwestern boundary of this extensional system is a seismically active compressional front extending from the W to the SW of the Granada Basin. The near‐field Global Navigation Satellite System data determine NNE–SSW shortening of up to 2 mm/yr of the compressional front in the Zafarraya Polje. In this setting, the normal Ventas de Zafarraya Fault developed as a result of the bending‐moment extension of the Sierra de Alhama antiform and was last reactivated during the 1884 Andalusian earthquake (Mw 6.5). The uplift in the central Betic Cordillera together with the subsidence in the Western Alborán Basin may facilitate a westward to southwestward gravitational collapse through the extensional detachment of the Granada Basin. The heterogeneous crust of the Betic Cordillera would generate the compressional front, which is divided into two sectors: thrusting to the west, and folding associated with buttressing to the south. Our results evidence that basal detachments, linking extensional fault activity with compressional fronts, may determine the activity of local surface structures and the geological hazard in densely populated regions.

Evaluation of road network slopes susceptibility to seismically-induced landslides in the Granada Basin (S Spain)

In this work, a method for the fast evaluation of seismically-induced landslides is applied at regional scale in the Granada Basin (southern Spain). The methodology is based on the concept of rigid block but takes into account the variability in input data (geotechnical properties, failure depth and saturation state of the materials) through the use of a logical tree scheme. Input data were combined and evaluated using five different Newmark displacement empirical relations, which are automatically weighted to obtain a final co-seismic landslide susceptibility map. A Geographic Information System system was used to obtain the resulting maps considering the different branches and weights of the logic tree through an specifically developed automatic code written in Phyton. The landslides induced by the 2021 Mw 4.4 events of the Santa Fe seismic series have been used to validate the methodology. This is later used as input along with the road network to analyze the distribution of areas of different susceptibility level. The results obtained show that 1.73% of the total area is characterized by moderate to high susceptibility, being the southern and eastern sections of the Granada basin were more vulnerable slopes are found. When considering only zones around the road network (50 m buffer), it is found that 2.11% of slopes around highways and 1.33% of road slopes have moderate to high susceptibility, especially the A-92 highway and the A-338 road. These roads traverse areas with steep slopes and a combination of hard and soft materials, which increases the susceptibility of disrupted landslides. On the other hand, in more densely populated areas such as the metropolitan area of Granada, the susceptibility is lower due to their location on terrain with low to negligible slopes. The results are of interest for authorities managing slope stabilities because they allow establishing effective and locally-based seismic forecast works in order to minimize the damage of future events.

Active Collapse in the Central Betic Cordillera: Development of the Extensional System of the Granada Basin

The Betic Cordillera was formed by the collision between the Alboran Domain and the South Iberian paleomargin in the frame of the NW–SE convergent Eurasia–Nubia plate boundary. The central region is undergoing a heterogeneous extension that has not been adequately analysed. This comprehensive study addressed it by collecting structural geologic, seismologic, and geodetic data. The region west of the Sierra Nevada is deformed by the extensional system of the Granada Basin, which facilitates E–W to NE–SW extension. Moreover, the southern boundary of Sierra Nevada is affected by a remarkable N–S extension related to E–W normal to normal–dextral faults affecting the shallow crust. However, geologic and geodetic data suggest that the western and southwestern Granada Basin boundary constitutes a compressional front. These data lead to the proposal of an active extensional collapse from the uplifted Sierra Nevada region to the W–SW–S, over an extensional detachment. The collapse is determined by the uplift of the central Betics and the subsidence in the Alboran Basin due to an active subduction with rollback. Our results indicate that the central Betic Cordillera is a good example of ongoing extensional collapse in the general context of plate convergence, where crustal thickening and thinning simultaneously occur.

Near-surface characterization using distributed acoustic sensing in an urban area: Granada, Spain

SUMMARY The Granada Basin in southeast Spain is an area of moderate seismicity. Yet, it hosts some of the highest seismic hazards in the Iberian Peninsula due to the presence of shallow soft sediments amplifying local ground motion. In urban areas, seismic measurements often suffer from sparse instrumentation. An enticing alternative to conventional seismometers is the distributed acoustic sensing (DAS) technology that can convert fibre-optic telecommunication cables into dense arrays of seismic sensors. In this study, we perform a shallow structure analysis using the ambient seismic field interferometry method. We conduct a DAS array field test in the city of Granada on the 26 and 27 August 2020, using a telecommunication fibre. In addition to the existing limitations of using DAS with unknown fibre-ground coupling conditions, the complex geometry of the fibre and limited data recording duration further challenge the extraction of surface-wave information from the ambient seismic field in such an urban environment. Therefore, we develop a processing scheme that incorporates a frequency–wavenumber (f−k) filter to enhance the quality of the virtual shot gathers and related multimode dispersion images. We are able to use this data set to generate several shear-wave velocity (VS) profiles for different sections of the cable. The shallow VS structure shows a good agreement with different geological conditions of soil deposits. This study demonstrates that DAS could provide insights into soil characterization and seismic microzonation in urban areas. In addition, the results contribute to a better understanding of local site response to ground motion.

Insights of Active Extension Within a Collisional Orogen From GNSS (Central Betic Cordillera, S Spain)

AbstractThe coexistence of shortening and extensional tectonic regimes is a common feature in orogenic belts. The westernmost end of the Western Mediterranean is an area undergoing shortening related to the 5 mm/yr NNW‒SSE convergence of the Nubia and Eurasia Plates. In this region, the Central Betic Cordillera shows a regional ENE‒WSW extension. Here, we present GNSS‐derived geodetic data along a 170 km‐long transect orthogonal to the main active normal faults of the Central Betic Cordillera. Our data indicate that the total extension rate along the Central Betic Cordillera is 2.0 ± 0.3 mm/yr. Extension is accommodated in the eastern (0.8 ± 0.3 mm/yr in the Guadix‐Baza Basin) and western (1.3 ± 0.3 mm/yr in the Granada Basin) parts of the Central Betic Cordillera, while no extension is recorded in the central part of the study area. Moreover, our data permit us to quantify, for the first time, short‐term fault slip rates of the Granada Fault System, which is one of the main seismogenic sources of the Iberian Peninsula. We deduce a fault slip rate of ∼1.3 ± 0.3 mm/yr for the whole Granada Basin, with 0.9 ± 0.3 mm/yr being accommodated in the Granada Fault System and 0.4 ± 0.3 mm/yr being accommodated in the southwestern sector of the Granada Basin, where no active faults have been previously described at the surface. The heterogeneous extension in the Central Betic Cordillera could be accommodated by shallow high‐angle normal faults that merge with a detachment at depth. Part of the active extension could be derived from gravitational instability because of underlying over‐thickened crust.

Chemical and Mineralogical Characterization of Montevive Celestine Mineral

The Montevive celestine mineral deposit, set in the Granada Basin in a marine evaporitic uppermost Tortonian–lowermost Messinian sequence, is the largest reserve in Europe of this economically important strontium ore. Currently, the mine has a large amount of tailings resulting from the rejection of a manual dry screening of high-grade celestine mineral. This visual and density screening was carried out in the early days of mining (1954–1973). Concentrating the celestine mineral and increasing the ore recovery rate would reduce mine operation costs and the generation of new tailings, reducing the impact on the environment. In order to define more adequate concentration methods, we have used complementary analytical techniques such as optical (OM) and scanning and transmission electron microscopy (SEM and TEM), energy-dispersive X-rays (EDXs), X-ray fluorescence (XRF), and X-ray diffraction (XRD) to fully characterize the morphology, microstructure, chemistry, and mineralogy of the celestine mineral. The low-grade mineral is made of prismatic celestine crystals that are replacing a matrix of micro sparry calcite. Other minority minerals are strontianite, dolomite, quartz, and clays (kaolinite, paragonite, and illite). There is also a certain amount of iron oxides and hydroxides (mainly magnetite) associated with clays. We showed that the concentration of low-grade celestine mineral can be achieved through a low-cost and eco-friendly method based on grinding and size separation. The coarser fractions (&gt;5 mm) have more celestine (up to 12 percent units higher than the starting unprocessed mineral) due to the selective loss of calcite and minority minerals (quartz, clays, and iron oxides) that are mainly found in the finer fraction (&lt;1 mm). This process can make mine exploitation more sustainable, reducing the generation of residues that negatively impact the environment.

The Role of Faults as Barriers in Confined Seismic Sequences: 2021 Seismicity in the Granada Basin (Betic Cordillera)

AbstractFault barriers are key structures for studying seismic hazard in regions of intense brittle deformation. The interaction between fault sets affects their seismogenic behavior, if some of them act as barriers. The Granada Basin, in the Betic Cordillera, is a region affected by shallow brittle deformation, as it was the scenario for the recent Granada 2021 seismic sequence. This seismicity presented a swarm behavior at the beginning of the sequence, followed by mainshock‐aftershock features. Geological and gravity data presented here reveal that the basement is affected by two sets of NW‐SE and NE‐SW normal faults and intensely deformed by vertical NW‐SE joints. Improved relocation of the Granada 2021 seismicity reveals a confined chimney‐shape seismicity caused by the activity of a 2 km long NW‐SE normal fault segment. The confinement of the sequence is associated with the NE‐SW fault set acting as a barrier that restricts the rupture area, limiting the maximum magnitude, and favoring the recurrence of events with smaller magnitude. The chimney‐shape of the seismic sequence suggests that the deformation is propagated vertically to the surface, facilitated by preexisting fractures. The shallow extensional deformation during the uplift of the central Betic Cordillera drove the activity of the local structures obliquely to the regional extensional trends, as evidenced by the seismic sequence. This multidisciplinary study improves the knowledge on the origin of the Granada Basin and underlies the important role of preexisting fractures on fault segmentation and seismic propagation, decreasing the seismic potential of this area.

Semi-multilamellar growth in Reptomulticavata alhamensis, a new cyclostome (Bryozoa) species from the Tortonian of Alhama de Granada (S. Spain).

In the Tortonian beds of Alhama de Granada within the Granada Basin severa! large, oblate to spheroid, bryozoan colonies are found belonging to a new species of Cyclostomata. Reptomulticava alhamensis nov. sp. presents a semimultilamellar growth in contrast with the prevailing clear multilamellar growth in other Reptomulticava and related genera. Like R. multigemmata , this species buds axially.

Seismic Analysis of the 2020–2021 Santa Fe Seismic Sequence in the Granada Basin, Spain: Relocations and Focal Mechanisms

Abstract The 2020–2021 Santa Fe seismic sequence is the first well-instrumented and widely felt seismic series occurred in the Granada basin during the Spanish instrumental period since the 1979 Fuente Vaqueros seismic series and the 1955–1956 Armilla and Purchil destructive earthquakes. It began in December 2020 with an Mw 3.7 earthquake followed by five Mw&amp;gt;4 earthquakes between 23 and 28 January 2021 and a long sequence of aftershocks during the next four months. Over six months later, on 12 August, another large earthquake of magnitude 4.5 stroke the area to the southwest of Santa Fe city where the previous shocks occurred. This seismic sequence offers a unique opportunity to study the seismic activity in this region—one of the most seismically active zones and with the highest seismic hazard in the Iberian Peninsula. The wide station coverage and good-quality data available allows us to perform high-precision absolute and relative relocations and to obtain the seismic moment tensor (MT) and focal mechanism of the largest earthquakes. Relocation results reveal a clustered distribution of the seismicity between Santa Fe and Pinos Puente faults, focused on a depth range between 2 and 5 km. Hypocenters follow a near-vertical pattern, and Mw&amp;gt;4 events display a northeast–southwest-dipping trend that seems to fit Pinos Puente fault plane. However, regional MT solutions show predominant normal fault mechanisms, with minor oblique component but with strike and dip orientations more compatible to Santa Fe fault. To explain this apparent discrepancy with the known mapped active faults, we propose a change in dip of Santa Fe fault plane from near vertical at shallow depths, bended below the first kilometers, to a possible fault splay in depth compatible with the known geologic structure of the area.

High‐ and Low‐Angle Normal Fault Activity in a Collisional Orogen: The Northeastern Granada Basin (Betic Cordillera)

AbstractUnderstanding active tectonics and seismicity in extensional settings requires the analysis of high‐angle normal faults (HANFs) and the transfer of deformation at depth. The debate surrounds the role of low‐angle normal faults (LANFs) in triggering high magnitude earthquakes. The central Betic Cordillera is an active seismic zone affected by the NNW‐SSE Eurasia‐Nubia convergence and orthogonal extension. The seismicity and present‐day stress determined by earthquake focal mechanisms reveals the activity of a NE‐SW extensional system in the shallowest 12 km of the Granada Basin. The structure of the sedimentary infill, as derived by geological field and gravimetric techniques, suggests the formation of a half‐graben tilted to the N‐NE. Seismologic data suggest the activity of HANFs above 6–7 km depth and a LANF zone around 6–12 km depth, with related earthquakes of up to Mw 4.0 and 20° to 30° fault dips. High‐precision leveling lines highlight the importance of the Granada Fault in the system, with average vertical displacement rates of 0.35–1.1 mm/yr. These data suggest creep fault behavior at the surface and increased seismicity at depth. The upper crustal extension in the collisional Betic Cordillera is accommodated by a top‐to‐the‐WSW extensional detachment related to westward motion and rollback in the Gibraltar Arc and the gravitational collapse of the cordillera, in a framework of NNW‐SSE shortening. This comprehensive study draws a new scenario that advances understanding of relationships between HANFs and LANFs.

Preliminary Insights of InSAR Applied to the Earthquake Swarm 2020-2021 in the Granada Basin by Using Open Resources

Preliminary Insights of InSAR Applied to the Earthquake Swarm 2020-2021 in the Granada Basin by Using Open Resources

Early Pliocene Desmaninae (Mammalia, Talpidae) from Southern Spain and the Origin of the Genus Desmana

ABSTRACT Desmaninae (water-moles) are common elements in the late Miocene–Pleistocene mammal assemblages from Europe, but knowledge about this group is still scarce. Here we present the desmanines from several early Pliocene localities of the Granada Basin, southern Spain. The species Desmana marci, sp. nov. is described from the sites Calicasas-3 and 4A, characterized, among other traits, by its slightly molarized p4, enormous P2, strongly molarized P3 and P4, and very large metaconule in the M3. Desmana marci shows a typical Desmana i1, with the enamel extending further down anteriorly than posteriorly, but an Archaeodesmana-like I1, low-crowned and bilobed. Desmana marci is proposed as the oldest species of Desmana; its origin lies in Archaeodesmana baetica, and it is in turn interpreted as the ancestor of Desmana verestchagini. Besides, a desmanine of small size and ascribed to Archaeodesmana cf. getica is identified in Calicasas-5A and Purcal-13. This desmanine forms part of a lineage leading to Archaeodesmana elvirae and Archaeodesmana brailloni; this lineage is characterized by an increase in size and in the molarization of the upper premolars. Desmaninae are identified in all the latest Miocene and earliest Pliocene localities from the Granada Basin, evidencing the existence of permanent water bodies. On the contrary, they are not found in sites of similar age in the Guadix Basin, which would have had more arid conditions. The coincident appearance of A. cf. getica in both basins during the early Ruscinian indicates a change towards more humid conditions in the region, allowing the establishment of permanent water flows in the Guadix Basin. http://zoobank.org/urn:lsid:zoobank.org:pub:E3E441D0-CF66-4320-AA2E-17FB7BC10B39

Intrusions of dust and iberulites in Granada basin (Southern Iberian Peninsula). Genesis and formation of atmospheric iberulites

Fourteen samples of deposited atmospheric dust collected during desert dust intrusions over Granada in the summer of 2010 are studied here. During these atmospheric dust events the PM10 ranged from 25 μg m−3 to 200 μg m−3, surpassing occasionally the standard limit (50 μg m−3) established by the European Union Directive as a risk for the human health. The mineralogical composition of the dust samples is very heterogeneous, showing that the origin of collected particles is from north-northwest of Africa and local/regional soils. The analyzed dust samples contain between 1 and 9% of iberulites, polymineral spherical particles with diameter between 34 and 111 μm. New compositional results obtained by mapping chemical elements and mineral compositions of iberulites with VPSEM-EDEX technology allowed as to go further than previous studies and provide new insight on the iberulites genesis. The SEM-microstructure analysis of the iberulites and the compositional results obtained by VPSEM-EDEX technique showed that clay and sulphur components are important in determining their spherical shapes. The analysis also shows that iberulites present a typical vortex at one of the poles and an external covering by nano-clays in laminar clusters, a form of rind and a core internal with sizes less than 10 μm. On the other hand, the micromorphological analysis evidences that the bacteria and its polymeric exudates participate in the iberulite genesis, acting as aggregation agents and contributing to its protection and compensating its fragility. The role of bacteria and its polymeric exudates in the iberulite genesis has not been described previously, and it would explain the flux, transport and survival of tropospheric microorganisms over long distances. These new observations and finding led us to take into account the role of bacteria in iberulite genesis and to reconsider the previous hypothesis regarding the iberulite genesis proposed in previous works.

Effect of Mineral Processes and Deformation on the Petrophysical Properties of Soft Rocks during Active Faulting

We have studied damage zones of two active faults, Baza and Padul faults in Guadix-Baza and Granada basins, respectively, in South Spain. Mineral and microstructural characterization by X-ray diffraction and field emission electron microscopy studies have been combined with structural fieldwork and in situ measurements of rock properties (permeability and Young’s modulus) to find out the relation between deformation behavior, mineral processes, and changes in the soft rock and sediment properties produced by fluid flow during seismic cycles. Our results show that microsealing produced by precipitation of dolomite and aragonite along fractures in the damage zone of Baza Fault reduces the permeability and increases the Young’s modulus. In addition, deformation bands formed in sediments richer in detrital silicates involved cataclasis as deformation mechanism, which hamper permeability of the sediments. In the Granada Basin, the calcarenitic rocks rich in calcite and clays in the damage zone of faults associated to the Padul Fault are characterized by the presence of stylolites without any carbonate cement. On the other hand, marly lithofacies affected by faults are characterized by the presence of disaggregation bands that involve cracking and granular flow, as well as clay smear. The presence of stylolites and deformation bands in these rocks reduces permeability.

Sedimentology and diagenetic evolution of the Neogene ‘Intermediate Sandstone Unit’ in the halite deposits of the Granada Basin (SE Spain): the turning point in the change from marine to continental sedimentation

The Granada Basin is a small (50 × 50 km) Neogene intramontane basin located in the central part of the Betic Cordillera (Spain). In the latest Tortonian, the Granada Basin desiccated and a thick salt succession formed, encompassing three halite-bearing units: the ‘Lower Halite Unit’, the ‘Intermediate Sandstone Unit’ (ISU), and the ‘Upper Halite Unit’ (UHU). ISU deposits record the onset of marine to non-marine conditions in the Granada Basin. The main purpose of this paper is to study the environment of formation and the diagenetic evolution of the ISU salt-bearing unit, in order to assess the events leading to and resulting from the continentalization of this basin in the late Miocene. This study includes visual core descriptions, petrographic (conventional petrography and scanning electron microscopy), and geochemical (δ34S and δ18O and 87Sr/86Sr) analyses. ISU deposition took place in a coastal lake, isolated from the open sea by a sand barrier. Lake evolution was from a very shallow, hypersaline lacustrine environment to a deeper, perennial lake undergoing frequent storm-induced marine flooding and, finally, to a shallower, perennial saline lake. Isotope analyses point to a mixture of different inflow waters, including marine- and underground (hydrothermal)-water inputs for the origin of the brines. Halite dissolution occurred after flooding events and clear-halite cement was precipitated inside primary-halite dissolution cavities. Early diagenesis involves halite re-crystallisation during repetitive, dissolution–precipitation cycles, gypsum replacement by halite, halite replacement by nodular anhydrite, and framboid pyrite formation. Intermediate- to late-diagenetic processes are silica (megaquartz, chalcedony, and lutecite) replacement of halite and anhydrite, and celestine replacement. Megaquartz formation relates to sulfate-depleted, UHU percolating brines. Chalcedony and lutecite crystallization took place sometime later from sulfate-rich percolating brines, during deposition of the gypsum sequence occurring on top of the salt. Celestine, replacing lutecite, resulted from the interaction with Sr-rich underground waters (via dissolution of previously formed celestine).

Late Miocene vertical movements in the Sierra Nevada and Granada Basin linking zone (Betic Cordillera, Spain): insights from marine microfossils

Purpose Marine microfossils, specifically planktonic and benthic foraminifera, are a valuable tool to constrain the age (biostratigraphy) and water depth (paleobathymetry) of the sedimentary record in the Granada Basin. Using both data sources, our study has aimed to illustrate the history of the vertical movements in the tectonically uplifted sectors of this basin that currently form part of the relief of the Sierra Nevada.

A lithostratigraphic and palaeoenvironmental framework for the late Miocene El Caracolar section (Granada Basin, Betic Cordillera, Spain) and description of decapod crustaceans

The locality of El Caracolar in the Granada Basin (Central Betic Cordillera, southern Spain) has yielded a rich late Miocene assemblages composed of marine invertebrates and vertebrates, accompanied by microfossils, macroflora and trace fossils. Exposed strata consisting of sands, sandy siltstones, silty sandstones, siltstones and calcirudites are divided into four local units. Lithostratigraphically, the studied section is placed between the top of the La Peza Formation and the Quéntar Formation. Based on foraminifers, the age of units 2 and 3 is estimated to be early Tortonian (11.0–9.9 Ma), whereas units 1 and 4 do not yield any reliable biostratigraphic markers. The diverse biotic association suggests that deposition took place in a near-shore outer neritic zone of a narrow to open seaway in a mesotrophic regime, responsible for the establishment of a chemosynthetic community under (sub)tropical conditions. The palaeo-depth of the depositional setting is estimated between 70 and 130 m. We further focused on decapod crustaceans that represent the first formally reported fossil decapod assemblage from the Granada province. The faunule consists of eight genera from two assemblages representing different palaeoenvironments. The assemblage of units 1 and 4 is dominated by the ghost shrimp “Callianassa” cf. almerai and accompanied by the hermit crab Petrochirus, whereas the assemblage from unit 3 includes the ghost shrimp Ctenocheles and the brachyuran crabs Raninoides, Calappa, Goneplax, Styrioplax, and Typilobus. Unit 2 does not yield any identifiable decapod remains. Styrioplax sp. represents the first occurrence of the genus outside the Central Paratethys, substantially expanding its palaeogeographical distribution. The decapod faunule from El Caracolar shows affinities with assemblages from the Proto-Mediterranean and Paratethys. This study provides a lithostratigraphic and palaeoenvironmental framework for further palaeontological studies in this unique Western Mediterranean outcrop.

Lithological control of land subsidence induced by groundwater withdrawal in new urban AREAS (Granada Basin, SE Spain). Multiband DInSAR monitoring

AbstractGround subsidence in the southeastern border of the Granada Basin (SE Spain) has been studied using remote sensing techniques. Over the last decades, the region has experienced a huge urban expansion, which has caused a substantial increase in water supply requirements. Water needs are exclusively met by groundwater by means of numerous pumping wells, which exploit a confined detrital aquifer of alluvial fan deposits with a heterogeneous facies distribution. A general piezometric level decline (up to 50 m) has been recorded in the aquifer during the past 30 years that has induced the generation of a subsiding area with oval shape oriented WNW‐ESE just where the new urban areas and pumping wells are located. Subsidence has been monitored by exploiting synthetic aperture radar (SAR) images from ENVISAT (2003–2009) and Cosmo‐SkyMed (2011–2014). A new approach, which combines A‐DInSAR and small‐area persistent scatterer interferometry (PSI) analysis, has been applied obtaining a good accuracy regarding temporal and spatial dimension of the subsidence. ENVISAT data (2003–2009) reveal subsidence rates up to 10–15 mm/year, and Cosmo‐SkyMed (2011–2014) values slightly lower; up to 10 mm/year. Temporal variations in the subsidence velocity are in accordance with the rainfall pattern and piezometric fluctuations in the aquifer. The sector with highest rates of subsidence does not correspond to the area with more intense groundwater exploitation but to the area with greater presence of clays in the confining layer of the aquifer. There is a clear lithological control in the spatial distribution of the ground subsidence. This work integrates detailed geological and hydrogeological data with differential SAR interferometry monitoring with the aim to better understand subsidence processes in detrital aquifers with small‐scale heterogeneity. Copyright © 2016 John Wiley &amp; Sons, Ltd.