SE Iberian Peninsula Research Articles

Model of Pleistocene geomorphological evolution in active Alpine neotectonics controlled margins in the western Mediterranean area: The case of SE Iberian Peninsula

At the northern tip of the Betic realm (SE Iberian Peninsula), some troughs (synclines) and elevations (anticlines) alternate, marking the present-day coastal lobed morphology of cape-bounded bays, where subsidence and uplift conditions prevailed, respectively. In this study, we were able to establish a clear coastal evolution. To this end, we considered the sedimentological and palaeoenvironmental conditions, the palaeogeographical reconstruction, and recent tectonics until Middle Pleistocene times (MIS 5) through the interpretation of onshore cores, raised marine deposits and geophysical profiles. In this regard, as reflected by both onshore and offshore information, there seems to be a stratigraphical gap from the end of the Pliocene to MIS 15 (Middle Pleistocene). In areas under uplift conditions, linked to tardive Alpine tectonics, the deposits of ancient shorelines and raised beaches were located at different post-depositional elevations, which were dated from odd MIS 15 to MIS 5 using amino acid racemization. Only deposits aged MIS 7 and MIS 5 are roughly at the present-day sea level or some meters above. In the troughs, which remain mostly as lagoons and salt marshes, subsidence did not allow the sedimentary record to be discerned. However, many borehole cores were recovered, attesting lagoonal, marsh, sabkha, or alluvial environmental conditions, which were usually unconnected from the sea. Micropaleontological and amino acid racemization dating revealed these cores to be of MIS15 to MIS5 age. Offshore seismic research revealed five erosive-bounded deposits that are stacked accretionary prisms corresponding to highstands between odd MIS 15 and MIS 5. In contrast, even MISs can be correlated to the erosive horizons that separated the seismic units, reflecting lowstands. In this regard, some bars, at a range of distances from the present-day coastline, protected wetlands from marine influence, allowing the development of diverse sub-environments under changing paleogeographical and paleoclimatological conditions.

Deterministic seismic hazard analysis from physics-based earthquake simulations in the Eastern Betics (SE Iberia)

The low frequency of large destructive earthquakes in the Eastern Betics (SE Iberian Peninsula), not recorded in the instrumental seismic catalog, complicate the estimation of the maximum ground motion that could be reached. Knowing the characteristics and behavior of these large seismic ruptures is crucial for the study of seismic hazard. In this work, we have used a physics-based earthquake simulator to generate a 100 kyr catalog of seismic ruptures associated with seismogenic faults bordering the quaternary Guadalentin and Bajo Segura basins. From these ruptures, we have selected maximum earthquake scenarios, and those associated with certain probabilities of exceeding a severe magnitude from the synthetic catalog. The estimation of maximum peak accelerations (PGA) by means of ground motion prediction equations include a possible site amplification that we have calculated from a detailed geotechnical classification of soils. According to the simulations, the modeled faults have the capacity to generate maximum earthquakes with magnitudes ranging MW 6.7–7.4. Densely populated urban areas located along the Guadalentin valley, such as Lorca, could be subject to site-dependent PGA values close to 0.6 g on the Alhama de Murcia fault trace. Similar ground motion would affect the coastline of SE Alicante province when evaluating the maximum simulated event in the Bajo Segura offshore fault. But already from magnitudes around MW ∼ 6, PGA estimations exceed critical values of 0.5 g at the south side of the Bajo Segura basin and the city of Murcia, highly dependent of ground-motion amplification induced by thick deposits of very soft and saturated soils. Our scenarios reflect that other factors such as fault geometry, kinematics and the capability observed in the simulations to generate multi-fault ruptures also affect the spatial distribution of maximum ground motion in this region. We expect that this evaluation could contribute as an improvement guideline for future strong motion prediction studies prior to the settlement of new urban infrastructures in the Eastern Betics.

What burned the forest? Wildfires, climate change and human activity in the Mesolithic – Neolithic transition in SE Iberian Peninsula

Climate variability such as higher or lower temperatures, changing precipitation patterns, shifts in plant communities and other climate-related changes have particularly affected areas with Mediterranean-type climates. A multi-proxy analysis including pollen, sedimentary charcoal, mineralogy and Summed Probability Distributions (SPD) of archaeological 14C dates, allowed the reconstruction of landscape change, geomorphological evolution and fire history at the Laguna de Villena, in the southeastern Iberian Peninsula, during the Mesolithic-Neolithic transition. The Villena paleolake was sensitive to Early Holocene and Middle Holocene regional climatic variability that included several arid phases (around 8.2 ka cal BP, 6.8 ka cal BP and 5.9 ka cal BP) according to geochemical and pollen data. During this period, landscape dynamics show the degradation of oak forests and expansion of pyrophytic pine forests and shrublands, as well as open spaces predominated by grasses. The charcoal record shows a decreasing trend of biomass burned from 8.5 ka cal BP onwards, although fire peaks occurred recurrently during the Early and Middle Holocene. The most intense phase of fire activity was experienced in the last millennia of the Early Holocene, with five fire episodes from 9.1 to 8.4 ka cal BP, coinciding with a phase of higher archaeological evidence in the area. A decrease in archaeological evidence coincides with a gap in fire episodes during the Early Holocene-Middle Holocene transition, suggesting an effect of the abrupt 8.2 ka cal BP event on human activity and on landscape dynamics. After 8.0 ka cal BP, lowerer biomass burned is explained by the configuration of a more open landscape due to the combination of climate (increasing aridity) and increasing human activities in the region. The mineralogical and palynological data highlighted the interaction between human activities, climate and fire dynamics. The sedimentary charcoal record evidenced how most of the fire peaks did not occur in the context of dry episodes, as often assumed, deriving on an anthropogenic explanation related to Early and Late Mesolithic burning practices during a phase of higher archaeological evidence in the Villena paleolake surroundings. Afterwards, combined agropastoral activities from the Early Neolithic onwards and increasing aridity during the Middle Holocene maintained the forest clearances, in the context of fire episodes characterised by decreased biomass burned. This study shows how Middle Holocene palaeoecological records reflect complex histories blending climate and anthropogenic processes that derived in major landscape changes explaining the origin of current landscapes.

Heinrich Stadial 1 continental sand dunes and Middle to Late Holocene paleosol sequences in SE Iberia: Implications for human occupation and site formation processes

Continental aeolian sandy deposits are common in the semi-arid Mediterranean biomes of the Iberian Peninsula. Very few studies, however, have addressed their chronology, formation, and evolution. In this work, we present the interdisciplinary study of the Villena dune field (SE Iberian Peninsula) for which sand dune-paleosol sequences spanning the Last Glacial to the Late Holocene have been documented. The surface area of the Villena dune field and the dune morphology were mapped using LIDAR elevation data. Three different stratigraphic sequences were analyzed through geochronology (OSL and AMS C14), micromorphology,soil chemistry, grain size and X-ray powder diffraction. The formation of the Villena dune field was OSL dated between 16.3 ± 0.6 and 14.97 ± 0.5 ka during the Heinrich Stadial 1 (HS1). Deflation, diffuse floods and runoff processes led to the removal of GS-1 and Early Holocene sediments from the stratigraphic sequences. Subsequently, discontinuous polycyclic soil sequences developed on the dune top sections from the Middle to the Late Holocene. Three main pedogenetic processes linked to palaeoenvironmental shifts –organic matter accumulation, calcium carbonate redistribution and periglacial features– were documented in two soil sequences registered in the stratigraphies investigated, which also included sedimentary hiatuses. Our work identified for the first time: (i) the formation of continental dune deposits spanning the HS1 on the Iberian Mediterranean region; (ii) sedimentary dynamics helping to understand Early to Late Holocene archaeological site formation processes in this area; and (iii) periglacial features dated the Little Ice Age.

First report of natural hybridisation between members of Teucrium subsect. Simplicipilosa and subsect. Polium: Teucrium × murcigerum (Lamiaceae), a new hybrid from southeastern Iberian Peninsula

A new nothospecies, Teucrium × murcigerum, is described which comes from the hybridisation between two species of section Polium: Teucrium murcicum (subsect. Polium) and Teucrium lanigerum (subsect. Simplicipilosa), both endemic to SE Iberian Peninsula. This appears to be the first report of natural intersubsectional hybridisation between T. subsect. Polium and subsect. Simplicipilosa. A morphological description is reported, emphasizing the main diagnostic characters which allow separation from its parental taxa. Additionally, data on its biology, ecology and distribution are also presented, as well as relationships to other related nothospecies produced by its parentals.

A Different Processing of Time-Domain Induced Polarisation: Application for Investigating the Marine Intrusion in a Coastal Aquifer in the SE Iberian Peninsula.

This study presents the developments regarding the time-domain induced polarisation method as a supporting tool for resistivity soundings during investigations of coastal detrital aquifers that are salinized by marine intrusion. The interpretation of resistivity measurements in such aquifers, which have variable hydrochemistry and lithology, involves uncertainties owing to the presence of low-resistivity lithologies, such as clays. To reduce these uncertainties, the use of other geophysical parameters is necessary; hence, this study focuses on induced polarisation since it can be measured simultaneously with resistivity. In detail, we propose the determination of induced polarisation using 1D techniques while developing a different algorithm for processing the induced polarisation data. The aim is to extend the results of this phenomenon, using, instead of chargeability, the concepts of polarisability and decay time, which are extracted from the decay curve, given that they represent more intrinsic properties of the various analyzed subsurface media. Results were obtained by applying this methodology to a Quaternary aquifer of the Costa del Sol in the SE Iberian Peninsula (in the province of Almería) during two different campaigns, one in mid-autumn and one late winter (i.e., in October and February, respectively) are presented. The results reveal the position of the saline front during each campaign while reflecting the seasonal movement of the marine intrusion.

Characterization of the shallow subsurface structure across the Carrascoy Fault System (SE Iberian Peninsula) using P-wave tomography and Multichannel Analysis of Surface Waves

The seismicity in the SE Iberian Peninsula is distributed parallel to the coast in a well-developed strike-slip fracture system known as the Eastern Betic Shear Zone (EBSZ). This work focuses on the characterization of the shallow subsurface structure of the Algezares-Casas Nuevas Fault, within the Carrascoy Fault System of the EBSZ. The Carrascoy Fault borders the Guadalentín Depression to the south, which is a densely populated area with extensive agricultural activity. Therefore, this faults system represents a seismic hazard with significant social and economic implications. We have constructed two velocity-depth models based on P-wave tomography and Multichannel Analysis of Surface Waves (MASW) acquired from seismic reflection data. The resulting velocity models have allowed us to interpret the first ~250m depth and have revealed: i) the thickness of the critical zone; ii) the geometry of the Algezares-Casas Nuevas Fault; iii) the depth of the Messinian/Tortonian contact and iv) the presence of blind thrusts and damage zones under the Guadalentín Depression. Our results have also helped us to estimate an apparent vertical slip rate of 0.66±0.06m/ky for the Algezares-Casas Nuevas Fault since 209.1±6.2ka. Our results provide a methodological and backflow protocol to study the shallow subsurface of active faults, complementing previous geological models based on paleoseismological trenches, and can be used to improve the seismic hazard assessment of tectonically active regions around the world.

Correction to: Reporting atmospheric CO2 pressure corrected results of stable carbon isotope analyses of cereals remains from the archaeological site of Peñalosa (SE Iberian Peninsula): agricultural and social implications

Correction to: Reporting atmospheric CO2 pressure corrected results of stable carbon isotope analyses of cereals remains from the archaeological site of Peñalosa (SE Iberian Peninsula): agricultural and social implications

Constitutive and Adaptive Traits of Environmental Stress Tolerance in the Threatened Halophyte Limonium angustebracteatum Erben (Plumbaginaceae).

Limonium angustebracteatum is a halophyte endemic to the E and SE Iberian Peninsula with interest in conservation. Salt glands represent an important adaptive trait in recretohalophytes like this and other Limonium species, as they allow the excretion of excess salts, reducing the concentration of toxic ions in foliar tissues. This study included the analysis of the salt gland structure, composed of 12 cells, 4 secretory and 8 accessory. Several anatomical, physiological and biochemical responses to stress were also analysed in adult plants subjected to one month of water stress, complete lack of irrigation, and salt stress, by watering with aqueous solutions of 200, 400, 600 and 800 mM NaCl. Plant growth was inhibited by the severe water deficit and, to a lesser extent, by high NaCl concentrations. A variation in the anatomical structure of the leaves was detected under conditions of salt and water stress; plants from the salt stress treatment showed salt glands sunken between epidermal cells, bordered by very large epidermal cells, whereas in those from the water stress treatment, the epidermal cells were heterogeneous in shape and size. In both, the palisade structure of the leaves was altered. Salt excretion is usually accompanied by the accumulation of salts in the foliar tissue. This was also found in L. angustebracteatum, in which the concentration of all ions analysed was higher in the leaves than in the roots. The increase of K+ in the roots of plants subjected to water stress was also remarkable. The multivariate analysis indicated differences in water and salt stress responses, such as the accumulation of Na and Cl, or proline, but K+ homeostasis played a relevant role in the mechanism of tolerance to both stressful conditions.

Geophysical Imaging of the Critical Zone along the Eastern Betic Shear Zone (EBSZ), SE Iberian Peninsula

The critical zone (CZ) represents the most-shallow subsurface, where the bio-, hydro-, and geospheres interact with anthropogenic activity. To characterize the thickness and lateral variations of the CZ, here we focus on the Eastern Betic Shear Zone (EBSZ), one of the most tectonically active regions in the Iberian Peninsula. Within the EBSZ, the Guadalentín Depression is a highly populated area with intensive agricultural activity, where the characterization of the CZ would provide valuable assets for land use management and seismic hazard assessments. To achieve this, we have conducted an interdisciplinary geophysical study along the eastern border of the Guadalentín Depression to characterize the CZ and the architecture of the shallow subsurface. The datasets used include Electrical Resistivity Tomography (ERT), first-arrival travel time seismic tomography, and multichannel analysis of surface waves (MASW). The geophysical datasets combined help to constrain the high-resolution structure of the subsurface and image active fault systems along four transects. The resulting geophysical models have allowed us to interpret the first ~150 m of the subsurface and has revealed: (i) the variable thickness of the CZ; (ii) the CZ relationship between the fault zone and topographic slope; and (iii) the differences in CZ thickness associated with the geological units. Our results provide a method for studying the shallow subsurface of active faults, complementing previous geological models based on paleo-seismological trenches, and can be used to improve the CZ assessment of tectonically active regions.

Characterization of the Spanish juniper population of El Peñón de Alamedilla (Granada, Spain): conservation status and protection proposal

Aims of the study: To characterize the southernmost Spanish Juniper (Juniperus thurifera L.) population in Europe, a relict species of the tertiary flora.Area of study: El Peñón de Alamedilla, Los Montes region (Granada, Spain).Material and Methods: A census and geo-referencing of the individuals in the population was carried out, together with the determination of the population structure, inference of the potential extension of the population, and discussion of the risk faced by the population.Main results: A total of 899 individuals were located in mainly 128 ha from 806 to 888 m a.s.l. We found 50.6% adults, 35.7% saplings and 13.6% juveniles. Sexing on the adults showed a 60% of male feet compared to 39.1% of females (0.9% undifferentiated). 47% of the population has a basal diameter less than or equal to 50 mm. A 74.11% of the population was in grasslands + scrubs, and only 5.3% of the specimens were in arable lands. All individuals are on privately owned land.Research highlights: The characterization of this southernmost Spanish Juniper population suggests a good viability and resilience, though there is also a high risk of inbreeding, with the population being able to go into genetic drift, which is critical for successful reproduction and may easily jeopardize its conservation efforts. This species is not protected enough in Andalusia and conservation measures should be taken.Keywords: Juniperus thurifera, SE Iberian Peninsula, relict population, Natura 2000 Network.

Physics‐Based Earthquake Simulations in Slow‐Moving Faults: A Case Study From the Eastern Betic Shear Zone (SE Iberian Peninsula)

AbstractIn regions with slow‐moving faults, the incompleteness of earthquake and fault data complicates the study of seismic hazard. The instrumental and historical seismic catalogs cover a short period compared with the long‐time interval between major events. Paleoseismic evidence allows us to increase the time frame of actual observations, but data is still scarce and imprecise. Physics‐based earthquake simulations overcome the limitations of actual earthquake catalogs and generate long‐term synthetic seismicity. The RSQSim earthquake simulator used in our study reproduces the earthquake physical processes based on a 3D fault model that contains the kinematics, the long‐term slip rates and the rate‐and‐state friction properties of the main seismogenic sources of a region. The application of earthquake simulations to the Eastern Betic Shear Zone, a slow fault system at southeastern Spain, allows the compilation of 100 kyr‐synthetic catalogs ofMW > 4.0 events. Multisection earthquakes and complete ruptures of some faults in this region, preferentially on strike‐slip dominant ruptures, are possible according to our simulations. The largestMW > 6.5 events are likely as a result of jumping ruptures between the Carboneras and the Palomares faults, with recurrence times of < 20,000 years; and less frequently between the Alhama de Murcia and the Los Tollos faults. A great variability of interevent times is observed between successive synthetic seismic cycles, in addition to the occurrence of complex co‐ruptures between faults. Consequently, the occurrence of larger earthquakes, evenMW ≥ 7.0, cannot be ruled out, contrasting with the low to moderate magnitudes recorded in the instrumental and historical earthquake catalog.

Complete Strain Record of a Highly Asymmetric Shear Zone: From Fault Core Gouges to Surface Rupture of Historical Earthquakes in the Alhama de Murcia Fault (SE Iberian Peninsula)

Complete Strain Record of a Highly Asymmetric Shear Zone: From Fault Core Gouges to Surface Rupture of Historical Earthquakes in the Alhama de Murcia Fault (SE Iberian Peninsula)

Long-term monitoring of the Iberian ibex population in the Sierra Nevada of the southeast Iberian Peninsula

This dataset provides long-term information on the presence of the Iberian ibex (Capra pyrenaica hispanica Schimper, 1848) in Sierra Nevada (SE Iberian Peninsula). Data on the abundance and demographic structure of the Iberian ibex population were compiled over the last three decades. Transects were laid out to record different variables such as the number of individuals sighted, the perpendicular distance of each group of Iberian ibex to the transect line and sex as well as age of individuals in the case of males. These data enabled the calculation of population parameters such as density, sex ratio, birth rate, and age structure. These parameters are key for Iberian ibex conservation and management, given that Sierra Nevada harbours the largest population of this species in the Iberian Peninsula. The data set we present is structured using the Darwin Core biological standard, which contains 3,091 events (582 transect walk events and 2,509 group sighting events), 5,396 occurrences, and 2,502 measurements. The occurrences include the sightings of 11,436 individuals (grouped by sex and age) from 1993 to 2018 in a total of 88 transects distributed along Sierra Nevada, of which 33 have been continuously sampled since 2008.

Application of the analytic model of general triclinic transpression with oblique extrusion to an active deformation zone: The Alhama de Murcia Fault (SE Iberian Peninsula)

We have applied the analytic model of general triclinic transpression with oblique extrusion to an active shear zone in southeastern Spain. This study opens a new methodological approach in the study of active fault zones. We are able to constrain the triclinic transpression model with absolute measures of active deformation, such as GPS velocity gradients, and have exhaustively explored the predictions of the model and compared them to the orientation data of field kinematic markers (fault-slip data and reorientation of fold hinges during progressive deformation), GPS data and the kinematic study of the fault gouge that is developed at the Alhama de Murcia Fault. The combined analysis allows the values of the kinematic vorticity number, the orientation of the vorticity vector, the orientation of the local and regional convergence vectors, the angle of extrusion in the shear zone and the amount of extrusion to be constrained. The results point to a highly partitioned heterogeneous shear zone with domains deforming in response to the same boundary conditions but are displaying different kinematic responses that reflect both their intrinsic properties and geometric effects related to competency contrasts. We propose that the Alhama de Murcia Fault is an incompletely coupled fault zone with two different domains: a low competency domain comprising the fault gouge, ductilely deformed, with low vorticity values, which probably experienced a steady-state, aseismic slip that reflects regional convergence vectors (convergence Eurasia–Nubia); and a domain outside of the fault gouge with episodic brittle failure, with higher vorticity values and showing convergence vectors which are parallel to the local convergence vectors calculated from the GPS velocity field.

Morphological variability patterns in the Balearites-Pseudothurmannia genera boundary (Ammonoidea, late Hauterivian): taxonomic and biostratigraphic implications

As for many other ammonoid groups, the Hauterivian family Crioceratitidae has been traditionally approached from a strictly typological viewpoint, leading to considerable taxonomic oversplitting. Balearites angulicostatus (d’Orbigny, 1841) and Pseudothurmannia ohmi (Winkler, 1868) are two successive species within this lineage, which are used as index species in biostratigraphy. In order to clarify the taxonomic position of the two aforementioned species, the present study carries out morphometric analyses on 111 stratigraphically controlled specimens from the Arroyo Gilico section (SE Iberian Peninsula), enabling us to conclude that the diagnoses of both species should be broadened to encompass the continuous morphological variations occurring within their populations. A phenotypic variability model among eight extreme poles is described for B. angulicostatus, whereas P. ohmi ranges between two extreme poles. The detailed study of shell morphology through time recognizes the evolutionary changes between the two species: anagenetic processes such as the increase of whorl height growth rate and tachymorphosis of ontogenetic stages, coupled with punctuated changes such as the loss of heteromorphic coiling and an allometric hypermorphosis. Some of these may be inherent to the variation of the species themselves, but others such as the loss of heteromorphism seem to be related to palaeoenvironmental factors such as changes in nutrient supply to the sea.

First evidence of paleoearthquakes along the Carboneras Fault Zone (SE Iberian Peninsula): Los Trances site

Seismogenic faults that have not produced historical large earthquakes remain unnoticed and, thus, are dangerously left out from seismic hazard analyses. The seismogenic nature of the Carboneras Fault Zone, a left-lateral strikeslip fault in the Eastern Betic Shear Zone (southeastern Spain), has not been fully explored to date in spite of having a morphological expression equivalent to the Alhama de Murcia Fault, a seismogenic fault in the same tectonic system. This study provides the first paleoseismic evidence of the seismogenic nature of the CarbonerasFault Zone, based on the analysis of 3 trenches at Los Trances site, on the northwestern edge of the La Serrata Range. Cross cutting relationships and numerical dating, based on radiocarbon, thermoluminescence and U-series, reveal a minimum of 4 paleoearthquakes: Paleoearthquake1 (the oldest) and Paleoearthquake2 took place after 133ka, Paleoearthquake3 occurred between 83–73ka and Paleoearthquake4 happened after 42.5ka (probably after 30.8ka), resulting in a maximum possible average recurrence of 33ka. This value, based on a minimum amount of paleoearthquakes, is probably overestimated, as it does not scale well with published slip-rates derived from offset channels or GPS geodetical data. The characterization of this fault as seismogenic, implies that it should be considered in the seismic hazard analyses of the SE Iberian Peninsula.

Reporting atmospheric CO2 pressure corrected results of stable carbon isotope analyses of cereals remains from the archaeological site of Peñalosa (SE Iberian Peninsula): agricultural and social implications

The practice of agriculture across the Mediterranean basin has had significant social and economic consequences, including the development of social inequalities. To inform on plant water status and thus on agricultural management techniques and environmental conditions during the first half of the second millennium BCE, we measured stable carbon isotopes in a set of 280 seeds of Hordeum vulgare L. and Pisum sativum from the archaeological site of Penalosa (Banos de la Encina, southern Iberian Peninsula). The ranges in stable carbon isotope values for archaeological samples were wider than those observed for modern reference samples collected in 2014 and 2015, suggesting that archaeological samples experienced more varied water status conditions. This variability was associated with the location of the seeds within the site and could be a consequence of the cultivation of different plots and/or from temporal variations in local environmental conditions. For absolute comparisons of water status between modern and past samples, we introduced a novel correction to account for temporal changes in the concentration of atmospheric CO2 in addition to the usual adjustment that accounts for the variability in atmospheric CO2 stable carbon isotope values. This comparison showed that past samples had greater water availability than modern references, and thus, irrigation or intentional selection of naturally irrigated soils was practiced at the site.

Some colored travertines from the Betic Range (SE Iberian Peninsula): their geological setting and petrophysical properties

The Betic Range contains several colored travertine deposits which were formed during the last stage of the post-tectonic Tertiary-Quaternary (Pleistocene) basin refill. Associated with active faults, these travertines are quarried in Alhama de Almería, Albox (Almería) and Baños de Mula (Murcia) for subsequent use as ornamental stone. The aim of this study was to characterize their facies and physical properties in order to establish their suitability for use as an ornamental stone. The main facies was banded (1-10 cm), and the travertines presented variable porosity ranging from 5-15%. Porosity is related to travertine texture: a) fairly homogeneous microporosity, with a mode between 0.005 and 0.05 µm, is linked to micritic carbonate; and b) a porosity mode varying widely from 0.05 to 2 µm is associated with larger crystals. A characteristic feature of these travertine deposits was their macroporosity of variable size and distribution. The coefficient of capillary absorption was highly anisotropic and presented very different magnitudes in the different travertines studied. A minimum value of 1.42 (g/m2 s0.5) was observed in the commercial Red Alhama travertine, in an oblique direction to the structure, while the maximum value of 10.71 (g/m2 s0.5) was found in Albox travertine deposits, in a parallel direction to the structure. Strength was markedly anisotropic, attaining compressive strength values as high as 68 MPa in the direction perpendicular to the bedding planes. When cut in this direction, the travertines studied yield good quality ornamental stone within the category of commercial marble.

Lateral slip rate of Alhama de Murcia fault (SE Iberian Peninsula) based on a morphotectonic analysis: Comparison with paleoseismological data

To define the seismic potential of the left-lateral strike-slip Alhama de Murcia fault (SE Iberian Peninsula), we calculated its slip rate by measuring offset linear features of known age using a morphotectonic analysis. The Lorca-Totana section of the fault yielded a minimum slip rate of 1.0 ± 0.2 mm/a for the past 30 ka, based on a channel whose age is estimated by OSL technique. The minimum left-lateral slip rate of the Goñar-Lorca section is 1.6–1.7 mm/a for the past 200 ka, based on eight offset surface channels, previously mapped alluvial fans dated by TL, and by new U-series dating of pedogenic carbonate. The U-series technique was used here for first time in the Iberian Peninsula to date small amounts (mg) of pedogenic carbonate. According to the newly estimated slip rate values, the Alhama de Murcia fault is one of the most active faults in the Eastern Betics Shear Zone. These values are larger and have fewer uncertainties in comparison with previous slip rates estimations. In the Lorca-Totana section, the new lateral slip rate is compared with a slip rate calculated by means of a paleoseismic study showing good agreement between the values obtained with the two approaches. We encourage the combination of paleoseismology and morphotectonic analysis to obtain reliable slip rates for faults with scarce evidence of late Holocene slip.