Speleothems In Caves Research Articles

Corrosion of calcite speleothems in epigenic caves of Moravian Karst (Czech Republic)

Corrosion processes were studied in epigenic caves of the Moravian Karst (MK). Samples of naturally corroded speleothems and carbonate rocks collected in various MK caves were compared with limestone and calcite standards that were corroded under well-controlled conditions in the laboratory. Two stages of corrosion were distinguished: (1) an early stage of pitting and linear corrosion predisposed by point and line defects in the standards, and (2) an advanced stage characterized by deep corrosion of the entire standard surface. During the second stage, the internal structure of the corroded substrate remained partially preserved, however, if the water was extremely aggressive, the corrosion progressed to depth en-bloc regardless of the structure. In this paper, we (1) proposed a new corrosion mechanism based on the binding of aqueous calcium by clays and tested it experimentally in the cave, (2) characterized conditions that generally favor the formation of aggressive waters (water undersaturated with calcite) into seven categories incorporating them into a conceptual model of the karst vertical profile, and (3) discussed anthropogenic influences on these processes.

Environmental changes in Sorbas arid region (Southern Spain) during MIS 5a inferred from a carbonate flowstone from a gypsum cave

Present climate conditions impede the formation of calcite speleothems in the gypsum caves of the semi-arid region of Sorbas (Southern Spain). However, U-Th dating reveals the uninterrupted deposition of a 46 mm-thick carbonate flowstone in the Sorbas caves from ∼78 to ∼71 ka, during Marine Isotope Stage (MIS) 5a. This indicates that the area was vegetated during this period, producing biogenic CO2 in soils necessary for the underground deposition of the speleothem, which contrasts with the current unvegetated landscape. During MIS 5a, rainfall recharged the karst aquifer, leading to cave seepage. The development of soils and persistent water infiltration suggests a higher precipitation/evapotranspiration ratio with respect to the present, which was likely favored by lower regional temperatures and a different annual rainfall regime. δ18O and δ13C analyses testify that the speleothem recorded climate pulses synchronous, and structurally similar, with Greenland interstadial and stadial periods, with relatively wetter conditions recorded during interstadials 21.1, 20 and 19.2, and drier periods during stadials 21.1 and 20. This demonstrates that the climate in the desert-like environment of Sorbas is sensitive to inter- and intra- hemispherical triggers, such as the extent of Northern ice sheets and the Atlantic meridional overturning circulation. Interstadials (stadials) were also characterized by a higher (lower) Atlantic/Mediterranean moisture source ratio. For the first time, we show that carbonate speleothems formed in arid gypsum caves can record reliable palaeoenvironmental information spanning multiple millennia, procuring proxies for detailed palaeoclimate reconstructions. Such speleothems are thus excellent candidates for understanding past climate dynamics and patterns in desert-like gypsum terrains.

Speleothems in sandstone crevice and boulder caves of the Elbe River Canyon, Czech Republic

A variety of speleothems are present in crevice and boulder caves developed in Cretaceous sandstones of the Elbe River Canyon in northern Czech Republic. A set of complementary instrumental mineralogical methods was applied to characterize the speleothems and cave dripwaters, including X-ray powder diffraction, scanning electron microscopy and microanalysis, Raman spectroscopy and optical emission spectrometry. Four morphological types were distinguished and characterized in terms of their mineral and chemical composition: 1, rusty brown mud-dominated coatings with micro-gours, composed of a mixture of clay minerals; 2, white “chalky” coatings (moonmilk) composed of calcite with minor gypsum; 3, cauliflower-shaped coralloids composed of calcite and silica in a layered structure, with gypsum layers in apical parts; 4, knob coralloids, dark gray-brown with smooth surfaces and distinctly layered structures, composed of silica (quartz, opal-A) and Si–Al phases (kaolinite) and including phosphate-rich laminae (sasaite, vashegyite, taranakite). Only modest microbial mediation of silica precipitation was observed in cauliflower-shaped coralloids while no clear signs are present in knob coralloids despite organic enrichment in the topmost layer. White “chalky” coatings and cauliflower-shaped coralloids precipitated from weakly acidic Ca-, Mg- and sulphate-rich deeper sandstone percolates. These forms are probably still active, much like the micro-gours, produced by particulate clay deposition. Formation of knob coralloids combined clay deposition and the dominant silica precipitation from pore waters similar to the present shallow acidic percolates under changing climatic conditions, probably in the Pleistocene. It was favored by specific rock lithology (quartzose sandstone with kaolinite admixture), which explains the scarcity of similar forms in sandstone caves. Concentration of knob coralloids along protruding vertical edges and the presence of wind-guided forms suggests that silica precipitation was driven by evaporation under a constant air flow.

The potential of Ojo de Valjunquera cave (NE of Iberia) sediments for paleoflood reconstructions

Speleothems and detrital deposits in caves are excellent archives of cave flood events but are still poorly exploited. In this study we evaluate, the potential of the Ojo de Valjunquera (Zaragoza, NE Spain) for the study of past floods based on geomorphological, topographical, hydrological, and chronological data. The cave comprises two subhorizontal levels. The lower level consists of a main horizontal conduit including six siphons. This level is connected to the upper one by shafts and ramps. That situation, together with the constrictions of the gallery in the lower level, favours the water rise during rainfall events. The upper level is characterized by a larger presence of speleothems and detrital sequences compared to the lower level. Current observations indicate that water can rise by ~9 m in some cave sectors during rainfall episodes >60 mm, although the hydraulic head rise is not homogeneous along the cave, depending on the section's morphology. The stalagmites and detrital sequences hosted in the upper gallery most likely contain evidence of extreme events of rainfall. However, geomorphological and sedimentological evidences also suggest that the cave outlet could have been blocked in the past by sediments, favouring the water rise to high places usually not affected by regular floods. The detrital sequences located in lower positions with respect to the cave entrance show a higher proportion of sandy sediments than those located in the higher sectors related to the water energy during the flood. Stalagmites show clean carbonate alternating with well-defined detrital layers. These detrital layers vary in thickness: the thinner ones are related to small floods, whereas the thicker ones are connected to large floods. Two important historical floods (1709 and 1755 CE) occurred in the area that coincide with distinct detrital layers recorded in the stalagmites. All these observations suggest that Ojo de Valjunquera cave contains an important paleoflood archive based on speleothems and detrital deposits during the Holocene.

On the genesis of aluminum-rich speleothems in a granite cave of NW Spain

Granite massifs often contain caves, with dimensions ranging from a few meters up to 1,000 m, also referred to as pseudokarst. The speleothems in such caves are mostly composed of either Si-rich (commonly opal-A) or Al-rich authigenic mineraloids. Whereas the formation and geochemical composition of opal-A biospeleothems have been studied and are fairly well understood, knowledge on the Al-rich analogues is scarce. This work reports for the first time a study on the composition, accretion process, age and growth rate of an Al-rich speleothem type flowstone from the A Trapa Cave System (Galicia, NW Spain), developed in a granite cave. To understand the growth process, trickling water was analyzed and the deposition environment inside the cave was characterized. We found that the speleothems are alternating Si- and Al-rich layered deposits formed between 1,635 ± 75 and 1,243 ± 58 cal BP by percolating water that carries underground mineral grains, dissolved ions, and organic matter from soil and the weathered bedrock above the cave.

Speleothems in quartz-sandstone caves of Ponta Grossa municipality, Campos Gerais region, Paraná state, southern Brazil

The present communication characterizes and discusses the genesis of cave speleothems developed in Furnas Formation (Silurian-Devonian) and Vila Velha sub-unit (Campo Mourão Formation, Upper Carboniferous) quartz-sandstones, in southern Brazil. The research, which involved stratigraphic and petrographic studies, was conducted to identify the faciological context of occurrence of these features, and to determine, through different analytical methods, their mineralogical composition and porosity, and also the action of microbial markers on the genesis of these secondary mineral deposits. The speleothems were classified into six types based on form, composition and genesis: (1) arborescent (coral), (2) mushroom-shaped, (3) stalactitic, (4) stalagmitic, (5) columnar with horizontal/ascending growth, and (6) fibrous. In response to substrate permoporosity, speleothems develop on all sandstone facies of the study area, mainly in sites controlled by bedding, stratification and fracturing planes. They are less frequent, however, in conglomerate and silty-clayey layers of the Furnas Formation, being composed mainly of silica (opal-A and cryptocrystalline silica) and kaolinite, with lesser contribution of gypsum and amorphous iron oxides associated with goethite and hematite. Detritic minerals such as quartz and muscovite also take part in the composition of these features. Plant and invertebrate fragments were identified, including biosignatures and microorganisms capable of favoring precipitation of silica (possibly cyanobacteria and diatom) and iron oxide (possibly Gallionella ferruginea). Such biosignatures and extracellular polymeric substances (biofilms) associated with speleothems are evidence of organomineralization, also known as biologically induced mineralization. The results, which indicate biological action on the genesis of speleothems, raise further discussion on the influence of microorganisms on the dissolution and precipitation of silica and kaolinite in the region.

Exotic sulphate and phosphate speleothems in caves from eastern Amazonia (Carajás, Brazil): Crystallographic and chemical insights

This study investigates the mineral, crystallographic and chemical characteristics of sulfate and phosphate speleothems and the physicochemical conditions that enabled their development in caves in the banded iron formations and lateritic duricrusts of the Carajás region, in eastern Amazonia, Brazil. The X-ray powder diffraction (XRD), Rietveld refinement, scanning electron microscopy (SEM), electron microprobe (EMPA), thermogravimetry, as well as Raman, infrared, and Mössbauer spectroscopy techniques were used in this investigation. The chemical composition analyses of the guano and cave dripping water were performed by atomic absorption spectroscopy (AAS), spectrophotometry and multi-parameter probe. The results of the analyses revealed aluminite, felsőbányaite, jarosite, spheniscidite, phosphosiderite and amorphous phosphatic material in coralloid type speleothems while spheniscidite, phosphosiderite and strengite were identified in stalactite type speleothems. These minerals are the product of the direct chemical reaction of the bat guano, urine and bones accumulation (with K+, Na+, Ca2+, Mg2+, NH4+) and the iron and aluminum supplied by the lateritic duricrusts from the walls, ceilings and floor of the caves, into a mixture of sulfates and phosphates.

Biomineralization Potential of Bacillus subtilis, Rummeliibacillus Stabekisii and Staphylococcus Epidermidis Strains In Vitro Isolated from Speleothems, Khasi Hill Caves, Meghalaya, India

ABSTRACTMicroorganisms were isolated and identified from speleothems at Khasi hill caves, Meghalaya. The aim was to understand their biomineralization potential. Analyses of the speleothems from Krem Soitan, Krem Mawpun, and Krem Lawbah using scanning electron microscope (SEM) showed evidences for microbe–mineral interactions. SEM showed microbial reticulate and beaded filaments, cells, fiber calcites, and clusters of coccoid-like structures. A total of 113 bacterial strains were isolated and identified by a combination of conventional and molecular based tools. 105 strains that were sequenced belonged to the genus: Bacillus, Rummeliibacillus, Staphylococcus, and Brevibacterium. The BLASTn sequence search of 16S rRNA sequences with the National Centre for Biotechnology Information database to establish the identity of the strains yielded similarity scores of ≥99% with the respective organisms. The strains were identified as Bacillus simplex, Bacillus gaemokensis, Bacillus subtilis, Bacillus thuringiensis, Bacillus albus, Bacillus cereus, Bacillus anthracis, Bacillus weihenstephanensis, Rummeliibacillus stabekisii, Bacillus wiedmannii, Staphylococcus epidermidis, Rummeliibacillus pycnus, Kurthia zopfii, and Brevibacterium frigoritolerans. These strains were tested for biomineralization on B-4 medium. Five strains (B. subtilis, R. stabekisii, Staphylococcus epiderdimis, B. cereus, and B. wiedmannii) had the capability to precipitate biominerals in vitro. B. subtilis, R. stabekisii, and S. epidermidis precipitated 0.24, 0.36, and 0.35 g/L of biominerals at 22°C at the end of the four week experiment period. These strains increased the pH of the medium from 7 to 8.95. The precipitated biominerals were imaged using an ultra-high resolution field emission SEM. X-ray diffraction of the biomineral precipitated by R. stabekisii showed that it was composed of vaterite and jungite. Whereas S. epidermidis showed that it was composed of calcite, vaterite, and jungite. B. subtilis produced small, circular calcite crystals. This is the first comprehensive report on the possible evidences about the role of R. stabekisii and S. epidermidis in calcite precipitation isolated from speleothems in the Indian caves. These results allow us to postulate that the identified strains have biomineralization potential. Further evidences of the coexistence of exopolysaccharides, whisker fiber calcites, microbial filaments, and coccoid-like forms point to biogenic inputs in the cave mineral formations.

Eco-friendly Remediation of Lampenflora on Speleothems in Tropical Karst Caves

Eco-friendly Remediation of Lampenflora on Speleothems in Tropical Karst Caves

Phosphate speleothems in caves developed in iron ores and laterites of the Carajás Mineral Province (Brazil) and a new occurrence of spheniscidite

Phosphate speleothems in caves developed in iron ores and laterites of the Carajás Mineral Province (Brazil) and a new occurrence of spheniscidite

Study and remediation of environmental problems caused due to the growth of algae in speleothems of calcareous caves adapted for tourism- a case of success in Spain

Caves, mainly those located on calcareous rocks are one of the best examples of geological heritage around the world. Their care and preservation should be a priority for the authorities dealing with the environment and culture. In addition to the dryness and discoloration wrought about by algae and bacteria in the speleothems, huge amounts of visitor traffic to the caves pose an additional burden, which is harmful to the conservation of the calcareous structures present inside the caves. This article is a compendium of the results and the on-going studies under the Rehabilitation Project of Ortigosa de Cameros system caves. This project deals with the assessment and clean-up of exogenous algal communities that have deteriorated the speleothems in the tourist caves located in the municipality of Ortigosa de Cameros [Spain].In order to choose an appropriate cleaning agent for the speleothems, a bibliographic review was conducted. Several methods of remedying including the use of mechanical as well as chemical methods have been discussed. After selecting the agent of choice for the clean-up of the speleothems, laboratory and in situ tests were performed using the same. Based on the results of these initial studies, the same methodology was applied to all areas affected by the "lampenflora". Care was taken that the selected methodology did not cause any damage to the fauna that inhabits these caves and nor did it leave a perceptible trace. An economical and environmental friendly method is still required to eliminate the algal mat that covers the speleothems of many caves adapted for tourist visits, in order to preserve our subterranean geological heritage throughout the world.

Evidence of Holocene surface and near-surface palaeofires in karst caves and soils

Black deposits covering speleothems, cave walls and floors in Postojna Cave and Predjama Cave (SW Slovenia), and charcoal found in soil outside the Postojna Cave, were studied in order to establish their origin and age. SEM/EDS analysis of these deposits from both caves indicated that they are charred plant remains, very similar to oxidised charcoal in soil. Stable carbon isotope δ13C values of −29.41‰ (Črna Jama, P1), −26.9‰ (Predjama), and −25.1‰ (charcoal in soil) confirm their origin from biomass burning. Radiocarbon dating from Postojna Cave (Črna Jama (P1) 8394±35calyrB.P. and Pisani Rov 8235±25calyrB.P.) suggests that the oldest analysed black deposits formed in the Early Holocene (Mesolithic). The age is consistent with soil charcoal found at 1m depth in the surrounding area. Black deposits from Predjama were dated to 4095±25calyrB.P. (Eneolithic) and were caused by burning fires at the cave entrance, as supported by archaeological remains. Prehistoric (2375±20calyrB.P.) charcoal from the upper part of the soil profile (0.5 to 0.6m) and historic (1240±29calyrB.P. or 745calyrCE) black deposits from Postojna Cave (Črna Jama, P2) are related to forest fires, which are most likely human-induced. We interpret the oldest dated black deposits in Postojna Cave as traces of Early Holocene natural forest fires, since fire activity inside Črna Jama and Pisani Rov is not supported by archaeological remains. Favourable cave entrance morphology and microclimate allowed smoke to enter the cave during the winter period and deposit on speleothems. But an anthropogenic cause of forest fires cannot be excluded, since there are well-documented Mesolithic archaeological cave sites located close to the area. The study shows that black deposits on speleothems in caves are an important palaeoenvironmental record and proxy for Holocene climate.

Biomineralization Abilities of Cupriavidus Strain and Bacillus subtilis Strains In Vitro Isolated from Speleothems, Rani Cave, Chhattisgarh, India

ABSTRACTIn vitro culture experiments using three bacterial strains CSJC1, CSJC2, and CSJC3 isolated from speleothems, Rani cave, Chhattisgarh, India, were studied to examine their biomineralization potential. These speleothems showed high microbial cell enumerations on nutrient agar and iron agar (9 × 104 CFU/g) followed by thiosulfate agar (7 × 104 CFU/g), and 60 diverse strains were isolated. The BLASTn sequence search of 16S rRNA sequences with the NCBI database to establish the identity of CSJC1, CSJC2, and CSJC3 strains yielded similarity scores of ≥99% with the respective organisms, and the strains were identified as CSJC1 – Bacillus sp., CSJC2 – Cupriavidus sp., CSJC3 – Bacillus sp. The phylogenetic analysis of CSJC2 strain suggests that it formed a separate major cluster with Cupriavidus sp. and Cupriavidus necator. The phylogenetic analysis of CSJC1 and CSJC3 strains revealed that it formed a major cluster with several strains of Bacillus sp. and Bacillus subtilis. The biominerals induced by Cupriavidus sp. CSJC2 strain imaged with an ultra high-resolution field emission scanning electron microscope (FE-SEM) were seen as calcified coccoid shells that transformed into calcified dumbbells. FE-SEM imaging of biominerals induced by B. subtilis CSJC1 and CSJC3 tested both on B4 media and sheep blood agar individually showed that the precipitates formed calcified dumbbells that were almost similar but not identical phenotypically, indicating that strain-specific morphologies and crystal formation is easier when Ca is present in the media. This is the first comprehensive report on the possible evidences about the role of Cupriavidus sp. in calcite precipitation isolated from speleothems in the Indian caves. These results allow us to postulate that the identified strains may have a role in the biogenic influences in mineral formations at Rani cave.

Characterization of bacterial diversity associated with calcareous deposits and drip-waters, and isolation of calcifying bacteria from two Colombian mines

Bacterial carbonate precipitation has implications in geological processes and important biotechnological applications. Bacteria capable of precipitating carbonates have been isolated from different calcium carbonate deposits (speleothems) in caves, soil, freshwater and seawater around the world. However, the diversity of bacteria from calcareous deposits in Colombia, and their ability to precipitate carbonates, remains unknown. In this study, conventional microbiological methods and molecular tools, such as temporal temperature gradient electrophoresis (TTGE), were used to assess the composition of bacterial communities associated with carbonate deposits and drip-waters from two Colombian mines. A genetic analysis of these bacterial communities revealed a similar level of diversity, based on the number of bands detected using TTGE. The dominant phylogenetic affiliations of the bacteria, determined using 16S rRNA gene sequencing, were grouped into two phyla: Proteobacteria and Firmicutes. Within these phyla, seven genera were capable of precipitating calcium carbonates: Lysinibacillus, Bacillus, Strenotophomonas, Brevibacillus, Methylobacterium, Aeromicrobium and Acinetobacter. FTIR and SEM/EDX were used to analyze calcium carbonate crystals produced by isolated Acinetobacter gyllenbergii. The results showed that rhombohedral and angular calcite crystals with sizes of 90μm were precipitated. This research provides information regarding the presence of complex bacterial communities in secondary carbonate deposits from mines and their ability to precipitate calcium carbonate from calcareous deposits of Colombian mines.

Dating of speleothems in non-karst caves - methodological aspects and practical application, Polish Outer Carpathians case study

Gravitational mass movements (landslides) have been one of the most efficient processes contributing to the morphogenesis of the Outer Carpathians formed of flysch, siliciclastic-clayey rocks. Such processes often produce non-karst caves in sandstones. Dating of calcite speleothems developed in caves hosted by sandstone with calcareous cement seems to be a suitable method to reconstruct phases of slope evolution in this region. The paper discusses the usefulness of radiocarbon (14 C) and U-series dating of speleothems in non-karst caves in the reconstruction of mass movement chronology and evaluates possible reasons for discrepancies between both methods. The obtained speleothem age data are used to improve the existing knowledge on the chronology of mass movements during the Late Glacial and Holocene in the flysch Carpathians.

Paleoflood events recorded by speleothems in caves

ABSTRACTSpeleothems are usually composed of thin layers of calcite (or aragonite). However, cemented detrital materials interlayered between laminae of speleothemic carbonate have been also observed in many caves. Flowstones comprising discontinuous carbonate layers form due to flowing water films, while flood events introduce fluviokarstic sediments in caves that, on occasion, are recorded as clayey layers inside flowstones and stalagmites. This record provides a potential means of understanding the frequency of palaeofloods using cave records. In this work, we investigate the origin of this type of detrital deposit in El Soplao Cave (Northern Spain). The age of the lowest aragonite layer of a flowstone reveals that the earliest flood period occurred before 500 ka, though most of the flowstone formed between 422 +69/‐43 ka and 400 +66/‐42 ka. This suggests that the cave was periodically affected by palaeoflood events that introduced detrital sediments from the surface as a result of occasional extreme rainfall events, especially at around 400 ka. The mineralogical data enable an evolutionary model for this flowstone to be generated based on the alternation of flood events with laminar flows and carbonate layers precipitation that can be extrapolated to other caves in which detrital sediments inside speleothems have been found. Copyright © 2014 John Wiley & Sons, Ltd.

The role of microorganisms in the formation of a stalactite in Botovskaya Cave, Siberia – paleoenvironmental implications

Abstract. Calcitic speleothems in caves can form through abiogenic or biogenic processes, or through a combination of both. Many issues conspire to make the assessment of biogenicity difficult, especially when focusing on old speleothem deposits. This study reports on a multiproxy analysis of a Siberian stalactite, combining high-resolution microscopy, isotope geochemistry and microbially enhanced mineral precipitation laboratory experiments. The contact between growth layers in a stalactite exhibits a biogenic isotopic signature; coupled with morphological evidence, this supports a microbial origin of calcite crystals. SIMS δ13C data suggest that microbially mediated speleothem formation occurred repeatedly at short intervals before abiotic precipitation took over. The studied stalactite also contains iron and manganese oxides that have been mediated by microbial activity through extracellular polymeric substance (EPS)-influenced organomineralization processes. The latter reflect paleoenvironmental changes that occurred more than 500 000 yr ago, possibly related to the presence of a peat bog above the cave at that time. Microbial activity can initiate calcite deposition in the aphotic zone of caves before inorganic precipitation of speleothem carbonates. This study highlights the importance of microbially induced fractionation that can result in large negative δ13C excursions. The microscale biogeochemical processes imply that microbial activity has only negligible effects on the bulk δ13C signature in speleothems, which is more strongly affected by CO2 degassing and the host rock signature.

Coarsely crystalline cryogenic cave carbonate – a new archive to estimate the Last Glacial minimum permafrost depth in Central Europe

Abstract. Cryogenic cave carbonate (CCC) represents a specific type of speleothem whose precipitation is triggered by freezing of mineralized karst water. Coarsely crystalline CCC, which formed during slow freezing of water in cave pools, has been reported from 20 Central European caves located in Germany, the Czech Republic, Slovakia and Poland. All these caves are situated in an area which was glacier-free during the Weichselian. Whereas the formation of usual types of speleothems in caves of this region usually ceased during the glacials, coarsely crystalline CCC precipitation was restricted to glacial periods. Since this carbonate type represents a novel, useful paleoclimate proxy, data from its Weichselian occurrences in caves in Central Europe were collected, including their C and O stable isotope values, U-series ages and depth below the surface. When using only the CCC data from caves with limited cave ventilation, the permafrost depths of the Weichselian can be estimated to be at least 65 m in the lowlands and uplands. An isolated CCC find indicates that Weichselian permafrost penetrated to a depth of at least 285 m in the High Tatra mountains, Slovakia. A model of the formation of coarsely crystalline CCC assumes its formation especially during periods of permafrost thawing. U-series data confirm that permafrost depth changed and CCC precipitation in deep caves occurred repeatedly in the studied area during marine isotope stages 4, 3 and 2. One important phase of coarsely crystalline CCC formation related to permafrost thawing occurred between 40 and 21 ka BP, and the last phase of its formation was related to the final permafrost destruction between 17 and 12 ka BP.

Archaeoseismic Evidence of Two Neolithic (7,500-6,000 B.C.) Earthquakes at Tell es-Sultan, Ancient Jericho, Dead Sea Fault

Information on past earthquakes in the Dead Sea basin and the adjacent region was recovered from seismites and faults in lake sediments. Seismites are found in the 70- to 15-ka Lisan formation (Marco et al. , 1996) and in the subsequent Dead Sea deposits (Ken-Tor et al. , 2001; Migowski et al. , 2004; Kagan et al. , 2011). Other sources for palaeoseismic data came from damaged speleothems in caves some 40 km west of the Dead Sea Transform (DST) (Kagan et al. , 2005; Braun et al. , 2009). The present work aims at recovering the earthquake record from the ancient settlement of Jericho (Palestine), renowned as the archaeological site of Tell es-Sultan, inhabited in a period in which we have no local geological information. Tell es-Sultan is suitable for archaeoseismic investigations because (1) it is located in a seismically active area (Fig. 1); (2) it was inhabited continuously during the last 11,000 yr; and (3) the history of the site was repeatedly studied by archaeologists, providing abundant documentation. Starting from the early nineteenth century to the modern expeditions, archaeologists have associated peculiar damaging, fracturing, and human remains discovered at the ancient Jericho site to repeated seismic shaking events during the whole Neolithic history of the site, that is, from approximately 11,000 B.C. up to 6,000 B.C. (Tables 1 and 2). Prof. J. Garstang and Dame K. Kenyon led the two main archaeological teams that considered earthquake effects in this period (Garstang et al. , 1935; Garstang and Garstang, 1948; Kenyon, 1957, 1981). Both renowned for their precious work on the Levant sites, in particular, Dame K. Kenyon was the first to apply the concept of archaeological stratigraphy and to define the still-used chronology for the Levantine Neolithic culture. The analysis in this …

Decoding last interglacial sea-level variations in the western Mediterranean using speleothem encrustations from coastal caves in Mallorca and Sardinia: A field data -- model comparison

U–Th ages of phreatic overgrowths on speleothems in coastal caves of the Western Mediterranean record high sea level positions during marine isotope stage (MIS) 5e of the last interglacial. While relative sea level (RSL) on the southeastern coast of Mallorca stood ∼2.6m above present sea level (apsl) during MIS 5e, it stood ∼4.3m apsl at this time in northwestern Sardinia. The difference between the two sites during MIS 5e and the deviation from the eustatic sea level trend during the Holocene was investigated using the numerical code SELEN. The offset between the eustatic curve and those pertaining to the two sites principally reflect the vertical deformations and geoidal variations in response to meltwater loading. As Sardinia is closer to the center of the Mediterranean basin, the hydro-isostatic component of RSL is enhanced here compared to Mallorca, which results in a modeled offset of ∼60cm between the two sites. This result is qualitatively useful as it provides a partial reconciliation for the site differences. However, the need for refinement in the model is also recognized, as it does not match the observation based on U–Th dating of speleothem overgrowths in Mallorca that sea level there has remained stable for the past 2800 years. Overall, the results of the study first suggest that both sites largely track the eustatic sea level curve, and second suggest that glacial isostatic adjustment is a viable mechanism to reconcile some, if not most, of the relatively small elevation difference of MIS 5e sea level observed at Mallorca and Sardinia, although minor tectonic adjustments cannot be ruled out in explaining some low-amplitude local variations.