Dataciones Th/U de espeleotemas freáticos controlados por el nivel marino, procedentes de cuevas costeras de Mallorca

[cat] Actualment és possible constatar la formació d'espeleotemes freàtics en la superfície dels llacs salobrosos de nombroses coves costaneres de l’illa de Mallorca (Espanya); la seva presència registra amb precisió l’altura mitjana del nivell marí en el moment de la deposició d'aquests carbonats freàtics. Per tant, els dipòsits antics d'espeleotemes freàtics poden ser utilitzats per a reconstruir les fluctuacions de la Mediterrània durant el Pleistocè ja que existeixen, en diverses coves de l’àrea en estudi, abundants alineacions elevades d'aquests espeleotemes que delimiten paleonivells assolits per les aigües freàtiques. S'han datat alguns espeleotemes freàtics, usant el mètode Th/U, amb la intenció de determinar la posició del nivell marí durant el Pleistocè mitjà i superior. Han estat reconegudes tres estabilitzacions altes de la Mediterrània a diferents altures -entre 1,4 i 2,5 metres per damunt de l’actual nivell de fa mar -en coves localitzades en distints sectors de la costa oriental de Mallorca. Les esmentades estabilitzacions es remunten a edats entorn dels 83, 108 i 124 ka B.P. i poden ser relacionades amb diversos events menors dins de l’estadi 5 del registre marí d’isòtops d'oxigen. Així mateix, s'inclouen en aquesta nota algunes dades mineralògiques sobre els espeleotemes datats. Es poden observar diferències d'altura de fins 1 metre en mostres pertanyents al mateix paleonivell marí. Hi són particularment ben documentades les corresponents al subestadi isotòpic 5e, el qual es presenta registrat a altituds majors en les localitats mes septentrionals. Aquestes anomalies altimètriques han de ser explicades en base a una deformació tectònica recent de l’àrea investigada.[eng] Phreatic speleotherns form today at the surface of the brackish pools existing inside littoral caves of Mallorca island (Spain); their occurrence directly identifies the height of the sea level at the time of carbonate deposition. Therefore, ancient phreatic speleothems can be used to reconstruct Mediterranean fluctuations during the Pleistocene, since many raised alignments of these deposits are present in several caves of the studied area. Some phreatic speleothems have been dated using the Th/U method in order to determine the position of the sea level during the Middle and Upper Pleistocene. Three high sea-stands have been recognized at different heights -bemeen 1.4 and 2.5 meters above current sea level- in caves located in various sectors of the eastern coast of Mallorca. They date back to around 83, 108 and 124 ka B P and can be related to several minor events within stage 5 of the marine oxygen isotope record. Some mineralogical data about the analyzed samples are also included in this paper. Differences in height of about 1 meter can be observed in samples corresponding to the same sea paleolevel. Those which are particularly well-documented pertain to substage 5e, with higher elevations towards the northernmost localities. These altimetrical disturbances could be explained in terms of a tectonic tilt of the investigated area

Els espeleotemes freàtics de les coves litorals de Mallorca: canvis del nivell de la Mediterrània i paleoclima en el Pleistocé Superior

Els espeleotemes freàtics de les coves costaneres de Mallorca són una molt bona font d'informació per al millor coneixement de la història recent del nivell de la mar. Diversos paleonivells marins alts --corresponents a esdeveniments interglacials-- es troben enregistrats mitjançant espectaculars alineacions d'espeleotemes freàtics, penjats a diferents altures a coves litorals de Mallorca. De la mateixa manera, alguns episodis regressius de la Mediterrània apareixen també documentats sota la forma de dipòsits d'aquestes característiques situats a cotes inferiors al present nivell de la mar. S'han datat, utilitzant el mètode Th/U, un total de 38 mostres d'espeleotemes freàtics, recol·lectats entre +40 metres per damunt i -23 metres per davall de l'actual nivell marí. Aquestes cristal·litzacions es relacionen amb estabilitzacions positives i negatives de la superficie de les aigües marines, vinculades ales fluctuacions glacio-eustàtiques ocorregudes al llarg del Quaternari. Les edats obtingudes abracen des de 3,9 ka fins a més de 350 ka BP, registrant amb bastant detall una complexa successió de canvis del nivell de la mar durant el Pleistocé Mitja i Superior i l'Holoce. Les estabilitzacions marines altes que apareixen enregistrades corresponen als estadis isotopics càlids 1, 5 i 7; per altra banda, es troben documentades diverses estabilitzacions regressives associades als estadis freds 4, 6 i 8, aixi com alguns abruptes descensos del nivell de la mar intercalats dintre de l'últim interglacial (estadi isotòpic 5). Les dades obtingudes permeten intentar la reconstrucció d 'una corba eustàtica dels últims 300 ka, vàlida per a la Mediterrània Occidental. Aquesta corba resulta especialment detallada entre els 60 ka i els 150 ka BP (estadis isotòpics 4 i 5), posant de manifest l'existència de fluctuacions marines de més de 18 metres d'amplitud ocorregudes en lapses de temps inferiors als 10 ka. Aquest treball representa una contribució novedosa al coneixement de la variabilitat climàtica natural prèvia a les actuals influències antròpiques, resumint-se en ell els resultats principals d'investigacions ja publicades pels autors aixi com algunes noves dades sobre aquestes questions.Phreatic speleothems from coastal caves of Mallorca are a very good source of information for a better knowledge of recent sea-level history. Several high paleosea-levels--corresponding to interglacial events-- are recorded as conspicuous alignments of phreatic speleothems, perched at different heights inside littoral caves of the island. In the same way, some regressive episodes of the Mediterranean Sea also appear documented as deposits of these characteristics located at various depths below present sea-level. Thirty eight samples of phreatic speleothems, collected between +40 metres above and -23 metres below present sea-level, have been dated by means of Th/U method. They record positive and negative sea-level stands related to Quaternary glacio-eustatic fluctuations. Ages obtained range from 3.9 ka to more than 350 ka SP, accurately reflecting a complex succession of shifts in the sea-level occurred during Middle and Upper Pleistocene and Holocene. Recorded high sea-stands clearly correspond to warm isotopic stages 1, 5 and 7; on the other hand, regressive stabilizations associated to cold stages 4, 6 and 8 have been recognized, together with several abrupts sea-lowerings intercalated within isotopic stage 5 (last interglacial). The data obtained allow us to attempt the reconstruction of an eustatic curve for the last 300 ka, valid for the Western Mediterranean basin. This curve shows a remarkable accuracy between 60 ka and 150 ka SP (isotopic stages 4 and 5) and reveals the existence of sea-level fluctuations greater than 18 metres in amplitude within time spans lower than 10 ka. This paper represents a new contribution to the knowledge of natural climatic variability, previous to the current anthropic influences, summarizing the main results of investigations already published by the authors together with some additional data on the subject

Body Shape and Life Style of the Extinct Balearic Dormouse Hypnomys (Rodentia, Gliridae): New Evidence from the Study of Associated Skeletons

Hypnomys is a genus of Gliridae (Rodentia) that occurred in the Balearic Islands until Late Holocene. Recent finding of a complete skeleton of the chronospecies H. morpheus (Late Pleistocene-Early Holocene) and two articulated skeletons of H. cf. onicensis (Late Pliocene) allowed the inference of body size and the calculation of several postcranial indexes. We also performed a Factorial Discriminant Analysis (FDA) in order to evaluate locomotory behaviour and body shape of the taxa. Using allometric models based on skull and tooth measurements, we calculated a body weight between 173 and 284 g for H. morpheus, and direct measurements of articulated skeletons yielded a Head and Body Length (HBL) of 179 mm and a Total Body Length of 295 mm for this species. In addition to the generally higher robustness of postcranial bones already recorded by previous authors, H. morpheus, similar to Canariomys tamarani, another extinct island species, displayed elongated zygopodium bones of the limbs and a wider distal humerus and femur than in an extant related taxon, Eliomys quercinus. Indexes indicated that Hypnomys was more terrestrial and had greater fossorial abilities than E. quercinus. This was also corroborated by a Discriminant Analysis, although no clear additional inference of locomotory abilities could be calculated

Sea level and climate changes during OIS 5e in the Western Mediterranean

Palaeontological, geomorphological and sedimentological data supported by isotopic dating on Oxygen Isotopic Stage (OIS) 5e deposits from the Spanish Mediterranean coast, are interpreted with the aim of reconstructing climatic instability in the Northern Hemisphere. Data point to marked climatic instability during the Last Interglacial (OIS 5e), with a change in meteorological conditions and, consequently, in the sedimentary environment. The oolitic facies generated during the first part of OIS 5e (ca. 135 kyr) shift into reddish conglomeratic facies during the second part (ca. 117 kyr). Sea surface Temperature (SST) and salinity are interpreted mainly on the basis of warm Senegalese fauna, which show chronological and spatial differential distribution throughout the Western Mediterranean. Present hydrological and meteorological conditions are used also as modern analogues to reconstruct climatic variability throughout the Last Interglacial, and this variability is interpreted within the wider framework of the North Atlantic record. All the available data indicate an increase in storminess induced by an increase in the influence of northwesterlies, a slight drop of SST in the northern Western Mediterranean, and an important change in meteorological conditions at the end of OIS 5e (117 kyr). These changes correlate well with the decrease in summer insolation and with the climatic instability recorded in North Atlantic high latitudes

Pleistocene terrace deposition related to tectonically controlled surface uplift: an example of the Kyrenia Range lineament in the northern part of Cyprus

AbstractIn this study, we consider how surface uplift of a narrow mountain range has interacted with glacial-related sea-level cyclicity and climatic change to produce a series of marine and non-marine terrace systems. The terrace deposits of the Kyrenia Range record rapid surface uplift of a long-lived tectonic lineament during the early Pleistocene, followed by continued surface uplift at a reduced rate during mid-late Pleistocene. Six terrace depositional systems are distinguished and correlated along the northern and southern flanks of the range, termed K0 to K5. The oldest and highest (K0 terrace system) is present only within the central part of the range. The K2–K5 terrace systems formed later, at sequentially lower levels away from the range. The earliest stage of surface uplift (K0 terrace system) comprises lacustrine carbonates interbedded with mass-flow facies (early Pleistocene?). The subsequent terrace system (K1) is made up of colluvial conglomerate and aeolian dune facies on both flanks of the range. The later terrace systems (K2 to K5) each begin with a basal marine deposit, interpreted as a marine transgression. Deltaic conglomerates prograded during inferred global interglacial stages. Overlying aeolian dune facies represent marine regressions, probably related to global glacial stages. Each terrace depositional system was uplifted and preserved, followed by subsequent deposits at progressively lower topographic levels. Climatic variation during interglacial–glacial cycles and autocyclic processes also exerted an influence on deposition, particularly on short-period fluvial and aeolian deposition

Late Quaternary sea-level change and early human societies in the central and eastern Mediterranean Basin : an interdisciplinary review

This article reviews key data and debates focused on relative sea-level changes since the Last Interglacial (approximately the last 132,000 years) in the Mediterranean Basin, and their implications for past human populations. Geological and geomorphological landscape studies are critical to archaeology. Coastal regions provide a wide range of resources to the populations that inhabit them. Coastal landscapes are increasingly the focus of scholarly discussions from the earliest exploitation of littoral resources and early hominin cognition, to the inundation of the earliest permanently settled fishing villages and eventually, formative centres of urbanisation. In the Mediterranean, these would become hubs of maritime transportation that gave rise to the roots of modern seaborne trade. As such, this article represents an original review of both the geo-scientific and archaeological data that specifically relate to sea-level changes and resulting impacts on both physical and cultural landscapes from the Palaeolithic until the emergence of the Classical periods. Our review highlights that the interdisciplinary links between coastal archaeology, geomorphology and sea-level changes are important to explain environmental impacts on coastal human societies and human migration. We review geological indicators of sea level and outline how archaeological features are commonly used as proxies for measuring past sea levels, both gradual changes and catastrophic events. We argue that coastal archaeologists should, as a part of their analyses, incorporate important sea-level concepts, such as indicative meaning. The interpretation of the indicative meaning of Roman fishtanks, for example, plays a critical role in reconstructions of late Holocene Mediterranean sea levels. We identify avenues for future work, which include the consideration of glacial isostatic adjustment (GIA) in addition to coastal tectonics to explain vertical movements of coastlines, more research on Palaeolithic island colonisation, broadening of Palaeolithic studies to include materials from the entire coastal landscape and not just coastal resources, a focus on rescue of archaeological sites under threat by coastal change, and expansion of underwater archaeological explorations in combination with submarine geomorphology. This article presents a collaborative synthesis of data, some of which have been collected and analysed by the authors, as the MEDFLOOD (MEDiterranean sea-level change and projection for future FLOODing) community, and highlights key sites, data, concepts and ongoing debates

Oxygen isotope geochemistry of the Granite Harbour Intrusives, Wilson Terrane, Northern Victoria Land, Antarctica

The oxygen and strontium isotope compositions of the Cambro-Ordovician granitoids cropping out in the Wilson Terrane (Granite Harbour Intrusives-GHI) constrain the petrological evolution of the magmatism in Antarctica, related to the Ross Orogeny. The measured delta(18)O(WR) values of these intrusives define three different compositional groups: the metaluminous rocks (MAG), with delta(18)O(WR) ranging from 6.9 (olivine gabbro) to 11.4parts per thousand (monzogranite); the unaltered peraluminous granites (PAG), having delta(18)O(WR) values ranging from 10.6 to 13.2parts per thousand, and the foliated peraluminous leucogranites (SKG), characterised by delta(18)O(WR) values above 14parts per thousand. The analysis of equilibrium mineral assemblages indicates that the high delta(18)O(WR) values are magmatic and unaffected by low-temperature processes. A few peraluminous granites sampled in the vicinity of Cenozoic intrusions show anomalously low delta(18)O(WR), due to meteoric-hydrothermal alteration. The isotopic data indicate that the coeval and spatially related metaluminous mafic and felsic intrusives forming the GHI were not comagmatic: the mafic and intermediate rocks were likely derived from lower crustal contamination of a pristine basaltic magma; their delta(18)O(WR) values were also increased during emplacement, due to the interaction with the adjacent O-18-rich hydrous felsic magmas (mixing). Oxygen isotope data indicate that the crustal sources producing the Granite Harbour intrusives were not homogeneous: the felsic metaluminous intrusives were produced by partial melting of fertile rock with possible igneous origin, whereas partial melting of a metapelitic source rock is claimed for the genesis of the peraluminous granites

Phreatic overgrowths on speleothems: a useful tool in stuctural geology in littoral landscapes. The example of Eastern Mallorca (Balearic Islands)

Along the eastern coast of Mallorca, many littoral caves partly filled with brackish waters occur. The most peculiar aspect of these caves is the presence of abundant phreatic overgrowths formed on pre-existing supports located at the underground pools’ water table, which corresponds to the present sea level. Besides a specific geomorphological interest, these subaqueous speleothems provide an excellent record of Quaternary sea level stands. The clear relation between phreatic speleothem growth and the contemporary sea level allows the control of the tectonic evolution of an area, by comparing speleothems’ ages and heights with the regionally established eustatic curves. In the studied region different altimetric positions of coeval phreatic speleothems suggest the existence of a recent tectonic activity. The characteristics and chronology of this tectonic event are the objectives of this paper, pointing out at the same time the potential of phreatic speleothems in structural geology investigations. Along the coastline of the studied area, alignments of phreatic speleothems attributed to high sea stands 5a, 5c and 5e are recorded at increasing elevations northwards. This is an evidence of a significant tectonic tilting that took place, at least partially, after substage 5a because phreatic speleothems of this substage are now located at different altitudes. Considering that tectonic tilting has been continuous from post-substage 5a (approximately 85 ka) until now, and that normal displacement is approximately of 1.5 m, the average minimum velocity of the tilting can be estimated about 0.02 mm/year in the southern part with respect to the north end. Data obtained from phreatic speleothems have been compared with other regional, stratigraphical, geomorphological and tectonic evidence that all together point to the same existence of the postulated tectonic tilting. Consequently, phreatic speleothem investigation results in a new method that allows the quantification of average velocities of tilting as well as other tectonic movements with high precision. This methodology can be extended to any littoral karstic landscape where phreatic speleothems are present