changing perspectives in the concept of lago mare in mediterranean late miocene evolution abstract the cenozoic alpine orogeny caused the partition of tethys into several basins during the late neogene the mediterranean attained its final configuration whereas eastwards the paratethys isolated from the world ocean disintegrated progressively into a series of smaller basins as a result an endemic fauna developed in these basins mainly composed of brackish to freshwater faunas indicating an environment affected by changes in water salinity these small basins of the paratethys were named sea lakes by andrusov andrusov d 1890 les dreissenidae fossiles et actuelles d eurasie geol min 25 1 683 in russian subsequently this name was translated into lac mer gignoux m 1936 geologie stratigraphique 2 edition masson paris in the mediterranean isolated from the atlantic at the end of the miocene messinian thick evaporites deposited consisting of a marine lower evaporite unit and an upper evaporite unit mainly of continental origin ruggieri ruggieri g 1962 la serie marine pliocenica e quaternaria della val marecchia atti acad sci lett arti palermo 19 1 169 used the term lago mare to characterize the brackish to fresh water environment which occurred within the mediterranean at the end of the messinian during recent decades numerous scientific investigations concerning the history of the messinian within the mediterranean were devoted to the understanding of conditions prevailing after the deposition of the marine evaporites brackish to freshwater faunas are found in several outcrops and boreholes in the mediterranean both in the uppermost beds of gypsum and inter bedded within the clastic sediments of the upper evaporite unit immediately preceeding the flooding by the marine pliocene waters these faunas because of their similarities with the fauna described in the paratethys were named paratethyan or caspi brackish fauna this leading some authors to imply a migration of these fauna from paratethys to the mediterranean however others refute this hypothesis new data induced some researchers to consider that exchanges existed between the mediterranean and the eastern paratethys and also between the mediterranean and the atlantic ocean at the miocene pliocene transition these investigations now take advantage of the accurate time scales established by authors biostratigraphy cyclostratigraphy magnetostratigraphy allowing good stratigraphic correlations between the mediterranean and the paratethys and precisions on the geodynamic evolution of this area furthermore sediments at the base of the zanclean mpl1 locally containing brackish to fresh water faunas conducted authors to attribute this formation to an infra or pre pliocene and also to a lago mare event thus the lago mare concept drifted from its original meaning and is evolving because of progresses in the understanding of the mediterranean geodynamics and the adjacent areas during the miocene pliocene transition

tectonics and sequence stratigraphy in messinian basins sicily constraints on the initiation and termination of the mediterranean salinity crisis deposits within the caltanissetta basin of central sicily have been important for developing the desiccating deep basin model for the messinian salinity crisis in the mediterranean linked structural and stratigraphic studies show that the sicilian depocenters are synclines related to underlying thrust structures of the frontal part of the maghrebian chain prior to the salinity crisis these basins were hydrodynamically linked through the foredeep to the mediterranean the precursor sediments terravecchia formation formed a delta sourced from the north early messinian regression acted on a range of paleobathymetries shallow in the north and progressively deeper in the south locally complicated by active thrust structures initial draw down of mediterranean base level is marked across the thrust belt by first cycle carbonates and evaporites on the structural highs and lows respectively vast accumulations of halite and potassium salts up to 1200 m are restricted to growing thrust synclines the different evaporite signatures may be related to different water conditions reflecting various meteoric and marine circulations across various subbasins with cyclicity reflecting high frequency variations in sea level a sequence stratigraphic model is developed to explain fractionation of evaporite facies between different paleobathymetric settings and to predict the temporal evolution of the successions in different subbasins thrusting provides accommodation space for evaporites and also controls the water pathways into the desiccating basins the intra messinian unconformity separating first and second cycle evaporites is a type 1 sequence boundary related to the forced regression associated with the acme of mediterranean desiccation an interpretation supported by local ravinement and incised valley fills the overlying second cycle evaporites are a combination of detrital reworked first cycle material and primary gypsum formed under brackish water regional onlap relationships and bed continuity suggest that this water body was of regional extent with a systematically rising base level these interpretations have several implications for messinian correlations in the mediterranean the deep basin evaporites correlate with an intra messinian unconformity that separates the two cycles on sicily and postdate the first cycle deposits regional base level was largely restored before the end of the salinity crisis

a stable isotope study of serpentinization and metamorphism in the highland border suite scotland u k abstract d h and 18 o 16 o ratios have been measured for whole rock samples and mineral separates from the mafic and ultramatic rocks of the cambro ordovician highland border suite the h and o isotopic compositions of these rocks record individual stages in a relatively complex 500 myr old hydrothermal metamorphic history lizardite serpentinites d 105 18 o 6 2 record a premetamorphic history and indicate that parent harzburgites dunites and pyroxenites were serpentinized through low temperature interaction with meteoric waters during cooling the other rocks of the highland border suite record subsequent interaction with metamorphic fluids amphibolite facies hornblende schists were produced through thrust related dynamothermal metamorphism of spilitic pillow lavas during dehydration d enriched fluids were driven off from the spilites thus leaving the hornblende schists to equilibrate with a relatively d depleted internal fluid reservoir d 45 the expelled d enriched fluids may have mixed with more typical dalradian metamorphic waters which then exchanged with the remaining mafic rocks and lizardite serpentinites during greenschist facies regional metamorphism to produce antigorite serpentinites d 62 18 o 8 and greenschist metaspilites d 57 18 o 7 3 with similar h and o isotopic compositions serpentinites which have been only partially metamorphosed show intermediate h isotopic compositions between that of metamorphic antigorite d 62 and non metamorphic lizardite d 105 end members

from foreland to forearc domains new multichannel seismic reflection survey of the mediterranean ridge accretionary complex eastern mediterranean abstract the mediterranean ridge of the eastern mediterranean sea is a huge accretionary wedge emplaced as a consequence of the africa aegean plate convergence that has a rate estimated at 40 mm yr processing of recent multichannel seismic data and integration with previous results seismic profiling swath bathymetry sonar have facilitated the study of the overall deformation pattern of the area which includes three distinct major structural domains facing various forelands 1 1 the outer domain is bounded southward by the present day wedge toe and towards the north by topographic slope breaks and clear changes in deformational style beneath the ionian and levantine mediterranean ridge branches the base of messinian evaporites seems to act as a major decollement level 2 2 the central or crestal domain the shallowest one shows evidence of mud diapiric and mud volcano activity and is overthrusting northward over the inner domain facing the libyan margin this area which displays spectacular mud volcano fields appears much wider and shallower 3 3 the less deformed inner domain is bounded northward by the hellenic trench system beneath its ionian inner area seismic velocities characteristic of continental crust have been recorded while within its levantine region it is made of a series of disconnected and uplifted basement blocks strabo seamounts along the matapan and pliny trenches structures which could be caused by transpressive deformation are locally observed we believe that both the north south structural arrangement and the clear west east lateral variations of the mediterranean ridge relate to its progressive collision against the libyan margin promontory this event which may have initiated 5 6 myr ago may have induced a a differentiated paleogeography of messinian evaporites later available for tectonic accretion leading to the further lateral structural variations of the outer domain and b strain partitioning between the central mediterranean ridge and the hellenic trench system

messinian crisis what happened around the northeastern aegean abstract the effects of the severing of the atlantic mediterranean connection during the 400 000 year messinian event are also observed around the northern aegean during this time a sea of brackish water character developed between paratethys in the north and the mediterranean in the south this sea is named here egemar this basin was principally fed by surrounding rivers and by paratethyan waters that entered egemar via a connection through the sea of marmara which was then a bay of the paratethys the sedimentary sequence deposited in egemar is principally composed of limestones containing brackish water fauna paratethyan however there are some intercalations containing mediterranean species five intercalations of mediterranean character are found within the sedimentary sequence of egemar indicating the re establishment of an atlantic mediterranean connection from time to time and thus replenishment of marine waters the turolian is represented by continental clastics which interdigitate with the brackish water cycles implying a number of regressions egemar eventually became part of the eastern mediterranean due to a major transgression during the early pliocene

paratethyan mediterranean connectivity in the sea of marmara region nw turkey during the messinian the sea of marmara region is thought to have been a gateway between paratethys and the mediterranean since the middle miocene and is therefore an important control on water mass exchange between the two realms the miocene successions in the northeastern aegean and northwestern marmara regions indicate that the first mediterranean marine transgression to affect these areas occurred during the late serravallian in the northeastern aegean region frequent marine incursions occurred during the tortonian and messinian stages the messinian stage in this area is represented by a package of brackish to fresh water carbonates with some marine sandstone siltstone interbeds alcitepe formation which conformably overlies the tortonian kirazli formation the messinian sequence is overlain with an erosional contact by a shallow marine siliciclastic sequence goztepe formation of zanclean age with its brackish to fresh water carbonates and broadly constrained age the messinian sequence is interpreted as being coeval with the upper evaporite lago mare sequence observed in western mediterranean basins in the western marmara region the pontian messinian alcitepe formation consists of bioclastic and oolitic limestones with basal clastic rocks it conformably overlies the fluvio lacustrine siliciclastic sediments of the middle to upper miocene kirazli formation and is overlain by fluvio lacustrine sediments of the kimmerian 5 5 3 2 ma truva and tevfikiye formations with an erosional contact the bioclastic limestones of the alcitepe formation in the western marmara region contain a molluscan and ostracod fauna that are endemic to paratethys these fauna indicate deposition in a shallow brackish to fresh water environment faunal and paleomagnetic analyses of a section of the alcitepe formation at yenimahalle canakkale confirm that the formation is of pontian age and represents chron c3r 6 04 5 24 ma the ostracod analysis indicates that during deposition of the alcitepe formation salinity increased from brackish in the lower part to more saline conditions in the upper part ostracod valves have low 87sr 86sr values relative to coeval late miocene ocean water this indicates that exchange between the sea of marmara region and the global ocean was restricted throughout this period fossil and sr isotope evidence suggests however that there was a paratethyan marmara connection during the deposition of the lower part of the alcitepe formation with paratethyan influence reaching the north aegean connection via marmara between paratethys and the mediterranean was not re established until the late aktchagylian late pliocene the re connection was caused by both increased activity on the north anatolian fault and global sea level rise

fossils and tectonics along the highland boundary fault in scotland the tectonic significance of fossil discoveries from the highland border complex of scotland is described these sparse but diverse macro and microfossils have been recovered from a wide range of lithologies across scotland and range in age from early to late ordovician thereby refuting any attempt to incorporate the hbc within the dalradian supergroup the lower cambrian trilobite fauna from the leny limestone could represent an isolated remnant of an early development of the ordovician hbc basin s or alternatively may provide an upper age limit for dalradian sedimentation further palaeontological prospecting in the zone especially in relatively undeformed late dalradian sediments could resolve this and other problems which complicate the regional tectonic interpretations

origin of exotic clasts in the central southern apennines clues to the cenozoic fold and thrust collisional belt in the central mediterranean area

discovery of vast fluvial deposits provides evidence for drawdown during the late miocene messinian salinity crisis the late miocene messinian salinity crisis msc was a significant oceanographic event that caused widespread evaporitic accumulation throughout the mediterranean basin although multiple hypotheses exist regarding the origin of evaporitic and post evaporitic deposits researchers remain divided on the magnitude of base level fall and on whether these accumulations record deep water or non marine conditions here we introduce a previously unknown upper messinian fluvial deposit comparable in size to the late miocene nile river fluvial valley fill and show that near complete desiccation of the eastern mediterranean was responsible for its development the basin wide accumulation which is located offshore cyprus syria lebanon and israel lies directly atop deep basin evaporites and related erosional surfaces and is one of the largest known riverine deposits associated with the terminal msc from marked onshore incision and basinward thinning trends the source of the accumulation is presumed to be a formerly unidentified drainage basin in southern turkey and western syria the deposit extends 500 km into the western levant basin where its depositional sink is marked by six well developed backstepping lobes based on the deposit s seismic stratigraphy and morphology which provide clear evidence of subaerial exposure we question current hypotheses proposing a deepwater origin for late messinian accumulations we also draw specific attention to the development of extensive circum mediterranean nonmarine conditions prior to zanclean marine transgression and to the previously overlooked role of fluvial systems in diluting hypersaline lakes in evaporitic basins

sedimentary features influencing the occurrence and spatial variability of seismites late messinian gargano promontory southern italy abstract seventeen layers characterized by soft sediment deformation structures ssds were identified within the calcari di fiumicello an upper messinian miocene stratigraphic unit 30 m thick cropping out in the northern sector of the gargano promontory apulia southern italy facies analysis was performed on the whole outcrop and detailed sedimentological investigations were carried out on the deformed beds in order to interpret the deformation mechanism the driving mechanism and the possible trigger agent deformed layers occur in some thin bedded ooidal limestones skeletal calcarenite as well as in some pebble size conglomerate alternated with marls deposited in a protected embayment or barrier island lagoon system possibly characterized by high salinity and tidal influx ssds can be classified as load and slump slide structures the continuous exposures allow us to follow a single deformed layer along tens of meters hence several types of lateral variations were observed that can be summarised as follows 1 ssds disappear within a few meters with a decreasing pattern of their deformation or in an abrupt way 2 deformed layers laterally change in thickness and morphology and 3 a single deformed bed can laterally correspond to two deformed beds most of the soft sediment deformation features were identified as liquefaction and or fluidization features related to seismic shocks seismites seismites are often used as an indicator of seismic events especially along small outcrops trench excavation and core analysis this study highlights the value of the sedimentological analysis for paleoseismic investigations with the aim of improving criteria for identifying seismites in the sedimentary record and their suitability as marker of seismic events

thrust top lacustrine lagoonal basin development in accretionary wedges late messinian lago mare episode in the central apennines italy abstract we analysed in detail the geometry sedimentology and palaeontology both mollusc and ostracod assemblages of a small lacustrine lagoonal basin located at about 1100 m a s l in the marsica region of the apennines at le vicenne locality l aquila abruzzo central italy the structure of the basin infill deposits outlines an open syncline with an e w axis polygenic conglomerates interbedded with clay levels and sandy marls which constitute roughly coarsening upward progradational sequences are the dominant lithologies these sequences are interpreted as lacustrine to coastal lagoon deposits with episodic fan delta supplies this sedimentological interpretation is also supported by mollusc and ostracod assemblages which suggest that the sedimentary environment was characterized by a mesohaline closed water body with salinity probably ranging from 10 to 13 both mollusc and ostracod assemblages show a clear paratethyan influence in the ostracod assemblage ten species out of the fourteen collected forms belong to the loxoconcha djaffarovi zone as defined by carbonnel 1978 thus it is possible to refer the siltitic clayey intercalations of le vicenne to the top of the messinian post salinity crisis the presence of a strong angular unconformity at the base of the basin together with the structural setting of its deposits suggesting a light compressive deformation are common features in all the thrust top basins recognized in the central apennines taking into account the regional data the age of the youngest deposit involved in the substratum siliciclastic turbidites which recorded the messinian salinity crisis and the palaeobiological indications given by the mollusc and ostracod assemblages it is possible to constrain the origin of the le vicenne basin to the messinian lago mare early pliocene tectono sedimentary event of the apennines the recognition in the marsica range of this thrust top basin allows us to attempt a palinspastic reconstruction locating the marsica region in the latest miocene early pliocene active thrust zone of the apennine accretionary wedge

towards an astrochronological framework for the eastern paratethys mio pliocene sedimentary sequences of the focsani basin romania abstract a reliable geological timescale for the neogene sedimentary deposits of the romanian carpathian foredeep did not exist so far due to the lack of accurate isotopic datings and straightforward magnetostratigraphic correlations here we present a new chronology for the upper miocene to pliocene deposits of the westernmost part of the eastern paratethys based on high resolution magnetostratigraphic data from the focsani basin the thick and continuous river sections of putna 2 35 km and rimnicu s rat 7 32 km yield excellent magnetostratigraphic results and allow an unambiguous correlation to the polarity timescale for the interval between 7 and 2 5 ma the new age control permits the calculation of accumulation rates for each polarity zone which shows a significant increase at approximately 5 8 6 my the upper miocene to pliocene sedimentary rocks of the focsani basin display cyclic alternations of sandy units and finer intervals the calculated values for the average duration of the observed sedimentary cycles are very close to the average duration of precession 21 7 ky which indicates that the sedimentary cycles from the eastern carpathian foredeep deposits are astronomically forced we show that the usage of the unambiguous time control offered by magnetic polarity stratigraphy would give a more realistic picture of the processes that have taken place in this tectonically active region

decoding the mediterranean salinity crisis this historical narrative traces the steps to unravel over a span of 40 years an extraordinary event in which 5 of the dissolved salt of the oceans of the world was extracted in a fraction of a million years to form a deposit more than 1 million km 3 in volume a buried abyssal salt layer was identified with reflection profiling and sampled during the deep sea drilling project leg 13 the dolomite gypsum anhydrite and halite in the drill cores paint a surprising picture of a mediterranean desert lying more than 3 km below the atlantic ocean with brine pools that shrank and expanded by the evaporative power of the sun the desert drowned suddenly when the gibraltar barrier gave way the explanation of deep basin shallow water desiccation and the notion of a catastrophic zanclean flood had a mixed reception however the hypothesis became broadly accepted following subsequent drilling expeditions nevertheless as experts examined the evaporate facies and sequences of equivalent age in the terrestrial outcrops weaknesses appeared in the concept of repeated flooding and drying to account for the magnitude of the deposits the rosetta stone used to decipher conflicting interpretations turns out not to be the deposits but the erosion surfaces that enclose them these surfaces and their detritus formed in response to the drop in base level during evaporative drawdown extend to the basin floor evaporative drawdown began halfway through the salinity crisis when influx from the atlantic no longer kept up with evaporation prior to that time a million years passed as a sea of brine concentrated towards halite precipitation during the later part of this interval more than 14 cyclic beds of gypsum accumulated along shallow margins modulated by orbital forcing the thick salt on the deep seabed precipitated in just the next few cycles when drawdown commenced and the brine volume shrank upon closure of the atlantic spillway the remnants of the briny sea transformed into salt pans and endorheic lakes fed from watersheds of eurasia and africa the revised model of evaporative concentration now has shallow margin shallow water and deep basin deep water precursors to desiccation

mediterranean messinian salinity crisis constraints from a coeval marginal basin sorbas southeastern spain abstract the extent timing and effects of late miocene desiccation and evaporite deposition in the mediterranean sea remain controversial marginal basins containing messinian 5 3 7 1 ma sequences now exposed onland supplement information from the deep mediterranean but have evaporites of a variety of ages some of these messinian evaporites pre date and others post date deep desiccation none appears to be exactly coeval with those of the deep mediterranean in the betic cordillera of southern spain basins e g granada basin far from the present day mediterranean lost connection with the mediterranean due to uplift 1 ma before the salinity crisis and have marine evaporites of early not late messinian age in contrast basins such as the sorbas basin in southeastern spain adjacent to the present day mediterranean record events directly reflecting the course of the salinity crisis the sorbas basin retained marine connection with the western mediterranean up until evaporative drawdown in the mid messinian and was rapidly reflooded immediately afterwards the sorbas messinian sequence is up to 320 m thick it is complete and normal marine except for an incised basinwide erosion surface overlain by a 130 m thick gypsum deposit we propose that this surface marks the interval of deep desiccation of the adjacent mediterranean basin erosion occurred shortly after 5 9 ma and the irregular unconformity has relief of at least 240 m confirming mediterranean drawdown significantly below the atlantic level sorbas gypsum deposits overlie the unconformity and are intercalated with marls estimated at 5 5 ma containing normal marine messinian biotas these gypsum deposits therefore post date deep desiccation and formed in a silled basin immediately following marine reflooding they mark the end of the salinity crisis and are overlain by 70 m of normal marine sediments containing unreworked foraminifers of latest messinian age this succession demonstrates that the salinity crisis occurred faster and was completed sooner than previously believed it took place within 0 4 ma time scale of berggren et al 1995b is 0 2 ma on the time scale of baksi 1993 and was completed before the end of the messinian this corrects previous views that the salinity crisis continued until the early pliocene there is no evidence in the sorbas basin for brackish lago mare conditions and the normal marine biotas that directly precede and follow drawdown rebut earlier suggestions of prolonged salinity effects

reconstruction of the paleoenvironmental changes around the miocene pliocene boundary along a west east transect across the mediterranean abstract in order to reconstruct the environmental changes at the end of the messinian salinity crisis a multidisciplinary study has been carried out with a high sampling resolution of the late messinian early zanclean zone mpl 1 sediments along a west east mediterranean transect the studied examples comprise sections from southern spain vera almanzora balearic basin odp site 975 tyrrhenian basin odp site 974 sicily eraclea minoa zakynthos kalamaki corfu aghios stefanos crete aghios vlasis previously analyzed sections from the levantine basin cyprus and odp sites 968 and 969 are used for comparison the sections have been correlated using planktonic foraminiferal assemblages sedimentological and stable isotope variations and compared to the astronomical cyclicity defined in the miocene pliocene boundary stratotype of eraclea minoa sicily variations of caco3 content stable isotopes of carbonates 18o 13c and foraminiferal assemblages indicate similar environmental transition at the miocene pliocene boundary in all of the investigated sections the latest messinian deposits are barren of fossils or characterized by only reworked planktonic foraminifers except for the sporadic presence of ammonia tepida brackish or lacustrine ostracods and brackish mollusks typical of the lago mare facies the oxygen and carbon isotopic compositions of carbonates usually exhibit large variations with dominantly low values indicating freshwater dilution the earliest pliocene mpl 1 cycle 1 shows a rapid and progressive increase of the 18o values which indicates the restoration of marine conditions after the lago mare event normal marine environments were definitely established and stabilized at the top of cycle 1 these data confirm that the inflow of marine waters occurred contemporaneously within the whole mediterranean at the base of pliocene although stable marine conditions occurred only about 20 kyrs later

astrochronology for the messinian sorbas basin se spain and orbital precessional forcing for evaporite cyclicity the sorbas basin of se spain contains one of the most complete sedimentary successions of the mediterranean reflecting the increasing salinity during the messinian salinity crisis a detailed cyclostratigraphic study of these successions allows a correlation of the sedimentary cycle patterns to astronomical target curves here we present an astrochronological framework for the messinian of the central part of the sorbas basin this framework will form a solid basis for high resolution correlations to the marginal carbonate facies and to the central mediterranean area the early messinian abad member contains 55 precession induced sedimentary cycles marked by homogeneous marl opalrich bed alternations in the lower abad and by homogeneous marl sapropel alternations in the upper abad astronomical tuning results in an age of 5 96 ma for the transition to the yesares evaporites and thus for the onset of the messinian salinity crisis the marl sapropel cycles of the upper abad are replaced by gypsum sapropel cycles 14 in the yesares member indicating that the evaporite cyclicity is related to precession controlled oscillations in circum mediterranean climate as well as a consequence gypsum beds correspond to precession maxima insolation minima and relatively dry climate sapropelitic marls to precession minima insolation maxima and relatively wet climate an alternative glacio eustatic obliquity control for evaporite cyclicity can be excluded because the number of sedimentary cycles with a reversed polarity is too high sedimentation during the abad yesares and the overlying coastal sequences of the sorbas member took place in a continuously marine environment indicating that marine conditions in the sorbas basin prevailed at least until 5 60 5 54 ma according to our scenario deposition of the yesares and sorbas member took place synchronously with deposition of the lower evaporites in the central mediterranean finally the continental zorreras member consists of 8 sedimentary cycles of alternating reddish silts dry climate and yellowish sands wet climate which correlates very well with the upper evaporites and lago mare facies of the mediterranean q 2001 elsevier science b v all rights reserved

cambrian and late precambrian basaltic igneous activity in the scottish dalradian a review in the evolution of the scottish dalradian basin the climax of widespread tholeiitic magmatism pre dated or coincided with major basement faulting and the onset of deep marine sedimentation in lower cambrian times earlier basin deepening and precursory igneous activity had already occurred major and trace element chemistry of low grade metabasites indicates their affinity with basalts from ocean spreading centres or transition to within plate types geological evidence favours a tectonic setting for this igneous suite and the highland border series on the nw margin of an actively evolving lower cambrian ocean basin possibly a marginal basin to the iapetus ocean system

calcareous nannofossil biostratigraphy and magnetostratigraphy of the upper miocene and lower pliocene of the northern aegean orphanic gulf strimon basin areas greece abstract the transitional position of the northern aegean makes it an important area for studying the relation between the mediterranean and the eastern paratethys a chronostratigraphic framework has been obtained for the late neogene deposits along the orphanic gulf and in the strimon basin of northern greece by analysing calcareous nannofossil data and paleomagnetic results from eight sections the local formations and major lithological units have been correlated with the upper miocene and lower pliocene stages furthermore the obtained framework has facilitated a more detailed reconstruction of the effects of the messinian salinity crisis on the sedimentary record magnetostratigraphic data from the strimon basin result in an age estimate of 6 3 ma for the dafni choumnikon formation transition between normal polarity subchrons c3an 2n and c3an 1n since this late miocene age estimate corresponds closely to estimates of the maeotian pontian boundary in the eastern paratethys dacic basin we believe this transition from marine to brackish conditions corresponds to this latter boundary the gypsiferous unit in the basal part of the choumnikon equivalent beds along the orphanic gulf can then be correlated with the evaporites in the northern aegean and the lower evaporites of the mediterranean basin consequently we assume that these northern aegean evaporites have been deposited between 5 96 and 5 59 ma freshwater deposits above the evaporites are easily traceable across the orphanic gulf area as a gravel or sandstone unit topped by a travertine marker bed and have a wide lateral continuation since their position is intermediate between the shallow marine gypsum anhydrite and the more open marine clastics of the pliocene we argue that these beds correlate with the desiccation phase of the mediterranean and black sea basins this intra messinian event probably occurred between 5 59 and 5 50 ma thus predating the upper evaporites or lago mare of the mediterranean a clear recognition of the miocene pliocene boundary remains problematic in the orphanic gulf area nannofossil assemblages in the sections suggest a higher position of the local base of the pliocene than indicated by the level with the first appearance of planktonic and benthic foraminifera discontinuous occurrences of levels containing nannofossil assemblages of zone mnn11b c are found between the travertine unit and the lowermost pliocene beds representing brief marine ingressions the latter show that in the latest messinian presumably temporary connections of atlantic mediterranean waters with the northern aegean basin existed these marine ingressions likely extended further into the eastern paratethys as demonstrated by the presence of nannofossil assemblages in the middle and upper pontian of the dacic and euxinic basins the events around the miocene pliocene transition resulted in a fairly abrupt change from brackish to open marine conditions in a relative deep basin which was subject to increased rates of subsidence from the onset of evaporite deposition in the late messinian onward

tectonic history of the ophiolitic rocks of the highland border fracture zone scotland stable isotope evidence from rock fluid interactions during obduction abstract the mafic and ultramafic rocks of the highland border fracture zone are ophiolitic remnants of a pre grampian marginal basin that opened either within or to the north of the dalradian sedimentary pile closure of the basin was achieved through a combination of northerly directed subduction and obduction of ophiolitic thrust slices onto the basin s southern margin during the early stages of obduction young hot peridotite slabs were thrust over the cold upper surfaces of lower thrust sheets producing a dynamothermal metamorphic sole serpentinisation of these peridotites whilst they were still cooling occurred in a near surface position through the interaction of meteoric waters subsequently the ophiolitic thrust sheets which comprise lizardite serpentinites spilitic pillow lavas and aureole rocks were thrust over the uppermost dalradian nappes which were themselves being expelled southwards thereby accommodating basement shortening grampian regional metamorphism of the nappe pile and overlying highland border suite ophiolitic thrust sheets produced greenschist metaspilites from the spilitic pillow lavas induced minor retrogression in the aureole rocks and caused the lizardite in the serpentinites to be recrystallised and replaced by antigorite the highland border suite greenschist facies metamorphic fluids were d enriched compared with low grade dalradian metamorphic waters and may have been mixtures of the latter and d rich dehydration fluids released from the mafic rocks during dynamothermal metamorphism brittle fracturing and shearing in the serpentinites were responses to late deformation at different crustal levels during the final stages of emplacement which involved gravity sliding as well as downbending of the dalradian nappes and ophiolitic thrust sheets against the elevated midland valley block

late miocene events in the mediterranean as recorded by carbonate evaporice relations the messinian stage in the mediterranean region is known mainly because of a major evaporitic event whose causes and global implications are still under discussion correlations between basinal evaporite bearing series and marginal carbonate platforms allow for improvement of the classical depostional models especially concerning the eustatic control of the environmental changes in the mediterranean these changes were controlled by the interplay of aperiodic and periodic factors 1 tectonics related to the relative motions of the african and eurasian plates and resultant linear increase in the basin restriction 2 sea level fluctuations that alternately aggravated the restriction or allowed marine replenishment and 3 climatic fluctuations that controlled the level of the mediterranean during stages of isolation the messinian sedimentary succession reflects a typical sequence of progressive isolation marine marls yields laminites yields transitional deposits yields evaporites yields lacustrine deposits the first stage of the so called salinity crisis was characterized by a mediterranean lowstand that resulted in erosion of former platforms and deposition of the lower evaporites during the next stage sea level rose tb3 3 cycle high enough to temporarily replenish the basin cyclic upper evaporites with development of stromatolite rich deposits finally the uppermost messinian freshwater to brackish lacustrine deposits reflect both themore cessation of sea water input maximum tectonic isolation low sea level and freshwater input related to increasing runoff less

sedimentological and paleoenvironmental scenario before during and after the messinian salinity crisis the san miguel de salinas composite section western mediterranean abstract a composite stratigraphic section ranging from the messinian to the pliocene recording the most important phases of the messinian salinity crisis is represented in the san miguel de salinas area bajo segura basin se spain detailed magnetostratigraphic and facies analyses and foraminifer and nannoplankton assemblage studies were carried out integration of the results has allowed the characterization of the pre evaporitic synthem messinian i syn evaporitic synthem messinian ii and post evaporitic phases synthem pliocene from a paleoenvironmental and chronostratigraphic standpoint the pre evaporitic phase is late messinian and records a shallowing upward trend the syn evaporitic phase took place in chron c3r and is characterized by laminated marls with intercalated selenitic gypsum beds and sandstones variations in foraminifer and nannoplankton assemblages together with episodic gypsum precipitation record major changes in water salinity in a stressed marine environment the pre and syn evaporitic phases are separated by the intra messinian unconformity represented by an erosional surface related with a sea level fall after the evaporitic phase a sea level fall generates the end messinian unconformity whose strongly erosional nature is evidenced by the deeply carved paleovalley of san miguel de salinas the post evaporitic phase begins in the earliest pliocene and records the re establishment of normal marine conditions in the basin since the san miguel de salinas composite section can be considered as a benchmark for the study of the evolution of marginal mediterranean basins during the messinian salinity crisis the detailed characterization of these different phases is of great importance in understanding this event

chronology causes and progression of the messinian salinity crisis the messinian salinity crisis is widely regarded as one of the most dramatic episodes of oceanic change of the past 20 or so million years 1 3 earliest explanations were that extremely thick evaporites were deposited in a deep and desiccated mediterranean basin that had been repeatedly isolated from the atlantic ocean1 2 but elucidation of the causes of the isolation whether driven largely by glacio eustatic or tectonic processes have been hampered by the absence of an accurate time frame here we present an astronomically calibrated chronology for the mediterranean messinian age based on an integrated high resolution stratigraphy and tuning of sedimentary cycle patterns to variations in the earth s orbital parameters we show that the onset of the messinian salinity crisis is synchronous over the entire mediterranean basin dated at 5 96 0 02 million years ago isolation from the atlantic ocean was established between 5 59 and 5 33 million years ago causing a large fall in mediterranean water level followed by erosion 5 59 5 50 million years ago and deposition 5 50 5 33 million years ago of non marine sediments in a large lago mare lake sea basin cyclic evaporite deposition is almost entirely related to circum mediterranean climate changes driven by changes in the earth s precession and not to obliquity induced glacio eustatic sea level changes we argue in favour of a dominantly tectonic origin for the messinian salinity crisis although its exact timing may well have been controlled by the 400 kyr component of the earth s eccentricity cycle

how dry was the mediterranean during the messinian salinity crisis the messinian salinity crisis msc 5 97 5 33 ma is an enigmatic episode of paleoceanographic change when kilometers thick evaporite units were deposited in the mediterranean basin it is generally accepted that during the msc interval there was a dry climate in the mediterranean region it is difficult to assess how dry the climate was during the msc because a modern analogue in size and duration is absent here we reconstruct hydrological changes in the mediterranean basin during the three main msc stages using excellently preserved biomarkers we used the hydrogen isotopic composition of the long chain n alkanes dn alkanes to reconstruct the hydrological changes on the land adjacent to the mediterranean sea additionally the d of long chain alkenones dalkenones is used to observe changes in the mediterranean sea water source the dn alkanes recorded during the deposition of primary lower gypsum stage 1 in monte tondo indicate a d of the precipitation comparable to the present day mediterranean implying a similar hydrologic regime indicated by experiments modelling the miocene pliocene transition elevated dalkenones values from halite unit stage 2 of the realmonte mine are associated with kainite and giant polygons consistent with presumably high evaporative conditions during halite deposition the dn alkanes recorded during the deposition of upper gypsum stage 3 in eraclea minoa indicate a dprecipitation typical for much drier settings similar to the red sea region the relative contribution of the different alkenones from eraclea minoa is similar to the one observed in present day marine settings suggesting that during stage 3 connections to the open ocean were likely maintained however the dalkenones records during deposition of the evaporites in eraclea minoa are similar to those synchronously registered in the black sea implying that a similar hydrologic regime characterized by extended drought covered large areas of southeastern europe based on the dalkenones similarity and the paratethys type of lago mare fauna in the mediterranean we speculate that the surface water during stage 3 was at times derived from the black sea

upper messinian siliciclastic rocks in southeastern calabria southern italy palaeotectonic and eustatic implications for the evolution of the central mediterranean region abstract the messinian stratigraphy of eastern calabria southern italy is characterised by a threefold subdivision 1 a pelite section with local limestone and gypsum deposited in a restricted marine environment is unconformably or disconformably overlain by 2 coarse grained alluvial conglomerate which is in turn locally overlain by 3 a thin and discontinuous ribbon shaped sedimentary body of sandstone and pelite commonly displaying a shallow marine to continental progradational trend the basal unconformity disconformity coarse grain size and abrupt compositional sedimentological change of unit 2 with respect to unit 1 can be explained as a response to tectonic instability and out of sequence thrusting in the calabrian orogenic wedge possibly induced by isostatic back tilting of the wedge following the desiccation of the mediterranean sea this mechanism could explain widespread late messinian thrusting and syntectonic sedimentation along the apenninic maghrebian orogenic belt the uppermost messinian continental to shallow marine siliciclastic deposits of unit 3 crop out today at elevations of up to 300 m similar age equivalent sedimentary deposits can be traced along the apennines and the sicilian maghrebides thus indicating that the mediterranean area was flooded before deposition of the trubi formation the base of which is traditionally regarded as marking the reestablishment of marine conditions in the mediterranean region

gypsum salina coral reef relationships during the last interglacial marine isotopic stage 5e on the egyptian red sea coast a quaternary analogue for neogene marginal evaporites abstract in the tectonically stable area of the egyptian coast of the red sea the uppermost marine deposits of the last interglacial eemian 5e 5 5 marine isotopic substage consist of two contrasting sedimentary units a subcontinuous fringing coral reef and on its backward side shelly and subaqueous gypsum deposited in erosive depressions elongated parallel to the shore the entrenched geometry and the marine to brackish evolution of the pre evaporite faunas indicate that during this very short period of time a brief sea level drop responsible for the limited erosion separated the succession of reef to marine gypsum and that the coastal area underwent several climatic variations the marine ingression into drowned valleys early mis 5 51 developed khor environments non brackish lagoon on the arabic arid shores which were quickly replaced by highly restricted conditions leading to gypsum precipitation permanence of the salina waters and seasonal lamination interrupting crystal growth suggest an anchialine salina system littoral haline lakes fed by permanent seeping of sea water balanced by refluxing dense brines a semi arid climate is assumed with seasonal rains allowing limited continental sulphate contribution from miocene gypsum outcrops both climate and sea level changes were responsible for the complex evolution of this area compiled data enable generalization concerning the climatic oscillations during the last interglacial sedimentation a model derived from these red sea quaternary deposits as an analogue for the marginal miocene evaporite deposits in the mediterranean and red sea is discussed

aridity and humidity two aspects of the late miocene climate of north africa and the mediterranean abstract the physiography of north africa is not greatly changed from that of the messinian with the drawdown of the mediterranean in the late messinian the then existing river systems were incised into the landscape and emptied into lake cyrenaica which occupied the substantially drained eastern mediterranean basin the record of incision provides a record of the magnitude of the messinian river systems an analysis of these river systems demonstrates that messinian rainfall a consequence of the zeit wet phase was greatest in east and south central north africa in keeping with the derivation of the water mainly from the indian ocean in central north africa the eosahabi river flowed from messinian lake chad eroding the east tibesti valley and cutting a channel which is especially well preserved near the coast of the gulf of sirt the penetrated sediments of lake cyrenaica and the marginal basins of the messinian transgression are known as the upper evaporites and are generally fine clastics gypsarenites and gypsum anhydrite they were rapidly deposited underlying them is the halite of the lower evaporites this sequence of upper and lower evaporites is much like the lower halite of the tortonian south gharib formation and the overlying clastics and anhydrite of the messinian zeit formation in the gulf of suez red sea area this type of sequence is termed an evaporitic couplet and as has been demonstrated for the gulf of suez red sea is a consequence of a transition from a dry to a more humid climate in a restricted or semirestricted basin this transition occurred at about 7 5 ma in the gulf of suez red sea and at about 5 8 ma in the mediterranean the zeit wet phase manifest in the above events developed in association with the initiation and development of the asian monsoon and the drying of the mediterranean it can be understood in terms of the development of an evolving monsoon desert system the asian monsoon was initiated 8 7 ma in association with the uplift of tibet at this time the north african desert zone was displaced northwards to be over the mediterranean and central and eastern north africa became seasonally humid a concept is advanced in which the early stage of the development of the asian monsoon is seen as having two phases alternating at the precessional ca 21 ka cycle one phase transferred moisture from the indian ocean mainly to southern asia the other phase transferred moisture mainly to north africa with the drawdown of the mediterranean at about 5 8 ma the zeit wet phase intensified a further northward movement of the humid and desert zones occurred at the time of drawdown with the messinian and early pliocene transgressions the wet phase ameliorated but a substantial river system still crossed central north africa at about 4 6 ma north africa became drier probably in response to the developing dominance of the features of the monsoon that transferred moisture mainly to southern asia features of the monsoon that are well recognised today

paleoenvironmental changes at the messinian pliocene boundary in the eastern mediterranean southern cyprus basins significance of the messinian lago mare abstract the study of the late messinian early pliocene sediments in south cyprus pissouri and polemi basins and the comparison with the offshore coeval deposits drilled in the odp leg 160 boreholes provide new data illustrating the environmental changes which occurred in the eastern mediterranean at the end of the salinity crisis the messinian pliocene transition is marked by a very rapid environmental change indicated by sharp variations in lithology sedimentology microfaunal assemblages and stable isotope composition the latest messinian interval is dominated by the lago mare oligo mesohaline environments the most striking feature in the pissouri basin is the intercalation between the uppermost gypsum bed and the base of the zanclean deposits of four main horizons of paleosols interbedded with carbonates and conglomerates paleosols indicate periods of subaerial exposure long enough to permit pedogenesis to develop conglomerates indicate intense erosion of the troodos massif and its sedimentary cover as a result of the water level drop tectonic activity and more humid climatic conditions thus several subaerial exposure phases occurred in the marginal areas like the pissouri basin whereas shallow oligohaline conditions persisted in the deeper parts of the basin as indicated at odp site 968 both in the pissouri basin and on the flank of the erathostenes seamount the late messinian paleosols are directly overlain by the lowermost pliocene sediments deposited in well oxygenated deep marine conditions this drastic change of water depth shows that the water level of the late messinian saline to brackish lakes dropped far below that of the world ocean at least more than several hundred meters both these base level fluctuations and the oligohaline conditions caused intensive erosion karstification of the upper gypsum beds as also reported from many other mediterranean regions moreover the study of the polemi sections shows that oligohaline conditions had already started during the deposition of the upper gypsum sub unit typical brackish and fresh water assemblages are present in the last two gypsum layers and intergypsum beds this indicates that freshwater dilution i e the lago mare conditions resulted from a progressive change of the hydrological budget which started during deposition of the upper evaporites and climaxed after the deposition of the uppermost gypsum layer classical lago mare facies during this time periods of increased evaporation over precipitation led to deposition of the uppermost gypsum layers this evolution is interpreted as being due both to the severance from the open ocean and to the increasing contribution of the runoff precipitation versus marine inputs in the hydrological budget of the mediterranean

the age of the miocene pliocene boundary in the capo rossello area sicily detailed correlations of magnetostratigraphy biostratigraphy and lithostratigraphy reveal that the basal pliocene is equally complete in the eraclea minoa and capo rossello sections sicily and the singa section calabria and that in accordance with the model of the pliocene flooding event in the mediterranean the deposition of the pelagic marls of the trubi formation started synchronously on sicily and in adjacent calabria in addition the data obtained from the trubi in the eraclea minoa section allows the age of the miocene pliocene boundary to be adjusted slightly from 4 83 4 84 1 to 4 86 ma because downward extrapolation of both sedimentation rate and average duration of small scale sedimentary cycles in the trubi yields this age for the boundary in this section linearly interpolated ages for the top of the sphaeroidinellopsis acme and the first substantial increase in globorotalia margaritae the fod of this species is non existent in the mediterranean pliocene at eraclea minoa arrive at 4 74 and 4 63 ma respectively because of the detailed magnetostratigraphy and the very accurate dating of the miocene pliocene boundary it is preferable to select the eraclea minoa section as the boundary stratotype rather than the capo rossello section finally this age of 4 86 ma for the miocene pliocene boundary suggests that the beginning of the pliocene is connected with the termination of a series of latest miocene glaciations and that the re establishment of open marine conditions in the mediterranean might be of glacio eustatic origin

deep postseismic viscoelastic relaxation excited by an intraslab normal fault earthquake in the chile subduction zone abstract the 2005 mw 7 8 tarapaca earthquake was the result of normal faulting on a west dipping plane at a depth of 90 km within the subducting slab down dip of the north chilean gap that partially ruptured in the 2014 m 8 2 iquique earthquake we use envisat observations of nearly four years of postseismic deformation following the earthquake together with some survey gps measurements to investigate the viscoelastic relaxation response of the surrounding upper mantle to the coseismic stress we constrain the rheological structure by testing various 3d models taking into account the vertical and lateral heterogeneities in viscosity that one would expect in a subduction zone environment a viscosity of 4 8 1018 pa s for the continental mantle asthenosphere fits both insar line of sight los and gps horizontal displacements reasonably well in order to test whether the tarapaca earthquake and associated postseismic relaxation could have triggered the 2014 iquique sequence we computed the coulomb stress change induced by the co and postseismic deformation following the tarapaca earthquake on the megathrust interface and nodal planes of its m 6 7 foreshock these static stress calculations show that the tarapaca earthquake may have an indirect influence on the iquique earthquake via loading of the m 6 7 preshock positively we demonstrate the feasibility of using deep intraslab earthquakes to constrain subduction zone rheology continuing geodetic observation following the 2014 iquique earthquake may further validate the rheological parameters obtained here

evolution of depositional environments after the end of messinian salinity crisis in nijar basin se betic cordillera abstract the messinian succession is exceptionally well preserved in the intramontane sedimentary basin of nijar in the internal betic cordillera se spain gypsum olistostromes and large slabs of the azagador member are unconformably overlain by the latest messinian sediments of the feos formation these deposits which are studied in detail in the rambla los feos outcrop basinal area are characterized by a sedimentary cyclicity and two lithostratigraphic units can be distinguished 1 a lower one that mainly consists of calcarenitic intervals with laminated pelites and limestone beds 2 an upper unit showing a cyclic alternation of fluvial fan deposits and lacustrine marls that corresponds to the lago mare episode the sedimentary succession records very precisely the strongly fluctuating environmental conditions during the upper messinian as well as the paleomorphological and paleogeographical changes that are likely related to late miocene and pliocene tectonic uplift of the sierra cabrera betic basement the dominant fossil content present throughout the upper unit in the lacustrine white marls of the feos formation is represented by ostracods of the loxocorniculina djafarovi fa an assemblage of non marine aquatic communities which lived in brackish water bodies lago mare fauna extant ostracod faunas similar to those documented in the messinian fossil record and characterised by cyprideis tyrrhenocythere loxoconchids and leptocytherids occur in hypohaline water bodies in a salinity range of approximately 5 15 mesohaline water however the number of species of parathetian affinity is low as observed in other perimediterranean areas i e apennines the marine fauna association foraminifera present at levels is thought to be partly reworked even though a marine influence at the end of the lago mare stage is not excluded

palaeoenvironmental and palaeoclimatic evolution of the serres basin n greece during the miocene abstract the palaeoenvironmental and palaeoclimatic evolution of the serres basin from the end of mid miocene to the end of the miocene is examined lignites were deposited over a thick sequence of conglomerates and sands fossils found in the lignites indicate a lacustrine environment with tropical subtropical climatic conditions the climate became progressively drier and only small lakes were reserved during the messinian salinity crisis deposition of lake sediments finally ended with the world wide pliocene marine transgression a correlation of the serres basin with other lacustrine basins in the aegean area is attempted

the highland border rocks and their relation to marginal basin development in the scottish caledonides it has long been known that the highland border includes an assemblage of altered serpentinites gabbros spilitic lavas ferruginous and manganiferous cherts black phyllites quartzose clastics and amphibolites new work confirms that many of these rocks represent a dismembered tectonically emplaced ophiolite of caledonian age which originated in a narrow oceanic basin within or bordering the dalradian sedimentary pile the ophiolitic rocks were expelled from the basin as thrust sheets transecting d1 structures studies in the sw highlands suggest emplacement during d2 synchronous with se translation of the tay nappe this implies that the ophiolite originated in the n the highland border rocks are seen as marginal to a long lived northward dipping subduction zone within the southern uplands the evolution of the ballantrae ophiolitic complex the midland valley and the dalradian sedimentary basin are considered within this framework

alternate interpretation of the messinian salinity crisis controversy resolved a high resolution chronology of the mediterranean messinian salinity crisis is proposed two types of evaporite deposition may be distinguished those in marginal areas vs those in basinal ones their diachroneity is deduced from the stratigraphic relationships linking these evaporites to a major messinian erosional surface a two step model is proposed for the evolution of the salinity crisis through time during the first phase from 5 75 to 5 60 ma the deposition of marginal evaporites took place in response to a modest sea level fall in the second interval from 5 60 to 5 32 ma the mediterranean basin became isolated during this later period the deposition of basinal evaporites and the cutting of the mediterranean canyons took place

estuarine lago mare fauna from the tertiary piedmont basin indicates episodic atlantic mediterranean exchange during the final stage of the mediterranean salinity crisis abstract the geochemical signature of fossils from lago mare deposits at moncucco torinese nw italy indicates a temporary marine ingression into the tertiary piedmont basin just before the miocene pliocene boundary isotope 18o 13c 87sr 86sr and trace element sr ca ba ca data from mollusk shells of multiple species and croaker otoliths indicate an upper estuarine environment with considerable seasonal variability in evaporation and freshwater input reconstructed salinities the presence of a paralic paleobiotope with thalassogenic water in the tertiary piedmont basin contradicts ideas of the mediterranean as a brackish lake fed by the paratethys during the latest stage of the mediterranean salinity crisis instead our data support previous notions of temporary atlantic mediterranean exchange during sea level highstands preceding the permanent re connection at the miocene pliocene transition the establishment of short lived and disjunct estuarine and lagoonal environments such as in the tertiary piedmont basin during marine ingressions also puts highly variable 87sr 86sr values and occurrences of shallow water benthic foraminifera in lago mare deposits of other mediterranean basins into a new perspective

petrochemistry and tectonic significance of the highland border suite mafic rocks the metamorphosed mafic rocks of the ophiolitic highland border suite on arran and bute are of 2 types greenschist facies pillow lavas and epidote amphibolite facies hornblende schists respectively both types have been affected by post magmatic alteration processes including spilitization i e na enrichment coupled with ca depletion on the basis of 9immobile element9 chemistry and other criteria the mafic rocks are split into 2 magmatic groups a tholeiitic one which shows the effects of extensive low pressure fractionation e g fe and ti enrichment and a less fractionated alkaline group that contains relict al and ti rich clinopyroxenes the tholeiitic rocks are similar to modem ocean floor or marginal basin basalts and the alkaline rocks show affinities with 9within plate9 basalts this 9magma type9 and 9tectonic setting9 dichotomy is found at other highland border localities and is present in both the pillow lavas and hornblende schists the highland border suite mafic rocks may have formed as tholeiitic ocean basin crust upon which alkaline ocean island lavas had been erupted or alternatively as is suggested in this paper they may have formed during the early stages of development of a pre grampian marginal basin of cambrian or cambro ordovician age

ages and stratigraphical architecture of late miocene deposits in the lorca basin betics se spain new insights for the salinity crisis in marginal basins unlike most neogene basins of the betic cordillera where the salinity crisis is dated to the messinian a contradictory tortonian dating was proposed for evaporites of the lorca basin as a consequence complex structural models have been proposed in the literature to explain this discrepancy in the timing of evaporites in order to integrate the lorca basin into the geological context of the western mediterranean domain during the late miocene new sedimentological and stratigraphical studies coupled with new dating were performed which allow us to propose a messinian age for both diatomite bearing deposits and evaporites of the lorca basin these new ages challenge the idea of a tortonian salinity crisis in the lorca basin three main events of base level drop were evidenced during the messinian each event is correlated with successive steps of basin restriction shallow salina evaporites were deposited after a base level fall during the messinian before a final base level drop which led to the entire exposure of the basin this last exposure is interpreted as coeval with the deposition of first evaporites and halite in the deep mediterranean basins the reflooding which allowed the deposition of brackish deposits and a short lived marine incursion occurred at the end of the messinian base level drops occurred during eustatic falls amplified by the gradual uplift of the betic cordillera the exhumation of the tercia ridge along the strike slip alhama de murcia fault system during the messinian probably favoured the gradual restriction of the basin a discussion on correlations of main unconformities between several neogene basins of the betics is proposed suggesting a similar structural evolution at the regional scale

the significance of a reliable ordovician age for some highland border rocks in central scotland a lower arenig fauna with north american affinities has been rediscovered at dounans aberfoyle central scotland this discovery makes part of the highland border complex younger than the adjacent dalradian rocks and suggests a provenance from the s

ostracod faunas and brackish water environments of the late messinian sapigno section northern apennines italy abstract the sediments and ostracod assemblages from a small lacustrine basin located in the montefeltro area sapigno syncline romagna marche apennine central italy have been studied in detail from a section covering a broad interval spanning the late messinian post evaporitic sequence the latter consists of a non marine mainly terrigenous succession with molluscs and brackish water ostracods it represents the lago mare phase s s and is interpreted as shallow to relatively deep water lacustrine deposits characterized by a low salinity with occasional interactions with fluvial and littoral processes rich and diverse ostracod assemblages occur throughout the studied succession thirty species were recognized which characterize a loxocorniculina djafarovi fossil assemblage widespread in the western mediterranean during the latest part of the messinian it is a residual assemblage of a non marine fauna inhabiting hypohaline environments and testifies to the presence of large interconnected brackish water bodies lago mare along the margins and in the depths of a mediterranean basin isolated from the world ocean the ostracod faunas have paratethyan affinities but only a few species are common to both the western mediterranean and the eastern basins of paratethys