proxy climate and geomagnetic palaeointensity records extending back to ca 75 000 bp derived from sediments cored from lago grande di monticchio southern italy as part of a multi disciplinary study of maar lake sediments magnetic properties of some 3000 samples from two long cores extracted from the bottom sediments of lago grande di monticchio located in southern italy have been measured and the results connected with lithological palynological and geochemical data obtained from the same cores a time scale based on microlaminations radiocarbon and arar age determinations see companion papers in this special issue of quaternary science reviews dates the base of the longer 51 m core at about 76 ka before the present the strengths of anhysteretic remanence saturation isothermal remanence and susceptibility are highly sensitive to the contrast between stadial and interstadial conditions showing almost flip flop transitions at oxygen isotope stage 5a 4 and stage 2 1 boundaries as previously observed for lac du bouchet another maar lake site located in the haute loire province of france on the other hand these laboratory installed magnetizations vary smoothly through sediment deposited during stadials a prolonged period of heavy modelled precipitation starting at 25 ka bp coincides with a marked decrease in measured magnetic intensities possibly associated with the consequent increase in lake level and lake water chemistry the natural remanent magnetization is dominated by climatic and environmental influences nevertheless a weak signal attributed to variations in the palaeointensity of the geomagnetic field has been isolated and it shows good broad scale agreement with that previously reported for lac du bouchet

sound velocity of mgsio3 perovskite to mbar pressure abstract brillouin scattering measurements of the aggregate shear wave velocities in mgsio 3 perovskite were conducted at high pressure conditions relevant to the earth s lowermost mantle approaching 1 mbar infrared laser annealing of samples in a diamond anvil cell allowed us to obtain high quality brillouin spectra and to drastically extend the upper limit of pressure for brillouin measurements we found that the pressure derivative of the shear modulus d g d p g of mgsio 3 perovskite is 1 56 0 04 which is distinctly lower than that of previous lower pressure experiments below 9 gpa extrapolation of the high pressure shear velocities of perovskite to ambient pressure are in excellent agreement with earlier room pressure brillouin measurements the shear modulus shear velocity and longitudinal velocity at ambient pressure were determined to be g 0 172 9 15 gpa v s 6 49 3 and v p 10 85 3 km sec the mineralogical model that provides a best fit to global seismological 1 d velocity profiles is one that contains 85 90 vol perovskite in the lower mantle the results of this study are the first to demonstrate that the elastic wave velocities for a near adiabatic lower mantle with a bulk composition dominated by magnesium silicate perovskite are consistent with the average lower mantle seismic velocity structure the large pressure range over which acoustic measurements of mgsio 3 perovskite performed in this study has thus allowed us to put tighter constraints on compositional models of the earth s lower mantle

the valle del bove mount etna its origin and relation to the stratigraphy and structure of the volcano abstract the valle del bove is a major horseshoe shaped depression some 5 km in diameter and over 1000 m deep carved into the eastern flank of mount etna volcano the origin of the valle del bove has been a subject of debate for over a century but recent models relate it to the collapse of the ancient trifoglietto ii centre of etna either by caldera collapse or phreatomagmatic explosive activity careful morphological analysis shows the valle del bove to have formed after the post trifoglietto ii ellittico and leone centres and therefore to be considerably younger than the trifoglietto ii centre it has also been argued that the pyroclastic deposits that occur on the flanks of the volcano in close spatial relationship with the valle del bove were produced by the same event these pyroclastics are divided on the basis of age and composition into two groups the upper and lower tephra deposits the stratigraphy petrology and radiocarbon date of the lower tephra deposits indicate a trifoglietto ii age at least 20 000 years before the formation of the valle del bove the upper tephra deposits have a strong phreatomagmatic character and are closest in age to the valle del bove there is no evidence however to link them with its formation morphological study shows the valle del bove to consist of a series of coalescing scallops indicative of formation by landsliding the material removed by slope failure and subsequent fluvial transport followed a valley to the coast where it forms a fan shaped accumulation the chiancone consisting of volcaniclastics of fluvial and mudflow origin it is argued that the valle del bove did not result from simple caldera collapse but formed from a series of collapses caused by gravitational slope failure the chiancone is considered to be the product of this collapse

post collapse volcanic history of calderas on a composite volcano an example from roccamonfina southern italy roccamonfina part of the roman potassic volcanic province is an example of a composite volcano with a complex history of caldera development the main caldera truncates a cone constructed predominantly of this caldera may have been associated with one of the ignimbritic eruptions of the brown leucitic tuff blt around 385 000 yr bp the campagnola tuff the youngest ignimbrite of the blt however drapes the caldera margin and must postdate at least the initial stages of collapse during the subsequent history of the caldera there were several major explosive eruptions the largest of these was that of the galluccio tuff at about 300 000 yr bp it is likely that there was further collapse within the main caldera associated with these eruptions it is of note that despite these subsequent major explosive eruptions later collapse occurred within the confines of the main caldera between eruptions caldera lakes developed producing numerous lacustrine beds within the caldera fill extensive phases of phreatomagmatic activity generated thick sequences of pyroclastic surge and fall deposits activity within the main caldera ended with the growth of a large complex of basaltic trachyandestite lava domes around 150 000 yr bp early in the history of roccamonfina sector collapse on the northern flank of the volcano formed the northern caldera one of the youngest major events on roccamonfina occurred at the head of this northern caldera with explosive activity producing the conca ignimbrite and associated caldera there is no evidence that there was any linkage in the plumbing systems that fed eruptions in the main and northern calderas

cyclical slope instability and volcanism related to volcano tectonism in resurgent calderas the ischia island italy case study abstract the results of a detailed stratigraphic study carried out in the areas located to the east and south west of mt epomeo at ischia are presented and compared with those of previous geological archaeological and historical investigations to show the relationships among caldera resurgence volcanism and slope instability in the past 5 5 ka resurgence at ischia began at about 30 ka b p and occurred through intermittent uplifting and tectonic quietness phases during the past 5 5 ka reactivation of faults and related volcanic activity was accompanied by emplacement of deposits generated by surface gravitational movements these deposits were generated in four main phases dated between 5 5 and 2 9 ka around 2 9 ka between 2 6 and 2 3 ka and between 2 3 and 1 9 ka respectively deposits formed by gravitational movements preceded and followed the emplacement of volcanic rocks testifying that slope instability was induced by vertical movements which also activated and or reactivated faults and fractures that fed volcanism the results of this study therefore suggest that although slope failure can occur as a consequence of a variety of factors resurgence has to be considered a factor inducing a particularly intense slope instability resurgence is accompanied by activation of faults and renewal of volcanism causing oversteepening of the slopes and generating seismicity that could trigger surface gravitational movements furthermore the availability of large amount of loose material rapidly accumulated along the slopes during eruptions favors landslide generation

monte vulture volcano basilicata italy an analysis of morphology and volcaniclastic facies the earliest activity of monte vulture central italy included ignimbrites but the bulk of the volcano was built up by plinian airfall deposits contemporaneous remobilisation of these deposits formed an apron of lahars around the base of the main cone the volcano was constructed on a ridge the valley to the east and tributaries to the north and south became sediment traps for volcaniclastic materials emplaced by fluvial reworking and directly from volcanic activity to the west the valley was swept clear by active downcutting instability of the west flank as a result of this erosion was probably a contributory cause of major gravitational sector collapse on the volcano s flank terminating the main cone building phase the resultant scar is an amphitheatre shaped hollow called here the valle dei grigi previous workers have attributed this feature to coalescing calderas formed by engulfment the last volcanic phase was the production of the monticchio calderas and associated phreatomagmatic explosions producing airfall and surge deposits because most of the activity at vulture has been repeated plinian eruptions producing similar assemblages of products detailed stratigraphy of the volcano is difficult to accomplish to characterise vulture in terms of its products various facies are identified and interpreted in relation to volcanic processes distance from vent and environmental conditions

sedimentology dating and palaeoclimatic interpretation of a 76 3 ka record from lago grande di monticchio southern italy abstract detailed sedimentological and microstratigraphical investigations of lacustrine sediments from lago grande di monticchio southern italy provide a time scale based on rates of sedimentation obtained from annual laminations although not annually laminated throughout a time scale covering the last 76 3 ka is available by interpolation of sedimentation rates results of this chronology agree with radiocarbon dates and with ar ar dates on tephra layers from the same lacustrine sediment sequence occurrence of varves in combination with physical and geochemical properties are related to variations in the trophic state of the lake and to changing runoff both controlled by palaeoclimatic conditions water depth was relatively shallow with dominating bioturbation and only few varves preserved for most of the pleniglacial a marked increase in precipitation and related runoff characterises the early last glacial maximum when water depth reached a maximum and clastic varves were deposited subsequently water depth was shallower again a drastic change towards nutrient rich conditions occurred at the pleistocene holocene transition during the holocene organic varves were deposited two periods with higher organic productivity were recognised prior to the last glacial maximum around 50 ka and 73 ka these intervals are interpreted as the result of interstadial conditions the oldes of the two events shows laminations comparable to those at the glacial holocene transition the periods with increased minerogenic influx may be characterised as stadial conditions lasting from 14 40 ka and from 50 73 ka

lago grande di monticchio southern italy a long record of environmental change illustrated by sediment geochemistry abstract bulk geochemical analysis has been carried out on a 51 m sediment core from lago grande di monticchio in southern italy the record which may extend from the present back through more than one glacial cycle displays major variations in indicators of palaeoproductivity such as organic carbon and biogenic silica the most prominent change occurs at the holocene boundary lower in the sequence zones of moderately enhanced productivity highlight either interstadial or interglacial periods c n ratios and hydrogen indices provide possible indications of the sources and diagenetic state of the bulk organic matter but must be interpreted carefully as it is difficult to isolate the effects of these two factors changes in the clastic fraction e g na al ratio suggest that tephra deposition in the lake and its catchment has significantly altered the sedimentation this may also have influenced the biological productivity of the system

tephrochronology of a late quaternary lacustrine record from the monticchio maar vulture volcano southern italy abstract with the aim of defining the chronological framework of the 51 m deep sedimentary sequence core d from lago grande di monticchio mt vulture volcano macroscopic microscopic and geochemical investigations have been carried out on the 14 thickest at least 3 cm tephra layers recorded in the core the results indicate that the tephras are related to the main late quaternary explosive events from ischia vesuvius and the phlegrean fields districts of the campanian area following these results a usable time scale has been obtained according to which the sequence spans the last 70 ka beyond the chronological information this investigation has made it possible a to identify widespread time parallel markers for reliable correlations in the central mediterranean b to collect useful data about past powerful eruptions particularly from vesuvius for a better assessment of volcanic hazards in central and southern italy

subglacial erosion and englacial sediment transport modelled for north american ice sheets abstract reconstructions of north american glacial history have either been based on interpretation of the geologic record or on numerical models of continental ice dynamics because such models make no explicit reference to the geological products of glaciation the full potential of a combined approach has not been realized we present the results of a process based model of sediment production entrainment transport and deposition that represents a first step toward uniting these two lines of investigation in this model basal ice processes are dependent on ice sheet geometry hydrology and dynamics a three dimensional thermomechanical ice sheet model yields the ice geometry flow and thermal conditions that are used by a model of subglacial hydrology together these drive the basal process model comparisons of simulation results with mapped debris distributions of the hudson bay paleozoic carbonates and of the distinctive dubawnt group are used to test the validity of the transport model dispersion of debris radially out of hudson bay is greatly overestimated by the model and dispersion toward the bay equally underestimated this is because the modelled ice sheet has a single dome over hudson bay at glacial maxima including last glacial maximum rather than a saddle separating ice domes over quebec labrador and keewatin estimated rates of glacial erosion for the cordilleran and laurentide ice sheets are compared against those predicted by the model the model underestimates these rates because it underestimates the vigour of the quarrying process

petrogenesis of monte vulture volcano italy inferences from mineral chemistry major and trace element data the paper presents major and trace element data and mineral compositions for a series of foiditic tephritic to phonolitic rocks coming from monte vulture southern italy and investigates their origin evolution and relationship with the other centres of the roman province

chronostratigraphy of monte vulture volcano southern italy secondary mineral microtextures and 39ar 40ar systematics the eruptive history of monte vulture has been the subject of several geochronological investigations during the past decades which reliably dated only a small number of eruptions understanding the causes of sub optimum data yield in the past requires an interdisciplinary approach we re analyzed samples from previous works and present new data on samples from the main volcano stratigraphic units of monte vulture so as to provide an improved consistent chronostratigraphic database imaging of minerals by cathodoluminescence and backscattered electrons reveals that heterochemical high temperature deuteric reaction textures are ubiquitous such observations are common in metamorphic rocks but had not frequently been reported from volcanic rocks in view of the mineralogical complexity we base our chronological interpretation on isochemical steps defined as steps for which the cl k and or the ca k ratios are constant isochemical steps carry the isotopic signature of chemically homogeneous mineral phases and therefore allow a well constrained age interpretation comparison of old and new 39ar 40ar data proves the reproducibility of age spectra and their shapes this quantifies the analytical reliability of the irradiation and mass spectrometric analyses anomalous age spectra are a reproducible property of some specific samples and correlate with mineralogical anomalies the present data allow us to fine tune the age of the volcanostratigraphic units of monte vulture during the known interval of main volcanic activity from ca 740 to 610 ka after a very long stasis the volcanic activity in the monte vulture area resumed with diatremic eruptions one of which lago piccolo di monticchio the site of a palynological paleoclimatological drilling was dated at ca 140 ka

comments on monte vulture volcano basilicata italy an analysis of morphology and volcaniclastic facies by j e guest a m duncan and d k chester

a long pollen record from laghi di monticchio southern italy a preiminary account a pollen diagram from lake monticchio a volcanic crater lake in s central italy east of naples shows a long vegetation record for the holocene and the later portion of the last weichselian glacial period the upper 735 cm of a 2550 cm core is assigned to the holocene it begins with expansion of betula birch and quercus oak followed by fagus beech tilia lime and other mesic trees in the next phase the flora is dominated by oak with an increase in herb pollen in the later holocene the flora is again diversified by the appearance of abies fir curpinus hornbeam and other trees in the latest pleistocene portion of the core the vegetation is dominated by grasses artemisia sage brush and chenopods indicating a treeless environment the base of the core shows continued dominance by steppe like vegetation with 9interstadial9 episodes in which trees especially oak beech and fir were abundant the climatic interpretation is that the late pleistocene was very dry at least in the summer growing season and probably although not necessarily colder than now in the holocene increased precipitation favoured expansion of tree populations for a brief period there was a return of water stress in the growing season marked by a loss of tree species diversity and an increase in herbs in the later holocene a progressive diversification of tree species indicates a return to a more humid and perhaps cooler climate the vegetation history and climatic inferences are closely similar to records available from greece the available radiocarbon dates which show a consistent pattern indicate that the core is much older than 40000 years at the base but not old enough to include the major post eemian interstadials the 9holocene9 birch expansion began nearly 20000 years ago these dates appear to be systematically too old in the light of present knowledge the preliminary character of the study is emphasized further radiocarbon dates especially of the 9holocene9 section are needed as are more detailed studies of sedimentation processes and tephra occurrences

crystal chemistry of clinopyroxene from alkaline undersaturated rocks of the monte vulture volcano italy abstract the monte vulture is a late pleistocene stratovolcano composed of highly undersaturated alkaline potassic to ultrapotassic rocks belonging to the roman magmatic province these rocks are notably richer in na2o if compared to similar rocks of the roman province two distinct magmatic series have been recognized 1 feldspar bearing series ranging from basanite to phonolite and a volumetrically subordinate 2 feldspar free series consisting of melilitite melafoidite and hauynophyre the clinopyroxene compositions of the feldspar bearing series ranges from diopside to ferro salite hedenbergite and shows from basanite to phonotephrite increasing feotot al2o3 and tio2 and decreasing of mgo contents clinopyroxene in basanites and tephrites has generally high fe3 contents which is typical for clinopyroxene from the roman province clinopyroxene of the feldspar free series shows a more restricted variation in mgo and has often very high al2o3 feotot and tio2 contents in all the crystals examined the al3 content is high and is present mostly on the t site and for a minor part on the m1 site the m1 o2 distance shows a good correlation with the rm13 content clinopyroxene from basanites feldspar bearing series has the lowest rm13 and that from melilitite and hauynophyre feldspar free series the highest rm13 contents clinopyroxene crystals from feldspar free rocks have smaller m1 and larger t polyhedral volumes when compared to those in olivine melilitites and melilitites kamafugites from umbria but they show similar polyhedral volumes as clinopyroxene crystals from leucite bearing rocks although clinopyroxene from feldspar free rocks has small m1 volumes due to the high r3 contents m1 volumes of clinopyroxene from melilitites are larger than expected because of the higher fe3 al3 m1 values this larger m1 volume of clinopyroxene in melilitites causes a shortening of and a lengthening of the m2 o3 distance strong compositional and structural similarities between clinopyroxene of monte vulture and leucite bearing rocks of the roman province plagioclase bearing high potassium series hks indicate a common petrogenetic affinity on the other hand differences between clinopyroxene in feldspar free rocks from monte vulture and that in kamafugites i e olivine melilitites kalsilitites from central italy suggest significant magma dissimilarities between these two groups

magma evolution at mount vulture southern italy the vulture complex is made up of foiditic tephritic phonolitic trachytic and phonolitic products new rock analyses have been performed in order to ascertain whether the various rock types derive from a unique parental magma and if so to define its nature the data presented support that the vulture suite originated from a foiditic melt which had differentiated at low pressures the main process determining the foidite tephrite phonolitic trachyte evolution seems to be the crystal fractionation of mainly clinopyroxenes and opaques with the contribution of plagioclases and hauyne too in the tephrite trachyte evolution additionary role must have been played by a mixing of melts at different evolution stages occurred in a shallow seated magma chamber

the evolution of the monte vulture volcano southern italy inferences from volcanological geological and deep dipole electrical soundings data abstract the activity of monte vulture started in the middle pleistocene stratigraphic evidence suggests that the volcanic events may have occurred in the following succession 1 formation of widespread pyroclastic pumice deposits 2 sporadic and localized explosive and minor extrusive eruptions 3 highly explosive eruptions with the formation of some tuff cones and of the oldest part of the monte vulture central volcano and 4 activity at the central volcano initially mainly explosive and successively increasingly effusive the western part of the composite volcano and probably also its summit part were affected by caldera collapses the volcanic activity ended with hydromagmatic explosion which formed two explosion craters monte vulture was built up on the external units of the southern apennines at the western border of the foretrough the upper part of the sedimentary substratum consists mainly of clayey formations of the lagonegro and sannitic units beneath these terrains radiolarites and cherty limestones of the lagonegro units outcrop west of monte vulture rocks of the apulia carbonate platform were drilled east of the volcano deep dipole electrical soundings showed a resistant basement at a depth ranging from 0 2 km down to 4 3 km beneath monte vulture volcanological geological and geoelectrical data allow us to hypothesize that a the magma chamber could be located at the boundary between the rigid resistant basement and the overlying conductive plastic terrains b the apulia carbonate platform forms a structural high beneath the monte vulture and c the overthrusting of the lagonegro units on the apulia platform may be located beneath the floors of the calderas of monte vulture

digital photogrammetry as a tool in analogue modelling applications to volcano instability abstract three techniques of digital photogrammetry have been applied successfully to laboratory analogue models to study surface displacements caused by various volcano deformation types firstly side perspective videos are used to differentiate profile displacements between cryptodome intrusion models and models deforming by ductile inner core viscous flow both models show similar morphologic features including a bulged flank and an asymmetric upper graben however differences in displacement trajectories of the bulge crest reflect upward intrusion push contrasting with essentially downward displacement vectors of weak core models the other two techniques use vertical views correlated automatically either as time sequence monoscopic views or as coeval stereoscopic pairs this exploits to a maximum the method s potential by imaging surface displacements over the whole model successive monoscopic photograms because they suffer only moderate numerical processing for topographic effect removal can detect very small displacements occurring early in deformation processes as illustrated by analysis of intrusion models the monoscopic method allows prediction of fault locations and main displacement locations it can also anticipate the principal strain directions and separate different deformation stages on the other hand the stereo photogrammetry technique although more complicated provides topography and volume changes as well as pictures of surface displacements in three dimensions results are presented for the spreading of volcano models on a ductile substratum and viscous cored cones we have found digital photogrammetry to be a useful tool for analogue modelling because it provides quantitative data on surface displacements including movement invisible to the eye as well as topographic changes it is a good method for investigating and comparing different deformation mechanisms it is especially useful for interpretation of displacement patterns obtained from monitoring of natural active volcanoes in fact results of the methods used in the laboratory can be directly compared with field data from geodetic or photogrammetric surveys as at mount st helens in 1980

susceptibility measurements optical and x ray analysis to explain the origin of archaeological magnetic anomalies in tavoliere lowland southern italy since 2002 a non invasive investigation integrating aerial photography and high resolution magnetometry has been carried out for reconstructing extensive ancient settlements in tavoliere lowland southern italy relevant magnetic anomalies were detected in all the surveyed sites allowing a precise mapping of the buried structures over more than 150 ha next to this research susceptibility measurements pxrd xrf and optical analysis were also performed in order to explain the origin of the notable magnetization contrast between the anthropogenic structures and the embedding materials generating the measured signals this last study was accomplished in 2006 in monte s vincenzo site a vast neolithic village where the remotely sensed data were also used to guide some direct inspection trial archaeological excavations brought to light parts of c shaped compounds providing complete information on the geometry and location of the sources of magnetic signals profiting by the archaeological feedback the susceptibility contrast between the soil filling the ditches and the calcareous substratum was assessed in situ a synthetic model based on this information was created and compared with the experimental data the infilling material was also sampled for laboratory analysis the presence of several magnetic minerals pyroxenes monometric magnetite haematite was ascertained furthermore optical analyses showed different types of volcanic and igneous products such as pumices melanite garnets and lava fragments geomorphological and archaeometric evidence allowed us to relate these materials to activity of the mt vesuvius volcano eventually their possible spatial distribution was inferred from recent studies on ash transportation and deposition during explosive activity

characteristics of dune bedded pyroclastic surge bedsets abstract the grainsize characteristics of dune bedded pyroclastic surge bedsets are surveyed the variance between coarsest and finest beds ranges from 1 to 6 phi in different surge bedsets and it increases as the grainsize of the coarsest bed increases reflecting an increasing velocity of emplacement deposits of wet surges identified as those which contain accretionary and ash coated lapilli tend to be finer and show less variance this partly because wet ash is cohesive but mainly because wet surges tend to be weaker dry surge bedsets are strongly fines depleted wet ones less so the lack of erosion of underlying ash layers shows that the environment is a strongly depositional one individual bedsets are demarcated by thin intervening fine ash fall layers which are the complementary ash cloud deposits settled or flushed out after the passage and decay of each turbulent surge surge deposits are generally less coarse than the coarsest associated airfall deposits which shows that they are formed by generally weaker events this study helps interpret the dune bedded parts of the landscape mantling may 18th 1980 blast deposit of mount st helens the blast was a very violent event but the variance and the grainsize of the coarsest bed are those of a relatively weak surge this suggests that the dune bedding was produced by a weak effect such as minor turbulence in a thin pyroclastic flow coming to rest in a mountainous terrain roughened by tree stumps and fallen logs

character of the stress field in the calabrian arc and southern apennines italy as deduced by geological seismological and volcanological information abstract three crustal sections located in key zones of the calabrian arc and southern apennines have been drawn on the basis of the available geological geophysical seismological and volcanological data the purpose is to gather information on the state of stress at different crustal levels and to test to which extent data sampled at different time intervals may be consistently compared the analysis allows for the individualization of the following sectors 1 1 peri tyrrhenian belt marked by a tensional state of stress down to the moho depth 2 2 apenninic chain subjected to tension only in its shallow portions and to a compressive regime at depth 3 3 external chain internal foretrough characterized by a deep compressive regime which is expressed at the surface in its outermost zone only 4 4 external foretrough foreland with tensional processes in the whole crust compressional processes are linked to the activity of a deep shear zone which causes the thrusting of the tyrrhenian crust over the adriatic crust and which seems to control the present distortion of the calabrian arc the analysis suggests a change in the stress field and deformation mechanisms from the uppermost to the lowermost levels of the crust and an eastward migration with time of the compressional events these facts would explain the contrasting evidence sometimes given by stress constraints derived from geological seismological and volcanological data