influence of maturity on carbazole and benzocarbazole distributions in crude oils and source rocks from the sonda de campeche gulf of mexico abstract carbazole geochemistry has been studied for a petroleum system in which vertical migration is prominent and where reservoirs are locally sourced an essentially uniform organofacies of organicrich tithonian source rocks from the sonda de campeche gulf of mexico covering a well defined maturity sequence 0 36 1 29 rr and associated crude oils 0 49 0 92 rc from palaeocene reservoirs formed the sampling base comparison of the distribution of alkylcarbazoles and benzocarbazoles in rock bitumens and oils revealed that fractionation due to primary expulsion had no effect on the distribution of shielded exposed carbazoles within crude oils perhaps more importantly the benzocarbazole ratio in both rock extracts and crude oils increased with maturity indicating that this parameter cannot be directly used as a migration indicator in petroleum systems where vertical migration through faults and fissures represents the main avenues of oil migration

recent dyke induced large scale block movement at mount etna and potential slope failure here we report the results of a geodetic survey undertaken on mount etna between 1981 and 1988 observed horizontal ground movements in the vicinity of the valle del bove caldera demonstrate that dyke emplacement during 1983 and 1985 resulted in the 2 8 m eastward displacement of a block of western caldera rim a history of past instability and collapse along the rim is indicated by the presence of large back rotated blocks of prehistoric volcanics1 furthermore the unusually linear form of the present western rim indicates past slope failure along north south aligned surfaces and therefore that dyke induced collapse may have been an important agent in caldera enlargement we suggest a self sustaining mechanism whereby the stress regime generated as a consequence of the caldera s existence results in the repeated injection of north south orientated dykes adjacent to the western rim2 3 dilation associated with magma intrusion leads in turn to periodic phases of slope instability and failure of the cliff wall causing a progressive westward migration of the western rim

intrusive mechanisms at mt etna forerunning the july august 2001 eruption from seismic and ground deformation data in this work we present seismological and ground deformation evidence for the phase preparing the july 18 to august 9 2001 flank eruption at etna the analysis performed through data from the permanent seismic and ground deformation networks highlighted a strong relationship between seismic strain release at depth and surface deformation this joint analysis provided strong constraints on the magma rising mechanisms we show that in the last ten years after the 1991 1993 eruption an overall accumulation of tension has affected the volcano then we investigate the months preceding the 2001 eruption in particular we analyse the strong seismic swarm on april 20 24 2001 comprising more than 200 events mmax 3 6 with prevalent dextral shear fault mechanisms in the western flank the swarm showed a ca ne sw earthquake alignment which in agreement with previous cases can be interpreted as the response of the medium to an intrusive process along the approximately nnw sse volcano genetic trend these mechanisms leading to the july 18 to august 9 2001 flank eruption are analogous to ones observed some months before the 1991 1993 flank eruption and more recently in january 1998 before the february november 1999 summit eruption

late quaternary slip rates on the acireale piedimonte normal faults and tectonic origin of mt etna sicily abstract mt etna is located along the east coast of sicily near the boundary between the continental crust of the hyblean plateau and the mesozoic oceanic crust of the ionian basin the main active faults near mt etna cut the base of its eastern flank forming a 30 km long system of nne and nnw trending ene chelon fault segments the acireale piedimonte system showing dip slip and oblique right lateral motion most segments are associated with shallow depth seismicity and all have late pleistocene to holocene vertical slip rates ranging between 1 and 2 mm yr typical of major active normal faults worldwide eruptive fissures arranged in nne to ne trending zones cut the highest slopes of the volcano on the footwall of the normal fault system structural analysis suggests that current motions along both the active faults and eruptive fissures are kinematically compatible and simply linked with ongoing wnw ese directed regional extension such extension characterizes at a greater scale the active tectonics of southern italy where all large shallow historical earthquakes have remained confined within a narrow normal fault belt or rift zone stretching from the northern calabrian arc to southeastern sicily the southernmost west dipping faults of that rift zone in calabria aspromonte cut across the calabro peloritan thrust belt to join the mostly east dipping acireale piedimonte faults along the western boundary of ionian oceanic lithosphere which continues southwards as the malta escarpment we thus relate magmatism at etna to dilational strain on the footwall of an east facing crustal scale normal fault at the bend where the siculo calabrian rift zone veers 60 eastwards as it begins to cross the calabrian arc leaving the east facing margin of the ionian sea to catch up with the west facing margin of the tyrrhenian sea farther north

variations in the sterane carbon number distributions of marine source rock derived crude oils through geological time abstract the analysis of the sterane data of a large set of crude oils 414 derivedfrom marine carbonate 27 and siliciclastic source rocks 14 where influences of terrestrial or lacustrine derived organic matter can reasonably be excluded shows that there are increases in the relative content of c28 steranes and decreases in the relative content of c29 steranes through geological time there are no consistent variations in the relative content of c27 steranes through time with one major exception a proterozoic oil from oman palaeozolic and older crude oils are thus generally characterised by strong predominances of c29 steranes and low relative concentrations of c28 steranes significantly higher proportions of c28 steranes and lower proportions of c29 steranes occur in oils derived from jurassic and upper cretaceous source rocks these changes through time do not appear to reflect the chemical evolution of the sterols of one particular variety of marine organism the increase in c28 steranes may be related to the increased diversification of phytoplantonic assemblages in the jurassic and cretaceous possible sources of the c28 sterols necessary for the observed changes in crude oil steranes includes diatoms coccolithophores and dinoflagellates although the technique does not give an accurate means of determining the age of the source rock of a crude oil it is possible to distinguish younger crudes derived from the upper cretaceous and tertiary from palaeozoic and older crudes

variations in lava composition during the march 1981 eruption of mount etna and the implications of a compositional comparison with earlier historic eruptions the march 1981 eruption of mount etna occurred on the northern slopes of the volcano in an area previously inactive for more than 400 a a radial fissure system extending 7 5 km and producing 20 2 106 m3 of basic hawaiite lava opened at 2600 m a s l on 17th march and migrated downslope to 1125 m a s l where activity ceased on 23rd march gravity evidence points to the draining of a radial storage dyke located between sea level and 1 km a s l whole rock chemistry and petrography suggests that the magma in the dyke was a hybrid supporting crystal and compositional gradients developed as a result of progressively greater mixing of residual 1979 basic hawaiite magma with fresh basic hawaiite magma during permissive filling of the dyke around september 1980 these mixing gradients caused the eruption to display a significant contrast in the concentrations of al2o3 sr cao mgo and fe2o3 total between early high altitude and later low altitude products the fresh magma which entered the high level system around september 1980 ascended rapidly from a deep storage region at 16 24 km depth

coseismic displacements and creeping along the pernicana fault etna italy in the last 17 years a detailed study of a tectonic structure on a volcano abstract the pernicana fault is a tectonic fault located on mt etna sicily movements across this structure have been monitored over the last 17 years by a levelling network operated by the osservatorio vesuviano during the monitoring period the network has recorded coseismic displacements associated with earthquakes of magnitude 4 5 as well as aseismic displacements we present a detailed analysis of the displacement data aimed at modelling the geometry and mechanism of this fault as well as the size and mechanisms of individual earthquakes we use for interpreting the displacement data two types of inverse methods the first is able to determine from ground deformation data the geometry mechanism and location of a system rectangular faults with homogeneous dislocation the second finds for a fixed fault system geometry the heterogeneous slip distribution giving the best fit to the data the total recorded displacements during the last 17 years are well described by a single homogeneous rectangular normal fault with dislocation and size corresponding to a magnitude 5 7 earthquake thus revealing intense dynamics along such a fault coseismic displacements for individual earthquakes of considerable magnitude account for about 30 of the total deformation when interpreted in terms of an homogenous slip fault as inferred from total deformation some aspects of the data are not well explained thus calling for heterogeneous slip models it is hence possible with a certain approximation to distinguish the slip distributions associated with individual earthquakes from the almost homogeneous slip resulting from the sum of coseismic and aseismic movements the inferred seismic moments for the two larger earthquakes that occurred along this fault are considerable higher than reported in seismic bulletins about 1 degree of magnitude the results obtained here support the important role of levelling data for the detailed study of a peculiar kind of tectonic structure on a volcano aimed at understanding the complex interaction between volcano dynamics and induced movements along well defined structures

cave deposits as a sedimentary trap for the marine isotope stage 3 environmental record the case study of pod hradem czech republic pod hradem cave located in the moravian karst czech republic offers an excellent opportunity for environmental reconstructions of marine isotope stage 3 mis 3 in central europe due to its detailed sedimentary record dated 50 000 to 28 000 cal bp identifying the natural environments of the middle to upper palaeolithic mup transition is necessary to understand the settlement strategies and related behaviour of both neanderthals and anatomically modern humans both of whom may have occupied the region at the same time a multidisciplinary excavation was carried out between 2011 and 2016 detailed analyses of the sediments vertebrate microfauna pollen and charcoal revealed minor but observable fluctuations in climate with little change in the surrounding vegetation the pod hradem palaeoenvironmental dataset is complex but generally reflects a predominantly glacial climate with a range of vegetation types and habitats during the late pleistocene followed by the warmer and more humid holocene the mup transition as recorded in pod hradem cave was a glacial environment interrupted by two relatively warmer periods central europe experienced extreme climate fluctuations during mis3 as recorded from different sedimentary archives but it seems that the pod hradem cave environment may have acted as a buffer zone ameliorating those extremes and providing a suitable refuge for both bears seeking winter hibernation dens and occasionally visiting humans

the effects of thermal maturity on distributions of dimethylnaphthalenes and trimethylnaphthalenes in some ancient sediments and petroleums abstract the distributions of di and trimethylnaphthalenes in two sedimentary sequences from western australia have been examined by capillary gas chromatography and combined gas chromatography mass spectrometry a general decrease was observed in the relative proportions of dimethylnaphthalenes and trimethylnaphthalenes with increasing thermal maturity similar trends were also observed for six crude oils which have very different ratios of ethylcholestane epimers indicating very different thermal histories these results suggest that changes in the relative abundances of certain methyl substituted naphthalenes may be useful indicators of thermal maturity of sedimentary organic matter and the use of a number of isomer ratios is illustrated

three dimensional model of the feeder conduit of the 1983 eruption of mt etna volcano from ground deformation measurements a levelling network and a horizontal distance measuring network down mt etna s south flank were measured before during and after the 1983 eruption we analyse the large movements recorded using theoretical models of surface displacement to determine the shape and position of the feeder conduit that supplied magma to the eruption the results indicate that a dyke the top surface extending nearly horizontally connects the eruption site to a point near the southeast crater the top of the dyke lies at an altitude of 2400 m to 2500 m and dips between 75 and 90 to the west more tentative evidence indicates that the top of the active dyke dropped by about 150 m between the 25th and the 95th day of the eruption and that a small branching dyke 1 km long was emplaced to the east of the main dyke but did not attain the surface the implications of these observation are discussed

magma ascent simulations of etna s eruptions aimed at internal system definition the internal system of etna was studied by employing a nonequilibrium two phase flow model of magma ascent which accounts for different gas magma flow regimes and gas loss to surrounding conduit fractures when the magma pressure exceeds the local lithostatic pressure simulations of different phases of the 1974 and 1989 eruptions of etna with different flow regimes in conduits suggest that the pyroclastic strombolian lava fountaining and effusive lava flow activity can be modeled by effectively accounting for different physical processes of magma ascent results from simulations and geophysical and geological data suggest that magma ascent at etna may occur along a central conduit or inclined conduits from a magma storage region located from 8 to 9 km below the summit depending on the regional tectonic stresses and characteristics of the magma supply system the results also suggest the existence of a structurally weak zone from 1 to 4 km below the summit where magma may accumulate and from which fracture systems and magma ascent with gas loss to fractures may propagate to the eruptive vents at the surface the predicted excess magmatic pressure over lithostatic in the upper regions of conduits without gas loss to fractures suggests fracturing of the volcanic edifice during initial stages of eruptions and subsequent magma ascent and gas loss along these fractures modeling of the changes of activity at etna requires significant new efforts in geophysics aimed at high resolution internal system definition

seeking new potential in the early late permian gharif play west central oman west central oman is a relatively underexplored area where the hydrocarbons found to date occur mainly within the early late permian gharif formation structural definition of the low relief closures is hampered by seismic velocity variations caused by dune terrain recent exploration activity resulted in several gharif discoveries but highlighted reservoir distribution problems the gharif formation which consists of fluvio marine sediments conformably overlies the glacio lacustine sediments of the early permian al khlata formation it is overlain by shallow marine carbonates of the late permian khuff formation the main regional seal the area is located distally from the main sediment sources to the east reservoir development and lateral continuity are seen as the main risk most reservoirs are beyond seismic resolution only the stacked sandstones of the incised valley fills could provide sufficient acoustic contrast to be recognized on seismic geochemical typing indicates that the hydrocarbons in the gharif can be grouped in two main families the huqf and q hydrocarbons which are believed to originate from cambrian to precambrian source rocks although the two hydrocarbon families are sometimes found in one well they have very different spatial distributions the q oils form continuous strings of accumulations below the main regional seal whereas themore huqf hydrocarbons occur scattered throughout the area mixed accumulations are found where cross faults or salt domes intercept a q oil fairway future exploration activities will be guided by refined sedimentological stratigraphical and hydrocarbon migration models and by the continued efforts to recognize incised valley fills on seismic less

the influence of loading by lavas on the siting of volcanic eruption vents on mt etna abstract until now it has been considered that the positioning of magma conduits dykes and eruption sites on mt etna is controlled by stresses set up by regional tectonism it is also likely that gravitational stresses have some influence on the subsurface path taken by etnean magmas prior to eruption an additional effect discussed here is based mainly on convincing field evidence gathered over a number of years it is proposed that fracturing of the surface and changes in the stress pattern due to loading by recent lava flows may strongly influence the siting of eruptions detailed field observations are presented showing that cracks and fumaroles have consistently appeared round the edges of recent lava flows and that these cracks are sometimes later used by erupting lavas eruption statistics indicate that since 1970 50 of new eruptive vents have appeared within 80 m of a recent flow edge and field measurements show that downward flexure is still occurring at the edges of lava flows more than sixteen years old simple theoretical modelling indicates that this effect is strongest at the surface with gravitational and regional tectonic control of eruption sites dominating at progressively deeper levels

saturated hydrocarbon biomarkers in oils of late precambrian age from eastern siberia abstract large quantities of petroleum derived from source rocks of late precambrian early cambrian age have been discovered in the lena tunguska region of eastern siberia over the last twenty five years we have examined three oils with presumed late precambrian vendian source rocks from this region for c 15 saturated hydrocarbon biomarkers using gas chromatography gc and gas chromatography mass spectrometry gc ms our results show these oils to have many characteristics in common with other oils of similar age from eastern siberia and oman amongst the compounds detected in the three oils analyzed were 1 n alkanes which show a marine derived distribution 2 centrally branched monomethyl alkanes 3 acyclic isoprenoids pr ph 1 4 tricyclic and tetracyclic terpanes 5 hopanes 6 c 29 unrearranged steranes and 7 c 30 nuclear steranes all of these compounds with the exception of the 4 methylsteranes which on current biochemical knowledge are unexpected in oils of this age can be assigned a prokaryotic source this and other evidence such as the lack of diasteranes suggest microorganism were the major contributors to organic matter deposited as part of a carbonate source rock

the dhahaban petroleum system of oman the dhahaban petroleum system from a source rock of cambrian age covers some 50 000 km2 and contains 1 6 x 109 m3 of oil and 1000 x 109 m3 of gas in place of which at least respectively 0 35 x 109 m3 and 700 x 109 m3 are recoverable for many years the origin of the so called q oil was enigmatic and defied typing to a source rock integration of recent advances in geochemistry and basin modeling has now permitted us to retrace its source areas model the generation and migration histories and outline the areal and stratigraphic extent of the petroleum system

changes in mid and far field human landscape use following the laacher see eruption c 13 000 bp abstract around 13 000 years ago the laacher see volcano east eifel volcanic field rhenish shield erupted cataclysmically the thick tephra blanket in the eruption s near field covered and thereby preserved a large number of archaeological sites ranging from very small to some of the largest and richest sites known from the late glacial in this proximal region there is a striking contrast in the number of sites prior to the eruption and the almost complete lack of sites dating to the period after the event i e to greenland interstadial 1a the preservative function of the tephra cover itself may explain this near field pattern but it is shown here that similar stratigraphic observations can also be made in the laacher see eruption s mid field towards the west and in particular to the north east the aim of this paper is to review the stratigraphic relations of known archaeological sites outside the near field of the laacher see event with a particular focus on the german federal state of hesse and adjacent areas of lower saxony and the thuringian basin here a number of archaeological sites are known where strata of laacher see tephra cap human occupation most often these sites are not reoccupied until much later in prehistory suggesting that the eruption may have led either to a complete or a near complete abandonment of the affected regions or at the very least to a major reorganisation of landscape use

changes in the stress regime and displacement field in the interior of mount etna deduced from surface observations abstract if measurements of all three components of displacement at the surface of a mountain are available the stress strain relations of the theory of linear elasticity can be used as a simple approximation to obtain insight into changes that take place on a relatively short time scale in its interior if such a simple elastic model is employed interpolated values derived from these data can be used as boundary conditions at the surface of the mountain and then integrated downwards this procedure yields values for the internal displacements that take place from year to year from which changes in the internal stress distributions can be calculated the location of regions in which the solutions obtained by this approach give inappropriate results indicate where the assumptions of linear elasticity do not hold and so provide further evidence in the task of determining internal structure measurements are available from 1987 to 1992 for all three components of displacement at a substantial number of points on the surface of mount etna in intervals of not more than a year and the method was applied to them to obtain evidence of regions in the interior of the volcano deserving further study

dynamic inversion of ground deformation data for modelling volcanic sources etna 1991 93 the 1991 93 etna eruption that represented the most important recent eruptive event both in terms of duration 472 days and total volume of erupted lava ca 250 106 m caused marked ground deformation measured by using different geodetic techniques such as edm gps levelling and tiltmetry an inversion termed dynamic because it took into account the sequence of events considering both the separate and cumulative effects of two sources a shallow tensile crack and a deeper ellipsoidal deflating source was performed it was based on 163 data collected by the different techniques plus 2 geometrical conditions for constraining the geometry of the crack on the surface the final solution furnished a good fit for all measurements defining a shallow tensile crack located inside the volcanic edifice which represents the effect of the intrusion and a depressuring body with centre at ca 3000 m b s l which could represent the centre of a generalized and more complex deflation of the volcanic edifice during the course of the eruption

timescales space and culture during the middle palaeolithic in northwestern france abstract northwestern france is characterized by the presence of many middle palaeolithic sites covering the entire period the saalian phase is less documented partly for taphonomic reasons the lithic industries indicate mastery of all production systems for flakes blades points and to a lesser extent bifaces during the upper pleistocene occupation of this territory by neandertal groups is important the vast majority of these lithic series cannot be attributed to cultural facies of mousterian defined by bordes due to the low number of retouched tools aside from some typical mousterian of acheulean tradition bifaces and blade production characteristic of the early weichselian which are stylistic and cultural markers there is nothing to differentiate mousterian groups in an attempt to identify their cultural identities lithic assemblages were apprehended globally using the operative sequence concept from the acquisition of raw material to the final objectives of the different production systems and abandonment of tools the situation is considered from each chronostratigraphic phase to try to distinguish the settlement patterns of this region this renewed approach to technical studies points to a wide diversity of neandertal adaptive faculties which can be interpreted in terms of cultural diversity

sediments of biśnik cave poland lithology and stratigraphy of the middle palaeolithic site abstract bi nik cave is an important palaeolithic site located in the krakow czestochowa upland the cave fill is a complex well stratified sequence composed of 35 layers sublayers interrupted by number of hiatuses and ranging from pliocene till modern times fifteen middle palaeolithic horizons some of them among the oldest in poland represent the most important part of the sequence from an archaeological point of view the sedimentary sequences in particular parts of the cave have been studied for more than 20 years to investigate the chronostratigraphy and palaeoenvironment the recent multi proxy study is based on the application of new methods for the site analysis of sedimentary and post sedimentary structures and weathering stage of limestone rubble and fossil bones pollen analysis molecular biomarkers palaeomagnetic analysis and radiometric dating results indicated a more intensive role of re working and re deposition in the cave older sediments were transported into some stratigraphic horizons from sources within the cave itself as well as from outside including palaeontological and archaeological materials some the detected layers therefore represent a mix derived from different sources a record of two interglacials eemian interglacial mis 5e and penultimate interglacial mis 7 was established in layers nos 15 14 13a 13 and 19a 19 respectively middle upper pleistocene sedimentary units were identified with mis 3 mis 7 8 instead of previous interpretation to mis 4 mis 9 the age of the basal vario colored complex previously interpreted mostly as pre pleistocene was newly correlated with mis 7 8 and early pleistocene pliocene

importance of gravitational spreading in the tectonic and volcanic evolution of mount etna the interaction between gravity and thermal effects largely determines the structural and magmatic evolution of volcanic constructs at scales spanning several orders of magnitude from small cones to the oceanic crust1 3 although gravitational spreading is a direct consequence of this interaction and a fundamental process in volcano growth it is rarely recognized as such here we describe a striking example of this process at etna volcano in italy the volcano and its clay rich substratum are slowly spreading towards the east and south driven by gravity spreading produces extensional structures in the summit region and contpressional structures at the base of the volcano eastward movement of the volcanic edifice over a stationary magma supply may be the cause of an apparent westward migration of volcanic activity as gravitational spreading seems to control the location and magnitude of shallow seismicity and flank eruptions an appreciation of its effects could become an essential element of future volcanic hazard evaluation our model proposed here for etna may also be relevant to a reinterpretation of the geological history of a number of other volcanoes

mathematical modelling of the stress regime in mount etna using ground deformation measurements 1987 1992 abstract the stress strain relations of the theory of linear elasticity can be used as a simple approximation to the far more complicated relations that necessarily exist inside a volcano in order to obtain insight into changes that take place on a relatively short time scale or near the surface where stresses and temperature distributions are not so great as to suggest that other equations ought to be applied they are here used to study the stress distribution at the surface of mount etna when the edifice of the volcano is distorted by movements of magma or by straining in the structures below sufficient observational data exists to deduce the changes in the surface stress distribution resulting from the observed deformations this approach indicates that the regions of maximum stress most likely to lead to fissuring occur round the edge of the valle del bove

chronostratigraphic context of the middle to upper palaeolithic transition recent data from belgium abstract the chronological and palaeoenvironmental context for the industries identified in europe during the middle to upper palaeolithic transition mupt is not accurately known this situation is mainly due to insufficient knowledge of the context of the archaeological data much of which comes from old excavations any major progress in the understanding of the mupt can only be achieved with the study of long sedimentary sequences providing a semi continuous record and situating archaeological remains in a reliable palaeoenvironmental and chronological framework strict attention must also be paid to stratigraphic control and site formation processes interdisciplinary studies undertaken over the last ten years in belgium contribute to research on the mupt belgium plays an important role due to its specific geological context that includes many caves a well developed loess cover which acts as a reference sequence for the upper pleistocene and the presence of tephras this enables detailed reconstruction of climatic change and more accurate chronological control in cave sequences initial results from new fieldwork on long sequences are presented here walou and scladina caves as well as the open air site of maisieres canal combined with results of recent analyses on old material mainly from the spy and trou de l abime collections they enable establishment of a reliable and more accurate chronostratigraphic framework for the archaeological assemblages and provide new data on the humans responsible for them thus around 45 000 bp a mousterian industry was made by neandertals in trou de l abime around 40 000 38 000 bp belgium was still occupied by neandertals associated with a typical middle palaeolithic as shown in walou the spy neandertals have recently been directly dated by 14c to 36 000 bp but the techniques of the early excavations prevent clear identification of the associated industry still the 14c results are more coherent with the lincombian ranisian jerzmanowician lrj chronology than the mousterian both of which are identified at spy the earliest convincing age for the belgian aurignacian is about 32 000 33 000 bp maisieres canal and spy

paleoecological and climatic implications of stable isotope results from late pleistocene bone collagen ziegeleigrube coenen germany abstract climatic and ecological conditions during marine oxygen isotope stage mis 3 are complex and the impact of cold spells on the ecosystems in central europe still needs to be investigated thoroughly ziegeleigrube coenen zc is a late pleistocene mis 3 locality in the lower rhine embayment of germany radiocarbon dated to 34 14 c ka bp the site yielded a broad spectrum of mammal species we investigated the carbon 13 c nitrogen 15 n and sulfur 34 s isotope signatures of bone collagen since these are valuable tools in characterizing ecological niches environmental conditions and aspects of climate and mobility by comparison with pre and post last glacial maximum lgm sites in central europe we show that zc belongs in a cold event of mis 3 and was climatically more similar to post lgm sites than to pre lgm sites however the trophic structure resembled that of typical pre lgm sites in belgium this cold event in mis 3 changed the bottom of the foodweb but do not seem to have had a direct impact on the occurrence of the mammalian species and their ecological distribution apparently the mega faunal community could adapt also to harsher environmental conditions during mis 3

a new cambrian black pigment used during the late middle palaeolithic discovered at scladina cave andenne belgium abstract sedimentary unit 1a at scladina cave belgium has yielded archaeological material from a middle palaeolithic occupation dating to between 40 210 400 350 bp and 37 300 370 320 bp fifty one fragments of a black friable rock with a black streak were found in association with 194 burned bone fragments and several thousand lithic artefacts this black material is interpreted as a pigment brought to the site by neandertals the pigment was analysed by petrography xrd raman microspectroscopy and other geochemical methods it was identified as a highly siliceous graphitic siltstone this is a very unique discovery as european archaeological research has so far only recorded black pigments comprised of manganese oxides from the middle palaeolithic raman microspectroscopy is a non destructive method able to distinguish the attributes of black siliceous materials that originate from different tectono sedimentary contexts by measuring the degree of alteration of the carbonaceous material this method allowed for the determination of its geographical and geological origins a cambrian formation of very limited extent located near ottignies about 40 kilometres north west of scladina cave the absence of a drainage network connecting the two locations eliminates the possibility of natural transport and supports its anthropogenic origin

the relationship between late quaternary deformation and volcanism of mt etna eastern sicily new evidence from the sedimentary substratum in the catania region abstract stratigraphical and structural analyses have been carried out on the late quaternary foredeep succession forming the etnean substratum in the catania region eastern sicily in order to investigate in detail the chronology of deformation events that have accompanied a significant period of the eruptive activity of mt etna i e from 240 ka to the present this episode was characterised at about 200 ka by a main change of the petrochemical features of the emitted products from sub alkaline to alkaline this can be related to an evolving mantle diapir located beneath the volcano the new stratigraphical and structural field data presented in this paper constrain the development from 240 to 125 ka of nw se trending dextral faults associated with minor e w to ne sw oriented accommodation thrusts and nnw sse trending normal faults that originated in a dominant transpressive regime strike slip tectonics were active during the earlier emissions of sub alkaline lavas 320 200 ka old and part of the ancient alkaline products 180 100 ka old from scattered eruptive systems which developed in local transtensive zones distributed throughout the whole etnean region a major change in the mode of deformation since 125 ka bp was related to the propagation of a normal fault belt along the ionian coast of the catania region and the eastern sectors of the etnean edifice this process was associated with the growth of open folds that deformed the entire foredeep sequence exposed along the southern boundary of the etnean edifice during this period eruptive activity concentrated along the main extensional features where steady and very efficient feeding systems originated this resulted in a rapid increase in the volume of emitted alkaline products that gave rise to the construction of the modern stratovolcano during the last 80 ka the collected data emphasise some main aspects of the relationship between tectonic deformation at a regional scale and volcanism in the etna area firstly the mode of deformation at the onset of etnean volcanism seems to be inadequate to explain the emplacement at depth of a mantle diapir related to the occurrence of a hotspot almost independent from the local crustal dynamics on the other hand the late quaternary structural assemblages recognised on the surface can be interpreted as direct effects of the europe africa convergence rather than as the products of deformation induced by the emplacement of the mantle diapir in the different stages of etnean evolution a direct relationship exists between the mode of deformation and the distribution as well as the capacity of the feeding systems in particular the amounts of emitted products in the different stages depend on the intensity of crustal stretching associated with deformation rather than the volume of available molten material at depth these conclusions represent a new perspective for the interpretion of the early stages and subsequent evolution of the volcanic activity of mt etna the proposed model also represents an useful tool in deciphering the relationship between the deformation path seismicity and volcanic activity of mt etna

effect of maturity and petroleum expulsion on pyrrolic nitrogen compound yields and distributions in duvernay formation petroleum source rocks in central alberta canada abstract a quantitative study of pyrrolic nitrogen compounds was conducted on a series of marine carbonate petroleum source rock extracts taken from the upper devonian duvernay formation in the central alberta portion of the western canada sedimentary basin with increasing thermal maturity concentrations of various pyrrolic nitrogen compounds in the rock extracts increase drastically together with significant compositional variations related to alkyl substitution position the study provides circumstantial evidence for adsorptive interactions operating between organic nitrogen compounds and solid organic mineral phases in subsurface sedimentary rocks during petroleum generation and expulsion the absolute concentrations and relative distributions of pyrrolic nitrogen compounds in the extracts of different maturity ranges provide background information for the calibration of such data in migrated petroleums as an independent measurement of secondary oil migration range of duvernaysourced oils in the basin

growth and evolution of an emergent tuff cone considerations from structural geology geomorphology and facies analysis of sao roque volcano sao miguel azores abstract the syn eruptive and post eruptive history of sao roque tuff cone its geological setting and volcanological features were studied in detail to understand the role played by the different factors that contributed to the morphological evolution of this relatively simple and small volcanic edifice in addition attention was also focused on the series of natural changes that affected the tuff cone during the course of the years and that finally led to its structural disassembly a novel model is proposed to explain this process the sao roque volcanic centre located on the island of sao miguel azores consists of two well consolidated bodies and numerous small islets that formed more than 4700 years ago during the hydromagmatic activity that took place along an intruding dyke whose nnw sse trend is in agreement with the regional tectonic pattern the eruptive vents probably migrated progressively from sse to nnw forming small edifices through the rapid accumulation of sediments during alternating phases of dry and wet magmatic emissions syn eruptive partial collapses greatly modified the original morphological structure of these edifices probably allowing sea water to continuously flow into the vents the complex interaction of these factors controlled the depth of magma fragmentation producing different types of deposits in which the ash lapilli ratio varies considerably the high water saturation degree of these deposits caused syn eruptive and post eruptive remobilization which resulted in collapses and some small scale landslides post eruptive wnw ese trending transtensional and extensional tectonic activities operated during the initial dissection of the cone generating instability furthermore the rapid accumulation of wet tephra and its following consolidation caused selective collapses that favoured the fragmentation of the deposit and caused the formation of numerous islets separated by radially arranged channels collapses also involved the lava units emplaced in more recent times around the tuff cone which show that brittle deformation has been significant in the area for a prolonged period

recent deep earthquake occurrence at mt etna sicily italy abstract the seismic activity of mt etna from april 1988 until the december 1991 eruption was monitored by means of permanent and temporary seismic networks volcanic activity that occurred during this period tremor increase with lava fountains at the summit craters and eruptions was preceded and accompanied by the occurrence of deep z 15 km seismicity this deep seismic activity occurring a few days up to some weeks before the volcanic phases was characterized by typical mainshock aftershocks sequences focal mechanisms of the more energetic events which preceded the eruptions show that the compression axis was nearly north south parallel to the direction of the compressive stress field acting in the area at regional scale both the observation of deep seismicity occurrence also before or during previous eruptions and the role played by tectonics as controller of the magma uprise suggest the hypothesis of a relation between the seismic energy released in the volcanic basement and the recharge mechanisms of the volcanic system in this hypothesis the deep seismicity located in the etnean area could be considered as a possible forerunner of volcanic activity

the effect of biodegradation and water washing on the occurrence of alkylphenols in crude oils abstract biodegraded oils from california and nigeria were analysed to assess the impact of biodegradation upon alkylphenol occurrence in crude oils the extent of biodegradation in the 13 californian samples ranged from very mild full n alkane distribution present to moderate complete degradation of c 15 n alkanes and significant reduction of acyclic isoprenoids corresponding to a range of n alkanes and acyclic isoprenoids stage 5 the data from the naturally degraded sample suites were compared to the results of an in vitro aerobic biodegradation experiment conducted with a north sea oil biodegradation resulted in significant reduction in total alkylphenol abundance and preferential depletion of c 3 and c 2 alkylated compounds in the nigerian and laboratory degraded samples these effects were most pronounced in oils in which the methylated naphthalenes had been biodegraded biodegradation stage 4 or 5 there was no clear relationship between alkylphenol abundance or molecular distributions and the extent of biodegradation in the californian samples although alkylphenol distributions in the biodegraded samples were generally dominated by the c 3 compounds simple oil water partition calculations showed that these distributions were consistent with the effects of water washing

geochemical study on a well in the western canada basin relation of the aromatic distribution pattern to maturity of organic matter abstract thirty one rock samples from a western canada basin well have been analysed for aromatics using glass capillary gas chromatography with simultaneous flame ionization and sulfur selective flame photometric detection a uniform aromatic distribution pattern with a marked predominance of di and tricyclic aromatic hydrocarbons was observed throughout a depth interval of 3000 meters comprising cretaceous and jurassic sediments the very high relative abundance of sulfur aromatics at two narrow intervals in the triassic and mississippian is attributed to a major change in facies gradual changes with increasing depth have been observed for a series of compound ratios which had been calculated from the isomers of methyl and dimethylphenanthrene and their parent compounds these changes reflect the increasing thermal maturation of the sedimentary organic matter a methylphenanthrene index mpi has been introduced which exhibited a very good correlation with vitrinite reflectance data the mpi is the first maturity parameter which is based on a series of aromatic hydrocarbons this hydrocarbon internal maturity parameter permits the recognition and definition of maturity levels in extracts which can be compared to the maturity e g vitrinite reflectance of source rocks

variation in alkylphenol distributions in a homogenous oil suite from the dhahaban petroleum system of oman as part of a study to determine the effect of migration processes on the abundance and distribution of alkylphenols in crude oils we have analysed a homogeneous suite of 15 oils from the dhahaban petroleum system in oman that lies along a secondary migration pathway in a foreland basin setting geochemical parameters based on aliphatic hydrocarbon biomarkers and aromatic hydrocarbon concentrations and ratios suggest a similar maturity and source facies for the oils despite the wide variation in relative petroleum migration distance up to c 260 km given the similarity in source facies and maturity characteristics of the oils we conclude that the observed variations in alkylphenol concentrations in this sample suite are controlled mainly by secondary migration processes the majority of the oils are not degraded and in these samples we observe a significant decrease in total alkylphenol concentration within the first c 50 km relative migration distance supporting similar studies on north sea petroleum systems and suggesting that alkylphenols may be useful as geotracers over shorter migration distances there is little evidence of systematic migration distance related variation in the relative abundance of individual alkylphenol isomers or homologue groups the alkylphenol distributions in two biodegraded oils in the sample suite both from relatively shallow reservoirs were dominated almost completely by phenol and this is discussed in the context of the microbial production and alteration of phenols and the influence of water washing on the content and distribution of phenols in crude oils

structural features of the july august 2001 mount etna eruption evidence for a complex magma supply system we describe the evolution of the volcanic activity and deformation patterns observed at mount etna during the july august 2001 eruption seismicity started at 3000 m below sea level on 13 july accompanied by moderate ground swelling ground deformation culminated on 16 july with the development of a ne sw graben c 500 m wide and c 1 m deep in the cisternazza area at 2600 2500 m above sea level on the southern slope of the volcano on 17 july the eruption started at the summit of mount etna from the se crater central lateral eruptive system from which two radial c 30 m wide c 3000 m long fracture zones associated with eruptive fissures propagated both southward 17 july and northeastward 20 july on 18 july a new vent formed at 2100 m elevation at the southern base of the montagnola followed on the next day by the opening of a vent further upslope at 2550 m eccentric eruptive system the eruption lasted for 3 weeks approximately 80 of the total lava volume was erupted from the 2100 m and the 2550 m vents the collected structural data suggest that the cisternazza graben developed as a passive local response of the volcanic edifice to the ascent of a north south eccentric dyke which eventually reached the ground surface in the montagnola area 18 19 july in contrast the two narrow fracture zones radiating from the summit are interpreted as the lateral propagation from the conduit of the se crater of north south and ne sw oriented shallow dykes 2 3 m wide the evolution of the fracture pattern together with other volcanological data magma ascent and effusion rate eruptive style petrochemical characteristics of the erupted products and petrology of xenoliths within magma suggest that the eccentric and central lateral eruptions were fed by two distinct magmatic systems examples of eccentric activity accompanied by central lateral events have never been described before at etna

occurrence and distribution of high molecular weight hydrocarbons in selected non marine source rocks from the liaohe qaidam and tarim basins china abstract extracts of 18 potential source rocks from the qaidam liaohe and tarim basins china have been characterized by high temperature gas chromatography htgc and found to contain high molecular weight hydrocarbons hmwhcs above c40 these rocks were originally formed in freshwater lacustrine saline lacustrine and terrigenous bog environments with mudstone calcareous mudstone coaly shale and coal lithologies their ages range from triassic to miocene and maturities from immature to mature covering a vitrinite reflectance range ro for the liaohe and tarim samples of 0 54 0 84 the combined distributions of the n alkane and alkylcyclopentane homologues in the extracts can be used to characterize the nature of the original depositional environment in certain samples the carbon number predominance of the n alkanes changes from an odd even predominance to even odd predominance above c40 possibly suggesting different precursors for the n alkanes above and below c40 concentrations of the hmwhcs were also observed to increase with maturity of the source rocks this is the first comprehensive report on the occurrence of hmwhcs in source rocks and their discovery introduces the possibility of using these compounds for oil source rock correlation purposes in future studies along with the more conventional biomarkers

geochemical characteristics and significance of heteroatom compounds in lacustrine oils of the dongpu depression bohai bay basin china by negative ion fourier transform ion cyclotron resonance mass spectrometry abstract saline and freshwater lacustrine oils from the dongpu depression bohai bay basin were characterized by negative ion electrospray ionization esi fourier transform ion cyclotron resonance mass spectrometry ft icr ms esi ft icr ms detected a large range of nitrogen and oxygen compounds in the oils mostly comprising n1 o1 o2 and n1o1 species the low mature oils are dominated by o1 species with double bond equivalent of 4 dbe 4 mainly alkylphenols o2 species with dbe 5 6 i e hopanoid secohopanoic and steroid acids and dbe 1 i e fatty acids indicating a genetic relationship between oxygen compounds and their precursors the nitrogen and oxygen compounds were significantly influenced by maturity with the lower maturity oils analyzed enriched in o2 species particularly fatty acids and 4 5 ring naphthenes with biologically sourced hydrocarbon skeletons ratios of o2 n1 0 7 c20 30 c15 45 dbe1 o2 0 4 and dbe5 6 dbe12 22 o2 6 0 may be useful indicators of low maturity with increasing maturity the condensation degree of the compounds increased and the carbon number decreased the relative abundances of n1 and o1 species with the following specific dbe carbon number ranges were particularly sensitive to maturity dbe9 12 dbe15 18 n1 c20 28 c29 40 dbe12 n1 c20 30 c31 50 dbe15 n1 dbe9 12 dbe4 20 o1 and c20 30 c31 50 dbe8 o1 in some instances the ft icr ms proxies provided a more reliable indication of high maturity levels than traditional sterane based maturity parameters however several of these species were also responsive to other influences namely c20 28 c29 40 dbe12 n1 and c20 30 c31 50 dbe15 n1 ratios reflected an organofacies control and dbe9 12 dbe4 20 o1 and c20 30 c31 50 dbe8 o1 ratios changed with thermochemical sulfate reduction tsr confirmed by 34s variances of oscs in light of the multiple controls on the nitrogen and oxygen compounds dbe9 12 dbe15 18 n1 ratio seems unaffected by organofacies or tsr and was considered the most reliable maturity proxy displaying a similar or better maturity relationship than ts ts tm aside from secondary alteration effects the freshwater samples showed several compositional differences to the saline samples albeit from a limited data set including generally higher o2 and n1 particularly low mw product abundances lower abundances and quite different distribution of o1 products these distinctions suggest esi ft icr ms analysis has potential for distinguishing these sample types

bayesian inversion of 1994 1998 vertical displacements at mt etna evidence for magma intrusion summary we have developed a bayesian method for the inversion of static ground deformations at volcanic areas the method allows inference of the conditional probability density on the location and mechanism of point sources representing volcanic phenomena isotropic strain nuclei tensile faults embedded in homogeneous elastic media the method has been tested with simulated and real data from volcanic areas we have then analysed vertical displacements recorded at mt etna southern italy from 1994 to 1998 by high precision levelling measurements in this period had been carried out yearly so resulting displacements have been analysed both in consecutive periods and in the cumulative one measurement periods 1994 1995 and 1997 1998 show significant uplift of several centimetres the maximum cumulative displacement amounts to 6 5 cm with a trend similar to each of the two periods 1994 1995 and 1997 1998 the shape of displacement is well approximated by a circular symmetry thus allowing one to hypothesize an isotropic overpressure model as the source simulating magma intrusion at shallow depth the application of the inverse method gives the most probable location at about 4 5 km of depth b s l at about 1 5 km north of the central craters the 95 per cent of probability density is concentrated within a radius of about 0 5 km on the horizontal 1 km on depth the obtained results give important insight on the interpretation of recent eruptive episodes

high precision relocation of microearthquakes at mt etna 1991 1993 eruption onset a tool for better understanding the volcano seismicity abstract the beginning of the 1991 1993 large eruption at mt etna was marked by a seismic swarm and a sudden increase of volcanic tremor amplitude several earthquakes were recognized as clusters of shallow events with nearly identical waveforms multiplets we have analyzed these signals with a cross spectral technique that allows us to locate the relative position of the events within a multiplet obtaining a precision higher than with traditional routines the relocated shocks occurred some kilometers away from the propagating eruptive fracture east of both the summit craters and the modeled eruptive dykes they clustered in a relatively small volume elongated in the nnw sse direction the depth of which ranged from about 1100 to 2000 m below sea level these earthquakes are interpreted as the passive brittle response of the volcanic basement to the intrusion of the eruptive dyke rather than being directly linked to the magma transport

neanderthal and animal karstic occupations from southern belgium and south eastern france regional or common features abstract karstic systems have preserved abundant archaeological records with well represented faunal remains due to their sedimentological and topographical features these particular localities were intensely exploited and occupied by neanderthal groups we focus here on middle palaeolithic settlements from the last glacial period mis 5d 3 which is characterized by marked climatic variability with colder episodes alternating with more temperate periods the ardeche region in south eastern france and the meuse basin in belgium have recently been the focus of regional studies combining archaeological geological and chronological data in order to bring to light human land use and subsistence strategies these two areas comprise multiple rock shelters and caves with neanderthal occupations dating from mis 5d to 3 as well as the obvious traces of occupation by neanderthals most sites provide evidence of carnivore occupations e g cave bears cave hyenas or wolves each of these habitation sites presents a specific topography and type of occupation and most of them reveal behavioural homogeneity within their sequences by comparing data from faunal accumulations in these two related areas separated by a distance of about one thousand kilometres we attempt to gain a better understanding of the driving forces behind neanderthal and animal occupations of karstic networks do regional land use patterns exist in different european karstic localities or can we perceive common features related to the geography and topography of the sites

missing records and depositional breaks in french late pleistocene cave sediments abstract cave entrance and rock shelter infillings are positioned within the pleistocene chronology for three areas of france northern alps franche comte and perigord despite minor local variations it is possible to identify regional types with a consistent depositional record over long intervals of time the interregional variability relates to the frequency and position of the gaps within the infillings sites in the northern alps have not yielded any artifacts older than the upper paleolithic magdalenian and dated sedimentary sequences do not go back beyond the older dryas more complete sequences in franche comte contain mousterian industries two major gaps occur here one lasting about 50 000 yr during the lower glacial and lower pleniglacial periods and the other lasting some 10 000 yr during the upper pleniglacial the sequences are more complete in the perigord where all major climatic phases have been identified with no significant sedimentary gaps differences in sedimentary records can be explained by variations in regional conditions during the last interglacial glacial cycle and especially by the distance from the maximum advance of ice daring glaciation

loess in a cave lithostratigraphic and correlative value of loess and loess like layers in caves from the krakow czestochowa upland poland abstract although debris loams and clays are usually regarded as typical cave sediments loess and loess like sediments are common among clastic cave deposits in the near entrance facies of caves and rock shelters late weichselian loess layers are very common in caves from the krakow czestochowa upland and were recognized in almost each excavated cave and rock shelter these layers were initially dated to the lgm last glacial maximum but new chronometric dating results are available that allow us to present a more detailed scheme of the geological age of the series this paper evaluates the significance of polish in cave loess layers as correlative horizons we present the lateral and vertical stratigraphy and lithological variability of cave loesses and their usefulness as lithostratigraphic markers these features are especially important for archeology and paleontology as cave sediments including loess are usually the carriers of archeological and paleontological material

the chemical structure of a pronounced series of iso alkanes in south oman crudes gas chromatograms of the saturated hydrocarbon fractions of the south oman crudes are characterised by a striking series of peaks called x peaks throughout this paper eluting between the n alkanes mainly in the c20 c26 range a gs ms study combined with optimised gc resolution shows that each peak is a superposition of subpeaks which correspond to a complex series of monomethylalkanes the x20 peak in the chromatogram for instance is found to be composed of virtually co eluting peaks corresponding to 5 6 7 8 9 and 10 methylnonadecane the larger x22 x23 and x24 peaks are superpositions of a similar set of monomethylalkanes and in addition a series of presumably dimethylalkanes of which the structures are only partly solved the large abundance of these iso alkanes is very specific for south oman crudes and may be caused by their pre cambrian origin or a specific source material

tectonic control on the eruptive dynamics at mt etna volcano sicily during the 2001 and 2002 2003 eruptions abstract the eruptive events of the july august 2001 and october 2002 january 2003 at mt etna provide new insights for reconstructing the complex geometry of the feeding system and their relationship to regional tectonics the 2001 eruption took place mainly on the upper southern sector of the volcano the eruption was preceded by a large earthquake swarm for a few days before its onset and accompanied by ground deformation and fracturing the development of surface cracking along with the seismic pattern has allowed us to recognize three distinct eruptive systems the sw ne nnw sse and n s systems which have been simultaneously active such eruptive systems are only the upper portions of a complex feeding system that was fed at the same time by two distinct magmas the sw ne and nnw sse systems connected with the se crater conduit were fed by magma coming from depth whereas the n s system served instead as an ascending pathway for an amphibole bearing magma residing in a shallow reservoir the eruptive activity started again on october 2002 on the ne rift zone where about 20 eruptive vents were aligned between 2500 and 1900 m a s l and on the southern flank from the central crater to the montagnola the onset of eruptive activity was accompanied by a seismic swarm as in the 2001 eruptive event two independent feeding systems formed characterized by distinct magmas the sw ne system controlled the feeding of the northeast rift and was accommodated by left lateral displacement along the wnw ese trending pernicana fault the n s system fed the eruptions on the southern flank moreover the associated crustal deformation triggered seismic reactivation of tectonic structures in the eastern flank of the volcano and offshore these two last eruptions indicate that at mt etna the ascent of magma as well as the accommodation of deformation is strongly dominated by local extensional structures that are connected to a regional tectonic regime

mechanisms for ground surface fracturing and incipient slope failure associated with the 2001 eruption of mt etna italy analysis of ephemeral field data abstract during the july august 2001 eruption of mt etna development of extensional fractures faults and grabens accompanied magma intrusion and subsequent volcanic activity during the first days of the eruption we performed an analysis of attitude displacement and propagation of fractures and faults exposed on the ground surface in two sites torre del filosofo and valle del leone located along the same fracture system in the region surrounding the valle del bove depression on the eastern flank of mt etna fractures and faults formed as the consequence of a shallow intruding dyke system that fed the several volcanic centres developed along the fracture system the investigated sites differ in slope attitude and in geometrical relationships between fractures and slopes in particular the fracture system propagated parallel to the gentle slope

fast deformation processes and eruptive activity at mount etna italy the seismic and deformation patterns observed on mount etna before and during the 1991 1993 eruption the third largest since the seventeenth century in terms of lava volume are consistent with the regional tectonic framework of eastern sicily the pattern of the stress field acting on the intermediate and lower crust was defined at the local scale by focal mechanisms of microearthquakes occurring at depths between 10 and 25 km beneath the volcano they provide evidence for a strike slip compressional stress regime with the maximum compressive component acting approximately n s the fault plane solutions and the spatial and temporal distribution of seismicity indicate that usually sinistral shear ruptures occur along approximately ne sw trending fault zones while dip slip ruptures affect approximately nnw sse trending fault zones the latter include the avenues along which magma ascended during the 1991 1993 eruption seismic observations indicate a local inversion of the stress field acting on the upper crust depth 10 km underlying mount etna which was initiated less than 2 months before the eruptive event and disappeared with its end this is consistent with a local tensile regime that favored the magma ascent through the shallow crust the events preceding the eruption and accompanying its onset tilt anomalies and seismic swarms and those occurring shortly after its beginning a mainshock aftershock seismic sequence and associated coseismic tilts provide important evidence for understanding the dynamics of the two main volcano tectonic structures ne sw and nnw sse trending fault zones and associated intrusive mechanisms on etna the shape and location of the eruption feeding dike have been modeled from ground deformation data this approximately nnw sse modeled dike the seismicity and the position of the fractures are consistent with the regional stress field characterized by 1 oriented approximately n s the geophysical data presented and analyzed in the present paper strongly suggest an overall regional tectonic control as well as an active role for the intruding magma in the dynamics of the volcano

shear response to an intrusive episode at mt etna volcano january 1998 inferred through seismic and tilt data abstract the space time evolution of a seismic swarm m d max 3 7 occurring on 9 14 january 1998 at mt etna volcano is analysed the hypocentral pattern and most reliable focal mechanisms indicate that seismic activity during 10 14 january mainly occurred within a fault zone located in the volcano s western flank the fault showed an approximately ne sw overall trend and shallow rupture mode of right lateral strike slip type it is noteworthy that earthquakes occurring during the initial phase 9 january of the swarm showed prevalent dip slip rupture mechanisms which are consistent with tensile opening of an approximately nnw sse trending fault zone this nnw sse structural lineament belongs to a regional lithospheric structure which has also been identified as a main volcano genic structural trend of mt etna the observed continuous tilt data are not explainable by the seismic slip associated with strain released along the ne sw structure however an intrusive source would be compatible with the rupture mechanisms observed during the initial phase of the swarm and could explain the observed tilt therefore we evidence that an intrusive episode occurred along the nnw sse structure starting 9 january and during the following days it forced the ne sw fault system to work in a right lateral mode these mechanisms leading to the february november 1999 summit eruption are analogous to the ones observed before the 1991 93 eruption

deformation induced gravity changes in volcanic regions summary we analyse a new model to estimate the change in gravity and in elevation caused by volcanic eruption or inflation in the new model a permeable porous zone surrounds a spherical magma chamber magma may enter or leave the magma chamber and independently the permeable zone this arrangement simulates the flow processes inferred from field studies and provides a degree of freedom not available in the classic model proposed by mogi and used by many others since then we find in agreement with field data and previous analyses of the mogi model that the change in edifice volume is smaller than the volume of magma which produces it the local change in gravity is found to be proportional to the local elevation change the constant of proportionality being positive or negative depending on whether magma flow is directed into or out of the chamber or infiltrated zone

mt etna volcano modelling of ground deformation patterns of recent eruptions and considerations on the associated precursors abstract the study of the ground deformation associated with the recent eruptions of the etna volcano 1981 1989 1991 93 furnished the opportunity to observe different behaviour relating to the eruptive activity and suggested different feeding and penetration mechanisms inside the volcano edifice in particular the analytical modelling of geodetic data was applied to study the strain sources of these eruptions by the application of single and multiple source models i e composed of two single sources in particular a single tensile dislocation was used to model the se fracture associated with the 1989 eruption a double tensile dislocation was adopted to interpret and model the deformation pattern of the 1981 eruption a double source composed of a tensile dislocation for the final eruptive fracture and a depressuring body for the deflation during the eruption course was considered for the 1991 93 eruption the results of this modelling show that however the final uprising system i e the tensile mechanisms inside the volcano edifice involved the same structure oriented approximately nnw sse this structure was activated by different eruption mechanisms with associated different deformation patterns during these three recent eruptions a review of the methodologies applied and main results obtained in modelling of different sources and mechanisms is presented here the analysis of the deformation data and the performed modelling evidence that the associated precursors can strongly change for the different eruptions in addition the implications both in terms of how the volcano works and in terms of ground deformation precursors are discussed

the occurence of unusual c27 and c29 sterane predominances in two types of oman crude oil abstract two types of oman crude oils reveal unusual sterane distributions type a which is the more common 74 examples is characterised by a predominance of c 29 iso and normal steranes and generally none or only very low relative concentrations of rearranged steranes the triterpanes are characterised by the predominance of the c 29 17 h 21 h norhopane over the c 30 17 h 21 h hopane and non predominant c 20 c 30 tricyclic terpanes the c 29 steranes of this type of crude were not derived from the c 29 sterols of land plant origin frequently proposed as the source of c 29 steranes since there is good geological evidence that these crudes were generated from a pre cambrian source rock a geological period when land plants did not exist the type b crude oil 11 known examples is characterised by a strong predominance of c 27 iso normal and rearranged steranes relatively lower concentrations of 17 h 21 h hopanes and relatively high concentrations of c 20 c 30 tricyclic terpanes the remarkably different biomarker characteristics of these crude oils imply that the organisms active in the depositional environment of the respective source rocks were significantly different

surface deformation in volcanic rift zones abstract the principal conduits for magma transport within rift zones of basaltic volcanoes are steeply dipping dikes some of which feed fissure eruptions elastic displacements accompanying a single dike emplacement elevate the flanks of the rift relative to a central depression concomitant normal faulting may transform the depression into a graben thus accentuating the topographic features of the rift if eruption occurs the characteristic ridge trough ridge displacement profile changes to a single ridge centered at the fissure and the erupted lava alters the local topography a well developed rift zone owes its structure and topography to the integrated effects of many magmatic rifting events to investigate this process we compute the elastic displacements and stresses in a homogeneous two dimensional half space driven by a pressurized crack that may breach the surface a derivative graphical method permits one to estimate the three geometric parameters of the dike height inclination and depth to center and the mechanical parameter driving pressure rock stiffness from a smoothly varying displacement profile direct comparison of measured and theoretical profiles may be used to estimate these parameters even if inelastic deformation notably normal faulting creates discontinuities in the profile geological structures open cracks normal faults buckles and thrust faults form because of stresses induced by dike emplacement and fissure eruption theoretical stress states associated with dilation of a pressurized crack are used to interpret the distribution and orientation of these structures and their role in rift formation

impulsive tilt variations on mount etna volcano 1990 1993 abstract this study was focussed on the analysis of the fast ground deformations impulsive anomalies recorded at the mt etna tilt array from 1990 to 1993 a period that preceded accompanied and followed the 1991 1993 eruption these fast deformations were recorded as transient anomalies ranging from a few hours to days 1 2 observed contemporaneously at several tilt stations and characterized by variations ranging from one to tens of microradians the signals evidenced volcanic dynamics characterized by tilt anomalies during the non eruptive periods 1990 1993 the pre eruptive period november december 1991 the beginning of the eruption 14 15 december 1991 and the eruption course 1992 in particular pre seismic co eruptive and co seismic anomalies were recorded during the pre eruptive period and the eruption onset in these cases interpretations of the phenomena and comparison to modelling studies are provided furthermore tilt variations affecting the global volcanic edifice were also observed one year before the eruption when they were followed by seismicity and during the eruption course without seismicity we interpreted this last class of tilt variations as due to the push of the magma uprising along the main nnw sse structure crossing mt etna

the feeding of the eruptive activity of etna volcano the regional stress field as a constraint to magma uprising and eruption an analysis of the structural lineaments as observed on the middle and upper slopes of etna volcano was made with the aim of checking stress distribution within the volcanic structure

the modern human colonization of western eurasia when and where dating the timing of the replacement of local neandertal populations by modern humans in western eurasia at the dawn of the upper palaeolithic remains challenging due to the scarcity of the palaeontological evidence and to the complexity of the archaeological record furthermore key specimens have been discovered in the course of excavations that unfortunately did not meet today s archaeological standards the importance of site formation processes in the considered time period makes it sometimes difficult to precisely assign fragmentary remains a posteriori to distinct techno complexes the improvements in dating methods have however allowed for the clarification of many chronological issues in the past decade archaeological and palaeontological evidence strongly suggest that the initial modern colonization of eastern europe and central asia should be related to the spread of techno complexes assigned to the initial upper palaeolithic this first expansion may have started as early as 48 ka cal bp the earliest phases of the aurignacian complex protoaurignacian and early aurignacian seem to represent another modern wave of migrations starting in the levant area the expansion of this technocomplex throughout europe completed the modern colonization of the continent the interpretation of a third group of industries referred to as transitional assemblages in western and central europe is much debated at least in part these assemblages might have been produced by neandertal groups that may have survived until c 41 ka cal bp according to the directly dated neandertal specimens of saint c france and spy belgium 2014 the author published by elsevier ltd this is an open access article under the cc by nc nd license http creativecommons org licenses by nc nd 3 0