mirdita zone ophiolites and associated sediments in albania reveal neotethys ocean origin the mirdita ophiolite zone in albania is associated with widespread melanges containing components of up to nappe size we dated matrix and components of the melange by radiolarians conodonts and other taxa the components consist of radiolarites pelagic limestones and shallow water limestones all of triassic age as well as ophiolites triassic radiolarite as a primary cover of ophiolite material proves middle triassic onset of mirdita ocean floor formation the melange contains a turbiditic radiolarite rich matrix radiolaritic flysch dated as late bajocian to early oxfordian it formed as a synorogenic sediment during west directed thrusting of ophiolite and sediment cover nappes representing ocean floor and underplated fragments of the western continental margin the tectonic structures formed during these orogenic events younger kimmeridian or eohellenic orogeny are sealed by late jurassic platform carbonates the geological history conforms with that of the inner dinarides and adjoining areas we therefore correlate the mirdita pindos ophiolite zone with the vardar zone and explain its present position by far distance west directed thrusting

geological evolution of the albanian ophiolites and their platform periphery geological studies of the tectonic zones of eastern albania indicate that they represent the passive margin to a neotethyan mirdita ocean basin situated on the western margin of the korab pelagonian microcontinent

towards a field test for fracture propagation propensity in weak snowpack layers slab avalanche release requires fracture initiation and propagation in a weak snowpack layer while field tests of weak layer strength are useful for fracture initiation the challenge remains to find a verified field test for fracture propagation we introduce the two current versions of a field test for fracture propagation propensity and report results of testing conducted in the columbia mountains of british columbia canada during the winter of 2005 by extending the column of a stability test approximately 3 m in the downslope direction the test method allows for the development of a flexural wave in the slab and thereby maintains the contribution of this wave and the associated weak layer collapse to the fracture process fracture lengths collected on a day and location where the propagation propensity of the snowpack was locally high show a bimodal distribution with approximately 50 of observed fractures similar to those collected in stable snowpacks and approximately 50 with much longer fracture lengths

zabyat formation semail nappe oman sedimentation on to an emplacing ophiolite the pelagic sediments of the semail ophiolite are depositionally overlain by ophiolite derived sediments of the zabyat formation dominated by matrix supported rudites with subordinate arenites and lutites the detritus was locally derived from the ophiolite in a deep marine environment indicated by both underlying and overlying pelagic carbonates the zabyat rocks are restricted to fault zones in the ophiolite which were active during emplacement they are interpreted as debris shed from the sub vertical fault zones during the initial disruption of the semail ocean floor prior to the final emplacement on to the arabian continental margin this interpretation places constraints on possible mechanisms of ophiolite emplacement

filling in the gaps the contribution of non pollen palynomorphs to knowledge about the local environment of the sierra de atapuerca caves during the pleistocene abstract for several decades conventional pollen analyses have been supplemented with information provided by non pollen palynomorphs npp generally the taxa included in this group are microalgae fungi insects and arachnid s chitinous remains as well as plant debris and other organic palynomorphs of undetermined origin that are valuable tools with which to characterise the original strata as well as the local environmental features that influence deposit formation processes in this work we present the results of the npp analysis of the archaeological and palaeontological deposits of sima del elefante gran dolina and galeria all of which are located in the trinchera area sierra de atapuerca burgos spanning a period from 200 ka to almost 1 5 million years ago the npp analysis of the three deposits has provided information about the presence of decayed organic matter accumulations erosion processes and moisture conditions knowledge of palynomorphs contributes to the understanding of the biological physical and chemical dynamics that resulted in different sedimentary sequences in almost all cases there is a clear connection between the major stratigraphic trends established for the three deposits and the npp assemblages identified however the eminently local character of the dispersion of most of the palynomorphs identified has prevented the interrelation between the three sequences analysed

evolution of multilevel caves in the sierra de atapuerca burgos spain and its relation to human occupation abstract the evolution of the torcas cave system sierra de atapuerca is analysed in order to shed light on the formation of the atapuerca archaeological sites and human occupation in the area critical for identifying the paths of the first human dispersal into europe the geomorphological analysis of the endokarst system and the regional base levels has revealed a multilevel cave system with drainage directions from south to north where old karst springs fed the pico river using morphological and topographic evidence we have correlated the fluvial terraces situated at relative heights of 84 80 m and 78 70 m above the arlanzon river main course with the first and second cave levels respectively both of early pleistocene age the fluvial levels t4 60 67 m and t5 50 54 m are linked with the third level early middle pleistocene which contains fluvial deposits probably related to terrace t6 44 46 m progressive fluvial incision allowed humans to gain access to the cave system through several entrances from 1 22 myr until the end of the middle pleistocene when these cave entrances became filled forming the most interesting hominid bearing deposits in europe

pleistocene sedimentary facies of the gran dolina archaeo paleoanthropological site sierra de atapuerca burgos spain abstract gran dolina is a cavity infill of the sierra de atapuerca containing three important early and middle pleistocene archaeo paleontological layers including hominid bones fauna and lithic remains due to the relevance of this site to understand human evolution in europe it is essential to define in detail the sedimentary processes and environments associated with the archaeological remains gran dolina has a 19 m thick sedimentary infill divided into 11 lithostratigraphic units in this work we describe the sedimentary facies of the early and middle pleistocene units and we update its stratigraphy for that purpose we have studied the stratigraphic excavation profiles available where we have combined field observations with laboratory sedimentary analysis sieving laser diffraction and image analysis to characterize the texture and structure of the sediments through these studies 19 sedimentary facies have been distinguished grouped as sediment gravity flow facies fluvial facies and autochthonous facies the facies associations indicate two main trends in the allochthonous sequence during the early pleistocene td4 td7 the cavity acted as a stream sink where channel and floodplain facies migrated along the sequence and were interbedded with lateral gravity sediment flows on the other hand the middle pleistocene sequence between td7 and td10 is dominated almost exclusively by gravity flows at least three main entrances have been inferred from input directions of the sediments which changed over time sediment characteristics have allowed us to preliminarily infer environmental conditions around the cavity

acoustic emission signatures prior to snow failure snow slab avalanches are caused by cracks forming and propagating in a weak snow layer below a cohesive slab the gradual damage process leading to the formation of the initial failure within the weak layer wl is still not entirely understood to this end we designed a novel test apparatus that allows performing loading experiments with large snow samples 0 25 m 2 including a wl at different loading rates and simultaneously monitoring the acoustic emissions ae response by analyzing the ae generated by micro cracking we studied the evolution of the damage process preceding snow failure at fast loading rates the exponent of the ae energy distribution b value gradually changed and both the energy rate and the inverse waiting time increased exponentially with increasing load these changes in ae signature indicate a transition from small to large events and an acceleration of the damage processes leading to brittle failure for the experiments at slow loading rate these changes in the ae signature were not or only partially present even if the sample failed indicating a different evolution of the damage process the observed characteristics in ae response provide new insights on how to model snow failure as a critical phenomenon

mesozoic tertiary tectonic evolution of albania in its regional eastern mediterranean context abstract research carried out since the opening of albania to the western geological community in the 1990s allows the geology and tectonics of this small balkan country to be integrated into an overall interpretation of neotethys in the eastern mediterranean region specifically greece and the former yugoslavia region albanian geology is most famous for the occurrence of contrasting ophiolites of jurassic age the country is sub divided into three main geotectonic units those in the west i e sazani ionian kruja krasta cukali and the albanian alps relate to the western margin of apulia effectively part of north africa from early mesozoic time onwards in the east is the korabi zone interpreted as a microcontinent located further northeast within neotethys between the two is the mirdita zone dominated by two contrasting jurassic ophiolites the western type ophiolite and the eastern type ophiolite taking account of evidence from greece and former yugoslavia the following tectonic evolution is proposed from early mesozoic time onwards neotethys in albania existed as a northward continuation of the pindos oceanic basin in greece pindos mirdita ocean a korabi microcontinent was rifted off apulia in the early mid triassic followed by passive margin subsidence until late middle jurassic time a rifted slow spreading mor type ophiolite formed within the western pindos mirdita oceanic basin in late triassic early late jurassic time using present co ordinates the shkoder peje scutari pec lineament in the north of albania is interpreted as an important transform fault zone that influenced the regional tectonic evolution during the entire mesozoic early tertiary rift drift emplacement history of the pindos mirdita ocean taking account of evidence from the greek and former yugoslavia ophiolites the easterly albanian ophiolites formed within the pindos mirdita ocean above a westward dipping intra oceanic subduction zone in the early late jurassic metamorphic soles were formed during initial intra oceanic displacement ca 162 174 m y and underlying melanges originated as subduction accretion complexes the mor western type ophiolite evolved into the iat boninitic eastern type ophiolite after subduction began during tithonian berriasian time trench margin collision emplaced the ophiolites eastwards over the korabi margin coupled with redeposition of ophiolitic and continental margin material as exotic blocks debris flow deposits and turbidites these were emplaced onto the upper surface of the ophiolitic thrust sheet during the latest stages of emplacement onto the korabi microcontinent following collision in the east oceanic crust remained within a small remnant pindos mirdita oceanic basin passive conditions were restored in the mid late cretaceous with shallow water carbonate deposition on microcontinental units and both pelagic and redeposited carbonates in basinal settings from the maastrichtian onwards africa eurasia convergence resulted in large scale westward thrusting deforming the apulian foreland in oligo miocene time the suture zone was re activated in oligo miocene time as the albanie thassalie piggy back type basin in central and southern albania albania as a whole was rotated 45 clockwise as part of the western aegean arc in post eocene time coastal and offshore albania experienced strong subsidence after early miocene time forming the periadriatic basin including the tirana depression interpreted as a foredeep related to continuing regional convergence southern albania experienced extensional tectonics in plio quaternary time related to southward roll back of the aegean active margin

slow spreading accretion and mantle denudation in the mirdita ophiolite albania the mirdita ophiolite in albania occupies a n s corridor which escaped most alpine and cenozoic deformation possibly due to a thick ophiolitic basement the sheeted dike complex strikes ns and dips steeply indicating that the ridge was oriented parallel to the ns corridor and that the ophiolite has not been significantly tilted although differential motion between individual massifs cannot be excluded classically the western massifs have been considered lherzolitic and the eastern massifs harzburgitic detailed structural mapping reveals that the deep mantle section was harzburgitic and that the major differences between the two are restricted to the uppermost mantle and lower crustal section these are typically ophiolitic in the eastern massifs being composed of a thick dunitic transition zone rich in basaltic impregnations and chromite deposits overlain by a lower crust of layered gabbros in contrast in the western massifs the uppermost mantle is composed of highly strained to mylonitic lherzolites which originate from more depleted harzburgites by impregnation and tectonic dispersion of melt during deformation occurring at 1000 800 c layered gabbros are locally absent and the crust can be reduced to diabase dikes or sills and extrusives the diabase intrusions are locally sheared together with peridotites and metamorphosed to amphibolites the contrast between the eastern and western massifs is ascribed to successive episodes of magmatic and amagmatic spreading in a slow spreading environment the low t high strain deformation of the western massifs is localized in the dome shaped envelopes of these massifs this structure and even the present day topography of the western massifs evoke the turtleback domes described along the mid atlantic ridge mar and explained by mantle denudation tucholke et al 1998

beavers castoridae rodentia mammalia from the quaternary sites of the sierra de atapuerca in burgos spain abstract the eurasian beaver castor fiber is known from the pleistocene in europe although there are references to the presence of the genus castor since the miocene ca 10 ma beavers are present in the iberian peninsula since the pliocene though the first appearance of castor fiber took place in the early pleistocene levels of the localities of the sierra de atapuerca where the fossil beaver remains are found in the lower levels of sima del elefante and gran dolina early pleistocene galeria de las estatuas late pleistocene and portalon holocene the presence of fossil beavers suggests humid and mild climatic conditions in the early pleistocene levels of gran dolina and sima del elefante during the middle pleistocene although conditions for beavers seemed favourable they disappeared from atapuerca appearing again during the late pleistocene and the holocene

ophiolitic melange and flyschoidal sediments of the tithonian lower cretaceous in albania ophiolitic melange and flyschoidal sediments of the tithonian lower cretaceous age are widespread in the eastern albanides they lie transgressively or normally on top of the ophiolitic sequence through radiolarian cherts of the kimmeridgian tithonian age or on top of the carbonate sequence of the periphery of the ophiolites through middle liassic dogger malm pelagic limestones with manganese nodules and radiolarian cherts they are overlain by conglomerates or neritic limestones of the lower cretaceous age ophiolitic melange consists of ophiolitic conglobreccias often of homogenous composition serpentinite melange with a sedimentary serpentinite matrix or basaltic sedimentary tuffagglomerate less commonly they have a heterogeneous composition with small amounts of fine grained matrix and marls with calpionellids in other examples the ophiolitic melange contains heterogeneous exotic blocks including all the members of the ophiolite suite serpentinite ophicalcite gabbro plagiogranite diabase basalts dacites amphibolite sulphide and chromite ores as well as blocks of radiolarites limestones etc in the argillic matrix they are overlain by conglomerate sandstone marly flyschoidal deposits with abundant ophiolitic detritus and calpionellids these deposits are linked with tithonian lower cretaceous tectogenesis which led to the fragmentary uplift of ophiolites and partly of their sedimentary periphery and to the formation of the faulted topography the presence of the ophiolitic melange and flyschoidal sediments both over the ophiolites and the associated sedimentary rocks of their periphery indicate that the latter were not the basement of an ophiolite nappe during the late jurassic time

resource assessment of undiscovered seafloor massive sulfide deposits on an arctic mid ocean ridge application of grade and tonnage models abstract norway has started ongoing initiatives related to deep sea mining these include the evaluation of mineral resources within its sovereign territorial waters on the deep ocean floor of the arctic region i e the mohns ridge 71 73 n among the variety of possible seabed resources seafloor massive sulfides sms attract particular interest owing to the significant development potential and the general lack of knowledge of the sms deposits the present study aims at assessing mineral resources i e cu zn au and ag from a number of undiscovered sulfide deposits with the help of a revised model for mafic hosted volcanogenic massive sulfide vms deposits that adequately corresponds to geological settings of slow spreading ridges application of the model requires a priori knowledge of the seafloor terrain to depict favorable geologic environments for the occurrence of sms deposits in such context estimates are conducted for the easily accessible volcanically active parts of the ridge where 11 undiscovered deposits are expected in these areas total metal endowments are calculated to be on average 447 000 tonnes using a monte carlo simulation that combines the probabilistic estimates of number of undiscovered deposits with the grade and tonnage models estimates of in place metal resources are generated in cumulative distribution form to present expected amount of undiscovered metals at 90 confidence intervals

environmental change across the early middle pleistocene transition small mammalian evidence from the trinchera dolina cave atapuerca spain t he sites of atapuerca are well known for their hominin bearing localities of early to middle pleistocene age trinchera dolina yields western europe s oldest fossil hominin the 850 ka homo antecessor and at sima de los huesos there occurs the best collection of the middle pleistocene hominin homo heidelbergensis however small mammals rodentia insectivora chiroptera and lagomorpha represent the largest number of species and greatest fossil abundance in the deposits of the atapuerca cave complex the small mammals are grouped by habitat catego ries but because the ecology of mammals is complex we base our study on the evolution of these categories throughout the sequence the assemblage distribution at the trinchera dolina site reflects landscape and environmental changes during the past million years shifts between wood land open land and moorland are indicated by the relative abundance of species based on diagnos tic elements such as first lower molars these data are combined with the distribution of large mammals pollen sediments and geological context of the trinchera dolina site from this interdis ciplinary approach we conclude that the first hominins from western europe homo antecessor lived during a warm wet and wooded interval probably corresponding to marine isotope stages 21 to 19 the transition from early to middle pleistocene at atapuerca is characterized by palaeoenvi ronmental changes recorded between levels td5 6 and td8 10 respectively the general opening of the landscape at the beginning of the middle pleistocene could have favoured the dispersal of hominins homo heidelbergensis across western europe

seismic sensor array for monitoring an avalanche start zone design deployment and preliminary results in snow acoustic emissions originate from the breaking of bonds between snow crystals and the formation of cracks previous research has shown that acoustic signals emanate from a natural snowpack the relation between these signals and the stability of the snowpack has thus far remained elusive studies on other hazardous gravitational processes suggest that damage accumulation precedes major failure if increased cracking activity could be detected in snow this might be used for avalanche prediction we report on the development of a seismic sensor array to continuously monitor acoustic emissions in an avalanche start zone during three winters over 1400 sensor days of continuous acoustic data were collected with the aid of automatic cameras and a microphone the main types of background noise were identified seismic signals generated by avalanches were also identified spectrograms from seismic signals generated by avalanches exhibit a unique triangular shape unlike any source of background noise suggesting that automatic detection and classification of events is possible furthermore discriminating between loose snow and snow slab avalanches is possible thus far we have not identified precursor events for natural dry snow slab avalanche release detailed investigation of one dry snow slab avalanche showed that signals observed prior to the release originated from background noise or small loose snow avalanches

tectonic development of the vardar ocean and its margins evidence from the republic of macedonia and greek macedonia abstract the tectonic development of the northeast margin of the korabi pelagonian continent and the adjacent vardar ocean is discussed based on study of nine traverses across the former northeastern margin of the korabi pelagonian continent represented by the west vardar subzone in the republic of macedonia a detailed correlation of units is also made across the international border with greece coupled with regional comparisons precambrian palaeozoic units were metamorphosed and intruded by granitic rocks followed by mid triassic rifting and the construction of a carbonate platform bordering a late triassic early jurassic ocean neritic deposition was followed by late jurassic syn or pre early tithonian subsidence with radiolarian and then terrigenous turbidite sedimentation overlying ophiolitic rocks are characterised by a relatively thin 200 km n s sheet of sheared blocky serpentinite mainly mantle harzburgite associated with ophiolite derived debris flows the emplaced ophiolitic rocks were subaerially weathered to form local fe ni accumulations following marine transgression a shallow water carbonate siliciclastic deposits including coralgal reefs accumulated during late tithonian early cretaceous after a hiatus mixed terrigenous carbonate gravity flows accumulated in deep water during the late cretaceous the vardar ocean opened during the late triassic early jurassic separating the korabi pelagonian and serbo macedonian continents northeastward subduction created a late jurassic magmatic arc along the southern margin of the serbo macedonian continent while future ophiolites formed by supra subduction zone spreading within the vardar ocean these ophiolites were emplaced in response to collision of the subduction trench with the korabi pelagonian continent the pre mesozoic basement detached and subducted undergoing high pressure low temperature metamorphism during the late jurassic tithonian followed by amphibolite greenschist facies metamorphism and exhumation prior to the late cretaceous a much reduced vardar ocean survived into the late cretaceous until this finally closed during the latest cretaceous early cenozoic triggering continental collision and thick skinned folding thrusting of the pelagonian vardar and serbo macedonian zones towards the w sw

geodynamic models of convergent margin tectonics transition from rifted margin to overthrust belt and consequences for foreland basin development a quantitative geodynamic model for overthrusting of a passive continental margin during attempted continental subduction demonstrates the mechanical and thermal coupling between overthrust loads the lithosphere and the associated foreland basin the model treats the lithosphere as a two dimensional nonuniform elastic plate whose strength is controlled thermally the thermal and flexural evolution of a margin is followed from initial rifting and passive margin development through overthrusting and foreland basin deposition to postdeformational erosion our models indicate the following 1 foreland basin geometry is relatively insensitive to the age of the preexisting passive margin prior to overthrusting sensitivity decreases the farther the overthrust load is empl ced onto the craton 2 foreland basin depth is strongly influenced by the size of the overthrust load maximum depths in excess of 10 km 6 mi can occur given overthrust topography similar to the present day himalayas 3 a few tens of kilometers of postdeformational erosion can occur across topographically high orogenic belts before moderate topography is attained very little of this eroded material is deposited in the foreland basin most must bypass the basin because it also is subjected to erosion and associated flexural uplift 4 thick overthrusts as interpreted from cocorp profiling are consistent with low topographic expression because they were emplaced on preexisting oceanic and stretched continental lithosphere

emplacement of the jurassic mirdita ophiolites southern albania evidence from associated clastic and carbonate sediments sedimentology can shed light on the emplacement of oceanic lithosphere i e ophiolites onto continental crust and post emplacement settings an example chosen here is the well exposed jurassic mirdita ophiolite in southern albania successions studied in five different ophiolitic massifs voskopoja luniku shpati rehove and morava document variable depositional processes and palaeoenvironments in the light of evidence from comparable settings elsewhere e g n albania n greece ophiolitic extrusive rocks pillow basalts and lava breccias locally retain an intact cover of oceanic radiolarian chert in the shpati massif elsewhere ophiolite derived clastics typically overlie basaltic extrusives or ultramafic rocks directly the oldest dated sediments are calpionellid and ammonite bearing pelagic carbonates of latest jurassic berrasian age similar calpionellid limestones elsewhere n albania n greece post date the regional ophiolite emplacement at one locality in s albania voskopoja calpionellid limestones are gradationally underlain by thick ophiolite derived breccias containing both ultramafic and mafic clasts that were derived by mass wasting of subaqueous fault scarps during or soon after the latest stages of ophiolite emplacement an intercalation of serpentinite rich debris flows at this locality is indicative of mobilisation of hydrated oceanic ultramafic rocks some of the ophiolite derived conglomerates e g shpati massif include well rounded serpentinite and basalt clasts suggestive of a high energy shallow water origin the berriasian pelagic limestones at voskopoja experienced reworking and slumping probably related to shallowing and a switch to neritic deposition mixed ophiolite derived clastic and neritic carbonate sediments accumulated later during the early cretaceous mainly barremian aptian in variable deltaic lagoonal and shallow marine settings these sediments were influenced by local tectonics or eustatic sea level change terrigenous sediment gradually encroached from neighbouring landmasses as the ophiolite was faulted or eroded an aptian transgression was followed by regression creating a local unconformity e g at boboshtica a turonian marine transgression initiated widespread upper cretaceous shelf carbonate deposition in the regional context the southern albania ophiolites appear to have been rapidly emplaced onto a continental margin in a subaqueous setting during the late jurassic late oxfordian late tithonian this was followed by gradual emergence probably in response to thinning of the ophiolite by erosion and or exhumation the sedimentary cover of the south albanian ophiolites is consistent with rapid relatively short distance emplacement of a regional scale ophiolite over a local pelagonian korabi microcontinent

stratigraphic units overlying the zambales ophiolite complex zoc in luzon philippines tectonostratigraphic significance and regional implications abstract the zambales ophiolite complex zoc on the island of luzon philippines is one of the most well studied crust mantle sequences in the region several massifs comprise the zoc one of which is the coto block overlain by clastic sedimentary units previously dated as eocene geochronologic studies from diabase granodiorites and other late stage magmatic products similarly yielded the same age succeeding tectonic models have therefore all been grounded on the assumption that the entire zoc is eocene recent investigations however revealed the presence of chert blocks within the early to middle miocene clastic formation overlying the acoje block in the northern part of the ophiolite complex radiolarians extracted from the cherts yielded a stratigraphic range that suggests a late jurassic to early cretaceous age the recognition of a much older age than previously reported of the zoc warrants a re examination of its actual distribution and genesis correlating with other similarly aged ophiolites we suggest defining a western mesozoic ophiolite belt largely extending from the west central portion of the archipelago to the northeastern tip of luzon island tentatively we attribute the mesozoic ophiolitic and associated rocks in western luzon to an arc continent collision involving the philippine mobile belt and the palawan microcontinental block in addition differences in the clastic compositions of the cenozoic sedimentary formations provide material not only for deciphering the zoc s unroofing history but also for constraining the timing of province linkage the intermittent appearance of lithic fragments and detrital minerals from the ophiolite in the units of the middle miocene candelaria limestone and the late miocene to early pliocene sta cruz formation indicates significant but geographically variable contributions from the ophiolite complex in the northern zambales range the sta cruz formation caps the coto block and the acoje block of the zoc providing a minimum age for their amalgamation

fossil bat assemblages as palaeoenvironmental and palaeoclimatic indicators a case study in the lower to middle pleistocene gran dolina sequence of sierra de atapuerca northern spain abstract bat remains occur in low numbers in pleistocene cave assemblages compared to other small vertebrates and therefore are rarely used as palaeoenvironmental or palaeoclimatic indicators in this study we address the correlation between bat palaeocommunity dynamics and climate and environmental factors by analysing the fossil bat record throughout the lower to middle pleistocene gran dolina sequence of atapuerca spain we show that the palaeodiversity and palaeoclimatic markers employed in our bats based approach provide coherent results with other palaeoclimatic indicators we report a general impoverishment of bat palaeocommunities towards the upper section of the sequence that correlates with evidence of climate deterioration based on palynological analysis and data from other small vertebrates groups we also find that the occupational pattern of the dominant bat species myotis myotis changes at the top of the sequence from a probable all year occupation to a seasonal winter use of the cave which could be related to the onset of human occupation of the cave site finally we note that while the habitat weighting analysis of bat assemblages is correlated to independent palaeoenvironmental proxies such bats based approaches show an overrepresentation of woodland habitats in comparison to other small vertebrates indicators

metamorphic soles from the albanian ophiolites petrology 40ar 39ar geochronology and geodynamic evolution in the eastern mediterranean region the albanian ophiolites are remnants of one branch of the tethyan oceanic basin obducted on carbonate margins during the mesozoic pressure temperature time and structural data in the metamorphic soles of these ophiolites place new constraints on the closure of this basin and the emplacement history of oceanic rocks the petrological and structural work documents an apparently inverted metamorphic gradient with granulite facies at the top decreasing downward through amphibolite then greenschist facies until unmetamorphosed rocks thermobarometry indicates that the granulite facies formed at peak temperatures of 800 860 c for pressures close to 1 gpa these conditions point to the subduction of the ophiolites beneath young oceanic lithosphere to a depth of 30 40 km a large set of 40ar 39ar data has been obtained on the metamorphic soles and some ophiolite intrusives using single grains and bulk mineral populations ages range from 160 to 174 ma corresponding to the middle jurassic bajocian bathonian within the same sole the convergence of results using single grains and mineral populations of amphibole and muscovite and the lack of internal age gradient within muscovite are interpreted to result from fast cooling of metamorphic soles the main result documented by this study is a systematic younging of metamorphic sole ages from south to north with a difference of 14 ma along the 140 km length of the belt the age of igneous rocks such as plagiogranites and mafic dikes in the ophiolites is equivalent to that of metamorphic soles which indicates that the ophiolite was still hot and young at the time of metamorphic sole formation the emplacement of the albanian ophiolites is the consequence of a complex tectonic evolution continental rifting slow mid ocean spreading followed by west dipping intraoceanic subduction initiated at the ridge axis symmetric intraoceanic thrusting with opposite vergence and at last emplacement onto the continental margin the geochronological and stratigraphic data suggest that this evolution lasted only a few million years moreover they indicate that this evolution stopped earlier to the south with the closure of a narrow basin than to the north where the basin was wider due to faster oceanic spreading

oceanic core complexes and ancient oceanic lithosphere insights from iapetan and tethyan ophiolites canada and albania abstract oceanic ridges are extensional environments characterized by brittle to ductile normal faulting and episodic magma supply studies in modern oceanic settings suggest that the interplay of low angle detachments and high angle normal faults locally lead to the exhumation of lower crust and upper mantle peridotites to the seafloor as oceanic core complexes along the mid atlantic ridge core complexes typically occur in inside corners of intersections between the ridge axis and major transform faults the core complexes were exhumed by movement along long lived detachment faults that extend for 10s of km and that are crosscut by high angle normal faults oriented parallel to the rift axis ridge segments with abundant detachments would be characterized by lithosphere having little or no upper crust similar features in ophiolites may also reflect the dominance of amagmatic extension this contribution presents two examples of fossilized oceanic core complexes preserved in the canadian appalachian and albanian dinaride ophiolite belts in the canadian appalachians the southern quebec ophiolites experienced two paleozoic orogenies after their obduction onto the laurentian margin although locally obscured by tectonic fabrics and structures the original relationships between the ophiolitic mantle the overlying plutonic section and onlapping ordovician siliciclastic rocks are well preserved in the thetford mines ophiolite which also shows similarities with lithological and structural features of the mirdita ophiolite where conformable contacts between the sedimentary cover sequence debris flows and flysch deposits and the mantle and crustal sections are superbly exposed the jurassic mirdita ophiolite in albania underlies ca 4000 km2 and was only slightly affected by the tertiary alpine orogeny of eastern europe well exposed sections of the ophiolite suggest that the oceanic mantle was exhumed prior to obduction and locally records the formation of an oceanic core complex mafic cumulates of the mirdita ophiolite have been totally excised in places and exhumation related shear zones are preserved in the krabbi puka massif the shear zones are manifested both within the mantle and at the contact with overlying basalts the ophiolitic sedimentary sequence was deposited on basalts sheeted dykes or gabbros and typically consists of debris flows intercalated with and overlain by slumped oceanic sedimentary rocks the lithological and structural characteristics of both the thetford mines and the mirdita ophiolites are consistent with extensional tectonism crustal excision and lower crust upper mantle exhumation during formation both ophiolites are believed to have originated during asymmetrical oceanic extension in a suprasubduction zone setting with preservation of the upper plate lower plate segments during obduction

the gran dolina site lower to middle pleistocene atapuerca burgos spain new palaeoenvironmental data based on the distribution of small mammals new palaeoenvironmental data are reported after analysing the distribution of micromammals orders rodentia insectivora chiroptera and lagomorpha in the 11 stratigraphical levels at the gran dolina site td1 td11 early to middle pleistocene atapuerca spain a continental dry and cold climate is inferred at the beginning of the succession td3 to lower td5 the fauna in the upper td5 and in td6 reflects a complex interglacial period with fluctuations in the degree of relative humidity in the lower part of td8 the presence of microtus aff ratticepoides indicates a relatively cold period finally data from upper levels td8b td10 td11 reflect another interglacial period with slight oscillations in relative moisture the different levels at gran dolina are also correlated with oxygen isotope stages ois td3 td4 and td5 may be correlated with ois 22 td6 is correlated with ois 21 lower td8 td8a is correlated with ois 18 upper td8 td8b is correlated with ois 13 or 15 td10 and td11 are correlated with ois 9 or 11

dry slab avalanche shear fracture properties from field measurements 1 dry slab avalanches release by propagation of shear fractures in a thin planar weak layer underneath a cohesive stronger slab this implies that a balance between shear fracture toughness and the shear fracture stress intensity factor fundamentally determines snow slab stability conventionally fracture toughness is a material property and for most materials emphasis is on tensile fracture since most materials fail first in tension however for the snow slab the weak layer fractures first and field measurements show that the slab material is always stronger than the weak layer snow slabs in nature vary with respect to mechanical properties and other characteristics so the concept of fracture toughness as a material property has no relevance when it is calculated for different avalanches in this paper field measurements collected from hundreds of snow slabs are combined with the cohesive crack model to yield estimates for the mode ii shear fracture toughness kiic the results suggest that the snow slab has extremely low fracture toughness with variations in nature over more than two orders of magnitude the nominal weak layer shear strength nu has a power law relationship with respect to the fundamental scaling parameter the slab thickness d model results also imply that kiic has power law scaling with respect to d it is also shown that kiic follows a log normal probability density function this implies a multifractal character by considering the moments q of shear fracture toughness scaled with d positive multifractal dimensions are suggested for q up to approximately 2

snow avalanche formation 1 snow avalanches are a major natural hazard endangering human life and infrastructure in mountainous areas throughout the world in many countries with seasonally snow covered mountains avalanche forecasting services reliably warn the public by issuing occurrence probabilities for a certain region however at present a single avalanche event cannot be predicted in time and space much about the release process remains unknown mainly because of the highly variable layered character of the snowpack a highly porous material that exists close to its melting point the complex interaction between terrain snowpack and meteorological conditions leading to avalanche release is commonly described as avalanche formation it is relevant to hazard mapping and essential to short term forecasting which involves weighting many contributory factors alternatively the release process can be studied and modeled this approach relies heavily on snow mechanics and snow properties including texture while the effect of meteorological conditions or changes on the deformational behavior of snow is known in qualitative or semiquantitative manner the knowledge of the quantitative relation between snow texture and mechanical properties is limited but promising developments are under way fracture mechanical models have been applied to explain the fracture propagation and micromechanical models including the two competing processes damage and sintering have been applied to explain snow failure there are knowledge gaps between the sequence of processes that lead to the release of the snow slab snow deformation and failure damage accumulation fracture initiation and fracture propagation simultaneously the spatial variability that affects damage fracture initiation and fracture propagation has to be considered this review focuses on dry snow slab avalanches and shows that dealing with a highly porous media close to its melting point and processes covering several orders of scale from the size of a bond between snow grains to the size of a mountain slope will continue to be very challenging

fracture mechanical models of dry slab avalanche release experimental evidence shows that snow is a pressure sensitive dilatant strain softening material in slow constant rate shear deformation when strain softening initiates in a weak layer underneath a snow slab avalanche release is hypothesized to be possible with or without additional loading specifically two cases are discussed 1 a shear crack like disturbance can initiate after formation of a slip surface in the weak layer and traverse the layer by a self propagating progressive failure with or even without loading and 2 a self propagating shear instability can develop when a region of the weak layer is driven past peak shear strength by loading for these cases the implied fracture sequence fracture geometry time scale of release and temperature effects are discussed and shown to be consistent with the known facts of dry slab avalanche release

a numerical model to simulate snow cover stratigraphy for operational avalanche forecasting laws of snow metamorphism have been introduced in a numerical model which simulates the evolution of temperature density and liquid water profiles of snow cover as a function of weather conditions to establish these laws the authors have summarized previous studies on temperature gradient and on wet snow metamorphism and they have also conducted metamorphism experiments on dry or wet fresh snow samples an original formalism was developed to allow a description of snow with parameters evolving continuously throughout time the introduction of laws of metamorphism has improved significantly the derivation of the settlement of internal layers and of snow covered albedo which depend on the simulated stratigraphy i e the type and size of snow grains of different layers of the snow cover the model was tested during a whole winter season without any re initialization comparison between the simulated characteristics of the snow cover and the observations made in the field are described in detail the model proved itself to be very efficient in simulating accurately the evolution of the snow cover stratigraphy throughout the whole winter season

the jurassic south albanian ophiolites mor vs ssz type ophiolites abstract within the western belt of the southern albanian ophiolites the voskopoja ophiolite consists of three subunits voskopoja morava and rehove these are predominantly lherzolites with minor harzburgites and dunites in the mantle section above come ultramafic and mafic cumulates including wehrlites troctolites and olivine gabbros gabbronorites are restricted to the morava subunit isotropic clinopyroxene gabbros extrusives and sediments are present only in rehove and voskopoja the volcanic section is dominated by basaltic breccias including megablocks with sheeted dykes pillow lavas and isolated dykes the basaltic breccias grade upwards into sandstones in turn interlayered with argillites and cherts of jurassic age the basalts are predominantly clinopyroxene plagioclase basalts either aphyric or plagioclase phyric geochemically they are divided into four groups 1 an intermediate ti and zr group with low ni hereafter called low ni group 2 an intermediate ti zr group with high ni hereafter called high ni group 3 a high ti zr group and 4 a low ti zr group the high ni content in group 2 is interpreted as originating from olivine and spinel xenocrysts apart from the high ni content groups 1 and 2 are comparable with the volcanics of the low to high ti intermediate ophiolites by contrast group 3 is more comparable to the high ti ophiolitic extrusives in the western ophiolite belt of northern albania group 4 consists ssz type basalts and is widespread in the volcanics of the eastern ophiolite belt comparison of the ultramafic mafic cumulates and the basaltic volcanics with those in the northern part of the western belt in albania and the pindos ophiolite indicates that there is a systematic variation in petrography and geochemistry from north to south in the western belt with an increasingly distinct ssz signature towards the south ultramafic and mafic cumulates as well as basalts from the shebenik massif in the eastern belt are similar to those of voskopoja implying a genetic relationship

the early middle pleistocene palaeoenvironmental change based on the squamate reptile and amphibian proxies at the gran dolina site atapuerca spain abstract although still ongoing the archaeological and palaeontological excavations in the gran dolina cave sierra de atapuerca burgos every year since 1976 have already revealed a long culturally and palaeontologically rich sequence dated by biostratigraphy esr u series and the palaeomagnetic record at between roughly 1 my and 250 ky gran dolina has one of the longest and most continuous vertical profiles the section 19 m thick divided into 11 stratigraphic levels represents a time span of nearly 700 000 years the gran dolina sequence was partially excavated during a preliminary evaluation of its archaeological and palaeontological richness this excavation known as the gran dolina sondeo south lasted from 1993 to 1999 hominin remains were unearthed in 1994 from level 6 of gran dolina and level 6 was dated to somewhat more than 780 ky based on palaeomagnetic and microfaunal evidence making these the oldest known hominins in europe given the importance of this discovery every effort is being made to reconstruct the landscapes where these hominins once thrived the gran dolina sondeo south tds has furnished a great number of microvertebrate remains and of these around 40 000 bones are attributed to amphibians and squamates the faunal list of the squamates and amphibians of the tds comprises at least 22 species a diversity similar to what exists nowadays in spain triturus sp alytes obstetricans pelobates cultripes pelodytes punctatus bufo bufo bufo calamita hyla arborea rana temporaria rana cf dalmatina rana cf iberica pelophylax ridibunda sp blanus cinereus lacerta s l small sized indeterminate lacertids anguis fragilis natrix natrix natrix maura coronella austriaca coronella cf girondica rhinechis scalaris vipera cf aspis and vipera cf latasti these ectotherm vertebrates show variations in their taxonomic diversity throughout the sequence although they do not differ specifically from the extant herpetofauna of the iberian peninsula they do so in the composition of their taxonomic assemblage when the squamates and amphibians of tds are grouped by habitat categories the habitat weightings method and studied in terms of their vertical evolution throughout the sequence it is possible to follow environmental changes across the early middle pleistocene transition results from the squamate and amphibian studies indicate that the landscape had open habitats in the vicinity of the atapuerca caves throughout the sequence with wet points in the surrounding area open dry microhabitats were more developed during warm periods whereas during cold periods the environment was slightly more humid and wooded these results are compared with studies in small mammals pollen analysis and geomorphology giving a scenario for the palaeoclimatic and palaeoenvironmental changes that occurred during the early to middle pleistocene boundary in atapuerca and hence a scenario for the hominins that once lived in the sierra de atapuerca

the spatial variability of snow resistance on potential avalanche slopes since snow avalanches are believed to release from zones of localized weakness knowledge of snow strength patterns is important for determining slope stability and for applying effective avalanche control measures in this study the spatial variability of snow resistance an index of snow strength and depth were measured and compared with terrain features on two inclined slopes a refined instrument allowed the strength of an entire snow slab to be characterized in a short time the spatial pattern of trees appeared to affect the pattern of snow depth at one site where a significant linear relationship was found between snow depth and average snow resistance these results suggest that localized snow depth variations may be important in snow strength genesis although a linear relationship existed at that site additional factors may be critically relevant a second site with more complex terrain features and less localized wind drifting did not show a linear relationship between depth and average resistance instead complex patterns of resistance demonstrated that many factors contribute to snow resistance in particular the snow overlying rocks was found to have significantly weaker resistance than that in adjacent areas not over rocks

one million years of cultural evolution in a stable environment at atapuerca burgos spain abstract the present paper analyses the evidence provided by three sites sima del elefante gran dolina and galeria located in the trinchera del ferrocarril of the sierra de atapuerca these three sites are cave infillings that contain sediments deposited from approximately 1 2 ma to 200 kyr pollen herpetofauna and small and large mammal remains are used as proxies to obtain a general picture of the environmental changes that occurred at the sierra de atapuerca throughout the one million year period represented at these sites similarly cultural changes are tracked analyzing the evidence of human behavior obtained from the study of several bone and lithic assemblages from these three sites at least three periods with different cultural features involving technology subsistence and behavior are determined from the available evidence the first two periods correspond to the mode 1 technology and homo antecessor the first is dated around 1 2 to 1 0 ma and reflects opportunistic behavior both in technology and subsistence the second period is around 800 kyr bp mode 1 technology is still maintained but subsistence strategies include systematic hunting and the use of base camps the third period is dated between 500 ka and 200 ka and corresponds to the mode 2 technology and the acquisition of directional hunting and other organizational strategies by homo heidelbergensis a transition from mode 2 to mode 3 seems to appear at the end of this time range and may reflect the early phases of a fourth cultural change with regard to the environment our main conclusion is that there was an absence of extremely harsh conditions at atapuerca throughout this time period the presence of mediterranean taxa was constant and the dominant landscape was a savannah like open environment probably with small forest patches an alternation of mediterranean and mesic species as the dominant component of the tree storey was induced by the climatic cycles and steppes spread across the landscape during the drier periods in any case it is not possible to establish clear cut off points separating entirely different environmental episodes our results show no evidence of any relationship between environmental change and cultural change at the sierra de atapuerca

tectonic sedimentary evolution of the western margin of the mesozoic vardar ocean evidence from the pelagonian and almopias zones northern greece

heterogeneous mantle complex crustal processes and obduction kinematics in a unified pindos vourinos ophiolitic slab northern greece

approximate estimates of fracture speeds for dry slab avalanches 1 dry slab avalanches release by propagating shear fractures it has been suggested that slab wave or fracture speed on horizontal terrain is consistent with the propagation of a flexural wave in the slab in this note an alternate proposal is made namely it is proposed that the fracture speed is consistent with dynamic crack propagation speeds from other materials the theory is compared with an in situ measurement of speed associated with shear fracture propagation in a weak snow pack layer sensed by geophones placed on the surface of a horizontal snow pack the theory is shown to be consistent with the mechanical properties of alpine snow and known characteristics of slab avalanche release

spatial patterns of surface hoar properties and incoming radiation on an inclined forest opening avalanche hazard evaluation relies in part on representative snowpack stability obser vations thus understanding the spatial patterns of snowpack instabilities and their environmental determinants is crucial this case study integrates intensive field observations with spatial modeling to identify associations between incoming radiation surface hoar development and its subsequent shear strength across an inclined forest opening we examined a buried surface hoar layer in southwest montana usa over five sampling days collecting 824 snowmicropen resistance profiles and performing 352 shear frame tests spatial models of incoming long and shortwave radiation were generated for the surface hoar formation period using modeled hemispheric sky visibility physically based parameters and the bird clear sky radiation model in a geographic information system before burial the surface hoar persisted despite moderate winds and relatively high air temperatures the buried surface hoar layer thickness varied between 3 and 21 mm within a distance of 30 m modeled incoming radiation explained spatial variations in layer thickness and shear strength in areas exposed to large amounts of radiation the surface hoar layer was strong and thin while areas with limited incoming radiation due to high sky visibility and shading possessed a thicker surface hoar layer that sheared more easily this demonstrates the usefulness of microclimate modeling for slope scale avalanche hazard evaluation we also identify that over the 3 week sample period strengthening occurred without thinning of the surface hoar layer

genesis of the batinah melange above the semail ophiolite oman abstract the batinah melange which overlies the late cretaceous semail ophiolite in the northern oman mountains comprises mostly sedimentary rocks of deep water facies alkalic lavas and intrusives all of continental margin affinities together with smaller volumes of semail ophiolitic and metamorphic rocks four intergradational textural types of melange can be recognized sheet melange has large 1 km intact sheets either with little intervening matrix or set in other melange types and with an organised sheet orientation fabric slab melange is finer textured 100 m and more disrupted block melange has smaller m blocks with some matrix and a weak to random block fabric clast melange is matrix supported rudite with a weak depositional clast fabric structural relationships particularly the absence of tectonic fabrics the decreasing strength of fragment fabrics with increasing fragmentation and the abundance of brittle fragmentation suggest that these melange types formed by either gravity driven sedimentary processes or superficial sliding or thrusting of individual rock slabs in the slab melange long sequences can be pieced together passing up from upper triassic mafic sub marine extrusives and sediments into radiolarian cherts hemipelagic and redeposited limestones and terminating in non calcareous radiolarities with mn deposits of early cretaceous age mafic sills are numerous these sequences can be matched with sub ophiolite rocks now exposed in fault corridors through the semail these sequences become progressively disrupted upwards in the corridors and can be traced continuously into overlying melange which then thins away from the corridors we argue that during late cretaceous emplacement over the arabian margin active fault corridors split the semail slab and acted as conduits up which sub ophiolite rocks were supplied to the ophiolite surface there the rocks were redisributed by superficial processes

a porosity based biot model for acoustic waves in snow phase velocities and attenuation in snow cannot be explained by the widely used elastic or viscoelastic models for acoustic wave propagation instead biot s model of wave propagation in porous materials should be used however the application of biot s model is complicated by the large property space of the underlying porous material here constant properties for ice and air and empirical relationships are used to estimate unknown porous properties from snow porosity using this set of equations phase velocities and plane wave attenuation of shear and compressional waves are predicted as functions of porosity or density for light snow the peculiarity was found that the velocity of the first compressional wave is lower than that of the second compressional wave that is commonly referred to as the slow wave the reversal of the velocities comes with an increase of attenuation for the first compressional wave this is in line with the common observation that sound is strongly absorbed in light snow the results have important implications for the use of acoustic waves to evaluate snow properties and to numerically simulate wave propagation in snow