morphotectonic structure of the western part of the north aegean basin based on swath bathymetry abstract the morphotectonic structure of the north aegean basin is studied on the basis of a new detailed swath bathymetric survey the resulting bathymetric map is presented in reduction with 20 m isobaths the slope analysis gives an accurate scheme of the geometry of the basin and distinction of several sub basins approximately 20 the overall basin geometry is a rectangular tetrahedron shaped by the major slope discontinuity separating the continental platform from the continental slope the area distribution with depth shows a maximum at depths between 300 and 450 m along the sub horizontal edge of the continental platform and at depths between 1000 and 1200 m at the basinal areas of the sub basins the separation of the western part of the north aegean basin from the eastern part saros bay is very clear in the area between limnos and thasos with a maximum depth of 490 m the 3 2 of the basin area is characterized by slope values 20 which correspond to active fault zones their trend is ne sw n46 and nw se n136 some secondary e w faults are also present within the basin with morphological expression only on the orientation of slopes

on the hellenic subduction zone and the geodynamic evolution of crete since the late middle miocene abstract in recent syntheses of the geodynamic evolution of the aegean area the hellenic subduction zone and in particular its initiation plays a central role two basic aspects of the recent comprehensive model put forward by le pichon angelier and co workers are a initiation of subduction along the hellenic arc is inferred to have taken place approximately 13 ma ago whereas several others have suggested approximately 5 ma and b migration of the trench system to the south southwest giving rise to an extensional regime in the back arc region which led to general subsidence and formation of the present day aegean sea new data on the structure of the upper mantle underneath the aegean area indicate that the former aspect requires modification the seismic velocity structure indicating a northward dipping slab down to a depth of at least 600 km and the depth distribution of earthquake hypocenters can not be reconciled with straightforward initiation of subduction approximately 13 ma ago estimates of about 5 ma for the time of initiation of the present subduction zone are even more difficult to reconcile assuming 400 km as an upper bound for the effect of stretching of the aegean sea and of other processes contributing to the separation of crete from the eurasian mainland we arrive at an age for the hellenic subduction zone of at least 26 ma as to aspect b geological data of crete lend strong support to the idea that on crete compressional tectonics is of much greater importance than current models imply combining geophysical and geological data we propose a modification of the tectonic evolution for the cretan segment of the hellenic arc whereas the basic process of extension caused by a migrating trench system roll back in a land locked basin remains a very useful and sound concept the tectonics of the margins of a region subject to stretching in this case crete may be more complicated than hitherto thought in our model the documented fragmentation of crete into several basins which started about 12 ma ago is not attributed to initiation of subduction but to inception of the roll back process compressional tectonics on crete is taken to be associated with deformation of the crust resulting from the overall tensional stress regime

late quaternary evolution of the northern aegean shelf abstract a dense network of 3 5 khz and uniboom seismic profiles revealed the geological evolution of the ierissos alexandroupolis shelf area of the northern aegean during the latest sea level rise near the end of the pleistocene ca 14 000 yr b p the sea was at about 120 m and almost 5300 km2 of shelf was exposed to subaerial erosion two permanet lakes existed in the ierissos and kavalla gulfs as well as a number of ephemeral lakes scattered throughout the rest of the area kavalla gulf was drained by the nestos river which joined the strymon river at the outer strymonikos plateau on the flat samothraki plateau were dune fields marshes and a number of minor seasonal rivers while the evros river flowed east of the plateau by ca 13 000 yr b p the sea had risen to 70 m and covered 30 of the previously exposed shelf the lakes at ierissos and strymonikos gulfs were shallower and the sea approached to within about 5 km of them kavalla gulf and the adjacent eastern strymonikos plateau lay 10 m above sea level while the sea intruded along river mouths at the samothraki plateau during this transgression of the sea river bed gravels and sands were covered by silts and clays at the pleistocene holocene transition ca 10 500 yr b p the sea lay at about 50 m and in areas of steep slope the coast was close to its present position at kavalla gulf the sea advanced along the paleochannel of the nestos river and the island of samothraki was separated from the mainland by ca 7500 yr b p the sea was only 15 m below its present level and the northeastern aegean shelf assumed nearly its present morphology the nestos river changed course to the east and thassos island was separated from the mainland coarse sediment formed wedges nearshore whereas fine grained sediments were distributed widely by current action in many areas relict sediments are present

controls on the siting and style of volcanogenic massive sulphide deposits abstract volcanogenic massive sulphide vms deposits form in subaqueous environments from circulating hydrothermal fluids heated by volcanic activity these deposits form as sulphide mounds stratiform exhalative and or replacive bodies and commonly have stockwork vein mineralization in their immediate footwall these various styles are essentially facies of mineralization each one being the product of a particular set of conditions that control the ore forming processes and the consequent geometry and architecture style of the deposits these controls include the physical and or chemical nature of the host rocks the temperature and composition of the hydrothermal fluids and the redox state of the depositional environment the style of exhalative deposits is controlled by the salinity of the vented fluids and the redox state at the seafloor hydrothermal fluids with salinities less than twice that of seawater that vented into open oxic oceanic environments typically formed small mound and chimney complexes unless they were rapidly covered by sediments or volcanic rocks the massive sulphides were rapidly oxidized and partly dissolved by seawater in contrast stratiform sheet like deposits are typically formed in anoxic bottom waters anoxic marine conditions were periodically of global extent particularly prior to 2 4 ga or of a regional nature local anoxic conditions can also be self induced by the exhalation of saline and reducing hydrothermal fluids that ponded in bathymetric depressions such as second or third order basins to form a brine pool these exhalative systems may have been initiated as chimney vent complexes and subsequently overlain by stratiform sulphides formed under the self induced anoxic conditions deposits formed in anoxic environments can be significantly larger than those in oxic settings and this is attributed to several factors that include longer lived hydrothermal circulation more efficient sulphide precipitation and reduced or inhibited oxidation thereof replacement of volcanic and sedimentary strata by sulphide typically occurs within the feeder zones beneath the exhalative mineralization however successions with abundant porous permeable and or reactive rocks such as glassy and or pumiceous volcaniclastic rocks and in some cases limestone favoured the development of large replacive deposits that may have had little surficial expression on the sea floor vms deposits at spreading centres within oceanic crust formed almost exclusively as mounds most of them have not been preserved likely due to oxidation of the sulphides in the prevailing oxic environment and or destruction of oceanic crust during subsequent subduction intra continental rifts arc rifts and back arc rifts commonly have more complexity in their structure and facies architecture and environments and can host all styles of vms mineralization in these settings early extension favoured the formation of restricted basins with ideal conditions for the onset of hydrothermal activity and development of anoxic bottom waters whereas in mature rifts the conditions were less conducive for the formation of regionally extensive anoxic environments formation of replacive deposits was permissible in all settings with porous or reactive subsea floor strata replacive mineralization is the most likely to be preserved in the geological record due to the sulphides being physically shielded from oxidative weathering and mechanical erosion at the seafloor the various styles of vms mineralization can rarely be distinguished using a single criterion in most cases multiple criteria are required mound style mineralization is distinguished by a mound or lens shaped morphology b presence of chimney fragments c presence of abundant sedimented sulphide breccias d location on a stratigraphic boundary ore horizon and e association with a thin horizon or thicker stratigraphic interval of fine grained clastic rocks e g shale mudstone that accumulated at slow sedimentation rates stratiform exhalative mineralization is distinguished by a sheet like morphology prior to deformation b presence of fine grained clastic host rocks that accumulated at relatively slow rates e g mudstone c presence of local or extensive planar stratification replacive mineralization is characterized by a irregular geometry and distribution of sulphide bodies b gradation from massive sulphides to semi massive sulphides and disseminated mineralization with relict textures of the host rock and c originally pumiceous glassy or reactive host rocks emplaced at high depositional rates mass flow deposits lavas carbonate altered mass flow deposits or limestone one deposit or district may comprise two or more of these main styles of mineralization in many cases the main styles of vms mineralization present in a particular region can be predicted from examination of the facies architecture and depositional environments of the host succession recognition of the style s of mineralization that occur in a particular basin or mineral belt enables exploration models to be improved and should influence the strategy of exploration for vms deposits

dating middle palaeolithic red beds in southern greece late quaternary red beds with associated mousterian tools are widely distributed in greece but have not been previously dated by direct methods here we extend the findings of a geological and archaeological study of the interaction between human settlement and landscape in the southern argolid fig 1 during the late quaternary1 3 uranium series dates were obtained from groundwater carbonate crusts formed on mousterian tools found in the southern argolid and from pedogenic carbonates found in the red beds that contain them these dates indicate an age of 50 000 yr bp for the mousterian tools and identify three episodes of red bed formation beginning in the mid pleistocene and ending before the last glacial maximum the radiometric dates are the first for the mousterian in southern greece and the first for alluvial red beds in the mediterranean region

textures of the hellyer volcanic hosted massive sulfide deposit tasmania the aging of a sulfide sediment on the sea floor the relatively undeformed polymetallic massive sulfide ore of the hellyer deposit retains many textures developed during the early crystallization history common textures in the least modified ore away from the main feeder zone include pyrite framboids concentric and radial textured spheres dendritic and fibrous forms breccias mineral banding veins and reniform and crustification textures many are typical of early crystallization within a medium at high degrees of supersaturation some result from open space filling and others indicate disturbances of the sulfide mass possibly due to tectonic activity and volume adjustment the banding could be due to current winnowing most of these textures are found in modern midocean ridge and kuroko massive sulfide deposits but at hellyer the framboids are much more common hexagonal outlines in ore sphalerite indicate derivation of much of the sphalerite by inversion of wurtzite the high content of chalcopyrite in the wurtzite derived sphalerite appears in most cases to have developed by exsolution rather than replacement or coprecipitation although there is local evidence of both processes having operated possibly resulting from early asymmetrical crystal growth comparison of hellyer ore and typical kuroko ores reveals other differences than framboid abundance e g metal contents and ratios mineralogy and sulfur isotope compositions the most significant of which are the relatively high salinities of the hellyer ore fluids these together with evidence of a coeval basin imply sulfide deposition in a brine pool as previously proposed the development of a quenched sulfide mud at the bottom of a basin filled with spent ore fluid with little or no involvement of seawater explains the different mineral content e g lack of fe oxides scarcity of barite in the massive sulfide and the pyrite arsenopyrite assemblage the high metal content lack of chimney structures and differences in sulfur isotope compositions the sulfide mud dominated by fe s phases would be an ideal growth medium for framboidal pyrite the weight of experimental evidence concerning the development of framboidal pyrite points to involvement of metastable precursor fe s phases such as mackinawite and greigite in a weakly oxidized environment oxygen may have been added to the reduced acid brine pool as a result of inward diffusion of oxygen from overlying seawater which is shown to have been oxic by the presence of sessile benthic dendroids in the shales overlying the ore deposit however the level of oxidation was insufficient to form marcasite

geological structure and seabed morphology of the stoupa submarine groundwater discharge system messinia greece detailed marine geological geophysical survey of the submarine groundwater discharge sgd system at stoupa messinia greece was conducted as part of an offshore study aiming at the evaluation of the discharge rate the quality of the water and the investigation of potential ways for exploitation systematic mapping of the seafloor included swath bathymetry seismic profiling and side scan sonar imaging in order to reveal the precise morphology of the submarine discharge site to better understand the structure of the sgd system and the nature and thickness of the sedimentary cover and finally to provide the necessary data for a potential exploitation design the sgd system is located in an e w trending ellipsoidal depression characterized by two depth maxima at 27 and 29 m this depression has been developed on the hanging wall of a n s trending fault whilst the groundwater discharges occur at the base of a 10 m high steep and faulted rocky slope developed on conglomerates or limestone formations also occurring in the coast recent sand deposits cover the seabed around the depression the complex morphology of the discharge site the steep slopes and the rapid changes due to erosion with subsequent slope collapse during enhanced water flow periods do not favor submarine constructions for the exploitation of the sgd system

the middle pleistocene archaeological record of greece and the role of the aegean in hominin dispersals new data and interpretations abstract in the debate about hominin dispersals greece is expected to have been among the core areas for the peopling of eurasia serving as a refugium and source region for re colonizations yet its early pleistocene record is still scarce forming a conspicuous gap in the early human geography of the mediterranean here we investigate this gap and provide for the first time a synthesis of the lower palaeolithic record of greece our study adopts a geoarchaeological approach to explain the current status of the record and argues that the absence of evidence should be understood as the result of the biasing effects of erosional geomorphic processes and not as an indication of a former absence of hominins in this line the potential for archaeological preservation and recovery is assessed as a function of landscape dynamics climatic seasonality tectonic activity high relief and marine inundations have altogether contributed to significant reworking and or total loss of archaeological sites in spatial terms only about 2 5 of the lower palaeolithic record of greece may have survived up to the present on the other hand we interpret recent geological data which show that half of the aegean sea would have been subaerially exposed for most of the early pleistocene our results emphasize the potentially central role of the aegean region in hominin dispersals both as a biogeographical landbridge and as a highly productive landscape for occupation this conclusion opens up new prospects for future fieldwork in an area that was hitherto essentially neglected finally in showing how geomorphic processes bias site distribution patterns the results and methodological perspective developed here can be seen as having implications that are wider than the geographical limits of the greek peninsula they are pertinent to the investigation and interpretation of the early pleistocene archaeological records in the highly dynamic landscapes of southern europe if not in even broader scales

geology genesis and exploration implications of the footwall and hanging wall alteration associated with the hellyer volcanic hosted massive sulfide deposit tasmania australia hellyer is a large 16 2 million metric tons high grade 13 9 zn 7 1 pb 0 4 cu 168 g t ag 2 5 g t au sea floor mound style polymetallic volcanic hosted massive sulfide vhms deposit located in the mount read volcanics of western tasmania the deposit is hosted by the que hellyer volcanics a sequence of late middle cambrian mafic to felsic coherent volcanics and polymict volcaniclastics hydrothermal alteration occurs in the regional footwall immediate footwall and hanging wall alteration in the regional footwall is confined to patchy quartz albite and chlorite with minor sericite epidote and hematite underlying hellyer is a zoned alteration pipe with a central siliceous core quartz sericite which passes into zones of chlorite chlorite carbonate sericite chlorite and finally sericite quartz stringer envelope zone on the margin overlying the central part of the deposit within the hanging wall basalt is a distinctive and zoned alteration plume five alteration zones have been identified fuchsite chlorite carbonate quartzalbite and sericite fuchsite dominated alteration occupies the central portion of the hanging wall alteration plume chlorite and carbonate alteration surrounds the fuchsite zone with carbonate zones forming near to the ore deposit and chlorite zones extending above and lateral to the carbonate outward is quartz ablite alteration which extends laterally into distal sericite alteration mass change calculations for the footwall and hanging wall indicate that in general the footwall alteration zones are depleted in cao na2o la sr ni cr and v but have enrichments of fe2o3 mno mgo k2o s and most metals compared to the host basalt the hanging wall alteration has gained cao k2o na2o co2 s in rb ba ag as mo sb cs and tl while fe2o3 mno mgo p2o5 la sr pb zn th u cd and nd are depleted cao na2o cr v and ni are depleted in the footwall andesite but enriched in the hanging wall alteration plume this relationship suggests that these elements were sourced from the breakdown of feldspars pyroxenes and andesitic groundmass of the footwall lithologies and transported in the hydrothermal fluid into the overlying basalt and precipitated as albite calcite and white micas in the hanging wall alteration the development of alteration associated with the hellyer vhms deposit occurred in three stages stage 1 regional footwall alteration was formed by unfocused hydrothermal convection of seawater down into the recently deposited volcanic pile at temperatures between approximately 250 degrees celsius and 200 degrees celsius and at low to moderate water rock ratios stage 2 alteration formed by structurally controlled fluid flow from a deep intensifying hydrothermal convection system and created the footwall alteration pipe decreasing water rock ratios and temperatures over a range of 350 degrees celsius to less than 200 degrees celsius led to the development of the concentric alteration pipe mineral zones based on modeling of whole rock d18ofr values geochemical modeling and mineral assemblages the siliceous core is interpreted to have formed at temperatures near 350 degrees celsius the chlorite rich alteration zone at 300 degrees celsius to 250 degrees celsius and the outer sericite rich alteration at temperatures of 250 degrees celsius to 150 degrees celsius the final synmineralization fluid flow event stage 3 created the hanging wall alteration plume after rapid burial of the deposit by basalt continuation of upward hydrothermal fluid flow created the zoned hanging wall alteration distribution of hanging wall alteration assemblages suggests a temperature gradient from approximately 250 degrees celsius for the fuchsite zone to lower temperatures 150 degrees celsius for the distal quartz albite and sericite alteration zones alteration mineralogy mineral chemistry lithogeochemistry and stable isotope characteristics of the footwall and hanging wall alteration have been combined into a comprehensive set of vectors which can be used in exploration for vhms deposits in similar geologic settings

seaward dispersals to the ne mediterranean islands in the pleistocene the lithic evidence in retrospect abstract paleolithic artifacts collected in the course of archaeological and geological surveys at particular islands of the ne mediterranean have given birth to arguments for seaward pleistocene dispersals the consecutive implications for the seafaring abilities of archaic hominins have inevitably provoked an ongoing debate the total lack of paleoanthropological evidence and in most cases the absence of a secure stratigraphic context leaves us with the only other pertinent tool of analysis the stone tools preliminary reports presenting lithic collections from the islands have been published since at least the middle of the previous century yet a coherent and critical review of the evidence has hitherto not been attempted in the light of new paleogeographic reconstructions of the aegean region the already published collections are in this paper reviewed and evaluated in terms of their classifications and proposed cultural and chronological attributions and discussed in relation to the arguments for or against pleistocene sea crossings despite the scarcity of the evidence and the many problems associated with their documentation context or interpretations the lithic collections do provide specific information regarding the earliest sea crossings in the region based on the available evidence the majority of the artifacts collected from sites on islands that were most likely insular during parts of the pleistocene have middle paleolithic technological and typological affinities therefore an association with the neanderthals is implied and the possible marine routes are proposed yet further research is needed in order to better appreciate the greek lower paleolithic record thus reevaluate the arguments for lower paleolithic sea crossings in the aegean

crustal block movements from holocene shorelines rhodes island greece abstract signs of up to eight stepped holocene shorelines which have been reported in a previous study on the east coast of rhodes island have been reinvestigated in detail on the basis of a new geomorphological survey identification and petrological analysis of many new samples of exposed marine organic crusts and over 30 radiocarbon datings confirmation was obtained of the view that the island can be charactered by considering small crustal blocks up to a dozen kilometres long with each block being affected by a specific tectonic history and a general trend towards an uplift increasing from south to north two successive phases of submergence emergence have been revealed by petrogenetic sequences in many samples which give evidence of the occurrence of positive and negative vertical movements this implies possible rejuvenation effects of the later submergence phase on the apparent age of pre existing algal crusts and those have been taken into account and estimated the most likely sequence of vertical crustal movements to have occurred has been specified for each block and a time range has been ascribed to each former shoreline independent up and down movements increasing in amplitude from south to north appear in most blocks there is a recurrent periodicity varying from a few hundred to one or at most two thousand years the largest vertical displacement observed during the late holocene a sudden uplift movement of about 3 8 m in the northernmost part of the island is likely to be linked with the earthquake which destroyed the colossus in 222 b c

submerged notches on the coast of skyros island greece as evidence for holocene subsidence article i nfo detailed mapping along the coasts of skyros island aegean sea provided new evidence concerning the rates and the modality of subsidence in the area the results are provided through the study of the shape and the dimensions of the two submerged notches detected around the carbonate coasts of the island itisapparentthattheislandhasbeensubmergednotonlyduetotheglobalsea levelriseduringthelasttwocen turies 1 8 0 3 mm year between 1950 and 2000 but also because of tectonic events testified by the type of the submerged notches some of these tectonic events seem to be of gradual and some of co seismic origin the transition of msl from the retreat point of the lower notch to the retreat point of the upper notch seems to have been produced by co seismic subsidence of about 55 cm at slightly less than 850 years bp

early seafaring activity in the southern ionian islands mediterranean sea abstract this paper summarises the current development in the southern ionian islands kefallinia and zakynthos prehistory and places it within the context of seafaring archaeological data from the southern ionian islands show human habitation since middle palaeolithic going back to 110 ka bp yet bathymetry sea level changes and the late quaternary geology show that kefallinia and zakynthos were insular at that time hence human presence in these islands indicates inter island mainland seafaring seafaring most likely started some time between 110 and 35 ka bp and the seafarers were the neanderthals seafaring was encouraged by the coastal configuration which offered the right conditions for developing seafaring skills according to the voyaging nurseries and autocatalysis concepts

after the cold epigravettian hunter gatherers in blazi cave albania abstract this paper presents the latest results of archaeological research in epigravettian deposits of blazi cave in north central albania this epigravettian site is the first of its kind in albania with a large sample of stone artifacts faunal remains and dating material the study material stems from the last remaining late pleistocene deposits in this cave and therefore characterizes the site in its totality ams 14 c dates place the cultural layers between 18 and 17 ka cal bp this age model coupled with the density of anthropogenic remains attests an intensive use of the shelter by hunter gatherers in the final phase of the last glacial maximum the radiocarbon results place the blazi data into the early phase of the late adriatic epigravettian complex this chronology is corroborated by certain technological and typological traits identified within the stone tool sample analysis of the faunal remains suggests a repeated use of the shelter in the warmer summer period blazi cave functioned as a specialized ibex hunting site and therefore fits into a larger complex of task localities in the wider region

active tectonics of the north and central aegean sea summary in this paper we examine the connection between the westward motion of turkey relative to europe and the extension in and around the aegean sea the principal new data available since the last attempt to synthesize the tectonics of this region by mckenzie 1978 are much improved focal mechanisms of earthquakes constrained by p and sh body wave modelling as well as by first motions these mechanisms show that the faulting in the western part of the aegean region is mostly extensional in nature on normal faults with a nw to wnw strike and with slip vectors directed nnw to nne there is evidence from palaeomagnetism that this western region rotates clockwise relative to stable europe in the central and eastern aegean and in nw turkey distributed right lateral strike slip is more prevalent on faults trending ne to ene and with slip vectors directed ne palaeomagnetic data in this eastern region is more ambiguous but consistent with very small or no rotations in the northern part and possibly anticlockwise rotations relative to europe in the south the strike slip faulting that enters the central aegean from the east appears to end abruptly in the sw against the nw trending normal faults of greece the kinematics of the deformation is controlled by three factors the westward motion of turkey relative to europe the continental collision between nw greece albania and the apulia adriatic platform in the west and the presence of the hellenic subduction zone to the south as the right lateral slip on the north anatolian fault enters the aegean region it splays out becoming distributed on several parallel faults the continental shortening in nw greece and albania does not allow the rotation of the western margin of the region to be rapid enough to accommodate this distributed e w right lateral shear and thus leads to e w shortening in the northern aegean which is compensated by n s extension as the southern aegean margin can move easily over the hellenic subduction zone the dynamics of the system once initiated is self sustaining being driven by the high topography in eastern turkey and by the roll back of the subducted slab beneath the southern aegean the geometry of the deformation resembles the behaviour of a system of broken slats attached to margins that rotate in spite of its extreme simplicity a simple model of such broken slats is able to reproduce quantitatively most of the features of the instantaneous velocity field in the aegean region including the slip vectors and nature of the faulting in the eastern and western parts the senses and approximate rates of rotation the overall extensional velocity across the aegean and the distribution of strain rates as seen in the seismicity and topography or bathymetry and using geodetic measurements as part of this study we re examined the relation between the surface faulting and the focal parameters determined seismologically for the three large 1981 gulf of corinth earthquakes and reassessed the evidence for associating particular earthquakes in the sequence with observed surface faulting an important result is that in one of the events there is a resolvable discrepancy between the slip vector measured at the surface and that determined from the seismic body waves

geochemical modeling of the zoned footwall alteration pipe hellyer volcanic hosted massive sulfide deposit western tasmania australia the mineralogy of hydrothermal alteration assemblages siliceous core chlorite zone sericite zone in the footwall pipe of the hellyer volcanic hosted massive sulfide vhms deposit is controlled mainly by the temperature ph and redox state of the hydrothermal fluids based on the results of our numerical modeling the zoned alteration system could have formed by a combination of water rock interaction and cooling with a siliceous core predicted to form at the center of the conduit passing outward to a chlorite dominated zone a sericite rich zone and finally grading out to unaltered andesite these mineralogical changes relate to a gradual evolution of fluid chemistry water rock ratio ph and temperature from the core to the margin of the system initial temperatures were probably close to 350 degrees c and the hydrothermal fluids were reduced h2s dominated at low temperatures 200 degrees c a peripheral alteration zone consisting mostly of k feldspar chlorite sericite and hematite is predicted to form this low temperature zone has not been recognized at hellyer but elevated k2o contents and local k feldspar development have been noted at other vhms deposits suggesting that this zone might form at low temperatures and low water rock ratios in the footwall of vhms deposits if the existence of barren outer k feldspar alteration zones is confirmed the findings could have important implications for exploration specifically with regards to distinguishing ore related alteration zones from barren alteration systems

high resolution seismic reflection profiles for the reconstruction of postglacial transgressive shorelines an example from greece abstract in 1982 we carried out a shallow penetration high resolution seismic profiling study on the shelf of the southern argolid peloponnesos greece to identify and map the shores of the late pleistocene and holocene and to establish their coastal environments portable equipment and a local boat were used the lowest glacial shore occurs at 115 to 118 m within the range of global values the subsequent rise across the distinct old land surface left behind many shore features scaps beaches and beach ridges channels and lagoons now buried under a few meters of post transgressive deposits these features cluster at a small number of depths below present sea level suggesting that the rise of the sea usually too fast to leave an imprint was episodically interrupted by brief stillstands or even temporary reversals of climatic or tectonic origin the clusters can be roughly dated with reference to a global sea level rise curve after 6000 yr b p sparse archaeological data establish a local curve the seismic profiling technique convenient and not costly holds promise for the identification of postglacial shores elsewhere prior to sampling for dating it has wide application for environmental reconstructions of vanished coastal zones as a basis for prehistoric resource assessments these applications are illustrated with examples from this study

carbon and oxygen isotope halo in carbonates related to the mcarthur river hyc zn pb ag deposit north australia implications for sedimentation ore genesis and mineral exploration a study of carbon and oxygen isotope ratios in fine grained sedimentary dolomite in the barney creek formation of the mcarthur basin demonstrates the presence of an extensive isotope halo surrounding the giant stratiform hyc zn pb ag deposit dolomite within the halo shows an 18o enriched and 13c depleted isotope signature 18o 23 to 26 smow 13c 2 to 3 5 pdb relative to normal proterozoic sedimentary dolomite beyond the halo 18o 20 23 and 13c 0 to 2 the c o isotope halo within the dolomitic siltstones extends at least 15 km southwest of the hyc deposit and approximately coincides with a previously defined lithogeochemical halo of elevated fe mn zn pb and tl dolomitic siltstone lamellae within the stratiform zn pb ag ores at hyc exhibit an isotopic range similar to that of the halo dolomites suggesting that the ore and halo equilibrated with the same hydrothermal fluid modeling of isotopic exchange accompanying fluid rock interaction suggests that the halo dolomites equilibrated with low temperature fluids 50 120 c which were enriched in 18o 18o 5 5 but with an average crustal carbon isotope signature 13c 6 1 our preferred interpretation is that the oxygen and carbon isotope halo at hyc is related to the development of an extensive brine pool this pool was deepest in the vicinity of the hyc deposit adjacent to the emu fault and it became shallower to the southwest away from the fault using the carbon isotope fractionation equation between dolomite and hc batchmode documentclass fleqn 10pt legalpaper article usepackage amssymb usepackage amsfonts usepackage amsmath pagestyle empty begin document o 3 mbox end document it is possible to estimate the temperature variation at the base of the brine pool during the accumulation of the barney creek formation brine pool temperatures were highest in and adjacent to the hyc deposit 40 70 c and decreased to values of 17 to 30 c remote from the deposit these temperatures are similar to those recorded in the red sea brine pool associated with the atlantis ii metalliferous sediment deposit based on our work at hyc and lady loretta strata bound 18o enriched carbonate lithogeochemical halos may be a characteristic of the proterozoic stratiform zn pb ag deposits of northern australia these halos are more extensive than the narrow 18o depletion halos recorded in dolomites surrounding skarn mississippi valley type and irish style zn pb deposits this fundamental difference in the isotopic halo characteristics of these groups of zinc deposits is probably related to the low temperature synsedimentary brine pool origin of the north australian sedex deposits in contrast to the various replacement and open space fill origins of skarn mississippi valley type and irish style deposits

partially melted lithic megablocks in the yardea dacite gawler range volcanics australia implications for eruption and emplacement mechanisms lithic megablocks ranging from 200 m felsic volcanic unit in the mesoproterozoic gawler range volcanic province grv of south australia throughout its vast extent the yardea dacite shows typical lava like features in that it is massive columnar jointed and evenly porphyritic with 30 40 crystals in a spherulitic and granophyric groundmass in addition flow banding is present at many locations the megablocks are abundant at two sites 50 km apart but isolated megablocks and smaller 6 cm lithic clasts are also scattered throughout the unit at both sites the megablocks are matrix supported non graded randomly oriented and show no evidence of being confined to a particular stratigraphic level in the dacite the most abundant and largest megablocks are granitoids derived from older basement and from early crystallised plutons of the hiltaba suite which is broadly coeval and comagmatic with the grv the granitoid megablocks have been partially melted most likely prior to eruption when resident in the thermal aureole of the yardea dacite magma chamber the lithic megablock occurrences are unlike coarse pyroclastic breccias but are similar in distribution and abundance to xenoliths in lavas consistent with the lava like character of the host dacite using reasonable estimates of megablock density magma density and magma viscosity we show that the rise rate of the dacitic magma exceeded the settling velocity of the megablocks implying that they could have been entrained and erupted effusively all but the largest and least melted megablocks would have remained suspended or else settled very slowly in the dacitic lava during outflow the rapid rate of magma withdrawal required to produce such an extensive felsic sheet could have also triggered disintegration of the thermally stressed wallrock surrounding the magma chamber dislodging megablocks that were later entrained and effusively erupted

contemporary kinematics of the southern aegean and the mediterranean ridge summary this study focuses on the kinematics of the southern aegean and the mediterranean ridge mr a quantification of the deformation of the mr is essential for both evaluating physical models of accretionary wedges in general and for obtaining a self consistent model of the surface deformation over the entire nubia eurasia nu eu plate boundary zone in the eastern mediterranean previous kinematic studies have not properly considered the deformation field south of the hellenic arc although this study focuses on the deformation field of the mr we also discuss the kinematics of the southern aegean because the geometry and movement of the hellenic arc determine to a large extent the kinematic boundary conditions for kinematic studies of the mr we calculate a continuous velocity and strain rate field by interpolating model velocities that are fitted in a least squares sense to published global positioning system gps velocities in the interpolation we use information from a detailed data set of onshore and offshore active faulting to place constraints on the expected style and direction of the model strain rate field in addition we use the orientations of tracks left by seamounts travelling into the wedge to further constrain the offshore deformation pattern our model results highlight the presence of active shear partitioning within the mediterranean ridge high compressional strain rates between the ridge crest and the deformation front accommodate approximately 60 70 per cent of the total motion over the wedge and the outward growth rate of the frontal thrust is 4m m yr 1 strain partitioning within the wedge leads to 19 23 mm yr 1 of dextral motion at the wedge backstop contact of the western mr whereas the pliny and strabo trenches in the eastern mr accommodate 21 23 mm yr 1 of sinistral motion the backstop of the western mr is kinematically part of the southern aegean which moves as a single block the aegean block ae at 33 34 mm yr 1 in the direction of s24 w 1 towards stable nubia nu our model confirms that there is a clear divergence between the western and eastern hellenic arc and we argue for a causal relation between the outward motion of the arc and the gradient in the regional geoid anomaly our results suggest that a significant driving source of the surface velocity field lies south of the hellenic arc and only for the southeastern aegean could there be some effect as a result of gravitational collapse associated with density differences within the overriding plate

the hellenic margin from eastern crete to rhodes preliminary results abstract complementary data on previously surveyed areas have been obtained and more than 3000 km of continuous seismic profiles along the eastern hellenic continental margin between eastern crete and rhodes have been made among the important preliminary observations we note the relatively great thickness due to probable coarse rapid fill of the margin sedimentary cover which is also intensively affected by extensional faulting the presence of a well defined sedimentary basin lying between the strabo and pliny trench where evaporitic strata exist but where the acoustic facies also suggest coarse fill is probably derived from surrounding topographical highs exposed to erosion during the messinian finally we observe a progressive and perplexing change of the strabo trench structural pattern from west to east which indicates a more complex tectonic regime than we expected we speculate that at the southern margin of the rhodes basin northward thrusting may now be occurring

disruption of the hellenic arc late miocene extensional detachment faults and steep pliocene quaternary normal faults or what happened at corinth 1 extensional faults exposed in the peloponnesus and mainland greece most of which are described here for the first time record a transition from regional extension of the aegean domain to the modern tectonic system the east peloponnesus detachment system trends north northwest from the southern peloponnesus to 30 km north of the gulf of corinth dips gently northeast and is late miocene early pliocene in age it has a minimum displacement of 25 30 km and appears to be the youngest of the regional scale extensional systems with significant displacement that formed parallel to the hellenic arc the partially coeval east sterea extensional system which extends from the gulf of corinth to the aegean sea contains low angle normal faults that both crosscut and trend parallel to older structures of the hellenic arc late miocene to early pliocene displacement within this zone disrupted the arc parallel structures of the hellenides upper pliocene quaternary normal faults which trend approximately east west and generally dip steeply at the surface continue the disruption of the hellenic arc much of the subsidence within the gulf of corinth appears to be unrelated to the younger faults and is instead related to the motion on the east peloponnesus detachment which crosscuts the modern graben

internal structure and evolution of the late quaternary sequence in a shallow embayment the amvrakikos gulf nw greece abstract the late quaternary stratigraphic pattern of the amvrakikos gulf in the eastern mediterranean has been studied on the basis of the analysis of high resolution seismic profiles and short sediment cores lowstand transgressive and highstand systems tracts have been identified that are configured in a major depositional sequence of a fifth order sea level cycle during the last glaciation when the sea level was lowered by 55 m relative to its present position ca 50 ka bp the amvrakikos gulf was probably emerged giving rise to a subaerial erosion and fluvial incision in the western shallow part of the gulf and b development of a paleo lake in the eastern deepest domain until the early phase of the post glacial transgression ca 11 50 ka bp a paleo river characterized by a dense network of v shaped valleys was draining the western part of the gulf and flowing into the ionian sea in the isolated eastern part lowstand lacustrine deposits deltaic and prodeltaic units accumulated within the paleo lake at the latter stage of the last post glacial transgression ca 11 ka bp seawater entered the gulf and the transgressive systems tract was deposited consisting of incised channel fills beach shoreface deposits and delta prodelta wedges buried terraces have been identified also within this transgressive tract that reveal a step like sea level rise since ca 6 ka bp when the sea level reached its present day position a distal prodeltaic unit has been deposited and overlain by prograding deltaic wedges the spatial distribution of these wedges provides evidence of a continuous shifting of the river mouths during holocene the recent sedimentation patterns are related to the terrigenous inputs primarily from the arachthos river located in the northeastern part of the gulf and secondarily from the louros river located in the northwestern part

coastal uplift earthquakes and active faulting of rhodes island aegean arc modeling based on geodetic inversion the geodetic inversion technique was used to model the fault pattern responsible for the uplifted holocene notches along the ne rhodes island coast se edge of the hellenic aegean arc input in the modeling was the elevation of uplifted notches up to 6000 yr old which are interpreted to reflect remains of fossil shorelines to testify to a series of earthquakes producing both uplift and subsidence i e to elastic dislocations and to correspond to geodetic data senso lato these shorelines up to 3 8 m high were probably originally continuous along the whole of the 75 km long se rhodes coast possibly locally disturbed by minor normal faults and reflect the last phases of the uplift and tilting of the island as a rather rigid block since late pliocene their radiocarbon dating was further refined from archeological data testifying to an about 1 m subsidence associated with the 227 bc earthquake followed by 3 m seismic uplift inversion constrained by the hypothesis of a compressional fault offshore rhodes was based on standard uniform slip elastic dislocation analysis it proved to depend only weakly even on extreme glacio isostatic corrections and indicated that coastal uplift is dominated by a main compressional fault zone offshore sub parallel to the island coast with normal faults inland reflecting thin skin tectonics this fault pattern similar to that of western crete is confirmed by seismic reflection profiles indicating a major reverse close to the modeled fault and can explain 1 the occurrence of strong m 7 5 historical earthquakes producing tsunamis and destruction on an east mediterranean scale 2 the alternation of uplift and subsidence as a result of fault shift inside the same fault zone and 3 the long term uplift of the island as a rather conjugate effect of the formation of an about 4 5 km deep 5 myr old marine basin se of rhodes bounded to the nw by the modeled fault zone the seismic risk of rhodes higher in its ne part of the island and than what was previously believed is associated with strong m 7 5 earthquakes producing widespread destruction tsunamis coastal uplift and coastal subsidence

geology and archaeology submerged landscapes of the continental shelf an introduction sea level change has influenced human populations globally since prehistoric times even in early phases of cultural development human populations were faced with marine regression and transgression associated with the glacial interglacial climatic cycle amplified by glacio isostatic adjustments in some regions global marine regression during the last glaciation changed the palaeogeography of the continental shelf converting former marine environments to attractive terrestrial habitats for prehistoric human occupation and adding an extensive new increment of land in the case of europe amounting to an additional 40 of the existing land area and on a global scale to some 20 million km of additional territory that is now submerged these areas of the shelf were used as hunting and gathering areas and as pathways of dispersal between regions and between continents until they were resubmerged by the post glacial marine transgression they also most probably witnessed the earliest developments in seafaring marine exploitation and permanent settlements based on modern marine research technologies and the integration of large databases proxy data are now becoming available for the reconstruction of these submerged quaternary landscapes concerted efforts are also now being devoted to the search for prehistoric archaeological sites and artefacts on the seabed often in collaboration with marine scientists this search has been stimulated by the increasing amount of material that has demonstrably survived inundation often with excellent preservation of organic remains by closer collaboration with offshore industry and by the growing realization of the importance of these submerged data for understanding human prehistoric developments during periods of rapidly changing climate and environment moreover these new research trends are not simply being driven by an archaeological need for scientific and technological input from other disciplines but by collaborations involving genuine mutual benefit in which all partners have something to gain archaeological problems often pose new questions about geological change stimulating new techniques of observation new technologies and new investigations which in their turn can offer new data often at higher resolution and with better dates in relation to geological and environmental issues such as sea level change and palaeoclimatic variability on the continental shelf the expansion of early human populations to occupy new territory and new continents is one of the great narratives of human evolution it is currently a theme of wide interest and topicality and has received significant impetus and publicity from the new science of palaeogenetics together with ongoing discoveries of new fossil and archaeological material and new studies of palaeoclimate and palaeoenvironment the field itself is rapidly expanding leading to new discoveries and new controversies grine et al 2009 gamble 2013 smith ahern 2013 all the current indications are that the human species originated in africa with at least two major episodes of dispersal the earliest some time after about 2 myr ago led to the expansion of homo ergaster erectus populations across southern europe and asia extending from britain in the west to china and indonesia in the east and south the second involved our own species homo sapiens anatomically modern humans or amh and took place some time after about 200 ka this resulted in the replacement of earlier hominin populations in europe and asia and expansion further afield into new guinea and australia certainly involving sea crossings over distances of at least 50 km by about 50 ka to the higher latitudes of northern eurasia with entry into the americas by at least 15 ka and into new territory exposed by the melting of the northern hemisphere ice sheets less than 10 kyr ago anthropological and archaeological investigations of these processes are directly connected

late quaternary sedimentation on the north aegean continental margin greece the late quaternary seismic stratigraphy of the north aegean continental shelf and adjacent basins has been interpreted from boomer and 3 5 khz seismic profiles ages derived from shallow cores and offshore wells and relative offsets on small synsedimentary faults provide chronological control sea level history inferred from seismic stratigraphy correlates with the global eustatic sea level record based on oxygen isotopic curves outer shelf progradation correlates with lowstands of sea level in isotopic stages 2 3 and 6 whereas shelf wide transgression surfaces correspond to the stage 6 5 and 2 1 transitions when rapid deglaciation occurred the present depth of the delta plain formed on the outer shelf during the late stage 6 lowstand provides a dated and originally horizontal marker for estimating rates of tectonic subsidence gross distribution of sediment facies is similar in both tectonically stable and active areas the shelf break formed by delta progradation but is marked by faults in most places because of the accommodation provided by graben subsidence rates of 0 3 1 5 mm yr standard sequence stratigraphic analysis can be applied to these sediments deposited during high amplitude quaternary sea level oscillations high rates of subsidence result in the preservation of an unusually complete record of sea level change major lowstand progradation is dependent on the duration rather than the magnitude of sea level lowstand the long glaciations in isotopic stages 6 12 16 and 22 resulted in the most prominent seaward progradation on the margin sandy lowstand turbidite deposits formed only when there was rapid fall in sea level otherwise sand was trapped on delta tops and silty muds were deposited in deep water

hydrothermal fluid migration and brine pool formation in the red sea the atlantis ii deep numerical heat and fluid flow simulations of the atlantis ii deep in the red sea were conducted to investigate the development migration and discharge of hydrothermal fluids into a submarine depression and determine the conditions necessary to form a brine pool high salinity fluids are predicted to form by leaching miocene evaporates migrate and convect within young oceanic crust and discharge onto the seafloor predicted fluid discharge temperatures t max 301 c discharge fluid velocities v max 0 09 m s and salinities s max 21 wt increase over time and reach values comparable to modern seafloor observations established convection patterns and discharge behavior are robust and are not greatly affected by geometry of rock property changes modeling results were used to calculate the minimum conditions for hydrothermal fluids from a developing hydrothermal system to mix with seawater reverse buoyancy and begin to form a brine pool in a submarine depression under conditions encountered on the seafloor t 25 300 c s 5 25 wt fluid mixtures predicted to pond on the seafloor range from late in the mixing process 99 at low temperatures t 26 c to much earlier 36 mixing at higher temperatures t 94 c a model of brine pool evolution is proposed that describes the processes and conditions necessary to initiate brine pool formation and compares formation conditions with accumulated ore material in the atlantis ii deep and other locations

a comparison of geodetic and finite strain pattern in the aegean geodynamic implications abstract a comparison of the active strain pattern of the aegean constrained by global positioning system measurements and the oligo miocene finite strain field shows some striking similarities in terms of direction and rates of extension the geometry of extension at crustal scale is also very similar with north dipping normal faults connecting near the brittle ductile transition to shallow north dipping shear zones this pattern of extension is not significantly modified by the recent extrusion of the motion of anatolia and aegea the persistence over more than 25 myr of the same pattern of extension suggests that the cause for extension resides within the aegean lithosphere gravitational collapse allowed by extensional boundary conditions after 30 ma slab retreat is the primary cause for post orogenic extension in the aegean and western anatolia

quaternary transgressive regressive cycles in the gulf of argos greece abstract borings in the argive plain reveal cycles of marine incursions each ending with a mediterranean soil profile and followed by a prograded fluvial and coastal wedge the sediment prism of the gulf of argos shelf visible in high resolution seismic reflection profiles also consists of transgressive and regressive depositional sequences identified by onlap downlap and truncation of deposits at least four major reflectors recognizable by their high acoustic impedance and erosional features can be correlated across the shelf the sediments between each pair of reflectors represent the seaward part of a set of transgressive and regressive marine deposits they can be matched to the stratigraphic sequence on land where each marine unit is topped by a soil corrected for subsidence the terminations of the onlapping and downlapping units define a local sea level history its time scale can be derived from a comparison with the eustatic sea level history deduced from ocean cores thus marine seismic reflection data can be used for the correlation of quaternary oceanic and terrestrial chronologies

geology fluid inclusions and oxygen isotope geochemistry of the baiyinchang pipe style volcanic hosted massive sulfide cu deposit in gansu province northwestern china the baiyinchang massive sulfide cu deposit zheyaoshan and huoyanshan mines is hosted by an early cambrian submarine felsic volcanic succession within an extrusive cryptodome associated with an overlying basaltic flow in a late proterozoic early paleozoic submarine volcanic belt in the north qilian orogen northwestern china the deposit is comprised of two mineralized zones a 30 cm thick strata bound zn rich sulfide lens associated with hematitic fe mn cherts and an underlying discordant massive ore dominated sulfide zone enveloped by a hydrothermal alteration pipe that is zoned from chlorite in the center to quartz sericite at the margin the discordant sulfide zone accounts for 90 percent of the cu reserves of the zheyaoshan mine it consists of four main ore types 1 pipelike pyrrhotite pyrite chalcopyrite ore 2 massive sulfide ore 3 a disseminated ore halo and 4 footwall stringer ore the pyrrhotite pyrite chalcopyrite pipe has an elliptical shape in plan and is 30 50 m across the pipe partially replaces the overlying massive pyrite lens and extends downward at least 150 m to be gradually replaced by chalcopyrite rich stringer veins and chalcopyritebearing quartz veins surrounded by a discordant hydrothermal alteration envelope massive chalcopyrite pyrite lenses discordant to volcanic bedding containing relict patches of felsic volcanic host rocks are commonly enveloped by a disseminated sulfide halo within a chloritized volcanic unit these features suggest that zheyaoshan is a pipe style deposit that formed mainly by subsea floor replacement of volcanic host rocks studies of fluid inclusions indicate that there are four types 1 type i two phase aqueous fluid inclusions 2 type ii daughter mineral bearing multiphase fluid inclusions 3 type iii co2 rich fluid inclusions and 4 type iv ch4 rich fluid inclusions type ii inclusions have high homogenization temperatures th ranging from 320 to 430 c contain high salinity fluids 31 38 wt nacl equiv and coexist with co2 rich fluids found in vapor rich high th up to 487 c moderate salinity 10 16 wt nacl equiv inclusions in the discordant sulfide zone and associated altered rocks suggesting a possible contribution of a magmatic fluid to the hydrothermal system the coexistence of vapor rich high th 300 c and aqueous low th 220 c type i fluid inclusions in the stringer zone suggests that heated seawater mixed with magmatic fluid gas in the feeder zone most type i fluid inclusions in the massive chalcopyrite pyrite body and in the strongly chloritized pipe have a low th 62 225 c and high salinities 15 0 23 0 wt nacl equiv suggesting that a dense brine zone developed in fractures in the subsea floor where sulfides accumulated by open space filling and replacement of host volcanic rocks eleven quartz samples from the overlying discordant sulfide zone yielded a restricted range of 18o values between 8 8 and 11 1 per mil from which we calculate that the corresponding hydrothermal fluids had 18o values ranging from 5 3 to 3 1 per mil over a temperature range of 160 to 278 c whole rock 18o values

the spectrum of ore deposit types volcanic environments alteration halos and related exploration vectors in submarine volcanic successions some examples from australia variations in shape metal content alteration mineralogy and volcanic host rocks of the ore deposits in the two major volcanic hosted massive sulfide vhms districts of eastern australia the cambrian mount read volcanics and the cambro ordovician mount windsor subprovince strongly reflect their volcanic environment conditions of ore formation and hydrothermal alteration processes lens and sheet style polymetallic zinc rich deposits such as rosebery hellyer que river and thalanga are considered to have formed in moderate to relatively deep water environments 500 1 000 m these deposits probably formed either on the sea floor e g hellyer que river or by replacement of porous volcaniclastic units directly below the sea floor e g rosebery the footwall alteration associated with these polymetallic vhms deposits was controlled by host rock permeability and porosity which are in turn related to volcanic facies type degree of fracturing and synvolcanic structural architecture focusing of hydrothermal fluids along synvolcanic structures has resulted in well zoned chlorite sericite footwall alteration pipes within footwall lavas at hellyer on the other hand diffuse fluid flow through very thick pumice breccia at rosebery and hercules has resulted in strata bound sericite dominated footwall alteration zones parallel to the paleosea floor and the ore lenses massive and disseminated pyritic cu au deposits such as those in the mount lyell field and at highway reward formed by subsea floor replacement and are associated with only minor zinc lead massive sulfide ore these deposits formed from higher temperature fluids 300 degrees c in which copper transport is enhanced and are commonly located in felsic volcanic centers dominated by shallow porphyritic intrusions e g highway reward the cu au ore lenses may be strata bound e g mount lyell or crosscutting pipes e g highway reward depending on the structure and permeability characteristics of the felsic volcanic host rocks the presence of high sulfidation alteration minerals e g pyrophyllite zunyite in some of the cu au deposits e g mount lyell field indicates that fluids were relatively acidic and suggests the possibility of magmatic fluid input into the hydrothermal system alteration zonation associated with the cu au vhms deposits is more symmetrical than that of the zn rich deposits with sericite rich alteration extending into the hanging wall in keeping with the subsurface replacement origin of these deposits synvolcanic gold rich deposits with high gold base metal ratios are less common than the cu au and zn rich vhms ore types the gold rich ores e g henty south hercules are strata bound in nature have low sulfide contents and are associated with central zones of intense silicification surrounded by envelopes of sericite pyrite and carbonate alteration volcanological and geochemical studies at henty indicate the gold rich ore formed by the replacement of particular volcanic units deposited in a relatively shallow water environment dominated by volcaniclastic facies lavas and limestones this spectrum of cu au zn rich and au only deposits in the mount read volcanics and the mount windsor subprovince is interpreted to represent a continuum from classic sea floor vhms ores toward those with features more akin to porphyry cu au and epithermal au ag deposits this spectrum relates to the interplay between factors in the submarine volcanic environment and the character of the hydrothermal fluid as follows 1 proportions of volcaniclastic lava and subvolcanic intrusive facies 2 depth of seawater 3 permeability and porosity of volcanic host rocks 4 balance between magmatic components and seawater components in the ore fluid and 5 temperature and acidity of the ore fluid mineralogical lithogeochemical and isotopic studies have revealed a range of alteration vectors useful in exploration for both the zn rich and cu au vhms deposits carbonate and white mica compositional variations are highlighted as important mineralogical vectors thallium and antimony halos may be useful trace element vectors and oxygen and sulfur provide important isotope vectors toward the center of the hydrothermal system

the tectonic development of the hellenic arc and the sea of crete a synthesis abstract we use field analyses together with interpretation of aerial photographs orbital imagery and sea beam data to define more accurately the geometry of fault systems in the hellenic arc the tectonics of the area are dominated by extensional processes related to normal faulting we then use sea beam data previous oceanographic studies and extrapolation of field analyses on surrounding islands to describe the fault pattern of the cretan sea basin which is found consistent with the land fault pattern the mechanisms of the late neogene and quaternary deformation of the central and southern aegean region are analysed in terms of stress trajectories as revealed by field studies of fault populations we then examine the subsidence of the sea of crete in terms of a model of uniform stretching of the lithosphere the opening of the sea of crete was cylindrical and did not result in bending of crete this leads us to modify the southern portion of an earlier kinematic reconstruction of aegea in agreement with recent paleomagnetic results the implications of the opening of the sea of crete on the tectonic evolution of the straits to the west and east of crete are discussed finally the uplift of the outer arc is explained by underplating due to subduction

discussion sulphur isotope composition of the brunswick no 12 massive sulphide deposit bathurst mining camp new brunswick implications for ambient environment sulphur source and ore genesis the authors w d goodfellow and j m peter report an impressive amount of chemical data on the brunswick no 12 orebody one of the world s largest volcanic associated massive sulphide deposits they have proposed that most of the sulphur in the massive sulphide ore and the pyrites in adjoining sediments of the patrick brook formation was probably derived from an overlying anoxic seawater column in which sulphate reduction had taken place the resulting h2s having mixed with venting metal rich fluids the principal lines of evidence brought in to support this idea are 1 the sediments of the patrick brook formation underlying the footwall sedimentary and volcanic rocks of the nepisiguit falls formation which hosts the orebody have s c values and mn and fe contents that indicate anoxic conditions in the seawater during sedimentation 2 the 34s values of the sulphides in the ore types and the underlying feeder zone are similar to those of pyrites in the patrick brook formation and to coeval pyrites in the selwyn basin and 3 there is no alternative source of reduced sulphur because there would be inadequate sulphate remaining in deep circulating seawater to provide sufficient reduced sulphur for ore formation and there is little evidence for the presence of evaporite sulphate in the deep footwall sequence the significance of their major lines of evidence and also those of lentz et al 1996 is discussed below

westward propagation of the north anatolian fault into the northern aegean timing and kinematics we present new evidence for the propagation processes of the north anatolian fault folding in the dardanelles straits region allows us to document the timing of the deformation preceding and the finite displacement after the passage of the propagating tip of the fault the accuracy of the observations is due to interplay between deformation and the sea level changes in the mediterranean the well known messinian regression followed by the pliocene transgression the long term kinematics around the sea of marmara pull apart total displacement of about 85 km over the past 5 m y is similar to the present day kinematics deduced from space geodesy at a larger scale westward propagation of the north anatolian fault over nearly 2000 km in the past 10 m y appears to be associated with strain recovery suggesting that the continental lithosphere retains long term elasticity

geographic changes in the aegean sea since the last glacial maximum postulating biogeographic effects of sea level rise on islands abstract in order to assess how the last sea level rise affected the aegean archipelago we quantified the magnitude and rate of geographic change for the aegean islands during the last sea level rise episode 21 kyr bp present with a spatially explicit geophysical model an island specific area distance change adc typology was constructed with higher adc values representing a higher degree of change the highest fragmentation rates of the aegean archipelago occurred in tandem with the largest rates of sea level rise occurring between 17 kyr and 7 kyr ago sea level rise resulted in an area loss for the aegean archipelago of approximately 70 spatiotemporal differences in sea level changes across the aegean sea and irregular bathymetry produced a variety of island surface area loss responses with area losses ranging from 20 to 90 per island in addition sea level rise led to increased island isolation increasing distances of islands to continents to 200 for some islands we discuss how rates of area contractions and distance increases may have affected biotas their evolutionary history and genetics five testable hypotheses are proposed to guide future research we hypothesize that islands with higher adc values will exhibit higher degrees of community hyper saturation more local extinctions larger genetic bottlenecks higher genetic diversity within species pools more endemics and shared species on continental fragments and higher z values of the power law species area relationship the developed typology and the quantified geographic response to sea level rise of continental islands as in the aegean sea present an ideal research framework to test biogeographic and evolutionary hypotheses assessing the role of rates of area and distance change affecting biota

consonorm_lg new normative minerals and alteration indexes for low grade metamorphic rocks the consonorm lg method provides a standardized solution for approximating metamorphic parageneses as well as indexes for estimating chemical and mineralogical changes caused by hydrothermal alteration consonorm lg is designed for rocks dominated by silicates fe ti oxides and or carbonates and it approximates the main parageneses of greenschist and lower amphibolite grade metamorphic rocks for three sets of temperature and pressure conditions 350 c and 2 5 kbars 450 c and 2 5 kbars 575 c and 2 kbars for each model the norm calculates the main paragenesis using an acfmnk tetrahedron a convenient way of representing a large number of silicate assemblages in addition to silicate minerals consonorm lg calculates fe ti oxides and other accessory minerals from minor elements as well as sulfides from analyzed s or from analyzed metals and carbonates from analyzed co2 or from normative co2 estimated from loss on ignition loi consonorm lg also calculates several alteration indexes to estimate fe mg e g chloritization ca e g propylitic alteration na and k acid alterations e g sericitization phyllic alterations and al gain e g argillization carbonatation indexes are also calculated using the amount of normative minerals formed by this type of alteration i e carbonates chlorite and muscovite the normative calculation is validated using published whole rock analyses and petrographic descriptions alteration indexes are validated using several natural samples of alteration halos around base metal and gold deposits

in situ u pb geochronology and sulfur isotopes constrain the metallogenesis of the giant neves corvo deposit iberian pyrite belt abstract the large scale high grade sn ores and the cu sn metal association in the volcanic massive sulfide vms ores in neves corvo are unique among vms deposits not only in the iberian pyrite belt but also worldwide thus the exceptional nature of the neves corvo deposit calls for unusual metallogenic processes previous efforts to constrain these processes have been hampered by a lack of high precision ages for the mineralization this has led to a debate as to whether tin mineralization occurred at the same time as the associated volcanism and vms style mineralization or is the result of later processes events associated with the hercynian orogeny we report in situ u pb dating results of hydrothermal cassiterite and sulfur isotopic compositions of sulfides in the neves corvo deposit that place tight constraints on the timing of mineralization and on the origin of the hydrothermal ore forming fluids the cassiterite samples yield u pb ages of the sn mineralization of 363 366 ma identical to the age of the host volcanic rocks 34s values range from 32 3 to 17 4 among the different vms ore types and are largely consistent with microbiological reduction of seawater sulfate but with some positive values resulting from thermochemical sulfate reduction in contrast the sn rich ores have a limited range in 34s that clusters near 0 which suggests derivation from magmatic fluids hence the unusually high sn grades at the neves corvo deposit are interpreted to be derived from fluids exsolved from a hidden granitic source essentially synchronous with formation of the volcanic rocks and vms mineralization

metallogenesis at the neves corvo vhms deposit portugal a contribution from the study of fluid inclusions abstract neves corvo one of europe s most outstanding currently producing mines was the focus of two recent studies on fluid inclusions the present contribution provides new data and is intended to give an overview of the fluid inclusion research carried out on the deposit the study focuses on samples from all stratigraphic levels above the ores in the copper and tin ores and in the main thrust in massive copper ore pyrite plus chalcopyrite occur along growth zones in quartz suggesting that quartz and sulfides are coeval in these samples the most frequent fluid is a low salinity h 2 o nacl fluid but an aqueous carbonic fluid of low density also occurs especially in intercrystalline domains homogenization temperatures show two distinct modes one at 160 to 170 c and the other between 220 and 280 c in one sample a high salinity h 2 o nacl fluid with 30 wt nacl equiv was observed this fluid is interpreted to represent the product of phase separation at depth and it could have been derived from either seawater or a magmatic fluid however the most likely cause for ore deposition was temperature decrease it seems however that three separate events are registered low medium and high temperature in the evolution of the volcanogenic hydrothermal system in all but the massive ore and the main thrust the dominant fluids are low salinity aqueous carbonic in character frequently showing liquid co 2 at room temperature pressure oscillations frequently found in these fluids are interpreted as due to variations in the pressure regime from lithostatic to hydrostatic at the same depth co 2 ch 4 are thought to have resulted from reactions with organic matter dispersed in the metasediments which are very common at the stockwork and rubane ores and below the orebodies the highest p t conditions during metamorphism were estimated around 320 mpa and 350 c the rubane ores are interpreted as metamorphogenic ores as they were formed during orogeny also the fissural copper ore is better described as a metamorphosed stockwork

quaternary evolution of the corinth rift and its implications for the late cenozoic evolution of the aegean summary we present geological and morphological observations at different scales to constrain rates of faulting and the distribution of deformation in the seismically active aegean region we focus first on the 130 km long corinth rift an asymmetric graben where a flight of terraces of marine origin are uplifted we show that the edges of the terraces lie in the footwall of the normal fault bounding the corinth rift and correspond to sea level highstands of laic pleistocene age using a detailed analysis of aerial and spot imagery supported by field observations we have mapped 10 terrace platforms and strandlines ranging in elevation from 10 to 400 m over distances of 2 to 20 km from the fault the elevation of the terraces inner edges was estimated at 172 sites with an error of 5m this data set contains a precise description of the uplift and flexure of 10 different palaeohorizontal lines with respect to the present sea level to date the deformation we correlate the corinth terraces with late pleistocene oxygen isotope stages of high sea level stands and with global sea level fluctuations using a thick elastic plate model consistent with our current understanding of the earthquake cycle and a boundary element technique we reproduce the geometry of the shorelines to constrain both mechanical parameters and the slip on the fault we show that the seismogenic layer behaves over the long term as if its elastic modulus were reduced by a factor of about 1000 all the terraces are fitted for fault slip increasing in proportion to terrace age and the component of regional uplift is found to be less than 0 3 mm yr 1 the best fits give a slip rate of 11 3 mm yr 1 on the main rift bounding fault over the last 350 kyr other geological and morphologic information allows us to estimate the total age of the main fault 1 ma and to examine the mechanical evolution of the corinth rift the minimum observed sediment thickness in the gulf places an extreme check on the results of the modelling and a lower bound on slip rate of 6 7 mm yr 1 40 per cent less than estimated with modelling even this slip rate is nearly 10 times higher than for comparable features in most of the aegean and elsewhere in the world at a larger scale the spacing and asymmetry of the rift systems in the aegean suggest strain localization in the upper mantle with slow extension starting 15 myr ago or earlier the more recent 1 myr rapid phase of rifting in corinth partly reactivated this earlier phase of extension the younger faulting in corinth appears to result from its present location in the inhomogeneous stress field process zone of the south westward propagating tip of the southern branch of the north anatolian fault we extend these relations to propose a mechanical model for the late cenozoic evolution of the aegean as the arabia europe collision progressed in eastern turkey it caused anatolia to move to the west and the north anatolian fault to propagate into the aegean where the early slow extension started to be modified about 5 ma ago the process of propagation dramatically increased the activity of some but not all of the earlier rifts the model we present is compatible with tectonic observations as well as with the seismicity the palaeomagnetic rotations and the displacement field now observed with gps and slr

present day dynamics of the aegean region a model analysis of the horizontal pattern of stress and deformation in order to gain quantitative insight into the forces that control the present day stress field and pattern of horizontal motions in the aegean region we adopt a forward model approach mechanisms that have been proposed to explain the present day tectonics are represented to first approximation in terms of the expected force distributions on the basis of a thin elastic shell representation of the aegean lithosphere we then calculate the stress field and displacements associated with these force sets and compare the results with observations of the state of stress based on geological studies of fault kinematics strain as expressed by earthquake focal mechanisms and horizontal motions measured by means of satellite geodesy the two most commonly cited mechanisms suggested to control the aegean tectonics 1 the push exerted by the westward moving anatolian block and 2 forces associated with the hellenic subduction zone are first analyzed separately it is found that the westward anatolian push alone does not explain the observed prevalence of tensional stress this is also expressed in a mismatch between the displacements computed to result from the westward push and the observed horizontal velocities regarding the forces on the aegean overriding margin we find that a model with outward pulling forces of uniform magnitude acting normal to the arc from the sw peloponnese to rhodes yields a stress field that matches the observed pattern of tension to a large extent this distribution of forces is consistent with the notion of gravitational spreading of the aegean lithosphere the pattern of seismic strain of the overriding margin may evidence the occurrence of a small additional resistive force although the prevalence of tension thus appears due mainly to the subduction related forces other aspects of the stress field and also the pattern of horizontal motions indicate that these forces act in combination with westward push our model results allow us to address the relation between the forces experienced by the upper plate and the kinematics of subduction not just in terms of a vertical cross section but also by taking into account the along arc dimension

brine pool deposition for the zn pb cu massive sulphide deposits of the bathurst mining camp new brunswick canada i comparisons with the iberian pyrite belt abstract the ordovician zn pb cu massive sulphide ore deposits of the bathurst mining camp share many features with those of the devonian carboniferous iberian pyrite belt particularly the tendency to large size tonnage and metal content shape as far as can be determined after allowing for deformation metal content particularly fe cu pb zn and sn mineral assemblages pyrite arsenopyrite pyrrhotite and lack or rarity of sulphates sulphide textures particularly framboidal pyrite lack of chimney structures and rubble mounds irregular metal or mineral zoning and the low degree of zone refining compared to hokuroku ores the major differences between the provinces are the lack of vent complexes and the presence of sn cu ores in the iberian pyrite belt there are also similarities in the geological setting of the two camps both lie within continental terranes undergoing arc continent and continent continent collision and in each case massive sulphide mineralisation followed ophiolite obduction the ore deposits are associated with bimodal volcanic rocks derived from morb and continental crust and marine shales and mineralisation was locally accompanied or followed by deposition of iron formations fluid inclusion data from veins in stockworks from at least six of the iberian massive sulphide deposits point to sulphide deposition having taken place in basins containing mostly spent saline ore forming fluids brine pools and it is suggested that most of the major features of the bathurst deposits can be explained by similar processes the proposed model is largely independent of ocean sulphate and o 2 content whereas low values of each are requisites for the current spreading plume model of sulphide deposition in the bathurst camp

eastern mediterranean tectonics and tsunami hazard inferred from the ad 365 earthquake historical accounts describe an earthquake and tsunami on 21 july ad 365 that destroyed cities and drowned thousands of people in coastal regions from the nile delta to modern day dubrovnik the location and tectonic setting of this earthquake have been uncertain until now here we present evidence from radiocarbon data and field observations that western crete was lifted above sea level by up to 10 m synchronously with the ad 365 earthquake the distribution of uplift combined with observations of present day seismicity suggest that this earthquake occurred not on the subduction interface beneath crete but on a fault dipping at about 30 within the overriding plate calculations of tsunami propagation show that the uplift of the sea floor associated with such an earthquake would have generated a damaging tsunami through much of the eastern mediterranean measurement of the present rate of crustal shortening near crete yields an estimate of 5 000 yr for the repeat time of tsunamigenic events on this single fault in western crete but if the same process takes place along the entire hellenic subduction zone such events may occur approximately once every 800 yr in the year ad 365 an earthquake and tsunami destroyed much of the eastern mediterranean coastal regions the distribution of uplift at the time suggests that the earthquake occurred on a fault within the overriding plate at the subduction zone beneath crete and not on the subduction interface itself

subsea floor replacement in volcanic hosted massive sulfide deposits abstract recent research on volcanic hosted massive sulfide vms deposits indicates that syngenetic subsea floor replacement ores form an important component of many deposits in the context of vms deposits subsea floor replacement can be defined as the syn volcanic formation of sulfide minerals within pre existing volcanic or sedimentary deposits by infiltration and precipitation in open spaces fractures inter and intra granular porosity as well as replacement of solid materials there are five criteria for distinguishing subsea floor replacement in massive sulfide deposits 1 mineralized intervals are enclosed within rapidly emplaced volcanic or sedimentary facies lavas intrusions subaqueous mass flow deposits pyroclastic fallout 2 relics of the host facies occur within the mineral deposit 3 replacement fronts occur between the mineral deposit and the host lithofacies 4 the mineral deposit is discordant to bedding and 5 strong hydrothermal alteration continues into the hanging wall without an abrupt break in intensity criteria 1 3 are diagnostic of replacement whereas criteria 4 and 5 may suggest replacement but are not alone diagnostic because clastic sulfide ores contain accessory rock fragments collected by the parent sediment gravity flow s during transport criteria 2 can only be applied to massive semi massive disseminated or vein style deposits and not clastic ores the spectrum of vms deposit types includes deposits that have accumulated largely subsea floor and others in which sedimentation and volcanism were synchronous with hydrothermal activity and precipitation of sulfides occurred at and below the sea floor over the life of the hydrothermal system deposits that formed largely subsea floor are mainly hosted by syn eruptive or post eruptive volcaniclastic facies gravity flow deposits water settled fall autoclastic breccia however some subsea floor replacement vms deposits are hosted by lavas and syn volcanic intrusions sills domes cryptodomes burial of sea floor massive sulfide by lavas or sediment gravity flow deposits can interrupt sea floor mineralization and promote subsea floor replacement and zone refining the distance below the sea floor at which infiltration and replacement took place is rarely well constrained with published estimates ranging from less than 1 to more than 500 m but mainly in the range 10 200 m the upper few tens to hundreds of metres in the volcano sedimentary pile are the favoured position for replacement as clastic facies are wet porous and poorly consolidated in this zone and at greater depths become progressively more compacted dewatered altered and less amenable to large scale infiltration and replacement by hydrothermal fluids furthermore sustained mixing between the upwelling hydrothermal fluid and cold seawater is regarded as a major cause of sulfide precipitation in vms systems and this mixing process generally becomes less effective with increasing depth in the volcanic pile the relative importance of subsea floor replacement in vms systems is related principally to four factors the permeability and porosity patterns of host lithofacies sedimentation rate the relative ease of replacement of host lithofacies especially glassy materials and early formed alteration minerals during hydrothermal attack and physiochemical characteristics of the hydrothermal fluid

late holocene sea level evolution of paros island cyclades greece abstract relative sea level rsl reconstructions are essential to answer a variety of scientific questions ranging from the investigation of crustal movements to the calibration of earth rheology models and ice sheet reconstructions it is generally assumed that most cycladic islands aegean sea greece are affected by a gradual subsidence attributed to the crustal thinning and to hydro isostatic processes that accompanied the post glacial rise in sea level in this paper we produce new rsl data from sedimentary records on paros island we compare and contrast these rsl data with published data from the nearby island of naxos our results are further compared with sea level predictions from two different gia models in an attempt to better quantify the tectonic regime of the wider study area our results suggest average tectonic subsidence rates close to 1 0 0 4 mm yr since 5500 cal bp these rates are not linear in time and have increased since 2500 cal bp

normal faulting and crustal deformation alkyonides gulf and perachora peninsula eastern gulf of corinth rift greece geophysical structural geochronological and geomorphological data indicate that the psatha east alkyonides skinos and pisia faults are holocene active structures whereas the status of the west alkyonides strava perachora and loutraki faults is less certain we see no evidence for significant lateral surface fault growth new data for late pleistocene footwall uplift of the psatha fault are comparable with previously estimated holocene rates pre holocene stratigraphic sequences in the alkyonides gulf allow calculation of vertical displacement on the skinos fault of 1 42 1 60 km over a period of 0 6 ma previous palaeoseismological studies indicate comparable displacement rates extrapolated to 0 61 2 20 ma whereas extrapolation of previous geodetic data indicate a range of 0 17 0 46 ma the latter is too short given the evidence of the stratigraphic record signifying either that these data may not be representative of longer term rates or that significant deformation has taken place elsewhere for example on offshore antithetic faults a case is established for uniform late quaternary post mis 7 uplift of the perachora peninsula at rates of c 0 2 0 3 mm a 1 the lack of regional tilting over perachora corinth isthmia is in marked contrast to the situation in the alkyonides megara basins to the east

surface sediment geochemistry and hydrothermal activity indicators in the dragon horn area on the southwest indian ridge abstract the fluids found in sulfide producing hydrothermal vents are rich in ore forming elements these elements usually precipitate as solid particles that are dispersed by the plumes and deposited as sediments around the hydrothermal field to assess how the geochemical features of such sediments may be used in seafloor sulfide exploration this study analyzed the surface sediment geochemistry in the dragon horn area on the southwest indian ridge the results indicate that the sediments are mainly composed of pelagic material basalt and ultramafic debris mn fe oxyhydroxides and mn oxides hydrothermal components the debris content in this area is lower than that in sediments found at fast and medium spreading mid ocean ridges with relatively high amounts of ultramafic components indicating that ultramafic rock outcrops are present in the study area precipitated hydrothermal elements in the sediments exhibit zonation in the spatial distributions of zn cu fe and mn the sediments proximal to the hydrothermal field display high cu zn and fe contents and low mn contents hydrothermal cu and zn phases occurred within a limited range of the hydrothermal field and zn was found to precipitate earlier than cu during dispersal from the plume hydrothermal fe distributed similarly with cu spatially but with a larger dispersion distance hydrothermal mn was able to migrate beyond the ridge valley to precipitate in the ridge flank sediments two hydrothermal cu and zn anomalies were identified on the south ridge flanks which suggest the presence of undiscovered hydrothermal field the sediments in the study area are additionally characterized by relatively low mn contents and high fe mn molar ratios the relatively reducing environment of the plume may facilitate the migration of hydrothermal mn over large distances which probably accounts for the lower mn contents in the sediments the cu cu fe molar ratio model was proposed to identify mafic and ultramafic related hydrothermal field the low cu fe molar ratios and ree characteristics of the sediments suggest that ultramafic rocks are likely not the only source of the ore forming element for hydrothermal mineralization low temperature diffuse flow on the ridge flanks of the study area probably results from serpentinization of ultramafic rocks

formation on the sea floor of the hellyer volcanogenic massive sulfide deposit new fluid inclusion data from the stockwork veins beneath the hellyer orebody a relatively undeformed late cambrian polymetallic volcanogenic massive sulfide deposit allow semiquantitative modeling of the behavior of the ore fluids on the sea floor and the manner of growth of the massive sulfide the earliest cool fluids may have been denser than seawater and ponded in a basin identified by sedimentological and structural studies subsequent vent fluids buoyant with respect to the brine pool and subsequently at higher temperature with respect to seawater mixed with the cooler brine during and after filling the basin to the level of its lowest outlet density inhomogeneities within the brine pool were reduced by double diffusive convection across the brine seawater interface and internal boundaries and mixing by currents within the brine pool estimates of likely temperatures and salinities in the brine pool for the first main mineralization stage avg 200 c 11 wt salinity assuming a steady or quasisteady state had been established and using volume fluxes similar to those observed in modern oceans indicate temperatures 100 c sulfides mostly pyrite sphalerite and galena precipitated from the vent fluids after mixing with cooler basin fluid settled from the gravity current to the basin floor a pattern that would have continued whether or not a true steady state was reached if the early fluids were buoyant in seawater they ponded after mixing forming a hybrid brine pool that would have required longer periods to homogenize at the peak temperature 300 c and volume flux the salinity of the vent fluids fell to 7 5 wt percent but the flow paths would have been maintained unless the brine pool had been drained at this time that part of the massive sulfide body over the vent the cu core grew by dilatational veining together with leaching cavity infilling replacement and recrystallization chalcopyrite was deposited both in the cu core and probably at the same time in a layer over the flanking massive sulfide in the final stage as temperature fell and salinity rose avg 250 c 11 wt salinity the fluid oxidation potential increased so that barite precipitation dominated resulting in a formation of a discontinuous barite rich cap over the massive sulfide the brine pool model explains several features of the hellyer ore that differ from those of the ores of the hokuroko basin namely the large metal content high zn cu ratio low aspect ratio absence of chimney fragments presence of mineral banding and high barite sulfur isotope values features seen in many other massive sulfide orebodies

linear elastic fracture mechanics explains the past and present evolution of the aegean abstract geologically the deformation in the anatolian aegean region has been dominated by two processes the propagation of the north anatolian fault associated with the extrusion of the anatolian plateau and the north south stretching of the aegean we model gps data in the context of this understanding localised deformation zones are represented by dislocation elements which extend from the base of the lithosphere to the locking depth at the base of the seismogenic layer unlike other gps interpretations our models incorporate geological and seismological constraints to provide a robust description of the present day deformation of the anatolian aegean region we then show that the present day deformation observed by gps today is consistent with the continuation of the geological processes that started in the tertiary our approach is also consistent with the lithosphere preserving long term elastic strength and with the concepts of linear elastic fracture mechanics applying at a large scale

archaeology of the continental shelf marine resources submerged landscapes and underwater archaeology we provide a critical review of the evidence for the long term use of marine resources and coastal environments in human evolution and later development we emphasise the importance of the coastal archaeological record in understanding patterns of human settlement and dispersal and draw attention to the large potential biases introduced by the destructive or obscuring effects of pleistocene sea level change we note that lowered sea levels have been the norm for most of the pleistocene and that periods of high sea level have been too short lived to provide other than a fragmentary coastal record and one that is beset with ambiguities and uncertainties we examine the geological processes of coastal uplift and underwater preservation that may help to mitigate these biases coastlines elevated by isostatic and tectonic processes or with very steep offshore drop offs at plate boundaries are important in providing a potential window into coastal landscapes and archaeology formed during periods of lowered sea level however we conclude that the opportunities afforded by these geological factors are too limited to obviate the need for underwater exploration we review the evidence now available from submerged landscapes across the africa eurasia interface from the atlantic coastlines of northwest europe to the southern red sea we show that geomorphological conditions for the preservation of archaeological and palaeoenvironmental data are commonly present that much material has already been discovered and that new techniques technologies and projects are providing the momentum for a rapidly expanding field of investigation the results do not simply add to what we already know from sites on land but are likely to produce qualitatively different evidence for coastal adaptations and landscapes that have no analogue on present day coastlines we note the strong probability that many coastal landscapes exposed at lowered sea level provided relatively fertile and productive refugia for plants land mammals and humans at a time when increased aridity would have reduced or deterred hinterland occupation we conclude that underwater investigation is essential if hypotheses of early human adaptation and dispersal are to be fully tested

the 12 june 2017 mw 6 3 lesvos island aegean sea earthquake slip model and directivity estimated with finite fault inversion abstract on 12 june 2017 utc 12 28 38 26 a magnitude mw 6 3 earthquake occurred offshore lesvos island in se aegean sea which was widely felt caused 1 fatality and partially ruined the village of vrisa on the south eastern coast of the island i invert broad band and strong motion waveforms from regional stations to obtain the source model and the distribution of slip onto the fault plane the hypocentre is located at a depth of 7 km in the upper crust the mainshock ruptured a wnw ese striking sw dipping normal fault projecting offshore and bounding the lesvos basin the strongest and most aftershocks clustered away from the hypocentre at the eastern edge of the activated area this cluster indicates the activation of a different fault segment exhibiting sinistral strike slip motions along a plane striking wnw ese the slip of the mainshock is confined in a single large asperity wnw from the hypocentre with dimensions 20 km 10 km along fault strike and dip respectively the average slip of the asperity is 50 cm and the peak slip is 1 m the rupture propagated unilaterally towards wnw to the coastline of lesvos island at a relatively high speed 3 1 km s the imaged slip model and forward modelling was used to calculate peak ground velocities pgvs in the near field the damage pattern produced by this earthquake especially in the village of vrisa is compatible with the combined effect of rupture directivity proximity to the slip patch and the fault edge spectral content of motions and local site conditions

late pleistocene unconformity in the gulf of kavalla northern aegean greece abstract a 147 cm core from the gulf of kavalla on the northern aegean shelf displays two different lithologies separated by an erosional contact the upper part 0 128 cm consists of clayey silt to silty clay grading into silty sand and represents a neritic to nearshore marine environment the lower section 128 147 cm is a stiff calcareous mudstone with scattered microcrystalline calcite nodules and probably represents part of a subaerial soil horizon b ca seismic data indicate that at this location the unconformity between the late glacial subaerial surface and the overlying post glacial transgressive deposits occurs at a depth of 150 cm and has apparently been sampled by the core

global comparisons of volcanic associated massive sulphide districts although volcanic associated massive sulphide vms deposits have been studied extensively the geodynamic processes that control their genesis location and timing remain poorly understood compar

zn pb cu massive sulfide deposits brine pool types occur in collisional orogens black smoker types occur in backarc and or arc basins volcanic hosted massive sulfide deposits of zn pb cu type were derived either from seawater dominated buoyant fluids that built mounds on the seafloor e g the ores of the hokuroku basin japan or from saline fluids that reversed buoyancy on mixing with seawater and filled basins on the seafloor e g several ores of the iberian pyrite belt and the mount read province in tasmania the hokuroku ores formed above subduction zones during protracted periods of regional extension but both the iberian pyrite belt and the mount read province formed under extensional stress during continent continent iberia or arc continent mount read collision and orogenesis in the iberian pyrite belt oblique convergence resulted in transcurrent faulting and this may also be the case for the mount read province transcurrent faulting may have allowed easy vertical access for the ore related magmas some of which were sourced in the asthenosphere as well as the blueschist and eclogitic facies emplaced in adjacent terrains and possibly also saline fluids exsolved from the magmas

shallow structure and recent evolution of the aegean sea a synthesis based on continuous reflection profiles abstract a dense grid of continuous seismic reflection profiles partly calibrated with drilling results has allowed construction of a structural outline of the entire aegean sea in the north aegean we observe a clear difference between the thickly sedimented northern margin basins and the steep slopes of the trough margin of the southern north aegean the trough itself comprises a series of separate tectonic depressions resulting from an apparent transtensional motion the central aegean consists of a complex tectonic puzzle caused by the prevailing extension incipient strike slip faulting sub parallel to the north aegean trough trend may however affect its eastern anatolian domain three main structural areas characterize the southern aegean comparable structural directions cut across this chiefly extensional basin but one fault system may be prevailing over the others depending on the area the central cretan sea results from the interaction of at least two distinct extensions these were superimposed on previous mostly e w structural trends generated during the inception of the southern hellenic subduction and led to the present day predominant sw ne trending extension as a hypothesis we propose that the overall late miocene present evolution of the aegean sea is directly dependent on two geodynamic processes to the southeast of the area collision between arabia and turkey leads to the lateral westward expulsion of the aegean continental crust and to the west hellenic subduction is still active

petrogenesis of the rambler rhyolite formation controls on the ming vms deposit and geodynamic implications for the taconic seaway newfoundland appalachians canada the ming cu zn ag au volcanogenic massive sulfide vms deposit is hosted by the upper cambrian lower ordovician rambler rhyolite formation which consists of a folded northeast plunging felsic dome complex developed in the uppermost segment of the obducted supra subduction baie verte oceanic tract in the north central newfoundland appalachians the deposit is overlain by interstratified mafic volcanic flows and volcaniclastic rocks of the snooks arm group the upper 1 km of the rambler rhyolite formation consists of a coherent felsic lithofacies at its base overlain by a quartz bearing volcaniclastic dominated lithofacies units 1 2 and 1 3 geochemically these rocks are light rare earth element lree and large ion lithophile element lile enriched la yb pn 4 20 th 2 58 4 05 ppm and high field strength element hfse depleted y 5 64 6 59 ppm rhyodacite with calk alkalic affinities th yb 2 zr y 7 the last pulse of felsic volcanism unit 1 3 is intimately associated with the massive sulfide lenses and has fi and fii type rhyolite signatures high la yb ratios commonly attributed to deep 30 km crustal melting the end t values of the rhyolites range from 2 5 to 1 3 indicating the rocks were influenced by crustal material a 10 percent batch partial melt of a garnet amphibole metamorphosed normal mid oceanic ridge basalt n morb and island arc tholeiite iat crustal material can generate a melt similar to the felsic rocks hosting the ming deposit however the iat reproduces much better the absolute abundances of lile th sr hfse nb zr y and middle rare earth elements mree of the felsic rocks it is interpreted that the felsic melt came from melting of a subducted slab with iat affinity thus explaining the depth of melt generation and fi fii signatures of the felsic rocks moreover the slab derived siliceous melt may also have contributed magmatophile elements for example ag au se te sn sb hg into the hydrothermal system once it had reached near surface depths and may explain the epithermal suite element enrichment in the ming deposit this study shows that strongly fractionated felsic volcanic rocks associated with boninites such as those associated with the ming vms deposit can be important hosts for precious metal enriched vms and may be as prospective as tholeiitic felsic volcanic sequences for example fiii fiv type rhyolite low la yb ratios the base of the snooks arm group is comprised of spatially restricted sulfide bearing mafic breccia overlain by a regionally extensive sedimentary sequence end t 3 1 to 5 5 which is in turn overlain by interstratified high mg basalt end t 1 6 th enriched back arc basin basalt babb enriched mid oceanic ridge basalt e morb end t 6 6 and lree enriched low ti tholeiitic tuffs end t 0 5 four generations of mafic to intermediate dikes and sills cross cut the rambler rhyolite formation and share similar geochemical characteristics to the extrusive rocks of the snooks arm group suggesting comagmatic relationships the combination of variations in nb yb th yb and end t values within and between units suggest melts derived from depleted to enriched mantle material with melts synchronously generated by both slab metasomatized mantle wedge and upwelling back arc asthenosphere

seismic stratigraphy and quaternary sedimentary history of the northeast aegean sea abstract seismic profiles show that the upper quaternary recent stratigraphic architecture of the ne aegean sea is characterized by several vertically stacked depositional sequences which are developed within three ne sw trending basins the depositional sequences are separated from one another by prominent shelf crossing unconformities formed during periods of falling and low sea level and reworked further during the subsequent sea level rise by shoreface erosion each depositional sequence consists of a lower mainly parallel stratified subunit and an upper oblique to sigmoid oblique prograded subunit the lower subunit represents hemipelagic and prodeltaic deposition of the transgressive and early highstand systems tracts the upper subunit represents deltas of the forced regressive systems tract the chronology of the depositional sequences is constrained by radiocarbon and u th dates on cores an average sedimentation rate of 30 cm ka is calculated for basinal muds of the region correlations with global sea level curves based on oxygen isotope stratigraphy reveal that the seaward prograded delta sequences developed on a rapidly subsiding shelf during successive glacio eustatic sea level falls associated with late quaternary glaciations a set of paleogeographical maps shows changing basin configuration since 330 ka volumes of the depositional sequences compare well with the volumes of sediment estimated to have been eroded from the incised valleys of the tuzla karamenderes and dumbek rivers draining the biga peninsula

late quaternary tectonic and sedimentary history of outer izmir and candarli bays western turkey abstract air gun and 3 5 khz seismic profiles from the eastern aegean sea off turkey show that the continental shelf of outer izmir and candarli bays is formed by several superimposed deltaic sequences during times of lowered sea level associated with late quaternary glaciations deltas prograded seaward more than 60 km from their present positions foreset progradation ceased with the rise of sea level in interglacial and post glacial times and deltas were reestablished far inland in drowned river valleys these major transgressions resulted in unconformities within the superimposed prograded delta sequences the most recent three unconformities are correlated with the beginning of oxygen isotope stages 5 3 and 1 and provide chronostratigraphic markers for a detailed analysis of sedimentation patterns in the late quaternary the coastal shelf and basins are subsiding at an average rate of about 1 m per 1000 years this tectonic subsidence manifests itself as widespread normal block faulting which can be related to the pre miocene structural framework of the region

the impacts of sea level changes during latest pleistocene and holocene times on the morphology of the ionian and aegean seas se alpine europe abstract the tentative coastline configuration in the ionian and aegean seas in three late pleistocene holocene time slices is given based on the global eustatic sea level curve in combination with local geological and geoarcheological data at lowstand stage 2 21 500 cal yr bp years before present sea level 120 m extensive shelves existed in the northern aegean sea and to a second degree in the eastern aegean sea and in the northern and central parts of the ionian sea many islands were connected with each other and with the mainland a great part of the periphery of gulfs that have an entrance less than 120 m deep was subaerially exposed while in their central parts lakes were formed at 11 500 cal yr bp sea level 60 m the exposed shelf was much restricted most of the gulfs were overflowed by the advancing sea and only a few islands were still connected with the mainland finally at 8000 cal yr bp and onward the sea initially intruded the lowlands and the gulfs but the subsequent sediment input by the rivers regressed the sea to its present position thus many human settlements and old cities that were maritime during hellenistic or older times are now a few to tens of kilometers inland

crustal block movements from holocene shorelines crete and antikythira greece abstract marks of several shorelines left by sea level stands during the last 4000 yrs occur along the coasts of the islands of crete and antikythira in this area recent movements of the earth s crust were identified by using a systematic survey based on multidisciplinary analyses strengthened by 60 radiometric datings between 4000 and 1700 yr b p a block of lithosphere a about 150 km long fig 10 which included antikythira and the levka mountains in crete underwent a series of ten rapid subsidences from 10 to 25 cm each time without noticeable tilting these movements ended about 1 530 40 yr b p a further block of lithosphere b approximately 200 km long was then uplifted about 10 m and inclined northeastwards in a single event block b includes block a and extends 50 km further eastwards beyond the ida mountains as far as the iraklion sedimentary basin the tectonic movements were preceded by vertically reversed displacements of short duration on at least three occasions if the a block subsidences can be ascribed to gravitational forces then the b block uplift suggests a cause that originated at depth crustal consumption and elastic rebound to the east of the ierapetra graben the sitian peninsula appears to belong to a block of lithosphere c affected by a northeast tilting and separated by an active fault from the crustal block of khrisi koufonisi

palaeoenvironmental evolution and sea level changes in the coastal area of ne lemnos island greece during the holocene abstract the study area is located on the northeastern coast of lemnos island north aegean sea 40 2 30 n 25 00 00 e it covers the archaeological settlement of hephestia located in the purnia gulf and the coastal area of alyki lagoon reconstruction of the palaeogeography used palaeoenvironment data delivered from foraminifera and sea level changes providing archeological data about the presence of a potential harbour in the area geomorphological mapping as well as sedimentological and micropalaeontological studies of the holocene coastal deposits were conducted four boreholes were drilled from the alyki lagoon reaching 2 5 m to 11 m at the deepest and two from hephestia area reaching a depth of 6 m twenty four samples were dated using the ams radiocarbon method providing a chronology of the sedimentary units the calculated age from the boreholes provides dates from 7050 cal bp to 990 cal bp there was a constant sea level rise during the last 7000 cal bp in the study area results from the model of lambeck sea level curve and sea level index point from hephestia and alyki show a vertical difference of 0 5 1 5 m below sea level the foraminiferal fauna analysis shows the development of shallow marine conditions with fresh water influx during 7000 4000 cal bp and a temporary lagoon environment with fluctuations to shallow bay environment from 4000 to 990 cal bp

geodetic determination of the kinematics of central greece with respect to europe implications for eastern mediterranean tectonics we use a new satellite laser ranging global positioning system slr gps solution at seven sites in anatolia and aegea to obtain a better definition of the extrusion motion of the anatolian aegean block with respect to europe we show that this motion can be described in a first approximation by a counterclockwise rotation which transfers most of the motion of arabia to anatolia we combine 78 displacement vectors obtained at common points of two triangulation nets measured in central greece in 1895 and 1975 with the slr gps measurements to compute the velocity field over greece with respect to europe these measurements indicate that central greece is a zone of extension between the anatolian aegean counterclockwise rotation to the south and the northern greece clockwise rotation to the north this extension is principally localized within the gulf of corinth to the east but is distributed to the west we then extrapolate this velocity field to the whole aegea and western anatolia using recently published gps results as well as the slr results the narrow dextral north anatolian fault which limits the velocity field to the north progressively gives way to a much wider boundary zone where extension becomes dominant we show that the collision between the mediterranean ridge and africa began 3 6 ma and we describe the modifications that this collision has produced on the kinematic pattern both in aegea and on the mediterranean ridge