heat flow in the baltic shield results of the lithospheric geothermal modelling abstract the results of heat flow measurements performed within the baltic shield and in its closest neighbourhood are reviewed the regional distribution of the heat flow density is presented as a heat flow map the characteristic heat flow density amounts to 35 40 mw m 2 and is notably smaller than heat flow in the surrounding areas the radiogenic heat production within the crust contributes to the observed surface heat flow by about 15 20 mw m 2 this permits to estimate the moho heat flow in the most stable parts of the shield to about 20 mw m 2 and over 25 30 mw m 2 in the surrounding platform to the south and east relatively low moho temperatures of 350 500 c characterize the crust mantle boundary of the shield increasing to 600 700 c beneath the shield margins the thermal thickness of the lithosphere of the shield can attain more than 200 km

earthquakes in northern europe in 1375 1989 abstract an updated version of the catalogue of earthquakes in northern europe is presented it comprises events inside a region window of about 55 80 n and 10 w 45 e covering a 615 year period from 1375 to 1989 the data have been compiled using all the available historical publications catalogues studies and reports of the region and for events from 1984 to 1989 a regional seismic parameter database maintained by the institute of seismology of the university of helsinki the number of events exceeds 5200 of which more than 40 have been registered since 1980 the huge increase of event reports is the result of the installation of new high frequency networks for microearthquake studies and the upgrade of the seismic instrumentation because of the different degree of accuracy and homogeneity of the parameter data the events were divided into historical 1375 1964 and instrumental 1965 1989 datasets the source parameters are mainly macroseismic for historical events and obtained by iterative location procedure for instrumental data by assuming internal homogeneity between the different regional magnitude scales we estimated the catalogue to be complete for events with magnitude 4 5 since the 1880 s magnitude 4 0 4 4 since the 1940 s and magnitude 3 5 3 9 since the 1970 s although the distribution of seismicity exhibits similar patterns in both datasets the clustering of epicenters and offshore seismicity is more distinct in the instrumental period the occurrence of the greatest events can be seen more clearly in the historical data the earthquake epicenters are concentrated in the geologically younger tectonic provinces in the western part of the region and follow with some exceptions the tectonic fracture and fault zones in the fennoscandian area 80 of the earthquakes occurred in the upper 20 km of the earth s crust the deepest epicenters are in the southwestern corner of the region where the crust is thinnest

thermomechanical lithospheric structure of the central fennoscandian shield abstract the deep seismic sounding dss profiles baltic including its southern continuation the sovetsk kohtla jarve skj profile sveka the northern part of babel polar fennia and pechenga kovdor kostomuksha were used in studying the present day thermomechanical structure of the central fennoscandian shield these profiles are located in different tectonic units which represent different stages in precambrian crustal and lithospheric growth first present day geotherms were constructed for several points along the dss profiles successively strength envelopes were calculated using the obtained geotherms and rheological flow laws variations in strain rate were also considered in the computations of the strength envelopes the integrated crustal and lithospheric strengths the thicknesses of the mechanically strong crust msc and mechanically strong lithosphere msl and the rheological thickness of the lithosphere were derived from these strength envelopes the obtained mechanical structures for different regions were analysed and compared with other geophysical data e g seismicity depth and isotherm depth distributions the rheological results show lateral variations in the lithospheric strength reflecting the geometry of the lithosphere and following roughly the same trend as the geochronological development of the fennoscandian shield the mechanical structure shows distinct decoupling of the weak lower crust and the strong upper mantle particularly with a wet rheology this decoupling interrupts the transmission of the differential stress from the brittle upper crust to the ductile lower crust and through it to the mantle lithosphere the weak lower crustal layer is also detected with a dry rheology in the svecofennian area whereas in the archaean side it is not distinct the assumed frictional transition temperature of 350 c varies between the depths of 25 and 44 km with an average value of 35 km this is in good agreement with the observed focal depth limit of 31 km consequently it seems that the velocity weakening velocity strengthening explains best the real lower boundary of seismicity

the role of radiogenic heat production in the thermal evolution of a proterozoic granulite facies orogenic belt eastern ghats indian shield abstract the eastern ghats belt egb is a deeply eroded proterozoic orogenic belt juxtaposed against the archaean dharwar bastar singhbhum cratons in the indian shield the tectono metamorphic history of this belt is broadly similar to the grenvillian orogenic belts the egb exposes dominantly the granulite facies rocks such as charnockites khondalites and migmatitic gneisses with less abundant intermediate to mafic granulites the granulites are intruded by small plutons of granites syenites and anorthosites the northern and southern parts of the belt negb and segb have distinct crustal histories but 1600 1000 550 ma old tectono metamorphic events are common to both the belts in this research we attempt to understand the present day and past thermal state of this orogen on the basis of our radioelement k u and th measurements at 562 sites using in situ gamma ray spectrometry with other geological and geophysical constraints the dominant rock types of the negb and segb have similar radioelement abundances 3 k 3 ppm u and 30 ppm th and heat production heat production of charnockites gneisses khondalites and intermediate granulites of the negb is 2 9 2 8 2 9 and 1 1 w m 3 respectively in the segb they are 2 7 2 5 2 8 and 0 6 w m 3 respectively and the mafic granulites are the lowest in heat production 0 3 w m 3 on the basis of the heat production data and crustal petrologic models we show that the crustal contribution of the negb and segb is 54 and 45 mw m 2 respectively which are broadly in good agreement with the available surface heat flow data thermal models of the present day egb crust indicate that the temperature at the moho is 550 c radioelements and heat production of the eastern ghats granulites are higher than the other granulite belts in the indian shield the crustal radiogenic heat contribution and moho temperatures of the egb are higher than the adjoining archaean cratons this could also be responsible for the development of inverted metamorphic isograds in the tectonic boundary between the egb and the adjoining cratons during a collisional orogenic event at about 550 ma ago

heat flow map of northern and central parts of the fennoscandian shield based on geochemical surveys of heat producing elements abstract the heat flow heat production q a relationship is a useful tool in geothermal research and it has been widely used for delineating geothermal provinces and determining characteristic parameters of heat production in the continental crust in this study a simple but rarely used technique of utilizing the heat flow heat production relationship is discussed in central and northern parts of the fennoscandian shield extensive geochemical surveys have produced 1483 samples taken from glacial till with a sampling density of 1 sample 300 km 2 heat production values determined from u th and k concentrations in these samples were used to calculate a map of heat flow density a previously determined q a relationship q 15 8 10 8 a was applied the compiled map covers all finland northern sweden and northern norway about 35 of the exposed shield area in fennoscandia heat flow density and heat production increase with decreasing geological age and correlate with granitoid types the calculated heat flow density values on the map were controlled with 12 drill hole measurements not used in calculating the applied q a regression line nine of them are from previously unpublished data from the finnish part of the shield the agreement with drill hole measurements and the geochemical estimate is reasonable although not perfect in all cases the differences can be attributed to anomalous vertical variation in heat production reliability of the applied q a plot reliability of till geochemistry in bedrock studies convective groundwater disturbances or local structural effects the calculated heat flow map can be used as a data set supplementing drill hole measurements to determine representative values of heat flow density in areas with low numbers of drill hole measurements

the variation of heat generation density and seismic velocity with rock type in the continental lithosphere abstract the petrophysical properties radioactive heat generation compressional wave velocity and density are related to rock type in crystalline rocks the cation fraction in the rock forming minerals is applied to determine the relationships quantitatively heat generation exhibits considerable variation with rock type as well as with the geologic age of the rocks therefore the relation between heat generation and rock type has been split into a relation for phanerozoic rocks and another for precambrian rocks which exhibit significantly lower heat generation only 1 3 of that of phanerozoic rocks the interrelations between the petrophysical properties are applied to fennoscandia precambrian terrane and southern bavaria northern alpine foreland phanerozoic rocks to estimate the heat generation by radioactivity in the crust and the heat flow density from the upper mantle

ostracods from a marmara sea lagoon turkey as tsunami indicators abstract a 352 cm long sediment core from hersek lagoon gulf of izmit was investigated for its ostracod species composition in order to evaluate the potential of ostracods to detect tsunami deposits in coastal environments the gulf of izmit is the eastern bay of the marmara sea which is tectonically controlled by the north anatolian fault ostracod shells are rare in the lower third of the core which probably represents a coastal wetland environment according to radiocarbon dating of terrestrial plant remains this unit was deposited between ad 500 and ad 800 above ostracod shells are abundant and dominantly monospecific composed almost exclusively of the widespread brackish water ostracod cyprideis torosa this almost monospecific occurrence indicates the establishment and maintenance of the hersek lagoon after ad 800 three distinct layers of mollusc shells and fragments contain ostracod shells of marine and to a lesser extent non marine origin in addition to those of c torosa the shell layers are further characterized by significant maxima in total ostracod shell numbers the high concentration of ostracod shells the higher species numbers and the mixture of marine lagoonal and non marine ostracod shells shows that shell layers were formed as high energy deposits resulting from tsunamis or large storms in the marmara sea the partial occurrence of non marine ostracod shells in the shell layers possibly indicates that tsunamis with extensive run ups and significant backwash flows caused the high energy deposits rather than large storms the investigated sediments show that lagoonal ostracods can serve as good proxies for tsunamis or large storms through significant variations in total shell numbers species numbers and the mixing of shells of different origin

heat production in an archean crustal profile and implications for heat flow and mobilization of heat producing elements we have measured concentrations of heat producing elements th u and k in 58 samples representative of the main lithologies in a 100 km transect of the superior province of the canadian shield from the michipicoten wawa greenstone belt near wawa ontario through a domal gneiss terrane of amphibolite grade to the granulite belt of the kapuskasing structural zone near foleyet this transect has been interpreted as an oblique cross section through some 25 km of crust uplifted along a major thrust fault and thus provides an opportunity to examine in detail a continuous profile into deep continental crust of archean age mean heat production values for these terranes based on aereal distribution of major rock types and calculated from their th u and k concentrations are michipicoten greenstone belt 0 72 w m 3 wawa domal gneiss terrane amphibolite grade 1 37 w m 3 kapuskasing granulites 0 44 w m 3 among the silicic plutonic rocks tonalites granites and their derivative gneisses the relatively large variation in heat production correlates with modal abundances of accessory minerals including allanite sphene zircon and apatite we interpret these variations as primary pre metamorphic the relatively high weighted mean heat production of the domal gneiss terrane can be accounted for by the larger proportion there of late stage th u and k rich granitoid plutons these may have been derived from the underlying kapuskasing granulite terrane leaving it slightly depleted in heat producing elements transport of th u and k therefore could have taken place in silicate melts rather than in aqueous or carbonic metamorphic fluids this conclusion is supported by the lack of a statistically significant difference in heat production between tonalites tonalite gneisses and mafic rocks of amphibolite versus granulite grade the pre metamorphic radioactivity profile for this crustal section is likely to have been uniformly low with a mean heat production value less than 1 w m 3 this result is distinctly different from measured profiles in more silicic terranes which show decreasing heat production with depth this implies fundamental differences in crustal radioactivity distributions between granitic and more mafic terranes and may be an important factor in selective reactivation of lithologically different terranes possibly resulting in preferential stabilization of basic terranes in the geological record our results indicate that a previously determined apparently linear heat flow heat production relationship for the kapuskasing area does not relate to the distribution of heat production with depth low but significant heat production 0 4 0 5 w m 3 continues to lower crustal depths with no correlation to the depth parameter from the linear relationship this low heat production may be a minimum average granulite heat production and suggests that in general heat flow through the moho is 8 10 mw m 2 lower than the reduced heat flow calculated from the heat flow heat production regression

abrupt environmental changes within a late holocene lacustrine sequence south of the marmara sea lake manyas n w turkey possible links with seismic events abstract a coring campaign in lake manyas kus golu on the southern coast of the sea of marmara turkey has provided insights into basin infilling processes during the upper 11 metres of the sedimentary record combined sedimentary features between 5 and 4 m depth have been explained by a seismite a brittle mixed layer uniquely rich in seeds and ostracod valves was widely detected at 4 m downcore this has been interpreted as being the result of a seiche either through a salt inundation linked to a tsunami in the sea of marmara the large scale scenario or a local hydrothermal fluid discharge the small scale scenario ostracod valves which are usually not preserved in lake manyas sediment are either incorporated here as tsunami debris providing a spatially averaged snapshot of the regional assemblage or are locally preserved following a temporary geochemical hydrochemical change of the water of unknown duration but probably several decades the brittle mixed layer overlies cracks resulting from the direct effects of the seismic shock wave on slightly compacted sediment at around 964 cm depth palynological and particle size analyses indicate a change from backswamp to open lacustrine conditions the end of the backswamp has been correlated with a decrease in the level of the sea of marmara from 4000 to 3000 2800 yr ago uncal caused by regional tectonic movements an age depth model is presented based on two ams radiocarbon dates on the palynological detection of the end of the beysehir occupation phase 130 cm above the event and on maximal sedimentation accumulation rates obtained by radionuclide analyses the entire study sequence covers the last 4300 yr the paper examines the possibility of an early byzantine age for the seismic event this may have been the historical event at ad 460 that destroyed cyzicus the ancient erdek 20 km north of the lake and various villages in the interior and was felt widely in the then known world other possibilities include various local and regional events in that same period the early byzantine tectonic paroxysm and the large earthquake in ad 447 that affected the entire sea of marmara region

anthropogenic changes in the landscape of west java indonesia during historic times inferred from a sediment and pollen record from teluk banten palynological and charcoal analyses of shallow marine core 98 28 from the northern coastal area of west java provide a regional vegetation history during the last few centuries reliable chronostratigraphical control is provided by 210pb analyses and the occurrence of the 1883 krakatau ash tsunami layer as a time marker the results permit the distinction of four successive stages reflecting increased disturbance and land clearance with some evidence for the presence of deciduous lowland forests in the banten area during the early holocene the establishment of coconut and pine plantations and the severe loss of biodiversity in the last few decennia are also echoed in the pollen record the effect of the krakatau eruption was insignificant compared with human impact on vegetation in the banten area copyright 2004 john wiley sons ltd

heat flow gravity and structure of the abitibi belt superior province canada implications for mantle heat flow the results of new heat flow measurements are presented for eleven sites located in the abitibi greenstone belt of the archean superior province these new and previously published heat flow data are used with gravity and seismic data to constrain the crustal structure and composition of the abitibi subprovince and to determine the mantle heat flow beneath the canadian shield in order to analyze the long wavelength variations in heat flow and bouguer gravity anomaly the crust was divided into three layers with distinctive composition and physical properties average density heat production and thickness for each layer were varied within a range compatible with measurements and yielded crustal models consistent with gravity and heat flow data the dominant contribution to crustal heat production is that of a tonalitic type layer which has the lowest density the models require mantle heat flow to range between 10 and 14 mw m 2 the westward increase in heat flow requires the tonalitic layer to thicken from the grenville front toward the kapuskasing uplift at the expense of the greenstone supracrustals long wavelength gravity data are more affected by changes in crustal thickness than by composition and the low bouguer anomaly near the eastern grenville front is caused by 5 6 km of crustal thickening in greenstone terranes the long wavelength variations in heat flow are more useful for determining average crustal composition and the thickness of supracrustals than the gravity data

sediments deposited by the 2004 indian ocean tsunami along the malaysia thailand peninsula stratigraphy grain size distribution and foraminiferal assemblages of pre tsunami and tsunami sediment from the indian ocean tsunami at five sites along the malaysia thailand peninsula were analyzed to gain information on tsunami sediment source and deposition style between three and five stratigraphic units were identified at each site and contained between one and three fining upward sequences reflecting waning flow or pre backwash deposition coarser sand layers reflecting uprush high energy flow separated the fining upward sequences with the exception of one site sungai burong which contained a coarsening upward sequence all contacts between the pre tsunami and tsunami sediment were sharp or erosional medium and coarse sand dominated all of the tsunami sediment deposits and often contained shell fragments foraminiferal assemblages were able to differentiate pre tsunami sediment from tsunami sediment where no lithological or grain size distribution change was evident between two and four foraminiferal zones were identified at each of the five sites and provided estimates of sediment source and wave characteristics

complex lithospheric structure under the central baltic shield from surface wave tomography complex lithospheric structure under the central baltic shield from surface wave tomography

ostracodes reveal the sea bed origin of tsunami deposits 1 in rikuzentakata city ostracode assemblages in sediment deposited by the tohoku oki earthquake and tsunami of 11 march 2011 revealed that the sediment was derived from the seafloor from at least 9 m water depth and was transported inland more than 1 km the tsunami wave height at this location was higher than 10 m four hundred fifty seven modern ostracode assemblages were used in the modern analogue technique to estimate the depth source of the tsunami deposited assemblages the application of this method to paleo tsunami deposits may provide insight into past tsunami wave height and potentially earthquake slip and magnitude

shallow marine sediment cores record climate variability and earthquake activity off lisbon portugal for the last 2000 years abstract sea surface temperature sst river discharge and biological productivity have been reconstructed from a multi proxy study of a high temporal resolution sedimentary sequence recovered from the tagus deposition center off lisbon portugal for the last 2000 years sst shows 2 c variability on a century scale that allows the identification of the medieval warm period mwp and the little ice age lia high iron fe and fine sediment deposition accompanied by high n alkane concentrations and presence of freshwater diatoms during the lia 1300 1900 ad science 292 2001 662 suggest augmented river discharge whereas higher total alkenone concentrations point to increased river induced productivity during the mwp 550 1300 ad science 292 2001 662 larger mean grain size and low values of magnetic susceptibility and concentrations of fe n alkanes and n alcohols are interpreted to reflect decreased runoff at the same time increased benthic and planktonic foraminifera abundances and presence of upwelling related diatoms point to increased oceanic productivity on the basis of the excellent match found between the negative phases of the north atlantic oscillation nao index and the intensified tagus river discharge observed for the last century it is hypothesized that the increased influx of terrigenous material during the lia reflects a negative nao like state or the occurrence of frequent extreme nao minima during the milder few centuries of the mwp stronger coastal upwelling conditions are attributed to a persistent positive nao like state or the frequent occurrence of extreme nao maxima the peak in magnetic susceptibility centered at 90 cm composite core depth ccd is interpreted as the result of the well known 1755 ad lisbon earthquake the lisbon earthquake and accompanying tsunami are estimated to have caused the loss of 39 cm of sediment 355 years of record most of the lia and the instantaneous deposition of a 19 cm sediment bed

ostracods as tsunami tracers in holocene sequences this review analyses the ostracod record in holocene tsunami deposits using an overview of the 2004 indian ocean tsunami impact on its recent populations and the associated tsunamigenic deposits together with results from numerous investigations of other holocene sequences different features such as the variability of the local assemblages population density species diversity age population structure e g percentages of adults and juvenile stages or taphonomical signatures suggest that these microorganisms may be included amongst the most promising tracers of these high energy events in marshes lakes lagoons or shallow marine areas

rheological structure and dynamical response of the dss profile baltic in the se fennoscandian shield abstract numerical modelling was applied to study the present day state of stress and deformation under different tectonic loading conditions at the seismic baltic skj profile in south eastern finland and in estonia the finite element method was used to solve the numerical problem the two dimensional model was constructed using the results from both seismic and thermal studies along the profile the model is 700 km long and 200 km deep and is roughly divided into an inhomogeneous laterally layered crust and a homogeneous mantle lithosphere both the linear elastic and non linear elasto plastic rheologies were used elasto plasticity was achieved by calculating a rheological strength as a function of depth along the profile different tectonic load cases were analysed with displacement force and pressure type boundary conditions also the effect of different strain rates was investigated the results suggest that even with relatively low compressive stress levels the lower crust deforms in a plastic manner for a wet crustal rheology when applying a dry crustal rheology plastic yielding is attained only with much higher stress fields

temperature field modelling along the northern segment of the european geotraverse and the danish transition zone abstract a two dimensional numerical solution of the heat conduction equation was used to calculate the crustal temperature field along two profiles of the northern segment of the european geotraverse the fennolora profile baltic shield and profile 2 of the eugeno s project danish transition zone the solution of the 2 d steady state equation of heat conduction was solved with the integrated finite difference method the crustal structure was discretized by a rectangular grid seismic refraction results were used to calculate the corresponding distribution of heat generation we applied empirical equations linking seismic velocity with heat generation to convert the characteristic seismic velocity into heat production in the upper crust the temperature field shows no significant lateral variation the lower crust on the other hand is characterized by lateral and vertical variations of the temperature field mainly at tectonic transition zones i e precambrian to phanerozoic crustal domains in the baltic shield temperatures tend to decrease towards the north with increasing age of the shield as expected relatively low moho temperatures were obtained beneath the baltic shield 300 500 c whereas a maximum of 900 to 1000 c at the moho was found to correspond to high surface heat flow in southern sweden in the geologically complex danish transition zone the calculated moho temperatures reached values between 550 c in the shield region and 650 c under the danish basin the variation of mantle heat flow reflects the pattern of surface heat flow in the fennoscandian part of the shield the moho heat flow is 5 40 mw m2 in the danish part 25 30 mw m2 and below the danish basin up to 45 mw m2 with the present data set the model shows a remarkable coincidence between high q0 the temperature field and areas of major tectonic change sensitivity analysis shows that the surface heat flow and the heat generation in the upper crust are the most critical thermal parameters due to their relatively limited range of variation the heat production in the lower crust the thermal conductivity and corrections applied to the seismic velocities play only a secondary role on the two dimensional temperature field the differences between 1 d and 2 d temperature models are most pronounced in the lower crust where significant lateral temperature variations are seen

late holocene evolution of the southwestern donana national park guadalquivir estuary sw spain a multivariate approach four phases are distinguished in the late holocene evolution of the southwestern donana national park sw spain based on a multidisciplinary analysis of the sediments present in drill cores in the oldest phase 2400 2500 cal yr bp a coastal lagoon the roman lacus ligustinus was recognized in the central part of this area partly closed by the donana spit and limited by fluvial levees the following phase 2400 2200 cal yr bp is characterized by high energy events which caused the breakthrough of the donana spit and the creation of new littoral strands in the inner areas in the third phase 2200 2050 cal yr bp this new outlet was closed coinciding with the progradation of the donana spit the last phase 2050 cal yr bp recent comprises three periods a an unstable period 2050 1950 cal yr bp with the deposit of cheniers over the previous levees b an infilling period with a diminution of the marine influence and c the appearance of temporary ponds between the emerged levees and cheniers

geodynamics and rheology of the lithosphere along the dss profile sveka in the central fennoscandian shield abstract numerical modelling was carried out to investigate the rheological structure and properties of the northern part of the deep seismic sounding dss profile sveka this profile is located in central finland and it crosses the lake ladoga bothnian bay zone llbb which is the border between the proterozoic and the archaean domains data from seismic thermal electromagnetic and gravitational studies are used as initial parameters and also for analysing the results mainly dss data are used to construct the subsurface structures rheological and thermal models with different material properties are calculated first these results are then applied to the two dimensional finite element model of the sveka profile the rheologically defined model is furthermore subjected to compressive boundary conditions and the resulting response is suggested to give some understanding of the present day state of stress and deformational conditions in the lithosphere the rheology of the dss profile sveka seems to be fairly strong the proterozoic lower crust of the model is weaker than the archaean one finite element modelling shows that with moderate stress fields the crust remains still intact and only minor deformational areas are found these include brittle deformation in the uppermost proterozoic crust and plastic deformation in the lowermost crust lower crustal yielding present in few model cases is limited to very narrow zones at depths which are very close to the moho boundary changing the lower crustal composition from dry to wet reduces the strength in the lower crust remarkably which enables plastic deformation in the lowermost crust similar results are obtained with reduction of the strain rate value

sedimentary record of a tsunami during roman times bay of cadiz spain abstract historical data show that the gulf of cadiz has been exposed to destructive tsunamisduring at least the past 2000 yr the last tsunami was generated by the ad 1755 lisbon earthquake which affected the atlantic coasts of spain portugal and morocco today these littoral areas areintensely populated and the expected damage could be much greater tsunami studies are of greatimportance in helping to determine the recurrence interval of these events the presence of washover fan deposits on the inland margin of the valdelagrana spit bar cadiz spain indicates the occurrence of a high energy marine event ca 2300 cal yr bp historical geomorphological sedimentological palaeontological and geochronological data suggest that atsunami could have affected the area during roman times copyright 2002 john wiley sons ltd journal of quaternary science keywords tsunami deposits grain size palaeontology gulf of cadiz south spain introduction investigations of the geological records of past tsunamis arean important tool in helping to determine the recurrenceinterval of such events in a region these investigations arealso the only way of determining the prehistoric occurrenceand tsunami hazard in areas of infrequent seismic activity however at present it is dif cult to distinguish betweentsunami deposits and those laid down by other high energyevents such as a storm surge or hurricane recent work bygoff et al 2001 has helped to identify a series of diagnosticcriteria for tsunami deposits and research is underway tohighlight the differences between these and other high energyevents goff and chagu e goff in preparation j goff personalcommunication 2002 wave hydrodynamics the speci ccoastal setting morphology orientation availability and typeof sediments depositional environments tsunami magnitudeand tidal range are all factors that help to de ne the type andpreservation of tsunami deposits furthermore the ability todetermine the tsunamigenic source largely depends upon thepalaeoseismic and historical record e g goff et al 2001

diatoms as an aid in identifying late holocene tsunami deposits diatoms bacillariophyta help identify the onshore deposits of tsunamis from earthquakes on the cascadia subduction zone along the pacific coast of oregon washington and british columbia and on faults high in the north american plate in the puget sound area of washington at the copalis river washington diatom analyses suggest that a tsunami deposit about 300 calendric years old 300 yr bp originated from sandy shoals of the lower estuary rather than nearby beaches or coastal dunes at cultus bay and west point washington well preserved benthic estuarine diatoms in sand sheets overlying tidal marsh peat indicate that the deposits came from intertidal or nearshore areas of puget sound on an abruptly uplifted mudflat at the landward end of hood canal at lynch cove washington tidal flat diatoms refute the possibility of a terrestrial source for the sand diatoms in 300 yr bp tsunami deposits on the niawiakum river washington confirm that the sand in these deposits had a marine source and help

historical and pre historical tsunamis in the mediterranean and its connected seas geological signatures generation mechanisms and coastal impacts abstract the origin of tsunamis in the mediterranean region and its connected seas including the marmara sea the black sea and the sw iberian margin in the ne atlantic ocean is reviewed within the geological and seismotectonic settings of the region a variety of historical documentary sources combined with evidence from onshore and offshore geological signatures geomorphological imprints observations from selected coastal archeological sites as well as instrumental records eyewitnesses accounts and pictorial material clearly indicate that tsunami sources both seismic and non seismic e g volcanism landslides can be found in all the seas of the region with a variable tsunamigenic potential local regional and basin wide tsunamis have been documented an improved map of 22 main tsunamigenic zones and their relative potential for tsunami generation is presented from west to east the most important tsunamigenic zones are situated offshore sw iberia in the north algerian margin in the tyrrhenian calabria and messina straits in the western and eastern segments of the hellenic arc in the corinth gulf of central greece in the levantine sea offshore the dead sea transform fault and in the eastern side of the marmara sea important historical examples including destructive tsunamis associated with large earthquakes are presented the mean recurrence of strong tsunamis in the several basins varies greatly but the highest event frequency 1 96 years is observed in the east mediterranean basin for most of the historical events it is still unclear which was the causative seismic source and if the tsunami was caused by co seismic slip by earthquake triggered submarine landslides or by a combination of both mechanisms in pre historical times submarine volcanic eruptions i e caldera collapse massive pyroclastic flows volcanogenic landslides and large submarine landslides caused important tsunamis although little is known about their source mechanisms we conclude that further investigation of the tsunami generation mechanisms is of primary importance in the mediterranean region inputs from tsunami numerical modeling as well as from empirical discrimination criteria for characterizing tsunami sources have been proved particularly effective for recent well documented aseismic landslide tsunamis e g 1963 corinth gulf 1979 cote d azur 1999 izmit bay 2002 stromboli volcano since the tsunami generation mechanisms are controlled by a variety of factors and given that the knowledge of past tsunami activity is the cornerstone for undertaking tsunami risk mitigation action future interdisciplinary research efforts on past tsunamis are needed

expanding the proxy toolkit to help identify past events lessons from the 2004 indian ocean tsunami and the 2009 south pacific tsunami article i nfo some of the proxies used to identify palaeotsunamis are reviewed in light of new findings following the 2004 indian ocean tsunami and the 2009 south pacific tsunami and a revised toolkit provided the new application of anisotropy of magnetic susceptibility ams to the study of tsunami deposits and its usefulness to determine the hydrodynamic conditions during the emplacement of tsunami sequences together with data from grain size analysis are presented the value of chemical proxies as indicators of saltwater inundation associated marine shell and or coral high energy depositional environment and possible contamination is demonstrated and issues of preservation addressed we also provide new findings from detailed studies of heavy minerals new information gathered during the unesco international oceanographic commission ioc international tsunami survey of fine onshore sediments following the 2009 south pacific tsunami is presented and includes grain size chemical diatom and foraminifera data the tsunami deposit varied ranging from fining upward sand layers to thin sand layers overlain by a thick layer of organic debris and or a mud cap grain size characteristics chemical data and microfossil assemblages provide evidence for marine inundation from near shore and changes in flow dynamics during the tsunami

s and p velocity heterogeneities within the upper mantle below the baltic shield abstract upper mantle structure beneath the baltic fennoscandian shield is investigated using non linear tomographic inversion of relative arrival time residuals 52 selected teleseismic earthquakes recorded by 45 broadband stations of the swedish national seismological network snsn provide 1532 good quality s wave relative arrival times sv and sh arrival time residuals were initially analyzed independently providing two separate models these reveal several consistent major features many of which are also consistent with p wave results lateral velocity variations of 3 4 are observed to depths of at least 470 km the correlation between the sh and sv models is investigated and shows a pattern of minor but significant differences down to around 150 200 km depth below which the models are essentially similar direct cell by cell comparison of the model velocities reveals a similar pattern with velocity differences between the models of up to 4 numerical tests show that differences in the two s wave models can only be partially attributed to noise and limited resolution and some features are attributed to the effect of large scale anisotropy one of the significant and sharp discrepancies between the s models coincides with a presumed boundary between archean and proterozic domains suggesting different anisotropic characteristics in the two regions

isotopic and geochemical constraints on the evolution of the 1 93 1 79 ga svecofennian crust and mantle in finland the central part of the svecofennian domain in finland is characterized by thick lithosphere with crustal thickness up to 60 65 km major collisional events at 1 91 1 90 ga and 1 89 ga and a thrusting event at 1 86 1 84 ga the latter due either to continuation of shortening or to a separate intracrustal collision are considered the major causes of crustal thickening the origin of the svecofennian domain has been formerly attributed to mixing of depleted mantle melts with variable amounts of archaean crustal component via subduction but the new data and reinterpretation of older data imply that besides juvenile crust the svecofennian domain also contains older palaeoproterozoic crustal components no archaean component is found in the 1 93 1 91 ga gneissic tonalites and related felsic volcanics end t 1 4 which occur in the savo belt sb adjacent to the archaean craton the depleted mantle model ages vary from 1 94 ga to 2 33 ga with most values 2 0 ga the analysed syntectonic post thickening granitoids 1 89 ga in the sb exhibit positive end t values ranging from 2 8 to 3 0 pointing to a juvenile source the hypersthene granitoids are similar in age but show epsilon values around 1 which are only slightly lower than found in em derived mafic rocks the isotopic and geochemical data for the central finland granitoid complex and tampere schist belt indicate the occurrence of evolved thick crust 2 0 ga and associated lithospheric mantle already at 1 91 ga the southernmost part of the southern svecofennian in finland also shows evolved type crust 2 0 ga a tentative model for the development of crust and mantle is presented it includes the occurrence of continental nucleus surrounded by more juvenile island arc accretions two successive collisional events thickened both the crust and the subcontinental lithospheric mantle with the greatest relative amount of thickening occurring in the mobile zones convective removal of the lowermost parts of thickened lithosphere caused an upwelling of hot asthenosphere increase in the geotherm and melting of both the enriched subcontinental lithospheric mantle and the convective depleted asthenosphere mafic magmatism during the post thickening stage 1 89 ga thus varied from dominantly enriched to dominantly depleted mantle melts and was associated with variable crustal contamination the thickening of the lithosphere in the central part of the svecofennian domain was not followed by large extension suggesting that the thickness was already great 1 88 1 80 ga ago this together with the thick high velocity lower crust could have provided the isostatic balance needed to stabilize the thick crust

anomalously low heat flow density in eastern karelia baltic shield a possible palaeoclimatic signature abstract we report new heat flow density hfd values in seven drill holes in the kamennye lakes area in eastern karelia russia approximately at latitude 63 15 n longitude 36 10 e the investigated holes are 250 750 m deep and they intersect archaean ultrabasic serpentinites and talc carbonate rocks measured gradients range from 0 8 to 3 7 mk m 1 and the apparent hfd values from 2 4 to 11 6 mw m 2 the holes are not technically disturbed by fluid flow or any drilling effects average heat production of the rocks as analysed in the core samples of the deepest measured hole is 0 25 w m 3 but the low heat production is not a critical factor in producing the low hfd values this is due to refraction of heat as shown with 2 d conductive simulations of heat transfer in a low heat production formation surrounded by higher heat production hydrogeological disturbances can be ruled out by the presence of saline groundwater in the sections deeper than 150 400 m and low topographic variation in the area as well as peclet number estimates which suggest negligible convective heat transfer in the bedrock all the temperature profiles are curved indicating recent palaeoclimatic disturbances inversion studies with singular value decomposition techniques yielded a climatic warming of about 1 0 1 5 k which started 150 200 years ago and was preceded by a cool period which lasted about 100 years nevertheless recent climatic changes cannot explain the very low apparent hfd values but long period effects of the weichselian glaciation are sufficient to decrease the hfd values to the levels measured these effects were investigated with forward simulations and suggest that present temperature gradients in the range of 1 4 mk m 1 in the uppermost 1 km can be created by a very cold ground temperature 10 to 15 c during the glaciation time 60 11 ka ago

terrestrial heat flow and groundwater circulation in the bedrock in the central baltic shield abstract unpublished heat flow measurements from 17 drillholes in finland central baltic shield are presented the holes range from 270 to 1080 m in depth sharp vertical changes in the heat flow density and in the temperature gradient indicating groundwater flow disturbances were detected in eight holes the variations in heat flow were typically of the order of 5 10 mw m 2 in many cases the groundwater flow concept was supported by geological logs and other borehole measurements which indicated the existence of fracture zones at the same depths as the flow the flow zones were usually encountered at depths of less than 500 m but flows between fracture zones in the holes were detected even deeper at as much as 930 m according to recent groundwater studies in the same holes the water flowing in the fracture zones seems to be fresh or only slightly saline in composition this can be taken as an indication of relatively rapidly circulating groundwater in contrast to the more saline and more stagnant groundwater encountered deeper in the holes the results indicate that disturbances in heat flow induced by groundwater flow may be much more common in areas of crystalline bedrock than has previously been realized the apparent heat flow densities mean 35 0 3 0 mw m 2 agree well with values published previously from the central baltic shield but the results from southern and western finland indicate regionally above average heat flow values 45 mw m 2

distinguishing tsunami and storm deposits an example from martinhal sw portugal abstract geological identification of past tsunamis is important for risk assessment studies especially in areas where the historical record is limited or absent the main problem when using the geological evidence is to distinguish between tsunami and storm deposits both are high energy events that may leave marine traces in coastal stratigraphic sequences at martinhal sw portugal both storm surge and tsunami deposits are present at the same site within a single stratigraphic sequence which makes it suitable to study the differences between them excluding variations caused by local factors the tsunami associated with the lisbon earthquake of november 1st 1755 ad had a major impact on the geomorphology and sedimentology of martinhal it breached the barrier and laid down an extensive sheet of sand as described in eyewitness reports besides the tsunami deposit the stratigraphy of martinhal also displays evidence for storm surges that have breached and overtopped the barrier flooding the lowland and leaving sand layers both marine derived flood deposits show similar grain size characteristics and distinctive marine foraminifera the most important differences are the rip up clasts and boulders exclusively found in the tsunami deposit and the landward extent of the tsunami deposit that everywhere exceeds that of the storm deposits identification of both depositional units was only possible using a collection of different data and extensive stratigraphical information from cores as well as trenches

deep geothermal structure and mantle heat flow along the barents sea east alps geotraverse the deep geothermal structure of the continental crust along the barents sea eastern alps profile is investigated numerical geothermal models are constructed the mantle heat flows and the moho temperatures are computed for different tectonic blocks of the crust within ancient platform areas the mantle heat flow varies from 15 28 mw m 2 in the baltic shield to 6 14 mw m 2 in the stable russian plate in the baltic syncline the mantle heat flow is about 25 33 mw m 2 the maximum mantle heat flow value of 40 m w m 2 characterizes the central european platform mantle heat flow values vary from 15 to 35 mw m 2 in the hercynian part of central europe for the thermal model the seismic velocity data are used the moho temperature values vary from 400 c in the ancient platform area to 900 1000 c in the alpine zone in the northern baltic shield tm 600 c

heat flow and lithospheric thermal regime in the northeast german basin abstract new values of surface heat flow are reported for 13 deep borehole locations in the northeast german basin negb ranging from 68 to 91 mw m 2 with a mean of 77 3 mw m 2 the values are derived from continuous temperature logs measured thermal conductivity and log derived radiogenic heat production the heat flow values are supposed free of effects from surface palaeoclimatic temperature variations from regional as well as local fluid flow and from thermal refraction in the vicinity of salt structures and thus represent unperturbed crustal heat flow two d numerical lithospheric thermal models are developed for a 500 km section along the dekorp basin 9601 deep seismic line across the basin with a north eastward extension across the tornquist zone a detailed conceptual model of crustal structure and composition thermal conductivity and heat production distribution is developed different boundary conditions for the thickness of thermal lithosphere were used to fit surface heat flow the best fit is achieved with a thickness of thermal lithosphere of about 75 km beneath the negb this estimate is corroborated by seismological studies and somewhat less than typical for stabilized phanerozoic lithosphere modelled moho temperatures in the basin are about 800 c heat flow from the mantle is about 35 to 40 mw m 2 in the southernmost part of the section beneath the harz mountains higher moho temperatures up to 900 to 1000 c are shown while the relatively high level of surface heat flow in the negb obviously is of longer wave length and related to lithosphere thickness changes in crustal structure and composition are responsible for short wave length anomalies

coeval versus reciprocal mixed carbonate siliciclastic deposition middle devonian baltic basin eastern europe implications from the regional tectonic development the middle devonian narva succession in the baltic basin represents a significant turnaround in the history of the basin the detailed study of core and outcrop sections and the three dimensional correlations across the baltic basin reveal a carbonate dominated mixed retrogressive succession overlain by a siliciclastic dominated progradational succession the palaeogeographic reconstructions show how the shallow tide influenced basin expanded from south west to north east and later during the transgression also to the north south and east the transgressive portion of the basin fill is dominated by carbonate rich sabkha and supratidal to intertidal deposits on the basin margins and subtidal carbonates in the basin centre siliciclastic material was derived by tidal currents and storm waves from the south west through a tidal inlet and flood tidal delta complex this initial transgressive phase is characterized by the lack of subsidence or even episodic uplifts in the northern north western part of the basin margin shown by convergence of timelines and the thin 30 m transgressive succession in contrast on the southern margin the facies associations stack vertically into a 70 to 80 m thick succession indicating significantly higher subsidence rates the upper part of the transgressive phase indicates subsidence across the whole basin the upper progradational portion of the basin fill is dominated by coarse siliciclastic tide influenced deltaic deposits that rapidly prograded from north west to south east this detailed study on the narva succession shows that siliciclastic and carbonate deposition was coeval and that mixing occurred at different temporal and spatial scales the mixing was controlled by grain size volume and location of siliciclastic input rather than relative sea level changes as suggested in widely used reciprocal mixing models it is suggested that the forebulge of the scandinavian caledonian fold and thrust belt migrated to the north western margin of the baltic basin during the earliest eifelian as indicated by the lack of subsidence and probable uplift in the northern north western margin during the early transgressive phase the forebulge migration ceased although the forebulge had already started to subside during the later stages of the transgressive phase the deltaic progradation is interpreted to be associated with the orogenic collapse and uplift in the scandinavian caledonides that caused the erosion of the foreland basin fill and the coarse sediment transport into the baltic basin

geophysical interpretation of the crustal and upper mantle structure in the wiborg rapakivi granite area southeastern finland abstract the rapakivis in southeastern finland and russian karelia cover a total area of more than 20 000 km 2 and comprise the proterozoic 1 6 1 3 ga anorogenic wiborg ahvenisto suomenniemi and onas batholiths and associated mafic rocks a model of the crustal and upper mantle structure in this area based on gravity aeromagnetic deep seismic sounding and petrophysical data is presented the average density 2625 kg m 3 of the batholiths is lower than that of the surrounding svecofennian rocks by about 80 kg m 3 the density histogram of the rapakivi granites is divided into two normally distributed components with mean densities of 2625 kg m 3 major and 2690 kg m 3 minor respectively there are related local gravity anomalies the susceptibility histogram of the rapakivi granites is decomposed into five log normally distributed components the two major components have mean susceptibilities of 165 and 1305 10 6 si units the former component 40 is virtually paramagnetic and the latter 60 is weakly ferromagnetic the two components with mean susceptibilities of 6000 and 13 5000 10 6 si units constitute only 3 of all the samples associated gabbro anorthosites also have high susceptibilities 1450 30 370 10 6 si units these ferrimagnetic rocks cause noticeable local aeromagnetic anomalies an extensive bouguer anomaly low is associated with the batholiths a pronounced regional high surrounds this low the range of values is nearly 60 mgal the anomaly pattern is primarily the result of superposition of the gravity low which is due to the relatively low density upper and middle crust onto the broader gravity high that is due to the uplifted moho according to the published deep seismic sounding results the crust is 41 km thick in the rapakivi region thus it is 6 20 km thinner than to the west north and south of the rapakivi batholiths the refraction model also implies a 6 km thick high velocity body at a depth of 10 km this body has a high v p v s ratio and is interpreted as gabbro anorthosite the magnetic anomaly values in the rapakivi area are slightly higher than those in the surrounding schist areas but lower than the values in the metavolcanic belt to the west within the wiborg batholith there is a zone of positive regional magnetic anomalies with a separate well defined magnetic high of about 400 nt in the western part this anomaly is interpreted as a pipe like magnetic body with an abnormally strong magnetization the upper surface of the body lies at depths between 12 and 15 km the body extends from the upper to the lower crust the model derived from geophysical data supports a proterozoic mantle upwelling which provided excess heat to cause uplift and partial melting of both the upper mantle and the lower crust partial melting of the upper mantle produced intrusions of gabbro anorthosites and diabases while extensive partial melting of the lower crust produced rapakivi magmas and caused their emplacement into the upper crust

is there a relationship between seismic velocity and heat production for crustal rocks abstract several investigators proposed an empirical relationship between heat production and seismic velocity for rocks typical of the continental crust these relationships could allow for indirect resolution of the distribution of heat producing elements with depth new heat production data for rock samples from the pikwitonei granulite domain and the sachigo granite greenstone subprovince of the superior province do not follow these relationships indicating that heat production cannot be reliably predicted from seismic velocity these two parameters are not likely to be related as velocity depends upon the major mineral constituents of rocks whereas heat production results from radiogenic components concentrated in both major and trace minerals in rocks

ostracoda crustacea as indicators of subaqueous mass movements an example from the large brackish lake tangra yumco on the southern tibetan plateau china abstract a conceptual model of subaquaeous mass movements and ostracod distribution in lacustrine sediment event layers was tested integrated methods geophysical sedimentological and microfossil analyses were performed on a short sediment core retrieved from 220 m water depth in the large brackish lake tangra yumco on the southern tibetan plateau central asia the event layers of the core and their underlying and overlying sediments were investigated four major event layers composed of sandy silt with graded bedding are interpreted as turbidites the fifth layer consisting of fine sand and silt and without graded bedding is characterized as a debrite the ostracods small bivalved aquatic crustaceans identified are leucocytherella sinensis huang 1982 leucocythere dorsotuberosa huang 1982 limnocythere inopinata baird 1843 and fabaeformiscandona gyirongensis huang 1982 ostracod evidence is a good proxy for the evaluation of massive sediment event layers formed by subaqueous mass movements four assumptions of a conceptual model were confirmed i fine grained sediments of event layers turbidite deposits contain very low numbers of ostracods compared to the underlying and overlying sediments ii ostracods are sorted according to size and display high abundance and high proportion of adult valves of leucocytherella sinensis at the base of event layers iii a relatively low number of carapaces is present within the event layers and iv the recolonization of newly event generated habitats by pioneer assemblages transforming into pre event association gradually

lithospheric thermal structure in the baltic shield summary steady state heat conduction modelling was carried out to calculate the crustal temperature field and thermal lithosphere thickness in the baltic shield the radiogenic sources at the surface were fixed depending on the age of the crust below the uppermost 10 kilometres a relationship between heat generation and p wave velocity was applied and seismic structure was used to define individual crustal blocks of specific thermal parameters small scale surface heat flow density anomalies are interpreted as lateral variations of heat generation within the upper part of the crust whereas the large anomaly in the southern part of the shield is attributed to an anomalously high mantle heat flow density the results are shown on maps outlining mantle heat flow density moho temperature and thermal lithosphere thickness a relationship between subcrustal temperature and moho depth was found except for southern sweden the lithospheric thickness is found to exceed 200 km in the bothnian gulf northern central finland and part of the kola peninsula where temperatures at the moho are less than 500 c the temperature gradient at the top of the mantle has on the average a value of 7 5 mk m and the mantle heat flow density varies from 19 to 25mwm 2 towards the south the lithospheric thickness decreases until it attains a value lower than 100km under southern sweden in this latter area the moho temperature and mantle heat flow density are remarkably high 700 900 c and 30 45 mw m 2 respectively as well as the temperature gradient which amounts to 10 mk m

stratigraphic and microfossil evidence for late holocene tsunamis at swantown marsh whidbey island washington abstract four muddy sand sheets occur within a tidal marsh peat at swantown on the west coast of whidbey island washington the two largest sand sheets pinch out about 100 m inland and became thinner and finer grained landward all four sand sheets contain marine microfossils and have internal stratification they record repeated inundation of the marsh over a short time period by distinct pulses of sediment laden ocean water consistent with deposition by a tsunami wave train the layers have been radiocarbon dated to 1160 1350 1400 1700 1810 2060 and 1830 2120 cal yr b p the overlap in age between the two youngest layers and inferred great earthquake events at the cascadia plate boundary some 250 km to the west suggests they were emplaced by tsunamis from this source area the two older layers do not correlate with plate boundary events they may be products of tsunamis caused by earthquakes on local faults in the strait of juan de fuca or by submarine landslides in this area

hydrological disturbances of the conductive heat flow in stable continental crust abstract geophysical data generally support the presence of free aqueous fluids in the crust to at least the depth of the 700 750 c isotherm where granulite facies conditions are reached which are presumed to have no free water the fluid phase distribution and transport of fluid in rocks strongly depend on the rheological conditions in the lithologically heterogeneous crust changes in rheological regime can produce quite complex sandwich like fluid transport layering including domains of upward migration very impermeable layers or thin reservoirs with nearly horizontal fluid transport in the present study two two dimensional thermal models of the stable continental crust with different spatial configurations of fluid systems have been calculated the results show that such systems redistribute heat in the crust and give rise to zones of concentrated heat energy storage and transfer the pattern of the disturbances to the conductive heat flow depends on the arrangement of the fluid systems which is a function of the crustal structure temperature and regional stress field and shows significant lateral and vertical variations even at very low velocities of the fluid percolation a few millimetres per year the disturbances to the conductive heat flow may reach 30 60

megatsunami deposits on kohala volcano hawaii from flank collapse of mauna loa the origin of coastal and high elevation marine gravels on the hawaiian islands of lanai and molokai is controversial because the vertical tectonics of these islands is poorly constrained the gravels are either from eustatic highstands or were left by massive tsunamis from offshore giant landslides in contrast at kohala on the island of hawaii where continuous subsidence is well established lithofacies analysis and dating of a fossiliferous marine conglomerate 1 5 61 m above present sea level support a tsunami origin and indicate a runup of 400 m 6 km inland the conglomerate age 110 10 ka suggests a tsunami caused by the ca 120 ka giant alika 2 landslide from nearby mauna loa volcano

relationship between seismic velocity and heat production comparison of two sets of data and test of validity abstract an empirical relationship between compressional wave velocity v p and radiogenic heat generation a is frequently used to estimate heat production distributions in the continental crust two data sets from rybach and buntebarth 1 and kern and siegesmund 2 have been re evaluated and made comparable bulk density was included as a further parameter to investigate the relationships v p a v p and a statistical analysis shows reasonably high and comparable regression coefficients for the first two relationships but much less agreement for the a relationship

geothermal modelling of the lithosphere in the central baltic shield and its southern slope lithospheric temperature and heat flow density hfd were studied in the central baltic fennoscandian shield and its subsurface continuation to the south along a transect trending from eastern finland to southern estonia the transect represents an example of a low hfd 30 mw m 2 archaean craton on a thick 150 190 km lithosphere surrounded by early and middle proterozoic mobile belts on a thinner 110 150 km lithosphere with slightly elevated hfd 35 55 mw m 2 numerical 2 d conductive models were constructed in which peridotite solidus temperatures were assigned to those depths which correspond to the seismically determined lithosphere asthenosphere boundary this technique was found to reduce the effect of uncertainties in heat production and thermal conductivity values on the simulation results upper crustal heat production values for the finnish terrain were taken from published geochemical analyses of outcropping rocks for the estonian terrain new heat production values were measured from core samples representing nineteen deep boreholes middle and lower crustal lithologies were estimated with the aid of the deep seismic vpvs data and corresponding heat production values were adapted from global xenolith averages and from data for granulites cropping out in other precambrian areas the results of the modelling suggest that the lithosphere and moho depth variations are only weakly reflected in the measured surface heat flow data which are mainly controlled by heat sources in the upper crust the simulated heat flow densities at 50 km depth approximately at the moho are relatively low and range from 12 mw m 2 at the archaean northeastern end to 19 mw m 2 on the proterozoic southwestern end of the transect simulated temperatures at 50 km depth increase from northeast to southwest ranging from 450 550 c in eastern finland to about 650 c in estonia sensitivity of the simulations to parameter changes was studied by varying the heat production and thermal conductivity values the extreme values for the moho temperature estimates thus obtained may be about 50 k lower or 100 k higher than the values above the corresponding sensitivity of the moho hfd is about 6 mw m 2 and of the surface hfd 5 20 mw m 2 respectively

crust and upper mantle structure along the dss baltic profile in se finland summary the 430 km long dss baltic profile in se finland runs through the rapakivi intrusion the svecokarelian geosynclinal complex including the ladoga bothnian bay zone and the archean basement complex a brief description of field operations in 1982 is presented record sections of p and s waves were used for the interpretations a starting model was constructed by inverse methods and improved by dynamic ray tracing modelling three blocks are indentified on the cross section from sw to ne these are the southern associated with the rapakivi massif depth to moho m about 40 km the central ladoga bothnian bay zone with m of approximately 55 60 km and the northern archean crystalline basement with m about 40 45 km the average crustal velocity is 6 6 6 7 kms the crustal structure along the baltic profile is compared with the surrounding dss profiles finnish sveka and soviet kern tulos and ladoga profiles the eastern border of the ladoga bothnian bay zone was located and specific features of the crust and uppermost mantle along the profile area are discussed

high energy marine flood deposits on astypalaea island greece possible evidence for the ad 1956 southern aegean tsunami high energy marine sediments are described from livadia and stavros astypalaea island greece which are tentatively interpreted to be associated with the southern aegean tsunami of 9th july ad 1956 at livadia the marine provenance of imbricated pebble deposits referred to here as the imbricated clast unit or icu are inferred from two observations firstly the similarity between the clasts comprising the icu and contemporary beach sediments and secondly the inclusion of foraminiferal tests within the sediment matrix derivation from the ad 1956 tsunami rather than from a storm surge is inferred from the uniqueness of the deposits within the sedimentary record their distinct imbrication and 137cs and 210pb dating of overlying and underlying sediments the top of the icu occurs at 2 00 metres above sea level m a s l indicating a minimum flood level at this location at stavros a gravel with rounded clasts incorporating marine mollusca is found on exposed cliff surfaces up to an elevation of 10 00 m a s l these gravels are also interpreted as having been deposited by the ad 1956 tsunami the elevation of the deposits and topographic observations indicate that previously reported run up elevations were over estimated the results shown here represent the first systematic investigation into sedimentary deposits possibly associated with a modern tsunami within the aegean sea region of greece

a high energy deposit in the byzantine harbour of yenikapi istanbul turkey abstract a byzantine harbour theodosian harbour has been uncovered during excavations at yenikapi with a stratigraphic sequence spanning the past 7000 bp in the marine part of the sedimentary sequence a high energy deposit has been interpreted as being of tsunami origin and related to the earthquake of 557 ad this paper presents a bio sedimentological analysis of this facies the unit is characterised by coarse sands and gravels containing reworked material such as woods bones marble blocks amphora fragments ceramics coins shells and plant remains the thickness of the facies varies between 10 and 100 cm the sediment matrix is poorly sorted with skewness values indicative of a sub tidal fine sand environment many of the marine taxa have been reworked and diverse ecological assemblages are represented lagoonal coastal and open marine species this unit is divided into three facies consistent with different phases of the tsunami drowning and water retreat the basal facies corresponds to two tsunami wave trains and the upper facies indicates the backwash flow

sedimentary and microfossil imprint from historical earthquakes and tsunamis jalisco coast mexican subduction abstract tsunamis are high energy events capable of leaving their imprint in the geological record the western mexican pacific coast located in the mexican subduction zone is prone to large earthquakes m 8 0 where tsunami hazard has been underrated the geologic archive obtained in a sheltered coastal lagoon was analyzed applying a multi proxy approach to reveal the occurrence of historical earthquakes in the jalisco coast foraminifera and ostracoda aid identifying earthquake and tsunami geologic evidence in this section of the mexican pacific coast where tropical conditions prevail we present the evidence of changes in stratigraphy grain size biostratigraphy supported by archaeomagnetic dating they were complemented with published 210pb dating magnetic properties and historical data we identified three events the tsunami deposit left by the june 3rd 1932 tsunami produced by the largest earthquake m 8 2 recorded in instrumental history in mexico and the coseismic deformation resulting from the 1932 event also a probable tsunami deposit likely produced by an historical earthquake in 1900 and the coseismic deformation associated to this event and the coseismic deformation resulting produced by the 1563 earthquake the site geomorphology with a marginal lagoon closed by a little barrier 7 m 1 m above sea level precludes tropical storms as responsible for marine incursions this work contributes to strengthening the earthquake and associated tsunamis chronology aiming to improve coastal hazard assessment for the area

deep temperatures and lithospheric thickness along the european geotraverse abstract one dimensional steady state heat conduction models in the crust and upper mantle for 24 areas along the european geotraverse egt show that temperatures are higher beneath young geological regions at the moho they range from 450 to 825 c heat flowing out from the mantle varies from 18 to 72 mw m2 and the contribution of crustal heat flow density evaluated by the correlation between seismic velocity and the abundance of radioactive elements accounts for about 48 of the surface heat flow density the temperature gradient below moho from about 5 to 23 mk m is low where the surface heat flow density reaches its minimum values the depth at which the geotherms reach 0 85 of the mantle melting temperature is greater in the precambrian and caledonian areas with a maximum value of about 195 km under the early proterozoic scandinavian shield in the hercynian and alpine areas this depth is generally lower higher values maximum 150 km coincide with the orogenic belts and the continental block of sardinia and corsica under the ligurian sea and the sardinian channel the lithospheric thickness decreases remarkably to about 50 km globally the lithosphere thickness is controlled by the mantle heat flow density which decreases according to a power law with an increase in the lithosphere asthenosphere depth

the precambrian continental crust its structure composition and evolution as revealed by deep drilling in the u s s r abstract petrologic geochemical studies of the kola superdeep and other deep borehole sections drilled in the precambrian basement of the east european platform are discussed proterozoic metasediments and metavolcanic rocks that constitute the pechenga palaeorift and the underlying archaean granite gneiss basement were detected by the kola borehole in the 0 6842 m and 6842 12064 m intervals respectively zones of density decrease by hydrofracture resulting from progressive metamorphism under closed system conditions were identified in the upper crust at a 4500 9000 m depth sharp textural variations of rocks an increase in porosity and the presence of mineralizing fluids are specific features of these zones which may have contributed to tectonic deformation and metamorphically produced ore formation deep boreholes drilled into the more eroded archaean basement of the tatar dome provided information that was used for constructing a petrologic geochemical model of the lower crust to a depth of 25 30 km adacitic trondhjemitic composition for the primeval continental crust was calculated by extrapolation of geochemical trends established for the lower crust we propose that the lower crust formed as a result of an initial melting of the earth s chondrite shell and only existed in pre archaean times we also present data on temperatures and distribution of radiogenic elements in the kola and some other borehole sections a heat production model is proposed for the archean crust according to the model the crustal contribution to the heat flow is 25 mw m 2 or 52 of the total heat flow and that of the mantle is 22 24 mw m 2 or 48 of the total flow

layered mantle at the karelian craton margin p t of mantle xenocrysts and xenoliths from the kaavi kuopio kimberlites finland peridotitic clinopyroxene cpx and pyrope garnet xenocrysts from four kimberlite pipes in the kaavi kuopio area of eastern finland have been studied using major and trace element geochemistry to obtain information on the vertical compositional variability of the underlying mantle the xenocryst data when combined with the petrological constraints provided by peridotite xenoliths yield a relatively complete section through the lithospheric mantle single grain cpx thermobarometry fits with a 36 mw m2 geotherm calculated using heat flow constraints and xenolith modes and geophysical properties ni thermometry on pyrope xenocrysts gives 700 1350 c and based on the cpx xenocryst xenolith geotherm indicates a wide sampling interval ca 80 230 km plotting pyrope major and trace element compositions as a function of temperature shows there are three distinct layers in the local lithospheric mantle 1 a low temperature 850 c harzburgite layer distinguished by ca rich but ti y and zr depleted pyropes the xenoliths originating from this layer are all fine grained garnet spinel harzburgites with secondary cpx 2 a variably depleted lherzolitic harzburgitic and wehrlitic horizon from 950 to 1150 c or 130 to 180 km 3 a deep layer from 180 to 240 km composed largely of fertile material the peridotitic diamond window at kaavi kuopio stretches from the top of the diamond stability field at 140 km to the base of the harzburgite bearing mantle at about 180 km implying a roughly 40 km wide prospective zone

sedimentological and geoarchaeological evidence of multiple tsunamigenic imprint on the bay of palairos pogonia akarnania nw greece abstract this paper presents evidence of multiple tsunami impact on the bay of palairos pogonia nw greece during the holocene based on detailed geo scientific studies altogether 41 vibracores were drilled to detect high energy influence in the stratigraphical record layers of coarse grained allochthonous marine deposits were found intersecting autochthonous fine grained back beach sediments in the palairos coastal plain on top of beach or marly bedrock units at pogonia beach and along the pogonia cliff section high energy deposits are associated with specific sedimentary structures such as fining upward sequences rip up clasts basal erosional contact bi to multimodal grain size distribution lamination and co existence of both well rounded and angular sharply edged components all of them typical of tsunami impact macro and microfaunal analyses revealed tsunami related input of numerous ex situ marine species and mostly angular shell debris into quiescent fresh to brackish water environments by high energy and long distance transport geophysical methods helped to find subsurface structures and to seize the lateral extent of tsunami layers ca fe ratios derived from xrf measurements were used to trace tsunami influence inland most important is the widespread spatial distribution of the tsunamites with a lateral extent between 70 m at the pogonia cliff section 200 m at pogonia beach and 1 km in the central palairos plain and overall tendencies of fining and thinning towards inland highest elevations of tsunamites were found around pogonia village at ca 7 5 m a s l vibracore data give evidence that the overall coastal evolution has been strongly affected locally even controlled by multiple high energy impact a conspicuous geoarchaeological tsunamite up to 1 5 m thick was found at pogonia cliff consisting of mixed marine sand pebbles bio erosively altered stones shell debris foraminifers and terrigenous material abundant ceramic fragments bones building material it is directly associated with the submerged remains of an ancient mole which was destroyed and its building material partly dislocated by the same event dating of tsunamites was accomplished by archaeological age determination of diagnostic sherds and by radiocarbon and luminescence dating techniques strong tsunami events were dated to the beginning of the 6th the mid 5th the 4th 3rd and the late 2nd millennia bc as well as to the 4th 3rd century bc on a regional scale the recurrence interval for large events is ca 500 1000 years at least twice during the late holocene the palairos coastal plain was flooded quasi contemporaneously from both the northern and southern side

radiogenic heat production in the continental crust abstract the thermal structure and evolution of continents depend strongly on the amount and distribution of radioactive heat sources in the crust determining the contribution of crustal rocks beneath a superficial layer is a major challenge because heat production depends weakly on major element composition and physical properties such as seismic wavespeed and density enriched granitic intrusives that lie at the current erosion level have a large impact on the surface heat flux but little influence on temperatures in the deep crust many lower crustal rocks that are poor in heat producing elements are restites from ancient orogenic events implying that enrichment of the upper crust was achieved at the expense of deeper crustal levels for the same total heat production concentrating heat sources in an upper layer acts to reduce temperatures in the lower crust thereby allowing stabilization of the crust the present day structure of the crust is a consequence of orogeny and should not be adopted for thermal models of the orogenic event itself this review summarizes information extracted from large data sets on heat flow and heat production and provides estimates of crustal stratification and heat production in several geological provinces analysis of global and regional data sets reveals the absence of a positive correlation between surface heat flow and crustal thickness showing that the average crustal heat production is not constant differences of heat flow between geological provinces are due in large part to changes of crustal structure and bulk composition collating values of the bulk crustal heat production in a few age intervals reveals a clear trend of decrease with increasing age this trend can be accounted for by radioactive decay indicating that thermal conditions at the time of crustal stabilization have not changed significantly for the average crustal thickness of 40 km moho temperatures are near solidus values at the time of stabilization suggesting an intrinsic thermal control on crustal thickness and heat production distribution crustal thickening by more than about 10 km above this mean value induces changes of gravitational potential energy that exceed the strength of the lithosphere for several provinces where strong constraints on heat production are available it is shown that prior to intracrustal fractionation only modest amounts of thickening were needed to generate the conditions of ultra high temperature metamorphism the tell tale signature of crustal heat production is anatectic and metamorphic events that lag the cessation of orogenic activity by several tens of million years crustal heat production is decreasing with time because it is due to the radioactive decay of uranium thorium and potassium its rundown is responsible for the secular cooling of lithospheric roots at a typical rate of about 100 k gy 1 implying complex thermal interactions with a convecting mantle that is not cooling at the same rate

sedimentology of the december 26 2004 sumatra tsunami deposits in eastern india tamil nadu and kenya the december 26 2004 sumatra tsunami caused severe damage at the coasts of the indian ocean we report results of a sedimentological study of tsunami run up parameters and the sediments laid down by the tsunami at the coast of tamil nadu india and between malindi and lamu kenya in india evidence of three tsunami waves is preserved on the beaches in the form of characteristic debris accumulations we measured the maximum run up distance at 580 m and the maximum run up height at 4 85 m flow depth over land was at least 3 5 m the tsunami deposited an up to 30 cm thick blanket of moderately well to well sorted coarse and medium sand that overlies older beach deposits or soil with an erosional unconformity the sand sheet thins inland without a decrease of grain size the deposits consist frequently of three layers the lower one may be cross bedded with foresets dipping landward and indicating deposition during run up the overlying two sand layers are graded or parallel laminated without indicators of current directions thus it remains undecided whether they formed during run up or return flow thin dark laminae rich in heavy minerals frequently mark the contacts between successive layers benthic foraminifera indicate an entrainment of sediment by the tsunami from water depths less than ca 30 m water depth on the indian shelf these depths are present at distances of up to 5 km from the coast in kenya only one wave is recorded which attained a run up height of 3 m at a run up distance of ca 35 m from the tidal water line at the time of the tsunami impact only one layer of fine sand was deposited by the tsunami it consists predominantly of heavy minerals supplied to the sea by a nearby river the sand layer thins landward with a minor decrease in grain size benthic foraminifera indicate an entrainment of sediment by the tsunami from water depths less than ca 30 m water depth reaching down potentially to ca 80 m the presence of only one tsunami related sediment layer in kenya but three in india reflects the impact of only one wave at the coast of kenya as opposed to several in india grain size distributions in the indian and kenyan deposits are mostly normal to slightly positively skewed and indicate that the detritus was entrained by the tsunami from well sorted pre tsunami deposits in nearshore swash zone and beach environments

petrology of two diamondiferous eclogite xenoliths from the lahtojoki kimberlite pipe eastern finland abstract diamondiferous group a eclogites constitute a minor portion of the mantle derived xenoliths in the eastern finland kimberlites they have been derived from the depth interval 150 230 km where they are inferred to occur as thin layers or small pods within coarse grained garnet peridotites the chemical and isotopic composition of minerals suggest that they represent proterozoic mantle derived melts or cumulates rather than subducted oceanic lithosphere during magma ascent and emplacement of the kimberlites the eclogite xenoliths were mechanically and chemically rounded judging from the types of surface markings in addition those octahedral crystal faces of diamonds that were partially exposed from the rounded eclogite xenolith became covered by trigons and overlain by microlamination due to their reaction with the kimberlite magma the diamonds bear evidence of pervasive plastic deformation which is not however evident in the eclogite host this suggests that annealing at ambient lithospheric temperatures has effectively recrystallised the silicates while the diamond has retained its lattice imperfections and thus still has the potential to yield information about ancient mantle deformation one of our samples is estimated to contain approximately 90 000 ct ton diamond implying that some diamonds occur within very high grade pods or thin seams in the lithospheric mantle to our knowledge this is one of the most diamondiferous samples described

thermal evolution of the upper yangtze craton secular cooling and short lived thermal perturbations abstract the upper yangtze craton uyc has stayed in a long term stabilization state its thermal history can be portioned into two parts secular evolutionary trend and short lived thermal perturbations the former is simulated by a two dimensional forward transient thermal model and the latter is discussed by reviewing previous studies the numerical modeling indicates the uyc tended to be cooling as it adjusted to the asynchronous rates of change in the internal radiogenic heat production and in the convecting mantle temperature below the cratonic root the average cooling rate of the uyc has been 58 c ga since the end of archean faster than that of the convecting mantle the surface heat flow presents a decreasing trend from 82 mw m2 at 2 5 ga to 53 mw m2 at present day which constructs the long term evolutionary path the thermal perturbations derived from the occasional tectono thermal events such as mantle plume activity and regional lithosphere extension serves as paroxysmal factors the thermal effects of the emeishan mantle plume were very strong yielding to the maximum heat flow anomaly of 100 mw m2 at the late permian in contrast the influences of regional lithosphere extension during both the early paleozoic period and the early permian middle triassic period were rather weak resulting in a surface heat flow increase of

upper mantle structure of the baltic shield below the swedish national seismological network snsn resolved by teleseismic tomography summary upper mantle structure under the baltic shield is studied using non linear high resolution teleseismic p phase tomography observed relative arrival time residuals from 52 teleseismic earthquakes recorded by the swedish national seismological network snsn are inverted to delineate the structure of the upper mantle the network consists of 47 currently working three component broad band stations located in an area about 450 km wide and 1450 km long in order to reduce complications due to possible significant three dimensionality of earth structure events chosen for this study lay close to in line with the long axis of the array 30 results indicate p wave velocity perturbations of 3 per cent down to at least 470 km below the network the size of the array allows inversion for structures even at greater depths and lateral variations of velocity at depths of up to 680 km appear to be resolved below the central part of the array 60 64 n where ray coverage is best the data reveals a large region of relatively low velocity at depths of over about 300 km at depths less than about 250 300 km the models include a number of features including an apparent slab like structure dipping gently towards the north

geochemical and micropaleontological impacts caused by the 2011 tohoku oki tsunami in matsushima bay northeastern japan abstract we present stratigraphic geochemical cns elemental analysis and micropaleontological ostracode assemblages evidence for the 2011 tohoku oki tsunami impact in matsushima bay northeastern japan and examine the recovery process after the impact to the bay environment using short sediment cores from two different topographic settings at a water depth of approximately 4 m at both sites tsunami deposits are composed of two sedimentary layers that recorded the first tsunami run up and backwash at the western site near the channel that connects the bay with the pacific ocean the first tsunami wave eroded the bay floor sediments and left the tsunami deposits composed of medium sand rich in shell fragments but with sparse numbers of meiobenthic ostracodes by contrast at the eastern site which is surrounded by many small islands the first wave eroded very little of the bay floor sediments and left tsunami deposits consisting of sandy mud rich in exotic ostracodes such as phytal species shallow marine sand dwelling species and brackish water species overlying post tsunami deposits are composed mainly of organic rich mud in which organic matter was derived primarily from marine plankton ostracode assemblages in the tsunami deposits lack the offshore species that live in water depths 50 m and are dominated by the species from matsushima bay and its adjacent nearshore upper sublittoral areas and brackish water environments the distance from deep water offshore areas to the core sites is too far to transport ostracode valves by tsunami waves

the use of ostracods from marginal marine brackish waters as bioindicators of modern and quaternary environmental change abstract ostracoda microscopic aquatic crustacea from brackish waters have a great potential for ecological monitoring and palaeoenvironmental analyses in highly variable environments this has been proven in many articles during recent decades but their potential has yet to be fully developed or utilised the analysis of ostracod assemblage composition species distributions eco phenotypic variability and the analysis of stable isotopes and trace elements in ostracod shells provide valuable information on present and past water salinity temperature and chemistry hydrodynamic conditions substrate characteristics climate sea level variations oxygen and nutrient availability this article provides an overview on the application of ostracods from brackish waters for palaeoenvironmental reconstruction in the quaternary and for environmental studies in present day environments

holocene coastal change and geoarchaeology at howick northumberland uk the recent discovery of one of the earliest mesolithic occupation sites in northern britain at howick on the northumberland coast in association with multiperiod archaeological evidence nearby highlights the importance of uk coastal settings as focii of human occupation through the holocene environmental evidence from a nearby river valley 8 15 m of sediment ranging in age from about 12 000 cal bp to the present records local and regional environmental change twenty four radiocarbon dates based on plant macrofossils provide a strong chronological framework calcareous microfossil assemblages foraminifera ostracods have been recovered from the fine grained sediments recording a change from marine through to brackish and eventually freshwater conditions between about 8200 and 6500 cal bp a preliminary pollen study of the core has permitted a reconstruction of the regional vegetation as it responded to climatic amelioration and human influence upon the landscape radiocarbon dating and sedimentological evidence indicates a major hiatus between approximately 11 000 and 8000 years bp including the period of mesolithic occupation represented by a 30 cm layer of coarse sands and sandstone pebbles probably the result of a significant high energy event dated to about 8300 cal bp although not a typical tsunami deposit the age and context suggests that this may be associated with the storegga slide event already well documented along the eastern coast of scotland the sedimentary and biological remains at howick record environmental change over much of the holocene and are compared with other environmental change records from the region to provide an environmental framework for the archaeology of this coastline

sedimentation and hydrodynamic processes associated with the tsunami generated by the 1755 lisbon earthquake abstract an unusual sedimentary horizon believed to have been deposited by the tsunami associated with the 1755 lisbon earthquake has been identified at boca do rio in southern portugal this horizon marks a distinct sedimentological and micropalaeontological break from the deposits enclosing it the sedimentary characteristics of the horizon which consists of several distinct sub units vary greatly in both vertical and horizontal section detailed textural analysis through vertical sections of these sub units shows abrupt changes in particle size characteristics the highly variable nature of the horizon appears to be due to rapid variation in the hydrodynamic characteristics of the depositional event the lowermost section of the deposit appears to have been deposited from a highly turbulent water mass which was able to transport gravel sized clasts as well as gravel sized mud balls eroded from underlying material the water mass rapidly lost energy leading to the deposition of predominantly sand silt and clay particles sharp breaks in textural characteristics are likely to be due to changes in current direction caused by wave reflection or swash backwash interference the main sources of sand sized material within the deposit are the seaward barrier beach foredune system the tsunami deposit at boca do rio shares many of the sedimentary characteristics of tsunami deposits from other sites around the world

sedimentologic and geomorphologic tsunami imprints worldwide a review abstract tsunami events with extreme effects on sedimentary transport or considerable alterations of the coastal configuration are rather rare regarding human history but considering geological timescales they occur frequently at least 100 megatsunami in different parts of the world have been recorded in the past 2000 years but presumably far more have failed to be noticed during historical times and are not mentioned either in written or oral ancient records therefore the topic of paleotsunami requires inevitable sedimentological and geomorphological research however field research concerning paleotsunami is astonishingly rare within the scientific approach and only 5 of the existing tsunami literature is related to this subject future efforts in paleotsunami research should focus on the geological evidence of these mega events to clarify their contribution to coastal forming processes this paper reviews the state of the art knowledge of sedimentologic and geomorphic imprints of tsunami along the world s coastlines in order to highlight the need for more detailed studies of paleotsunami depositional and geomorphological traces

evidence of high energy events in the geological record mid holocene evolution of the southwestern donana national park sw spain abstract four phases are distinguished in the mid holocene evolution of the southwestern donana national park sw spain based on the multidisciplinary study of sediments in drill cores in the oldest phase 5500 5400 cal years bp a coastal brackish lagoon occupied the central part of the study area partly enclosed by the donana spit and limited by fluvial levees an evolution from subtidal to intertidal conditions characterized the areas located close to the inner side of the donana spit during the same phase the following phase 5400 5200 cal years bp is characterized by a high energy event tsunami which caused the breakthrough of the donana spit and the creation of new littoral strands in the inner areas in the first period of the third phase 5200 4200 cal years bp estuarine infilling was probably the dominant process with the accumulation of phyllosilicate rich clays in the lagoon bed this was followed by a renewed phase of instability 4200 4100 cal years bp indicated by the presence of fine storm lain deposits and thicker probably tsunami induced shelly deposits the last phase 4100 3700 cal years bp comprises a an infilling period with a diminution of the marine influence and b two new high energy events which caused the erosion of the donana spit and the creation of new cheniers in the last 7000 years the comparison of these results with a revision of both geological and historical records has revealed the occurrence of twenty tsunamis at least during this period in portugal and southern spain evidences of these high energy events are washover fans bioclastic coarse sized layers within salt marsh deposits or the presence of giant boulders and pebbles the determination of the recurrence period is very difficult owing to the very scarce data although our data and other authors do not discard a possible periodicity of 2000 years for a cycle of two events separated by 300 400 years

radiogenic heat production in the lithosphere of sulu ultrahigh pressure metamorphic belt abstract the chinese continental scientific drilling ccsd project is located at the sulu ultrahigh pressure metamorphic uhpm belt it offers a unique opportunity for studying the radiogenic heat production of both shallower and deeper rocks based on the concentrations of radiogenic elements u th and k on 349 samples from main hole of ccsd ccsd mh pilot holes and exposures we determined radiogenic heat productions of all major rock types in the sulu uhpm belt results show the mean values of orthogneiss and paragneiss are respectively 1 65 0 81 and 1 24 0 61 w m 3 due to different composition and grade of retrogressive metamorphism the eclogites display significant scatter in radiogenic heat production ranging from 0 01 to 2 85 w m 3 with a mean of 0 44 0 55 w m 3 the radiogenic heat production in ultramafic rocks also varies within a large range of 0 02 to 1 76 w m 3 and the average turns out to be 0 18 0 31 w m 3 based on the measurements and crustal petrologic model the vertical distribution model of heat production in sulu crust is established the resulting mean heat production 0 76 w m 3 contributes 24 mw m 2 to the surface heat flow 1 d thermal model indicates that the temperature at the moho reaches above 750 c and the thermal thickness of the lithosphere is 75 km in good agreement with the geophysical results the high teat flow 75 mw m 2 together with thin lithosphere presents strong support for the extension events during the late cretaceous and cenozoic

facies analysis foraminiferal record and chronostratigraphy of holocene sequences from saltes island tinto odiel estuary sw spain the origin of high energy deposits abstract a multidisciplinary analysis of holocene sediments from la cascajera tinto odiel estuary sw spain has allowed to differentiate five sedimentary facies sandy tidal flat clayey tidal flat washover fan salt marsh edaphic horizon according to their granulometric characteristics internal structure mineralogical composition clay mineral assemblage and paleontological record these data coupled to 14c ams dating suggest an evolution from a sandy tidal plain to a chenier before 2100 cal yr bp this initial chenier was partially eroded later by regional storms between 2100 cal yr bp and 1900 cal yr bp leading to the deposition of two washover fans these facies have been eroded in the last centuries by the action of an ebb tide channel

a global analysis of heat flow from precambrian terrains implications for the thermal structure of archean and proterozoic lithosphere previous studies of heat flow from precambrian terrains have yielded two different relationships a global temporal relationship between heat flow and tectonic age and a regional spatial relationship between heat flow and the proximity of archean cratons we analyze heat flow from tectonically stable precambrian terrains worldwide to address questions associated with these two heat flow patterns 1 is the spatial relationship a global pattern 2 do the two heat flow relationships have a common underpinning in answer to the first question our data analysis reveals a widespread spatial pattern between heat flow and the proximity of archean cratons which is characterized by low heat flow in archean cratons and proterozoic terrains adjacent to cratonic margins and higher heat flow in proterozoic terrains that are more than a few hundred kilometers from a craton to address the second question we examine three previous interpretative models of precambrian heat flow 1 simple cooling of a thermal boundary layer 2 thicker lithosphere in archean terrains than in proterozoic and 3 greater heat production in proterozoic crust than in archean model 1 predicts essentially no change in heat flow in terrains older than 1 5 ga and therefore does not likely provide a common underpinning for the precambrian heat flow patterns models 2 and 3 when combined with the special structural configuration of sutures can independently yield both the spatial and temporal heat flow distributions and thus alone or together may be considered candidates to explain the precambrian heat flow patterns however thermal models of the lithosphere in which the heat flow patterns are explained entirely by variations in crustal heat production cannot satisfy constraints on upper mantle temperatures beneath archean cratons derived from xenolith thermobarometry the thermobarometry constraints can be satisfied by models in which differences in lithospheric thickness are the principal factor controlling the surface heat flow distributions if the heat flow patterns result primarily from variations in lithospheric thickness then a different temporal heat flow relationship for precambrian terrains can be proposed one in which heat flow varies inversely with the age of stabilization of the lithosphere

a tsunami ca 6300 years bp and other holocene environmental changes northern hawke s bay new zealand abstract sediment cores collected in a coastal lagoon a few kilometres east of wairoa northern hawke s bay new zealand were examined using sedimentological geochemical palynological and micropaleontological analyses a distinct short lived catastrophic saltwater inundation csi about 6300 years bp and possibly other minor marine incursions are preserved in the coastal estuarine to lagoonal freshwater sedimentary sequences which have been deposited in the last 6500 years the csi is characterised by a gravel unit that thins landward and decreases in particle size to sand within a sequence consisting mainly of brackish estuarine muds diatom assemblages indicate a marked change from the shallow brackish estuarine muds to marine gravels and sands to brackish estuarine muds the marine influence in the gravel and sand is also shown by the presence of marine dinoflagellates and a peak in na rb sedimentological chemical and paleontological in particular diatoms evidence indicates it is a csi we conclude that this was a tsunami and propose the most likely propagating mechanisms marine influence decreases upcore and totally freshwater conditions are evident in the upper section of the cores the geochemistry of the sediments mainly reflects the change in stratigraphy with distinct signatures for tephra na fe cr organic rich and peat units as br and the coarse gravel sand csi unit na rb cr fe but it is also indicative of changes in depositional environment the change in chemistry na rb in the csi event is indicative of a saltwater influence whereas a marked change in s content suggests a sudden change from brackish to freshwater conditions shortly after 4800 years bp another peak in s and br content about 3200 years bp may indicate another temporary change to brackish conditions

carbonate platform growth and cyclicity at a terminal proterozoic passive margin infra krol formation and krol group lesser himalaya india the infra krol formation and overlying krol group constitute a thick 2 km carbonate rich succession of terminal proterozoic age that crops out in a series of doubly plunging synclines in the lesser himalaya of northern india the rocks include 18 carbonate and siliciclastic facies which are grouped into eight facies associations 1 deep subtidal 2 shallow subtidal 3 sand shoal 4 peritidal carbonate complex 5 lagoonal 6 peritidal siliciclastic carbonate 7 incised valley fill and 8 karstic fill the stromatolite rich peritidal complex appears to have occupied a location seaward of a broad lagoon an arrangement reminiscent of many phanerozoic and proterozoic platforms growth of this complex was accretionary to progradational in response to changes in siliciclastic influx from the south eastern side of the lagoon metre scale cycles tend to be laterally discontinuous and are interpreted as mainly autogenic variations in the number of both sets of cycles and component metre scale cycles across the platform may result from differential subsidence of the interpreted passive margin apparently non cyclic intervals with shallow water features may indicate facies migration that was limited compared with the dimensions of facies belts correlation of these facies associations in a sequence stratigraphic framework suggests that the infra krol formation and krol group represent a north to north westfacing platform with a morphology that evolved from a siliciclastic ramp to carbonate ramp to peritidal rimmed shelf and finally to open shelf this interpretation differs significantly from the published scheme of a basin centred on the lesser himalaya with virtually the entire infra krol krol succession representing sedimentation in a persistent tidal flat environment this study provides a detailed neoproterozoic depositional history of northern india from rift basin to passive margin and predicts that genetically related neoproterozoic deposits if they are present in the high himalaya are composed mainly of slope basinal facies characterized by fine grained siliciclastic and detrital carbonate rocks lithologically different from those of the lesser himalaya

ostracod palaeolimnological analysis reveals drastic historical changes in salinity eutrophication and biodiversity loss in a coastal mediterranean lake the albufera of valencia one of the largest oligohaline coastal lagoons of the iberian peninsula has suffered hydrological and landscape modifications since medieval times this paleolimnological study clears up the controversy about the factors which drove the lake to its present state lithological descriptions ostracod paleoassemblages and cyprideis torosa jones 1850 shell morphological variations and geochemistry 18o 13c and sr ca have been used to reconstruct the lake ecosystem evolution during the last two centuries the sandy sediments at the bottom of l antina core 63 cm presented a typical assemblage of brackish water ostracods with shell derived 18o values inferred salinity and sr cawater characteristic of waters with marine influence however 10 cm above coinciding with a drastic change in lithology ostracod palaeoassemblages and decreased shell 18o indicated a shift to freshwater influences at the top of the sequence inferred salinity suggests oligohaline waters and ostr

the lithosphere asthenosphere system in fennoscandia abstract we present a summary of the available information on rayleigh wave dispersion data for the fennoscandian region the observations have been combined to produce regional dispersion relations which have then been subjected to the hedgehog inversion procedure the results are presented on a map outlining the thickness of the lid and the shear velocities in both the lid and the asthenosphere channel lid thickness up to around 135 km is found in the bothnia north central finland area with if any weak shear velocity contrast to the underlying layer the surrounding areas are characterized by lid thickness up to around 75 km a stronger low velocity zone to lid contrast may be found in the caledonian and baltic sea area 0 25 0 45 km s taking into account moho depth data and the aforementioned results a map of the lithosphere asthenosphere system was derived

tsunami deposits in holocene bay mud in southern kanto region pacific coast of central japan abstract tsunami have probably deposited sand sheets that are intercalated in holocene bay floor mud exposed on the boso and miura peninsulas facing the convergent boundary of the pacific philippine sea and eurasian plates we have identified seven sand sheets at four drowned valleys and correlated these by 137 radiocarbon dates of shells and wood the sheets consist of poorly sorted muddy sand and well sorted sand layers in fining upward sequences containing abundant transported shells rip up clasts and wood fragments the sheets erosionally overlie bioturbated bay floor mud that contains molluscan shells in life position most of the sheets are less than 20 cm thick and rarely more than 50 cm thick some molluscan shells are older in these layers than in underlying mud both landward and seaward paleocurrents are shown in a few cases by imbrication of shells and by low angle wedge shaped lamination at least five of the sand sheets contain molluscan fossils derived from rocky coasts or shore platforms although they intercalated in mud deposited within bays at depths of 10 15 m two other sand sheets are dominated by open seashore ostracode assemblages although they were deposited in the brackish inner bay and muddy central bay five of the layers may correlate with emergences recorded by nearby holocene marine terraces these correlations suggest that great earthquakes triggered the inferred tsunami the tsunami occurred at intervals of 300 2000 years beginning about 10 000 years ago

terrestrial heat flow and radiogenic heat production in finland the central baltic shield abstract heat flow density and radiogenic heat production of the bedrock were studied in finland in part of the central baltic fennoscandian shield heat flow data were collected from 35 holes 270 1080 m deep the heat production values at the sites were determined from the drill core samples by gamma ray spectrometry the areal variation in heat production was studied with the aid of k u and th analyses of 1054 glacial till samples collected for the geochemical atlas of finland a heat production map constructed from this data set revealed a strong areal variation that can be attributed to the known lithological geochemical and tectonic features of the bedrock in general heat production seems to increase with decreasing geological age the presented data strongly suggest that the southern and western parts of finland are geothermally anomalous apparent heat flow density 38 68 mw m 2 surface heat production 2 0 w m 3 in contrast to the other parts of the country mw m 2 w m 3 the heat production heat flow density plots were constructed from apparent and palaeoclimatically corrected heat flow densities the heat production values were determined from both drill core samples and till samples the plot constructed from the till data and apparent heat flow densities which yielded a scale depth of 10 8 2 6 km and a reduced heat flow density of 15 8 4 9 mw m 2 was considered the most reliable the results are discussed in terms of crustal fracturing and deep groundwater flow if the crystalline bedrock is approached as a medium consisting of blocks internally conductive but bounded by fracture zones in which heat is transported by groundwater flow an alternative hypothesis can be constructed for interpreting the linear heat production heat flow density plots according to this hypothesis the scale depth and reduced heat flow densities refer only to the geothermal properties of the uppermost bedrock block in the present study this concept is supported by results from deep electromagnetic and seismic soundings

heat production in the continental crust part i data converted from seismic velocities and their attempted interpretation abstract when using the simple exponential distribution of radiogenic heat production a with depth z a z a o exp z d the statistical analysis of a large number of heat production profiles converted from the observed seismic velocity vs depth profiles and the experimental knowledge of the relationship between seismic velocity and heat production disclosed certain relations between the logarithmic decrement d value and heat flow tectonic age and crustal thickness the d valuein this respect characterizes the depth rate of the differentiation of the heat production in all tectonic units the d parameter decreases with depth as the next step the more complicated distribution law a z a o exp z d a was applied where a characterizes the quantity of removed heat sources by the processes accompanying the crustal evolution such as remelting metamorphosis leaching by underground waters etc all parameters a o a and d are constant within each particular tectonic province and parameter d does not depend on depth contrary to the former law the amount of removed heat sources a reflects the initial concentration of heat sources and is higher in young tectonic terranes in areas of high heat flow and in regions of thin crust

geophysical constraints on partial melt in the upper mantle this paper addresses the conditions under which partial melt can exist in the mantle in order to be observed as a geophysical anomaly typical observed anomalies are high electrical conductivity of the order of 0 1 s m or greater velocity decreases of 7 10 seismic q values less than 100 and a frequency band for seismic effects in the region near 1 hz existing theories of electrical conduction in partial melts and of frequency dependent seismic properties together with recent measurements of melt electrical conductivity viscosity and partial melt texture can be used to establish requirements for melt to be observed by geophysical methods from electrical anomalies mainly sensitive to melt volume and its interconnection one can require a minimum melt fraction of several percent at temperatures close to the solidus 1150 1300 c however seismic models demand only a small volume in very flattened shapes aspect ratio 0 001 melt fraction 0 1 further if melt configuration permits seismic dissipation in bulk that is there exist flattened voids intersecting more or less equant voids then it is possible to infer melt fractions for elastic anomalies that are consistent with the several percent required for electrical anomalies observed equilibrium textures of partly melted peridotite together with inferred melt solid surface energies suggest that melt on a grain size scale in a gravitational field segregates into a strongly anisotropic pattern thus if partial melt causes mantle geophysical anomalies it should exist in a variety of void shapes and probably of sizes while the association of electrical and elastic anomalies with indications of reduced density volcanism and high heat flow makes the hypothesis of partial melting an attractive explanation the minimum physical requirement is for existence of relatively high temperature

diatom biostratigraphy of tsunami deposits examples from the 1998 papua new guinea tsunami abstract distinctive diatom assemblages may be associated with tsunami sediments and may often contrast with the assemblages found within sediments underlying the tsunami deposit as well as those associated with the modern coastal environment sediments associated with the 1998 tsunami that destroyed much of the sissano lagoon area in northern papua new guinea have been investigated surface sediments from three transects across the sediment spit near warapu have been examined for diatom content and preservation the preservation is variable and the data show an often chaotic assemblage that can be attributed to the tsunami waves incorporating and depositing diatoms from distinctive habitat zones during their runup and subsequent backwash the diatoms identified within the warapu sediments indicate an origin from within the inter tidal and offshore area rather than from the beach sand spit complex the sand deposits disclose a high percentage in excess of 75 of broken diatom valves and a predominance of centric circular species due to preferential preservation the study demonstrates that the application of diatom biostratigraphy to modern tsunami deposits can be used in conjunction with other stratigraphical lines of evidence to interpret the source and provenance of historical and palaeo tsunami deposits