climate instability during the last interglacial period recorded in the grip ice core isotope and chemical analyses of the grip ice core from summit central greenland reveal that climate in greenland during the last interglacial period was characterized by a series of severe cold periods which began extremely rapidly and lasted from decades to centuries as the last interglacial seems to have been slightly warmer than the present one its unstable climate raises questions about the effects of future global warming

the february 11 2004 dead sea earthquake ml 5 2 in jordan and its tectonic implication abstract a moderate sized m w 5 3 earthquake occurred in the dead sea basin on february 11 2004 a rigorous seismological analysis of the main shock and numerous aftershocks suggests that seismogenic structure was a secondary antithetic fault within the dead sea fault system the main shock is well located using all available regional seismic stations and 43 aftershocks were precisely located relative to the main shock using a double difference algorithm the first motion focal mechanism for this earthquake demonstrates nnw sse and ene wsw striking nodal planes and the aftershocks distribution is consistent with the latter indicating a right lateral sense of displacement this orientation and sense of shear are consistent with similarly oriented geological faults around the dead sea basin these structures are likely antithetic faults within the transform system although moderate in size earthquakes that occur very close to the large dead sea fault system warrant consideration in the earthquake hazard assessment of the region for example owing to the proximity to the main fault moderate earthquakes such as this may produce static changes in coulomb stress along the main fault

holocene paleoceanography of the northwest passage canadian arctic archipelago abstract a series of cores box and piston were collected at 2 key locations in lancaster sound cores 2004 804 009 bc and pc and barrow strait cores 2005 804 004 bc and pc in the canadian arctic archipelago to document the evolution of sea surface conditions in the main axis of the northwest passage during the holocene time period reconstruction of sea surface parameters summer temperature and salinity duration of sea ice cover were estimated based on transfer functions using dinoflagellate cyst assemblages as proxy indicators the chronology of these cores is based on calibrated ams 14c dates 210pb analyses and correlations between paleomagnetic secular variations of the geomagnetic field and a predicted spherical harmonic model of the geomagnetic field cals7 k 2 our age models for both cores indicate that 009 pc spans the last 11 100 cal bp while 004 pc encompasses the last 10 800 cal bp calculated sedimentation rates are in the range of 43 140 cm kyr for core 009 pc and 15 118 cm kyr for core 004 pc allowing for a millennial time scale resolution in each core our results indicate relatively harsh conditions in lancaster sound between 10 800 and 9000 cal bp summer temperatures 2 c cooler than at present which we associate with the presence of active ice streams in northernmost baffin bay and a weak west greenland current this is followed by a warming trend up to 3 c higher than present that took place between 8500 and 5500 cal bp which we associate with the holocene thermal maximum and to a large scale atmospheric pattern such as the arctic oscillation operating at the millennial time scale this is concomitant with an increase in the relative abundance of phototrophic dinoflagellate cyst taxa a gradual cooling of sea surface temperature and increased sea ice follow this from 5500 cal bp until the modern period in barrow strait harsh sea surface conditions prevailed from 11 100 to 5500 cal bp with summer temperatures as low as 4 c cooler than at present the warming trend occurred later in this region between 5500 and 1000 cal bp after which a gradual cooling is observed until the modern period the apparent shift or opposite warming trends between lancaster sound and barrow strait after 5500 cal bp could be the result of a change in atmospheric circulation patterns related to a possible shift in the ao mode from ao to ao comparison of ice core 18o record from devon island ice cap and the reconstructed sea surface temperature from core 009 pc suggests a strong atmospheric oceanic coupling throughout the holocene in this area

seismotectonics and seismology in the arab region a brief summary and future plans abstract the arab region extending from morocco to iraq has experienced some of the worst earthquake disasters of recent times yet much is still not understood of its tectonic environment and its seismological recording network needs much expansion and improvement the region contains such diverse tectonic regimes as the continental collision along the zagros fold and thrust belt in northeast iraq and along the rif and atlas mountain belts of morocco algeria and tunisia the active sea floor spreading in the red sea and the gulf of aden and the remarkable structure of the dead sea transform fault system we present a brief summary of the seismotectonics of these areas and their relation to earthquake occurrence the seismological recording networks in the different arab countries are also extremely diverse in quality and distribution of instruments in some countries such as algeria djibouti egypt iraq and morocco seismology is already well established in others such as jordan or saudi arabia there are either isolated stations or plans for a network while in libya sudan and syria there is as yet no seismological recording we discuss plans for the future development of seismological recording throughout the arab region

latest quaternary and holocene paleoceanography of the eastern baffin island continental shelf canada benthic foraminiferal evidence foraminiferal zones radiocarbon ages on shells and corrected ages on pretreated organic sediment from four cores from the eastern baffin island continental shelf suggest a three stage deglacial to postglacial history late wisconsin to holocene the earliest sediments in the cores contain foraminiferal species elphidium excavatum cassidulina reniforme islandiella helenae indicative of distal glaciomarine environments that lasted at least several thousand years an oceanographic change about 8500 years ago is indicated by a melonis zaandamae zone in northern and central shelf cores collected from 200 800 m water depth the presence of m zaandamae in the north and its absence in the south suggest warmer and more saline postglacial water in northern baffin bay whose influence became diluted with cooler coastal meltwater as the current flowed south along the baffin island shelf sediments after 6000 years ago on the northern and central shelf are dominated by agglutinated foraminifera suggesting dis

spatial and temporal distribution of soil organic carbon in nonsorted striped patterned ground of the high arctic 1 the role of periglacial processes on soil carbon distribution is examined at a high arctic site in northwest greenland a 16 m trench dug across a series of nonsorted stripes at thule air base revealed sand rich wedges underlying striped vegetated troughs and organic rich soil horizons buried at depth the site has sparse prostrate vegetation and is estimated to contain 9 4 kg m 2 of soil organic carbon soc in the active layer the distribution of carbon is variable with nearly half 49 stored in the sand wedges which only account for 10 of the trench area additionally 62 of the total soc was found below 25 cm highlighting the significant role of cryoturbation and physical redistribution of carbon in permafrost affected soils carbon in the active sand rich wedges dates from modem at the surface 65 35 radiocarbon years to 2695 40 radiocarbon years at depth and carbon turnover time appears to be 450 years buried organic horizons found at 50 70 cm depth have radiocarbon ages of 27 480 31 900 bp a conceptual model is proposed in which the active sand wedges have developed in an approximately 30 ka surface containing buried soils preserved in permafrost or under a cold based glacier as the ice retreated and soils warmed soil development and active cryoturbation resumed forming nonsorted stripes in the modern surface

faulting associated with historical and recent earthquakes in the eastern mediterranean region summary this paper summarizes evidence for surface faulting in historical and recent earthquakes in the eastern mediterranean region and in the middle east such information is particularly important for studies of active tectonics and for palaeoseismology we have found 78 cases of faulting pre 1900 and 72 post 1900 some of which show that faults that have apparently been inactive this century had already ruptured before 1900 for some cases faulting could not have been predicted from 20th century activity and in others it could have been expected but has not been observed during the instrumental period the data are suycient to allow the derivation of relationships between magnitude and rupture length

new empirical relationships among magnitude rupture length rupture width rupture area and surface displacement source parameters for historical earthquakes worldwide are compiled to develop a series of empirical relationships among moment magnitude m surface rupture length subsurface rupture length downdip rupture width rupture area and maximum and average displacement per event the resulting data base is a significant update of previous compilations and includes the additional source parameters of seismic moment moment magnitude subsurface rupture length downdip rupture width and average surface displacement each source parameter is classified as reliable or unreliable based on our evaluation of the accuracy of individual values only the reliable source parameters are used in the final analyses in comparing source parameters we note the following trends 1 generally the length of rupture at the surface is equal to 75 of the subsurface rupture length however the ratio of surface rupture length to subsurface rupture length increases with magnitude 2 the average surface displacement per event is about one half the maximum surface displacement per event and 3 the average subsurface displacement on the fault plane is less than the maximum surface displacement but more than the average surface displacement thus for most earthquakes in this data base slip on the fault plane at seismogenic depths is manifested by similar displacements at the surface log linear regressions between earthquake magnitude and surface rupture length subsurface rupture length and rupture area are especially well correlated showing standard deviations of 0 25 to 0 35 magnitude units most relationships are not statistically different at a 95 significance level as a function of the style of faulting thus we consider the regressions for all slip types to be appropriate for most applications regressions between magnitude and displacement magnitude and rupture width and between displacement and rupture length are less well correlated and have larger standard deviation than regressions between magnitude and length or area the large number of data points in most of these regressions and their statistical stability suggest that they are unlikely to change significantly in response to additional data separating the data according to extensional and compressional tectonic environments neither provides statistically different results nor improves the statistical significance of the regressions regressions for cases in which earthquake magnitude is either the independent or the dependent parameter can be used to estimate maximum earthquake magnitudes both for surface faults and for subsurface seismic sources such as blind faults and to estimate the expected surface displacement along a fault for a given size earthquake

the structure of the dead sea basin abstract the dead sea basin is located along the left lateral transform boundary between the arabian and sinai plates its structure and history are known from surface geology drilling seismic reflection and other geophysical data the basin comprises a large pull apart almost 150 km long and mostly 8 10 km wide which is flanked by a few kilometres wide zones of normal faulting the basin formed at about 15 ma or earlier close to the beginning of the transform motion and it reached about half its present length before the end of the miocene a strong negative gravity anomaly records a thick sediment basin fill 5 km under half its length reaching a maximum of 10 km the fill includes a few km of salt ca 6 4 ma which forms several diapirs at any one time large parts of the basin subsided simultaneously but the site of fastest subsidence seems to have shifted northward sedimentation rates reached at least hundreds of metres per million years or more in the miocene and 1 km myr in later periods the basin structure is dominated by longitudinal faults intrabasinal faults which delimit the pull apart and which are the extensions of the major strike slip faults north and south of the basin and normal faults which extend along the basin margins the latter faults express a small component of extension across the basin whereas the pull apart resulted from the much larger lateral motion along the basin in addition transverse faults divide the pull apart into several segments with somewhat different histories the pull apart grew by becoming longer parallel to the transform motion at shallow levels this was probably achieved by normal slip on transverse listric faults while the fill between them was little deformed the crust under the basin was stretched and thinned during basin lengthening which caused its subsidence basin formation was accompanied by uplifting of its flanks by 1 km sparse igneous activity occurred along the basin and its flanks its presence suggests a thermal anomaly in the lower lithosphere beneath the basin and adjacent parts of the transform

landscape chronology and glacial history in thule northwest greenland abstract constraining past responses of ice sheets to changes in climate enhances our ability to predict future changes in ice extent and sea level here we employ surficial geologic mapping stratigraphic analysis radiocarbon dating of marine mollusks and analysis of cosmogenic 10 be in glacially deposited boulders to make inferences about past ice extents in thule northwest greenland our work shows the existence of two distinct diamict units in the thule area we infer that one diamict was deposited by the main greenland ice sheet while the second was deposited by a subsequent outlet glacier re advance boulders in the two diamicts n 13 and n 15 respectively have similar bimodal distributions of cosmogenic 10 be ages both diamicts have a group of younger 10 be ages as well as a more diffuse group of considerably older 10 be ages 20 30 ka many of the boulders likely contain nuclides inherited from previous periods of exposure suggesting that glacial ice in the thule region has been cold based and non erosive in the past the landscape chronology we develop suggests that deglaciation after the last glacial maximum occurred 10 8 ka and was later followed by a re advance of outlet glaciers possibly in concert with the 9 3 ka or 8 2 ka cold events

quaternary glacial and marine environmental history of northwest greenland a review and reappraisal new information on middle and late quaternary deposits of the thule region northwest greenland necessitates the revision of the chronostratigraphy of the area and allows fuller understanding of the marine environmental changes in ba n bay the stratigraphic record is interpreted as the product of three marine events saunders qarmat and nuna in decreasing age during which marine sedimentation occurred on coastal areas now land and three or four glacial events of decreasing age and ice cover agpat narsaarsuk and kap abernathy wolstenholme fjord to which the marine events were glacio isostatically related subarctic atlantic water reached this northern part of ba n bay during all three marine events but the warmest conditions warmer than the present occurred in the qarmat event correlated with the deep sea oxygen isotope stage 5e the question of late stage 5 events is considered the nuna event dates to latest stage 2 and the holocene whilst the saunders event is of uncertain age but at least stage 6 a number of glacial events with advances confined to the fjords are dated to stage 2 wolstenholme fjord and late stage 6 narsaarsuk and an intermediate advance kap abernathy is undated in the range of stage 2 5 extension of glaciation to the shelf edge is dated to stage 6 agpat event 1999 elsevier science ltd all rights reserved

high resolution geological record of historic earthquakes in the dead sea basin a 2000 year paleoseismic record of the dead sea area was recovered from a lacustrine sedimentary section the section is being exposed at the ze elim terrace on the shores of the dead sea due to the fast retreat of the lake the section consists of laminated detrital and chemical mainly aragonite sediments that were deposited in the holocene paleo dead sea eight layers in the section show deformed sedimentary structures and are identified as seismites their chronology was determined by radiocarbon dating on organic remains the seismite ages are well correlated with the historically documented earthquakes of 64 and 31 b c and 33 363 1212 1293 1834 and 1927 a d the few historically documented earthquakes that have no correlatives in the ze elim seismite record occurred in times of sedimentary hiatuses at this site e g 749 a d based on modern analogues and the association of similar disturbed layers with syndepositional faults the ze elim terrace seismites indicate m 5 5 earthquakes the average recurrence interval is estimated as 100 300 years and represents slip events on different faults in the dead sea area the ze elim section provides a unique opportunity to correlate two independent and extensive data sets the historical and sedimentary records this study opens the way for better understanding of spatial and temporal distribution of earthquakes along the dead sea transform and elsewhere

episodic behavior of the jordan valley section of the dead sea fault inferred from a 14 ka long integrated catalog of large earthquakes the continuous record of large surface rupturing earthquakes along the dead sea fault brings unprecedented insights for paleoseismic and archaeoseismic research in most recent studies paleoseismic trenching documents the late holocene faulting activity while tectonic geomorphology addresses the long term behavior 10 ka with a tendency to smooth the effect of individual earthquake rupture events m w 7 here we combine historical archaeological and paleoseismic investigations to build a consolidated catalog of destructive surface rupturing earthquakes for the last 14 ka along the left lateral jordan valley fault segment the 120 km long fault segment limited to the north and the south by major pull apart basins the hula and the dead sea respectively is mapped in detail and shows five subsegments with narrow stepovers width 3 km we conducted quantitative geomorphology along the fault measured more than 20 offset drainages excavated four trenches at two sites and investigated archaeological sites with seismic damage in the jordan valley our results in paleoseismic trenching with 28 radiocarbon datings and the archaeoseismology at tell saydiyeh supplemented with a rich historical seismic record document 12 surface rupturing events along the fault segment with a mean interval of 1160 yr and an average 5 mm yr slip rate for the last 25 ka the most complete part of the catalog indicates recurrence intervals that vary from 280 yr to 1500 yr with a median value of 790 yr and suggests an episodic behavior for the jordan valley fault our study allows a better constraint of the seismic cycle and related short term variations late holocene versus long term behavior holocene and late pleistocene of a major continental transform fault

palynostratigraphy and chronostratigraphy of baffin bay deep sea cores climatostratigraphic implications abstract palynostratigraphic considerations and 14c dates ams accelerator mass spectrometry on foraminifera samples from piston cores suggest sedimentation rates as high as ca 8 11 cm ka in deep baffin bay during the late pleistocene throughout this interval baffin bay experiences rigorous conditions and probably the extension of a dense sea ice cover unfavourable to phytoplanktonic productivity the dinocyst microflora indicates only brief episodes of higher productivity related to arctic conditions and to moderately low salinites ca 30 31 the abundance of reworked pre quaternary palynomorphs in the deposits is interpreted as a response to glacial and glacio marine activity in the northernmost areas surrounding baffin bay the dinocyst stratigraphy spanning approximately over the last ice age ca 100 ka reveals that baffin bay constituted a confined basin isolated from the north atlantic ocean prior to the present interglacial

holocene emergence at cape herschel east central ellesmere island arctic canada implications for ice sheet configuration twenty five radiocarbon age determinations on marine molluscs basal organic pond sediments charred remains in archeological sites and a variety of other materials have allowed the construction of an emergence curve for cape herschel east central ellesmere island 78 35 n 74 40 w only a narrow fringe of land is present between the prince of wales icefield and smith sound yet emergence of the order of 135 m has taken place during the last 8500 8700 radiocarbon years the highest in situ shells were collected at an elevation of 107 5 m and ages of 8470 100 bp gsc 3314 and 8230 70 bp to 230 were obtained on this material the spectacular and fresh appearing glacial sculpture along both sides of smith sound coupled with the rapid emergence in holocene time and the fact that the oldest dates on marine shells at the fiord heads to the west are 3000 4000 years younger than those at cape herschel provides convincing evidence that an ice stream filled smith sound 500 m deep during the late wis

gps measurements of near field deformation along the southern dead sea fault system 1 analysis of short term deformation along the southern part of dead sea fault dsf provides a systematic view of kinematics this part of the continental transform the southern dsf consists of two principal segments the wadi araba and jordan valley faults in addition to other regional continuous gps data this study uses new data from 25 survey sites and 4 continuous gps stations in jordan for improved near field observations resulting velocities are reported with 1 uncertainties ranging from 0 4 1 0 mm yr application of elastic dislocation models yields estimates of slip rates for wadi araba and jordan valley faults are 4 9 0 4 mm yr and 4 7 0 4 mm yr respectively modeling also suggests different depths of effective fault locking with 15 5 km and 8 5 km for the wadi araba and jordan valley faults respectively these slip rates are generally consistent with the upper end of the range of slip rates estimated from late quaternary geology spatial variations in effective fault locking generally correspond with a heterogeneous mantle lithosphere a similar observation can be observed along the southern san andreas fault and this may reflect the influence of heterogeneity in the uppermost mantle on crustal faulting processes

four thousand years of seismicity along the dead sea rift a study of major earthquake occurrence along the dead sea transform 35 5 36 5 e 27 2 37 5 n during the past four millenia has been attempted geological archaeological biblical historical and seismological evidence were integrated in an effort to quantify the space time distribution of seismicity in the said province the overall earthquake activity in the conterminous near east indicates a stable pattern and appeared to have been stationary over the examined time window about 110 earthquakes in the magnitude range 6 7 ml 8 3 affected the area during the past 2500 years of these 42 originated along the dead sea fault system itself while 68 were imported from the helenic cyprian arcs and the anatolian elburz zagros fault systems these events were responsible for the repeated destruction of many cultural centers in the dead sea region proper the major seismic activity since 2100 b c e before christian era has been confined to the vicinity of its eastern shore with extremal seismicity at its southern tip near the prehistorical site of bab a dara a 31 15 n 35 32 e this may constitute the first solid evidence that the biblical cities of the plain sodom gommorah etc were located there recent studies of earthquake deformations in the lisan deposits near bab a dara a agree with our findings at the present time a magnitude 6 earthquake is pending at the northern edge of the levant rift with its average recurrence interval 83 years exceeded by one standard deviation 32 years

slip rate on the dead sea transform fault in northern araba valley jordan the araba valley lies between the southern tip of the dead sea and the gulf of aqaba this depression blanketed with alluvial and lacustrine deposits is cut along its entire length by the dead sea fault in many places the fault is well defined by scarps and evidence for left lateral strike slip faulting is abundant the slip rate on the fault can be constrained from dated geomorphic features displaced by the fault a large fan at the mouth of wadi dahal has been displaced by about 500 m since the bulk of the fanglomerates were deposited 77 140 kyr ago as dated from cosmogenic isotope analysis 10 be in chert of pebbles collected on the fan surface and from the age of transgressive lacustrine sediments capping the fan holocene alluvial surfaces are also clearly offset by correlation with similar surfaces along the dead sea lake margin we propose a chronology for their emplacement taken together our observations suggest an average slip rate over the late pleistocene of between 2 and 6 mm yr 1 with a preferred value of 4 mm yr 1 this slip rate is shown to be consistent with other constraints on the kinematics of the arabian plate assuming a rotation rate of about 0 396 myr 1 around a pole at 31 1 n 26 7 e relative to africa

active faulting in the dead sea rift abstract manifestations of late quaternary and holocene faulting were studied in a 500 km long segment of the dead sea transform rift most prominent are left slip faults whose characteristic physiographic features are recognizable along most of the studied segment where these faults bend or are stepped to the left rhomb shaped grabens or pull aparts are produced forming depressions in the reverse situation compressional features such as pressure ridges domes and folds form positive topographic features such structures are combined on a variety of scales ranging from a few hundred meters long to tens of kilometers normal faults sub parallel to the left slip faults produce a trough like valley along much of the dead sea transform but are most prominent along the margins of the large rhomb grabens e g the dead sea trough they apparently record a small component of transverse extension generally their motion is slow young slip did not occur along some segments during the last few 10 4 y elsewhere throws of 10 20 m at least occurred in this period the dead sea transform is seismically active the instrumental and historic records indicate a seismic slip rate of 0 15 0 35 cm y during the last 1000 1500 y while estimates of the average pliocene pleistocene rate are 0 7 1 0 cm y either much creep takes place or the slip rate varies over periods of a few 10 3 y

reconstruction of the glacial ice covers of greenland and the canadian arctic islands by three dimensional perfectly plastic ice sheet modelling a three dimensional perfectly plastic ice sheet model developed for determining the surface elevations and the flow pattern of an ice sheet with given bottom topography and ice margin positions is applied to the reconstruction of the glacial ice covers of greenland and the canadian arctic islands in the northern regions two different reconstructions have been performed with ice margins along the present 600 and 200 m sea depth contours respectively in central greenland the ice margin is considered to be at the outermost ice margin deposits on the coastal shelf to the west and at the present 200 m sea depth contour to the east the main conclusions to be drawn from the reconstructions are 1 the flow pattern of the glacial ice cover of greenland shows a great resemblance to the present one the central ice divide being displaced less than 50 km from its present position and being no more than 200 m higher than today 2 the main ice divide of the ice sheet covering the canadian arctic islands the innuitian ice sheet was located over the highlands of eastern ellesmere island with local domes positioned over the present ice caps indicating that even the deep ice of wisconsin age in these ice caps is of local origin this is also the case for the devon island ice cap 3 even in the not very likely case of a rather extensive glacial ice cover in north west greenland the ice flow pattern upstream of the camp century deep drill site would not have changed radically compared to the present flow pattern thus it is concluded that even advanced ice margins in late wisconsin time could at most have resulted in an elevation of the deposition site of the late wisconsin ice at camp century 600 m higher than at present the consequences of this conclusion are discussed

geometry and subsidence history of the dead sea basin a case for fluid induced mid crustal shear zone 1 pull apart basins are narrow zones of crustal extension bounded by strike slip faults that can serve as analogs to the early stages of crustal rifting we use seismic tomography 2 d ray tracing gravity modeling and subsidence analysis to study crustal extension of the dead sea basin dsb a large and long lived pull apart basin along the dead sea transform dst the basin gradually shallows southward for 50 km from the only significant transverse normal fault stratigraphic relationships there indicate basin elongation with time the basin is deepest 8 8 5 km and widest 15 km under the lisan about 40 km north of the transverse fault farther north basin depth is ambiguous but is 3 km deep immediately north of the lake the underlying pre basin sedimentary layer thickens gradually from 2 to 3 km under the southern edge of the dsb to 3 4 km under the northern end of the lake and 5 6 km farther north crystalline basement is 11 km deep under the deepest part of the basin the upper crust under the basin has lowerpwave velocity than in the surrounding regions which is interpreted to reflect elevated pore fluids there within data resolution the lower crust below 18 km and the moho are not affected by basin development the subsidence rate was several hundreds of m m y since the development of the dst 17 ma similar to other basins along the dst but subsidence rate has accelerated by an order of magnitude during the pleistocene which allowed the accumulation of 4 km of sediment we propose that the rapid subsidence and perhaps elongation of the dsb are due to the development of inter connected mid crustal ductile shear zones caused by alteration of feldspar to muscovite in the presence of pore fluids this alteration resulted in a significant strength decrease and viscous creep we propose a similar cause to the enigmatic rapid subsidence of the north sea at the onset the north atlantic mantle plume thus we propose that aqueous fluid flux into a slowly extending continental crust can cause rapid basin subsidence that may be erroneously interpreted as an increased rate of tectonic activity

active transform fault zone at the fringe of the dead sea basin the evolution of an asymmetric basin at the edge of a pull apart structure is studied using geophysical observations and mechanical modeling a new seismic analysis of the northern edge of the dead sea basin indicates recent subsidence folding and oblique faulting along the jericho strike slip fault a main segment of the dead sea transform fault the subvertical fault trace crosses the entire sedimentary sequence typically branching in the shallow subsurface the seismic analysis reveals the three dimensional structure of the area as an asymmetrical basin bordered on the east and on the west by long monoclinic folds the thickness of the sedimentary fill varies from 1 4 km near the present lake shores to a few hundreds of meters about 10 km northward the subsidence is partitioned between a vertical component of slip along the jericho fault and the simultaneously active monoclines bordering the basin we present a model and simulations that reconstruct the present basin structure in the uppermost part of the crust and demonstrates the generation of flexures along the basin margins without horizontal shortening we show that the basin asymmetry and the association of folds and fault can be explained as a long term ductile response of the sediments to local subsidence the asymmetry along the basin is a consequence of a later vertical displacement component on a pre existing strike slip fault our analysis points to ongoing northward propagation of the dead sea basin and provides an explanation for the structural asymmetry of the basin margins

multivariate analysis and quantitative paleoecology of benthic foraminifera in surface and late quaternary shelf sediments northern canada abstract benthic foraminifera in surface sediments from northeastern canada and the beaufort shelf were studied to determine the quantitative relationship between recent assemblage distributions and modern water depth temperature and salinity factor analysis shows that 7 factor assemblages account for 92 of the variance between samples multiple linear regression shows that different factors are significantly related to water depth august bottom water temperature or salinity multiple correlation coefficients for depth temperature and salinity are 0 94 0 72 and 0 92 respectively labrador fjords contain arenaceous faunas dominated by eithersaccammina atlantica andreophax fusiformis or byeggerella advena regression analysis shows that thesaccammina reophax factor is most strongly related to salinity theeggerella factor is related to depth and temperature a fauna dominated bytrochammina nana andbuliminella elegantissima is correlated with warm deep water in davis strait calcareous assemblages dominated byelphidium excavatum orcassidulina reniforme are found in arctic bays and shelf areas these factor assemblages are strongly related to temperature and depth cassidulina is also related to salinity anislandiella helenae fauna on the inner labrador shelf is strongly correlated with depth and salinity anonionellina labradorica fauna in deep shelf basins is closely related to salinity the multiple regression model for the sea bed data estimates water depth august bottom water temperature and salinity within confidence limits of 67 m 1 3 c and 1 0 paleoecological transfer functions were used to quantify environmental changes recorded by the foraminifera in two piston cores on a transect across the labrador shelf paleo depth estimates obtained from the core data produce relative sea level curves which are similar in shape to theoretical curves for this region paleo salinity and temperature estimates for offshore core 12 show that the change from a postglacialnonionellina fauna to a late glaciale excavatum fauna is accompanied by a decrease of about 2 in salinity and 4 c in temperature paleoecological estimates for fjord core 111 show that the change from a modernsaccammina reophax fauna to a mid holocenei helenae fauna corresponds to a salinity increase of 3 5 and temperature increase of 1 2 c

constraints on arabian plate motion and extensional history of the red sea analysis of the geologic and geophysical data from the western and northern margin of the arabian plate combined with data from the red sea gulf of aden leads to an interpretation of arabian plate motion that supports an episodic extensional history in the red sea and gulf of aden phase 1 extension began in medial to late eocene and was caused by the nw propagation of the reoriented central indian ridge spreading center it stretched and thinned continental crust along numerous wrench and normal faults that reactivated preexisting structures first phase extension stopped when the arabian plate terminally sutured to eurasia in the medial miocene and halted northward movement of arabia relative to africa the combined african arabian plates moved north more slowly constricting and thickening continental crust in the bitlis zagros sutures while the red sea remained technically quiescent and accumulated salt by the early pliocene continued northward movement was accommodated by lateral extrusion of large continental wedges north of the bitlis zagros sutures this allowed arabia to move northward faster than africa and reopen the red sea where phase 2 extension was expressed by seafloor spreading extension within the red sea gulf of aden rift system has been controlled by the interactions and effects of two factors 1 convergent processes between the north margin of the arabian plate and the eurasian plate to the north and 2 northwest propagation of extension associated with the medial eocene reorganization of the central indian spreading center

history of the greenland ice sheet paleoclimatic insights abstract paleoclimatic records show that the greenland ice sheet consistently has lost mass in response to warming and grown in response to cooling such changes have occurred even at times of slow or zero sea level change so changing sea level cannot have been the cause of at least some of the ice sheet changes in contrast there are no documented major ice sheet changes that occurred independent of temperature changes moreover snowfall has increased when the climate warmed but the ice sheet lost mass nonetheless increased accumulation in the ice sheet s center has not been sufficient to counteract increased melting and flow near the edges most documented forcings and ice sheet responses spanned periods of several thousand years but limited data also show rapid response to rapid forcings in particular regions near the ice margin have responded within decades however major changes of central regions of the ice sheet are thought to require centuries to millennia the paleoclimatic record does not yet strongly constrain how rapidly a major shrinkage or nearly complete loss of the ice sheet could occur the evidence suggests nearly total ice sheet loss may result from warming of more than a few degrees above mean 20th century values but this threshold is poorly defined perhaps as little as 2 c or more than 7 c paleoclimatic records are sufficiently sketchy that the ice sheet may have grown temporarily in response to warming or changes may have been induced by factors other than temperature without having been recorded

ice sheet extent and early deglacial history of the southwestern sector of the greenland ice sheet the offshore and coastal geomorphology of southwest greenland records evidence for the advance and decay of the greenland ice sheet during the last glacial maximum regional ice flow patterns in the vicinity of sisimiut show an enlarged ice sheet that extended southwestwards on to the shelf with an ice stream centred over holsteinsborg dyb high level periglacial terrain composed of blockfield and tors is dated to between 101 and 142 ka using 26al and 10be cosmogenic exposure ages these limit the maximum surface elevation of the last glacial maximum ice sheet in this part of southwest greenland to ca 750 810 m asl and demonstrate that terrain above this level has been ice free since mis 6 last glacial maximum ice thickness on the coast of ca 700 m implies that the ice sheet reached the mid to outer continental shelf edge to form the outer hellefisk moraines exposure dates record ice surface thinning from 21 0 to 9 8 ka with downwasting rates varying from 0 06 to 0 12 m yr 1 this reflects strong surface ablation associated with increased air temperatures running up to the bolling interstadial gis1e at ca 14 ka and later marine calving under high sea levels the relatively late retreat of the itilleq ice stream inland of the present coastline is similar to the pattern observed at jakobshavn isbrae located 250 km north in disko bugt which also retreated from the continental shelf after ca 10 ka we hypothesise that the ice streams of west greenland persisted on the inner shelf until the early holocene because of their considerable ice thickness and greater ice discharge compared with the adjacent ice sheet

pull apart basin formation and development in narrow transform zones with application to the dead sea basin contrary to other examples like death valley california and the sea of marmara turkey the dead sea type pull apart basins form within a narrow transform corridor between strike slip faults that are less than 10 km apart much smaller than the crustal thickness of 35 km in this paper we investigate the role of fault zone width versus thickness and rheology on the mechanics of pull apart basins through a series of laboratory experiments results show that pull apart basins that develop above a small step over i e smaller than the thickness of the brittle layer are narrow and elongated parallel to the overall motion this is enhanced by increased decoupling along a basal ductile layer the experiment with the highest degree of mechanical decoupling shows a striking resemblance to the dead sea basin dsb comparison with modeling results suggests that the dsb s flat basin floor is bordered over its full length by strike slip faults that control the basin geometry and temporal and spatial basin migration this is in strong contrast to death valley type pull apart basins that are highly oblique to the transform direction with transverse normal faults dominating over longitudinal strike slip faults results imply that lithosphere rheology and the ratio of basin width to crustal thickness are controlling factors in the mechanics of pull apart basin formation within transform corridors like the dead sea fault

crustal structure of the dead sea basin from local earthquake tomography summary new findings of the velocity structure of the crust across the dead sea basin are obtained by applying tomography based method to local earthquakes we use p wave traveltime of 614 earthquakes that occurred in the dead sea basin in 1983 2009 at all depths the dead sea basin is characterized by lower velocities relative to both the eastern and western sides of the basin there is significant seismic activity at a depth of about 20 km mainly in the centre and the northern part of the basin at shallow depths 15 km there is more seismic activity on the eastern side of the basin than on the western side and the northern basin is generally more active than the southern basin asymmetry is also observed in the faults that border the dead sea basin the arava fault on the eastern side with nearly vertical dip faulting appears to be a clear boundary at all depths down to about 20 km the depth extension of the jericho fault on the western side of the basin is definitely limited to less than 15 km at greater depths of 20 km or more the western side is only partially bounded by a fault the concentration of earthquakes in the central part of the basin at depths larger than 15 km suggests that the dead sea fault at those depths acts as one single fault that is located in or near the central axis of the basin the existence of a number of clusters of earthquakes that spread from shallow depths of a few kilometres up to a depth of about 22 km points to several defined faults that traverse the dead sea basin one such example is the aftershock sequence of the 2004 earthquake that occurred in the northern dead sea basin seismic activity near mt sodom is relatively low and occurs at shallow depths down to 10 km whereas at larger depths 15 km it ceases this implies that the whole structure is relatively shallow with no wide and deeper extension seismic activity near and within the lisan peninsula extends to somewhat larger depths 15 km and then it ceases the occurrence of earthquakes at large depths suggests that the upper and the lower crust are relatively cool as was also suggested by earlier studies pointing to the fact that the heat flow is significantly below the global average value

regional waveform inversion of 2004 february 11 and 2007 february 09 dead sea earthquakes summary two felt moderate size earthquakes with local magnitudes 5 2 on 2004 february 11 and 4 4 on 2007 february 09 occurred to the east of the dead sea and along the northern part of the arava araba fault arf respectively being well recorded by the national seismic networks operating on the dead sea region they offer a good opportunity to update the crustal model revealing the tectonic process and present day stress field on the dead sea region the observed group velocity dispersion of rayleigh and love waves picked from the broad band records for the 2004 and 2007 main shocks are used to update the jordan seismological observatory model which shows a good match between the observed and theoretical dispersion our updated model shows small traveltime residuals during our location process and yields a high variance reduction for our regional waveform inversion the earthquake hypocentre determined from the observed p and s wave traveltime data and regional waveform inversion indicate a source depth of 14 and 12 km for the 2004 and 2007 main shocks respectively focal mechanism obtained from both first motion polarities of local regional observations and moment tensor inversion of regional observations of 2004 earthquake reveal a mainly normal faulting with minor strike slip component along wnw ese fault whose orientation is nearly consistent with the transverse zarqa ma in fault however the focal mechanism of 2007 main shock shows left lateral strike slip faulting along a near vertical near nne ssw striking fault plane whose orientation is in good agreement with the surface expression of the observed northern arf the focal mechanism for a felt foreshock of 2007 earthquake indicates a similar left lateral strike slip fault with a slight normal component moment tensors estimated from regional waveforms indicate predominantly double couple mechanisms for the three studied events these results can be used to calibrate ground motions evaluate 3 d velocity models for simulation of large scenario earthquakes and seismic risk assessment along the dead sea fault

geology and evolution of the southern dead sea fault with emphasis on subsurface structure the dead sea fault is an active transform fault linking opening in the red sea with collision in the taurus zagros mountains motion is left lateral and estimated at approximately 5 7 mm year 1 the fault is seismically active and can be divided into two distinct structural segments this study focuses on the southern segment based mainly on the wealth of geophysical data owing to transtention caused by oblique slip and the overlapping of en echelon fault strands a series of pull apart basins were formed along the fault s length these basins are long and deep reaching in places more than 10 km deep they are characterized by extensional compressional and asymmetrical structures varying in size from large scale defining the general structure of the dead sea fault valley to small scale defining the internal structure this study examines the internal structure of these basins from south to north and summarizes the state of knowledge to date

evidence for general instability of past climate from a 250 kyr ice core record recent results1 2 from two ice cores drilled in central greenland have revealed large abrupt climate changes of at least regional extent during the late stages of the last glaciation suggesting that climate in the north atlantic region is able to reorganize itself rapidly perhaps even within a few decades here we present a detailed stable isotope record for the full length of the greenland ice core project summit ice core extending over the past 250 kyr according to a calculated timescale we find that climate instability was not confined to the last glaciation but appears also to have been marked during the last interglacial as explored more fully in a companion paper3 and during the previous saale holstein glacial cycle this is in contrast with the extreme stability of the holocene suggesting that recent climate stability may be the exception rather than the rule the last interglacial seems to have lasted longer than is implied by the deep sea specmap record4 in agreement with other land based observations5 6 we suggest that climate instability in the early part of the last interglacial may have delayed the melting of the saalean ice sheets in america and eurasia perhaps accounting for this discrepancy

bio and aminostratigraphy of some quaternary marine deposits in west greenland 14c dates and the geological setting of quaternary marine deposits from three sites in west greenland indicate a pre holocene age the mollusc faunas at the sites are distinctly different although

a tide generated internal waveform in the western approaches to the strait of gibraltar aircraft expendable bathythermograph radar infrared scanner and visual data collected in october 1982 1984 and 1985 as well as space shuttle photographs indicate that an internal waveform depending on flow conditions either an internal hydraulic jump or a lee wave is a semipermanent feature over the camarinal sill in the western approaches to the strait of gibraltar comparison of these data with both historic and recent current meter mooring data indicates that the waveform generated at the interface between the atlantic and mediterranean waters undergoes periodic changes wrought by interaction of the tidal current and the flow of the atlantic and mediterranean waters we believe that the waveform is a major mixing mechanism between the two water masses

age dating and the orbital theory of the ice ages development of a high resolution 0 to 300 000 year chronostratigraphy using the concept of orbital tuning a continuous high resolution deep sea chronostratigraphy has been developed spanning the last 300 000 yr the chronology is developed using a stacked oxygen isotope stratigraphy and four different orbital tuning approaches each of which is based upon a different assumption concerning the response of the orbital signal recorded in the data each approach yields a separate chronology the error measured by the standard deviation about the average of these four results which represents the best chronology has an average magnitude of only 2500 yr this small value indicates that the chronology produced is insensitive to the specific orbital tuning technique used excellent convergence between chronologies developed using each of five different paleoclimatological indicators from a single core is also obtained the resultant chronology is also insensitive to the specific indicator used the error associated with each tuning approach is estimated independently and propagated through to the average result the resulting error estimate is independent of that associated with the degree of convergence and has an average magnitude of 3500 yr in excellent agreement with the 2500 yr estimate transfer of the final chronology to the stacked record leads to an estimated error of 1500 yr thus the final chronology has an average error of 5000 yr