insolation values for the climate of the last 10 million years new values for the astronomical parameters of the earth s orbit and rotation eccentricity obliquity and precession are proposed for paleoclimatic research related to the late miocene the pliocene and the quaternary they have been obtained from a numerical solution of the lagrangian system of the planetary point masses and from an analytical solution of the poisson equations of the earth moon system the analytical expansion allows the direct determination of the main frequencies with their phase and amplitude numerical and analytical comparisons with the former astronomical solution ber78 are performed so that the accuracy and the interval of time over which the new solution is valid can be estimated the corresponding insolation values have also been computed this analysis leads to the conclusion that the new values are expected to be reliable over the last 5 ma in the time domain and at least over the last 10 ma in the frequency domain

sea rain lake relation in the last glacial east mediterranean revealed by δ18o δ13c in lake lisan aragonites we investigated the sea rain lake relation during the last glacial holocene in the east med iterranean region by comparing the 18 o and 13 c records of authigenic aragonite deposited in lake lisan the dead sea mediterranean foraminifera and speleothems the lisan formation data display long and short term variations of 18 o representing steady state conditions of the lake e g 5 6 0 5 and 4 5 1 in the upper and lower members of the lisan formation respectively and short term excursions reflecting large floods and droughts the long term steady state 18 o values of the lisan aragonites show similarity to the corresponding time equivalent records of the eastern mediterranean foraminifera and judea mountain speleothems the last glacial deposits are in all of them 2 3 heavier than the holocene ones we interpret this similarity as reflecting the significance of the source effect on the long term behavior of isotopic reservoirs speleothem 18 o is strongly influenced by the marine reservoir that contributes its vapor to rain formation the lake 18 o is dominated by the composition of the inflowing water short term variations in the isotopic composition of rainfall are dominated by the amount effect and the temperature and those of the lake s upper water mass by the lake s water balance 13 c values are more variable than 18 o in the same lisan sequences e g 13 c in the lower member is 1 0 1 7 whereas 18 o is 4 6 0 7 and are 1 to 1 5 higher in the upper member than in the lower and middle members of the lisan formation these variations reflect significant increase in primary productivity of the lake and algal bloom activity it appears that the hypersaline saline lakes were not as dead as the dead sea is and that algal activity had an important impact upon the geochemistry of lake lisan the 18 o data combined with independent geochemical and limnologic information e g level fluctuations indicate that lisan time was characterized by high precipitation high lake stands high atmospheric humidity whereas the holocene dead sea shows the opposite behavior this paleoclimatic reconstruction is consistent with independent evidence for significantly wetter conditions in the east mediterranean region during the last glacial period copyright 2005 elsevier ltd

evolution geochimique superficielle naissante des anorthosites cas du profil de château richer quebec canada the initial stages of the superficial geochemical weathering of anorthosites have been investigated in a deposit at ch teau richer quebec the parent rock consists almost exclusively of andesine and is weathered to a thickness of about 120 cm a till overburden indicates that the profile was truncated by the wisconsinian ice the rock is not extensively disintegrated but the chemical weathering is rather intense the parker diagram shows a strong decrease of the weathering index from the parent rock to the weathering zone while this is not the case for other crystalline rocks in the area it may be accounted for by the fragility of the plagioclase the 2 m fraction which amounts to 2 of the soil presents an evolution that is influenced by the site especially the drainage conditions at the base of the profile drainage is poor and 2 1 minerals smectite and vermiculite are present in addition to 40 kaolinite the 1 1 mineral increases to 60 near the contact with the till while the amount of 2

travertines in the northern hula valley israel this study describes the field and petrographic relationships of a widespread deposit of pleistocene travertines in the northern hula valley northern israel the travertines interfinger with conglomerate deposits and basaltic lava flows field relationships and radiometric dating indicate that the travertines accumulated intermittently over the past million years and their formation virtually stopped 25 000 years ago the travertines are characteristically highly porous some of the pores as well as some spar filled voids preserve the shapes of stalks and leaves the abundance of plant material suggests that photosynthesis rather than bacterial or abiogenic processes was the main mechanism which induced carbonate precipitation the reasons for travertine accumulation in the past and for the cessation of its formation today are ascribed to differences in the palaeogeographic setting in the past water flow is viewed as having been mostly sluggish and a widespread and shallow sheet of water was formed the lush vegetation combined with the relatively long residence time of the water in the area led to increased efficiency of the calcium carbonate precipitation today by contrast water flows rapidly in gorges precipitating only a small fraction of its load of dissolved calcium carbonate the conjectured change in hydrological conditions is ascribed to rejuvenation of faulting activity in the late quaternary

strontium and oxygen isotopic variations in mesozoic and tertiary plutons of central idaho regional variations in initial 87sr 86sr ratios r i of mesozoic plutons in central idaho locate the edge of precambrian continental crust at the boundary between the late paleozoic mesozoic accreted terranes and precambrian sialic crust in western idaho the r i values increase abruptly but continuously from less than 0 704 in the accreted terranes to greater than 0 708 across a narrow 5 to 15 km zone characterized by elongate lens shaped highly deformed plutons and schistose metasedimentary and metavolcanic units the chemical and petrologic character of the plutons changes concomitantly from ocean arc type diorite tonalite trondhjemite units to a weakly peraluminous calcic to calcalkalic tonalite granodiorite granite suite the idaho batholith plutons in both suites yield late cretaceous ages but permian through early cretaceous bodies are confined to the accreted terranes and early tertiary intrusions are restricted to areas underlain by precambrian crust the two major terranes were juxtaposed between 75 and 130 m y ago probably between 80 and 95 m y oxygen and strontium isotopic ratios and rb and sr concentrations of the plutonic rocks document a significant upper crustal contribution to the magmas that intrude precambrian crust magmas intruding the arc terranes were derived from the upper mantle subducted oceanic lithosphere and may have been modified by anatexis of earlier island arc volcanic and sedimentary units plutons near the edge of precambrian sialic crust represent simple mixtures of the precambrian wall rocks with melts derived from the upper mantle or subducted oceanic lithosphere with r i of 0 7035 rb sr varies linearly with r i producing pseudoisochrons with apparent ages close to the age of the wall rocks measured 18o values of the wall rocks are less than those required for the assimilated end member by sr o covariation in the plutons however indicating that wall rock 18o was reduced significantly by exchange with circulating fluids metasedimentary rocks of the belt supergroup are similarly affected near the batholith documenting a systematic depletion in 18o as much as 50 km from the margin of the batholith plutons of the bitterroot lobe of the idaho batholith are remote from the accreted terranes and represent mixtures of precambrian wall rocks with melts dominated by continental lower crust r i 0 708 rather than mantle pseudoisochrons resulting from these data are actually mixing lines that yield apparent ages less than the true age of the wall rocks and meaningless ri assimilation fractional crystallization models permit only insignificant amounts of crystal fractionation during anatexis and mixing for the majority of plutons of the region

a late pleistocene long pollen record from lake urmia nw iran abstract a palynological study based on two 100 m long cores from lake urmia in northwestern iran provides a vegetation record spanning 200 ka the longest pollen record for the continental interior of the near east during both penultimate and last glaciations a steppe of artemisia and poaceae dominated the upland vegetation with a high proportion of chenopodiaceae in both upland and lowland saline ecosystems while juniperus and deciduous quercus trees were extremely rare and restricted to some refugia hippophae rhamnoides constituted an important phanerophyte particularly during the late last glacial period a pronounced expansion in ephedra shrub steppe occurred at the end of the penultimate late glacial period but was followed by extreme aridity that favoured an artemisia steppe very high lake levels registered by both pollen and sedimentary markers occurred during the middle of the last glaciation and late part of the penultimate glaciation the late glacial to early holocene transition is represented by a succession of hippophae ephedra betula pistacia and finally juniperus and quercus the last interglacial period eemian slightly warmer and moister than the holocene was followed by two interstadial phases similar in pattern to those recorded in the marine isotope record and southern european pollen sequences

on the shape of paleomagnetic data sets a quick and easy method to analyze the shape of paleomagnetic data sets is described and illustrated the elongation e of a set of directions of virtual geomagnetic poles vgp is defined as e k2 k3 where k2 and k3 are the second and third eigenvalues of the bingham distribution it is shown that e 3 or so indicates that the distribution is significantly elongate although the size of the sample and the paleolatitude both affect this conclusion because the azimuth of k2 gives the direction of elongation it can be used to help determine why a particular distribution is elongate it is shown that for most units from the craton both directions and vgp are nearly circular except for units magnetized at very low latitudes in general poles are more circular than directions some units formed in plate margin locations also are circular but many are highly elongate many units from the western cordillera of north america have highly elongate distributions that are compatible with origin within a shear zone others are obviously underformed internally units formed during extension are less commonly elongate but some show the probably effects of normal faulting it is hoped that shape analysis will be part of any complete paleomagnetic study in the future

an absolute paleotemperature record from 10 to 6 ka inferred from fluid inclusion d h ratios of a stalagmite from vancouver island british columbia canada abstract by using continuous helium flow during the crushing of calcite speleothem samples we are able to recover liberated inclusion waters without isotopic fractionation a paleotemperature record for the jacklah jill cave locality vancouver island bc was obtained from a 30 cm tall stalagmite that grew 10 3 6 3 ka ago using 18 o values of the crushed calcite and of the inclusion water as inferred from its d it is found that the locality experienced mean annual temperature variations up to 11 c over a 4 ka period in the early holocene at the beginning of the period local temperature quickly increased from a minimum of 1 c to around 10 c but this early climate optimum about 3 c warmer than today only lasted for 1200 years about 8 6 ka ago temperature had declined to 7 c approximately the same as the modern cave temperature since then the study area has experienced only minor temperature fluctuations but there was a brief fall to 4 c at around 7 ka ago which might be caused by a short lived expansion of local alpine glaciers the long term t dependence of d was 1 47 c identical to the value in modern precipitation

timing and climatic impact of greenland interstadials recorded in stalagmites from northern turkey a 50 kyr long exceptionally well dated and highly resolved stalagmite oxygen 18o and carbon 13c isotope record from sofular cave in northwestern turkey helps to further improve the dating of greenland interstadials gi 1 and 3 12 timing of most gi in the sofular record is consistent within 10 to 300 years with the iconic hulu cave record larger divergences 500 years between sofular and hulu are only observed for gi 4 and 7 the sofular record differs from the most recent ngrip chronology by up to several centuries whereas age offsets do not increase systematically with depth the sofular record also reveals a rapid and sensitive climate and ecosystem response in the eastern mediterranean to gi whereas a phase lag of 100 years between climate and full ecosystem response is evident finally results of spectral analyses of the sofular isotope records do not support a 1 470 year pacing of gi

d h ratios of fluid inclusions of soreq cave israel speleothems as a guide to the eastern mediterranean meteoric line relationships in the last 120 ky abstract d h studies of fluid inclusions of speleothems of the soreq cave israel are made using the method of vacuum thermal extraction d h measurements of present day carbonate pool margins and waters show that the value of the vacuum thermal extraction fractionation ex d extracted water d cave water is 30 0 1 4 for the soreq cave deposits d h analyses of fluid inclusions of two fossil speleothems formed during periods equivalent to glacial times suggest that their isotopic compositions follow the global meteoric water line mwl d 18 o relationship compared to present day waters which follow the mediterranean meteoric water line mmwl trend two samples from interglacial periods show isotopic trends between these lines these differences are presumed to reflect cooler less evaporative conditions in the eastern mediterranean sea during glacial times

the role of material anisotropy in the neotectonic extension of the western idaho shear zone mccall idaho basin and range normal faulting in west central idaho reactivates preexisting cretaceous structures resulting in a series of normal fault bound basins the most intense extensional deformation is concentrated in the late cretaceous western idaho shear zone resulting in the development of the long valley basin the area affected by the western idaho shear zone displays two orientations of steep faults one set of normal faults strikes north south and is parallel to fabrics within the western idaho shear zone the other set strikes east west and accommodates components of both normal and strike slip movement areas within the idaho batholith that do not have strong cretaceous fabrics i e outside of the western idaho shear zone are characterized by a strong preferred north northeast orientation of faults from this preferred orientation we infer that the maximum infinitesimal stretch is oriented at 110 290 in this part of the idaho batholith gravity inversion indicates that the north end of long valley is an asymmetric basin about one kilometer deep with the largest basin bounding normal fault on the west side of the long valley paleomagnetic analysis of the columbia river basalts indicates that the north south elongate fault blocks within the western idaho shear zone have not rotated one block located just to the west of the western idaho shear zone may have rotated counterclockwise the lack of rotation of north south oriented fault blocks in combination with the fault orientations of the idaho batholith indicate that the regional neotectonic deformation within and east of the western idaho shear zone is characterized by dextral transtension with a divergence vector oriented 130 310 the extensional reactivation of the western idaho shear zone demonstrates the effect of material anisotropy at local and regional scales on a local scale the mylonitic foliation of the western idaho shear zone is reactivated as normal faults even though the regional flow field is oblique to the foliation on a regional scale the possible counterclockwise fault block rotation recorded west of the western idaho shear zone is inconsistent with dextral transtension suggesting that extensional deformation has reactivated the western edge of the arc craton boundary as a kinematic domain boundary we conclude that the preservation of initial features in vertical shear zones and or plate boundaries is unlikely due the tendency for well developed subvertical fabrics to reactivate particularly in extension

pleistocene water intrusions from the mediterranean and caspian seas into the black sea the hydrological balance of the black sea is governed by riverine input and by the exchange with the mediterranean sea a speleothem record from a cave in northern turkey that tracks the isotopic signature of black sea surface water suggests an open connection to the mediterranean sea in at least twelve periods in the past 670 000 years

modelling precipitation streamflow processes in karst basin the case of the jordan river sources israel summary a system approach daily precipitation streamflow model was developed for both the base and the surface flow components of large scale karst basins long term streamflow data were separated to baseflow and surface flow using the recursive digital filter method which provides time series for model calibration the hydrological model for karst environment hymke includes attributes to large scale preferential flow that recharge the groundwater and solve the problem of uncorrelated baseflow and surface flow in a karst environment hymke was applied simultaneously to the three major tributaries of the upper catchment of the jordan river which originate in the karstic region of the hermon mountain northern israel it was verified by comparing the calculated surface flow and baseflow with the daily time series of the baseflow separation procedure and demonstrated good agreement of both the surface r2 0 6 and baseflow r2 0 77 components of each stream

use of anisotropy to determine the origin of characteristic remanence in the siwalik red beds of northern pakistan it is often difficult or impossible to determine the origin of the characteristic remanent magnetization of red beds from the bulk remanence alone however anisotropy of remanence or susceptibility is strongly controlled by the statistical alignment of hematite grains this in turn may reflect the development of the magnetic fabric of the sediment over time so the shape of the anisotropy ellipsoid may provide clues to the origin of remanence in this work we make a study of the anisotropy of magnetic susceptibility ams in siwalik red beds of miocene age from northern pakistan comparison of the results with detailed petrographic studies and other information suggests that advanced soil development leads to the destruction of primary fabrics and often with it a coherent magnetization furthermore it should be possible to use ams fabric information to quantify the degree of pedogenesis in these miocene soils we attempted to determine the anisotropy of isothermal remanence air but found ams to be the technique of choice because of apparent changes in coercivity during air experiments we interpret the air data as resulting from metastable domains in hematite grains which change domain state during the air experiment

mountain building strike parallel motion and mantle anisotropy abstract geophysical and geological evidence indicates that tectonic movements parallel to the strike of orogenic belts and suture zones are the most important mode of displacement during continental collision and oblique subduction several hundred to a few thousand kilometers of displacement may have occurred this way resulting in a pervasive ductile deformation of the lithosphere consequently both crustal and mantle fabrics may reflect these movements and their study using both geological and geophysical methods could supply important clues to lithosphere behavior during mountain building on the basis of kinematic analysis of ductilely deformed crustal rocks in zones of movement a variety of tectonic models have been proposed which differ in 1 1 the timing of strike parallel motions early before or during continental accretion or late after accretion was completed 2 2 the geometric pattern of strike parallel displacement zones low angle or high angle and 3 3 the location of orogen parallel movement zones in outboard terranes on the subducting plate along the suture zone or within the continental hangingwall large scale displacements parallel to mountain belts also suggest that they occurred along lithospheric faults rooted in the upper mantle although few studies have been carried out from this view point thermal structural and petrological data support the conclusion that lithospheric faults involving the upper mantle may be discriminated from crustal faults rooted in some crustal decoupling zone where available data on mantle flow beneath orogenic belts are in agreement with mountain parallel displacements inferred from crustal studies this has an important bearing on the seismic anisotropy pattern which can be predicted in the lithospheric mantle below mountain belts the fast velocity direction which is parallel to the flow direction should therefore be recorded parallel to the strike of the belt

the relationship between strain rates crustal thickening palaeomagnetism finite strain and fault movements within a deforming zone the deformation of continental lithosphere generally does not occur on a single fault but is distributed over a zone up to a few hundred kilometers wide if the deformation rate is constant throughout the zone and if the velocity is continuous everywhere and does not change with time the deformation gradient tensor can be obtained analytically this tensor directly determines the amount of crustal thickening and is related in a complicated manner to the finite strain tensor the declination of remnant magnetization measured within the zone can also be rotated by the deformation because palaeomagnetic measurements are generally made on rigid blocks which have not been deformed there is no simple relationship between such rotations and the finite strain expressions for all these quantities are obtained in terms of the velocity gradients which are taken to be constant the history of western north america is used to illustrate the relationship between the present deformation by strike slip and thrust motions the rotations of the remnant magnetization vectors and the shape of accreted terranes at the surface distributed deformation is taken up by motion on faults which separate the zone into blocks the displacement rate on the faults their strike and the finite rotations of the blocks are all controlled by the velocity gradients analytic expressions relating these quantities are obtained a deforming zone containing normal faults which crosses central greece takes up both strike slip and extension and illustrates the relationship between the structures within and the motion across the zone a similar but more complicated zone in northeastern iran involves both strike slip and shortening

mg sr and sr isotope geochemistry of a belgian holocene speleothem implications for paleoclimate reconstructions in this study variations in mg ca sr ca and 87sr 86sr ratios in a holocene belgian speleothem cave secondary carbonate deposit are interpreted in terms of changes in water residence time and changes in weathering processes possibly induced by changes in west european climate a stalagmite from the pere noel cave belgium was dated with the tims u th method and was deposited between 13 and 2 ka bp the 1000 mg ca ratio varies between 4 9 and 26 and displays short term changes but no significant long term trend the 1000 sr ca ratio varies between 0 09 and 0 31 and displays both short term changes and a long term decreasing trend from 12 9 to 3 5 ka in parallel the sr isotopic composition of the speleothem decreases from 0 7090 at 12 9 ka to 0 7088 at 3 5 ka the sr isotope ratio is higher than expected from the overlying limestone 87sr 86sr 0 7081 which implies an external source of radiogenic sr most probably from a silicate phase short term and long term changes in mg ca sr ca as well as long term changes of 87sr 86sr ratios can be explained by changes in the dissolution and precipitation processes of the host limestone these processes are controlled by changes in water residence times linked to changes in the water excess precipitation minus evapo transpiration c 2000 elsevier science b v all rights reserved

controlling factors on a paleo lake oxygen isotope record yammouneh lebanon since the last glacial maximum abstract late quaternary paleoclimatic changes in the levant are difficult to extract from carbonate oxygen isotope records partly because the factors controlling the terrestrial 18 o signals are not fully understood in this region characterized by sharp climatic gradients here we address this purpose by presenting the first 14 c dated isotope record from the northern levant the record is based on oxygen isotopes from ostracod shells from lacustrine palustrine deposits accumulated in a small karstic hydrologically open basin yammouneh located on the eastern flank of mount lebanon we have first constructed a composite isotopic record obtained from three different ostracod taxa this yields an oxygen isotope record of ostracods ost related to the most widespread species ilyocypris inermis and converted to 18 o values coeval with calcite precipitated in equilibrium c with the lake water l as with other records from the mediterranean region the yammouneh profile shows maximum and minimum c values during the lgm and the early holocene respectively and a slight late holocene increase in order to discuss the potential causes of the observed 18 o values fluctuations e g changes in the isotopic composition of the moisture source temperature precipitation minus evaporation p e balance or atmospheric circulation we tentatively reconstruct the lake water isotope composition by correcting the c values for lake water temperature using regional paleotemperature estimates inferred l values were then corrected for the isotopic composition of the eastern mediterranean sea surface water the moisture source derived from planktonic foraminifera 18 o values corrected for alkenone based sea surface temperature our study suggests that holocene l fluctuations are primarily linked to changes in the sea surface water composition source effect amplified by enhanced inland rainfall during the early holocene during the lgm low l values at yammouneh are likely due to the ground temperature effect on the rainfall isotope composition possibly associated with a steeper altitudinal thermal gradient inland and with changes in air mass trajectories over the mediterranean sea

high resolution temporal record of holocene ground water chemistry tracing links between climate and hydrology strontium isotope analysis of precisely dated calcite growth layers in holocene speleothems from barbados west indies reveals high resolution temporal variations in ground water composition and may provide a new approach to documenting the links between climate variability andfluctuations in the hydrologic cycle such as recharge rates andflow paths the speleothems grew in a cave that developed in a fresh water aquifer in upliftedpleistocenereeflimestones threeperiodsofground watersrisotopeevolutionare observed 87 sr 86 srvaluesdecreasedfrom6to4ka increasedfrom4to1ka anddecreased again after 1 ka the sr isotope oscillations appear to record periodic variations in the relative sr fluxes to ground water from exchangeable soil sites vs carbonate mineral reactions asreflectedin 87 sr 86 srvaluesofmodernbarbadosgroundwaters ahydrologic model that explains changes in ground waterflow routes in karst aquifers as a function of amountofrainfallrechargecanaccountforthespeleothemsrisotoperecord independent holoceneclimaterecordsthatindicateamajorperiodofaridityataround1 3 1 1kainthe american tropics correspond with periodic variations in rainfall on barbados that are predicted by this hydrologic model

climatic conditions during marine oxygen isotope stage 6 in the eastern mediterranean region from the isotopic composition of speleothems of soreq cave israel at several times during marine oxygen isotope stage 6 the eastern mediterranean region was influenced by two extreme climatic systems the large ice sheet over northern europe and the wet tropics associated with african monsoons during this interval two major climatic events occurred in the region the sapropel s6 layer formed ca 176 ka in the eastern mediterranean basin owing to the increase in the african monsoon and another event although not large enough to form sapropel occurred ca 151 ka the isotopic composition of soreq cave speleothems seems to record these events as very low 18 o 13 c values dated as ca 178 and 152 ka the very low 18 o 13 c values of 6 and 11 to 12 respectively are typical of interglacial intervals but here they were recorded during a glacial interval such low peaks indicate that in this part of the eastern mediterranean region i e israel the rainfall amount increased dramatically moreover the isotopic record of the speleothems also shows that during the entire stage 6 although the climate was as cold as much of the last glacial the conditions were never as dry

87 sr 86 sr and 18 o 16 o isotopic systematics and geochemistry of granitoid plutons across a steeply dipping boundary between contrasting lithospheric blocks in western idaho a spatially abrupt geochemical boundary is preserved within four plutonic complexes along the western margin of the cretaceous idaho batholith near mccall idaho these intrusives ranging in composition from tonalite to granite were emplaced across a regional boundary between accreted oceanic arc terranes and the continental margin and their isotopic major element and trace element geochemistry provide detailed information about this change in crustal characteristics at depth indicating that the boundary is nearly vertical and extends deep into the lithosphere the hazard creek complex emplaced west of the transition in wall rock lithology has initial 87sr 86sr ri less than 0 7045 and 18o greater than 7 5 indicating little or no continental crust in its source region however elevated 18o requires some incorporation of rocks formed or altered at the earth s surface a large shift in ri and 18o is observed across the 5 8 km wide little goose creek complex which was emplaced across the wall rock boundary this is interpreted as mixing between 1 a basaltic or andesitic magma with low k2o and high na2o al2o3 and sr similar to that forming the hazard creek complex and 2 materials similar to precambrian sedimentary sedimentary rocks with low sr high 18o 15 and high ri 0 83 at 100 ma the payette river complex emplaced east of the wall rock boundary exhibits at least one additional component with low 18o 6 moderate ri 0 708 and mafic composition this component is inferred to be old basaltic material in the lower crust or upper mantle similar to that inferred to be a minor part of the peninsular ranges batholith in se california silver et al 1979 hill et al 1986 the easternmost complex in the idaho transect is made up of granites that may contain a component of granitic cratonal basement the entire west to east geochemical transition from oceanic arc magmas to cratonal magmas takes place over a lateral distance of less than 20 km although the zone of transitional protolith dominated by metasedimentary rocks is unusually narrow and may have been in part tectonically removed the striking geochemical similarities between this traverse and several other transects across much broader areas of nevada and california suggest that the craton itself was not rifted apart but that juxtaposition of the accreted oceanic arc terranes occurred along the preexisting craton margin the data confirm that the isotopic geochemistry of granitoid plutons can be used as a probe of deep lithospheric character and that major lateral variations in the lithosphere on the order of one to two kilometers in width can be recognized in favorable circumstances

oblique plate motion and continental tectonics three dimensional deformation is necessarily associated with oblique plate convergence and commonly results in partitioning of deformation between contractional and transcurrent components along plate margins kinematic models of strike slip partitioning for transpression and transtension allow the exact relation among three critical parameters plate motion instantaneous strain axes and degree of strike slip partitioning to be calculated application to two end member tectonic environments characterized by a low south island new zealand and high central california degree of strike slip partitioning demonstrates a remarkable consistency among the three parameters suggesting that strike slip partitioned transpression is a valid model for deformation in these regions the extreme degree of strike slip partitioning in wrench dominated systems such as central california is tentatively associated with a fundamental misorientation of finite and instantaneous strain axes

constraints on hydrological and paleotemperature variations in the eastern mediterranean region in the last 140 ka given by the δd values of speleothem fluid inclusions abstract speleothem fluid inclusions potentially provide vital data on the paleohydrological conditions in glacial and interglacial periods we show here that d analyses of fluid inclusions from speleothems in three caves in the eastern mediterranean region israel provide a basis for understanding hydrological and temperature variations in the last 140 ka using measured d fluid inclusion values and temperature ranges constrained by the present day mediterranean meteoric water line mmwl and the global mwl we show a strong compatibility between the land and marine temperature records with the highest land temperatures occurring at 120 130 ka 17 22 c and the present 18 c and the lowest temperatures during the lgm about 10 c lower than present interglacial waters are constrained to follow the mmwl and most glacial waters also plot close to the mmwl with a slight shift towards the mwl however during two remarkable brief periods at the termination of the lgm the waters plot on the mwl suggesting that both sharp cooling and an increase in relative humidity above the em sea reduced d excess values to those of the global system

a 250 ka sedimentary record from a small karstic lake in the northern levant yammouneh lebanon paleoclimatic implications the levant influenced by both the mediterranean sea and the saharan arabian deserts is a key region for understanding climatic changes in response to glacial interglacial boundary conditions that have greatly affected regional hydrology here we present the first long term paleoenvironmental record from the northern levant presently much wetter than the southern levant our record derives from the multi proxy study of a sediment core 36 m long retrieved from the small intra mountainous tectonic basin of yammouneh lebanon which is mainly supplied by karstic springs sediments consist of a thick accumulation of brownish to greenish clayey silts interrupted by intervals of whitish marls composed of caco3 rich material the core chronology is based on radiometric dating 14c and u th and paleomagnetic techniques the sedimentary sequence spans approximately the last two glacial interglacial cycles 250 ka carbonate content is relatively high throughout the profile due to a perennial input of detrital calcite from the watershed but varies significantly the marls are mostly composed of authigenic and biogenic calcite and reflect lacustrine environments with high carbonate productivity during peaks of interglacial periods their occurrence suggests low physical erosion of the basin slopes which were covered by arboreal vegetation and intense karstic water circulation under warm and relatively wet conditions in agreement with pollen data the clayey silts are dominated by quartz and clay minerals and a few amounts of k feldspars and dolomite they are characterized by high concentration in magnetic particles and high relative concentrations of si al k and fe considered as strictly of detrital origin due to the carbonated nature of the watershed quartz and k feldspars are attributed to eolian origin from a distal source the clayey silt intervals generally suggest palustrine conditions with abrupt flows responsible for runoff derived material or subaerial environments and low local water availability in particular during the last glacial maximum high si al and k al ratios during interglacials are attributed to relatively high eolian dust contribution due to the decrease of local detrital inputs our study reveals significant differences between yammouneh and lake records from the dead sea basin southern levant the latter showing high low levels during glacial interglacial periods these hydrological differences might reflect either changes in the north south ns rainfall gradient in response to the development of the northern ice sheet and the southward migration of the westerly belt or local factors i e a decrease in efficient precipitation and water availability at yammouneh during the coldest glacial periods e g the last glacial maximum due to water storage by ice caps on the mount lebanon range and frozen soils in the yammouneh basin

age and paleoclimatic implications of the bet shean travertines abstract from 41 000 to over 22 000 yr b p a massive and areally extensive spring travertine was deposited in the bet shean valley israel this travertine is coeval with the ami az member of the lisan formation which represents a high lake stand the travertine deposition is contemporaneous with a more active hydrologic regime associated with wetter conditions in the arid zones of the southern levant adjacent to southern israel these wetter conditions facilitated formation of a widespread spring tufa and also enhanced the water levels of lake lisan

the eastern mediterranean paleoclimate as a reflection of regional events soreq cave israel the climate of the eastern mediterranean region of the last 60 ky was determined by a high resolution study of the oxygen and carbon isotopic composition 1500 measurement pairs of speleothems from the soreq cave israel with chronology provided by 53 precise 230 th 234 u tims ages the high precision of the speleothem tims ages permits us to determine the timing of regional climatic events in the eastern mediterranean region and to see if they correlate with global events during the period from 60 to 17 ky the 18 o and 13 c values were generally 2 2 5 higher than during the period from 17 ky to present this is consistent with the climatic transition from glacial to interglacial within the 60 to 17 ky period the soreq cave stable isotope profile includes four cold peaks at 46 35 25 and 19 ky and 2 warm peaks at 54 and 36 ky in addition the period 17 ky has two more cold peaks at 16 5 and from 13 2 to 11 4 ky the ages of four of the six cold peaks correlate well with the ages of three heinrich events h1 h2 h5 and with the age of the younger dryas however the other two heinrich events are not reflected in the soreq cave record several other isotope peaks which appear during the last 7 ky are contemporaneous with regional climatic events in the middle east and north africa in addition to the drop in 18 o and 13 c observed between the last glacial and the holocene sharp simultaneous drops in 234 u 238 u 0 ratios sr concentrations and in 87 sr 86 sr are also observed suggesting that the latter are climate related these variations are interpreted in terms of major changes in the temperature the mean annual rainfall and its isotopic composition the isotopic composition of the mediterranean vapor source the soil moisture conditions and in the mixing proportions of sources with different 87 sr 86 sr ratios sea spray dust particles and dolomitic host rock

quaternary reactivation of the kern canyon fault system southern sierra nevada california the kern canyon fault the longest fault in the southern sierra nevada is an active structure and has been reactivated at discrete times over the past 100 m y in response to changing lithospheric stresses after initiation as a cretaceous transpressional structure the kern canyon fault transitioned into a dextral strike slip shear zone that remained active as it was exhumed into the brittle regime during regional late cretaceous uplift of the sierra nevada batholith the kern canyon fault was reactivated during miocene regional extension as part of a transfer zone between two differentially extending domains in the southern sierra nevada subsequent normal displacement along the fault began in pliocene time new evidence for fault activity which continued into late quaternary time includes its current geomorphic expression as a series of meters high west side up scarps that crop out discontinuously along the fault s 130 km length relocated focal mechanisms of modern earthquakes confirm ongoing normal faulting and geodetic measure ments suggest that the sierra nevada is uplifting relative to the adjacent valleys this evidence for recent activity overturns a long held view that the kern canyon fault has been in active for more than 3 5 m y its reactivation indicates that deformation repeatedly localized along a pre existing crustal weakness a cretaceous shear zone we propose that a system of inter related normal faults including the kern canyon fault is responding to mantle lithosphere removal beneath the southern sierra nevada region the location of the active kern canyon fault within the sierra nevada great valley microplate indicates that deformation is occurring within the microplate

last glacial warm events on mount hermon the southern extension of the alpine karst range of the east mediterranean abstract this study focuses on warm last glacial episodes in the southernmost extension of the alpine karst range of the eastern mediterranean levant region through the study speleothems in mizpe shelagim cave located in mt hermon the alpine karst range extends from turkey through syria and lebanon reaching its southern limit in mt hermon at an elevation of more than 2000 m under present day conditions southern mt hermon receives 1000 2000 mm precipitation mostly as snow that originates in the eastern mediterranean sea speleothems deposition in this high altitude region was continuous during interglacials but during the last glacial growth only occurred when average annual temperatures exceeded 3 c as inferred from the study of speleothem fluid inclusions warming episodes occurred at 65 ka 56 ka 54 5 ka 52 5 51 ka 49 ka 42 ka and 36 ka and are coincident with maximum insolation at 65 n the main depositional period from 56 ka to 51 ka coincides with dansgaard oeschger interstadial 15 and 14 and warming in the northeastern basin of the mediterranean sea warming in the southern alpine karst range of the eastern mediterranean was manifested by vegetation development together with significant snow melting that resulted in the drainage of large amount of water to the dead sea rift valley

a note on fault reactivation reactivation of existing faults whose normal lies in the 1 3 plane of a stress field with effective principal compressive stresses 1 2 3 is considered for the simplest frictional failure criterion n n p where and n are respectively the shear and normal stresses to the existing fault p is the fluid pressure and is the static friction for a plane oriented at to 1 the stress ratio for reactivation is 1 3 1 cot 1 tan this ratio has a minimum positive value at the optimum angle for reactivation given by 12tan 1 1 but reaches infinity when 2 beyond which 3 0 is a necessary condition for reactivation an important consequence is that for typical rock friction coefficients it is unlikely that normal faults will be reactivated as high angle reverse faults or thrusts as low angle normal faults unless the effective least principal stress is tensile

paleoclimate reconstruction based on the timing of speleothem growth and oxygen and carbon isotope composition in a cave located in the rain shadow in israel high resolution th 230 u 234 ages and delta 18 o and delta 13 c compositions of speleothems in ma ale efrayirn cave located to the east of the central mountain ridge of israel enable us to examine the nature of the rain shadow aridity during glacial and interglacial intervals speleothem growth occurred during marine glacial isotopic periods with no growth during the two last marine isotope interglacial intervals and during the peak of the last glacial maximum this contrasts with speleothem growth in caves located on the western flank of the central mountain ridge in the eastern mediterranean semiarid climatic zone which continued throughout the last 240 000 yr thus during glacial periods water reached both sides of the central mountain ridge a comparison of the present day rain and cave water isotopic compositions and amounts at the ma ale efrayim cave site with those on the western flank shows that evaporation and higher temperatures on the eastern flank are major influences on isotopic composition and the lack of rainfall the delta 18 o and delta 13 c profiles of the speleothems deposited between 67 000 and 25 000 yr b p match the general trends of the isotopic profiles of soreq cave speleothems suggesting a similar source eastern mediterranean sea and similar climatic conditions thus during glacial periods the desert boundary effectively migrated further south or east from its present day location on the eastern flank whereas interglacial periods appear to have been similar to the present with the desert boundary at the same position the decrease in overall temperature and a consequent reduction in the evaporation to precipitation ratios on the eastern flank are viewed as the major factors controlling the decay of the rain shadow effect during glacial periods c 2003 elsevier science usa all rights reserved

emplacement and deformation history of the western margin of the idaho batholith near mccall idaho influence of a major terrane boundary cretaceous plutons of the western margin of the idaho batholith were emplaced along and to the west of the major terrane boundary separating middle proterozoic and paleozoic continental rocks from mostly mesozoic accreted oceanic arc terranes of the blue mountain province this boundary is marked by a change in the lithology of pendants and inclusions within the batholith plutons form two newly named complexes of igneous and metamorphosed igneous rocks the hazard creek complex emplaced west of the boundary between the oceanic arc and the continental margin consists primarily of a series of variably deformed and metamorphosed quartz diorite to trondhjemite plutons the little goose creek complex which intruded the boundary between the oceanic arc and the continental margin is primarily porphyritic granodiorite to granite orthogneiss a preliminary u pb age of 111 ma for this porphyritic orthogneiss is a minimum age for the formation of the oceanic arc continent boundary the plutonic rocks were deformed both during and after emplacement in response to east west compressive stresses cretaceous deformation was localized along the boundary between the accreted terranes and the continental margin and is interpreted to have occurred after the formation of this boundary the major deformation of the hazard creek complex occurred during its emplacement the dominant fabric in the little goose creek complex is due to subsolidus ductile deformation the localization of two deformation events along the pre existing boundary between the accreted terranes and the continental margin suggests that a terrane boundary may form a long lasting crustal flaw

u pb studies of zircon cores and overgrowths and monazite implications for age and petrogenesis of the northeastern idaho batholith u pb isotopic studies of zircons many containing xenocrystic cores with euhedral overgrowths and monazite from igneous rocks and metasedimentary inclusions of the northeastern idaho batholith yield linear arrays on concordia diagrams we interpret these as mixing lines between an old component cores and a young component overgrowths and zircons without cores the lower intercept of such arrays with concordia may yield the minimum age of the rocks if the overgrowths and zircons without cores are discordant or the crystallization age if they are concordant monazites yield apparently concordant ages either equal or less than the lower intercept zircon ages the samples studied yield lower intercept ages ranging from 73 5 pm 6 m y foliated quartz diorite to 46 5 pm 1 m y feldspar megacryst granite ages obtained are consistent with crosscutting relations observed in the field upper intercepts yield ages of 1700 to 2349 m y these are interpreted to indicate the mean age of xenocrystic zir

paleoclimate and vegetation of the last glacial cycles in jerusalem from a speleothem record a speleothem isotopic record taken from jerusalem is used to reconstruct regional climate over the last 170 000 years glacial periods in jerusalem were generally cooler and wetter than the present climate stage 5e in the desert margin of jerusalem was extremely unstable dry and warm and instability persisted throughout the transition to glacial conditions the climate after stage 5e became gradually cooler and wetter over a 20 000 year interval and did not recover to interglacial conditions in stages 5c and 5a the 13 c varied by up to 12 from glacial stages 6 4 3 2 values of 10 to 12 that reflect dense c 3 vegetation above the studied cave and up to 0 in early stage 5 when there was probably complete loss of vegetation the climatic instability during interglacial periods is much larger than during glacial periods and glacial interglacial transitions do not behave the same in each climatic cycle in this region