upper crustal seismic structure of the mazury complex and mazowsze massif within east european craton in ne poland the large scale seismic experiment polonaise 97 polish lithospheric onsets an international seismic experiment was carried out in may 1997 in poland lithuania and germany its main purpose was to investigate the structure of the crust and the uppermost mantle in the region of the trans european suture zone tesz that lies between the east european craton eec and the palaeozoic platform this paper covers the interpretation of seismic data along the nw se trending 180 km long profile p5 located on the eec the recordings were of a high quality with seismic energy clearly visible along the whole profile we have not found waves refracted below the upper crust in first arrivals in the nw part of the profile we have delineated a high velocity body with the p wave velocity in the range of 6 5 6 75 km s in the upper crust it corresponds to the ketrzyn anorthosite massif within the mazury complex the mazowsze massif is rather uniformly characterized by p wave velocities 5 9 6 05 and 6 2 6 35 km s in two layers respectively sufficient s wave data were available to estimate the vp vs ratio as well as the poisson ratio being 1 80 0 277 in the high velocity body and 1 67 0 220 in the upper crust apart from the 2 d model along the profile results of 3 d modelling in the area of the p5 profile are presented using off line recordings we got p wave velocity field up to 8 km s below the p5 profile at the depth of about 40 km as well as horizontal extent of the high velocity body

correlation of reservoired gases using the carbon isotopic compositions of wet gas components the carbon isotopic compositions of the wet gas components particularly propane isobutane and normal butane have been found to be particularly valuable for correlating one reservoired gas with another the usefulness of these components for correlation results from their carbon isotopic compositions reflecting both the nature of their source and their maturity this source control is strongest for gases derived from the more highly structured types of kerogen i e woody coaly type iii although the wet gas components carbon isotopic compositions of most gases are at least partly controlled by their source for levels of maturity below the point at which thermal destruction of the wet components occurs as a result the wet gas components are found to provide more ositive correlations than is methane alone three exploration examples illustrate the use of the carbon isotopic compositions of the wet gas components for correlation the leduc reef trend of alberta canada the sleipner area in the north sea and the lena field offshore louisiana united states the three examples also illustrate the need to integrate geochemical interpretations with regional geology to obtain a good understanding of the hydrocarbon source

diagenesis and reservoir quality of the aldebaran sandstone denison trough east central queensland australia the lower permian aldebaran sandstone is the principal hydrocarbon reservoir in the denison trough bowen basin east central queensland australia it accumulated in a wide range of fluvio deltaic and nearshore marine environments detailed petrological study of the unit by thin section x ray diffraction scanning electron microscopy electron microprobe and isotopic analysis reveals a complex diagenetic history which can be directly related to depositional environment initial composition and burial temperature history early diagenetic effects included the precipitation of pyrite siderite and illite smectite rims o smow 8 9 to 11 3 deep burial effects included physico chemical compaction and the formation of quartz overgrowths siderite c pdb 34 0 to 11 5 o 0 7 to 22 7 illite illite smectite and ankerite c 9 3 to 4 9 o 7 6 to 14 4 involved fluids were in part connate meteoric water derived from compaction of the underlying freshwater reids dome beds important post maximum burial effects controlled by deep meteoric influx from the surface were ankerite and labile grain dissolution and formation of kaolinite o 7 8 to 8 9 d 115 to 99 calcite c 9 5 to 0 9 o 9 0 to 20 0 and dawsonite c 4 0 to 2 3 o 9 8 to 19 8 the formation of dawsonite reflecting eventual stagnation of the aquifer entrapment of contained hydrocarbons was a relatively recent event which may be continuing today reservoir quality varies from marginal to good in the west to poor in the east with predictable trends being directly linked to depositional environment and diagenesis

a 10 15 yr modulation cycle of enso intensity abstract this study examines the slow modulation of el nino southern oscillation enso intensity and its underlying mechanism a 10 15 yr enso intensity modulation cycle is identified from historical and paleoclimate data by calculating the envelope function of boreal winter nino 3 4 and nino 3 sea surface temperature sst indices composite analyses reveal interesting spatial asymmetries between el nino and la nina events within the modulation cycle in the enhanced intensity periods of the cycle el nino is located in the eastern tropical pacific and la nina in the central tropical pacific the asymmetry is reversed in the weakened intensity periods el nino centers in the central pacific and la nina in the eastern pacific el nino and la nina centered in the eastern pacific are accompanied with basin scale surface wind and thermocline anomalies whereas those centered in the central pacific are accompanied with local wind and thermocline anomalies the el nino la nina asymmetries provide a possible m

the normality of el nino the amplitude of the el nino southern oscillation enso would be normally distributed if the coupled pacific ocean atmosphere were a linear system forced by gaussian weather noise moment estimates of skewness and kurtosis demonstrate that this is not the case for monthly mean anomalies in pacific sea surface temperatures during 1950 97 the noted predominance of el nino events compared to la nina events is related to the high skewness in the eastern pacific skewness and kurtosis both exhibit an intriguing geographical variation from positive in the eastern to negative in the western pacific we have also examined nino 3 indices generated by three climate models having widely different complexity these exhibit a wide range of skewness and kurtosis values rather different from those found for the observations skewness and kurtosis can be used to diagnose non linear processes and provide powerful tools for validating models and for testing observed sea surface temperatures for the presence of possible climate change

ferro potassic a type granites and related rocks in ne poland and s lithuania west of the east european craton the present study of monzodiorite quartz monzodiorite monzonite quartz syenite granodiorite and rapakivi like granite surrounding the suwalki ketrzyn and sejny anorthosite norite and gabbro plutons or forming separate bodies in northern poland and southern lithuania has resulted in the recognition of a specific suite with amcg affinity the bodies belonging to the mazury and veisiejai complexes are aligned to e w trending lineaments in southern lithuania and northern poland with a continuation through the baltic sea into south central sweden in the west and into nw belarus in the east the rocks of the suite form a continuous series ranging from 45 to 75 sio2 with no indication of the classical daly gap between mafic and felsic rocks the mazury and veisiejai complexes chemically belong to the ferro potassic alkali calcic type of rocks and are comparable with the amcg suite e g in rogaland southern norway the most acidic varieties of the granitoids approach the classic rapakivi granites in their petrogenetic characteristics elevated contents of incompatible elements and ree and hence have a type affinities the granitoids are assigned to the post collisional granite field the overall evolution from mafic to acidic rocks is characterized by well defined trends which most probably represent a liquid line of descent fractional crystallization with or without assimilation and hybridization can account for the continuous evolution from mafic to acidic members the formation of the suite is concentrated in the timespan covering almost 50 myr from 1 55 to 1 5 ga the most felsic rocks yield ages of ca 1 5 ga which are very similar to the kabeliai granites further east in southeastern lithuania cooling and local mylonitization proceeded until 1 4 ga hornblende and biotite 40 ar 39 ar ages

seismic basement in poland the area of contact between precambrian and phanerozoic europe in poland has complicated structure of sedimentary cover and basement the thinnest sedimentary cover in the mazury belarus anteclize is only 0 3 1 km thick increases to 7 8 km along the east european craton margin and 9 12 km in the trans european suture zone tesz the variscan domain is characterized by a 1 to 2 km thick sedimentary cover while the carpathians are characterized by very thick sediments up to c 20 km the map of the basement depth is created by combining data from geological boreholes with a set of regional seismic refraction profiles these maps do not provide data about the basement depth in the central part of the tesz and in the carpathians therefore the data set is supplemented by 32 models from deep seismic sounding profiles and a map of a high resistivity low conductivity layer from magnetotelluric soundings identified as a basement all of these data provide knowledge about the basement depth and of p wave seismic velocities of the crystalline and consolidated type of basement for the whole area of poland finally the differentiation of the basement depth and velocity is discussed with respect to geophysical fields and the tectonic division of the area

how well do current climate models simulate two types of el nino in this study we evaluate the fidelity of current climate models in simulating the two types of el nino events using the pre industrial output in cmip3 archives it is shown that a few climate models simulate the two types of el nino events to some extent while most of the models have serious systematic problems in simulating distinctive patterns of sea surface temperature sst and precipitation anomaly associated with the two types of el nino that is they tend to simulate a single type of el nino it is shown that the ability of climate models in simulating the two types of el nino is related to the sensitivity of the atmospheric responses to the sst anomaly patterns models whose convective location is shifted to the east west as the sst anomaly center moves to the east west tends to simulate the two types of el nino events successfully on the other hand models whose location of convective anomaly is confined over the western or central pacific tends to simulate only the single type of el nino event it is also shown that the confinement of the convective anomaly over the western or central pacific is closely linked to the dry bias and the associated cold bias over the eastern pacific that is because positive el nino sst anomalies over the eastern pacific cannot increase local convection effectively when the total ssts are still too cold due to a cold bias this implies that the realistic simulation of climatology especially over the equatorial eastern pacific is essential to the successful simulation of the two types of el nino

decadal amplitude modulation of two types of enso and its relationship with the mean state in this study we classified two types of el nino southern oscillation enso events within the decadal enso amplitude modulation cycle using a long term coupled general circulation model simulation we defined two climate states strong and weak enso amplitude periods and separated the characteristics of enso that occurred in both periods there are two major features in the characteristics of enso the first is the asymmetric spatial structure between el nino and la nina events the second is that the el nino la nina asymmetry is reversed during strong and weak enso amplitude periods el nino events during strong weak enso amplitude periods resemble the eastern pacific central pacific el nino in terms of the spatial distribution of sea surface temperature anomalies ssta and physical characteristics based on heat budget analysis the spatial pattern of the thermocline depth anomaly for strong weak el nino is identical to that for weak strong la nina but for an opposite sign and slightly different amplitude the accumulated residuals of these asymmetric anomalies dominated by an east west contrast structure could feed into the tropical pacific mean state moreover the residual pattern associated with el nino la nina asymmetry resembles the first principal component analysis pca mode of tropical pacific decadal variability indicating that the accumulated residuals could generate the change in climate state thus the intensified enso amplitude yields the warm residuals due to strong el nino and weak la nina over the eastern tropical pacific this linear relationship between enso and the mean state is strong during the mature phases of decadal oscillation but it is weak during the transition phases furthermore the second pca mode of tropical pacific decadal variability plays an important role in changing the phase of the first mode consequently the feedback between enso and the mean state is positive feedback to amplify the first pca mode whereas the second pca mode is a negative feedback to lead the phase change of the first pca mode due to their lead lag relationship these features could be regarded as evidence that the decadal change in properties of enso could be generated by the nonlinear interaction between enso and the mean state on a decadal to interdecadal time scale

statistical evidence for the natural variation of the central pacific el nino 1 extensive studies claimed that the central equatorial pacific cp el nino has occurred more frequently and strongly than the eastern equatorial pacific el nino in recent years to explain this phenomenon spatial patterns and principal component time series from several sea surface temperature sst data sets in the tropical pacific are analyzed for the period of 1951 2010 cyclostationary empirical orthogonal function analysis separates two modes of sst variability which explain about 50 and 10 of the total sst variability respectively their spatial and temporal patterns are similar among the different sst data sets the first mode captures the typical el nino pattern while the second mode is a dipole pattern in the tropical pacific the two modes are by definition uncorrelated over the analysis period but are in phase since the late 1990s superposition of the two modes results in a significant warming in the cp region which is a potential explanation for a more frequent occurrence of the cp el nino in the recent decades similar analysis is conducted based on the 500 year data from the geophysical fluid dynamics laboratory climate model version 2 1 under the preindustrial condition the result is generally consistent with the observations yielding occasional in phase relationship between the two modes thus it cannot be ruled out that a more frequent occurrence of the cp el nino in recent years is a natural feature of the equatorial climate system

analysis of the southward wind shift of enso in cmip5 models abstractduring the mature phase of el nino southern oscillation enso events there is a southward shift of anomalous zonal winds sws which has been suggested to play a role in the seasonal phase locking of enso motivated by the fact that coupled climate models tend to underestimate this feature this study examines the representation of the sws in phase 5 of the coupled model intercomparison project cmip5 it is found that most models successfully reproduce the observed sws although the magnitude of the zonal wind stress anomaly is underestimated several significant differences between the models with and without the sws are identified including biases in the magnitude and spatial distribution of precipitation and sea surface temperature sst anomalies during enso multiple linear regression analysis suggests that the climatological meridional sst gradient as well as anomalous enso driven convective activity over the northwest pacific both might play a role in controlling the sws while the mode

diverse influences of enso on the east asian western pacific winter climate tied to different enso properties in cmip5 models the influence of el nino southern oscillation enso on the east asian western pacific eawp climate in boreal winter is investigated in the phase 5 of the coupled model intercomparison project cmip5 model results and then compared to that in the phase 3 cmip3 results in particular the role played by the differences among models in enso properties including the amplitude and longitudinal extension of enso s sea surface temperature sst pattern is analyzed results show that an eastward shrinking of enso s sst pattern leads to quite weak circulation and climatic responses over the eawp regions in the models on the contrary a westward expansion of the sst pattern shifts the anomalous walker circulation too far west the resultant precipitation anomalies and lower tropospheric atmospheric rossby wave responses both extend unrealistically into the indian ocean and the hemispheric asymmetry of the rossby wave response is missing all these features lead to unrealistic climatic impacts of ensoover the eawp regions in contrasttothe abovetwocases areasonablelongitudinalextensionof enso s sst pattern corresponds to better enso teleconnections over the eawp regions nevertheless the atmospheric responses over the western pacific are still located farther west than observed implying a common bias of cmip5 models in this case a larger amplitude of enso variability to some extent helps to reduce model biases and facilitate better climatic responses to enso in the eawp regions compared with cmip3 models cmip5 models perform better in representing enso s impacts on the east asian winter climate

interannual variability in a tropical atmosphere ocean model influence of the basic state ocean geometry and nonlinearity abstract the behavior of a tropical coupled atmosphere ocean model is analyzed for a range of different background states and ocean geometries the model is essentially that of cane and zebiak for the tropical pacific except only temporally constant background states are considered here for realistic background states and ocean geometry the model solutions feature oscillations of period of 3 5 yr by comparing the full model solution with a linearized version of the model it is shown that the basic mechanism of the oscillation is contained within linear theory a simple linear analog model is derived that describes the nature of the interannual variability in the coupled tropical atmosphere ocean system the analog model highlights the properties that produce coupled atmosphere ocean instability in the eastern ocean basin and the equatorial wave dynamics in the western ocean basin that are responsible for a delayed negative feedback into this instability growth the growth rate of the local instabil

geochronology and structural relationships of mesothermal gold mineralization in the palaeoproterozoic jokisivu prospect southern finland the palaeoproterozoic svecofennian orogen in southern finland contains a number of orogenic gold occurrences the jokisivu gold deposit comprising auriferous quartz veins is hosted by syn tectonic quartz diorites to gabbros mineralization occurs in approximately wnw ese and wsw ene trending shear zones which probably branch from regional scale nw se trending shears ore zone fabrics post date regional scale folding and the metamorphic peak and can be correlated with late svecofennian regional shear tectonics d 6 1 83 1 78 ga indicating that mineralization formed during the late stages of orogenic evolution sims and tims u pb dating of three samples place tight constraints on the age of gold mineralization zircons from both unaltered and altered quartz diorites have ages of 1884 4 ma and 1881 3 ma respectively these are interpreted as the crystallization age of the rock and as providing the maximum age for mineralization zircon rims from an altered quartz diorite from the ore zone give ages of c 1802 15 ma which overlap with the 1801 18 ma titanite mean pb pb age from the ore zone the ages are similar to the age of the pegmatite dyke that cuts the ore zone and whose zircon age of 1807 3 ma is approximately the same as the 1791 2 ma monazite age tims giving the minimum age of the gold mineralization the mineralization and its structural framework can be correlated with coeval late svecofennian shear tectonics related to wnw ese oriented shortening in southern finland extensive c 1 8 ga granite magmatism shear zone development and associated gold mineralization are of regional importance also in the northern and western fennoscandian shield finnish lapand and sweden a cordilleran type setting can explain the widespread distribution of magmatism and gold mineralization associated with shortening as well as the required heat source triggering hydrothermal fluid flow along shear zones

noble gases in crude oils from the paris basin france implications for the origin of fluids and constraints on oil water gas interactions in order to investigate the potential of noble gases to trace the dynamics of oil reservoirs we have analysed the abundance and isotopic composition of all noble gases he ne ar kr and xe in crude oils from the paris basin france using a new extraction and purification procedure the main oil reservoirs are presently located in the jurassic dogger limestone and in the triassic keuper sandstone but hydrocarbons originated from a common source rock formation located in the interbedded liassic sequence despite this common origin the abundance and isotopic ratios of the noble gases differ between the dogger and the keuper the isotopic compositions of kr and xe are indistinguishable from that of air 3he 4he ratios higher than those predicted from radiogenic production in the sediments or in the crust are attributed to the occurrence of mantle derived 3he in the basin each sedimentary sequence is characterised by well defined and homogeneous 21ne 22ne and 40ar 36ar ratios which average 0 0306 0 0008 and 312 10 for the dogger and 0 0367 0 0012 and 664 30 for the keuper respectively the main source of radiogenic noble gases appears to be the continental crust underlying the basin with possible regional contributions of noble gas isotopes produced in the sediments the helium and argon isotopic ratios of the dogger oils are very similar to those observed in geothermal waters flowing in the dogger aquifer throughout the basin demonstrating that noble gases in oils derive from associated groundwaters oil reservoirs in the paris basin therefore accumulate noble gases from wide regions of the continental crust through cross formational flow of groundwaters and subsequent partitioning into oil this observation implies that noble gases cannot be directly used to date oils but can provide time constraints if 1 water oil interactions are quantified and 2 the residence time as well as the noble gas characteristics of associated groundwaters are known oil water gas partitioning processes are well recorded in the fractionation of noble gas elemental abundance two distinct processes have been identified 1 accumulation of atmosphere derived ang and radiogenic noble gases both initially dissolved in groundwaters resulting in a positive correlation between absolute amount of ang and the extent of heavy noble gas fractionation and 2 subsequent fractional degassing resulting in a negative correlation between ang abundance and heavy noble gas fractionation degassing is particularly evident for the keuper oils and might have occurred in the reservoirs following hydrodynamic gas stripping the ang abundance in the dogger reservoirs requires that about one order of magnitude more water than presently observed has interacted with the oil given current estimates of the residence time for groundwaters in the dogger aquifer the duration of oil water interaction is in qualitative agreement with a palaeocene oligocene age for the major episode of secondary oil migration in the paris basin high xenon contents in keuper reservoirs suggest that they have experienced hydrodynamic interactions between flowing waters and oils for long time and that the trias might have reached hydrostatic condition only recently

palaeoproterozoic accretionary processes in fennoscandia abstract accretionary processes contributed to major continental growth in fennoscandia during the palaeoproterozoic mainly from 2 1 to 1 8 ga the composite svecofennian orogen covers c 1 10 6 km 2 and comprises the lapland savo fennia svecobaltic and nordic orogens it is a collage of 2 1 2 0 ga microcontinents and 2 02 1 82 ga island arcs attached to the archaean karelian craton between 1 92 and 1 79 ga andean type vertical magmatic additions especially at c 1 89 and c 1 8 ga were also important in the continental growth the palaeoproterozoic crust is the end product of accretionary growth continental collision and orogenic collapse preserved accretional sections are found in areas where docking of rigid blocks has prevented further shortening the pirkanmaa belt represents a composite accretionary prism and other preserved palaeosubduction zones are identified in the gulf of bothnia and the baltic sea areas in the southern segment of the lapland savo orogen collision between the archaean continent lower plate and the palaeoproterozoic arc microcontinent assembly upper plate produced a special type of lateral crustal growth the archaean continental edge decoupled from its mantle during initial collision and overrode the arc and its mantle during continued collision

the role of mean state on changes in el nino s flavor recently many studies have argued for the existence of two types of el nino phenomena based on different spatial distributions the conventional el nino or eastern pacific ep el nino and the central pacific cp el nino here we investigate the decadal modulation of cp el nino occurrences using a long term coupled general circulation model simulation focusing in particular on the role of climate state in the regime change between more and fewer cp el nino events the higher occurrence regime of the cp el nino coincides with the lower occurrence regime of ep el nino and vice versa the climate states associated with these two opposite regimes resemble the leading principal component analysis pca modes of tropical pacific decadal variability indicating that decadal change in climate state may lead to regime change in terms of two different types of el nino in particular the higher occurrence regime of cp el nino is associated with a strong zonal gradient of mean surface temperature in the equatorial pacific along with a strong equatorial trade wind over the area east of the dateline in addition the oceanic variables the mixed layer depth and the thermocline depth show values indicating increased depth over the western to central pacific the aforementioned climate states obviously intensify zonal advective feedback which promotes increased generation of the cp el nino frequent cp el nino occurrences are not fully described by oceanic subsurface dynamics and dynamical or thermodynamical processes in the ocean mixed layer and air sea interaction are important contributors to the generation of the cp el nino furthermore the atmospheric response with respect to the ssta tends to move toward the west which leads to a weak air sea coupling over the eastern pacific these features could be regarded as evidence that the climate state can provide a selection mechanism of the el nino type

asymmetry in the duration of el nino and la nina abstract el nino and la nina are not a simple mirror image but exhibit significant differences in their spatial structure and seasonal evolution in particular sea surface temperature sst anomalies over the equatorial pacific cold tongue are larger in magnitude during el nino compared to la nina resulting in positive skewness of interannual sst variations the associated atmospheric deep convection anomalies are displaced eastward during el nino compared to la nina because of the nonlinear atmospheric response to sst in addition to these well known features an analysis of observational data for the past century shows that there is a robust asymmetry in the duration of el nino and la nina most el ninos and la ninas develop in late boreal spring summer when the climatological cold tongue is intensifying and they peak near the end of the calendar year after the mature phase el ninos tend to decay rapidly by next summer but many la ninas persist through the following year and often reintensify in

influence of tropical pacific sea surface temperature on the genesis of gulf stream cyclones abstractthis study investigates the relationship between tropical pacific sea surface temperature sst variability and cyclogenesis over the gulf stream region of the north atlantic a cyclone identification scheme and lagrangian trajectories are used to compare preferred cyclogenesis locations and precyclogenesis flow paths associated with three patterns of tropical pacific sst variability eastern pacific ep el nino central pacific cp el nino and la nina during ep el nino and la nina winters the upper level precyclogenesis flow takes a subtropical path over north america and gulf stream cyclogenesis predominantly occurs under the north atlantic jet entrance which is the climatologically preferred location in contrast during cp el nino winters when the warmest sst anomalies occur in the central tropical pacific the precyclogenesis flow takes a northern path across north america and gulf stream cyclogenesis tends to occur farther north under the jet exit the shift in preferred cyclogenesis

reversed spatial asymmetries between el nino and la nina and their linkage to decadal enso modulation in cmip3 models abstractthis study examines preindustrial simulations from coupled model intercomparison project phase 3 cmip3 models to show that a tendency exists for el nino sea surface temperature anomalies to be located farther eastward than la nina anomalies during strong el nino southern oscillation enso events but farther westward than la nina anomalies during weak enso events such reversed spatial asymmetries are shown to force a slow change in the tropical pacific ocean mean state that in return modulates enso amplitude cmip3 models that produce strong reversed asymmetries experience cyclic modulations of enso intensity in which strong and weak events occur during opposite phases of a decadal variability mode associated with the residual effects of the reversed asymmetries it is concluded that the reversed spatial asymmetries enable an enso tropical pacific mean state interaction mechanism that gives rise to a decadal modulation of enso intensity and that at least three cmip3 models realistically simu

moho depth across the trans european suture zone from p and s receiver functions the mohorovicic discontinuity moho for short which marks the boundary between crust and mantle is the main first order structure within the lithosphere geodynamics and tectonic evolution determine its depth level and properties here we present a map of the moho in central europe across the teisseyre tornquist zone a region for which a number of previous studies are available our results are based on homogeneous and consistent processing of p and s receiver functions for the largest passive seismological data set in this region yet consisting of more than 40 000 receiver functions from almost 500 station besides we also provide new results for the crustal vp vs ratio for the whole area our results are in good agreement with previous more localized receiver function studies as well as with the interpretation of seismic profiles while at the same time resolving a higher level of detail than previous maps covering the area for example regarding the eifel plume region rhine graben and northern alps the close correspondence with the seismic data regarding crustal structure also increases confidence in use of the data in crustal corrections and the imaging of deeper structure for which no independent seismic information is available in addition to the pronounced stepwise transition from crustal thicknesses of 30 km in phanerozoic europe to more than 45 beneath the east european craton we can distinguish other terrane boundaries based on moho depth as well as average crustal v p v s ratio and moho phase amplitudes the terranes with distinct crustal properties span a wide range of ages from palaeoproterozoic in lithuania to cenozoic in the alps reflecting the complex tectonic history of europe crustal thickness and properties in the study area are also markedly influenced by tectonic overprinting for example the formation of the central european basin system and the european cenozoic rift system in the areas affected by cenozoic rifting and volcanism thinning of the crust corresponds to lithospheric updoming reported in recent surface wave and s receiver function studies as expected for thermally induced deformation the same correlation applies for crustal thickening not only across the trans european suture zone but also within the southern part of the bohemian massif

the long term fate of co2 in the subsurface natural analogues for co2 storage abstract co 2 is a common gas in geological systems so that planned storage of co 2 in the subsurface may do no more than mimic nature natural co 2 has a wide number of sources that can be at least partly identified by carbon stable isotope geochemistry three pairs of case studies with different reservoir characteristics and co 2 contents have been examined to assess the natural impact of adding co 2 to geological systems carbonate minerals partially dissolve when co 2 is added simply because the co 2 dissolves in water and forms an acidic solution therefore carbonate minerals in the subsurface are not capable of sequestering secondary co 2 the addition of co 2 to a pure quartz sandstone or a sandstone in which the supply of reactive aluminosilicate minerals has been exhausted by excess natural co 2 addition will have no consequences the co 2 will simply saturate the water and then build up as a separate gas phase the addition of co 2 to carbonate cemented sandstone without reactive aluminosilicate minerals will induce a degree of carbonate mineral dissolution but no solid phase sequestration of the added co 2 when co 2 is naturally added to sandstones it will induce combined aluminosilicate dissolution and carbonate cementation if the aluminosilicate minerals contain calcium or magnesium or possibly iron examination of a co 2 filled porous sandstone with abundant reactive aluminosilicate minerals that received a huge co 2 charge about 8000 to 100 000 years ago reveals minimal evidence of solid phase sequestration of the added co 2 this indicates that either dissolution of reactive aluminosilicates or precipitation of carbonate minerals is relatively slow it is very likely that the slow dissolution of reactive aluminosilicates is the rate limiting step solid phase sequestration of co 2 occurs only when reactive aluminosilicates are present in a rock and when the system has had many tens to hundreds of thousands of years to equilibrate the two critical aspects of the behaviour of co 2 when injected into the subsurface are 1 that the rock must contain reactive ca and mg aluminosilicates and 2 that reaction to produce carbonate minerals is extremely slow on a human timescale the reactive minerals include anorthite zeolite smectite and other fe and mg clay minerals such minerals are absent from clean sandstones and limestones but are present in dirty standstones lithic arenites which are mineralogically immature and some mudstones the analysis of geological analogues shows that injection of co 2 into carbonate bearing rocks that do not contain reactive minerals will induce dissolution of the carbonate whether it is a matrix cement rock fragment fault seal or part of a top sealing mudstone

observations of warm water volume changes in the equatorial pacific and their relationship to el nino and la nina abstract this paper describes observed changes in surface winds sea surface temperature sst and the volume of water warmer than 20 c wwv in the equatorial pacific ocean for the period 1980 99 the purpose is to test recent hypotheses about the relationship between variations in wwv and the el nino southern oscillation enso cycle the results confirm inferences based on theory models and previous empirical analyses using proxy data namely sea level that enso involves a recharge and discharge of wwv along the equator and that the cyclic nature of enso results from a disequilibrium between zonal winds and zonal mean thermocline depth the authors also find that the magnitude of enso sst anomalies is directly related to the magnitude of zonal mean wwv anomalies furthermore for a given change in equatorial wwv the corresponding warm el nino sst anomalies are larger than the corresponding cold la nina anomalies this asymmetry between the warm and cold phases of the enso cycle implies differences

analysis of co2 leakage through low permeability faults from natural reservoirs in the colorado plateau east central utah the numerous co 2 reservoirs in the colorado plateau region of the united states are natural analogues for potential geologic co 2 sequestration repositories to better understand the risk of leakage from reservoirs used for long term underground co 2 storage we examine evidence for co 2 migration along two normal faults from a reservoir in east central utah co 2 charged springs geysers and a hydrocarbon seep are localised along these faults these include natural springs that have been active for long periods of time and springs that were induced by recent drilling the co 2 charged spring waters have deposited travertine mounds and carbonate veins the faults cut siltstones shales and sandstones and the fault rocks are fine grained clay rich gouge generally thought to be barriers to fluid flow the geologic and geochemical data are consistent with these faults being conduits for co 2 to the surface consequently the injection of co 2 into faulted geologic reservoirs including faults with clay gouge must be carefully designed and monitored to avoid slow seepage or fast rupture to the biosphere

eurobridge 95 deep seismic profiling within the east european craton abstract the eurobridge deep seismic sounding dss profile is a key component of a europrobe project to examine palaeoproterozoic processes of continental collision and crustal accretion its purpose is to establish the deep lithospheric structure of the east european craton between the exposed proterozoic and archaean complexes of the baltic and ukrainian shields in 1994 a dss experiment was recorded across the baltic sea from vastervik sweden to shventoji lithuania we report on eurobridge 95 the first onshore stage of the seismic profile it is 280 km long recorded from nw to se on the lithuanian part of the east european platform traversing the proterozoic west lithuanian granulite domain wlg and east lithuanian belt el terranes explosive shots of up to 1000 kg tnt were detonated at 10 shotpoints sp01 sp10 at intervals of about 30 km arrivals were recorded at 76 3 component seismograph stations with an average station spacing of 3 5 km providing high quality records a 11th shot of 3000 kg sp00 was fired in the baltic sea close to gotland raytracing analysis of refracted and reflected p waves has been used to determine a 2 dimensional seismic velocity model for the crust and uppermost mantle below eurobridge 95 the thickness of the phanerozoic sedimentary cover decreases from 2 2 km in the north west near the baltic sea coast to 0 4 km at the south east end of the profile near the lithuania belarus border crust in the north west and central part of profile consists of two major layers with a thickness of about 44 km increasing to 50 km and three layers in the south east crystalline upper crust is about 20 km thick thinning in the south east with p wave velocities of 6 0 6 3 km s a very weak low velocity zone with a velocity contrast of 0 1 0 2 km s occurs at 8 13 km depth below the north west and central part of the profile only lower crust exhibits velocities of commonly 6 5 6 9 km s and thickens to the south east with p wave velocities up to 7 0 km s in the deepest parts crystalline crust is characterised by low velocity gradients and small velocity contrasts at most seismic boundaries major lateral changes in crustal velocity structure at all depths can be spatially correlated with the wlg el boundary determined from near surface geological information very strong reflections from the moho boundary are observed the mantle p wave velocity immediately below the crust is 8 2 8 35 km s a reflector in the lower lithosphere at a depth of almost 70 km was found below lithuania reflectivity modelling of the gotland shot data suggests that this interface is absent offshore where mantle velocities are lower the dss model supports the interpretation of the wlg and el as terranes of proterozoic age forming part of fennoscandia later modification of crustal structure may have occurred possibly by a mantle heating episode centred on the baltic sea area

the impact of enso on the south atlantic subtropical dipole mode abstractthe impact of el nino southern oscillation enso on the south atlantic subtropical dipole mode sasd is investigated using both observations and model simulations the sasd is the dominant mode of coupled ocean atmosphere variability in the south atlantic this study focuses on austral summer when both enso and sasd peak it is shown that negative sasd events are associated with central pacific el nino events by triggering the pacific south american wave train psa the latter resembles the third leading mode of atmospheric variability in the southern hemisphere psa2 and causes a weakening and meridional shift of the south atlantic subtropical high which then generates the negative sasd events on the other hand a strengthening of the south atlantic subtropical high related to central la nina teleconnections causes positive sasd events the results herein show that the psa2 triggered by central pacific enso events connects the tropical pacific to the atlantic this connection is absent f

a late paleoproterozoic 1 80 ga subduction related mafic igneous suite from lomza ne poland the lomza orthoamphibolites in the crystalline basement of ne poland dated at 1802 9 ma by shrimp zircon u pb are characterized by high incompatible and ree element contents these features the low nb and the position of the rock compositions on la y nb zr nb zr and zr nb y tectonomagmatic discrimination diagrams suggest that the metavolcanics formed in a subduction setting possibly within a continental margin island arc the likely extension of the belt of paleoproterozoic mafic magmatism from latvia and lithuania into ne poland provides convincing evidence for the existence of an active plate margin in that region at that time

precambrian domains in lithuania evidence of terrane tectonics abstract the west lithuanian granulite wlg and east lithuanian domains eld form the proterozoic basement of lithuania and can be distinguished on the basis of differing structural patterns lithologies and evolutionary histories they are juxtaposed along the mid lithuanian suture zone mlsz in the wlg the main lithotectonic complexes comprise felsic and intermediate mostly metasedimentary granulites in the south west and mafic metaigneous granulites in the north east the former are interpreted as marine metapelites while most of the mafic ones have been derived from island arc tholeiites these rock complexes trend nw se and are marked by contrasting gravity and magnetic anomalies ne and e w striking faults and shear zones complicate the potential field patterns sets of nw trending anomalies also extend from lithuania across the baltic sea to south central sweden and indicate that the wlg complexes continue into the baltic fennoscandian shield voluminous anatectic granites alternate with the metapelites whereas the mafic granulites occur together with enderbites and charnockites in the eld the main structures produce strong nne ssw oriented gravity and magnetic anomalies which trend parallel to the belarus baltic granulite belt bbg and other terranes situated still farther east the eld is composed of metasedimentary rocks interpreted as one time graywackes shales and dolomites accumulated in continental margin arc and shallow water basinal environments amphibolites and gabbros with morb and iat characteristics and voluminous granitoids are also present the coexistence of juvenile mafic rocks with continental margin and shelf sediments suggests an oceanic back arc setting the two lithuanian basement domains display contrasting metamorphic histories that suggest separate developments before the eventual amalgamation in the wlg the metapelites indicate peak metamorphism at high temperatures up to 850 900 c and moderate pressures 8 10 kbar this was followed by cooling and reheating and then an uplift event repeated magmatic underplating accompanied the metamorphism in the eld in contrast the rocks have been subjected to comprehensive metamorphism under moderate amphibolite facies conditions that metamorphism however was not uniform throughout the metasediments in the east have recorded pressures similar to those in the neighbouring bbg 7 8 kbar but lower temperatures 650 680 c while in the central and western parts of the eld metamorphism occurred at ca 480 580 c with pressures increasing from 3 4 kbar in the centre to 6 kbar close to the western boundary reheating to 700 c due to a ca 1 5 ga magmatic event is characteristic the mlsz which separates the two lithuanian basement domains from each other is a n s oriented ca 30 50 km wide westward plunging crustal discontinuity marked by magnetic and gravity highs mafic and felsic intrusions and sheared rocks crustal thicknesses change from 42 44 km in the west to 50 km in the eastern side of the zone which also truncates a crustal low velocity layer characteristic of the wlg the amalgamation of the wlg and eld along the mlsz occurred at ca 1 71 1 66 ga after which time both domains were affected by the same post kinematic anorogenic magmatism ca 1 58 1 45 ga ago that event and related shearing were responsible for some ultimate refragmentation of the lithuanian basement terranes

carbon isotope fractionation during natural gas generation from kerogen abstract in petroleum exploration it is important to be able to determine the origin of any gas which is found this paper describes a new method of estimating the source type and maturity of a gas based on a rayleigh fractionation model kerogen is divided conceptually into a labile dominantly oil generating fraction and a refractory gas prone component 13 c of methane from either kerogen type and ethane propane and butane for gases from labile kerogen can be defined as a function of 13 c of the gas precursor groups in kerogen a kinetic isotope fractionation factor k and the extent of gas generation the isotopic ratio of the methane precursors relative to bulk kerogen determined from laboratory pyrolysis are 17 5 for labile kerogen and 1 4 for refractory kerogen values for ethane propane and butane from labile kerogen based on field correlations are 4 9 2 2 and 1 6 respectively the corresponding fractionation factors are 0 9892 0 9919 0 9947 and 0 9975 for methane ethane propane and butane respectively from labile kerogen and 0 9984 for methane from refractory kerogen using these parameters summary diagrams are constructed which allow differentiation of these sources from each other and from biogenic gases and cracked oil and recognition of gases of mixed origin if an independent estimate of 13 c for the source kerogen is possible then 13 c of the gas components can be used to estimate maturity in terms of the gas generation index the fraction of gas potential which has been realized

twentieth century enso characteristics in the ipcc database in this paper we assess and compare to observations the spatial characteristics of the twentieth century enso sst variability simulated by 23 models of the ipcc ar4 cmip3 database the analysis is confined to the sst anomalies along the equatorial pacific and is based on the use of a non linear neural classification algorithm the self organizing maps systematic biases include a larger than observed proportion for modelled enso maximum variability occurring in the western pacific no clear relationship is found between this bias and the characteristics of the modelled mean state bias in the equatorial pacific this bias is mainly related to a misrepresentation of both el nino and la nina termination phases for most of the models in contrast the onset phase is quite well simulated modelled el nino and la nina peak phases display an asymmetric bias whereas the main bias of the modelled el nino peak is to exhibit a maximum in the western pacific the simulated la nina bias mainly occurs in the central pacific in addition some models are able to capture the observed el nino peak characteristics while none of them realistically simulate la nina peaks it also arises that the models closest to the observations score unevenly in reproducing the different phases preventing an accurate classification of the models quality to reproduce the overall enso like variability

analysis of the non linearity in the pattern and time evolution of el nino southern oscillation in this study the observed non linearity in the spatial pattern and time evolution of el nino southern oscillation enso events is analyzed it is shown that enso skewness is not only a characteristic of the amplitude of events el ninos being stronger than la ninas but also of the spatial pattern and time evolution it is demonstrated that these non linearities can be related to the non linear response of the zonal winds to sea surface temperature sst anomalies it is shown in observations as well as in coupled model simulations that significant differences in the spatial pattern between positive el nino versus negative la nina and strong versus weak events exist which is mostly describing the difference between central and east pacific events central pacific events tend to be weak el nino or strong la nina events in turn east pacific events tend to be strong el nino or weak la nina events a rotation of the two leading empirical orthogonal function modes illustrates that for both el nino and la nina extreme events are more likely than expected from a normal distribution the bjerknes feedbacks and time evolution of strong enso events in observations as well as in coupled model simulations also show strong asymmetries with strong el ninos being forced more strongly by zonal wind than by thermocline depth anomalies and are followed by la nina events in turn strong la nina events are preceded by el nino events and are more strongly forced by thermocline depth anomalies than by wind anomalies further the zonal wind response to sea surface temperature anomalies during strong el nino events is stronger and shifted to the east relative to strong la nina events supporting the eastward shifted el nino pattern and the asymmetric time evolution based on the simplified hybrid coupled rechoz model of enso it can be shown that the non linear zonal wind response to sst anomalies causes the asymmetric forcings of enso events this also implies that strong el ninos are mostly wind driven and less predictable and strong la ninas are mostly thermocline depth driven and better predictable which is demonstrated by a set of 100 perfect model forecast ensembles

the svecofennian orogen a tectonic model abstract recent geological studies have provided new concepts concerning the timing of the final break up of the archaean craton age data on detrital zircons from sedimentary rocks in sweden and finland show marked similarities and indicate pervasive homogenization of accumulated material geochemical and isotopic studies in sweden and finland suggest the existence of two volcanic belts separated by an area dominated by sedimentary rocks however the ages of metamorphism and plutonism differ in particular the late post 1 85 ga granitoid magmatism was more voluminous in sweden than in finland the svecofennian crust in finland is anomalously thick up to 65 km and is characterized by a high velocity lower crust of variable thickness the evolution of the svecofennian orogen is modelled by opening of the pre svecofennian ocean at 1 95 ga and progressive accretion of two arc complexes to the archaean craton between 1 91 1 87 ga initial accretion at 1 91 ga led to thrusting of the slices of an island arc complex and proterozoic marine strata onto the thickening craton margin subduction reversal with simultaneous anti clockwise rotation of the converging plate or convergence of another plate resulted in subduction below the newly accreted arc complex the tectonic style at the craton margin changed from thrusting to lateral displacement in the east in finland in the west in sweden the subduction zone retreated along a transform fault a large sedimentary basin closed in the east 1 89 ga ago when another arc complex collided against the accreted one collision resulted in lithospheric thickening subsequent delamination of the thickened lithosphere and compensation by a hot mantle underplate and large scale granitoid magmatism as a result of mixing between mantle magma and remelted arc complex material the thick dense layer that formed in the lower crust as the result of underplating kept the thickened crust in isostatic balance thus the exhumation rate in this area was similar to the rate in areas of thinner crust subduction and sediment accumulation continued in the west until at least 1 87 ga when large areas in the east were already stabilized an intracratonic transpressional zone developed as the result of continued convergence subsequent extensional collapse along the transpressional zone caused melting of svecofennian sedimentary rocks migmatization and generation of the 1 84 1 82 ga anatectic granites of southern finland and central sweden the voluminous post 1 85 ga granitoid magmatism in sweden is tentatively associated with an east west extension that is not related to the extensional collapse

a proposed mechanism for the asymmetric duration of el nino and la nina el nino and la nina exhibit significant asymmetry not only in their spatial structure but also in their duration most el ninos terminate rapidly after maturing near the end of the calendar year whereas many la ninas persist into the following year and often reintensify in boreal winter through atmospheric general circulation model experiments it is shown that the nonlinear response of atmospheric deep convection to the polarity of equatorial pacific sea surface temperature anomalies causes an asymmetric evolution of surface wind anomalies over the far western pacific around the mature phase of el nino and la nina because of the eastward displacement of precipitation anomalies in the equatorial pacific during el nino compared to la nina surface winds in the western pacific are more affected by sst forcing outside the equatorial pacific which acts to terminate the pacific event

el nino east asian monsoon teleconnection and its diversity in cmip5 models in this study we assess the performance of state of the art coupled models in reproducing el nino diversity and its impacts on the east asian summer monsoon easm based on simulations taken from the coupled model intercomparison project phase 5 cmip5 all of the 17 models used in this study are identified to give reasonable eastern pacific ep el nino related sea surface temperature anomalies ssta and anomalous walker circulation compared with observations whereas one third of the models fail to reproduce the walker circulation anomalies for central pacific cp el nino in these models negative ssta over the eastern to central pacific are found to be too strong while positive ssta shift to the western pacific during cp el nino there is thus sinking rising motion over the central western part of the pacific basin implying westward displaced anomalous walker cells relative to the observed this results in simulated low level cyclonic flow and positive rainfall anomalies over the far western north pacific south china sea during and after the peak phase of cp el nino which are opposite to the observed anomalous climate state the other two thirds of models with realistic cp el nino related anomalous walker cell can better reproduce the corresponding wind circulation and rainfall anomalies over east asian ea region the contrasting cp el nino related teleconnection among models mainly arises from the different simulated cp el nino ssta which in turn determine the circulation anomalies through a gill type response further analyses reveal that in the mean state of models with erroneous teleconnection there exists a large cold sst bias over the eastern pacific the stronger walker circulation and possibly the stronger bjerknes feedback might be responsible for the overly negative ssta associated with cp el nino in the vicinity our results highlight the sensitivity of el nino ea climate linkage to the oceanic state in models especially for cp el nino events

correlation of carbon dioxide abundance with temperature in clastic hydrocarbon reservoirs relationship to inorganic chemical equilibrium the mol co2 of gas reservoired in sandstones tends to increase with increasing temperature along both the us gulf coast and the norwegian continental shelf each of these provinces displays identical linear correlations between temperature and the log of the partial pressure of co2 i e pco2 in the reservoir fluid that is the product of the mol co2 the reservoir pressure this correlation is the same both in gulf coast reservoirs younger than 17 ma and in norwegian reservoirs of jurassic to triassic age 144 245 ma indicating that it is not dependent on reaction kinetics norwegian shelf data indicate that the same correlation also applies for gas condensate and oil reservoirs we suggest that the log pco2versus temperature correlation is the result of inorganic chemical equilibria between feldspar clay and carbonate minerals a trend of decreasing ph with increasing temperature is fixed by equilibria between aluminosilicate minerals feldspar kaolinite at lower temperatures followed by various reactions between kaolinite illite chlorite and feldspar as temperatures exceed 110 140 c responding to the ph set by the aluminosilicate system co2 activity in the formation water and thereby co2 partial pressure in any gas phase present is controlled by equilibrium with carbonate minerals this model predicts that co2 released by organic maturation will in general result in precipitation of carbonate minerals below 100 120 c and that there should be widespread carbonate dissolution at higher temperatures

asymmetry in zonal phase propagation of enso sea surface temperature anomalies 1 it is often emphasized in the literature that the phase propagation of el nino sea surface temperature sst anomalies along the equator changed from westward to eastward after a mid to late 1970s climate regime shift in the pacific theories have been developed to explain this change of phase propagation in terms of changes in background state on which el nino events develop those theories also suggest that the direction of la nina anomaly phase propagation should have changed from westward to eastward as well however the direction of la nina sst anomaly phase propagation did not change after the mid to late 1970s instead la nina ssts continued to exhibit westward phase propagation along the equator a feature overlooked in both observational analyses and theories this paper highlights the asymmetry in zonal phase propagation between el nino and la nina sea surface temperature anomalies since 1980 and discusses the implications of that asymmetry for understanding el nino southern oscillation enso dynamics

el nino and la nina sea surface temperature anomalies asymmetry characteristics associated with their wind stress anomalies 1 the asymmetric nature of el nino and la nina sea surface temperature sst anomalies is investigated by the use of national centers for environmental prediction reanalysis data and various ocean and atmosphere models it is demonstrated that the relatively weak sst anomalies during la nina compared with those of el nino are related to the westward shift of wind stress anomalies by 10 15 the asymmetric characteristics of atmospheric responses are confirmed by the general circulation model experiments with the two different sst anomalies which have equal amplitude but are of opposite sign from each other the experiments with an intermediate ocean model and a hybrid coupled model clearly show that the sst anomalies over the equatorial pacific become weaker as the zonal wind stress shifts to the west not only the amplitude but also the oscillation timescale of the sst anomaly is shown to be sensitive to the location of wind stress anomalies the duration of la nina which is rather shorter than that of el nino is also related to the longitudinal displacement of the wind stress anomaly

investigating the role of the tibetan plateau in enso variability abstractthe role of the tibetan plateau tp in el nino southern oscillation enso variability is investigated using coupled model experiments with different topography setups removing the tp res

vertical structure variability and equatorial waves during central pacific and eastern pacific el ninos in a coupled general circulation model recent studies report that two types of el nino events have been observed one is the cold tongue el nino or eastern pacific el nino ep el nino which is characterized by relatively large sea surface temperature sst anomalies in the eastern pacific and the other is the warm pool el nino a k a central pacific el nino cp el nino or el nino modoki in which sst anomalies are confined to the central pacific here the vertical structure variability of the periods during ep and cp is investigated based on the gfdl cm2 1 model in order to explain the difference in equatorial wave dynamics and associated negative feedback mechanisms it is shown that the mean stratification in the vicinity of the thermocline of the central pacific is reduced during cp el nino which favours the contribution of the gravest baroclinic mode relatively to the higher order slower baroclinic mode energetic kelvin and first meridional rossby wave are evidenced during the cp el nino with distinctive amplitude and propagating characteristics according to their vertical structure mostly first and second baroclinic modes in particular the first baroclinic mode during cp el nino is associated to the ocean basin mode and participates to the recharge process during the whole el nino cycle whereas the second baroclinic mode is mostly driving the discharge process through the delayed oscillator mechanism this may explain that the phase transition from warm to neutral cold conditions during the cp el nino is delayed and or disrupted compared to the ep el nino our results have implications for the interpretation of the variability during periods of high cp el nino occurrence like the last decade

oceanic rossby wave dynamics and the enso period in a coupled model abstract tropical ocean wave dynamics associated with the el nino southern oscillation cycle in a coupled model are examined the ocean atmosphere model consists of statistical atmosphere coupled to a simple reduced gravity model of the tropical pacific ocean the statistical atmosphere is simple enough to allow for the structure and position of the wind stress anomalies to be externally specified in a control simulation where the structure of the wind stress anomaly is determined from observations the model produces a regular 5 yr oscillation this simulation is consistent with the so called delayed oscillator theory in that subsurface wave dynamics determine the slow timescale of the oscillation and surface layer processes are found to be of secondary importance kelvin and rossby wave propagation is detected along the equator with periods considerably shorter than the simulated oscillation period the way in which these relatively fast waves are related to the simulated 5 yr oscillation is discusse

kinetics of the smectite to illite transformation in the denver basin clay mineral k ar data and mathematical model results clay mineral data potassium argon k ar ages and mathematical model simulations indicate the important kinetic factors controlling the smectite to illite transformation illitization in upper cretaceous mowry and niobrara core and outcrop bentonites from the denver basin the data also provide additional information on the thermal history of the basin data show that both the percentages of illite layers and the k ar ages of mixed layer illite smectite i s increase with increasing depths of burial and this trend was simulated mathematically employing a very simplified burial model with a fifth order overall kinetic expression for the formation of illite for most of the basin the data is compatible with i s having been formed in response to increased temperature from progressive burial because the oldest k ar ages of i s are from the deepest buried i s along the basin axis in addition these data qualitatively suggest that i s even as small as 0 1 micrometer retains radiogenic argon under denver basin burial temperatures i s separated from drill core bentonites from the wattenberg gas field astride the basin axis and known to have been subjected to an anomalously high temperature history are the most illitic and among the oldest measured from core in this study the ages of illitization about 60 ma are coincident with the laramide time of structural development of the basin and uplift of the front range the reconstructions of the burial history and the modelling of the timing and extent of illitization suggest that the area of the wattenberg gas field was an upper cretaceous depocenter an area of relatively deeper burial along the basin axis however the data can not rule out the possibility that these sediments at and near the wattenberg gas field were heated not only by burial but also by i neous and related hydrothermal activity associated with the colorado mineral belt during the laramide uplift 70 45 ma of the front range likewise the anomalously illitic i s in outcrop bentonites along the front range adjacent to the wattenberg gas field may have been formed in response either to deep burial and or by laramide age secondary heating superimposed on burial

two leading enso modes and el nino types in the zebiak cane model abstractmodern instrumental records reveal that el nino events differ in their spatial patterns and temporal evolutions attempts have been made to categorize them roughly into two main types eastern pacific ep or cold tongue and central pacific cp or warm pool el nino events in this study we use a modified version of zebiak cane mzc coupled model to examine the dynamics of these two types of el nino events we conducted linear eigen analysis of the model to show that there are two leading enso el nino southern oscillation modes with their sst patterns resembling those of two types of el nino thus we refer them as the ep and cp enso modes these two modes sensitively depend on the changes in the mean states the heat budget analyses demonstrate that the ep cp mode is dominated by thermocline zonal advective feedback therefore weak strong mean wind stress and deep shallow mean thermocline prefers the ep cp enso mode because of the relatively dominance of thermocline zonal advect

meridional movement of wind anomalies during enso events and their role in event termination 1 observational analysis has shown that when el nino southern oscillation enso events typically reach their peak amplitude in boreal winter the associated zonal wind anomalies abruptly shift southward so that the maximum anomalous zonal wind is located around 5 7 s here an analysis utilizing multiple wind products identifies a clear enso phase nonlinearity in the extent of this meridional wind movement and its dynamically linked changes in equatorial heat content it is shown that the meridional wind movement and its discharging effect increase with increasing el nino amplitude while both remain relatively small regardless of la nina amplitude this result implies that asymmetries in the extent of the meridional wind shift may contribute to the observed asymmetry in the duration of el nino and la nina events we also evaluate the result sensitivities to wind product selection and discuss eastern pacific ep and central pacific cp el nino event differences

cold tongue and warm pool enso events in cmip5 mean state and future projections abstractthe representation of the el nino southern oscillation enso under historical forcing and future projections is analyzed in 34 models from the coupled model intercomparison project phase 5 cmip5 most models realistically simulate the observed intensity and location of maximum sea surface temperature sst anomalies during enso events however there exist systematic biases in the westward extent of enso related sst anomalies driven by unrealistic westward displacement and enhancement of the equatorial wind stress in the western pacific almost all cmip5 models capture the observed asymmetry in magnitude between the warm and cold events i e el ninos are stronger than la ninas and between the two types of el ninos that is cold tongue ct el ninos are stronger than warm pool wp el ninos however most models fail to reproduce the asymmetry between the two types of la ninas with ct stronger than wp events which is opposite to observations most models capture the observed peak in enso

causes of the el nino and la nina amplitude asymmetry in the equatorial eastern pacific abstract the amplitude asymmetry between el nino and la nina is investigated by diagnosing the mixed layer heat budget during the enso developing phase by using the three ocean assimilation products simple ocean data assimilation soda 2 0 2 soda 1 4 2 and the global ocean data assimilation system godas it is found that the nonlinear zonal and meridional ocean temperature advections are essential to cause the asymmetry in the far eastern pacific whereas the vertical nonlinear advection has the opposite effect the zonal current anomaly is dominated by the geostrophic current in association with the thermocline depth variation the meridional current anomaly is primarily attributed to the ekman current driven by wind stress forcing the resulting induced anomalous horizontal currents lead to warm nonlinear advection during both el nino and la nina episodes and thus strengthen weaken the el nino la nina amplitude the convergence divergence of the anomalous geostrophic mixed layer currents dur

re os ages for archean molybdenite and pyrite kuittila kivisuo finland and proterozoic molybdenite kabeliai lithuania testing the chronometer in a metamorphic and metasomatic setting seven 187re 187os ages were determined for molybdenite and pyrite samples from two well dated precambrian intrusions in fennoscandia to examine the sustainability of the re os chronometer in a metamorphic and metasomatic setting using a new 187re decay constant 1 666 10 11y 1 with a much improved uncertainty 0 31 we determined replicate re os ages for molybdenite and pyrite from the kuittila and kivisuo prospects in easternmost finland and for molybdenite from the kabeliai prospect in southernmost lithuania these two localities contain some of the oldest and youngest plutonic activity in fennoscandia and are associated with newly discovered economic au mineralization ilomantsi finland and a cu mo prospect kabeliai lithuania two re os ages for vein hosted kabeliai molybdenite average 1486 5 ma in excellent agreement with a 1505 11 ma u pb zircon age for the hosting kabeliai granite pluton the slightly younger age suggests the introduction of cu mo mineralization by a later phase of the kabeliai magmatic system mean re os ages of 2778 8 ma and 2781 8 ma for kuittila and kivisuo molybdenites respectively are in reasonable agreement with a 2753 5 ma weighted mean u pb zircon age for hosting kuittila tonalite these re os ages agree well with less precise ages of 2789 290 ma for a rb sr whole rock isochron and 2771 75 ma for the average of six sm nd tdm model ages for kuittila tonalite three re os analyses of a single pyrite mineral separate from the same sample of kuittila pluton that yielded a molybdenite separate provide individual model ages of 2710 27 2777 28 and 2830 28 ma re 17 4 12 1 and 8 4 ppb respectively with a mean value of 2770 120 ma in agreement with the kuittila molybdenite age the re and 187os abundances in these three pyrite splits are highly correlated r 0 9994 and provide a 187re 187os isochron age of 2607 47 ma with an intercept of 21 ppt 187os mswd 1 1 it appears that the re os isotopic system in pyrite has been reset on the millimeter scale and that the 21 ppt 187os intercept reflects the in situ decay of 187re during the 160 to 170 m y interval from 2778 ma time of molybdenite pyrite deposition to 2607 ma time of pyrite resetting when the re os data for molybdenites from the nearby kivisuo prospect are plotted together with the kuittila molybdenite and pyrite data a well constrained five point isochron with an age of 2780 8 ma and a 187os intercept 2 4 3 8 ppt of essentially zero results mswd 1 5 we suggest that the pyrite isochron age records a regional metamorphic and or hydrothermal event possibly the time of au mineralization a proposed re os age of 2607 ma for au mineralization is in good agreement with radiometric ages by other methods that address the timing of archean au mineralization in deposits worldwide so called late au model molybdenite in contrast provides a robust re os chronometer retaining its original formation age of 2780 ma despite subsequent metamorphic disturbances in archean and proterozoic time

significance of 1 5 ga zircon and monazite ages from charnockites in southern lithuania and ne poland abstract the presence of 1 52 1 50 ga charnockites from the anorthosite mangerite charnockite granite amcg mazury complex in southern lithuania and ne poland in the western east european craton eec is revealed by secondary ion mass spectrometry sims and epma geochronology early 1 85 1 82 ga charnockites are related to major orogeny in the region whereas the newly studied charnockites intrude the already consolidated crust the 1 52 1 50 ga charnockite magmatism sims data on zircon was followed by high grade metamorphism epma data on monazite which strongly affected the surrounding rocks the 1 85 1 81 ga zircon cores in lazdijai and 1 81 ga monazite domains in the lanowicze charnockites represent the protolith age of a volcanic island arc the 1 52 1 50 ga charnockite magmatism and metamorphism are likely related to the distal danopolonian orogeny further to the west at the margin of baltica the c 1 52 1 50 ga amcg magmatism and metamorphism in the western eec as well as the paired accretionary rapakivi suites in amazonia may be the inboard manifestations of the same early mesoproterozoic orogeny associated with the juxtaposition of amazonia and baltica during the amalgamation of the supercontinent columbia

two types of el nino events cold tongue el nino and warm pool el nino abstract in this study two types of el nino events are classified based on spatial patterns of the sea surface temperature sst anomaly one is the cold tongue ct el nino which can be regarded as the conventional el nino and the other the warm pool wp el nino the ct el nino is characterized by relatively large sst anomalies in the nino 3 region 5 s 5 n 150 90 w while the wp el nino is associated with sst anomalies mostly confined to the nino 4 region 5 s 5 n 160 e 150 w in addition spatial patterns of many atmospheric and oceanic variables are also distinctively different for the two types of el nino events furthermore the difference in the transition mechanism between the two types of el nino is clearly identified that is the discharge process of the equatorial heat content associated with the wp el nino is not efficient owing to the spatial structure of sst anomaly as a result it cannot trigger a cold event it is also demonstrated that zonal advective feedback i e zonal adve

palaeoproterozoic upb zircon ages from belorussia new geodynamic implications for the east european craton abstract the crust in the northwest of the east european craton has traditionally been regarded as part of an archaean nucleus in eastern europe recent correlation with the baltic shield in scandinavia however suggests the need of reappraisal to study this problem zircons from three boreholes in the basement of the russian platform in belorussia belarus have been dated by the u pb and pb pb methods the ages indicated by two u pb discordias are 1982 26 ma for a metadacite from the central belorussian belt of volcanic arc igneous rocks and 1800 7 ma for mafic granulite from the baltic belorussian granulite belt largely built up of mafic igneous rocks for another central belorussian metadacite a pb pb age of 1975 10 ma was obtained in previous stratigraphies of belorussia all three dated rocks have been considered to be important components of an archaean even early archaean crust analyses of abraded crystal cores of complex zircons in one sample and separated core and rim zircons in another do not suggest substantially older ages of the core materials together with previous ages of granitoids and charnockites which had however been explained as a result of late magmatism and metamorphism and therefore not characterizing the age of the crust our data indicate the dominance of palaeoproterozoic rocks in the basement of the northwestern part of the east european craton that adjoins the tornquist line boundary between central and northeastern europe in conjunction with the results of a finnish estonian study of similarly allegedly archaean but in actual fact proterozoic rocks in southern estonia our results suggest the existence of large palaeoproterozoic crustal belts extending all the way from the finnish gulf to eastern poland this implies a substantial revision of established concepts on the precambrian geology in the northeastern half of the european continent

understanding the double peaked el nino in coupled gcms coupled general circulation models cgcms simulate a diverse range of el nino southern oscillation behaviors double peaked el nino events where two separate centers of positive sea surface temperature sst anomalies evolve concurrently in the eastern and western equatorial pacific have been evidenced in coupled model intercomparison project version 5 cgcms and are without precedent in observations the characteristic cgcm double peaked el nino may be mistaken for a central pacific warming event in el nino composites shifted westwards due to the cold tongue bias in results from the australian community climate and earth system simulator coupled model we find that the western pacific warm peak of the double peaked el nino event emerges due to an excessive westward extension of the climatological cold tongue displacing the region of strong zonal sst gradients towards the west pacific a coincident westward shift in the zonal current anomalies reinforces the western peak in sst anomalies leading to a zonal separation between the warming effect of zonal advection in the west pacific and that of vertical advection in the east pacific meridional advection and net surface heat fluxes further drive growth of the western pacific warm peak our results demonstrate that understanding historical cgcm el nino behaviors is a necessary precursor to interpreting projections of future cgcm el nino behaviors such as changes in the frequency of eastern pacific el nino events under global warming scenarios

high resolution 3d seismic model of the crustal and uppermost mantle structure in poland abstract in the area of poland a contact between the precambrian and phanerozoic europe and the carpathians has a complicated structure and a complex p wave velocity of the sedimentary cover crystalline crust moho depth and the uppermost mantle the geometry of the uppermost several kilometers of sediments is relatively well recognized from over 100 000 boreholes the vertical seismic profiling vsp from 1188 boreholes provided detailed velocity data for regional tectonic units and for stratigraphic successions from permian to the tertiary and quaternary deposits these data however do not provide information about the velocity and basement depth in the central part of the trans european suture zone tesz and in the carpathians so the data set is supplemented by 2d velocity models from 32 deep seismic sounding refraction profiles which also provide information about the crust and uppermost mantle together with the results of other methods vertical seismic profiling magnetotelluric allow for the creation of a detailed high resolution 3d model for the entire earth s crust and the uppermost mantle down to a depth of 60 km the thinnest sedimentary cover in the mazury belarus anteclise is only 0 3 to 1 km thick which increases to 7 to 8 km along the east european craton eec margin and 9 to 12 km in the tesz the variscan domain is characterized by a 1 4 km thick sedimentary cover while the carpathians are characterized by very thick sedimentary layers up to about 20 km the crystalline crust is differentiated and has a layered structure the crust beneath the west european platform wep variscan domain is characterized by p wave velocities of 5 8 6 6 km s the upper and middle crusts beneath the eec are characterized by velocities of 6 1 6 6 km s and are underlain by a high velocity lower crust with a velocity of about 7 km s a general decrease in velocity is observed from the older to the younger tectonic domains the tesz is associated with a steep dip in the moho depth from 30 35 km in the paleozoic platform to 42 52 km in the precambrian craton the new model confirms the moho depth derived from previous compilations in the tesz the lower crust has a very high seismic velocity 7 0 km s which correlates to the high p wave velocity about 8 4 km s in the uppermost mantle beneath the polish basin the cratonic area is generally characterized by high p wave velocities 8 2 km s while the phanerozoic area is characterized by velocities of 8 0 km s in the tesz very high velocities of 8 3 8 4 km s are observed and the southwestern limitation of this area coincides with a high velocity lower crust and could be continued to the nw toward the elbe line the influence of the structure for teleseismic tomography time residuals of seismic waves traveling through the 3d seismic model was analyzed lithological candidates for the crust and uppermost mantle of the eec and wep were suggested by comparison to laboratory data the presented 3d seismic model may make more reliable studies on global dynamics and geotectonic correlations particularly for sedimentary basins in the polish lowlands the napped flysch sediment series in the carpathians the basement shape the southwestern edge of the eec a high velocity lower crust and the high velocity uppermost mantle in the tesz finally the new 3d velocity model of the crust shows a heterogeneous structure and offers a starting point for the numerical modeling of deeper structures by allowing for a correction of the crustal effects in studies of the mantle heterogeneities

age and tectonic framework of structurally controlled palaeoproterozoic gold mineralization in the hame belt of southern finland abstract a number of gold occurrences in the palaeoproterozoic svecofennian domain of southern finland show a clear structural control on mineralization and are classified as orogenic gold samples of pre syn and late to post mineralization rocks taken from two gold prospects in the somero tammela gold zone of the hame belt have been studied to gain absolute ages of mineralization by using sims u pb of zircon and titanite and ar ar single grain step heating of hornblende and biotite gold mineralization in the somero tammela gold zone is closely related to quartz veins and controlled by wsw ene to sw ne trending shear zones and faults formed during prolonged dextral oblique contraction in the late stages of svecofennian orogenic evolution zircons from a felsic volcanic host rock give an age of 1881 3 ma interpreted as the crystallization age of the rock and providing a maximum age for mineralization inherited zircons in a gold bearing quartz vein with the youngest zircon rim of 1832 15 ma give a maximum age of quartz vein emplacement a 1786 7 ma mean 207pb 206pb age of a pegmatitic quartz feldspar dyke providing a minimum age for mineralization is interpreted as reflecting lead loss whereas an 1815 4 ma zircon age is probably closer to the crystallization age of the dyke this age overlaps with 1805 4 5 4 ma 39ar 40ar age of hornblende from a quartz vein 1 78 and 1 76 ga 39ar 40ar biotite cooling ages mark the minimum age for mineralization in summary the age of mineralization can be estimated at ca 1 82 1 79 ga which is in good agreement with the age of dextral shearing in southern finland the controlling structures wsw ene to sw ne dextral shear zones and nw se oriented faults formed during approximately wnw ese oriented sub horizontal shortening during crossing ductile brittle boundary conditions the steep shear zones and faults and the intersection lines of the two sets impart a directional permeability allowing channelling of the mineralizing fluids in these structures this was supported by prolonged dextral oblique contraction enabling continuous or episodic slip along the faults and shear zones the late svecofennian tectonic episode could be described as an extension contraction cycle in a convergent plate margin setting above a retreating subduction zone oblique extension 1 86 1 83 ga caused by slab rollback was followed by a rapid switch to oblique contraction at ca 1 82 ga induced by arrival of positively buoyant crustal fragments e g oceanic ridge oceanic plateau or continental sliver at the subduction zone the contractional period characterized by dextral transpression provided a favourable setting for orogenic gold mineralization the termination of the svecofennian orogenic evolution in finland after 1 79 ga might be caused by lock up of the subduction zone and slab break off the striking nw se alignment of orogenic type gold occurrences in the svecofennian domain of southern finland suggests that the late svecofennian 1 82 1 79 ga gold mineralizing event may be regionally more widespread and of greater importance than hitherto expected

el nino modoki and its possible teleconnection 1 using observed data sets mainly for the period 1979 2005 we find that anomalous warming events different from conventional el nino events occur in the central equatorial pacific this unique warming in the central equatorial pacific associated with a horseshoe pattern is flanked by a colder sea surface temperature anomaly ssta on both sides along the equator empirical orthogonal function eof analysis of monthly tropical pacific ssta shows that these events are represented by the second mode that explains 12 of the variance since a majority of such events are not part of el nino evolution the phenomenon is named as el nino modoki pseudo el nino modoki is a classical japanese word which means a similar but different thing the el nino modoki involves ocean atmosphere coupled processes which include a unique tripolar sea level pressure pattern during the evolution analogous to the southern oscillation in the case of el nino hence the total entity is named as el nino southern oscillation enso modoki the enso modoki events significantly influence the temperature and precipitation over many parts of the globe depending on the season the impacts over regions such as the far east including japan new zealand western coast of united states etc are opposite to those of the conventional enso the difference maps between the two periods of 1979 2004 and 1958 1978 for various oceanic atmospheric variables suggest that the recent weakening of equatorial easterlies related to weakened zonal sea surface temperature gradient led to more flattening of the thermocline this appears to be a cause of more frequent and persistent occurrence of the enso modoki event during recent decades

contrasting the termination of moderate and extreme el nino events in coupled general circulation models as in the observed record the termination of el nino in the coupled ipcc ar4 climate models involves meridional processes tied to the seasonal cycle these meridional processes both precondition the termination of el nino events in general and lead to a peculiar termination of extreme el nino events such as those of 1982 83 and 1997 98 in which the eastern equatorial pacific warm sea surface temperature anomalies ssta persist well into boreal spring early summer the mechanisms controlling the peculiar termination of extreme el nino events which involves to the development of an equatorially centred intertropical convergence zone are consistent across the four models that exhibit extreme el ninos and observational record suggesting that this peculiar termination represents a general feature of extreme el ninos further due to their unusual termination extreme el ninos exhibit an apparent eastward propagation of their ssta which can strongly influence estimates of the apparent propagation of enso over multi decadal periods interpreting these propagation changes as evidence of changes in the underlying dynamical feedbacks behind el nino could therefore be misleading given the strong influence of a single extreme event

interannual variability of the north pacific mixed layer associated with the spring tibetan plateau thermal forcing abstractby using multisourced data and two sets of sensitivity runs from the coupled general circulation model cesm1 2 0 we investigated the effects of the spring march april and may mam sur

paleoproterozoic lateritic paleosol ultra mature mature quartzite meta arkose successions in southern fennoscandia intra orogenic stage during the svecofennian orogeny abstract a paleoproterozoic lateritic paleosol overlain by ultra mature mature quartzite is reported for the first time from three localities in the svecofennian province in southern finland these are important indicators for warm paleoclimate and continental paleoenvironment ultra mature quartzites above the lateritic paleosols are overlain by matrix supported conglomerates followed by mature quartzites these latter rocks are related to incipient rifting followed by main rift stage starting with increasingly more immature meta arkose we present a tectonic model in which exhumation after 1 88 1 87 ga contraction unroofed plutonic rocks volcanism and exhumation related erosion produced deposition of both volcanic and sedimentary material weathering of these rocks and deposition of ultra mature mature quartzites took place between 1 87 and 1 85 1 84 ga followed by rifting at 1 84 ga tectonic slicing during basin inversion thrust the pre rift quartzites and rift related volcanic and sedimentary rocks over older mid crustal rocks and produced a low angle stacking system to accommodate voluminous magmatism at deeper crustal levels and widespread sedimentation at the surface we propose that exhumation due to faulting followed by stabilization of the upper crust 0 15 20 km occurred simultaneously as the detached hot middle and lower crust experienced vertical shortening via ductile flow and extrusion the ca 1 85 ga paleosol quartzite successions in southern fennoscandia have many similarities with the widespread ca 1 7 ga paleosol quartzite successions in the united states both are intra orogenic formed on hot orogens and have simultaneous magmatism at deeper crustal levels and sedimentation at the surface accretion type models presented for southern fennoscandia at 1 87 1 80 ga are not compatible with the available data and either far field setting during outboard subduction or a newly formed continental interior setting are proposed anyhow tectonic models proposed for southern fennoscandia between 1 87 and 1 80 ga should take into account the occurrence of lateritic paleosols and ultra mature quartzites

basin scale evolution of formation waters a diagenetic and formation water study of the triassic chaunoy formation paris basin abstract formation waters and their movements within basins are commonly attributed with responsibility for patterns of cementation and porosity loss within reservoirs and aquifers it is thus important to understand when and how waters move in the subsurface we have studied the evolution and movement of formation water in the triassic chaunoy formation of the paris basin nw europe to define the way in which the water has evolved and to interpret water movement patterns using mineral isotope and fluid inclusion data in conjunction with detailed formation water analyses the chaunoy formation is cemented with different types of dolomite calcite and quartz cement we have studied the evolution of waters in terms of oxygen carbon and strontium isotopes and salinity connate waters were meteoric in origin but strongly influenced by the proximity of a playa lake input of palaeo meteoric water which entered the chaunoy via eastern halite bodies resulted in highly saline formation water for the majority of the chaunoy formation from about 100 ma until and for some time after maximum burial saline waters spread into the aquifer initially taking a west north west trajectory and then switching to a west south west pattern in the eocene following the alpine orogeny and localised uplift of the basin margin the southern portion of chaunoy received fresh low salinity meteoric water it is likely that formation water was lost from the chaunoy in a more central part of the basin via sub vertical cross formational flow to the mid jurassic dogger formation to accommodate the influx of fresh water

el nino la nina and the nonlinearity of their teleconnections the paradigm of an atmospheric system varying linearly with respect to extreme phases of the el nino southern oscillation is questioned it is argued that the global response to tropical pacific sea surface temperature forcing will be inherently nonlinear a physical basis for this intrinsic nonlinearity is the thermodynamic control on deep convection climate statistics for warm and cold events of the tropical pacific are analyzed separately for the northern winter periods during 1950 96 composite analysis of 500 mb heights reveal planetary scale teleconnection patterns as noted in earlier studies a new result is the evidence for an appreciable 358 longitude phase shift between the warm and cold event circulation composites and the two wave trains appear to have different tropical origins a large nonlinear component in north american surface climate anomalies is also found which is consistent with such a phase shift in teleconnections in the tropics rainfall anomalies also show evidence of nonlinear behavior the maximum rain anomalies along the equator are located east of the date line during warm events but west of the date line during cold events the interpretation of this behavior is complicated however by the fact that composite warm event sst anomalies are not the exact inverse of their cold event counterparts idealized atmospheric general circulation model agcm experiments are performed in order to test the question of whether the observed nonlinearity is an intrinsic property of the atmospheric system the model is forced with a composite sst anomaly that undergoes a realistic seasonally varying enso life cycle as described by e rasmusson and t carpenter both positive and negative phases of the sst anomaly are used and a 40 member ensemble of warm and cold event model simulations is conducted a nonlinear climate response in the agcm is found that closely resembles the observed composites including a shift in the equatorial positions of the maxmium rain responses and a phase shift of teleconnection patterns in the upper troposphere barotropic model experiments indicate that the inherent nonlinearity in the tropical rain response may itself be responsible for the phase shift in the extratropical teleconnection patterns

crustal structure of the trans european suture zone region along polonaise 97 seismic profile p4 1 the large scale polonaise 97 seismic experiment investigated the velocity structure of the crust and upper mantle in the trans european suture zone tesz region between the precambrian east european craton eec and paleozoic platform that comprises terranes added during the caledonian and variscan orogenies 530 370 and 370 225 ma respectively this experiment included 64 shots recorded by 613 seismic stations during two deployments very good quality data were recorded along five profiles and the longest and most important one p4 is the focus of this paper clear first arrivals and later phases of waves reflected refracted in the crust and moho were interpreted using two dimensional 2 d tomographic inversion and ray tracing techniques the crustal thickness along the profile varies from 30 35 km in the paleozoic platform area to 40 km below and due northeast of the tesz to 43 km in the polish part of the eec and to 50 km in lithuania the paleozoic platform and eec are divided by the polish basin so the upper crustal structure varies considerably in the area of the polish basin the p wave velocity is very low vp 6 1 km s down to depths of 15 20 km indicating that a very thick sedimentary sequence is present we suggest two possible tectonic interpretations of the velocity models 1 baltica indented avalonia obducting its upper crust and underthrusting its lower crust in a tectonic flake structure and 2 a rifted margin of baltica underlies the polish basin this model is similar to other interpretations of seismic profiles recorded in the baltic sea the second model implies that the paleozoic platform solely consists of avalonian lithosphere and the eec of baltica lithosphere it offers a simple explanation of the difference in crustal thickness of the two platforms it also implies that the caledonian and variscan orogenies in this area were relatively soft collisions that left this continental margin largely intact

enso regimes reinterpreting the canonical and modoki el nino 1 we propose that the first two empirical orthogonal function eof modes of tropical pacific sea surface temperature sst anomalies do not describe different phenomena i e el nino southern oscillation enso and el nino modoki but rather the nonlinear evolution of enso we introduce two new uncorrelated indices e and c based on the leading eofs that respectively account for extreme warm events in the eastern and cold moderate warm events in the central equatorial pacific corresponding to regimes with different evolution recent trends in enso can be described as an increase in the central pacific c variability that is associated with stronger cold events as well as a reduction in the eastern pacific e variability within the cold moderate warm regime consistent with model projections however little can be said observationally with respect to the extreme warm regime

the effect of the south pacific convergence zone on the termination of el nino events and the meridional asymmetry of enso abstractduring large el nino events the westerly wind response to the eastern equatorial pacific sea surface temperature anomalies sstas shifts southward during boreal winter and early spring reaching latitudes of 5 7 s the resulting meridional asymmetry along with a related seasonal weakening of wind anomalies on the equator are key elements in the termination of strong el nino events using an intermediate complexity atmosphere model it is demonstrated that these features result from a weakening of the climatological wind speeds south of the equator toward the end of the calendar year the reduced climatological wind speeds which are associated with the seasonal intensification of the south pacific convergence zone spcz lead to anomalous boundary layer ekman pumping and a reduced surface momentum damping of the combined boundary layer lower troposphere surface wind response to el nino this allows the associated zonal wind anomalies to shift south of the equator furthermore using a linear sh