grain size dependence of sediment composition and environmental bias in provenance studies abstract this article investigates both experimentally and theoretically the compositional changes associated with textural effects and hydraulic sorting during sediment transport and deposition which cause systematic distortion in quantitative provenance analysis environmental bias traditional procedures aimed at eliminating textural noise find limited success the gazzi dickinson method cannot remove hydrodynamic related modal variability multiple size window strategies are time consuming narrow or moving size window strategies represent misleading or impractical short cuts being less convenient options than simply analysing each sample in bulk new concepts introduced here unravel the superposed causes of compositional variability in modern sediments intrasample modal variability fundamentally explained by settling equivalence relationships can be accurately modelled mathematically intersample modal variability principally resulting from selective entrainment can be assessed and removed by a simple principle in absence of provenance changes and environmental bias the weighted average density of terrigenous grains srd index should be equal for each sample and each grain size class of each sample to the weighted average density of source rocks by correcting relative abundances of detrital minerals in proportion to their densities we can restore the appropriate srd index for any provenance and subprovenance type in each sample or grain size class modal variability is effectively reduced by this procedure which can be applied confidently to modern sediments deposited by tractive currents in any environment good results are obtained even for placer sands and finest classes where heavy mineral concentration is strongest such srd correction also successfully compensates for biased narrow window modes thus providing a numerical solution of general validity to the problem of environmental bias in sedimentary petrology after compensating for settling equivalence and selective entrainment effects residual size dependent compositional variability may be provenance related minor in ganga brahmaputra sediments provenance related effects are spectacularly displayed in the nile basin where volcaniclastic silt mixes with basement derived quartzofeldspathic sand and wind blown saharan quartz

making geological sense of big data in sedimentary provenance analysis abstract sedimentary provenance studies increasingly apply multiple chemical mineralogical and isotopic proxies to many samples the resulting datasets are often so large containing thousands of numerical values and complex comprising multiple dimensions that it is warranted to use the internet era term big data to describe them this paper introduces multidimensional scaling mds generalised procrustes analysis gpa and individual differences scaling indscal a type of 3 way mds algorithm as simple yet powerful tools to extract geological insights from big data in a provenance context using a dataset from the namib sand sea as a test case we show how mds can be used to visualise the similarities and differences between 16 fluvial and aeolian sand samples for five different provenance proxies resulting in five different configurations these configurations can be fed into a gpa algorithm which translates rotates scales and reflects them to extract a consensus view for all the data considered together alternatively the five proxies can be jointly analysed by indscal which fits the data with not one but two sets of coordinates the group configuration which strongly resembles the graphical output produced by gpa and the source weights which can be used to attach geological meaning to the group configuration for the namib study the three methods paint a detailed and self consistent picture of a sediment routing system in which sand composition is determined by the combination of provenance and hydraulic sorting effects

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

the cenozoic evolution of the roer valley rift system integrated at a european scale the roer valley rift system rvrs is located between the west european rift and the north sea rift system during the cenozoic the rvrs was characterized by several periods of subsidence and inversion which are linked to the evolution of the adjacent rift systems combination of subsidence analysis and results from the analysis of thickness distributions and fault systems allows the determination of the cenozoic evolution and quantification of the subsidence during the early paleocene the rvrs was inverted laramide phase the backstripping method shows that the rvrs was subsequently mainly affected by two periods of subsidence during the late paleocene and the oligocene quaternary time intervals separated by an inversion phase during the late eocene during the oligocene and miocene periods the thickness of the sediments and the distribution of the active faults reveal a radical rotation of the direction of extension by about 70 80j counter clockwise integration of these results at a european scale indicates that the late paleocene subsidence was related to the evolution of the north sea basins whereas the oligocene quaternary subsidence is connected to the west european rift evolution the distribution of the inverted provinces also shows that the early paleocene inversion laramide phase has affected the whole european crust whereas the late eocene inversion was restricted to the southern north sea basins and the channel area finally comparison of these deformations in the european crust with the evolution of the alpine chain suggests that the formation of the alps has controlled the evolution of the european crust since the beginning of the cenozoic

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

quantitative provenance analysis of sediments review and outlook provenance analysis of sediments is aimed at reconstructing the parent rock assemblages of sediments and the climaticphysiographic conditions under which sediments formed inferring sediment provenance from the final product a basin fill is anything but straightforward because the detrital spectrum evolves as the sediment is transported along the pathway from source to basin successful provenance analysis requires that the nature and extent of compositional and textural modifications to the detrital spectrum be recognised if not quantified the history of quantification in sediment provenance studies is summarised and illustrated by tracking two fundamental ideas the concept of the sediment petrological province or petrofacies and the relation between sandstone composition and plate tectonic environment progress in sedimentary provenance analysis has been closely linked with advancements in measurement technology a brief survey of modern data acquisition tools illustrates the possibilities and limitations of modern provenance research an operational definition of quantitative provenance analysis qpa is presented in which the central role of mass balance is acknowledged extension of this definition to include quantitative predictions obtained by forward modelling computer simulation of sediment production as well as methodological improvements in data acquisition and processing is needed to cover likely future developments in qpa the contributions to the special issue quantitative provenance analysis of sediments illustrate the intrinsic multidisciplinarity and rapid expansion of qpa d 2004 elsevier b v all rights reserved

the cenozoic lower rhine basin rifting sedimentation and cyclic stratigraphy in the cenozoic the lower rhine basin formed as a rift at the southeastern terminus of the dutch german central graben while the rhenish massif was uplifted the study focusses on the marginal marine and fluvial fill of the lower rhine basin a basin model is developed support for this study was given by extensive industry outcrop and well data by new stratigraphical and sedimentological observations the ingression and subsequent regression of the cenozoic north sea is analysed using the concept of base level cyclicity as the geohistory of the basin was complex a subsidence curve is constructed furthermore an attempt is made to trace the simultaneous uplift of the rhenish massif

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

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

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

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

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

from morphostratigraphy to geochronology on the dating of ice marginal positions abstract this study focuses on the glacial landscape of northern germany as a part of the southwestern sector of the scandinavian ice sheet sis as it has a research history reaching back about 130 years since the glacial theory replaced the drift theory in the late 19th century it has experienced a number of key changes including the introduction of the concept of polyglaciation or the differentiation of ice advances within one glaciation which is closely linked to the morphostratigraphical definition of ice marginal positions with the development of numerical dating methods the rather static morphostratigraphically based chronologies which are deeply rooted in research history have been confronted with a growing number of geochronometrical data obtained from glacigenic deposits in order to date ice marginal positions the two most commonly used dating methods for that purpose are optically stimulated luminescence osl and surface exposure dating of erratic boulders this study highlights the dependency of the significance of results from different dating methods on the sampling position within the geomorphological framework results from osl and surface exposure dating for the same ice marginal position in theory cannot be the same as the methods date different processes in the development of the glacial landscape osl dating of fluvioglacial sandur sediments dating the process of active sedimentation at the ice front and surface exposure dating of boulders on end moraines dating the process of stabilisation of end moraines after the retreat of the ice front often qualify as the most useful combination of techniques in order to define a time interval for the formation of the landforms at a specific ice marginal position methodological drawbacks which might occur unfortunately tend to widen the process induced offset between osl and surface exposure ages incomplete bleaching of fluvioglacial sediments might cause an offset towards a maximum osl age for an ice marginal position whereas delayed stabilisation or post exposure relocation of boulders might cause a shift towards a minimum age of key importance are the influence of periglacial processes and the effects of melting of buried ice on landform stabilisation which remain to be quantified a possible solution to this problem combining osl and surface exposure dating is suggested in this study nevertheless the possibility exists to date different geomorphological processes by applying different dating methods to glacigenic deposits this allows for a differentiated reflection of morphostratigraphically based chronologies against the background of the modern concept of dynamic ice sheets in contrast to the traditional morphostratigraphical definition of ice marginal positions a time based definition is proposed because it offers the possibility of a more detailed reconstruction of ice sheet dynamics at a certain point in time

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

from gullies to mountain belts a review of sediment budgets at various scales this paper reviews the state of the art in the concept as well as in the application of sediment budgets in sedimentary research sediments are a product of mass dispersal at the earth surface and take part in global cycles sediment budgets aim at quantifying this mass transfer based on the principle of mass conservation and are the key to determine ancient fluxes of solid matter at the earth surface this involves fundamental questions about the interplay of uplift climate and denudation in mountain belts and transfer of sediments from the continents to the oceans as well as applied issues such as soil and gully erosion reservoir siltation and coastal protection first after introducing basic concepts relevant scales and methodologies the different components of quaternary routing systems from erosion in headwaters river systems glacial and paraglacial systems lakes deltas estuaries coasts shelves epicontinental seas and deep sea fans are discussed in terms of their sediment budget most suitable are sedimentologically closed or semi closed depositional environments e g alluvial fans lakes deltas and deep sea fans in a second step the dynamics of passive active and collisional tectonic settings and sediment budgets in related sedimentary basins are explored and new concepts of sediment portioning at large geodynamic scales are introduced ancient routing systems are more or less incomplete and may be intensively fragmented or destroyed in active tectonic settings in terms of sedimentary basin types rifts intracontinental and epicontinental settings are preferred objects of sediment budgets because of their persistence and relatively simple overall sedimentary architecture however closing basins such as foreland forearc retroarc piggy back and wedge top basins may provide excellent snapshots of orogenic sediment fluxes in a third step the large long lived routing systems of the amazon the ganges brahmaputra and the rhine are reviewed for each system estimates of either sediment volumes mass or sediment fluxes of continental and marine subsystems have been compiled in order to receive a complete routing in terms of mass conservation for specific time periods since the late glacial maximum as well as the cenozoic following lessons can be taken from these case studies i depositional centers and fluxes show strong shifts in space and time and call for caution when simply looking at subsystems ii the response times of these large systems are within the milankovich time interval thus lower than predicted from diffusion models iii cyclic routing of sediments in continental basins is much more dominated by climate human control than by eustacy and iv at long time scales ultimate sinks win over intermittent storage it is concluded from this review that the quantitative understanding of global sediment cycling over historic and geologic time and its response to allogenic forcing is still in its infancy and further research is needed towards a holistic view of sediment routing systems at various temporal and spatial scales and their coupling with global biogeochemical cycles this includes i to better determine response times of large routing systems by linking quaternary with cenozoic sediment budgets and continental with marine sub systems ii to combine advanced provenance techniques with sediment budgets in order to reconstruct ancient systems iii to study sediment partitioning at the basin scale iv to reconcile continental supply dominated sequence stratigraphy with the eustatic dominated marine concept and iv to account for non actualism of ancient systems with respect to their erosion and transport mode in particular during glaciations and pronounced arid intervals glacial and eolian sediment routing may cross over hydrologic boundaries of drainage basins thus challenging the principle of mass conservation

workflow for analysis of compositional data in sedimentary petrology provenance changes in sedimentary basins from spatio temporal variation in heavy mineral assemblages the field of provenance analysis has seen a revival in the last decade as quantitative data acquisition techniques continue to develop in the 20th century many heavy mineral data were collected these data were mostly used as qualitative indications for stratigraphy and provenance and not incorporated in a quantitative provenance methodology even today such data are mostly only used in classic data tables or cumulative heavy mineral plots as a qualitative indication of variation the main obstacle to rigorous statistical analysis is the compositional nature of these data which makes them unfit for standard multivariate statistics to gain more information from legacy data a straightforward workflow for quantitative analysis of compositional datasets is provided first 1 a centred log ratio transformation of the data is carried out to fix the constant sum constraint and non negativity of the compositional data next 2 cluster analysis is followed by 3 principal component analysis and 4 bivariate log ratio plots several 5 proxies for the effects of sorting and weathering are included to check the provenance significance of observed variations and finally a 6 spatial interpolation of a provenance proxy extracted from the dataset can be carried out to test this methodology available heavy mineral data from the southern edge of the miocene north sea basin are analysed the results are compared with available information from literature and are used to gain improved insight into miocene sediment input variations in the study area

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

from static to dynamic provenance analysis sedimentary petrology upgraded abstract the classical approach to sandstone petrology established in the golden years of plate tectonics and based on the axiom that detrital modes of sandstone suites primarily reflect the different tectonic settings of provenance terranes has represented a benchmark for decades the composition of sand and sandstone however simply provides us with a distorted image of the lithological structure of source terranes and gives us little clue whether they are allochthonous or autochthonous orogenic or anorogenic young or old what we may able to see reflected in detrital modes is the nature of source terranes continental arc oceanic and the tectonostratigraphic level reached by erosion in space and time the proposed new approach to the petrology of sand and sandstone 1 starts with a simple classification scheme circulated since the 1960s which is purely descriptive objective and free of ill defined ambiguous terms and 2 focuses on the nature and tectonostratigraphic level of source terranes further steps are essential to upgrade provenance analysis acquiring knowledge from modern settings is needed to properly identify and wherever possible correct for physical and chemical processes introducing environmental and diagenetic bias and thus address nature s complexities with adequate conceptual tools equally important is the integration of multiple techniques ideally including bulk sediment multi mineral and single mineral methods bulk sediment petrography remains the fundamental approach that allows us to capture the most precious source of direct provenance information represented by the mineralogy and texture of rock fragments bulk sediment geochemistry applicable also to silt and clay carried in suspension is a superior method to check for hydraulic sorting chemical weathering and fertility of detrital minerals in different sediment sources detrital geochronology thermochronology and isotope geochemistry reveal the diverse time structures of source rocks and have become necessary complementary techniques in modern provenance analysis inferences on geodynamic processes need independent geological information and come last but if tackled properly they can lead us much farther than the standard label obtained by using triangular diagrams uncritically as if they were infallible oracles

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

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

garnet compositions in scottish and norwegian basement terrains a framework for interpretation of north sea sandstone provenance detrital garnets have proved to be useful discriminators of north sea sandstone provenance because they show a wide range of potential compositions and are relatively stable during burial diagenesis it has been less easy to use garnet data to provide a direct link between sediment and source because of the lack of a comprehensive database of garnet compositions in basement terrains forming the north sea hinterland this paper presents garnet compositional data from river sediments sourced from northern scotland and norway and demonstrates the presence of marked variations in garnet compositions from different regions related to fundamental differences in basement lithology the value of the river sediment database is demonstrated by comparing it with garnet compositions in paleocene sandstones from the north sea and more basins enabling the establishment of direct links between source and sediment paleocene sandstones in the gannet field area on the southwestern margin of the central north sea were derived from the dalradian of the grampian highlands those in the northern north sea were derived from the moine dalradian rocks of shetland and those along the more basin margin were derived from western norway by contrast paleocene sandstones in the nelson field central north sea and in the beryl embayment northern north sea have a garnet component that cannot be readily traced back to any basement terrain in either scotland or norway this component which was ultimately derived from granulite facies metasediments or charnockites is interpreted as being recycled from triassic sandstones which were themselves derived from an exotic source probably to the west of the british isles q 2004 elsevier ltd all rights reserved

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

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

shallow marine lower and middle miocene deposits at the southern margin of the north sea basin northern belgium dinoflagellate cyst biostratigraphy and depositional history detailed dinoflagellate cyst analysis of the lower middle miocene berchem formation at the southernmost margin of the north sea basin northern belgium allowed a precise biostratigraphical positioning and a reconstruction of the depositional history the two lower members of the formation edegem sands and decalcified kiel sands are biostratigraphically regarded as one unit since no significant break within the dinocyst assemblages is observed the base of this late or latest aquitanian burdigalian unit coincides with sequence boundary aq3 bur1 as defined by hardenbol and others in work published in 1998 a hiatus at the lower middle miocene transition separates the upper member the antwerpen sands from the underlying member the greater part of the antwerpen sands were deposited in a langhian latest burdigalian middle serravallian interval the base of this unit coincides with sequence boundary bur5 lan1 biostratigraphical correlation points to a diachronous post depositional decalcification within the formation since parts of the decalcified kiel sands can be correlated with parts of the calcareous fossil bearing section up to now interpreted as antwerpen sands the dinoflagellate cyst assemblages are dominated by species with a inner neritic preference although higher numbers of oceanic taxa in the upper part of the formation indicate incursions of oceanic watermasses into the confined depositional environment of the southern north sea basin

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

uses and misuses of compositional data in sedimentology this paper serves two goals the first part shows how mass evolution processes of different nature become undistinguishable once we take a size limited noisy sample of its compositional fingerprint processes of exponential decay mass mixture and complementary accumulation are simulated and then samples contaminated with noise are extracted the aim of this exercise is to illustrate the limitations of typical graphical representations and statistical methods when dealing with compositional data i e data in percentages concentrations or proportions the second part presents a series of concepts tools and methods to represent and statistically treat a compositional data set attending to these limitations the aim of this second part is to offer a state of the art compositional data analysis this includes descriptive statistics and graphics the biplot ternary diagrams with confidence regions for the mean regression and analysis of variance models to explain compositional variability and the use of compositional information to predict environmental covariables or discriminate between groups all these tools share a four step algorithm 1 transform compositions with an invertible log ratio transformation 2 apply a statistical method to the transformed scores 3 back transform the results to compositions and 4 interpret results in relative terms using these techniques a data set of sand petrographic composition has been analyzed highlighting that finer sands are richer in single crystal grains in relation to polycrystalline grains and that grain size accounts for almost all compositional variability a stronger water flow river discharge favors mica grains against quartz or rock fragment grains possibly due to hydrodynamic sorting effects a higher relief ratio implies shorter residence times which may favor survival of micas and rock fragments relatively more labile grains

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

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

european cenozoic rift system abstract the european cenozoic rift system extends from the coast of the north sea to the mediterranean over a distance of some 1100 km it finds its southern prolongation in the valencia trough and a plio pleistocene volcanic chain crossing the atlas ranges development of this mega rift was paralleled by orogenic activity in the alps and pyrenees major rift domes accompanied by subsidence reversal of their axial grabens developed 20 40 ma after beginning of rifting uplift of the rhenish shield is related to progressive thermal lithospheric thinning the vosges black forest and the massif central domes are probably underlain by asthenoliths emplaced at the crust mantle boundary evolution of this rift system is thought to be governed by the interaction of the eurasian and african plates and by early phases of a plate boundary reorganization that may lead to the break up of the present continent assembly

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

quantitative models of sediment generation and provenance state of the art and future developments abstract an overview of quantitative approaches to analysis and modelling of sediment generation and provenance is presented with an emphasis on major framework components as determined by means of petrographic techniques conceptual models of sediment provenance are shown to be consistent with two classes of numerical statistical models i e linear mixing models and compositional linear models these cannot be placed within a common mathematical framework because the former requires that sediment composition is expressed in terms of proportions whereas the latter requires that sediment composition is expressed in terms of log ratios of proportions additivity of proportions a fundamental assumption in linear mixing models cannot be readily expressed in log ratio terms linear mixing models may be used to describe compositional variability in terms of physical and conceptual un mixing models of physical un mixing are appropriate for describing compositional variation within transport invariant subpopulations of grains as a result of varying rates of supply of detritus from multiple sources conceptual un mixing governs the relations among chemical mineralogical and petrographic characteristics of sediments which represent different descriptive levels within a compositional hierarchy compositional linear process models may be used to describe compositional and or textural evolution resulting from selective modifications induced by sediment transport as well as chemical and mechanical weathering current approaches to modelling of surface processes treat the coupled evolution of source areas and sedimentary basins in terms of bulk mass transfer only and do not take into account compositional and textural sediment properties moving from the inverse modelling approach embodied in provenance research to process based forward models of sediment generation which provide detailed predictions of sediment properties meets with considerable albeit not insurmountable problems strategies for developing more advanced parameterizations of sediment properties and for simulating their evolution are proposed and expansion of current data acquisition protocols is discussed in the light of data requirements for such advanced sediment generation models inclusion of sediment generation modules in models of landscape evolution and basin filling will mark a significant step towards full fledged source to sink simulations of earth surface processes

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

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

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

varietal heavy mineral analysis of sediment provenance lower cretaceous scotian basin eastern canada abstract the origin of a major increase in sand supply in the early cretaceous of the scotian basin offshore eastern canada has been investigated by analysis of heavy mineral varieties the chemistry of detrital minerals from the scotian basin was compared with that of minerals from potential source rocks sampled from older sedimentary successions river sands and glacial tills on land heavy mineral varieties were established based on 1000 high quality electron microprobe emp analyses and used to classify heavy mineral types by mineral liberation analysis mla which uses a rapid scanning electron microscope particle analyser heavy mineral varieties were compared between the cretaceous quartz arenites and subarkoses and samples from potential source areas different chemical varieties of the same mineral group have different grain size distributions so that their relative modal abundances may be influenced by hydraulic sorting but modal abundance of different varieties of tourmaline garnet and spinel provides useful information widely used provenance sensitive mineral ratios are difficult to interpret because of the abundance of polycyclic sources comparisons of the shape parameters of the individual mineral types are also useful for provenance identification aspect ratio in elongate grains such as tourmaline and zircon is a measure of polycyclic reworking but is influenced by the initial shapes of minerals from different source rocks uniformity of varietal heavy minerals over a large area and stratigraphic range and the covariance of spinel and zircon with quite different crystalline sources indicate predominance of polycyclic sources to the central scotian basin probably principally from carboniferous and lower paleozoic sandstones in part sourced from western newfoundland ophiolites heavy mineral varieties in the west scotian basin can be closely matched to sources in the adjacent meguma terrane of the appalachians all the data show that the sands of the scotian basin were derived from reworking of crystalline basement of the appalachian orogen and its paleozoic sandstone cover uplifted during rifting of iberia from the grand banks there is no evidence of a significant supply of sand to the scotian basin from a proto st lawrence river

distinguishing fluvio deltaic facies by bulk geochemistry and heavy minerals an example from the miocene of denmark interpretations of seismic profiles gamma ray logs and sediment descriptions were used to classify seven facies in miocene fluvio deltaic deposits of denmark an impartial approach was adopted by not including analytical data in the facies definition this approach allowed identification of significant differences between facies where each fluvio deltaic facies can be distinguished by integrating geochemistry and mineralogy through a sedimentary succession variations in the heavy mineral assemblage between facies are caused primarily by sorting of hydraulically equivalent grains decreasing grain size of quartz and heavy minerals from the channel facies towards the delta shoreface facies and further along the coast to the spit shoreface facies is associated with an increase in sorting and textural maturity this trend is related to longshore drift increasing heavy mineral grain size is found from the delta slope facies offshore to the delta toe and shelf facies this trend is interpreted as a result of sorting by turbidity currents the mixed origin of the transgressive lag facies is shown by the poorer sorting in this facies by indicating the amount of alteration the sediments have been exposed to the ti mineral maturity has proven useful in characterizing the facies this systematic approach of tying depositional environments to a well calibrated sequence stratigraphic model has generated analytical results which are valid as reference levels for future facies identifications

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

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

erosion in the western alps dora baltea basin 1 quantifying sediment provenance abstract sourced in the m bianco the highest mountain of the alps the dora baltea river cuts across the arc of the western alps drains all major alpine tectonic units from the helvetic domain to the south alpine domain and finally joins the po river petrographic composition of clastic detritus carried by the dora baltea river and its tributaries faithfully mirrors the complex geology of the western alps high resolution modal analysis of dora baltea sands allowed us to distinguish seven end member metamorphoclastic provenances river sands from the m bianco external massif are dominated by quartz feldspars and hornblende detritus from basement and cover rocks of the brianconnais zone includes low grade metasedimentary lithic fragments epidote chloritoid and garnet sands from the internal penninic massifs include quartz and subordinate feldspars garnet and epidote abundant metabasite and serpentine schist lithic grains along with epidote actinolite and few pyroxenes characterize detritus from the calcschists and meta ophiolites of the oceanic piemonte zone sands from the austroalpine zone include quartz abundant metamorphic lithic fragments garnet and locally significant sillimanite dent blanche kinzigites the relative contribution of each end member to the dora baltea sediment flux was assessed with forward modelling of end member mixing our estimates calculated from the entire petrographic and mineralogical data set indicate that the main sources of bed load in the dora baltea mountain basin are the granitoid to gneissic rocks exposed in the m bianco massif and in the austroalpine zone in order to make allowance for the contribution of a particular bedrock constituent in a compound source area to the derivative sand the original concept of sand generation index sgi was modified to assess the relative contribution of the seven end member sources of detritus the highest total basin sgi indices are calculated for the m bianco massif sgi 16 4 and austroalpine domain sgi 1 4 the m bianco massif which represents only 3 of the whole catchment has the highest capacity of sand sized bed load production owing to its granitoid lithology and extreme relief this actualistic provenance study demonstrates that sediment composition can be markedly influenced by source rocks that occupy only a minor portion of the drainage area

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