climate reconstruction for the holsteinian interglacial in eastern poland and its comparison with isotopic data from marine isotope stage 11 abstract sediments of palaeolakes located in eastern poland represent the holsteinian interglacial and the initial part of the succeeding saalian glaciation they consist of 55 m thick lake marl and calcareous gyttja deposits reconstruction of climate during this part of the pleistocene was carried out by the analyses of oxygen and carbon isotope ratios of carbonates palynological data al and ca content of sediments isotope ratios and palynological results give in some cases contradictory results 18o ratios from lake ossowka eastern poland indicate relatively cool conditions at the climatic optimum of the holsteinian interglacial low ratios may have been caused by increased precipitation that led to high stands of the lake level during the initial stages of the following glaciation the 18o and 13c ratios increased probably resulting from low water level and strong evaporation in cool and dry climate phases additionally high al contents indicate high allochthonous siliciclastic input high ca concentrations indicate autochthonous carbonate precipitation from the lake epilimnion the combined climate indicators for the holsteinian interglacial in eastern poland suggest that this temperate episode corresponds to marine isotope stage 11 mis 11 of the north atlantic comparison of the continental record from eastern poland with the marine record from the north atlantic separated by about 2500 km indicates that even small climatic changes can be identified in genetically different deposits documenting the global nature of pleistocene climate trends

precise p and s wave velocity structures in the kitakami massif northern honshu japan from a seismic refraction experiment the kitakami massif which is located in the eastern part of northern honshu japan is composed of two geological units the northern kitakami terrane is characterized as a jurassic accretionary complex while the southern kitakami terrane consists of pre silurian basement and silurian lower cretaceous marine sediments the boundary region of these two units called the hayachine tectonic belt htb is composed of mafic to ultramafic rocks the kitakami massif experienced intense granitic intrusions in the cretaceous we present a detailed crustal structure model for the eastern part of the massif derived from an extensive seismic refraction experiment conducted on a 194 km n s line the uppermost crust is covered with a very thin 0 5 1 km surface layer with a velocity of 3 1 5 4 km s the velocity structure below this layer shows remarkable lateral variation in the northern kitakami terrane the p wave velocity and vp vs at the top of the basement are 5 85 5 95 km s and 1 68 1 70 respectively the seismic attenuation in this region is high qp 150 200 and qs 70 100 in contrast the uppermost crust in the southern kitakami terrane is characterized by a high p wave velocity 6 05 6 15 km s and vp vs 1 74 1 77 the qp and qs also show high values of 300 400 and 150 200 respectively such a structural difference persists to 14 to 16 km depth at which the p wave velocity increases to 6 45 km s the low velocity and high attenuation in the northern kitakami terrane represent a highly deformed structure of the accretionary complex the high p wave velocity and vp vs in the southern kitakami terrane indicate the relatively mafic crustal composition which may result from the fragment of the oceanic crust incorporated by the accretion process or the uplifting in the latest jurassic early cretaceous a midcrustal interface determined from wide angle reflections shows an abrupt southward depth decrease from 25 to 20 km under the htb the p wave velocity and vp vs between 14 and 16 km depth and the midcrustal interface are 6 45 6 55 km s and 1 74 1 78 respectively the moho depth under the northern kitakami terrane decreases southward from 34 to 32 km in the southern kitakami terrane the moho dips slightly southward the p wave velocity and the vp vs ratio in the lower crust are 6 9 7 0 km s and 1 75 1 76 respectively the p wave velocity in the uppermost mantle is not well resolved but is probably less than 7 7 km s the s wave velocity derived from relatively clear sn is 4 35 4 40 km s our results show that the htb is a prominent structural boundary extending to the moho the crust of kitakami massif was not homogenized by the cretaceous granitic intrusions and the original structural difference remains in the upper crust

crustal structure of the western new england appalachians and the adirondack mountains we present an interpretation of the crustal velocity structure of the new england appalachians and the adirondack mountains based on a seismic refraction wide angle reflection experiment in eastern north america extending from the adirondacks in new york state through the northern appalachians in vermont and new hampshire to central maine modeling of the eastern portion of the profile within the new england appalachians shows a subhorizontal layered crust with upper crustal velocities ranging from 5 5 to 6 2 km s a midcrustal velocity of 6 4 km s and a lower crustal velocity of approximately 6 8 km s crustal thickness increases from 36 km beneath maine to 40 km in vermont little evidence is seen for structures at depth directly related to the white mountains or the green mountains a major lateral velocity change in the upper and mid crust occurs between the appalachians and the adirondacks this boundary projecting to the surface beneath the champlain valley dips to the east beneath the green mountains and extends to a depth of 25 km below the eastern edge of the connecticut valley synclinorium in vermont the tahawus complex a series of strong horizontal reflections at 18 24 km depth beneath the adirondack highlands is seen to dip eastward beneath vermont upper crustal rocks in the adirondack mountains have poisson s ratios of 0 28 0 01 that can be correlated with the marcy anorthosite pois son s ratios of 0 24 0 01 calculated for rocks of the connecticut valley synclinorium indicate a siliceous upper crust in vermont the lower crust is considered to be best represented by intermediate to mafic granulites a high poisson s ratio 0 26 0 27 tends to support a mafic lower crust in the new england appalachians this seismic refraction wide angle reflection experiment provides further evidence for the obduction of the allochthonous western appalachian units onto grenvillian crust above a zone of detachment that penetrates at least to midcrustal depths and was the locus of successive paleozoic thrusting

holsteinian interglacial marine isotope stage 11 abstract the problem of correllating the holsteinian interglacial with the marine isotope stage mis is still disputed generally a view persists that this interglacial should be linked with mis 11 although this approach has many adversaries palynologic and geochemical data from well preserved fossil lake deposits from the holsteinian interglacial in eastern poland have enabled their correlation with mis 11

geophysical studies of the structure of the appalachian orogen in the atlantic borderlands of canada results of 6000 km of crustal seismic profiling are presented with gravity and aeromagnetic maps for the appalachian orogen in eastern canada wide angle seismic surveys show that the central mobile belt of the orogen has a thinner crust than its margins high velocity lower crust attributed to underplating is found below the former laurentian continental margin in newfoundland and below the magdalen basin potential field data are used to trace the surface zones of the orogen from the northeast newfoundland shelf to cape breton but extrapolation to new brunswick and quebec is unclear because of late paleozoic basin development the central mobile belt of the orogen is only a few tens of kilometres wide in southwest newfoundland and cape breton but broadens substantially to around 200 km elsewhere reflection images show a strong deep crustal fabric that runs along the orogen with a margin that crosses into the avalon zone in southern newfoundland but coincides with the avalon gander zone boundary el

a seismic based cross section of the grenville orogen in southern ontario and western quebec a schematic crustal cross section is presented for the southwestern grenville province based on reprocessed lithoprobe near vertical incidence seismic reflection data and compiled seismic refraction wide angle velocity models interpreted with geological constraints the schematic crustal architecture of the southwest grenville province from southeast to northwest comprises allochthonous crustal elements frontenac adirondack belt and composite arc belt that were assembled prior to ca 1160 ma and then deformed and transported northwest over reworked rocks of pre grenvillian laurentia and the laurentian margin primarily between 1120 and 980 ma reworked pre grenvillian laurentia and laurentian margin rocks are interpreted to extend at least 350 km southeast of the grenville front beneath all of the composite arc belt three major structural boundary zones the grenville front and adjacent grenville front tectonic zone the central metasedimentary belt boundary thrust zone and the elzevir frontenac bou

crust and upper mantle velocity structure in the appalachian orogenic belt implications for tectonic evolution the crust and upper mantle structure of the northeastern united states neus was studied by combining teleseismic and regional body wave observations with surface wave dispersion measurements the velocity models suggest that structures as much as 200 km deep and even deeper can be correlated with surficial geologic and tectonic features and that the grenville and appalachian orogenic belts show marked differences in crustal structure this has the important implication that major orogenic belts have effects that reach well into the lithosphere and are stable for extended periods of time perhaps as long as 1 b y regional travel times recorded across the neus seismic network indicate that the northern appalachians are characterized by a well defined two layer crust with a relatively high velocity lower layer the crust of the grenville province in new york state is slightly thinner than that of the new england appalachians and it is vertically homogeneous with nearly constant p and s velocities lateral variations in structure were studied using time term analysis and teleseismic p wave residuals the suture between the grenville and appalachian provinces in the northeastern united states probably occurs along a north northeast trending belt extending from northwestern vermont to southwestern connecticut high crustal velocities and or crustal thinning a linear gravity high a serpentinite belt precambrian uplifts and the taconic thrusts are found along much of this belt comparison of seismic velocities with resistivity measurements suggests that the lower crust of the grenville province may be composed of rocks with hydrous mineral phases resulting in lowered velocities and a higher poisson s ratio alternatively the rocks of the lower crust beneath the grenville province may be similar to those found on the surface while higher velocity mafic mineralogies are prevalent in the lower crust of the appalachians this is consistent with the hypothesis that the grenville crust underwent substantial reactivation thickened and became vertically uniform during the grenville orogeny in contrast the rocks of the appalachian belt probably were associated with a cycle of oceanic opening and closure which suggests an ensimatic origin of the lower crust in this region recent cocorp results indicate that the orogenic belt of the southern appalachians is allochthonous and is underlain by a basal decollement that extends eastward to the coastal plain however contrasts in structural style and tectonic evolution between the northern and southern appalachians suggest that it may not be possible to extrapolate the cocorp results to the northern appalachians north of about 41 latitude and that the suture between the grenville province and the appalachian orogenic belt in new england is located in the vicinity of or just east of the serpentinite belt

river terrace systems in north west europe an archive of environmental change uplift and early human occupation abstract staircases of large scale aggradational river terraces are a notable feature of many valleys in the temperate lattitudes particularly in areas beyond the reach of the erosive activities of pleistocene ice sheets it is now recognized that the cyclic fluctuations of climate during the quaternary have driven the generation of terraces through the direct and indirect influence of both temperature and precipitation on fluviatile activity where fossiliferous deposits are preserved within terrace sequences it is often possible to date these and to correlate them with the oceanic record thus providing an important framework for the evidence of environmental change on land middle and late pleistocene terraces in different areas can commonly be seen to have formed in synchrony with glacial interglacial cycles or with longer periodicity megacycles climatic forcing alone is insufficient to cause terraces to form however uplift is also necessary so that terrace sequences can provide a useful record of crustal movement in northwest europe where some of the best known studies of river terrace sequences have been carried out the fluviatile deposits are also an important repository for palaeolithic artefacts from which a record of early human occupation can be reconstructed

palaeoclimatic changes in the holsteinian interglacial middle pleistocene on the basis of indicator species method palynological and macrofossils remains from nowiny żukowskie site se poland abstract analysis of pollen and macroremains from the mazovian holsteinian interglacial in the nowiny ukowskie succession enabled the identification of numerous climatic indicators the applied indicator species method allowed for a detailed description of climatic changes i e warmings and coolings that occurred in this interglacial the determined ranges of temperatures that prevailed in particular periods provide a basis for an assumption that it was probably the warmest interglacial of the pleistocene the estimated temperature of the warmest month during the climatic optimum abies carpinus period may have been 2 4 c higher than in the warmest period of the holocene moreover numerous changes in humidity evidenced by frequent oscillations from oceanic to continental climate are particularly important the cool periods are generally marked by the presence of betula nana selaginella selaginoides and s helvetica heliophytes such as helianthemum nummularium and shrubs of ephedra and hippophae rhamnoides the warmest period is documented by the occurrence of thermophylous trees e g pterocarya fraxinifolia juglans shrubs e g buxus sempervirens and vitis sylvestris as well as hedera helix viscum and aquatic plants e g brasenia borysthenica

comparison of the paleoclimatic significance of higher land plant biomarker concentrations and pollen data a case study of lake sediments from the holsteinian interglacial abstract a sediment core from the dethlingen paleolake holsteinian interglacial northern germany was subjected to integrated organic geochemical and palynological paleobotanical analyses in order to reconstruct past environmental conditions the fractionated lipid extracts were investigated using gas chromatography mass spectrometry gc ms and gc combustion isotopic ratio ms ring a aromatized pentacyclic triterpenoids most likely glutinane derivatives were the only higher plant derived pentacyclic triterpenoids found the saturated ring a degraded triterpenoid des a lupane was the most abundant aliphatic hydrocarbon throughout the core based on published pollen data which imply the strong presence of betula and alnus around the paleolake the des a lupane would be expected to originate mainly from lupane type precursors synthesized by betulaceae the carbon isotopic composition of des a lupane varied from 28 2 to 30 6 and no significant trend or isotopic shift was observed however the discrepancy between the variation in pollen data and biomarker concentration i e quasi absence of diterpenoids in the core argues for a scenario in which the two proxies represent different components of the vegetation in the catchment area of the paleolake

dating the earliest lowland glaciation of eastern england a pre mis 12 early middle pleistocene happisburgh glaciation this paper outlines the evidence for the happisburgh glaciation the first middle pleistocene glaciation of lowland eastern england and the adjacent margins of the north sea basin we propose that this glaciation occurred during a pre elsterian anglian mis 12 cold stage based on evidence of clasts of till erratics and heavy minerals from the third youngest terrace of the pre glacial bytham river in southern norfolk the heavy minerals show a progressive increase in glacially sourced materials from the bottom to the top of the bytham river third terrace sediments the till clasts are correlated with the extensive deposits of the happisburgh formation on the basis of their colour heavy minerals and particle size properties thus the happisburgh glaciation occurred during the accumulation of the bytham river terrace deposits and prior to mis 12 when the bytham river system was destroyed by the anglian glaciation in the absence of any geochronology or robust biostratigraphy the age of the happisburgh glaciation is estimated by the synchronisation of the pattern of large scale river activity with patterns of milankovitch forced global climate change on this basis and assuming the british ice sheet acted in phase with global patterns of ice volume the happisburgh glaciation is considered to have occurred during mis 16 and be equivalent of the don glaciation of eastern europe

european middle pleistocene loess chronostratigraphy some considerations based on evidence from the wels site austria a combination of site logging luminescence dating and comparison with different long and continuous records of past environmental conditions is used to elaborate an age model for the wels loess palaeosol site austria according to this model marine isotope stage mis 7 is reflected in the development of three red forest soils luvisols at this particular site this is contrary to previous assumptions that suggested the development of such soils in the region at 100 ka cyclicity if these results are correct this may question some previous conclusions regarding the general loess stratigraphy in many parts of europe

climate oscillations of the holsteinian mazovian interglacial recorded in shell morphometry of viviparus diluvianus kunth 1865 from eastern poland abstract lake deposits of the holsteinian mazovian interglacial from eastern poland are characterised by a rich occurrence of mollusc shells mollusc assemblages from five sites ortel krolewski szymanowo ossowka hrud ii and roskosz are presented populations of the snail viviparus diluvianus kunth are subjected to biometric analysis to verify how climatic changes in the holsteinian interglacial influenced the shell morphology the pollen analysis allows assignment of sediments from different sites to the certain parts of the interglacial characterised by influences of maritime or continental climates a combination of palaeobotanical and mollusc data shows that variability in shell morphometry of v diluvianus is strongly connected with climate conditions the strongest correlation with the climate shows slimness of the shell it appears that during the periods with predominating oceanic climate the mean slimness of the shell increases smaller and wider individuals are typical of the climate with continental features and lake shallowing thus v diluvianus shells from eastern poland are used to reconstruct climate from taxus zone up to the end of the climatic optimum of the holsteinian mazovian interglacial mis 11 carpinus abies zone

crustal structure of the adirondacks determined from broadband teleseismic waveform modeling broadband receiver functions developed from teleseismic p waveforms recorded on the midperiod passband of the department of energy s regional seismic test network station rsny are analyzed to examine the crustal structure beneath the adirondack highlands of upstate new york radial receiver functions are inverted in the time domain to determine the vertical shear velocity structure at four distinct back azimuths lateral changes in structure are identified by examining azimuthal variations in the vertical structure southeast of rsny our model consists of a thick crust including a broad crust mantle transition the most prominent structure is a high velocity zone shear velocity 4 0 km s between 18 and 26 km depth which overlies a lower crust of low average shear velocity 3 7 km s the extent of the high velocity zone correlates in depth with a highly reflective zone in consortium for continental reflection profiling profiles se of rsny while the deep low velocity zone may be correlated with a broad electrical conductivity anomaly in the adirondacks this general structure is also seen sw of rsny but is more difficult to document at nw and ne azimuths

crustal thickness and vp vs variations in the grenville orogen ontario canada from analysis of teleseismic receiver functions abstract we have developed a simple semblance weighted stacking technique to estimate crustal thickness and average vp vs ratio using teleseismic receiver functions we have applied our method to data from 32 broadband seismograph stations that cover a 700 400 km2 region of the grenville orogen a 1 2 0 98 ga himalayan scale collisional belt in eastern north america our seismograph network partly overlaps with l ithoprobe and other crustal refraction surveys in 8 out of 9 cases where a crustal refraction profile passes within 30 km of a seismograph station the two independent crustal thickness estimates agree to within 7 our regional crustal thickness model constructed using both teleseismic and refraction observations ranges between 34 0 and 52 4 km crustal thickness trends show a strong correlation with geological belts but do not correlate with surface topography and are far in excess of relief required to maintain local isostatic equilibrium the thickest crust 52 4 1 7 km was found at a station located within the 1 1 ga mid continent failed rift the central gneiss belt which contains rocks exhumed from deep levels of the crust is characterized by vp vs ranging from 1 78 to 1 85 in other parts of the grenville orogen vp vs is found to be generally less than 1 80 the thinnest crust 34 5 37 0 km occurs northeast of the 0 7 ga ottawa bonnechere graben and correlates with areas of high intraplate seismicity

marine isotope stage 11 palaeoclimates palaeoenvironments and its role as an analogue for the current interglacial abstract interglacials of the quaternary period are currently the focus of a great deal of attention within the scientific community this is primarily because they play a vital role in distinguishing between natural and human climate change in the current interglacial and in understanding how the holocene would evolve in the absence of anthropogenic greenhouse warming in this respect marine isotope stage 11 mis 11 ca 410 000 yr bp is one of the key interglacial stages of the past 450 000 yr the pattern of insolation variability that occurs during mis 11 matches that which occurs in the holocene more closely than in any other warm stage of the past half a million years in addition there is now an extensive range of evidence for mis 11 palaeoclimates and palaeoenvironments from marine ice core lacustrine and terrestrial sequences the aim of this paper is to provide a comprehensive review of the current state of our understanding of mis 11 this is the first paper to provide a detailed review of mis 11 that incorporates the wide range of marine ice core long lacustrine and terrestrial records that have been generated over the last ten years since the last major overview crucially it is the first review of mis 11 that incorporates a detailed synthesis of the high resolution terrestrial sequences of western and central europe this paper therefore provides a holistic integration of a diverse range of proxies and archives to provide a detailed understanding of the expression of mis 11 in the earth system in particular the review focuses on 1 the climatic background of mis 11 2 the robustness of the identification of mis 11 in a diverse range of sequences 3 the climatic structure of mis 11 4 the magnitude of warmth that occurred in this warm stage 5 mis 11 sea level magnitude and variability 6 the duration of mis 11 7 evidence for abrupt climatic events within the interglacial of mis 11 and 8 precipitation patterns and trends during this interglacial the paper concludes by considering how useful mis 11 is as an analogue for holocene climates and compares it with other proposed analogues such as mis 19 with particular reference to the early anthropogenic hypothesis

shear wave structure in the grenville province beneath the lower great lakes region from rayleigh wave tomography 1 we have constructed a high resolution 3 d shear wave velocity model of the upper mantle beneath the grenville province in the lower great lakes region a two plane wave tomography method was applied to fundamental mode rayleigh wave data recorded at 35 broadband seismic stations rayleigh wave phase velocities were obtained at 15 periods from 20 s to 143 s and then inverted for shear wave velocity variation a high velocity lid to 150 km depth is imaged beneath most of the studied grenville province one low velocity anomaly of 4 appears at a failed rift in the northeast above 100 km depth coinciding with the great meteor hot spot track and the high seismicity band which can be interpreted as high temperature and high iron and or volatile content related to the hot spot activity low velocity anomaly of 2 at the depths of 100 200 km are found beneath the east of lake ontario and lake huron where the lithosphere is relatively thin these anomalies follow the nw se trend of the slow indentation imaged on the continental scale models we conclude that the location of low velocity anomalies is not only related to the hot spot track but also controlled by the pre existing lithosphere morphology and strength a high velocity column appears between southern lake ontario and the appalachian front centered at 100 km depth it is likely caused by high mg content at the formation of the lithosphere or the presence of ecologite or garnet phases generated during the opening and closure of the iapetus ocean

a tale of two sutures cocorp s deep seismic surveys of the grenville province in the eastern u s midcontinent a pair of oppositely dipping crustal scale shear zones imaged within grenville basement beneath the paleozoic cover of ohio can be correlated via geopotential lineaments with similarly oriented geologic and seismically imaged structures hundreds of kilometres to the northeast and southwest suggesting a relatively simple structural framework for the eastern midcontinent region an east dipping zone extending from lake huron through western ohio and possibly farther southwest marks the western edge of the grenville province perhaps of greater consequence to an understanding of grenville tectonics is the discovery of a west dipping zone underlying the appalachian basin from northern alabama to new york within the grenville province correlation of this feature with the seismogenic clarendon linden fault in western new york and a boundary between terranes containing magmatic arc rocks exposed in canada suggests that it could mark the site of an intra grenville province suture zone implications of this interpretation are that the precambrian foundation of the eastern u s midcontinent comprises a relatively simple assemblage of laterally extensive terranes or belts of coeval terranes accreted by familiar plate tectonic processes and that deep seismic profiling is an effective tool for mapping the three dimensional distribution of these terranes

revised limit of the saalian ice sheet in central europe abstract geological investigations in the southern part of the polish belarusian cross border area were focused on correlation of main middle pleistocene stratigraphic units and on extent of the ice sheet of the saalian glaciation determination of regional stratotype horizons establishing new key sites and sections of regional significance for central europe were based mostly on vegetation and paleoclimate changes recorded in glacial and interglacial lake deposits results of stratigraphical investigations abolished a predominant palaeogeographic image on ice sheet limits in this area the saalian maximum ice sheet limit was similar or even less extensive than during the subordinate warta stadial most of the area between the middle vistula in poland and the middle dnieper in belarus and the ukraine was ice free during this glaciation on the other hand immense glacial lobes during saalian in the middle vistula and the middle dnieper valleys have not advanced presumably in the same time and were fed by ice moving from different parts of scandinavia diversified pleistocene tectonic uplifting in the area influenced much dynamics of the penultimate ice sheet in this part of europe

new evidence for vegetation development and timing of upper middle pleistocene interglacials in northern germany and tentative correlations abstract this paper discusses palynological investigations and new 230th u ages of two upper middle pleistocene sequences of the formerly glaciated northern german lowlands the reinsdorf sequence at the open mine of schoningen lower saxony and the north friesian site of leck new 230th u ages of late interglacial organic layers of the archaeological lake margin site of the reinsdorf sequence ranging from 280 to 343 ka give evidence for a correlation of those deposits with marine isotope stage mis 9 near and long distance correlation by means of palynological investigations of holsteinian and related interglacial continental deposits and their correlation with the mis is discussed isotopic investigations of uranium and thorium from organic rich mud deposits at core leck 8 point to an open system and age estimation by 230th u dating remains therefore unclear compared to other upper middle pleistocene warm periods in north germany correlations of the leck interglacial with the holsteinian and the reinsdorf interglacial can be excluded in comparison with sediment successions from the nachtigall section at hoxter and the section ottostrase at gottingen the leck interglacial is discussed as a correlative of a warm temperate phase of mis 7

regional wave propagation in new england and new york we validate and improve 1d velocity models of the two main crustal provinces in the northeastern united states neus using seismograms from the 20 april 2002 m 5 au sable forks earthquake which is the largest earthquake in the region to be recorded by multiple recently deployed good quality regional broad band stations to predict and mitigate the effects of future earthquakes in the north eastern united states more information is needed regarding both the local earthquake sources and how seismic waves travel through the region we investigate the source and regional wave propagation for the au sable forks earthquake the earthquake epicenter is located near the boundary of two distinct geological provinces the appalachian new england and grenville new york we use a forward modeling approach to study the waveforms recorded at 16 stations located within 400 km of the epicenter we generate synthetic seismograms using the frequency wavenumber method testing several published models for the two provinces several models per form well at low frequencies 0 1 hz we refine these models and generate two alternative 1d crustal models for intermediate frequencies 1 hz of engineering interest our new grenville model performs better than previously published models for all six source station paths modeled in that province according to goodness of fit statistics variance reduction and correlation coefficient our alternative appalachian model improves the fit of synthetics to data for five of the ten paths modeled in that province from the results we identify two specific sources of wave field complex ities that should be investigated in future studies of earthquake ground motions in neus 3 azimuthal anisotropy in the appalachian province and complex wave paths along the boundary between the two provinces

eight glacial cycles from an antarctic ice core the antarctic vostok ice core provided compelling evidence of the nature of climate and of climate feedbacks over the past 420 000 years marine records suggest that the amplitude of climate variability was smaller before that time but such records are often poorly resolved moreover it is not possible to infer the abundance of greenhouse gases in the atmosphere from marine records here we report the recovery of a deep ice core from dome c antarctica that provides a climate record for the past 740 000 years for the four most recent glacial cycles the data agree well with the record from vostok the earlier period between 740 000 and 430 000 years ago was characterized by less pronounced warmth in interglacial periods in antarctica but a higher proportion of each cycle was spent in the warm mode the transition from glacial to interglacial conditions about 430 000 years ago termination v resembles the transition into the present interglacial period in terms of the magnitude of change in temperatures and greenhouse gases but there are significant differences in the patterns of change the interglacial stage following termination v was exceptionally long 28 000 years compared to for example the 12 000 years recorded so far in the present interglacial period given the similarities between this earlier warm period and today our results may imply that without human intervention a climate similar to the present one would extend well into the future

eclogite facies shear zones deep crustal reflectors strongly foliated eclogite facies rocks in 30 150 m thick shear zones of caledonian age occur within a grenvillian garnet granulite facies gabbro anorthosite terrain in the bergen arcs of norway the predominant eclogite facies mineral assemblages in the shear zones are omphacite garnet zoisite kyanite in gabbroic anorthosite and omphacite garnet in gabbro eclogite facies rocks in shear zones are generally fine grained alternating omphacite garnet and kyanite clinozoisite rich layers define gneissic layering a strong shape preferred orientation of omphacite kyanite and white mica phengitic muscovite and or paragonite define the foliation the anorthositic eclogites show omphacite b axis maxima approximately normal to the foliation and c axis girdles within the foliation plane p wave velocities v determined at confining pressures to 600 mpa for samples from eciogite facies shear zones range from 8 3 to 8 5 km s l and anisotropy ranges from 1 to 7 the few samples with more pronounced anisotropy tend to be approximately transversely isotropic with minimum velocities for propagation directions normal to foliation and maximum velocities for propagation directions parallel to foliation the fast propagation direction lies within the c axis girdles parallel to foliation and the slow propagation direction is parallel to the b axis concentration normal to foliation in samples for which omphacite crystallographic preferred orientation was determined v for the granulite facies protoliths average about 7 5 km s high calculated reflection coefficients for these shear zones 0 04 0 14 indicate that they are excellent candidates for deep crustal reflectors in portions of crust that experienced high pressure conditions but escaped thermal reactivation

applications of seismic pattern recognition and gravity inversion techniques to obtain enhanced subsurface images of the earth s crust under the central metasedimentary belt grenville province ontario summary project lithoprobe s abitibi grenville transect seismic reflection lines 32 and 33 traverse the exposed central metasedimentary belt cmb located in the grenville province of the precambrian shield of canada in southern ontario these seismic lines image a zone with a protracted deformational history spanning more than 300 myr detailed examination of the commercially processed stacked sections reveals a number of significant deficiencies in some important areas the image quality in these zones of reduced coherency needs to be enhanced to examine specific features and their relation to the surface geology examination of near vertical seismic data from lines 32 and 33 revealed that the signal to noise ratio was not improved by stacking due to misalignment of signals even after static normal moveout corrections and residual static corrections the presumed reason is that reflected seismic energy following long ray paths in heterogeneous media suffers from relative advances and delays in its propagation and hence arrives at slightly different times at the receivers tending to be poorly aligned relative to its theoretical traveltime curves a pattern recognition pr method for signal enhancement followed by energy stacking in moving time windows was used in this study to improve the images in spite of misalignments reprocessing has refined the geometry of the reflection profiles the objective of this paper is to use enhanced images of the seismic reflection data obtained by using a pr approach together with gravity data using 2 5 d forward and 3 d inversion routines to give an improved model of subsurface structure in the vicinity of lines 32 and 33 line 32 is dominated by southeast dipping reflectors soling into the lower crust the listric geometry of the strong reflection packages of the cmb boundary thrust zone is interpreted to represent a crustal scale ramp flat geometry that accommodated northwest directed tectonic transport of the cmb this interpretation is also supported by the gravity data

timing of massive fleuve manche discharges over the last 350 kyr insights into the european ice sheet oscillations and the european drainage network from mis 10 to 2 continuous high resolution mass accumulation rates mar and x ray fluorescence xrf measurements from marine sediment records in the bay of biscay ne atlantic have allowed the determination of the timing and the amplitude of the fleuve manche channel river discharges during glacial stages mis 10 mis 8 mis 6 and mis 4 2 these results have yielded detailed insight into the middle and late pleistocene glaciations in europe and the drainage network of the western and central european rivers over the last 350 kyr this study provides clear evidence that the fleuve manche connected the southern north sea basin with the bay of biscay during each glacial period and reveals that fleuve manche activity during the glaciations mis 10 and mis 8 was significantly less than during mis 6 and mis 2 we correlate the significant fleuve manche activity detected during mis 6 and mis 2 with the extensive saalian drenthe substage and the weichselian glaciations respectively confirming that the major elsterian glaciation precedes the glacial mis 10 in detail massive fleuve manche discharges occurred at ca 155 ka mid mis 6 and during termination i while no significant discharges are found during termination ii it is assumed that a substantial retreat of the european ice sheet at ca 155 kyr followed by the formation of ice free conditions between the british isles and scandinavia until termination ii allowed meltwater to flow northwards through the north sea basin during the second part of the mis 6 we assume that this glacial pattern corresponds to the warthe substage glacial maximum therefore indicating that the data presented here equates to the drenthe and the warthe glacial advances at ca 175 160 ka and ca 150 140 ka respectively finally the correlation of our records with odp site 980 reveals that massive fleuve manche discharges related to partial or complete melting of the european ice masses were synchronous with strong decreases in both the rate of deep water formation and the strength of the atlantic thermohaline circulation fleuve manche discharges over the last 350 kyr probably participated with other meltwater sources in the collapse of the thermohaline circulation by freshening the northern atlantic surface water

the middle pleistocene fluvial sequence at uichteritz central germany chronological framework paleoenvironmental history and early human presence during mis 11 abstract the site of uichteritz saxony anhalt germany is a quaternary gravel quarry hosting several middle pleistocene fluvial units of the saale river this fluvial archive contains detailed information on 1 the timing of middle pleistocene fluvial aggradation and erosion periods in the region 2 the driving forces for those alternations as well as 3 early human presence indicated by the presence of lower paleolithic stone artefacts here we establish a luminescence based numerical chronology at uichteritz additionally geophysical sedimentological and micromorphological analyses were applied to obtain information on depositional and post depositional processes of the fluvial sequence our results point to several fluvial aggradation periods between ca 420 and 180 ka a first fluvial unit was deposited during the late elsterian period followed by formation of a luvisol during mis 11 and its fluvial reworking at the transition from mis 11 to mis 10 and or during early mis 10 these mis 10 11 deposits with an age of about 400 ka also contain reworked lower paleolithic stone artefacts that document the initial appearance of humans in northwestern central europe during mis 11 after a period of fluvial incision during mis 10 which was accompanied by a change in the course of the saale river several stacked fluvial sequences of the saalian main terrace smt formed between mis 8 and mis 6 mainly during cold climatic periods our age estimates confirm the correlation of the elsterian ice advances with mis 12 and the saalian ice advances with later mis 6

geochemical evidence for a revised precambrian sequence in the northwest adirondacks new york middle proterozoic metasedimentary and metavolcanic rocks in the northwest adirondacks are assigned into four lithostratigraphic units basal hyde school gneiss that herein is given formational status lower marble popple hill gneiss formation and upper marble a variety of stratigraphic columns have been proposed for this complexly deformed terrane the most recent being a column by wiener and others 1984 their basal formation the alexandria bay gneiss is defined from rocks that include the rockport granite gneiss near rockport ontario and alexandria bay new york as well as leucogneisses in 14 structural domes throughout the northwest adirondacks we believe that these rocks have a diverse origin one being intrusive the other volcanic ash their uppermost formation the pleasant lake gneiss includes granitoid gneisses near rossie village and pleasant lake that they suggest are illitic arkoses but we give field geochemical and geochronological evidence for an intrusive origin the gneisses near rossie village have a whole rock rb sr age of 1 160 42 m y ir 0 7036 0 0004 and similar gneisses near antwerp village are 1 197 53 m y ir 0 7034 0 0005 these ages are younger than the zircon u pb ages of 1 280 1 250 m y generally obtained for metasedimentary and metavolcanic rocks in the central metasedimentary belt of ontario we urge abandonment of the five formations and two groups proposed by wiener and others 1984 on the basis of an intrusive origin for the gneisses near rockport and rossie villages and on stratigraphic correlations of recent studies the stratigraphy of four formations proposed herein with a generalized geologic map of the northwest adirondacks may lead to correlation with carbonate sequences in the central metasedimentary belt and with rocks of the adirondack highlands to the east

origin of granulite terranes and the formation of the lowermost continental crust differences in composition and pressures of equilibration between exposed regional granulite terranes and suites of granulite xenoliths of crustal origin indicate that granulite terranes do not represent exhumed lowermost crust as had been thought but rather middle and lower middle crustal levels application of well calibrated barometers indicate that exposed granulites record equilibration pressures of 0 6 to 0 8 gigapascal 20 to 30 kilometers depth of burial whereas granulite xenoliths which also tend to be more mafic record pressures of at least 1 0 to 1 5 gigapascals 35 to 50 kilometers depth of burial thickening of the crust by the crystallization of mafic magmas at the crust mantle boundary may account for both the formation of regional granulite terranes at shallower depths and the formation of deep seated mafic crust represented by many xenolith suites

tidal influence on self potential measurements long term surface and borehole self potential sp monitoring was conducted in the uk chalk aquifer at two sites the coastal site is c 1 7 km from the coast and the inland site is c 80 km from the coast at both sites power spectral density analysis revealed that sp data contain the main ocean tidal periodic components however the principal lunar component m2 the dominant ocean tidal component was most significant at the coastal site the m2 signal in surface referenced sp data at the inland site was partly due to telluric currents caused by the geomagnetic ocean dynamo earth and or atmospheric tides also contributed as the sp power spectrum was not typical of a telluric electric field the m2 component in borehole referenced data at the inland site was below the significance level of the analysis method and was two orders of magnitude smaller than the m2 signal in borehole referenced sp data at the coastal site the tidal response of the sp data in the coastal borehole is therefore primarily driven by ocean tides these cause changes in fluid pressure and chemical concentration gradients within the coastal aquifer leading to time varying electrokinetic and exclusion diffusion potentials borehole referenced sp measurements could be used to characterize and monitor tidal processes in coastal aquifers such as the intrusion of seawater

the complexity of the crust and moho under the southeastern superior and grenville provinces of the canadian shield from seismic refraction wide angle reflection data the major features of the individual velocity models poisson s ratio values and crustal complexity derived from the interpretation of seismic data sets from four long range seismic refraction wide angle reflection experiments are summarized the experiments were conducted from 1982 92 in the southeastern portion of the canadian shield in the conventional analysis of seismic refraction wide angle reflection data only the onset times and amplitudes of the major arrival phases are used to derive seismic velocity models of the region under study these models are over smoothed have a number of intermediate discontinuities are unable to explain the pg coda and bear very little resemblance to the models derived from the analysis of near vertical seismic reflection data in this paper some of the differences between seismic models derived from near vertical reflection analysis and those from refraction analysis are reconciled from an analysis of the wide angle reflection fields of the crustal coda wav

pollen analytical biostratigraphy of the last five climatic cycles from a long continental sequence from the velay region massif central france in the volcanic region of velay massif central france lake sediment sequences derived from maar craters situated close to one another ribains praclaux and lac du bouchet have been correlated on the basis of tephrostratigraphical analyses this has enabled the construction of a sequence 2980 pollen spectra that begins during the glaciation preceding the holsteinian and ends in the present this sequence covers the period from 450 ka i e from the end of marine oxygen isotope stage 12 to the present time and includes five climatic cycles the study of a second core from the praclaux site completed the long velay sequence the biostratigraphy of the whole sequence is described in detail and illustrated by a synthetic and simplified pollen diagram thirteen temperate forest episodes interglacials or interstadials and as many cold periods glacials or stadials are defined each temperate episode is characterised by particular forest development and vegetation dynamics and all of them with the exception of the holocene begin and end with a pinus forest the vegetation dynamics observed during the holocene resemble more closely those recorded during the interstadials than during the interglacials copyright 2000 john wiley sons ltd

archean and proterozoic crustal evolution evidence from crustal seismology seismic velocity models for archean and proterozoic provinces throughout the world are analyzed the thickness of the crust in archean provinces is generally found to be about 35 km except at collisional boundaries whereas proterozoic crust has a significantly greater thickness of about 45 km and has a substantially thicker high velocity 7 0 km s layer at the base we consider two models that may explain these differences the first model attributes the difference to a change in the composition of the upper mantle the higher temperatures in the archean mantle led to the eruption of komatiitic lavas resulting in an ultradepleted lithosphere unable to produce significant volumes of basaltic melt proterozoic crust developed above fertile mantle and subsequent partial melting resulted in basaltic underplating and crustal inflation in the second model convection in the hot archean mantle is considered to have been too turbulent to sustain stable long lived subduction zones by the proterozoic the mantle had cooled sufficiently for substantial island and continental arcs to be constructed and the high velocity basal layer was formed by basaltic underplating

sm nd and u pb isotopic evidence of juvenile crust in the adirondack lowlands and implications for the evolution of the adirondack mts sm nd investigations of hyde school gneiss yield t dm ages only slightly older than u pb zircon emplacement ages thus indicating substantial addition of juvenile calcalkaline crust to the adirondack lowlands at ca 1300 ma juvenile crust of similar age has been recognized within the adirondack highlands the elzevir terrane further to the northwest in canada and in the green mts of vermont suggesting the presence of an extensive magmatic arc at that time while the precise nature of the arc remains uncertain an indonesian analogue is favored u pb zircon ages of ca 1150 1160 ma are reported for lowlands samples of syenitic and granitic rocks belonging to the anorthosite mangerite charnockite granite amcg suite that also occurs in the highlands as well as in the canadian sector of the frontenac terrane the regional occurrence of these anorogenic intrusions indicates that the adirondack highlands and frontenac terrane including the adirondack lowlands constituted a single contiguous entity

crustal velocity structure of the superior and grenville provinces of the southeastern canadian shield the 1992 lithoprobe abitibi grenville seismic refraction experiment was conducted using four profiles across the grenville and superior provinces of the southeastern canadian shield delay time analysis and tomographic inversion of the data set demonstrate significant lateral and vertical variations in crustal velocities from one terrane to another with the largest velocity values occurring underneath the central gneiss and the central metasedimentary belts south of the grenville front the grenville front tectonic zone is imaged as a southeast dipping region of anomalous velocity gradients extending to the moho the velocity anomaly maps suggest an archean crust may extend horizontally 140 km beneath the northern grenville province near surface velocity anomalies correlate well with the known geology the most prominent of these is the sudbury structure which is well mapped as a low velocity basinal structure the tomography images also suggest underthrusting of the pontiac and quetico subprovinces

shear velocity structure and azimuthal anisotropy beneath eastern north america from rayleigh wave inversion 1 we have obtained shear velocity structure beneath the northeastern united states and southeastern canada using rayleigh wave phases and amplitudes thin crust 36 42 km is observed along the atlantic coast and in the eastern appalachian orogen and thick crust 42 46 km is imaged in the western appalachians and in the western new york portion of the grenville province the variation of crustal thickness correlates well with the observed bouguer gravity anomalies in the upper mantle the high velocity continental keel of cratonic north america is present in the western part of the study area while a broad low velocity region is imaged in new england from the hudson river valley to the white mountains this low velocity anomaly is probably the consequence of past heating of the lithospheric mantle associated with the monteregian hotspot and may represent intrusion of asthenosphere into the edge of the keel in addition to lateral variations in velocity we estimate the azimuthal dependence of phase velocity strong and relatively uniform shear wave splitting is observed in the study region but at periods of 100 s or less the average azimuthal anisotropy of rayleigh waves is less than 1 and is not significantly different from zero at any individual period this small degree of azimuthal anisotropy is not consistent with a substantial contribution to shear wave splitting from fossil anisotropy in the lithosphere much of the source of the shear wave splitting must lie deeper than 200 km

adirondack highlands northwest lowlands boundary a multiply folded intrusive contact with fold associated mylonitization the boundary between the adirondack highlands and the northwest lowlands near harrisville new york is a multiply folded intrusive contact between metamorphosed sedimentary rocks of the lowlands and metamorphosed intrusive rocks of the diana complex in the highlands this is shown by detailed geologic mapping and analysis of stratigraphy and minor structural features regionally developed protomylonitic foliation in the diana complex is an axial plane foliation formed during isoclinal folding of dry quartz syenite at granulite facies metamorphic grade lack of major post intrusive fault displacement along the diana complex northwest lowlands boundary is demonstrated by correlation of xenoliths in the diana complex with immediately adjacent metamorphosed sedimentary rock units of the northwest lowlands and by continuity of major folds across the boundary a stratigraphic succession consisting of seven rock units has been recognized in northwest lowlands rocks of the harrisville area rocks in these units include from oldest to youngest 1 garnet sillimanite cordierite gneiss 2 rusty pelitic gneiss with biotite gneiss pyroxene amphibolite and quartzite 3 graphitic calcite marble 4 siliceous marble 5 rusty calc silicate rocks 6 diopside gneiss and 7 calc silicate granulite four phases of folding are evident in these stratigraphic units but only the last three phases affect intrusive quartz syenite gneisses of the diana complex first phase isoclinal folds in bedding have a pervasive axial plane foliation which is the regional foliation associated regional lineations are parallel to first phase fold axes foliation and lineation formed during the first phase of folding were deformed by second phase isoclinal folds which have a weak to strong axial plane foliation or slip cleavage quartz syenite of the diana complex intruded folded metamorphosed sedimentary rocks early during second phase folding and was itself isoclinally folded somewhat later during the second phase isoclinal folding of quartz syenite gneiss is associated with development of protomylonitic to mylonitic axial plane foliation which is most intense in the northwest border zone of the diana complex due to lithic contrast with rocks northwest of the border third phase folds are isoclinal to open and are locally characterized by axial plane slip cleavage or fracture cleavage the axial surfaces of folds associated with the first three phases of deformation have a general northeasterly trend and northwesterly dip but their axes have varied plunges two dimensional heart and anchor and hook patterns are a product of interference of second and third phase folds fourth phase deformation resulted in northwest trending open folds with locally developed axial plane slip or fracture cleavage interference of third and fourth phase folds is manifest in dome and basin patterns that are elongate to the northeast and overturned to the southeast similar to dome and basin patterns throughout the northwest lowlands late stage ductile shearing produced very fine grained thin mylonite and ultramylonite in shear zones that transect the preexisting protomylonite foliation in quartz syenite gneiss later brittle deformation resulted in closely spaced fractures quartz and epidote veins and local minor faults however no evidence for major faulting has been observed along this part of the adirondack highlands northwest lowlands boundary

adirondack appalachian crustal structure the cocorp northeast traverse reflection surveys from northeastern new york and central vermont the first elements of a cocorp seismic traverse of grenville and appalachian terranes in the northeastern united states indicate that an unusual zone of layered reflections characterizes the lower crust beneath the eastern adirondacks and that grenville age basement of the green mountains may actually be allochthonous perhaps thrust over paleozoic shelf rocks the top of the adirondack deep layered sequence is found at about 20 km beneath the marcy meta anorthosite massif it appears to dip about 10 northwestward and wedge out against more horizontal reflections at about 28 km this intracrustal sequence may correspond with a previously inferred increase in electrical conductivity possible interpretations range from its being a layered igneous complex to its representing a tectonically buried metasedimentary assemblage although graphitic schists and iron or sulfide segregations in such an assemblage might contribute to its electrical characteristics the problematical issue of water in the lower crust if and how it got there and remained is again raised if not resolved other intrabasement features include major east and west dipping reflections possibly corresponding to faults arched reflections that may represent folds a well defined lens shaped zone virtually devoid of reflections and possible moho reflections unequivocal sub moho reflections are absent superimposed at shallower levels on the eastern part of the traverse are appalachian structures reflections down to about 4 5 km beneath the taconic mountains are interpreted to represent paleozoic shelf sediments of the middlebury synclinorium underlying the taconic allochthons possibly correlative although less well defined reflections appear to extend in disrupted fashion beneath the precambrian rocks of the green mountains suggesting a major basement overthrust the inferred decollement for this overthrust steepens rapidly beneath the east flank of the green mountains east dipping reflections at the east side of the green mountains may represent another major thrust zone involving basement and overlying metasedimentary slices the basement overthrusting suggested by this study is similar in certain respects to the style if not the extent of that demonstrated by previous cocorp surveys in the southern appalachians

seismic velocities in the shallow crust of western new england and northern new york the ontario new york new england refraction study o nynex provides a set of high quality data for a tomographic study of an intraplate continental region with low seismic activity this study focuses on the region crossed by the united states part of the o nynex profile tomographic inversion of the travel time data is used to construct a three dimensional model of the p and s wave seismic velocity distribution within the shallow crust of this region velocity structure is resolved in the top 15 km of the crust with the most detailed picture obtained for the depth range between 1 and 5 km the upper crust of the proterozoic grenville province is found to have a p wave velocity 0 2 to 0 3 km sec higher than the paleozoic appalachians the area of anorthositic intrusions within the adirondack mountains is characterized by p wave velocities 0 3 km sec higher and s wave velocities 0 1 km sec higher than the average values for the grenville province this high velocity anomaly extends to the depth over 5 km possibly as deep as 16 km the velocity structure of central vermont is found to be closer to that of the grenville province than to the rest of the appalachians central new hampshire shows relatively small lateral variation of seismic velocity no strong correlation is seen between velocity anomalies and intrusive bodies of the white mountains magma series

differentiation of mis 9 and mis 11 in the continental record vegetational faunal aminostratigraphic and sea level evidence from coastal sites in essex uk multidisciplinary investigations of the vegetational faunal and sea level history inferred from the infills of buried channels on the coast of eastern essex have a direct bearing on the differentiation of mis 11 and mis 9 in continental records new data are presented from cudmore grove an important site on mersea island that can be linked to the terrace sequence of the river thames the vegetational history has been reconstructed from a pollen sequence covering much of the interglacial represented the temperate nature of the climate is apparent from a range of fossil groups including plant remains vertebrates especially the rich herpetofauna molluscs and beetles which all have strong thermophilous components the beetle data have been used to derive a mutual climatic range reconstruction suggesting that mean july temperatures were about 2 c warmer than modern values for southeast england whereas mean january temperatures may have been slightly colder the sea level history has been reconstructed from the molluscs ostracods and especially the diatoms which indicate that the marine transgression occurred considerably earlier in the interglacial cycle than at the neighbouring hoxnian site at clacton there are a number of palynological similarities between the sequence at cudmore grove and clacton especially the presence of abies and the occurrence of azolla filiculoides megaspores moreover both sites have yielded palaeolithic archaeology indeed the latter is the type site of the clactonian flake and core industry however the sites can be differentiated on the basis of mammalian biostratigraphy new aminostratigraphic data as well as the differences in the sea level history the combined evidence suggests that the infill of the channel at cudmore grove accumulated during mis 9 whereas the deposits at clacton formed during mis 11 the infill of a much later channel yielding non marine molluscs and vertebrates including hippopotamus appears to have formed during the ipswichian mis 5e this evidence is compared with other important sites of late middle pleistocene age in britain and elsewhere on the continent and the importance of a multidisciplinary approach is stressed

reconciling deep seismic refraction and reflection data from the grenvillian appalachian boundary in western new england abstract the grenvillian appalachian boundary is characterized by pervasive mylonitic deformation and retrograde alteration of a suite of imbricated allochthonous and parautochthonous gneisses that were thrust upon the grenvillian continental margin during the lower paleozoic seismic reflection profiling across this structural boundary zone reveals prominent dipping reflectors interpreted as overthrust basement slices parautochthons of the green mountain anticlinorium in contrast a seismic refraction study of the grenvillian appalachian boundary reveals a sub horizontally layered seismic velocity model that is difficult to reconcile with the pronounced sub vertical structures observed in the green mountains a suite of rock samples was collected from the green mountain anticlinorium and measured at high pressures in the laboratory to determine the seismic properties of these allochthonous and parautochthonous gneisses the laboratory measured seismic velocities agree favorably with the modelled velocity structure across the grenvillian appalachian boundary suggesting that the rock samples are reliable indicators of the rock mass as whole samples of the parautochthonous grenvillian basement exposed in the green mountains have lower velocities by about 0 5 km s than lithologically equivalent units exposed in the eastern adirondack highlands velocity reduction in the green mountain parautochthons can be accounted for by retrograde metamorphic alteration hydration of the paragneisses seismic anisotropies ranging from 2 to 12 in the mylonitized green mountain paragneisses may also contribute to the observation of lower seismic velocities where the direction of ray propagation is normal to the foliation the velocity properties of the green mountain paragneisses are thus insufficiently different from the mantling appalachian allochthons to permit their resolution by the ontario new york new england seismic refraction profile

stratigraphy and chronology of the periphery of the scandinavian ice sheet at the foot of the ukrainian carpathians abstract the article presents the results of research on the formation conditions and the age of glaciogenic deposits left by the scandinavian ice sheet in the eastern carpathian foreland in its part drained by the dniester river and its tributaries black sea basin these deposits till erratics glaciolacustrine and glaciofluvial sediments preserved only in some places and occurring in the range of altitudes defined by terrace vi early pleistocene and terrace v middle pleistocene are the southernmost traces of the ice sheet in europe they are underlain by fluvial deposits and overlain by loess deposits and locally occur as intraloess layers the following research methods were used geomorphological mapping sedimentological lithological micromorphological palaeopedological and palaeontological analyses as well as luminescence dating the obtained results allowed a reconstruction to be made of the main stages of morphogenesis and the style of the ice sheet advance at its maximum extent defined as the sambor phase the area was glaciated during mis 12 elsterian ii sanian 2 okanian as indicated by the occurrence of a complete middle upper pleistocene loess palaeosol sequence the oldest palaeosol s4 i e sokal mazovian zavadivka soil that developed directly on the glaciogenic deposits or loess l5 is correlated with the holsteinian likhvinian interglacial mis 11

some comparisons of the structure and evolution of the southern appalachian ouachita orogen and portions of the trans european suture zone region abstract many aspects of the tectonic history of the appalachian ouachita orogen and the trans european suture region are similar in a tectonic sense they are geographically linked because at the end of the paleozoic one could travel from texas to poland following a continuous orogenic belt much of each of these orogenic belts is however buried by younger strata and thus geophysical studies are a key element of efforts to better understand them many more geophysical data are needed to provide a comprehensive picture of the deep structure but in several areas new models of the lithospheric structure are emerging in this paper we review some of these models and introduce two new ones for the southern appalachians in addition we explore the implications of these models for the evolution of these orogenic belts drawing attention to similarities and differences in their structure and evolution the appalachian and caledonian orogens represent temporally parallel development along irregular late proterozoic continental margins but the crustal structure is different because of different accretionary elements and complications in the geometry of the original margins lateral transport via thrusting can confuse efforts to tie geologic structures identified on the surface with deep structures for example in the appalachian ouachita orogen the thrust related transport distance for major features such as the blue ridge piedmont sheet and the benton uplift is at least 200 km on a crustal scale deformation in the appalachian ouachita orogen varies greatly in style and intensity in the ouachita orogen the late proterozoic continental margin seems to be preserved while in the northern appalachians crustal scale deformation is intense along the us appalachians the major crustal structure variation is the thin dense crust of avalonia abutting the relatively thick crust of laurentia along the ouachita orogen several large crustal blocks can be identified that are unlike anything seen along the appalachians

sedimentary history of za hajovnou cave moravia czech republic a unique middle pleistocene palaeontological site za hajovnou cave in the javoricko karst moravia czech republic has a rich record of middle pleistocene typical holsteinian flora and fauna dominated by bear ursus deningeri sedimentological geochemical mineralogical geophysical palynological and zoopalaeontological analyses of the sediments along with u th dating of flowstones place the deposits into a numerical timeframe the cave origin dates to a period before the mid miocene badenian transgression the oldest fluvial deposits are lower pleistocene spanning the brunhes matuyama boundary the later terrestrial deposits range from middle pleistocene to holocene the most important result of u th dating is that the main holsteinian senso lato fossil bed can be correlated with mis 9 the lower fossil bed is probably mis 11 and the upper fossil bed mis 5e this represents one of the still relatively few numerically dated holsteinian sites contradicts the global chronostratigraphical correlation table that places the holsteinian only in mis 11 and supports the concept that the holsteinian is not a single unit and likely not confined to a single interglacial c 2013 elsevier ltd and inqua all rights reserved

proterozoic subduction and terrane amalgamation in the southwestern grenville province canada evidence from ultrapotassic to shoshonitic plutonism a late grenvillian 1089 1076 ma subduction regime followed by terrane amalgamation is postulated as the paleoenvironment of a 400 km long belt of potassium rich alkaline and shoshonitic plutons in the central metasedimentary belt of the southwestern grenville province canada emplacement of the plutons postdates the regional metamorphism in the country rock but predates major shear zones that form a structural boundary for the plutonic belt the extent timing and magmatic affinities of the suite delineate the gatineau domain within the current mont laurier terrane of quebec and are compelling evidence for the allochthonous nature of the elzevir terrane and its extension eastward to rideau lake in ontario and northward into the gatineau domain the belt trends northeast the emplacement ages are younger to the southeast and the magmatic affinities are those of island arc ultrapotassic to shoshonitic rocks this is interpreted to reflect the existence of a southeast dipping northeast trending subduction zone beneath the combined elzevir gatineau terrane between 1089 and 1076 ma subsequent to subduction amalgamation of the elzevir terrane to the other terranes formed the central metasedimentary belt which then accreted and collided with the allochthonous polycyclic belt these events provide evidence that the ottawan orogeny commenced at ca 1090 ma in the central metasedimentary belt a modern analogue of this plutonism and its tectonic setting may have been the magmatism and arc continent collision and subduction setting of the sunda are indonesia

late middle pleistocene pollen biostratigraphy in britain pitfalls and possibilities in the separation of interglacial sequences abstract recent work on late middle pleistocene interglacials in britain has shown that sites formerly attributed to the hoxnian include representatives of two different interglacials which have been correlated with oxygen isotope stages 11 and 9 palynology has long been used to characterize and correlate temperate sequences in britain however the quality of the palynological record is considerably better in lacustrine sequences than in fluvial and estuarine sediments the former have longer sequences and higher resolution whereas more rapid deposition in fluvial and estuarine environments leads to sequences representing only fragments of interglacials the latter type of site however is more likely to have multi proxy evidence and to be readily fitted into a stratigraphical framework the problems are reviewed in the light of new work in the west midlands where some of the most complete british late middle pleistocene lacustrine sequences are preserved lacustrine sites here have a strong affinity with hoxnian sites of the type area in east anglia a critical question remains as to whether the two interglacials conflated under the term hoxnian can be separately characterized in terms of their pollen assemblages details of lacustrine sequences in the north birmingham area and east anglia show remarkable similarities perhaps suggesting that the same interglacial is recorded in all of them as many of these sites are thought to be kettle holes or glacially overdeepened basins the first interglacial following the anglian glaciation is the most likely to be represented suggesting that all the lacustrine hoxnian sites might date from ois 11 in areas not glaciated since the anglian interglacials after ois 11 are likely to be represented only by fragmentary non lacustrine sequences difficult if not impossible to separate using palynology alone

a comparison of the receiver structure beneath stations of the canadian national seismograph network three component broadband data from the recently deployed canadian national seismograph network provide a new opportunity to examine the structure of the crust and upper mantle beneath the canadian landmass receiver function analysis is an ideal method to use with this data set as it can provide constraints on the s velocity structure beneath each station of this seismograph network this analysis method is particularly useful in that it provides site specific information i e within 5 15 km of the station low velocity layers can be identified and it is possible to examine structure to upper mantle depths in this study receiver functions were computed for each of the 19 stations that made up the seismograph network in june 1994 five stations sampling a variety of tectonic environments including the appalachian orogen the canadian shield the western canadian sedimentary basin and the cascadia subduction zone were chosen for detailed modelling the results presented here are the first estimates of the s velocity structure beneath these five stations for those stations where comparisons can be made with seismic reflection and refraction results there is excellent agreement in eastern canada simple receiver functions and clear moho ps conversions at most stations indicate a relatively transparent crust and a moho depth of 40 45 km in northwestern canada moho ps phases indicate a crustal thickness of 33 38 km beneath inuvik northwest territories the moho is interpreted as two velocity steps separated in depth by 5 km and an upper mantle low velocity zone is near 47 km depth in western canada the data indicate a mid crustal low velocity zone beneath edmonton the moho of the subducting juan de fuca plate is interpreted at 52 krn depth beneath southern vancouver island several stations exhibiting complex receiver functions warrant further study they include stations at scheffewille quebec in the canadian shield deer lake newfoundland on the boundary of the grenville province and the appalachian orogen and yellowknife northwest territories at the intersection of the churchill and slave provinces and the western plains

on shore amplification of the electric field induced by a coastal sea current abstract numerical techniques for the model approximating the earth by conducting and resistive thin sheets that are underlain by a perfect conductor are used to study the on shore amplification of the electric field induced by the norwegian coastal current the electric field is induced by sea water movement in the earth s magnetic field and decreases away from the sea current however numerical modelling suggests that the electric field is increased significantly on shore due to the conductivity contrast between the sea and the land results of the modelling indicate the significant in land decrease of the electric field anomaly controlled by the adjustment distance depending on the conductance of the first layer and the transverse resistance of the second one the coastal electric field anomaly ranges up to 10 mv km 1 which is large enough to be measured by 5 10 km long receiving antenna

heterogeneous structure around the jemez volcanic field new mexico usa as inferred from the envelope inversion of active experiment seismic data summary we analyse active experiment seismic data obtained by the 1993 jemez tomography experiment jtex programme to elucidate the heterogeneous structure of the jemez volcanic field which is located at the boundary between the colorado plateau and the rio grande rift using a single isotropic scattering assumption we first calculate the envelope green s functions for the upper and lower crust and the uppermost mantle by fitting the theoretical envelopes with the observed three component data we estimate depth dependent features of the scattering coefficients around valles caldera we estimate the ratios of scattering coefficients rather than scattering coefficients themselves because of the uncertainty of the seismic efficiency of the explosive sources and knowledge of absolute site amplification factors the strongest scattering coefficients are observed at a shallow depth beneath the valles caldera this is considered to be related to the complex structure caused by two episodes of caldera formation and the ensuing resurgent uplift in the caldera etc the depth dependent characters of the scattering coefficients for the colorado plateau and the rio grande rift are similar to each other a transparent upper crust and a heterogeneous lower crust small and large scattering coefficients respectively however the scattering coefficients beneath the rio grande rift are several times larger than those beneath the colorado plateau depths of the lower crust and the moho boundary beneath the rio grande rift are shallower than those of the colorado plateau from their geological settings and other geophysical results around the region we infer that the larger scattering coefficients of the rift are associated with rift formation and volcanic activity such as magma ascent from the upper mantle to the crust

river terrace sequences templates for quaternary geochronology and marine terrestrial correlation fluvial sequences particularly terrace staircases represent archives of quaternary palaeoclimatic fluctuation and can serve as stratigraphical frameworks for geochronology and for correlation with other depositional environments in particular the global marine oxygen isotope record fluvial lithostratigraphical frameworks also provide contexts for records from fossils and artefacts of faunal evolution and human occupation conversely both records can be means of relative dating of riverine sequences three fluvial sequences are examined as case studies first is the severn avon system in the english midlands which has biostratgraphical evidence and an amino acid geochronology together with marker inputs from three different glaciations the somme sequence of northern france famous for its palaeolithic artefact assemblages again has biostratigraphy and an amino acid geochronology and has also been dated with reference to overlying loess palaeosols sequences the fluvial terraces of the river arun the final case study lack dating evidence but are interspersed within the sussex raised beach staircase although various lines of evidence suggest that the rivers discussed have formed terraces in response to climatic fluctuation an intriguing difference is that interglacial sediments occur at the bases of terrace formations in the severn avon whereas in the somme they occur at the tops of sequences beneath loessic overburden

numerical 230th u dating and a palynological review of the holsteinian hoxnian interglacial abstract earth scientists increasingly consider the holsteinian interglacial and mis 11 as synonyms despite the limited number of numerical dates and ambiguous stratigraphic and palynological correlation with the numerical marine isotope timescale hence we present new tims 230th u dates from two fen peat layers of the holsteinian reference site at bossel in northern germany and re evaluate published numerical data from two sites with hoxnian deposits in england a new method for the calculation of methodically controlled minimum 230th u ages mcma was developed the synopsis of the 230th u dates allows a correlation of both the holsteinian and hoxnian interglacials to mis 9 this correlation is supported by supplementary 230th u dates of fen peat from several pre eemian but non holsteinian sites in germany there is palynological evidence for a reliable correlation between precisely investigated and numerically dated holsteinian deposits in poland germany england sw ireland and france an apparently contradictory palynological correlation from the french central massif is discussed

composition of the crust in the grenville and appalachian provinces of north america inferred from v p v s ratios we use the ratios between p and s wave velocities vp vs derived from seismic refraction data to infer the composition of the crust in the grenville and the appalachian provinces of north america the crust exhibits vp vs increasing with depth from 1 64 to 1 84 there is a clear distinction between the grenville province average vp vs 1 81 and the appalachian province average vp vs 1 73 which persists at all depths the boundary between these provinces is east dipping extending for 100 km east of the champlain thrust in the appalachian province the increase in vp vs ratios with depth from 1 67 to 1 74 0 02 may reflect a normal decrease of silica content in the continental crust in the grenville province beneath the central granulite terrane an anomalous vp vs ratio of 1 82 0 02 is observed extending to a depth of 10 km this correlates with the abundance of ca plagioclase in the marcy anorthosite at greater depth 15 20 km where seismic lamination and high electrical conductivity is observed vp vs is 1 84 0 02 and correlates with the tahawus complex a layered mafic intrusion within the 25 km thick lower crust of the grenville province the vp vs is 1 84 0 02 and p velocity is 7 0 0 1 km s which are typical for plagioclase bearing rocks gabbro norite the high vp vs ratio in the grenville province has not been reported in crust of any other age since the grenville province contains 75 of the world s known anorthosites high vp vs ratio is related to high plagioclase we suggest that the composition of the grenville lower crust was significantly modified by the emplacement of the anorthosites in the mid proterozoic

crustal structure of the grenville province in southeastern labrador from refraction seismic data evidence for a high velocity lower crustal wedge the crustal structure of the eastern grenville and makkovik provinces was determined using two onshore offshore refraction seismic lines of the lithoprobe eastern canadian shield onshore offshore transect ecsoot a gravity high in the hawke river terrane correlates with increased p wave velocities in the upper 30 km of the crust 6 2 6 7 km s in the upper and middle crust and 6 9 7 1 km s below which we interpret as structure inherited from the labradorian orogen velocities in the adjacent groswater bay terrane are 6 0 6 55 km s in the upper and middle crust and 6 6 6 95 km s in the lower crust the entire grenville crust is underlain by a 15 20 km thick high velocity lower crustal hvlc wedge consisting of an upper layer 7 1 7 4 km s and a lower layer 7 6 7 8 km s the hvlc wedge is interpreted as an underplated layer formed during iapetan rifting this interpretation is based on the correlation with the 615 ma long range dykes onshore and the eastward termination of the wedge at the cartwright

differentiation of the british late middle pleistocene interglacials the evidence from mammalian biostratigraphy abstract acknowledgement of the climatic complexities of the marine oxygen isotope 18o record has inspired fresh investigations into methods of identifying and separating interglacial deposits on land biostratigraphical analysis of fossil mammalian assemblages particularly those from long fluvial sequences has proved to be a uniquely valuable technique in the differentiation of the various temperate episodes of the late middle pleistocene in britain thereby enabling a sequence of diagnostic mammalian assemblage zones to be established the scheme has provided an important means of correlation between geographically distant localities and between different types of depositional environment using mammalian biostratigraphical information this paper explores the evidence for three post anglian interglacials prior to the last ipswichian interglacial correlated with stages 11 9 and 7 of the oxygen isotope record and presents the case for the recognition of much smaller scale environmental and climatic oscillations within these interglacials possibly corresponding to marine isotopic substages

revision of the late middle pleistocene stratigraphy and palaeoclimate in poland abstract the aim of this paper is a critical verification of the late middle pleistocene stratigraphy in poland in connection with stratigraphical schemes in the neighbouring countries although a terrestrial record of the middle pleistocene is almost complete in western and southern europe it is full of gaps in central and eastern europe eight key sites in poland and one in belarus were selected to compile environmental and palaeoclimate data for a revised stratigraphy from the termination of mis 12 to mis 6 and the chronology was based on correlation with oxygen isotope stratigraphy and osl ages the late middle pleistocene record starts with the holsteinian lake sequences some of which have been initiated already at the end of mis 12 persisted through mis 11 and terminated in mid mis 10 in the examined sites mis 11 is represented also by deposits of meandering rivers in a temperate climate in contrast there is no evidence for deposition in most of mis 10 and in mis 9 a warmer and presumably wet episode at the beginning of mis 8 lead to local erosion followed by development of small lakes modest ice sheet advance into central europe occurred in the second part of mis 8 as reflected by a till glaciofluvial and glaciolacustrine deposits and presumably also by permafrost and ice wedges in western belarus mis 7 seems to have been generally warm and wet when small lakes and meandering rivers could develop such mild conditions were interrupted with cool and probably drier episodes when braided rivers and limited pedogenesis occurred saalian ice sheet cover of central europe in mis 6 was widespread but even more importantly in this stage periglacial environments were dominant as shown by continuous permafrost intensive aeolian activity and development of ice wedges and involutions braided rivers developed during short wetter intervals

crustal structure of the southeastern grenville province northern new york state and eastern ontario the grenville province exposes an oblique cross section through mid lower crustal lithologies that were pervasively deformed and subjected to regional thermal overprinting during the grenvillian orogeny 1 1 ga the southeastern grenville province is divided into two subterranes by the carthage colton mylonite zone a 110 km long lineament characterized by intense ductile shear and igneous intrusion which separates the amphibolite facies metasediments of the central metasedimentary belt to the west from the granulite facies metaplutonics of the central granulite terrane to the east the recognition of distinct lithotectonic domains separated by zones of intense ductile shear in the grenville province raises questions concerning the deep structure of these subterranes and in particular the means by which the mid lower crustal rocks exposed in the grenville province were emplaced seismic refraction wide angle reflection data were acquired to investigate the deep structural interrelationships within the southeastern grenville province a travel time inversion for velocity and interface depth was applied to the seismic data together with constraints from amplitude modeling to produce a seismic velocity model of the crust in the southeastern grenville province in the central metasedimentary belt the upper crust is characterized by velocities in the range 6 3 6 4 km s and a poisson s ratio of 0 26 0 01 which are attributed to quartzofeldspathic rocks farther east in the central granulite terrane upper crustal velocities of 6 55 km s and a poisson s ratio of 0 28 0 01 are associated with the marcy anorthosite the seismic homogeneity of the upper crust in the region of the carthage colton mylonite zone suggests that this boundary is a shallow feature limited to the upper 2 3 km of the crust the deep crustal structure of the southeastern grenville province is characterized by two discrete and laterally discontinuous seismic interfaces in the central metasedimentary belt the top of the lower crust is delineated by an eastward dipping interface at 24 28 km depth in the central granulite terrane prominent en echelon reflections referred to as the tahawus complex form a gently arched dome at 17 22 km depth interpretation of the tahawus complex as a zone of layered mafic cumulates is supported by its high velocity 7 1 km s and poisson s ratio 0 27 0 02 the lower crust is characterized by a velocity of 7 0 7 2 km s and an anomalously high poisson s ratio of 0 30 0 02 which are representative of pyroxene garnet granulites in contrast velocities of 6 8 7 0 km s are modeled beneath the central granulite terrane and appear to signify a lateral change in composition the moho lies at 44 45 km depth and is characterized by pronounced en echelon reflection segments suggesting compositional interlayering around the crust mantle boundary the velocity of the upper mantle is 8 0 8 2 km s an anomalous upper mantle layer with a reversed velocity of 8 6 km s dips eastward from 50 to 60 km depth beneath the southeastern grenville province our results indicate that remnants of magmatic intrusions that mobilized and thickened the crust during the grenvillian orogeny are preserved in the mid lower crust as a layered cumulate body tahawus complex and in the upper mantle as an eclogitic lens possibly delaminated from the overthickened crust during uplift of the southeastern grenville province

the seismic velocity structure of the newfoundland appalachian orogen the deep structure of the newfoundland appalachian orogen is investigated by analyses of three intersecting seismic refraction wide angle reflection profiles which traverse the gander and dunnage zones or central mobile belt of newfoundland a simultaneous travel time inversion for velocity and interface was applied to the in line seismic refraction wide angle reflection data and constrained by synthetic amplitude models the results of the modeling procedure show a subhorizontally layered crust with upper crustal velocities ranging from 5 4 to 6 2 km s a midcrustal velocity of 6 25 6 35 km s and a lower crustal velocity of 6 7 0 2 km s the top of the lower crust is marked by a series of prominent reflections between 18 and 23 km depth which suggest a complex layered velocity interface strong laterally coherent moho reflections indicate a sharp crust mantle transition at 35 3 km the uppermost mantle has a velocity of 8 0 0 2 km s and a reflecting horizon at 55 km depth suggests an increase to velocities approaching 8 5 km s normal moveout corrections applied to fan profiles provide constraining evidence for the reflecting horizon at the top of the lower crust and laterally continuous moho reflections at 11 12 s two way travel time comparisons with a coincident deep seismic reflection profile show that the refraction and reflection mohos match to better than 2 3 km bulk poisson s ratios of 0 23 0 24 for the whole crust calculated from pmp sms travel times suggest a crust dominated by quartzofeldspathic lithologies and a notable absence of voluminous mafic additions to the lower crust the absence of a deep crustal root coupled with the bulk intermediate composition inferred for the lower crust from the seismic refraction wide angle data implies that the crust beneath central newfoundland has undergone multiple periods of reactivation and equilibration following successive orogenic episodes

cooling and inferred uplift erosion history of the grenville orogen ontario constraints from 40ar 39ar thermochronology stepwise 40ar 39ar degassing experiments of 57 mineral separates of hornblende muscovite biotite and perthitic microcline have been used in conjunction with petrologic observations to place regional constraints on the postmetamorphic cooling and the inferred uplift and erosion history of the grenville orogen in ontario the 40ar 39ar data support an interpretation of slow nearly uniform cooling 1 4 c m y from temperatures of 500 c to below 150 c in the central gneiss belt cgb hornblendes cooled through ar closure between 930 and 1025 ma whereas in the central metasedimentary belt cmb hornblendes record the following range in 40ar 39ar cooling ages 1104 ma in the frontenac terrane 1007 1067 ma in the sharbot lake terrane 919 1026 ma in the elzevir terrane and 972 ma in the central metasedimentary belt boundary zone regional uplift erosion rates of 0 03 0 14 km m y have been estimated for the grenville orogen in ontario based on the 40ar 39ar data a model retrograde p t path for rocks of the cgb and an upper time constraint provided by flat overlying cambrian and ordovician sediments these erosion rates are consistent with rates estimated for other proterozoic or archean granulite terranes but are an order of magnitude slower than active orogens such as the alps and himalayas a regular variation in hornblende 40ar 39ar cooling ages is observed in rocks that traverse highly strained often mylonitic shear zones that separate the four major terranes of the cmb the pattern of 40ar 39ar ages is interpreted to reflect late tectonic extension consistent with field observations in the central metasedimentary belt boundary zone and elsewhere in the cmb up to 13 km of vertical displacement is inferred for some rocks in the cmb between the time they cooled below closure to argon diffusion in hornblende 500 c and their exposure at the surface 25 c

climate and environments during marine isotope stage 11 in the central iberian peninsula the herpetofaunal assemblage from the acheulean site of aridos 1 madrid abstract the interglacial episodes of the quaternary period are currently the focus of a great deal of attention within the scientific community primarily because they can help us to understand how the climate of the current interglacial may have evolved without human intervention and to assess the impact of these climate changes on ecological systems in the central iberian peninsula the archaeological site of aridos 1 arganda madrid with numeric dates of 379 7 45 ka obtained by aar for the upper part of the sedimentological unit of arganda i in combination with the evolved state of the small mammals has been chronologically attributed to marine isotope stage mis 11 given the diversified faunal assemblages delivered by the 1976 excavations aridos 1 is probably one of the best terrestrial candidates for an understanding of the climatic and environmental conditions that prevailed in central spain during the mis 11 interglacial in consequence the fossil amphibians and squamate reptiles stored in the collections of the museo arqueologico nacional of madrid have been newly described and quantified in order to apply the mutual climatic range and habitat weighting methods for estimating quantitative data the mediterranean climate is shown to have been warmer and wetter than today in central spain during mis 11 with the mean annual temperature 1 7 c higher and mean annual precipitation 223 9 mm higher than at present the monthly climatic reconstruction shows differences in the distribution of precipitation over the course of the year with more abundant precipitation during the winter months at the beginning of spring and at the end of fall from october to march and less precipitation than today during the summer months and at the end of spring from may to august suggesting stronger rainfall seasonality between winter and summer than currently occurs such climate reconstruction is consistent with other european mis 11 paleoclimatic records the paleoenvironmental reconstruction based on the herpetofaunal assemblage suggests a patchy landscape with a large representation of dry meadows scrubland and rocky habitats together with well evidenced aquatic habitats such open environments during a warm and humid forestal period are seen to be connected with the location of the site in a large river valley where open vegetation would have been partly initiated and certainly maintained by the grazing browsing trampling and tree felling activities of large mammals

a new calibration of seismic velocities anisotropy fabrics and elastic moduli of amphibole rich rocks 1 a large portion of the middle to lower crust beneath the continents and oceanic island arcs consists of amphibolites dominated by hornblende and plagioclase we have measured p and s wave velocities vp and vs and anisotropy of 17 amphibole rich rock samples containing 34 80 vol amphibole at hydrostatic pressures p up to 650 mpa combined petrophysical and geochemical analyses provide a new calibration for mean density average major element contents mean vp p and vs p coefficients intrinsic vp and vs anisotropy poisson s ratios the logarithmic ratio rs p and elastic moduli of amphibole rich rocks the vp values decrease with increasing sio2 and na2o k2o contents but increase with increasing mgo and cao contents the maximum 0 38 0 40 km s and minimum s wave birefringence values occur generally in the propagation direction parallel to y and normal to foliation respectively amphibole plays a critical role in the formation of seismic anisotropy whereas the presence of plagioclase quartz pyroxene and garnet diminishes the anisotropy induced by amphibole crystallographic preferred orientations cpos the cpo variations cause different anisotropy patterns illustrated in the flinn diagram of vp x vp y vp y vp z plots the results make it possible to distinguish in terms of seismic properties the amphibolites from other categories of lithology such as granite granodiorite diorite gabbro diabase felsic gneiss mafic gneiss eclogite and peridotite within the earth s crust hence amphibole aligned by dislocation creep anisotropic growth or rigid body rotation is the most important contributor to the seismic anisotropy of the deep crust beneath the continents and oceanic island arcs which contains rather little phyllosilicates such as mica or chlorite

tectonic and climatic control on terrace formation coupling in situ produced 10be depth profiles and luminescence approach danube river hungary central europe abstract the terrace sequence of the hungarian part of the danube valley preserves a record of varying tectonic uplift rates along the river course and throughout several climate stages to establish the chronology of formation of these terraces two different dating methods were used on alluvial terraces exposure age dating using in situ produced cosmogenic 10 be and luminescence dating using monte carlo approach to model the denudation rate corrected exposure ages in situ produced cosmogenic 10 be samples originated from vertical depth profiles enabled the determination of both the exposure time and the denudation rate post ir irsl measurements were carried out on k feldspar samples to obtain the ages of sedimentation the highest terrace horizon remnants of the study area provided a best estimate erosion corrected minimum 10 be exposure age of 700 ka we propose that the abandonment of the highest terrace of the hungarian danube valley was triggered by the combined effect of the beginning tectonic uplift and the onset of major continental glaciations of quaternary age around mis 22 for the lower terraces it was possible to reveal close correlation with mis stages using irsl ages the new chronology enabled the distinction of tiib 90 ka mis 5b c and tiiia 140 ka mis 6 in the study area surface denudation rates were well constrained by the cosmogenic 10 be depth profiles between 5 8 m ma and 10 0 m ma for all terraces the calculated maximum incision rates of the danube relevant for the above determined 700 ka time span were increasing from west

anomalous seaward dip of the lithosphere asthenosphere boundary beneath northeastern usa detected using differential array measurements of rayleigh waves summary rayleigh wave phase velocities and azimuth anomalies in the period range of 30 100 s are measured for a set of four triangular arrays of broad band seismometers in coastal northeastern usa this is a region in which a strong upper mantle slow shear velocity anomaly a new england anomaly crosses the continental margin earthquakes from a wide range of directions are used to detect the variation of parameters with azimuth of propagation no lateral heterogeneity in phase velocity is detected at these periods between stations at the centre and the edge of the anomaly however large 10 20 per cent azimuthal variations occur and have a cos 1 dependence which is indicative of a dipping structure in the upper mantle corresponding azimuth variations with a magnitude of 5 are also detected this behaviour is consistent with a southeasterly n150 e dip of the lithosphere asthenosphere boundary beneath new england this dip is associated with the shoaling of the new england anomaly beneath the adirondack mountains west of the array it is opposite to the dip associated with lithospheric thickening toward the interior of the craton

some results of cocorp seismic reflection profiling in the grenville age adirondack mountains new york state cocorp deep seismic reflection profiling in the adirondack mountains of northern new york state has revealed a prominent zone of layered reflectors in the lower crust of the east central adirondacks the strong layered reflectors here termed the tahawus complex occur between 18 and 26 km depth beneath the sparsely reflective granulite grade surface terrane which has been uplifted from depths greater than 20 km the tahawus complex apparently represents layered rocks of some type in the lower crust of the adirondacks possibilities include gneissic layering cumulate igneous layering a layered sill complex and underthrust sedimentary strata the tahawus complex may be spatially coincident with a previously detected high conductivity zone in the lower crust suggesting that either unusual mineralogies or interstitial electrolytes are present in the tahawus complex in contrast to layered reflections discovered in the lower crust of the east central adirondacks and southeast of the adirondacks cro

abrupt climate events 500 000 to 340 000 years ago evidence from subpolar north atlantic sediments subpolar north atlantic proxy records document millennial scale climate variations 500 000 to 340 000 years ago the cycles have an approximately constant pacing that is similar to that documented for the last glacial cycle these findings suggest that such climate variations are inherent to the late pleistocene regardless of glacial state sea surface temperature during the warm peak of marine isotope stage 11 mis 11 varied by 0 5 to 1 c less than the 4 to 4 5 c estimated during times of ice growth and the 3 c estimated for glacial maxima coherent deep ocean circulation changes were associated with glacial oscillations in sea surface temperature

exploration in the shetland faeroe basin using densely spaced arrays of ocean bottom seismometers recent exploration activity in the peripheral regions of the shetland faeroe basin offshore northwest scotland has led to the discovery of some of the largest oil reserves on the united kingdom uk continental shelf we present results from two ocean bottom seismometer profiles acquired by mobil north sea ltd across the center of the shetland faeroe basin these data provide a powerful tool for delineating long wavelength velocity variations and thus have potential for reducing the nonuniqueness associated with conventional seismic exploration methods analysis of the first arrival traveltime data using both forward and inverse ray based techniques produces a well constrained velocity depth model of the basin fill we estimate that the uncertainty in the velocity structure is 5 from a series of trial and error perturbations applied to the final models the velocity structure of the faeroe basin has three principal layers 1 a near surface layer with velocities in the range 1 6 to 2 2 km s 2 a 3

modeling wide angle seismic data for crustal structure southeastern grenville province a modeling methodology for obtaining two dimensional 2 d crustal structure from wide angle seismic data is applied to data from the southeastern grenville province pre modeling steps include 1 assignment of arrival pick uncertainties for appropriate data fitting and weighting using an empirical relationship based on signal to noise ratio 2 using a modified form of travel time reciprocity to avoid unreasonable levels of model heterogeneity and 3 identifying data unsuitable for 2 d modeling the goal of the travel time inversion amplitude modeling approach is to obtain a minimum structure and minimum parameter model that takes into account both horizontal and vertical variations in the resolution of typical wide angle data each step of a layer stripping procedure involves a series of inversions in which a one dimensional or simple starting model is improved with additional velocity and or interface nodes until a satisfactory trade off between travel time fit parameter resolution and complete ray coverage of all source receiver pairs is achieved using zero vertical velocity gradient layers and head waves during preliminary first arrival inversion can 1 decrease the number of intermediate models 2 allow greater lateral heterogeneity to be imaged and 3 simplify incorporation of amplitude modeling constraints into the final model using amplitude distance curves allows quantitative modeling of the relative amplitude and offset variations of phases discrepancies between observed and calculated reflection amplitudes are used to infer fundamental non step like velocity changes at layer boundaries later arrivals due to unresolved velocity anomalies are modeled using reflecting segments that float within the model without an associated velocity structure these reflectors provide a spatial image like that obtained from vertical incidence reflection data as opposed to a velocity image the model of grenville crustal structure is more detailed than a model obtained from a previous interpretation of the data and includes elements analogous to those imaged in nearby deep reflection data a crustal scale zone of wide angle reflectors with an average easterly apparent dip of 13 defines a major grenvillian terrane boundary

u series dating of hoxnian interglacial deposits at marks tey essex england a u th dating study was carried out on the authigenic carbonate component of interglacial lake sediments at marks tey essex england isochron methods were necessary because of the presence of non carbonate detritus calculated dates around the limit of the u th method were obtained for two horizons error limits were determined by monte carlo sampling from the normal distributions of errors in the isotope ratios comparison of the resulting empirical distribution functions with the marine oxygen isotope time scale indicates with 87 confidence that the marks tey sediments correlate with ois 11 or some older stage as the marks tey deposits rest without stratigraphical break on anglian till and can be firmly correlated with the hoxnian interglacial type site at hoxne suffolk england this result implies that the anglian glaciation took place in ois 12 acid the hoxnian stage of the british chronostratigraphy commenced in ois 11 copyright c 1999 john wiley sons ltd

sw grenville province canada the case against post 1 4 ga accretionary tectonics abstract seven accretionary sutures formed between 1 16 and 1 03 ga have been identified by different authors in the ontario quebec adirondack oqa segment of the mesoproterozoic grenville orogen in canada with one exception the inferred accretionary terrane boundaries lie within or at the margins of the central metasedimentary belt cmb located between the central gneiss belt and the adirondack highlands central granulite terrane however geological geochronological and petrological data suggest that the grenville orogen on both sides of the proposed terrane boundaries sutures preserves a common 1 4 1 03 ga tectonomagmatic history inconsistent with its origin as a post 1 4 ga collage of exotic tectonic blocks features which straddle the proposed 1 16 1 03 ga sutures from the central gneiss belt via the adirondack highlands to the mauricie area include 1 mesoproterozoic continental crust 1 5 1 4 ga forming the host and or basement to younger magmatic and supracrustal suites 2 a 1 35 1 3 ga continental arc remnants of which occur from the cmb boundary zone cmbbz in ontario to the appalachians in the united states built on the 1 5 1 4 ga continental crust 3 intrusions of 1 17 1 13 ga age in the central gneiss belt mafic suite and the adirondack highlands and their quebec extension amcg suite i e anorthosite massifs and related granitoids 4 relics of 1 18 1 14 ga sedimentary basins in the northwestern cmb and the mauricie area we propose that an alternative model can adequately account for the observed geology of this part of the grenville orogen wherein the rocks of the oqa segment were part of an andean type margin between 1 4 and 1 2 ga at 1 35 1 3 ga a continental magmatic arc was built upon the southeastern margin of laurentia represented by the 1 5 1 4 ga mesoproterozoic continental crust the arc split at 1 3 ga forming an ensialic back arc basin relics of which now occur in the northwestern part of the cmb and the back arc basin was flanked to the southeast by an active 1 28 1 25 ga arc collision between the laurentian margin and another continent amazonia occurred at 1 2 ga resulting in closure of the back arc basin and initiation of thrusting along the cmbbz post collisional lithospheric shortening led to convective removal of thickened subcontinental lithosphere upper mantle melting and extension of the overlying crust resulting in widespread magmatic activity at 1 17 1 13 ga including emplacement of the amcg massifs crustal extension generated sedimentary basins now represented by the st boniface sediments in the mauricie area 1 18 to between 1 15 and 1 09 ga and the penecontemporaneous flinton group in the northwestern cmb renewed post collisional granulite facies shortening commenced at 1 12 ga manifested as nappes in the central gneiss belt and thrusting in the mauricie area continued post collisional shortening at 1 08 1 05 ga was more localised resulting in reactivation of thrusting in the cmbbz and initiation of the kinematically compatible tawachiche shear zone along the eastern border of the quebec extension of the adirondack highlands the characteristics of the oqa segment of the grenville orogen can all be accounted for in the context of 1 a 1 4 1 2 ga southeast facing andean type margin to a laurentian upper plate associated with northwest dipping subduction 2 continental collision at 1 2 ga and 3 subsequent continued post collisional shortening without invoking accretion of exotic terranes between 1 4 and 1 0 ga

a contribution towards the palynostratigraphical classification of the middle pleistocene in central europe the pollen record of the neualbenreuth maar northeastern bavaria germany abstract palaeoecological evidence of intra saalian warm stages in central europe which was strongly affected by glacial and periglacial processes during the major middle and late pleistocene cold periods is ambiguous so far recently the first continuous sedimentary sequence of central europe containing the saalian complex mis 8 6 with the eemian interglacial in stratigraphic superposition was recovered from the newly discovered neualbenreuth maar ne bavaria here we present palynological results from this record allowing us to critically discuss the available biostratigraphical evidence of alternating intra saalian warm cold intervals from central europe the new pollen record from the neualbenreuth maar comprises a continuous record of vegetation and climate changes encompassing four warm stages and five cold periods the dominance of cold and dry tolerant herbs and the sparse representation of pioneer trees and shrubs during most parts of the sequence indicate open landscapes of steppe to woody steppe character typical of late middle and late pleistocene glacial periods in central europe the pollen assemblages of the warm stage in the upper part of the core clearly support its correlation with the eemian interglacial the three pre eemian warm stages represent terrestrial analogues of the marine isotope stages mis 7e 7c and 7a during each of these intervals forests were established but the reduced abundances and lower diversity of thermophilous and sub oceanic elements in comparison to the eemian attest to a weak interglacial character each of these interglacials shows a similar vegetation succession and only minor differences in the vegetation composition the intervening stadial periods represent a strong mis 7d and a moderate mis 7b climate deterioration respectively the vegetation and climate succession during the saalian glacial interglacial complex of neualbenreuth is broadly in line with the respective palynological signature from the velay record french massif central and the hoogeveen interstadial the netherlands in contrast there is only limited correspondence with most pollen records from northern and southern central europe which were hitherto classified as mis 7

lith5 0 a revised crustal model for canada based on lithoprobe results summary during the last 15 yr numerous seismic refraction experiments have been conducted overthe canadian landmass most as part of the lithoprobe initiative the new results providethe basis for revising existing global models of crustal structure e g crust5 1 mooney et al 1998 which do not incorporate the new lithoprobe data the crustal model discussedhere lith5 0 combines the lithoprobe and crust5 1 data to provide better constraints oncrustal structure in canada the objectives of the study are to 1 compile available new datainto a single consistent database of crustal thickness and velocity including the uppermostmantle pn velocity and 2 to construct a revised 5 5 crustal model of the canadianlandmass in a format that is generally compatible with existing global models the lithoproberesults suggest a 5 5 km average root mean square rms crustal thickness difference betweenlith5 0andcrust5 1 evenwiththeincorporationofthenewdata thegeographiccoveragein north and central canada remains sparse the new model does not explicitly incorporategeological constraints but instead relies on spherical spline interpolation for extrapolatingvalues into regions that lack control to illustrate the implications of this new crustal model we use lith5 0 to correct for the isostatically compensated crustal heterogeneity in order toobtain improved estimates of the dynamic surface topography the latter provides importantconstraints on the density structure of the uppermost mantle

isotopic constraints on emplacement age of anorthositic rocks of the marcy masiff adirondack mts new york the igneous emplacement age of anorthositic rocks comprising the marcy massif have been constrained by fixing minimum and maximum ages for their intrusion minimum ages have been fixed by a u pb dating of cores of air abraded zircons from the anorthosite 1113 ma b u pb dating of baddeleyite within the anorthosite 1087 ma c u pb dating of baddeleyite from an olivine metagabbro crosscutting marcy massif anorthosite 1109 ma d u pb zircon dating of jotunitic rocks crosscutting the marcy anorthosite massif 1143 pm 31 ma maximum emplacement ages are based upon a sheets of anorthositic rock crosscutting mangeritic charnockitic gneiss dated by u pb zircon at 1125 pm 10 ma 1134 pm 4 ma and 1135 pm 43 ma and b anorthosite related pyroxenite dikes crosscutting mangerite that contains xenoliths of identical pyroxenite these results constrain emplacement of the marcy anorthosite to 1113 1138 ma with the most probable age in the interval 1125 1135 ma this time of in