respective influences of iod and enso on the tibetan snow cover in early winter using reanalysis data and snow cover data derived from satellite observations respective influences of indian ocean dipole iod and el nino southern oscillation enso on the tibetan snow cover in early winter are investigated it is found that the snow cover shows a significant positive partial correlation with iod in the pure positive iod years with no co occurrences of el nino negative geopotential height anomalies north of india are associated with warm and humid southwesterlies to enter the plateau from the bay of bengal after rounding cyclonically and supply more moisture this leads to more precipitation more snow cover and resultant lower surface temperature over the plateau these negative geopotential height anomalies north of india are related to the equivalent barotropic stationary rossby waves in the south asian wave guide the waves can be generated by the iod related convection anomalies over the western central indian ocean in contrast in the pure el nino years with no co occurrences of the positive iod the anomalies of moisture supply and surface temperature over the plateau are insignificant suggesting negligible influences of enso on the early winter tibetan snow cover further analyses show that enso is irrelevant to the spring early summer tibetan snow cover either whereas the iod induced snow cover anomalies can persist long from the early winter to the subsequent early summer

structural setting and age of the partridge island block southern new brunswick canada a link to the cobequid highlands of northern mainland nova scotia the partridge island block is a newly identified tectonic element in the saint john area of southern new brunswick located south of and in faulted contact with proterozoic and cambrian rocks of the ganderian brookville and avalonian caledonia terranes it includes the lorneville group and tiner point complex the lorneville group consists of interbedded volcanic and sedimentary rocks subdivided into the taylors island formation west of saint john harbour and west beach formation east of saint john harbour a sample from thin rhyolite layers interbedded with basaltic flows of the taylors island formation at sheldon point yielded a late devonian early carboniferous u pb zircon age of 358 9 6 5 ma petrological similarities indicate that all of the basaltic rocks of the taylors island and west beach formations are of similar age and formed in a continental within plate tectonic setting west of saint john harbour basaltic and sedimentary rocks of the taylors island formation are increasingly deformed and mylonitic to the south and in part tectonically interlayered with mylonitic granitoid rocks and minor metasedimentary rocks of the tiner point complex based on magnetic signatures the deformed rocks of the tiner point complex can be traced through partridge island to the eastern side of saint john harbour where together with the west beach formation they occupy a thrust sheet above a redbed sequence of the mid carboniferous balls lake formation the tiner point complex includes leucotonalite and aegirine bearing alkali feldspar granite with a type chemical affinity and early carboniferous u pb zircon ages of 353 6 5 7 and 346 4 0 7 ma respectively based on similarities in age petrological characteristics alteration iron oxide copper gold iocg type mineralization and deformation style the partridge island block is correlated with late devonian early carboniferous volcanic sedimentary plutonic rocks of the cobequid highlands in northern mainland nova scotia deformation was likely a result of dextral transpression along the cobequid chedabucto fault zone during juxtaposition of the meguma terrane

late devonian early carboniferous volcanism in western cape breton island nova scotia the fisset brook formation of western cape breton island and its equivalents at macmillan mountain and the north baddeck river are examples of late devonian and early carboniferous volcanic sequences associated with the formation of post acadian successor basins in the northeastern appalachians they consist of bimodal basalt rhyolite suites interbedded with alluvial fan lacustrine and rare fluvial sediments the earliest volcanic products are rhyolites and somewhat evolved basalts associated with coarse sediments followed by tholeiitic to transitional basalt flows interlayered with lacustrine type deposits geochemical studies on the fisset brook formation indicate extensive remobilization of alkalies ca rb and sr making these elements inappropriate for determining tectonic setting or magmatic affinity use of less mobile elements ti nb y and zr suggests that the basalts are tholeiitic and that the apparent alkalinity of the type section lavas is a result of alteration we conclude that volca

ensemble simulations of eurasian snow depth anomalies and their influence on the summer asian monsoon the effect of springtime surface conditions over eurasia on the monsoon circulation is addressed by using several simulations with the model used by the european centre for medium range weather forecasts ecmwf the simulations have been specially designed to investigate whether the eurasian snow anomaly is a passive response to the tropical forcing implying that the ultimate relationship exists only between the el nino southern oscillation enso and the monsoon as suggested by previous studies or plays an active independent role in the monsoon modulation preliminary results suggest that the eurasian snow depth is probabilistically predictable and that it does influence the seasonal mean monsoon independently of the enso phase therefore proper observations and simulations of the eurasian snow field can provide an additional and independent contribution to monsoon prediction

minas fault zone late paleozoic history of an intra continental orogenic transform fault in the canadian appalachians abstract the minas fault zone mfz defines the boundary between the avalon and meguma terranes in the canadian appalachians and is exposed in mainland nova scotia and southern new brunswick these terranes originated along the gondwanan margin but had accreted to laurentia by the middle devonian the surface trace of the mfz is adjacent to the southern margin of the latedevonian permian maritimes basin the late devonian late carboniferous evolution of the mfz involves several episodes of oblique dextral shear that resulted in basin formation and inversion and at various times the zone was the focus of magmatism regional fluid flow and mineralization in the late devonian early carboniferous asymmetric rifting accompanied by dextral shear produced two coeval sequences the horton group which is dominated by continental clastic strata and the fountain lake group which consists predominantly of bimodal volcanic rocks that overlie high level plutons emplaced along active shear zones the overall tectonic environment may have been dominated by dextral transtension along the southern margin of laurentia which corresponded with the northern flank of the rheic ocean a major change in the evolution of the minas fault zone occurred in the late mississippian early pennsylvanian and produced the e w chedabucto fault clockwise rotation of pre existing structures local zones of transtension and transpression as well as regional fluid flow and extensive mineralization this major change may reflect the onset of laurentia gondwana oblique collision the effects of which continued into the latest carboniferous with coeval development of flower structures and pull apart basins in zones of local transpression and transtension

bulk organic δ13c and c n ratios as palaeosalinity indicators within a scottish isolation basin microfossils in isolation basin sediments are frequently used to reconstruct sea level change but preservation problems and non analogue situations can limit their usefulness here we investigate the potential of stable carbon isotopes 13c and c n ratios from bulk organic matter as an alternative proxy of salinity within isolation basin sediments from a basin in northwest scotland within the holocene sediment 13c and c n are determined largely by the mean weighted values of the predominant source of the organic material analysis of modern materials and comparison with the diatom record shows that the marine parts of the sequence are dominated by high 13c and variable c n in the fresh water sequences the organic material is a mixture of both freshwater aquatic and terrestrial plant input that have relatively low 13c and high c n the application of 13c and c n ratios in the studied basin in general follow the environmental change recorded by the diatoms and shows the potential of bulk organic matter in the investigation of salinity change in isolation basins copyright 2005 john wiley sons ltd

onset of recent rapid sea level rise in the western atlantic ocean a high resolution record of sea level change spanning the past 1000 years is derived from foraminiferal and chronological analyses of a 2 m thick salt marsh peat sequence at chezzetcook nova scotia canada former mean tide level positions are reconstructed with a precision of 0 055 m using a transfer function derived from distributions of modern salt marsh foraminifera our age model for the core section older than 300 years is based on 19 ams 14c ages and takes into account the individual probability distributions of calibrated radiocarbon ages the past 300 years is dated by pollen and the isotopes 206pb 207pb 210pb 137cs and 241am between ad 1000 and ad 1800 relative sea level rose at a mean rate of 17 cm per century apparent pre industrial rises of sea level dated at ad 1500 1550 and ad 1700 1800 cannot be clearly distinguished when radiocarbon age errors are taken into account furthermore they may be an artefact of fluctuations in atmospheric 14c production in the 19th century sea level rose at a mean rate of 1 6 mm yr between ad 1900 and ad 1920 sea level rise accelerated to the modern mean rate of 3 2 mm yr this acceleration corresponds in time with global temperature rise and may therefore be associated with recent global warming 2005 elsevier ltd all rights reserved

petrology chronology and sequence of vein systems systematic magmatic and hydrothermal history of a major intracontinental shear zone canadian appalachians abstract intra continental shear zones developed during continental collision may experience prolonged magmatism and mineralization the cobequid shear zone formed part of a ne sw trending orogen parallel shear system in the late devonian early carboniferous where syn tectonic granite gabbro plutons and volcanic rocks 4 km thick were progressively deformed in late carboniferous to permian alleghanian collision of africa with laurentia formed the e w trending minas fault zone reactivating parts of the cobequid shear zone the 50 ma history of hydrothermal mineralization following pluton emplacement is difficult to resolve from field relationships of veins but sem study of thin sections provides clear detail on the sequence of mineralization the general paragenesis is albite quartz chlorite monazite biotite calcite allanite pyrite fe carbonates fe oxides minor sulfides calcite and synchysite chronology was determined from literature reports and new u pb la icpms dating of monazite and allanite in veins vein mineralization was closely linked to magmatic events vein emplacement occurred preferentially during fault movement recognised from basin margin inversion as a result of fractures opening in the damage zone of master faults the sequence of mineralization from ca 355 ma riebeckite and albite veins to ca 327 305 ma siderite magnetite and sulfide mineralization resembles precambrian iron oxide copper gold iocg systems in the literature the abundant magmatic na halogens and co2 in veins and some magmatic bodies characteristic of iocg systems were derived from the deeply subducted rheic ocean slab with little terrigenous sediment regional extension of the magdalen basin caused asthenospheric upwelling and melting of the previously metasomatized sub continental lithospheric mantle crustal scale strike slip faulting facilitated the rise of magmas resulting in high heat flow driving an active hydrothermal system

seismic coastal uplift in a region of subsidence holocene raised shorelines of samos island aegean sea greece abstract at least three raised shorelines micro benches and notches spanning a distance of more than 10 km and marked by a well preserved marine fauna have been identified along the nw coast of samos island aegean sea and area hitherto assumed to be characterised by a holocene marine transgression these fossil shorelines are nearly horizontal approximately 0 6 1 1 and 2 3 m above sea level and can be assigned to hitherto unnoticed earthquakes which occurred approximately 500 3600 3900 and possibly 1500 years ago some evidence of quaternary and longer term uplift has been found as well the observed uplift may be related to a zone of intense seismicity and faulting following the great meander buyuk menderes river graben in western anatolia but its structural explanation is not clear new evidence indicates that the geomorphological evolution of samos island and of the wider eastern aegean is not simply a result of marine transgression and of regional scale tectonics but also of earthquakes and that local scale tectonics are responsible for the evolution and present day morphology of at least a part of the coast of samos island as well as of other aegean coasts

the relationship between length and width of plutons within the crustal scale cobequid shear zone northern appalachians canada the lengths and widths have been measured for 69 component bodies of composite plutons along the cobequid shear zone plutons on major fault strands those with mylonite zones 0 1 km wide exhibit evidence of multiple intrusion of magma batches small plutons along short faults in stepover zones appear related to rapid emplacement of magma in bodies 1 5 4 km long by 0 1 2 km wide such small plutons show low enrichment in incompatible elements in older component bodies but increasing amounts in younger bodies as a result of progressive magma expulsion from crystal mush during crystallization and shear enhanced compaction in fault zones wider plutons generally occur along longer fault strands accommodating more strain and penetrating deeper into the crust and show enrichment in incompatible elements the width of the mylonitic fault zone is about 15 of the width of these plutons the length to width ratio of component bodies and composite plutons varies between 2 and 11 the best fit line describing these data has a slope of 1 056 which implies scaling behavior between plutonism and tectonic processes scalar properties of plutonic bodies are similar to those of faults but scalar relationships observed in component bodies do not apply to composite plutons

mode of emplacement of the slaufrudalur pluton southeast iceland inferred from three dimensional gps mapping and model building abstract the slaufrudalur pluton is a granitic pluton in the tertiary lava pile of southeast iceland excellent exposures of its roof and walls made it possible to map the shape of the pluton with high resolution gps based on the gps mapping and field observations we reconstructed the three dimensional shape of the slaufrudalur pluton with the aim to test which implications on the mechanisms of emplacement can be derived from this approach the reconstructed pluton shape is characterised by steep walls and a flat roof at map scale this shape and the internal compositional layering indicate that the pluton was probably emplaced by cauldron subsidence along subvertical faults that are parallel with the strike of the regional fissure swarms at the roof contact the pluton exploited the original layering of the flood basalts at outcrop scale however the roof was modified by magmatic stoping which resulted in a step like pattern on a scale that cannot be resolved in the three dimensional model hence the reconstruction of the three dimensional shape of the slaufrudalur pluton combined with structural field studies provided valuable information about the mechanism of its emplacement on pluton scale for a comprehensive understanding of all mechanisms involved in the emplacement of the slaufrudalur pluton detailed structural field studies remain essential

early carboniferous deformation and mineralization in the cobequid shear zone nova scotia an 40ar 39ar geochronology study latest devonian to early carboniferous igneous rocks along the cobequid shear zone of central nova scotia record a complex history of intrusion volcanism deformation and hydrothermal alteration twenty new 40ar 39ar age determinations have been made on biotite and hornblende separates from rocks that constrain these events the mafic plutons of the cobequid shear zone are synchronous with the previously dated granitoid plutons 363 355 4 ma with the exception of the younger folly lake gabbro 355 350 4 ma high temperature shear deformation continued along the cobequid shear zone during this entire period of pluton emplacement several samples from mylonitic and hydrothermally altered rocks with dates ca 340 ma indicate renewed movement along the cobequid shear zone at this time accompanied by minor magmatism younger 330 320 ma ages reflect final movement along the rockland brook fault resulting in mid namurian uplift of the cobequid highlands following this regional alleghenian event ther

evolution of late palaeozoic shearing in the cobequid highlands constraints on the fragmentation of the appalachian orogen in nova scotia along intra continental shear zones

dating transcurrent terrane accretion an example from the meguma and avalon composite terranes in the northern appalachians the polygenetic minas geofracture separates the meguma and avalon composite terranes of the maritime appalachians dynamically recrystallized muscovite and biotite occur within d3 shear zones which developed during dextral movement along the geofracture these record 40ar 39ar plateau ages between circa 360 and 370 ma comparable plateau ages are recorded by micas within undeformed portions of granitic plutons and their low pressure contact metamorphic aureoles these are similar to u pb ages previously reported for igneous monazite therefore indicating relatively rapid postmagmatic cooling at shallow crustal levels the d3 fabrics were superimposed on earlier s1 structures which formed during initial amalgamation of the meguma and avalon composite terranes whole rock slate phyllite samples collected outside high temperature portions of the plutonic contact aureoles yield 40ar 39ar plateau ages which correspond to groupings of circa 400 395 ma 390 385 ma and 380 375 ma these are interpreted to date diachronous formation of the s1 fabrics and concomitant low grade regional metamorphism in the circa 25 ma between initial amalgamation and granitic plutonism it is inferred that there was a slow rise of isotherms through the crust as a result of overthrust tectonic thickening this led to crustal melting and the production of widespread granitic magmas which were emplaced immediately prior to d3 dextral shearing

sedimentary response of pagham harbour southern england to barrier breaching in ad 1910 this paper examines the evolution of pagham harbour southern england following storm induced breaching of a protective barrier in ad 1910 stratigraphic studies of sediments collected from intertidal areas show the presence of a distinct stratigraphic horizon in the northeast of pagham harbour at ca 0 to 1 0 m ordnance datum od radiometric data indicate that this horizon is a reclamation surface formed after land claim in ad 1846 following marine flooding in ad 1910 sediment has accreted relatively rapidly at a broadly constant rate of between 4 and 8 mm a 1 wave and or tidal energy have decreased and extensive marshes have developed an asymptotic reduction in sediment accretion rate through time as predicted in various theoretical models of salt marsh accretion is not observed over the entire pagham harbour area the period between ad 1948 and ad 1986 has seen an average marsh loss of 0 0087 km2 a 1 which is relatively small in comparison with other more exposed sites in the local area historically breached sites such as pagham harbour are common around european coasts and these provide important natural laboratories within which the medium term decadal to centennial coastal response to barrier breaching and to managed realignment coastal protection schemes can be assessed

late devonian carboniferous detachment faulting and extensional tectonics in western cape breton island nova scotia canada abstract shallow dipping detachment faults have played a key role in the evolution of the late devonian to carboniferous maritimes basin of western cape breton island the faults are responsible for large scale post orogenic crustal thinning and denudation of mid crustal levels tournaisian and westphalian clastic sedimentation can be related to detachment faulting along the margaree shear zone msz and the ainslie detachment ad respectively the msz consists of thick shallow dipping retrogressive mylonite overprinted by cataclastic horizons brittle detachment faults and chloritic breccia the shear zone crosscuts and transports low grade late devonian bimodal volcanic rocks and redbeds of the fisset brook formation in its hanging wall towards the west and juxtaposes them against exhumed medium to high grade metamorphic rocks and basement in its footwall locally the mylonite is 200 700 m thick and outcrops along strike from north to south for approximately 60 km tournaisian coarse clastic units and debris flow deposits of the horton group unconformably overlie ductile mylonite of the msz due to incision of brittle faults into the msz regional transgression and marine flooding of the extensional complex and exhumed units are marked by the thick visean carbonate and evaporite deposits of the windsor group the carbonates reflect a relatively quiescent tectonic regime and widespread subsidence was likely due to the cessation of extension related thermally induced buoyancy in a tectonically thinned crust the ainslie detachment nucleated as a regional flat lying fault along the carbonate evaporite contact at the top of the macumber formation forming calc mylonite near the base of the windsor group significant stratigraphic omissions in the windsor group above the detachment provide clear evidence of an extensional regime during faulting clastic deposits of the westphalian cumberland group are bounded by the detachment and sedimentation is related to listric normal faults which cut down section towards the west southwest the documentation of detachment faults has widespread implications for the interpretation of the post orogenic evolution of the northern appalachians an extensional regime can now be recognized deep reflection seismic data are interpreted in light of the new findings and can be related to late devonian carboniferous basin formation

strain partitioning in transpression zones abstract transprcssional strain acting upon structurally anisotropic rocks can be partitioned into separate deformational domains of pure shear and simple shear this contrasts with homogeneous transpression in which both the pure shear and the simple shear strain components are uniformly distributed across the zone of deformation structural weaknesses capable of partially or fully accommodating one component of deformation include lithological contacts rheological heterogeneities and faults or shear zones situated within the deformation zone or lying along its boundaries partitioning of transprcssional strain can occur when stress is applied oblique to pre existing structural weaknesses or can occur during later stages of progressive strain when the early deformation of isotropic rocks imparts sufficient anisotropy to allow subsequent strain to be partitioned partitioning of transpressional strain into domains lying parallel to the deformation zone boundaries can be distinguished from fault stepped transpression in which strain is partitioned along the length of a segmented fault zone mesofracture analysis of rocks affected by mid devonian deformation on both sides of the highland boundary fault zone hbfz in central scotland shows that strain was not homogeneous the mesofracture data suggest that regional north south compression orientated oblique to the pre existing ne sw trending hbfz was partitioned into separate deformational domains the hbfz accommodated most of the simple shear component whilst the rocks flanking the zone were deformed predominantly by pure shear a contemporary example is the san andreas fault in central california where analyses of neo tectonic stresses show that the direction of principal compression is perpendicular to the fault zone many examples of the partitioning of transpressional strain have also been recognised at destructive plate margins where the direction of plate motion is oblique to the edge of the over riding plate

a re analysis of the late bronze age eruption and tsunami of santorini greece and the implications for the volcano tsunami hazard the paroxysmal eruption of santorini ca 3500 bp referred to as the late bronze age lba eruption probably generated multiple tsunami their occurrence and impacts being cited frequently in scientific papers and articles this paper examines what is known about any lba tsunami noting possible mechanisms of generation and identifying sedimentological traces firstly the eruption sequence is outlined providing the context in which tsunami genesis may have occurred secondly the arguments forwarded for the tsunami and a summary of the evidence is given thirdly results of a new geological investigation for lba tsunami deposits at 41 coastal sites from crete and kos are presented the data are used to test the hypothesis that the lba eruption generated an east mediterranean wide tsunami it will be seen that no terrestrial geological evidence is identified the paper re examines the original arguments presented for lba tsunami challenging them because their founding assumptions are flawed together the new data and the re analysis of the original tsunami hypothesis indicate that there is insufficient evidence to demonstrate that any significant far field tsunami propagated throughout the entire east mediterranean as frequently purported some terrestrial evidence exists to suggest localised near field tsunami inundation there is good submarine evidence however to suggest that a tsunami was focused to the w and wsw the results have important implications for understanding the volcano related tsunami hazard within the region and elsewhere

chronology of devonian to early carboniferous rifting and igneous activity in southern magdalen basin based on u pb zircon dating fifteen u pb zircon radiometric age determinations have been made on igneous rocks of middle devonian to early carboniferous age from the southern margin of the magdalen basin in cape breton island and northern mainland nova scotia volcanic rocks interbed with early rift basin sedimentary rocks with some palynological biostratigraphy dated intrusive rocks cut these sedimentary units our biostratigraphically constrained ages are in close agreement with the current devonian time scale combined with previously published data the age determinations show that igneous activity occurred in four pulses middle devonian 390 385 ma early late devonian 375 370 ma latest devonian to early tournaisian 365 354 ma and late tournaisian to early visean ca 339 ma middle devonian 385 389 ma volcanic rocks are confined to the guysborough group the fisset brook formation basalt and minor rhyolite in the type area and elsewhere in cape breton island and northern mainland nova scotia is late devonian c

climatology and variability of historical soviet snow depth data some new perspectives in snow indian monsoon teleconnections this study presents the monthly climatology and variability of the historical soviet snow depth data this data set was developed under the bilateral data exchange agreement between united states of america and the former union of soviet socialist republics the original data is for 284 stations for periods varying from 1881 upto 1985 the seasonal cycle of the mean snow depth has been presented both as spatial maps and as averages over key locations the deepest snow 80 cms day areas are found over siberia in particular over 80 100 e 55 70 n during march over the course of the annual cycle average snow depth over this region changes dramatically from about 10 cms in october to about 80 cms in march the variability is presented in the form of spatial maps of standard deviation to investigate the interaction of snow depth with indian monsoon rainfall imr lag and lead correlation coefficients are computed results reveal that the winter time snow depth over western eurasia surrounding moscow eastern eurasia in central siberia shows significant negative positive relationship with subsequent imr following the monsoon the signs of relationship reverse over both the regions this correlation structure is indicative of a midlatitude longwave pattern with an anomalous ridge trough over asia during the winter prior to a strong weak monsoon as the time progresses from winter to spring the coherent areas of significant relationship show southeastward propagation empirical orthogonal function analysis of the snow depth reveal that the first mode describes a dipole type structure with one centre around moscow and the other over central siberia depicting similar pattern as the spatial correlation structure the decadal scale imr variations seem to be more associated with the northern hemisphere midlatitude snow depth variations rather than with the tropical enso el nino southern oscillation variability

stratigraphic significance of upper devonian and lower carboniferous miospores from the type area of the horton group nova scotia late devonian late famennian miospores have been found in the lowermost 7 3 m of the horton group on harding brook in the type area windsor subbasin nova scotia below tournaisian miospores of the emphanisporites rotatus indotriradites explanatus zone extending the age of the horton group in the type area down into the latest devonian shows that the lowest beds of the 1000 m thick group are coeval with latest devonian rocks elsewhere in the maritimes basin that have been excluded from the horton group by some authors evidence presented here favours the argument that late devonian rocks lithologically similar to the horton group deposited on the acadian unconformity should be included in that group miospore evidence indicates a minimum age of about 355 ma for exhumation of the northeastern part of the south mountain batholith

pluton emplacement by wall rock thrusting hanging wall translation and extensional collapse latest devonian plutons of the cobequid fault zone nova scotia canada

relation between eurasian snow cover snow depth and the indian summer monsoon an observational study abstract satellite derived snow cover data for 22 yr and snow depth data for 9 yr over eurasia have been analyzed to reexamine the possible relation of snow with the indian summer monsoon in contrast to the previous studies that use snow cover averaged over all of eurasia as a single number the frequency of occurrence of snow at each grid point over eurasia is correlated with the indian summer monsoon rainfall thus specific geographical regions over eurasia that are responsible for the well known inverse relationship between eurasian snow cover and indian monsoon rainfall are delineated it is found somewhat surprisingly that western eurasia is the only geographical region for which a significant inverse correlation exists between winter snow cover and subsequent summer monsoon rainfall however composites for high and low snow cover over eurasia show spatially homogeneous large scale patterns of snow cover and surface temperature anomalies winters of high and low snow cover for eurasia are found t

decadal change of the spring snow depth over the tibetan plateau the associated circulation and influence on the east asian summer monsoon abstract the decadal change in the spring snow depth over the tibetan plateau and impact on the east asian summer monsoon are investigated using station observations of snow depth data and the ncep ncar reanalysis for 1962 93 during spring march april both the domain averaged snow depth index sdi and the first principal component of the empirical orthogonal function eof analysis exhibit a sharp increase in snow depth after the late 1970s which is accompanied by excessive precipitation and land surface cooling the correlation between sdi and precipitation shows a coherent remote teleconnection from the tibetan plateau northern india to western asia it is found that the increased snow depth over the plateau after the mid 1970s is concurrent with a deeper india burma trough an intensified subtropical westerly jet as well as enhanced ascending motion over the tibetan plateau additional factors for the excessive snowfall include more moisture supply associated with the intensification of the south

sediment accretion and recent sea level rise in the solent southern england inferences from radiometric and geochemical studies abstract a detailed radionuclide and geochemical study has been carried out on recent sediments from the solent estuarine system southern england the vertical distributions of a series of radionuclides 210 pb 137 cs 238 pu 239 240 pu 241 am and 60 co have been examined which provide a measure of the rate of sediment accumulation in southern england estuaries the reliable use of radionuclides as indicators of sediment accumulation depends in part on their chemical immobility lack of redox migration 60 co in particular shows evidence for redox mobilization hence it is essential to use a number of chemically different or inert radionuclides to eliminate possible bias in calculated sediment accumulation rates while local intra estuary effects influence rates of sediment accumulation the main control of vertical saltmarsh growth over the solent area is a rise in mean sea level dating of saltmarsh cores indicates a 4 5 mm year 1 rise in relative sea level over the last 100 years in good agreement with tide gauge data comparison with data from the literature implies that a recent acceleration in sea level rise has occurred from 1 2 mmyear 1 to 4 5 5 mm year 1 possibly due to changes in tidal regime or an acceleration in crustal subsidence

coastal wetlands as recorders of earthquake subsidence in the aegean a case study of the 1894 gulf of atalantiearthquakes central greece abstract earthquakes may have a major impact on the morphology and evolution of coasts in tectonically active areas in the area of the gulf of atalanti central greece a damaging earthquake sequence in 1894 is reported to have caused nearshore slumping tsunami induced flooding and decimetre to metre scale coastal subsidence the earthquakes caused major changes to coastal configuration in particular the separation of the gaiduronisi peninsula from the mainland detailed stratigraphical microfossil and radiometric 210pb and 137cs analyses of coastal wetlands around the gulf of atalanti show that these environments preserve evidence of sudden lasting subsidence contemporaneous with the 1894 events with foraminiferal assemblages at a site on the mainland opposite the island indicating an abrupt change from supratidal soil to intertidal marine conditions the elevation change indicated by this terrestrial to marine transition is 30 80 cm the coastal stratigraphy in the atalanti area however lacks laterally extensive sharp soil mud contacts or tsunami deposits of the type used in identifying past earthquake subsidence events at plate boundary settings despite the major earthquake induced changes in coastal configuration the stratigraphical signature of the 1894 earthquakes is relatively subtle and is consequently difficult to distinguish from other rapid coastal changes e g storm events or barrier breaching without high resolution dating control and reference to documentary records for this reason coastal wetland stratigraphies are only likely to be useful in identifying pre historical or poorly documented earthquakes in the aegean at sites where metre scale coseismic elevation changes and or major tsunami inundation have occurred in addition the resolution of the biostratigraphic data reported here is insufficient to distinguish between the contrasting fault rupture models for the 1894 events the coastal elevation changes recorded in these wetlands however are best accounted for by a slip of 1 m on a multi segment fault

persistent mafic igneous activity in an a type granite pluton cobequid highlands nova scotia the west moose river pluton is one of a series of latest devonian early carboniferous plutons of granite and gabbro diorite in the cobequid highlands southern edge of avalon zone intrusion of minor gabbro preceded emplacement of the granite which is fractured and cut by later mafic dykes of which some predate and others postdate a namurian compressive deformation minor hybrid phases reflect mixing of mafic and felsic magmas which are also represented by basalt and rhyolite in the synchronous fountain lake group the mafic rocks are continental tholeiites reflecting regional early carboniferous extension later dykes are more fractionated with high p2o5 tio2 and other high field strength elements the dykes are pervasively altered probably by residual fluids from the granite hydrothermally circulated by the hot mafic rocks higher ga al hf and zn content in basalts than dykes suggests upward increase in halogen complexing in the mafic plumbing system late stage fluids concentrated k rb an

role of the tibetan plateau thermal forcing in the summer climate patterns over subtropical asia the mechanism of the tibetan plateau tp thermal forcing in influencing the summer climate patterns over subtropical asia is investigated by means of ncep ncar reanalysis diagnosis results show that since the tp is a huge elevated heating source with the strongest heating in the surface layers in summer the thermal adaptation results in a shallow cyclonic circulation near the surface and a deep anticyclonic circulation above it according to the steady barotropic vorticity equation for large scales airflow must converge in the lower layers and diverge in the higher layers over the eastern side of the tp however the western side of the tp is characterized by a reversed structure i e divergence in lower layers but convergence in higher layers hence pumping and sucking processes bring in upward and downward movement over the east and west sides of the tp respectively such a circulation is embedded in the large scale circulation that is forced by the eurasian continental heating because the tp together with iran plateau are located at the central and eastern parts of the continent and because the orography induced circulation is in phase with the continental scale circulation the role of the tp thermal forcing is to intensify the east asian monsoon to its east and the dry and hot desert climate in mid asia to its west the summertime thermal forcing of the rockies and andes can generate similar circulations along the two subtopics as the tp does since they are located near the western coasts but the lower troposphere poleward flow that is induced by orographic thermal forcing does not coincide with the poleward flows over the eastern coastal region that is induced by continental heating and the monsoon rainfall in north and south america is not as strong as in east asia however the equatorward flow and the associated subsidence induced by the two mountain ranges along the western coasts of both north and south america are in phase with those induced by continental heating these contribute to the formation of the stable low stratus clouds and strong long wave radiative cooling over the eastern subtropical pacific regions just off the western coast of the continent

on granitoid emplacement and related structures a review granitoid magmas are emplaced at the upper crust under a complex interaction of gravitational processes and horizontal tectonics natural intrusive bodies show a wide variety of structural patterns that must be strongly related with their dynamic history of ascent and emplacement comparisons of natural structural patterns with experimental and numerical models are necessary to interpret in a coherent fashion the emplacement mechanism involved from natural experimental numerical and theoretical considerations one can reach important conclusions on the problem of ascent and final emplacement of granitoid magmas in the earth s crust the present paper reviews the principal emplacement mechanisms referred to in the literature that is doming diapirism ballooning stoping cauldron subsidence and dike propagation dike propagation is the most effektive process in magma transport from deep zones in the crust and upper mantle extensional fractures for dike propagation and magma ascent can be developed at depth in the crust according to the modern dike propagation theory in orogenic domains magmas reach the upper crust through narrow channels or dikes and are accumulated in a final reservoir in the form of a discordant supracrustal pluton or a ballooning pluton if during emplacement any regional deformation acts simultaneously

response of the indian summer monsoon circulation and rainfall to seasonal snow depth anomaly over eurasia several observational and modeling studies indicate that the indian summer monsoon rainfall ismr is inversely related to the eurasian snow extent and depth the other two important surface boundary conditions which influence the ismr are the pacific sea surface temperature sst to a large extent and the indian ocean sst to some extent in the present study observed soviet snow depth data and indian rainfall data for the period 1951 1994 have been statistically analyzed and results show that 57 of heavy snow events and 24 of light snow events over west eurasia are followed by deficient and excess ismr respectively out of all the extreme monsoon years care has been taken to identify those when eurasian snow was the most dominant surface forcing to influence ismr during the years of high low eurasian snow amounts in spring winter followed by deficient excess ismr atmospheric fields such as temperature wind geopotential height velocity potential and stream function based on ncep ncar reanalyses have been examined in detail to study the influence of eurasian snow on the midlatitude circulation regime and hence on the monsoon circulation results show that because of the west eurasian snow anomalies the midlatitude circulations in winter through spring show significant changes in the upper and lower level wind geopotential height velocity potential and stream function fields such changes in the large scale circulation pattern may be interpreted as precursors to weak strong monsoon circulation and deficient excess ismr the upper level velocity potential difference fields between the high and low snow years indicate that with the advent of spring the winter anomalous convergence over the indian region gradually becomes weaker and gives way to anomalous divergence that persists through the summer monsoon season also the upper level anomalous divergence centre shifts from over the northern hemisphere and equator to the southern hemisphere over the indian ocean and australia

observed relationship of spring and summer east asian rainfall with winter and spring eurasian snow abstract this study investigates the relationship between spring and summer rainfall in east asia and the preceding winter and spring snow cover depth over eurasia using station rainfall observations satellite observed snow cover satellite derived snow water equivalent and station observations of the number of days of snow cover and snow depth correlation analysis shows that snow depth anomalies can persist from winter to spring whereas snow cover anomalies cannot in most regions of eurasia locally snow cover and snow depth anomalies in february are not related in most regions to the north of 50 n but those anomalies in april display consistent year to year variations the results suggest that the winter snow cover cannot properly represent all the effects of snow and it is necessary to separate the winter and spring snow cover in addressing the snow monsoon relationship spring snow cover in western siberia is positively correlated with spring rainfall in southern china the circulation anomalies

the role of dextral transpressional faulting in the evolution of an early carboniferous mafic felsic plutonic and volcanic complex cobequid highlands nova scotia canada abstract the wentworth plutonic complex consisting of gabbro and granite was emplaced in the earliest carboniferous in the cobequid shear zone of the northern appalachians the plutonic complex is coeval with a 5 km thick pile of volcanic rocks early alkalic a type granite correlates with thick felsic pyroclastics and minor basalt which are overlain by 1 5 km thick basalts that correlate with a large gabbro pluton that is intruded in turn by late granites the basalt and gabbro are fe rich tholeiites the geochemistry of the late granites suggests that they formed by differentiation of a granodioritic magma resulting from assimilation of early granite by the gabbroic magma the wentworth plutonic complex lies on the north side of the dextral rockland brook fault near the western tip of wedge shaped basement block of the avalon terrane field observations of mesoscopic structures and map contacts show that the plutonic bodies at all structural levels are related to transpressive strike slip faults dykes parallel to the mylonitic foliation in the rockland brook fault zone and at the contacts between igneous phases suggest that the plutons developed largely through dyke to pluton construction the plutonism was initiated by dyking related to major faults under transpression that was partitioned into shear zone bounded blocks while the sinking of those blocks finally provided the space for mafic magma emplacement dyking was active over at least a 10 ma time period the overall location of plutonism in the cobequid shear zone appears related to its position at the intersection of the shear zone bounding the southwestern margin of the magdalen basin and the e w transpressional contact of the avalon and meguma terranes magmatism enabled thermomechanical softening of the crust and the vertical and lateral extrusion of the wedge shaped basement blocks whose movement controlled the localisation of the voluminous magmatic activity

using idealized snow forcing to test teleconnections with the indian summer monsoon in the hadley centre gcm anomalous heavy snow during winter or spring has long been regarded as a possible precursor of deficient indian monsoon rainfall during the subsequent summer however previous work in this field is inconclusive in terms of the mechanism that communicates snow anomalies to the monsoon summer and even the region from which snow has the most impact in this study we explore these issues in coupled and atmosphere only versions of the hadley centre model a 1050 year control integration of the hadcm3 coupled model which well represents the seasonal cycle of snow cover over the eurasian continent is analysed and shows evidence for weakened monsoons being preceded by strong snow forcing in the absence of enso over either the himalaya tibetan plateau or north west eurasia regions however empirical orthogonal function eof analysis of springtime interannual variability in snow depth shows the leading mode to have opposite signs between these two regions suggesting that competing mechanisms may be possible to determine the dominant region ensemble integrations are carried out using hadam3 the atmospheric component of hadcm3 and a variety of anomalous snow forcing initial conditions obtained from the control integration of the coupled model forcings are applied during spring in separate experiments over the himalaya tibetan plateau and north west eurasia regions in conjunction with climatological ssts in order to avoid the direct effects of enso with the aid of idealized forcing conditions in sensitivity tests we demonstrate that forcing from the himalaya region is dominant in this model via a blanford type mechanism involving reduced surface sensible heat and longwave fluxes reduced heating of the troposphere over the tibetan plateau and consequently a reduced meridional tropospheric temperature gradient which weakens the monsoon during early summer snow albedo is shown to be key to the mechanism explaining around 50 of the perturbation in sensible heating over the tibetan plateau and accounting for the majority of cooling through the troposphere

the mortagne granite pluton france emplaced by pull apart along a shear zone structural and gravimetric arguments and regional implication the emplacement mechanism and kinematics and the 3 d geometry of the variscan granite pluton of mortagne are interpreted using systematic measurements of the granite structure allied with micro structural observations from a detailed gravimetric study it is proposed that magma infilled a pull apart structure which formed along a jog of a northwest southeast trending sinistral zone of shear a second episode of shearing under a dextral regime and independent of emplacement was responsible for perigranitic tectonites these successive transcurrent opposite movements already documented for variscan times in western france are discussed concerning the age of the mortagne pluton 313 15 m y

emplacement of the miocene west naxos pluton aegean sea greece a structural study synmagmatic and solid state structures within the naxos pluton and its rim may provide insight into the interplay between plutonism and regional deformation at upper crustal level within the hornblende biotite granite of western naxos synmagmatic foliations display two distinct patterns onion skin in the north and tangential to the rim in the south the two areas are separated by the ne trending glinadon fault deformed mafic enclaves in the pluton are prolate with their long axes parallel to the synmagmatic lineation in contrast phenocryst distribution analysis using the fry method defines an apparent oblate strain with a horizontal stretching lineation planar markers within the pluton progressively steepen through the vertical at the east pluton border several lines of evidence such as dykes intruding axial areas of rim parallel folds foliated or folded aplite veins folds and spaced cleavage in the mollase and inverted stratigraphy suggest pluton emplacement and deformation during transpressional deformation a northward divergent flow regime with magma spreading out mainly from the naxos fault and the deflection of both the synmagmatic foliation pattern and the flow lines at the glinadon fault suggest that the ne sw and n s trending faults were active during pluton formation in the south the pluton has grown by the expansion of dykes occupying p shear positions with respect with the naxos fault in the north a piecemeal block down drop complements this process and favours voluminous magma concentration during the late evolutionary stages of pluton construction the magma chamber was compartmentalized into ne trending sectors affected by block rotation in an anticlockwise manner understanding the role of faults in the emplacement of the naxos pluton is important for understanding emplacement of other plutons in the aegean sea region since most of them are controlled by n s ikaria pluton or ne tinos serifos and delos plutons trending faults

reconstructing historical trends in metal input in heavily disturbed contaminated estuaries studies from bilbao southampton water and sicily estuaries may be important reservoirs for contaminants as they tend to act as sinks for fine contaminant reactive sediments and historically they have acted as centres for industrial and urban development analysis of dated sediment cores from these areas may allow historical trends in heavy metal input to be reconstructed and recent and historical inputs of metal contaminants to be compared undisturbed saltmarsh settings have been used widely in the reconstruction of historical trends in metal input as saltmarshes provide a stable vegetated substrate of dominantly fine sediments and are less prone to erosion and reworking than adjacent mudflat areas in comparison much less research on historical pollution trends has been undertaken at estuarine sites which are prone to severe local disturbance such as intertidal areas which are routinely dredged or where sedimentary processes have been modified by human activities such as shipping salt working port activities land claim etc this paper assesses the usefulness of 210pb and 137cs dating combined with geochemical studies in reconstructing historical trends in heavy metal input and sediment accretion in 3 heavily modified industrialised estuarine areas in europe the bilbao estuary spain southampton water uk and the mulinello estuary sicily of these sites only a salt marsh core from the mulinello estuary provides a high resolution record of recent heavy metal inputs in southampton water only a partial record of changing metal inputs over time is retained due to land claim and possible early diagenetic remobilisation while at bilbao the vertical distribution of heavy metals in intertidal flats is mainly controlled by input on reworked sediment particles and variations in sediment composition where 137cs and 210pb distributions with depth allow a chronology of sediment deposition to be established and early diagenetic remobilisation has been minimal mudflat and saltmarsh cores from even the most heavily disturbed estuarine sites can provide useful information on variations in historical contaminant input when the sediments have been vigorously mixed or reworked large scale compositional variations are present or significant early diagenetic remobilisation has occurred however only general information on the scale of contamination can be obtained

the alleghanian southern appalachian piedmont a transpressional model alleghanian dextral transpression produced multiple strike slip shear zones forming a contractional mega duplex in the central and southern appalachian piedmont structural upwelling along the zones is identifiable as crustal arching on seismic reflection profiles that roughly corresponds to the piedmont gravity high the structural upwelling coincides both temporally and spatially with areas of peak alleghanian plutonism and metamorphism the compositionally bimodal plutons generally occur in or around the fault zones and are isotopically primitive geobarometry of cognate xenocryst inclusions of coexisting plagioclase and pyroxene from a granitoid indicates 8 11 kbar or 31 to 42 5 km depth to proposed source region this depth roughly corresponds to the pre erosional location of multiple reflections beneath the arches on seismic profiles that are interpreted as the moho the granitoids are proposed to have formed by partial melting of the lowermost crust through heat from mafic intrusions and decompression resulting from crustal arching beneath the strike slip faults the granitoids ascended along the strike slip faults and were emplaced in or near them the crustal arching and melting processes appear to be important mechanisms in the development of strike slip orogens

extensional pluton emplacement models do they work for large plutonic complexes shallow crustal to mid crustal magma emplacement models commonly rely on local or regional extension to solve the room problem we argue that existing extensional models explain the emplacement of sheeted dike complexes or internally layered plutons but are not as easily reconciled with the emplacement of elliptically shaped plutons or batholiths for the following reasons 1 rock strengths and crustal stresses prevent large voids from existing at depth and therefore require wall rock extension to be balanced by magma influx 2 rates of extension are controlled by fault slip rates of millimetres to centimetres per year and thus require numerous small injections of magma and 3 because of their sheetlike shapes and small thicknesses these small magma injections will cool rapidly and form sheeted plutons or dike swarms extension may however facilitate emplacement of elliptically shaped plutons in concert with other mechanisms if certain kinematic constraints are satisfied

the effect of enso on tibetan plateau snow depth a stationary wave teleconnection mechanism and implications for the south asian monsoons abstract an atmospheric stationary wave teleconnection mechanism is proposed to explain how enso may affect the tibetan plateau snow depth and thereby the south asian monsoons using statistical analysis the short available record of satellite estimates of snow depth and ray tracing it is shown that wintertime enso conditions in the central pacific may produce stationary barotropic rossby waves in the troposphere with a northeastward group velocity these waves reflect off the north american jet turning equatorward and enter the north african asian jet over the eastern atlantic ocean once there the waves move with the jet across north africa south asia the himalayas and china anomalous increases in upper tropospheric potential vorticity and increased wintertime snowfall over the tibetan plateau are speculated to be associated with these rossby waves the increased snowfall produces a larger tibetan plateau snowpack which persists through the spring and summer and weakens the intensity of the

iod influence on the early winter tibetan plateau snow cover diagnostic analyses and an agcm simulation using diagnostic analyses and an agcm simulation the detailed mechanism of indian ocean dipole iod influence on the early winter tibetan plateau snow cover ewtpsc is clarified in early winter of pure positive iod years with no co occurrence of el nino the anomalous dipole diabatic heating over the tropical indian ocean excites the baroclinic response in the tropics since both baroclinic and barotropic components of the basic zonal wind over the arabian peninsula increase dramatically in early winter due to the equatorward retreat of the westerly jet the baroclinic mode excites the barotropic rossby wave that propagates northeastward and induces a barotropic cyclonic anomaly north of india this enables the moisture transport cyclonically from the northern indian ocean toward the tibetan plateau the convergence of moisture over the plateau explains the positive influence of iod on the ewtpsc in contrast the basic zonal wind over the arabian peninsula is weak in autumn this is not favorable for excitation of the barotropic rossby wave and teleconnection even though the iod related diabatic heating anomaly in autumn similar to that in early winter exists this result explains the insignificant significant positive partial correlation between iod and the autumn early winter tibetan plateau snow cover after excluding the influence of enso the sensitivity experiment forced by the iod related sst anomaly within the tropical indian ocean well reproduces the baroclinic response in the tropics the teleconnection from the arabian peninsula and the increased moisture supply to the tibetan plateau also the seasonality of the atmospheric response to the iod is simulated

estimation of paleostress orientation within deformation zones between two mobile plates the orientation of the principal stress axes within deformation zones between two mobile plates is modeled here analytically using a thin plate theory the simple analytical approach helps to explain why plates cease to move after collision orogenic periods last only several tens of million years because the stress associated with a particular constant driving force causing a constant strain rate is no longer able to maintain a significant horizontal displacement in contrast the uplift rate increases rapidly as the horizontal velocity decreases and this may explain why the termination of orogenic epochs are usually heralded by the rapid deposition of thick sequences of immature sedimentary rocks or flysch the analytical model also elaborates the relationship between homogeneous bulk deformations driven by a constant stress orientation and those due to a fixed displacement direction of physical boundaries of the deformation zone two major kinematic possibilities are considered 1 plates converging either orthogonally or obliquely making the deformation zone an analogue for orogenic collision and 2 plates diverging either orthogonally or obliquely so that the deformation zone is dynamically similar to initiating rift basins the theoretical investigation led to the formulation of the following rules deformation zones between converging plates have the major axis of bulk deviatoric stress coinciding with the bisector of the acute angle between the relative plate velocity vector and the normal to the deformation zone boundary in case of extension within a deformation or rift zone separating diverging plates the bisector will outline the minor axis of the bulk deviatoric stress the deformation tensor of the analytical model yields a new method for estimating the orientation of paleostress in natural examples here applied to the deformed wall rock of the moroccan border fault the marker used is a competent sequence of devonian sandstone and limestone asymmetrically folded adjacent to the dextral border fault the steeply plunging z folds of the marker beds suggest that the principal deviatoric paleostress 1 was oriented 37 44 to the fault trace the age of the moroccan border fault is poorly constrained and may be variscan or younger the 1 orientation implies a major component of simple shear parallel to the strike slip fault and a minor component of extension perpendicular to the fault trace the implied crustal movement is compatible with the modern tectonics of the eurasian african collision zone where part of the differential motion between the eurasian and african plates is accommodated by strike slip faults

discovery of minoan tsunami deposits the hellenic arc is a terrane of extensive quaternary volcanism one of the main centers of explosive eruptions is located on thera santorini and the eruption of the thera volcano in late minoan time 1600 1300 b c is considered to have been the most significant aegean explosive volcanism during the late holocene the last eruptive phase of thera resulted in an enormous submarine caldera which is believed to have produced tsunamis on a large scale evidence suggesting seawater inundation was found previously at some archaeological sites on the coast of crete however the cause of the tsunami and its effects on the area have not been well understood on the aegean sea coast of western turkey didim and fethye and crete gouves we have found traces of tsunami deposits related to the thera eruption the sedimentological consequences and the hydraulics of a thera caused tsunami indicate that the eruption of thera volcano was earlier than the previous estimates and the tsunami did not have disruptive influence on minoan civilization

sense of displacement on the cobequid chedabucto fault system nova scotia canada the cobequid chedabucto fault system of the canadian appalachians is a major anastomosing fault system over 300 km in length it separates the meguma terrane of southern nova scotia from the avalon terrane to the north these terranes are distinct tectonic and lithological entities in the appalachian orogen two areas at either end of this fault system have been examined in detail to determine the sense and history of offset along it both areas are situated on major component fault zones of the system and both exhibit structures due to early intense ductile shearing that are overprinted by semi brittle to brittle structures caused by later faulting along the eastern chedabucto fault zone area a ductile structures were examined this area is characterized by the progressive development of s c textures and shear bands rotated syntectonic porphyroblasts and asymmetric minor folds features indicative of and caused by ductile shearing along the western cobequid fault zone area b semi brittle and b

geochemical and stratigraphic indicators of late holocene coastal evolution in the gythio area southern peloponnese greece the study of past changes in sea level and of historical and pre historical coastal evolution using coastal sediment stratigraphies is well established over a range of geographic areas in both seismic and aseismic settings in the eastern mediterranean however such studies are less common and notably the use of sediment geochemistry and its combination with lithostratigraphic studies to analyze palaeoenvironmental and palaeo sea level change has not been explored to any significant extent despite the fact that geochemical data have been successfully used elsewhere to aid in the identification of sea level changes here we use a combined geochemical stratigraphic and microfossil approach to reconstruct late holocene coastal evolution and sea level change at two sites near gythio in the southern peloponnese greece the sites show stratigraphic and geochemical evidence of the presence in late helladic times ca 1500 bc of barrier protected coastal lagoonal wetland environments which have gradually infilled over the last ca 3500 yr archaeological remains and ceramic and charcoal bearing horizons within the sediment sequences indicate late roman occupation of the area although there is no sedimentary evidence of significant pre roman activity at the study sites an apparent brackish wetland peat deposit at 3 4 m overlain by anoxic lagoonal clays at kamares kato vathi bay shows a calibrated radiocarbon age of 1640 1440 bc suggesting a relative sea level rise of 0 8 1 mm yr in this area over the past 3500 yr in good agreement with previous archaeological and sea level modelling studies there is no evidence based on the stratigraphic microfossil or geochemical record of sudden marine flooding events related to local or regional seismic activity despite the presence of the area in a seismically active zone known to be subject to periodic earthquakes and tsunami the data highlight the utility of combining geochemical and stratigraphic studies in the reconstruction of coastal evolution and the study of palaeo sea level changes particularly in sequences such as those described here where microfossils are poorly preserved

fractured latest devonian granites of the west moose river pluton along the cobequid shear zone nova scotia implications for regional mineralization latest devonian 365 358 ma a type granites in the cobequid highlands host complex sequences of rare earth element ree and other hydrothermal minerals the west moose river pluton is the only pluton truncated and brittly deformed by the mid carboniferous 327 ma strike slip minas fault zone during the alleghanian orogeny fractures in the granite provide a record of several deformational and hydrothermal events with distinct mineral assemblages early sodic alteration produced albitisation of feldspar and riebeckite and tourmaline veins the 18 o of albite and albitised granite 5 6 is similar to other regional granites suggesting a mantle source of albitising fluids nearby halite deposits are younger and thus not a source of na early chlorite veins were followed by potassic alteration and hydrothermal biotite and by diabase and lamprophyre dyke emplacement euhedral magnetite occupies new cross cutting fractures and vugs correlated with regional iron oxide carbonate sulphide

palaeoclimatic records of the loess palaeosol sequences of the chinese loess plateau whether during past climate stages or into a progressively warming world changes in precipitation constitute a key component of climatic change quantitative proxies for palaeo precipitation are relatively rare the magnetic properties of the windblown loess units and interbedded palaeosols of the famous chinese loess plateau provide key palaeo precipitation data for this populous monsoon dominated region the loess palaeosol sediments record rainfall totals directly complementing the oxygen isotope records of chinese speleothems these isotopic records predominantly reflect moisture source and hence large scale atmospheric circulation changes the two major asian monsoon systems appear to display antiphase behaviour dominance of the indian summer monsoon system seems associated with minimum precession maximum northern hemisphere summer heating dominance of the east asian summer monsoons with maximum precession at 2 8 ma more intense development of the east asian winter monsoon initiated major increases in dust deposition rates and formation of relatively unweathered loess layers glacial stage loess units then interleaved with interglacial interstadial stage palaeosols throughout the quaternary period decoupling of the loess palaeosol rainfall records from the chinese cave records of moisture source shows that the indian and east asian monsoon winds were continuously driven by precessional forcing while summer monsoonal rainfall was greatly suppressed during cool glacial stages the timing of these east asian climatic transitions the subsequent intensification of northern hemisphere glaciations and the association between monsoon circulation changes and north atlantic temperatures indicates a possibly leading global role for these monsoonal changes via alterations in the poleward distribution of heat and moisture

tectonic deformation and magmatism along the southern flank of the maritimes basin the northeastern cobequid highlands nova scotia distributed crustal scale faulting in the cobequid highlands in the middle devonian to carboniferous resulted from the oblique convergence of the meguma and avalon terranes in the northeastern cobequid highlands seismic reflection profiles show neoproterozoic and lower paleozoic rocks together with enigmatic foliated rocks overlying the early carboniferous fountain lake group the foliated rocks form the hanging wall of a north vergent thrust fault their protolith is inferred from petrography and geochemistry to be principally neoproterozoic rhyodacitic tuff and late paleozoic hypabyssal intrusions the age of thrusting is stratigraphically constrained to the late tournaisian mid visean and sericite from mylonite yielded a tournaisian k ar age of 352 8 ma the thrusting occurs at the base of a tectonic escape sheet and resulted from a restraining bend in the rockland brook master fault farther west where the rockland brook fault trends almost east west tournaisian extensional features include

a spatio temporal analysis of trends in northern hemisphere snow dominated area and duration 1971 2014 seasonal snow cover modulates water and energy budgets across large areas of the northern hemisphere previous research based on satellite imagery interpreted and curated by the rutgers university snow laboratory has identified significant negative and positive trends in annual snow covered duration and area at hemispheric and continental scales between 1971 and 2014 this study uses the same dataset to generate more detailed descriptions of spatial variations in these trends maps intraannual variations in sign statistical significance and strength and quantifies associations with latitude and elevation it also considers the limitations and uncertainties associated with a binary classification of this type and the implications for trend magnitudes of adopting alternatives to the conventional assumption of 100 0 actual fractional snow covered area in snow covered snow free spatial units at different stages of the snow season this prompts adoption of alternative terminology referring to snow dominated area and duration in response to questions about the dataset s veracity raised by some prior studies it discusses climatological factors of potential relevance in explaining spatio temporal trend patterns and considers how biases might possibly have been introduced as a result of extraneous influences

predictability of snow depth anomalies over eurasia and associated circulation patterns summary this study investigates the variability and predictability of snow depth anomalies over the eurasian continent at the end of winter as represented in 12 ensembles of general circulation model simulations performed at the european centre for medium range weather forecasts each ensemble includes nine integrations performed with the same prescribed sea surface temperature but started from time lagged initial conditions an empirical orthogonal function eof analysis shows that the leading eof of eurasian snow depth in march has a zonallyoriented dipole structure with a band of positive anomalies covering northem europe and siberia and negative anomalies over central europe the himalayas and north china a significant relationship is found between the positivehegative phase of this snow depth anomaly and warm cold el niiio southern oscillation events the positive phase of the snow depth eofl is associated with a wintertime circulation characterized by a strengthening of the westerly winds over europe and siberia in the upper troposphere this westerly anomaly is accompanied by negative zonal wind anomalies over eurasia around 3w n and positive zonal wind anomalies between the equator and 25 n over africa and south east asia a good degree of predictability is found in the snowrelated circulation anomalies considering 500 hpa height 850 hpa zonal wind and 200 hpa zonal wind the interannual variations of the ensemble mean fields show a correlation of 48 56 and 65 respectively with the corresponding observed anomalies over the eastern half 0 to 180 e of the northern hemisphere the tropical component of the zonal wind anomaly associated with snow depth eofl is strongly predictable it shows a marked persistence from winter to the early summer and affects the large scale circulation over south asia in the early and central periods of the monsoon season

re examining pluton emplacement processes abstract previous pluton emplacement studies have attempted to explain how space is made during pluton emplacement in fact the only means of making space during emplacement of mantle derived magmas in the crust are 1 lowering the moho or 2 outward displacement of the earth s surface other pluton emplacement mechanisms are material transfer processes mtps that do not increase the volume of the crust one frequently cited mtp for emplacement of concentrically zoned and ballooning plutons is ductile flow of wall rocks around the plutons the expected structures and total strains near such plutons are dependent on the three dimensional pluton shape the width of the deforming aureole whether the pluton is a piercing or non piercing diapir and in the latter case the number of body radii the pluton travels we have re examined a few such plutons and calculated the amount of material transfer caused by ductile flow in no case is more than 40 and in most cases only 15 35 of the required material transfer accommodated by wall rock flow the contact aureoles around these plutons are too narrow and or strains too low indicating that the plutons are predominantly discordant bodies with narrow 0 1 0 4 pluton radii concordant aureoles a comparison of strains in natural contact aureoles and those made in mechanical models of diapirs indicates that natural strains are at least an order of magnitude less than model strains we suggest that the similarities between models of diapiric ascent of spherical bodies and concentrically zoned plutons are superficial because the models are too simplistic instead we argue that the ascent and emplacement of magmas require multiple near field and far field mtps these mtps will show gradients with depth distance from the magma and with time rates of near field mtps must be rapid whereas far field rates are probably nearer to long term average rates of orogenic processes

igneous emplacement in a shear zone termination the biotite granite at strontian scotland deformed xenolith strain data together with other structural information indicate that the biotite granite body 90 sq km of the strontian complex scotland was emplaced in the extensional termination of a dextral transcurrent shear zone this shear zone is a splay of the major great glen fault which lies along the southern boundary of the granite siting of the shear zone splay was probably controlled by a a slight releasing bend in the great glen fault in this area and b a large pre existing asymetric synform in proterozoic metasedimentary country rocks which intersects the great glen fault trace at a high angle a model is proposed in which moine thrust caledonian compression at ca 435 ma activated the great glen fault dextrally dextral movements around the releasing bend detached a flat segment from the inside fault wall and the biotite granite was emplaced side ways at depths of about 15 km as a sheet into this extensional listric fault bounded cavity

pluton emplacement along an active ductile thrust zone piute mountains southeastern california interaction between deformational and solidification processes plutons that are emplaced synchronously with regional deformation offer the opportunity to understand the partitioning of deformation and metamorphism in time and space during orogeny the 85 ma east piute pluton of the eastern mojave desert is an unusually clear example of a syntectonic pluton it was emplaced during thrusting in the southern cordillera combined petrologic and structutal studies lead to empirical models for the dynamic interaction of magmatic and deformational processes during granitoid emplacement and final crystallization trace and major element and isotopic data suggest that closed system differentiation of a single magma batch was responsible for compositional variation granodiorite to leucocratic granite correlation between degree of chemical evolution of compositional units and intrusive sequence suggests that discrete melt segregation events punctuated fractional crystallization modeling of trace element data suggests segregation of monzogranite melts after 50 70 crystallization of the magma and segregation of leucocratic granite after about 80 crystallization deformation promoted segregation of melt fractions at discrete times during crystallization during final ascent and after the magma had crystallized sufficiently 50 70 to attain shear strength monzogranite liquid was incompletely segregated along the active thrust zone at the southern margin of the pluton at essentially the present crustal level and after about 80 crystallization the remaining leucocratic granite melts were more effectively segregated and migrated into thrust related extensional openings including tension gashes undeformed pegmatite and aplite dike arrays indicate that final crystallization coincided with final increments of shear zone movement solid state deformational fabrics and brittle synthetic thrusts that offset the pluton margin record sharp temperature decline during and after crystallization because plutons crystallize rapidly they can be used to estimate strain rates during orogeny thermal modeling suggests that the transition from rheological liquid to solid in the east piute pluton occurred during an interval of about 10 4 yr as final increments of ductile deformation coincided with final crystallization of evolved compositional units total strain recorded by fabric in the pluton apparently accumulated during this interval shear strains estimated from the s c fabric in the granodiorite unit and rotation of pegmatite filled vein arrays are on the order of 1 thus strain rates in the shear zone were on the order of 10 12 sec during crystallization of the pluton this corresponds to displacements of tens of centimeters per year these high strain rates suggest punctuated melt enhanced movement episodes during contractional orogeny

geochemical evolution of earliest carboniferous continental tholeiitic basalts along a crustal scale shear zone southwestern maritimes basin eastern canada abstract continental tholeiites were extruded locally within the extensional wrench maritimes basin from about 375 to 330 ma late devonian early carboniferous basalts of the early carboniferous diamond brook formation are up to 1 5 km thick and overlie a succession of predominantly felsic volcanic rocks reaching several kilometres in thickness the volcanic rocks and co genetic plutons occur along a crustal scale strike slip fault that facilitated the transport of relatively primitive magma resulting in basalts with high mg number ni and cr end 4 and relatively low tio2 v y and zr fractional crystallization of plagioclase and lesser clinopyroxene in the absence of iron oxide fractionation resulted in repetitive extrusion cycles hundreds of metres in thickness that show an upward increase in plagioclase phenocrysts or megacrysts and in tio2 and other high field strength elements hfses rare andesites are interpreted as products of partial melting of underplated gabbro the relatively primitive basalts resemble low ti basalts found in other continental flood basalt provinces and have trace element and isotopic characteristics that have been ascribed in the literature either to partial melting of or contamination of asthenospheric melts by subcontinental lithospheric mantle in the maritimes basin similar continental tholeiites were extruded intermittently over a 45 ma period high feot 12 normalised to 8 mgo suggests high potential temperature in the source mantle presumably within a mantle plume the youngest eruption products geochemically and isotopically resemble himu oib plume activity may have gradually migrated eastward from late devonian to permian from the maritimes basin through scotland to norway and north germany

late paleozoic strike slip faults in maritime canada and their role in the reconfiguration of the northern appalachian orogen major late paleozoic faults many with documented strike slip motion have dissected the ordovician devonian appalachian orogen in the maritime provinces of atlantic canada activity alternated between east west faults minas trend and ne sw faults appalachian trend nw se faults canso trend were probably conjugate to minas trend faults major dextral movement on faults with appalachian trend in total between 200 and 300 km began in the late devonian this movement initiated the maritimes basin in a transtensional environment at a releasing bend formed around a promontory in the laurentian margin and thinned the crust accounting for the major subsidence of the basin appalachian trend strike slip continued in the mississippian but was accompanied by major movement on e w minas trend faults culminating around the mississippian pennsylvanian boundary juxtaposing the meguma and avalon terranes of the appalachians close to their present day configuration however strike slip continued during the pennsylvanian permian interval resulting in transpressional deformation that reactivated and inverted earlier extensional faults a final major episode of transtension mainly sinistral occurred during the mesozoic opening of the atlantic ocean restoration of movements on these faults amounting to several hundred kilometers of slip explains anomalies in the present day distribution of terranes amalgamated during early paleozoic appalachian tectonism in the restored geometry the nashoba and ellsworth terranes of ganderia are adjacent to one another and the meguma terrane lies clearly outboard of avalonia a restored post acadian paleogeography not the present day geometry of the orogen should be used as a basis for reconstructions of its earlier paleozoic history

tectonic significance of synextensional ductile shear zones within the early miocene alacamdag granites northwestern turkey synextensional granitoids may have significant structural features leading to the understanding of the evolution of extended orogenic belts one of the highly extended regions the aegean region includes a number of metamorphic core complexes and synextensional granitoids that developed following the alpine collisional events the alacamdag area in northwestern turkey is one of the key areas where miocene granites crop out along the boundary of various tectonic units structural data from the early miocene alacamdag granites demonstrated two different deformation patterns that may provide insights into the development of granitic intrusions and metamorphic core complexes 1 steeply dipping ductile shear zones caused emplacement of syn tectonic granite stocks they include kinematic indicators of a sinistral top to the sw displacement this zone has also juxtaposed the izmir ankara zone and the menderes massif in the west and east respectively 2 gently dipping ductile shear zones have developed within the granitic stocks that intruded the schists of the menderes massif on the structurally lower parts kinematic data from the foliated granites indicate a top to the ne displacement which can be correlated with the direction of the hanging wall movement documented from the simav and kazdag metamorphic core complexes the gently dipping shear zones indicate the presence of a detachment fault between the menderes massif and the structurally overlying izmir ankara zone mesoscopic to map scale folds in the shallow dipping shear zones of the alacamdag area were interpreted to have been caused by coupling between ne sw stretching and the accompanying nw se shortening of ductilely deformed crust during early miocene times one of the ne trending shear zones fed by granitic magmas was interpreted to form the northeastern part of a sinistral wrench corridor which caused differential stretching between the cycladic and the menderes massifs this crustal scale wrench corridor the izmir balikesir transfer zone may have controlled the asymmetrical and symmetrical extensions in the orogenic domains the combination of the retreat of the aegean subduction zone and the lateral slab segmentation leading to the sinistral oblique slip tearing within the eurasian upper plate appears to be a plausible mechanism for the development of such extensive ne trending shear zones in the aegean region

strong interannual variation of the indian summer monsoon in the late miocene the modern asian monsoon system exhibits strong interannual variation which has profound environmental and economical impacts it has been well documented that the mean asian monsoon state underwent significant changes in the late miocene 11 5 ma ago but how the interannual variability of the monsoon climate evolved during this period is still largely unknown in this study a long term simulation of the late miocene with a fully coupled atmosphere ocean general circulation model echam5 mpi om at t31l19 resolution is used to explore the interannual variation of the indian summer monsoon ism in the late miocene the regional climate model cosmo clm with a higher spatial resolution 1 1 is further employed to better characterize the spatial patterns of these variations our results show that although the mean ism circulation is weaker in the late miocene runs its interannual variation is as strong as or even stronger than at present and the dominant periods 2 6 2 7 years are shorter than at present 3 4 8 4 years it is noticed that while the extratropical influence on the ism variability is weaker than present a persistent el nino southern oscillation with stronger than present interannual variability is observed in our late miocene run this may have maintained a strong interannual variation of the ism with a shorter period in the late miocene our findings do not only improve our understanding of the asian monsoon evolution in the late miocene but also shed light on the future changes in the interannual variability of the ism

hydrological and ecosystem response to abrupt changes in the indian monsoon during the last glacial as recorded by sediments from xingyun lake yunnan china abstract the indian summer monsoon ism is the major moisture source of precipitation in southwest china and plays an important role in regional environmental change and in economic and social development since abrupt changes of the ism can cause crop failures and flooding that impact the livelihood of a large population however with the exception of speleothem records abrupt changes of the ism during the last glacial are not well documented in terrestrial records here we present a sediment record from xingyun lake in yunnan province southwest china spanning the interval 36 4 ka bp to 13 4 ka bp 1 ka 1000 cal a which documents the occurrence of a series of millennial scale episodes which may reflect the abrupt weakening of the ism seven ams 14c dates from terrestrial wood fragments provide a robust chronology the results demonstrate that increases in the coarse sediment fraction 30 m correspond to increases in the concentration of pediastrum the grain size of magnetic minerals carbonate content and c n ratios which together indicate episodes of low lake level in addition pollen analysis indicates that quercus oak increased and that ferns decreased during intervals of abrupt weakening of the ism indicating a drier environment nine abrupt shifts to a low lake level are documented for the studied interval and three of them are correlative with heinrich events 1 to 3 our study supports the hypothesis that in response to the cold events in the north atlantic associated with massive iceberg influxes and the corresponding slowing down of atlantic meridional overturning circulation the mean latitudinal extent of the itcz shifted southwards as a result of an atmospheric teleconnection there was a corresponding decrease in precipitation associated with ism precipitation which caused reduced fluvial runoff in yunnan

the effects of natural environmental changes on sedimentation in lake kuttanen a small closed lake in finnish lapland a sediment core from lake kuttanen a small closed lake in finnish lapland was investigated to determine the effects of holocene water table changes aeolian activity and forest fires on sediment physical properties and sediment geochemistry sediment properties were examined by water content loss on ignition loi and dry matter sedimentation rate analyses sediment geochemistry was studied by determining the acid soluble accumulation rates of al ca cu fe k mg mn na p and zn the fe mn ratio was calculated to study changes in the redox potential and charcoal concentrations were measured to determine the occurrence of local and regional fires the sediment accumulation rate was determined using 14c and b activity measurements principal components analysis pca was used to examine variations within the data and intercorrelations among the variables after the isolation of the basin all the element accumulation values were high because of the erosional supply from the catchment before stable so

a tsunami ca 6300 years bp and other holocene environmental changes northern hawke s bay new zealand abstract sediment cores collected in a coastal lagoon a few kilometres east of wairoa northern hawke s bay new zealand were examined using sedimentological geochemical palynological and micropaleontological analyses a distinct short lived catastrophic saltwater inundation csi about 6300 years bp and possibly other minor marine incursions are preserved in the coastal estuarine to lagoonal freshwater sedimentary sequences which have been deposited in the last 6500 years the csi is characterised by a gravel unit that thins landward and decreases in particle size to sand within a sequence consisting mainly of brackish estuarine muds diatom assemblages indicate a marked change from the shallow brackish estuarine muds to marine gravels and sands to brackish estuarine muds the marine influence in the gravel and sand is also shown by the presence of marine dinoflagellates and a peak in na rb sedimentological chemical and paleontological in particular diatoms evidence indicates it is a csi we conclude that this was a tsunami and propose the most likely propagating mechanisms marine influence decreases upcore and totally freshwater conditions are evident in the upper section of the cores the geochemistry of the sediments mainly reflects the change in stratigraphy with distinct signatures for tephra na fe cr organic rich and peat units as br and the coarse gravel sand csi unit na rb cr fe but it is also indicative of changes in depositional environment the change in chemistry na rb in the csi event is indicative of a saltwater influence whereas a marked change in s content suggests a sudden change from brackish to freshwater conditions shortly after 4800 years bp another peak in s and br content about 3200 years bp may indicate another temporary change to brackish conditions

active deformation in the new guinea fold and thrust belt seismological evidence for strike slip faulting and basement involved thrusting the new guinea fold and thrust belt forms a 1000 km long mountain chain running the length of new guinea but its trend is oblique to the predicted convergence direction a large component of left lateral shear across the mountain belt is expected but geological evidence for such motion is ambiguous surface structures in the fold and thrust belt show mountain building by folding and thrusting supposedly thin skinned of pre pliocene continental shelf sediments although some evidence indicates that active faulting penetrates the basement we examine the active deformation of this mountain belt by using teleseismic long period p and sh waveforms short period p waveforms and p wave first motions to determine reliable focal mechanisms and source depths for the 18 largest earthquakes in the new guinea fold and thrust belt since 1964 eight thrust events with seismic moments m0 between 1017 and 2 1018 n m are distributed throughout the thrust belt at depths ranging from 0 5 to 45 km and have steeply dipping fault planes that strike parallel to surface structural trends six of the eight events are between 11 and 25 km deep the steep dips of nodal planes the depths of these earthquakes and the known thicknesses of the sedimentary section show that thrust faulting is not exclusively thin skinned i e confined above a shallow detachment surface but penetrates the crystalline basement at high angles most earthquakes in the western half of the thrust belt including the three largest earthquakes examined m0 5 1018 n m show strike slip faulting with the probable fault plane oriented east west so that displacement is left lateral the nine strike slip earthquakes account for almost 90 of the observed seismic moment in the period 1964 1985 and indicate a seismic slip rate of 5 25 mm a all but one of these strike slip earthquakes are shallower than the thrust earthquakes suggesting that east northeast convergence across the fold and thrust belt is accommodated by a decoupled system of strike slip and dip slip faults while the great height of the mountain belt is an obvious indication that crustal thickening is an important consequence of plate motion in new guinea seismological evidence suggests that translation by strike slip faulting may play a much greater role than previously recognized by analogy in older collisional orogens whose motions can be inferred only from remnant structures and not from seismicity strike slip faulting may have been equally important in accommodating convergence we estimate from seismic moments of earthquakes and from the volume of the mountains that deformation of the new guinea highlands may account for 5 20 of the total convergence between the pacific plate and australia in new guinea

deep seismic reflection data from the bay of fundy and gulf of maine tectonic implications for the northern appalachians three deep penetration seismic reflection profiles were collected off southwest nova scotia to determine the crustal structure and geometry beneath the avalon and meguma zones of the appalachian orogen in canada onshore geological features have been traced seawards using new gravity and magnetic anomaly maps the seismic data can also be correlated with the previous united states geological survey profile in the central gulf of maine two seismically distinct lower crustal blocks are identified the avalon and sable lower crustal blocks separated by a major north dipping reflection zone that cuts the entire crust the recognition of the sable block adds a fourth block to the three already identified in the canadian appalachians the sable block is overlain by the meguma zone the avalon zone overlies at least the northern part of the avalon lower crustal block although offshore extension of geological features is not unequivocal it appears that a north dipping reflection zone southwest of nova scotia m

magma emplacement in a thrust ramp anticline the gavorrano granite northern apennines italy 1 magma emplacement in the upper crust is often associated with crustal extension whereby space for intrusions is made by dilation along transtensive and strike slip faults the lenticular shape of several intrusions indicates that a further mechanism for magma intrusion is laccolith emplacement with roof uplift of the overburden additionally melts exploit rheological discontinuities e g sedimentary layering during their ascent we present an emplacement model for intrusion of the shallow level gavorrano granite northern apennine italy which is located at the core of an open anticline the shape of the intrusion and structural features of the host rocks are indicative of a synkinematic emplacement in a growing thrust anticline space was provided by the opening of dilatation zones at the core of anticline as a consequence of different amounts of translation between hanging wall and footwall units which were separated by evaporitic rocks these evaporitic units acted as major decollement layers analog models provide results in good agreement with the structural setting of the anticline and emphasize the possibility that melts filled the dilatation zone with the decollement layers further facilitating intrusion