taphonomy of two non marine lower cretaceous bone accumulations from southeastern england abstract two vertebrate accumulations in the non marine wealden group lower cretaceous of southeastern england show contrasting preservational styles bones from a high energy fluvial lag deposit have well developed abrasion characteristics while vertebrate materials sampled from low energy overbank sediments are less abraded but show some evidence of subaerial weathering

dinosaurs and other fossil vertebrates from the late jurassic and early cretaceous of the galve area ne spain abstract since 1950 diverse assemblages of mesozoic vertebrates have been described from the galve area teruel province ne spain more than fifty taxa have been noted including fishes crocodyliforms pterosaurs dinosaurs and mammals the galve fossil sites occur in an upper jurassic to lower cretaceous succession spanning some 30 myr divided into five formations representing marginal marine and continental settings with a tithonian early barremian regression and a transgression from the barremian onwards new discoveries include teeth of the hybodont shark lonchidion microselachos spinosaurine theropods eusauropoda and the dryosaurid valdosaurus the 30 myr succession shows some possible evolutionary shifts with a predominance of sauropods as herbivores in older strata and ornithopods commoner in younger beds there are some possible replacements among mammals in the latter part of the succession with trechnotheres such as spalacotheriids and dryolestoids dominant in the el castellar formation and multituberculates in the camarillas formation matching of the vertebrates from the galve succession with those from age equivalent units throughout europe shows close similarity with the purbeck wealden succession of southern england among others there are many similarities with dinosaur faunas from north america and africa but continent scale faunal differentiation had clearly begun

modern changes of the high mountain landscapes and glaciation in southern siberia russia by the example of the eastern sayan mountains the period of observations of glaciation of the munku sardyk mountain massif in siberia is one of the longest i e 155 years however the data obtained are scattered and not systematic the paper presents an integrated analysis of the materials collected since the first description by the explorer of siberian mountains g i radde istoriy 1896 and extended by peretolchin 1908 and komarov 1953 as well as by glaciologists maksimov 1965 arefiev and mukhametov 1996 the authors considered the current state of the glaciers and interaction of natural geosystems of the massif taking into account the nival glacial processes since the beginning of the current millennium regular observations have been conducted on the munku sardyk massif by the v b sochava institute of geography sb ras limnological institute sb ras and east siberian state academy of education the studies revealed the leading landscape forming factors and examined the landscape structure of the surroundings of the contemporary nival glacial geosystems with due regard for the manifestations of altitudinal zonation a medium scale landscape typological mapping was carried out presented are the quantitative parameters of the dynamics of the nival glacial geosystems obtained on the basis of modern remote sensing instruments gps measurements and surface laser scanning using gis analysis the stump and stem of larch detected in the valley of the bugovek river 300 m above the contemporary upper forest limit and 1330 m up the valley show that most likely there was no glaciation during the atlantic period 7000 7300 years ago the modern glacier complex has formed only during the last 4000 5000 years the trend of shrinkage of glaciers since the end of the little ice age can be traced especially in recent years the length and area of the open part of the glaciers have decreased by half from 0 68 to 0 34 km2 the presence of small forms of glaciation on the southernmost limit of the siberian glaciation 1500 m below the theoretical climate boundary suggests that this area can be considered a unique key site to identify trends in development of the mountain and nival glacial geosystems and provides an opportunity to built reconstructive and predictive models of development of mountain landscapes under the conditions of ever increasing anthropogenic influence

polyphase magnetization in lower carboniferous rocks of s scotland palaeomagnetic and tectonic considerations abstract lower carboniferous lavas and intrusives from the southern margin of the midland valley scotland have yielded a principal magnetization termed the b component with d i 192 12 95 5 9 this magnetization is thought to have formed essentially during the original cooling but evidence of low temperature mineralogical changes as well as the presence of dual polarity remanence structures suggest that the magnetization processes continued beyond the deuteric stage covering at least the time span of geomagnetic field inversions an overprinted magnetization the a1 component of inferred lower tertiary age has a mean direction of d i 188 49 95 3 5 this secondary magnetization is found principally in three sites two from silica veins and one from a basaltic neck located within the southern uplands fault zone at dunbar microscopic evidence suggests that the a1 overprint was acquired thermochemically through alpine tectonic re activation of the fault

palaeozoic palaeomagnetic results from scotland and their bearing on the british apparent polar wander path abstract palaeomagnetic studies of the lower and upper old red sandstone ors western midland valley indicate the presence of two principal remanence components ib and hb both components can be demonstrated to be of secondary post upper ors origin component ib compares with palaeomagnetic results from upper carboniferous permian dykes and sills in the midland valley whereas hb conforms to palaeomagnetic results from the overlying lower carboniferous lavas a combination of hb components from the lower upper ors and lower carboniferous lavas western midland valley yields a relative pole position near s14 and e322 which compares well with lower carboniferous data from the kinghorn and burntisland lavas eastern midland valley s14 and e332 from kinghorn the palaeomagnetic data can be demonstrated to be of primary lower carboniferous origin seen in conjunction with the british polar wander path the lower carboniferous poles reported here seemingly dissociate middle upper devonian and upper silurian lower devonian poles owing to the lack of magnetic age control in the middle upper devonian data base it is argued that the majority of middle upper devonian data from the british isles should be reconsidered as carboniferous magnetic overprints this carries the implication that any tectonic models based on middle upper devonian palaeomagnetic results should be considered highly suspicious

palaeozoic reconfigurations of north scotland based on palaeomagnetic results from orkney dykes abstract the camptonite and monchiquite dykes of the orkney islands intruding middle devonian sedimentary strata constitute two significantly different axes of magnetization the inferred older of these remanences has an inclination corresponding to an upper devonian to early carboniferous age while the inclination of the secondary magnetization is in line with the kiaman overprint repeatedly recorded in orcadian basin rocks however the unique palaeomagnetic property of these dykes is that both magnetizations have mean declinations of 170 i e the palaeomagnetic axes are rotated 20 anticlockwise with respect to the corresponding nw european reference fields the data represent vital new information for the discussion of transcurrent motions along the great glen fault it is concluded that the orkney dykes originated at a late stage of an acadian age sinistral megashear 600 km at a time when the northern highlands block was positioned to the south of the central highlands partial remagnetization of the dykes took place at an early stage of hercynian fault reactivation the present declination discrepancy of both primary and overprinted magnetizations was brought about by a hercynian dextral displacement on the great glen fault 300 km leading essentially to the present juxtaposition of the northern and central highlands

impact of glacier changes on ecosystem of proglacial lakes in high mountain regions of east siberia russia mountain lakes in east siberia have been studied for recent changes in water chemistry turbidity and diatom assemblages preserved in bottom sediments we performed a regional analysis of the relative effect of climate and glacier changes on change in diatom diversity and supply of meltware in proglacial lakes we analysed sediment records from east siberian glacier lakes using geochemical and diatoms proxies we found that dramatic changes in communities and abundance of diatoms and biogenic proxy could be induced by low nutrient concentrations in glacial lakes and high turbidity due to active degradation of glaciers and snow patches as a result of the global increase in temperature in the northern hemisphere our evidences show that diatoms have been gradually decreased since ca the 1880s a significant tendency towards diatom reducing occurred at high summer regional temperatures this tendency may be attributed to the fact that glaciers and snow patches thawed actively in east siberia during ca 1880 1958 which was induced by the beginning of the recent warming ca 1850 1860 and a long period of relatively warm regional climate from ca 1900 to 1960

glacier fluctuation in northern and high asia historical and methods perspective glaciers in asia occupy nowadays much smaller extents than those of the pleistocene but they still play an important role in alpine ecosystems e g shahgedanova 2002 glaciers also pose hazards to society and infrastructure with avalanches and glacial lake outburst floods being the most destructive of glacier related natural events richardson and reynolds 2000 jansk et al 2010 nie et al 2013 wang and zhang 2014 since the end of the little ice age lia glaciers have been retreating almost everywhere around the world and this process has dramatically accelerated during the recent decades fig 1 wgms 2013 however individual glaciers are behaving differently and some have advanced while most have been in retreat ipcc 2013 yao et al 2012 mountain glaciers are sensitive indicators of climate change e g dyurgerov and meier 2000 haeberli et al 2004 and to fully understand the connection between changing climate and glacier fluctuations all the variables of the glacier mass balance need to be assessed at the local and regional scale dowdeswell et al 1997 oerlemans 2005 one of the regions where information about glacier changes is still scarce is northern and high asia fig 1 largely because glaciers of the region are located relatively far from human settlements and some have only been found after the 1940s for example ivanov et al 2015 have provided the first inventory of glaciers in the barguzinsky ridge east of lake baikal russia in this issue at the same time continental glaciers of northern and high asia are located far from the main sources of moisture and are thus sensitive to climate change fujita 2008 kaser et al 2010 in this issue we have collected information about glaciers situated along a southwestnortheast transect from 77 e 32 n the western himalaya india to 128 e 65 n the orulgan range russia fig 2 and fed from different sources of moisture the north atlantic the arctic and the indo pacific air masses because glaciers in our focus area belong to different climate systems their systematic study across the whole region has the potential not only to assess the climate change at local and regional scales but also to reveal climate change patterns at a larger continental scale the papers of this issue cover a variety of glacier related topics methods studies glacier inventories current glacier dynamics and paleo reconstructions and are based on a range of data such as satellite imagery synoptic maps biogeochemical proxies from proglacial lake bottom sediments and meltwater streams pollen and oxygen isotope records from snow ice cores and high resolution seismic reflection data

thermal demagnetization of some carboniferous lavas for palaeomagnetic purposes summary thermal demagnetization of the natural magnetization of carboniferous basalts from scotland has successfully revealed the original direction of magnetization although the specimens had badly scattered directions at room temperature

orthogonal joint systems in the bergen area southwest norway and their regional significance abstract joint orientation measurements are reported from the bergen district southwest norway the prevailing joint systems form two near vertical near orthogonal sets striking preferentially nw se and ne sw the orientation of these fissure systems is consistent with fissure systems dissecting the surface formations precambrian to quaternary throughout britain and northwest france they also show general agreement with lineaments in southern norway as revealed by landsat imagery it is suggested that the orthogonal joint network represents a fundamental tectonic structure originally implanted into the mobile outer layer of the earth in precambrian time the network has been repeatedly reactivated throughout the earth s dynamic tectonic history it was probably formed in a shear regime caused by torsional deformation associated with rotation of large scale lithospheric units which is still operating today

glacial history of the kuznetsky alatay mountains field investigations showed that the leeward slopes across the kuznetsky alatay mountains also the windward slopes in the tigertysh ridge are intensively eroded by glaciers and represent the classical type of alpine type landscape accumulative glacial landforms are developed in all types of glacial valleys study of five valleys the karatas the lower and the upper tayzhasu perekhodnya the right source of the small kazyr rivers showed that four stadial moraine complexes can be identified these moraines are very different by their morphology they indicate the change of glaciation from large ancient valley glaciers to modern small cirque and slope glaciers in this article the first data are assessed about evolution of glaciers and climate in the kuznetsky alatay mountains from the last glacial maximum of late pleistocene between 26 500 and 19 000 20 000 years bp to nowadays on the basis of studies of glacial landforms sedimentology and biostratigraphy in the glacier inventory complied in 1970s early 1980s 91 glaciers were recorded in the kuznetsky alatay however some were erroneously identified as glaciers the review of the current changes of modern glaciation of the kuznetsky alatay is made on the basis of repeated photographs and direct field measurements of 30 glaciers 18 out of the 30 studied glaciers melted away completely their area decreased from 1 4 to 0 5 0 3 km2 not all glaciers strongly degraded large cirque glaciers have not changed significantly over the past 110 years the area of perennial snowfields in the kuznetsky alatay mountains had reduced by 90 over the century the timberline has risen by about 50 m and is currently located at 1220 1200 m a s l

vertebrates from the middle late cenomanian la cabana formation asturias northern spain palaeoenvironmental and palaeobiogeographic implications article i nfo the asturian la cabana formation middle late cenomanian in age has yielded a rich and diverse assemblage of vertebrate microremains the fauna consists of both marine and continental forms including chimaeroids various selachians and actinopterygians chelonians crocodilians plesiosaurs pterosaurs sauropod dinosaurs and marine squamates this mixed assemblage of autochthonous coastal and allochthonous continental elements comes mainly from a transgressive lag occurring near the base of the formation it also contains some remains which are probably reworked from older middle cenomanian deposits palaeontological taphonomic and sedimentologic data indicate a shallow platform and marine lagoon with addition of some continental elements a comparison with the late cenomanian vertebrate assemblage of charentes southwestern france shows numerous similarities between both areas some taxa only known from asturias and charentes e g the aigialosaur carentonosaurus suggest that the opening bay of biscay may have constituted a palaeobiogeographic area characterized by endemism during the mid cretaceous

the fossil vertebrates from lano basque country spain new evidence on the composition and affinities of the late cretaceous continental faunas of europe a newly discovered fossil locality at lano basque country has yielded a vertebrate assemblage of probably maastrichtian age comprising fishes amphibians reptiles and mammals it considerably enlarges our knowledge of the late cretaceous continental faunas of europe hitherto based on a much less complete record some taxa are recorded for the first time in europe and the fauna also contains the oldest known representatives of some groups amphisbaenians salamandrids the lan assemblage reveals an original fauna comprising both forms related to asian and north american groups and elements with gondwanan affinities

structure and origin of holocene cold events abstract the present interglacial the holocene spans the period of the last 11 700 years it has sustained the growth and development of modern society the millennial scale decreasing solar insolation in the northern hemisphere summer lead to northern hemisphere cooling a southern shift of the intertropical convergence zone itcz and a weakening of the northern hemisphere summer monsoon systems on the multidecadal to multicentury scale periods of more stable and warmer climate were interrupted by several cold relapses at least in the northern hemisphere extra tropical area based on carefully selected 10 000 year long time series of temperature and humidity precipitation as well as reconstructions of glacier advances the spatiotemporal pattern of six cold relapses during the last 10 000 years was analysed and presented in form of a holocene climate atlas hoclat see http www oeschger unibe ch research projects holocene atlas a clear cyclicity was not found and the spatiotemporal variability of temperature and humidity precipitation during the six specific cold events 8200 6300 4700 2700 1550 and 550 years bp was very high different dynamical processes such as meltwater flux into the north atlantic low solar activity explosive volcanic eruptions and fluctuations of the thermohaline circulation likely played a major role in addition internal dynamics in the north atlantic and pacific area including their complex interaction were likely involved

holocene glacier fluctuations and climate changes in the southeastern part of the russian altai south siberia based on a radiocarbon chronology abstract this study investigates glacier dynamic and climatic variations in the southeastern part of the russian altai se altai during the last 7000 years recent glacier retreats and ice melting in moraines has led to exhumation of organic material allowing the possibility of radiocarbon dating we report here 57 new radiocarbon dates from wood remains buried by moraines and from proglacial forefields from peat layers and lacustrine sediments that cover moraines from dead trees at the upper tree limit and from rock glaciers on trough slopes from six glacial valleys in the north chuya range se altai such a numerous dataset for the vast but unified in neotectonic and climatic conditions area is presented for the first time the history of research in the altai together with 62 previously published radiocarbon ages mainly of fossil soils and peat layers in the foot of the ranges in se altai they form the basis for understanding the relative magnitudes and timing of the most important glacial and climatic events of se altai new data refute the traditional concept of the russian altai holocene glaciations as a consecutive retreat of the late wurm glaciers and argue their complete degradation at the head of trough valleys at least 7000 cal years bp moraine complexes of three holocene glacial stages are morphologically expressed in trough valleys of the north chuya range they correlate with three identified periods of glacial advances from 4900 to 4200 cal years bp akkem stage from 2300 to 1700 cal years bp historical stage and in the 13th 19th centuries little ice age lia or aktru stage the coincident extremes of lowering temperature and increasing precipitation during the akkem stage led to abrupt glacier advances and forming of the most remote moraine complexes downstream in the valleys following glacier advances had distinctly smaller magnitudes in addition to the radiocarbon data the time limits of the historical stage were defined more precisely using dendrochronological and archaeological data from scythian burials of pazyryk culture in se altai repeated forest regrowth in the presently glaciatiated area indicates significant retreat or even complete glacier degradation during interstage warming the decreases of glacier length in the following stages argues for intensification of aridity in the se altai during the second half of the holocene the thermal minimum in the middle of 19th century the greatest in the last millennium did not positively influence the mass balance of glaciers which also supports this conclusion

paleomagnetism of paleozoic strata brabant and ardennes massifs belgium implications of prefolding and postfolding late carboniferous secondary magnetizations for european apparent polar wander paleozoic carbonate rocks of the brabant massif namur basin and dinant synclinorium belgium are characterized by two secondary late carboniferous magnetizations of uniform reverse polarity a postfolding low unblocking temperature 300 375 c component lt and a prefolding high unblocking temperature 400 550 c component ht in the namur basin lt magnetizations postdate late westphalian deformation 305 ma in the dinant synclinorium ht magnetizations predate early westphalian deformation 316 ma lt magnetizations for the combined brabant massif and namur basin sites give a south paleopole at 42 3 s 339 6 e dp 1 9 dm 3 8 consistent with the european cratonic reference the lt magnetizations in the dinant synclinorium give a paleopole at 36 2 s 321 0 e dp 2 4 dm 4 7 the ht magnetization gives paleopoles at 34 1 s 333 4 e dp 2 6 dm 5 1 brabant and namur and at 25 9 s 321 5 e dp 3 5 dm 6 8 dinant synclinorium declinations indicate 15 clockwise rotation of the dinant synclinorium with respect to the brabant massif after acquisition of the lt magnetization devonian red beds yield near univectorial apparent synfolding magnetizations of distributed unblocking temperature that we interpret as artifacts of the remanence acquisition or deformation processes the ht paleopole for the brabant massif is indistinguishable from other early late carboniferous european paleopoles and is similar to poles interpreted to be derived from remagnetizations in the british isles age constraints on the time of remanence acquisition of secondary magetizations allow a refined calibration of the european apparent polar wander path inclinations of the lt and ht components indicate about 6 8 700 km northward motion during the late carboniferous

multicomponent magnetizations in the foyers old red sandstone northern scotland and their bearing on lateral displacements along the great glen fault summary the foyers sandstone a constituent of the old red sandstone of northern scotland located on the eastern flank of the great glen fault has yielded a multicomponent palaeomagnetic structure the principal magnetization called the b component with in situ mean direction d i 185 8 ag5 2 7 post dates the local mid devonian acadian tectonic event but this direction corresponds well with characteristic directions displayed by devonian and lower carboniferous rocks of scotland the most significant overprinted component the a2 magnetization with in situ mean direction d i 194 27 ag5 4 lo has a more patchy occurrence than the b remanence the strongest development of a2 being observed at sites that are situated close to the great glen fault zone the a2 direction is consistent with a hercynian age a third magnetization the a1 component of suggested lower tertiary age has been found at one of the sites close to the fault zone the a2 and b remanences support previously proposed declination discordances in corresponding magnetizations across the great glen fault it is concluded that the foyers sandstone developed its multicomponent magnetization through repeated tectonic events on the great glen fault in acadian hercynian and alpine times respectively

glaciers of the levaya sygykta river watershed kodar ridge southeastern siberia russia modern morphology climate conditions and changes over the past decades kodar ridge 57 n 118 e southeastern siberia is a glaciarized mountain area of inner asia here we have studied areal changes of glaciers and mid summer snow cover in the levaya sygykta river watershed area 650 km2 60 of total ice cover we used 1 50 000 1 100 000 topographic maps landsat tm 1995 etm 2001 2002 high resolution cartosat 1 2009 and worldview 2 2013 imagery two digital elevation models dems and field survey data to quantify the areal changes of the glaciers since the end of the little ice age lia to 2013 in 2013 the exposed area of 18 small glaciers from 0 02 to 0 88 km2 in the study area was 3 917 0 064 km2 and volume 255 106 m3 between the lia maximum and 2013 the area has been decreased by 61 with rate of 0 377 a 1 the data available today suggest the areal shrinkage of kodar glaciers from the lia seems to be larger than elsewhere in siberia the rate of area decrease in 1995 2001 was five times greater than in 1850 2013 and in 1850 1995 1 7 times less than in 1850 2013 using regional climatic data we have found that climate conditions obviously stimulated glacier mass loss over the past at least 60 years the increased variability of absolute and relative changes in 1995 2013 was due to influence of local factors on the overall climate driven deglaciation trend comparison of two dems has showed that between 1970 and 2009 ice surfaces of 12 tested glacier tongues have been lowered on average by 29 15 m with a rate of 0 75 m a 1

late cretaceous campanian actinopterygian fishes from the kristianstad basin of southern sweden although a diverse range of aquatic vertebrates are documented from the upper cretaceous mid campanian marine strata of the kristianstad basin in southern sweden only chondrichthyans and marine amniotes have been described in detail to date in contrast coeval actinopterygians are virtually unreported yet their remains are extremely abundant at most sampled localities a comprehensive assessment of these fossils has identified the first late cretaceous actinopterygian fauna from the fennoscandian shield incorporating indeterminate lepisosteids the durophagous pycnodontid anomoeodus subclavatus the predatory pachycormid protosphyraena sp a large ichthyodectid pachyrhizodontids resembling pachyrhizodus the enchodontid enchodus cf gladiolus and indeterminate small teleosts these taxa are diagnosed mainly from isolated teeth and scales implying substantial taphonomic loss prior to burial moreover the prolific recovery of actinopterygian skeletal remnants in recent excavations suggests that historical collecting biases rather than ecological paucity have contributed to their under representation in the swedish cretaceous record palaeobiogeographically the kristianstad basin actinopterygians show compositional resemblance to assemblages from the northern european platform and the western interior seaway of north america advocating distributional communication across the boreal proto atlantic ocean

pollen based reconstructions of vegetation and climate changes during the late holocene in the southern altai mountains we here preset a result of high resolution pollen data of a lacustrine peat sediment core from yushenkule yskl peat southern altai mountains northwestern china we aim to reconstruct the palaeo

inventory of nival glacial geosystems in lake baikal area east siberia russia glaciers in lake baikal area were plotted on topographic and tourist maps but often big perennial snow patches were designated as glaciers a special study of these entities to classify them in one group or another was necessary recently published data of remote sensing satellite images of high resolution allow distinguishing a variety of snow and ice objects accurate to 0 5 m in identifying sustainable nival glacial formations it was necessary to measure the characteristic parameters of these objects and their boundaries using topographic maps satellite images and gps devices the gis project and the database of nival glacial formations for the quantitative analysis of the accumulated information have been created the glaciers of mountain ridges of east siberia significantly reduced in thickness for the last decades and their abrupt degradation is manifested in the last 5 10 years the main glaciers of the barguzinskiy ridge decreases with 0 002 km2 year 1 that is comparable with the reduction rate of the glaciers of the eastern sayan ridge but is less than of the representative of the kodar ridge the azarovoy glacier

a geomagnetic polarity timescale for the carboniferous the geomagnetic polarity pattern for the carboniferous is incompletely known but with the best resolved parts in the serpukhovian and bashkirian hence data from both igneous and sedimentary units are also used in an additional polarity bias evaluation in the tournaisian to mid visean interval polarity is mainly derived from palaeopole type palaeomagnetic studies allowing identification of polarity bias chrons seven polarity bias chrons exist in the mississippian mi1nb to mi4nb with an additional 33 conventional magnetochrons and submagnetochrons mi4r to mi9r the moscovian and gzhelian polarity is best resolved in magnetostratigraphic studies from the donets basin and the southern urals dispute about the reliability of these data is ill founded since an assessment of supporting data from palaeopole type studies suggests that these datasets currently provide the best magnetic polarity data through the pennsylvanian polarity bias assessment indicates a normal polarity bias zone in the kasimovian in the pennsylvanian there are 27 conventional magnetochrons and submagnetochrons pe1n to ci1r and one normal polarity bias chron pe8nb the kiaman superchron begins in the mid bashkirian with clear data indicating brief normal polarity submagnetochrons within the superchron the magnetochron timescale is calibrated using 31 u pb zircon dates and a quantitative bayesian based age scaling procedure

the tethys sea and the alpine himalayan orogenic belt mega elements in a new global tectonic system abstract analysis of meso cainozoic palaeomagnetic data for africa india and eurasia has led to the development of a new mobilistic alpine plate tectonic model characterized by a hierarchical system of plates in relative rotation the new model which discounts seafloor spreading implies that there have been no significant palaeogeographic changes in the overall distribution of continental and oceanic regions the mid oceanic ridges are interpreted as transpressive tectonic features caused by rotation of megaplates containing both continental and oceanic crust the isostatic uplift due to crustal lithospheric thickening giving rise to the general ridge topography as well as to the ridge parallel structural grain the new plate tectonic theory gains strong support from a variety of geophysical geological and palaeoclimatological evidence and several observations that have remained enigmatic or awkward within the context of the orthodox model can be readily accounted for in the new tectonic framework the model maintains the tethys as a relatively narrow epicontinental sea which during its maximum extent stretched latitudinally from the caribbean across the central atlantic to se asia the alpine himalayan orogenic belt developed along the boundary of two megaplates in relative rotation which provided a transpressive tectonic regime the location of the plate boundary to the north of the mediterranean has important implications for discussion of mediterranean microplates for example it now seems that italy has been subjected to 10 15 of clockwise microplate rotation previous conclusions in favour of 30 40 of anticlockwise rotation are regarded as artefacts which arise from incorrectly linking the mediterranean region to the european palaeomagnetic frame instead of to the african one the model suggests further that the indo pakistani plate was closely tied to eurasia this challenges the conventional view that the peninsula was part of an alleged gondwanaland the new pre drift configuration implies that the indo pakistani plate rotated 135 clockwise at around the cretaceous tertiary boundary before redocking with asia in approximately its present relative orientation

structure of remanent magnetization and magnetic mineralogy of the cheviot lavas lower devonian northeast england abstract demagnetization data and magnetomineralogical results from the lower devonian cheviot lavas have revealed a complex remanence structure associated with extensive low temperature alteration of the primary magnetic oxides the original cooling magnetization has apparently been replaced by chemical remanences acquired in one or more dual polarity fields superposition of normal and reverse field components appears to have created fairly stable but what may be palaeomagnetically irrelevant directions which if not recognized or experimentally resolved may easily lead to incorrect conclusions evaluation of the total data base suggests that the characteristic palaeomagnetic axis is sub horizontal with an approximately n s declination the age range of this magnetization may vary from lower devonian to lower carboniferous the new experimental results throw into question some previous palaeomagnetic conclusions regarding the british lower old red sandstone lavas further critical study of the fossil magnetization of lower devonian rocks from britain should be on intrusive masses as such rocks are likely to have escaped at least the extensive surface oxidation and associated remagnetization complexities that have apparently developed in the extrusive suites

mid cenomanian vertebrate faunas of the western interior seaway of north america and their evolutionary paleobiogeographical and paleoecological implications abstract the western interior seaway wis was an epicontinental sea that extended north south through the middle of north america during the last half of the cretaceous linking the tethys sea to the south with the boreal paleo arctic ocean to the north aptian maastrichtian sedimentary deposits from the seaway crop out in the western interior basin of canada and the united states vertebrate remains are commonly well preserved and in certain stratigraphic units abundant the classic vertebrate fauna of the wis from the upper cretaceous niobrara chalk has been studied for 150 years but relatively little has been known of the seaway s earlier faunas until recent years studies of mid cenomanian vertebrate faunas particularly from lag deposits bonebeds and calcarenites in canada and the united states have significantly altered the previous picture of the overall biodiversity and biogeography of the wis during the mid cretaceous these mid cenomanian faunas include diverse fish assemblages of chondrichthyans cartilaginous fishes and osteichthyans bony fishes as well as various forms of tetrapods including marine turtles plesiosaurs and hesperornithiform and ichthyornithiform birds our compilation of faunas indicates that at least 70 vertebrate taxa are recorded from five mid cenomanian wis localities situated in alberta saskatchewan the black hills region of south dakota and wyoming kansas and colorado the faunas include 41 chondrichthyans 21 osteichthyans 10 non avian tetrapods and five avian taxa our study combined with previous faunal studies suggests that the combination of the following eight chondrichthyan species characterizes mid cenomanian time which has been referred to as the woodbinian age in the marine realm of north america ptychodus decurrens p occidentalis squalicorax curvatus cretodus semiplicatus carcharias amonensis c saskatchewanensis eostriatolamia tenuiplicatus and cretomanta canadensis this is the geologic time when non ptychodontid hybodonts became rare faunal components in most areas and when a number of other fish lineages particularly teleosts emerged and diversified many of these persisted into the early campanian or the niobrara age that followed the woodbinian therefore mid cenomanian time in the wis can also be characterized by the genesis of the niobraran fauna a significant radiation and diversification of fish taxa the five mid cenomanian wis localities highlighted in this study are separated by as much as 18 latitude a north south distance of more than 2300 km these faunas demonstrate some clinal trends such as more diverse faunas of benthic chondrichthyans mixed with dolichosaurid lizards to the south and a more diverse fauna of birds to the north however the faunas overall show strong taxonomic homogeneity particularly among many chondrichthyans that were cosmopolitan indicating that passage throughout the seaway as well as to both the boreal and tethys oceans was utilized these faunas also demonstrate high osteichthyan diversity in the northern waters of the wis which were once thought to have supported only a depauperate cold adapted fauna because of the surprisingly great diversity in vertebrate taxa ecosystem structure and dynamics of the wis during the mid cenomanian were unquestionably complex

strike slip terranes and a model for the evolution of the british and irish caledonides evidence is presented that many of the major strike faults in the british and irish caledonides were active as sinistral strike slip zones in the end silurian to pre mid devonian period some such as the highland boundary fault moved in this way at an earlier stage in the ordovician these data allow the caledonian rocks lying between the laurentian miogeocline whose basement is represented by the lewisian moine and possibly the dalradian and the gondwanaland miogeocline midland platform and welsh basin to be re analysed as a group of disorganized terranes which originated to the southwest in north america and southwest europe africa prior to the silurian the highland border terrane and northern belt terrane are interpreted as duplicated pieces of a mid ordovician sequence which was a back are to northwest subduction the midland valley terrane is interpreted as a slice of laurentian foreland onto which ophiolites were obducted in the lower ordovician but which became the basement of a continental margin arc to northwest subduction in the mid ordovician the cockburnland terrane is inferred to be part of the same arc repeated and then broken up and dispersed by continuing strike slip the connemara terrane is regarded as an allochthonous piece of the dalradian miogeocline and the south mayo terrane as a remnant of an early ordovician arc and fore arc which in mid ordovician times became a back arc marginal basin to northwest subduction the lake district wexford terrane is part of an arc to southeast subduction under gondwanaland whose activity climaxed in the mid ordovician the central terrane is interpreted as a silurian overstep assemblage which blankets the junction between laurentian and gondwanaland derived oceanic terranes and therefore iapetus is regarded as an ordovician ocean which closed prior to the silurian the model suggests that at the end of the silurian a clockwise rotating gondwanaland having carried laurentia into collision with baltica broke free and created a major sinistral strike slip zone which disrupted the ordovician palaeogeography in the british isles north american sector of iapetus

reconstruction of glacier fluctuations in the east sayan baikalsky and kodar ridges east siberia russia during the last 210 years based on high resolution geochemical proxies from proglacial lake bottom sediments we have presented results of study of bottom sediments of the proglacial lakes enriched with meltwater of peretolchin glacier the east sayan ridge chersky glacier the baikalsky ridge and glaciers of the kodar ridge bottom sediments formed from the end of the little ice age to 2013 were investigated with time resolution in year season using x ray fluorescence with synchrotron radiation and inductively coupled plasma mass spectrometry depth age models of the cores were estimated from year laminate layers using 210pb and 137cs chronology intense glacier thawing was calculated from the amount of clastic matter supplied by glacier meltwater into proglacial lakes a high content of some elements was closely associated with clastic material e g rb zr nb y or th in bottom sediments and most likely these elements affected the intensity of glacier melting we have defined three periods in significant increase of glacier flow melting during the last 210 years the first period ca 1800 1890 supply of suspended material by meltwater into lake ekhoy the east sayan ridge and lake preobrazhenskoe the kodar ridge was not intense until 1850 and 1875 respectively however the rate of meltwater supply into lake izumrudnoe the baikalsky ridge was high during the little ice age and it is likely attributed to local moisture from lake baikal the regional glacier water balances were most likely positive during the second period ca 1890 1940 the third period ca 1940 till present was characterised by moderate melting rate of glaciers located on the kodar and baikalsky ridges in contrast to peretolchin glacier that demonstrated the highest rate of melting and changes in outlines during this period

magnetization history of the upper silurian dingle group sw ireland summary the dingle group a continental upper silurian redbed succession in sw ireland has yielded a multicomponent palaeomagnetic record the oldest magnetization retrieved the b component with in situ mean direction of d i 191 9 k 40 95 3 6 n 41 post dates the local late silurian mid devonian acadian tectonic deformation and is in very good agreement with the prevailing remanences in other caledonian rocks of western ireland an overprinted a component with in situ mean direction d i 194 16 k 53 95 3 1 n 41 is about as prevalent as the b component and was probably acquired in late palaeozoic kiaman times by comparison with other published data including a positive fold test for corresponding magnetization of upper silurian redbeds in clare island it is concluded that the flat lying b field relative to britain and ireland was in existence at least from the late silurian to late middle carboniferous i e covering a minimum time span of 100 m yr