late quaternary tephrochronology of sweden a review abstract studies of late quaternary sediments in south and central sweden have yielded a detailed tephrochronology for the last glacial interglacial transition lgit ca 15 000 10 000 cal yr bp and the holocene more than ten tephra layers have been detected and geochemically characterised the most widespread tephra from the lgit is the rhyolitic phase of the vedde ash ca 12 000 cal yr bp which has been found in lacustrine sediments and marine clays south of the younger dryas moraines in south sweden other horizons from the lgit identified to date include the borrobol tephra ca 14 400 cal yr bp the hasseldalen tephra ca 11 500 cal yr bp the 10 ka askja tephra ca 11 300 cal yr bp and the hogstorpsmossen tephra ca 10 200 cal yr bp the most significant holocene isochrones are hekla 4 ca 4260 cal yr bp hekla selsund kebister ca 3750 cal yr bp hekla 3 ca 3000 cal yr bp and askja 1875 two new late holocene tephra horizons the stomyren tephra ca 2100 cal yr bp and the gullbergby tephra ca 2700 cal yr bp were identified in single sites and are so far less valuable as marker horizons but are potentially important for the future

the variation of temperature with time and hydrocarbon maturation in sedimentary basins formed by extension abstract when a sedimentary basin is formed by extension both the subsidence history and the temperature gradient can be calculated hence the time temperature history of any stratum can be obtained three types of behaviour occur the temperature of material which never reaches depths greater than about 4 km increases at all times the time temperature history of material which finally sinks to greater depths reaches a maximum during the subsidence history the time at which this maximum occurs decreases as the depth increases at greater depths the maximum temperature occurs at the time the basin is formed the time temperature history is then used to calculate lopatin s maturation index for each stratum as a function of time and the index plotted as a function of depth and time for different amounts of extension the maximum temperature at a given depth and hence lopatin s index is almost independent of the amount of extension when the age of the basin is greater than about 150 ma similar calculations taking account of sediment compaction show the same behaviour though the maturity of the material at a given depth is increased because both lopatin s index and its calibration are empirical it is important to develop new maturation indices based on individual molecular reactions whose activation energies can be determined in the laboratory

optically stimulated luminescence osl dating of coastal aeolian sand accumulation in sanday orkney islands scotland optically stimulated luminescence osl dating of sand has been used to identify periods of enhanced aeolian activity at two coastal archaeological sites in orkney that coincide with periods of holocene climatic deterioration recorded elsewhere in both scotland and w europe areas of tofts ness sanday were settled from the neolithic abandoned in the late neolithic early bronze age reoccupied and permanently abandoned in the iron age sand layers above the neolithic soils have been osl dated to about 4000 bp correlating well with a period of increased aeolian activity elsewhere in w europe osl dating of aeolian sands above midden deposits and a bronze age burial at lopness on sanday suggest dune development by 3000 bp although both sites also contain sand that was deposited during the little ice age several possible mechanisms may have contributed to an increase in aeolian activity during the holocene that led to the abandonment of these sites although volcanic eruptions in iceland cannot be disc

frost rings in trees as records of major volcanic eruptions new data about climatically effective volcanic eruptions during the past several thousand years may be contained in frost damage zones in the annual rings of trees there is good agreement in the timing of frost events and recent eruptions and the damage can be plausibly linked to climatic effects of stratospheric aerosol veils on hemispheric and global scales the cataclysmic proto historic eruption of santorini thera in the aegean is tentatively dated to 1628 26 bc from frost ring evidence

weak faults rotten cores earthquakes are triggered when crustal deformation produces displacements along fault zones the rock in these zones is found to be weaker than adjacent material but what are the mechanisms of this loss of strength in his perspective holdsworth 1 discusses how recent studies of exposed ancient fault zones combined with laboratory analyses are revealing that rock properties at the grain scale can determine the large scale behavior of crustal deformation 1 http www sciencemag org cgi content full 303 5655 181

age and impacts of the caldera forming aniakchak ii eruption in western alaska the mid holocene eruption of aniakchak volcano aniakchak ii in southwest alaska was among the largest eruptions globally in the last 10 000 years vei 6 despite evidence for possible impacts on global climate the precise age of the eruption is not well constrained and little is known about regional environmental impacts a closely spaced sequence of radiocarbon dates at a peatland site over 1000 km from the volcano show that peat accumulation was greatly reduced with a hiatus of approximately 90 120 yr following tephra deposition during this inferred hiatus no paleoenvironmental data are available but once vegetation returned the flora changed from a cyperaceae dominated assemblage to a poaceae dominated vegetation cover suggesting a drier and or more nutrient rich ecosystem oribatid mites are extremely abundant in the peat at the depth of the ash and show a longer term increasingly wet peat surface across the tephra layer the radiocarbon sample immediately below the tephra gave a date of 1636 1446 cal yr bc suggesting that the eruption might be younger than previously thought our findings suggest that the eruption may have led to a widespread reduction in peatland carbon sequestration and that the impacts on ecosystem functioning were profound and long lasting

a new early holocene cryptotephra from northwest scotland clarification of the temporal relationships amongst records of environmental change is dependent on accurate timescales event markers such as tephra layers are extremely important for constraining chronologies and providing tie points in this report we present evidence of a previously unknown early holocene icelandic cryptotephra from a lake in northern scotland the an druim tephra the calibrated radiocarbon age of 9560 cal yr bp for this new cryptotephra makes it an important addition to the suite of cryptotephras now recorded from the last glacial termination and early holocene in northwest europe in addition we report evidence in support of a younger borrobol tephra from lateglacial sediments of allerod age copyright 2005 john wiley sons ltd

the impact and significance of tephra deposition on a holocene forest environment in the north cascades washington usa high resolution palaeoecological analyses stratigraphy tephra geochemistry radiocarbon dating pollen and ordination were used to reconstruct a holocene vegetation history of a watershed in the pacific northwest of america to evaluate the effects and duration of tephra deposition on a forest environment and the significance of these effects compared to long term trends three tephra deposits were detected and evaluated mlf t158 and mlc t324 from the climactic eruption of mount mazama mlc t480 from a late pleistocene eruption of mount mazama and mlc t485 from a glacier peak eruption records were examined from both the centre and fringe of the basin to elucidate regional and local effects the significance of tephra impacts independent of underlying long term trends was confirmed using partial redundancy analysis tephra deposition from the climactic eruption of mount mazama approximately 7600 cal years bp caused a significant local impact reflected in the fringe location by changes to open habitat vegetation cyperaceae and poaceae and changes in aquatic macrophytes myriophyllum spicatum potamogeton equisetum and the alga pediastrum there was no significant impact of the climactic mazama tephra or other tephras detected on the pollen record of the central core changes in this core are potentially climate driven overall significant tephra fall was demonstrated through high resolution analyses indicating a local effect on the terrestrial and aquatic environment but there was no significant impact on the regional forest dependent of underlying environmental changes

local and regional scale impacts of the 74 ka toba supervolcanic eruption on hominin populations and habitats in india abstract the toba supervolcanic eruption of 74 000 years ago is argued to have devastated homo sapiens populations causing a human population bottleneck through a combination of rapid global climatic deterioration and ecological disruption following the widespread ash fall this dramatic eruption the largest in at least the last 2 million years is hypothesized to have shaped the genetic structure and diversity of human populations today past assessments of toba s human impacts however have been predominantly theoretical using archaeological and geological evidence from sites in india this study addresses toba s local scale impacts on hominin technology behavior demography and habitats in two valleys in india the jurreru and middle son valleys using paleoclimatological and volcanological data regional scale impacts throughout india are inferred a refugia hypothesis is presented that argues for variation in the scale of toba s impact throughout india driven by regional differences in monsoonal dynamics geography and topography areas of north west india the indo gangetic plain and parts of the deccan to the east of the western ghats are argued to have been the most affected whereas areas of southern and eastern india may have preserved the largest refugia for hominin populations

gplates building a virtual earth through deep time gplates is an open source cross platform plate tectonic geographic information system enabling the interactive manipulation of plate tectonic reconstructions and the visualization of geodata through geological time gplates allows the building of topological plate models representing the mosaic of evolving plate boundary networks through time useful for computing plate velocity fields as surface boundary conditions for mantle convection models and for investigating physical and chemical exchanges of material between the surface and the deep earth along tectonic plate boundaries the ability of gplates to visualize subsurface 3 d scalar fields together with traditional geological surface data enables researchers to analyze their relationships through geological time in a common plate tectonic reference frame to achieve this a hierarchical cube map framework is used for rendering reconstructed surface raster data to support the rendering of subsurface 3 d scalar fields using graphics hardware accelerated ray tracing techniques gplates enables the construction of plate deformation zones regions combining extension compression and shearing that accommodate the relative motion between rigid blocks users can explore how strain rates stretching shortening factors and crustal thickness evolve through space and time and interactively update the kinematics associated with deformation where data sets described by geometries points lines or polygons fall within deformation regions the deformation can be applied to these geometries together these tools allow users to build virtual earth models that quantitatively describe continental assembly fragmentation and dispersal and are interoperable with many other mapping and modeling tools enabling applications in tectonics geodynamics basin evolution orogenesis deep earth resource exploration paleobiology paleoceanography and paleoclimate

dates of holocene icelandic volcanic eruptions from tephra layers in irish peats tephra from historic and prehistoric eruptions of oraefajokull and hekla iceland have been found in irish peats using a series of stratigraphically related high precision radiocarbon measure ments the date of a known age eruption has been satisfactorily estimated based on the same techniques the calendrical date of the hekla 4 eruption has been estimated as 2310 20 bc

a model for the formation of intracratonic sag basins summary intracratonic sag sedimentary basins occur in the middle of stable continental or cratonic blocks they are rarely fault bounded although strike slip faulting can occur within them a simple model for the development and evolution of these basins is proposed the mechanism is driven by mildly coupled convective down welling of the asthensophere beneath the lithosphere initially a rapid alteration of the mantle convective system causes a descending plume to develop a depression which can be of the order of 600 m can be formed at the earth s surface this depression when loaded with sediment will form a sedimentary basin of the order of 2 5 km thick if the convective downwelling remains a period of thermal cooling of the lithosphere occurs which is similar to the thermal cooling subsidence phase of passive continental margins this thermal cooling occurs because of the thermal anomaly temperature decrease beneath the lithosphere caused by the convective downwelling if a change of convective pattern occurs and the descending plume is removed the basin will undergo uplift and erosion whereby a significant thickness of the sedimentary basin can be removed the ordovician and silurian tectonic development of the canning basin western australia appears to be well explained by this model

mantle induced subsidence and compression in se asia since the early miocene rift basins developed extensively across sundaland the continental core of southeast asia since the eocene beginning in the early miocene basins in southern sundaland experienced widespread synchronous compression inversion and marine inundation despite a large drop in long term global sea level the mechanism for this large scale synchronous regional sea level rise basin inversion and subsidence is not well understood and contrary to expectations from traditional basin models and eustatic sea level trends we present geodynamic models of mantle convection with both deformable and rigid plate reconstructions to investigate this enigma models suggest that a slab stagnates within the transition zone beneath southeast asia before the miocene the stagnant slab penetrated through the 660 km mantle discontinuity during the early miocene and formed a slab avalanche event due to continuous subduction and accumulation of negatively buoyant slabs this avalanche may have induced large scale marine inundation regional compression and basin inversion across southern sundaland we argue mantle convection induced large scale basin compression in contrast to conventional plate margin induced compression this suggests mantle convection may exert a much stronger control on surface processes than previously recognized

multi phase reactivations and inversions of paleozoic mesozoic extensional basins during the wilson cycle case studies from the north sea uk and the northern apennines italy

replicated proxy climate signals over the last 2000 yr from two distant uk peat bogs new evidence for regional palaeoclimate teleconnections ombrotrophic peat is an established source of proxy climate data but previous records have been produced by different methods and have been difficult to compare high resolution plant macrofossil analysis has been applied to a lowland raised bog at fallahogy northern ireland and a montane blanket bog moine mhor in the cairngorms scotland although the bogs are 300 km apart and differ floristically the results demonstrate parallel responses to climatic forcing especially that of the little ice age this approach provides a powerful tool for reconstructing proxy climate records wherever suitable peat deposits exist in contrast to the ocean and ice core records these proxies are from a terrestrial source and related to climate changes on land over most of the holocene

some aspects of the organic geochemistry of petroleum fluids the most important influences on the compositions of petroleum fluids are in many cases the composition of a petroleum sample may allow the depositional environment of its source rock and its temperature history before and after expulsion to be determined this information assists the search for more petroleum in a region we suggest that this approach should be used more frequently to validate models of petroleum generation and migration in the second part of the paper we discuss the origin and nature of the differences in petroleum composition which are frequently found within individual petroleum reservoirs petroleum accumulations in permeable reservoirs are normally found to be inmechanical equilibrium and verticalchemical equilibrium this is manifested by constant subsurface fluid density at any given depth across the accumulation and increases in subsurface density with depth known as gravitational segregation however even in permeable reservoirs lateral differences in composition inherited from the reservoir filling process are not totally eliminated by mixing processes such as diffusion and convection thus lateral chemical equilibrium is often not achieved and lateral compositional variations are observed in present day oil and gas reservoirs these observations are justified in terms of order of magnitude estimates for the rates at which reservoirwide mixing occurs a case history is presented

tephrostratigraphy of an loch mor inis oirr western ireland implications for holocene tephrochronology in the northeastern atlantic region twelve definable cryptotephra layers younger than c 8600cal bp are reported from lacustrine core material taken from an loch mor inis oirr aran islands western ireland the geochemistry of these shard layers which represent more holocene tephras than previously geochemically characterized from any european site outside the proximal volcanic influence of italy or iceland is presented of these tephras four may correlate with known iceland derived tephra horizons vo 1477 hi lairg a and h5 one appears to have two possible named correlatives hoy lairg b at sluggan bog n ireland another has a plausible correlative ad 860a but two others represent icelandic tephras apparently not previously reported on iceland itself including a tephra that has geochemistry very similar to hl ad 1104 but which dates to c cal ad 840 four tephras that date from the period c ad 40 1400 have a distinct geochemical signature that relates to jan mayen 750km to the northeast of iceland and some 1800km distant from an loch mor the results contribute substantially to the chronology of the sediments from an loch mor and at the international level to the tephrostratigraphy of the northeast atlantic region the well attested icelandic h4 tephra from a hekla eruption of c 4260cal bp was not recorded it is suggested that an loch mor lies south of its recordable distribution in this part of the northeast atlantic region taken together with work at other sites the findings point to a wealth of potential tephra isochrons in holocene deposits of the northeast atlantic seaboard it is clear also that calcareous lake sediments can be as fruitful a source of tephras as peats potential problems relating to dating and geochemical fingerprinting of tephra layers in individual sites are highlighted with reference to the lairg tephras as recorded in scotland and northern ireland and to the hoy tephra that has been described from orkney

seven tephra isochrones in scotland this paper reports the presence and geochemical characteristics of seven separate tephras in scotland that fell in ad 1510 and about 450 bp 2100 bp 3600 bp 3830 bp 5600 bp and around 6000 bp the results come from 14 peat bogs spread throughout the highlands and islands where 26 tephra deposits have been characterized using over 400 grain discrete electron probe micro analysis firstly tephras are identified and defined by major element characteristics at a reference site secondly tephras are linked between sites on the basis of geochemistry and dated informal names based on british sites are suggested for tephras not yet linked to precise sources in iceland despite some apparent variation in colour all analysed grains in these seven deposits are silicic or intermediate in composition sio2 57 this phenomenon does not appear to be an artifact of preservation for two reasons first small 40 m basic glass shards in peat bogs in northern iceland are found to have undergone minimal alte

the impact of high tephra loading on late holocene carbon accumulation and vegetation succession in peatland communities abstract peatlands are major terrestrial stores of carbon c of importance to the global climate system recent studies have made progress in understanding the climatic controls on the c cycle however important interactions between volcanic deposition and peatland c stores remain to be addressed this study uses a 3000 year peatland record from northern japan to examine the interactions between carbon accumulation vegetation community succession and volcanic ash deposition plant macrofossil and testate amoebae records are presented alongside records of total organic carbon nitrogen and phosphorous age depth models are developed using a bayesian approach with seven ams radiocarbon dates and two identified historical tephras from baitoushan ad 969 981 cal bp and hokkaido komagatake ad 1640 310 cal bp volcanoes results show that moderate to high tephra loading can shift peatland plant communities from sphagnum to monocotyledon domination this vegetation change is associated with increased peat humification and reduced carbon accumulation where tephra deposition and reworking has occurred the apparent rate of carbon accumulation can be halved while high tephra loading of the mire surface is sustained sphagnum species vary in their tolerance to tephra deposition after each ash fall sphagnum magellanicum disappeared from the plant macrofossil record whereas sphagnum papillosum showed apparent continuity of development through the 1856 94 cal bp ko c1 tephra high rates of carbon accumulation peaking at 100 g m 2 yr 1 2 3 times faster than the average for northern peatlands were recorded in the sphagnum communities that established after the cessation of tephra deposition and reworking from the ad 969 baitoushan ash fall b tm tephra this peak in c accumulation was coincident with a radical shift in mire nutrient cycling most probably caused by the interaction of s magellanicum with leachates from the underlying tephras the phase of high c accumulation continued for over 300 years offsetting the initial negative impact of the b tm tephra on peatland c accumulation these results suggest that management for ash tolerant sphagnum species could be a highly effective strategy for minimising volcanic disruption to peatland carbon accumulation the study also shows that consideration of volcanic impacts on peatlands is essential for development of more realistic terrestrial carbon balance models in volcanically active regions

why do continents break up parallel to ancient orogenic belts the frequently observed parallelism between rifts and the pre existing orogenic fabric of continents suggests that the inherited tectonic fabric of the lithosphere influences the rupture of continents we propose that the existence of a pervasive fabric in the lithospheric mantle induces an anisotropie strength in the lithosphere that guides the propagation of continental rifts subcrustal mantle mechanical anisotropy is supported by i the anisotropie strength of olivine ii an ubiquitous tectonic fabric in exposed mantle rocks and iii measurements of seismic and electrical anisotropy during major episodes of continent rifting parallel to orogenic belts ocean opening through rifting and continent break up is frequently related to the occurrence ofhotspots there is howevcr a discrepancy between hot spots acting as pin point sources of heat and the linear extent of rifts over thou sands ofkilometres moreover rifts tend to parallel pre existing orogenic fab

investigation of the environmental impact of remote volcanic activity on north mayo ireland during the mid holocene seven layers of microscopic tephra have been detected in ombrotrophic peat from western ireland a radiocarbon chronology suggests that two of the tephra layers were deposited around 4000 bp pollen fungal spores and testate amoebae have been analyzed from the peat immediately above and below the tephra layers these analyses provide information of changes in the landscape surrounding the bog and as well as conditions on the bog surface analysis of rates of change in these data has been employed to investigate the relative magnitude of environmental changes at the time of tephra deposition tephra deposition occurred at least 100 years after a major decline in pinus pollen and coincides with fairly stable conditions in the terrestrial environ ment more significant changes on the bog surface indicative of wetter conditions are associated with the timing of tephra deposition

non climatic factors and the environmental impact of volcanic volatiles implications of the laki fissure eruption of ad 1783 studies of the potential of icelandic volcanic eruptions to modify the environment of the british isles have primarily concentrated on the degree of induced climate change but models and temperatu

distal volcanic impacts on peatlands palaeoecological evidence from alaska abstract despite the fact that volcanic ash tephra layers are found preserved in peat deposits around the world comparatively little research has investigated the impacts of distal volcanic emissions on peatlands this study investigates the impacts of several late holocene volcanic eruptions on five peatlands in southern alaska using a palaeoecological approach testate amoebae analysis peat humification analysis and a basic analysis of plant macrofossil components were applied across 11 tephra layers changes in macrofossil and testate amoebae assemblages occur across several of the tephra layers the humification results were considered unreliable because of a methodological problem a finding which may have implications for other studies using this technique redundancy analyses on testate amoebae data show statistically significant changes associated with two tephras the most likely causes of the impacts are volcanic gases acidic precipitation or tephra derived leachates the finding that some tephras are associated with impacts whereas others are not may relate to the season of the eruption or meteorological conditions at the time of ash fall these results suggest the sensitivity of peatlands and peatland microbial communities to distal volcanic products and imply that changes in key palaeoclimatic proxies may be caused by a mechanism independent of climate change implications of the results for peat based palaeoclimatic studies are discussed as are possible directions for future research

early holocene volcanic ash fallout in the yammouneh lacustrine basin lebanon tephrochronological implications for the near east article i nfo a volcanic ash layer tyam 1 was identified in holocene sediments from the yammouneh paleo lake lebanon the ash layer consisted of colourless shards the major elemental chemistry of the glass as determined by electron microprobe analyses indicates a rhyolitic composition radiocarbon dating of detrital wood fragments located in the ash layer suggests an age of approximately 8 6 ka cal bp the timing of the layer and a chemical comparison with other published data suggest that tyam 1 likely originated from anatolia and likely corresponds to early holocene z3 z4 z5 tephras the preliminary results provided in this manuscript suggest a new stratigraphical and chronological marker for the continental records of lebanon and neighbouring regions

paleoreconstruction by biological markers abstract during diagenesis and conversion of the original lipid fraction of biological systems to petroleum hydrocarbons the following four basic events needed for paleoreconstruction can be monitored by biological markets 1 sourcing 2 maturation 3 migration and 4 biodegradation actual cases of applying biological markers to petroleum exploration problems in different parts of the world are demonstrated cretaceous and phosphoria sourced oils in the wyoming thrust belt can clearly be distinguished from one another by high quality source fingerprinting of biomarker terpanes using gas chromatography mass spectrometry identification of recently discovered biological markers head to head isoprenoids allows subtle source differentiation between oils from sumatra the degree of crude oil maturation in basins from california alaska russia wyoming and louisiana can be assessed by specific novel biomarker ratios 20s 20r sterane epimers field evidence from such interpretation is confirmed by laboratory pyrolysis of the rock an example of immature sumatra rock is given extensive migration is documented by biomarkers in several oils the effect of biodegradation on biomarker steranes and terpanes is exemlified in a california basin all biological marker results are consistent with the geological setting and add a new dimension in assisting the petroleum explorationist toward paleo reconstruction

a pioneer of precambrian geology boris choubert s fit of the continents across the atlantic 1935 and his insights into the proterozoic tectonic structure of the west african craton and adjacent areas abstract plate tectonics revolutionized the earth sciences during the 1960s and led to a fundamentally new view of tectonic processes inside mountain belts application of the new theory to pre permian and especially precambrian orogenic belts developed somewhat reluctantly during the 1970s and 1980s the present article presents and discusses the ideas of boris choubert 1906 1983 a french colonial geologist of russian origin which he first developed in 1935 he tried to test wegener s theory of continental displacement a forerunner of plate tectonics by applying it to paleozoic and precambrian orogenic belts around the atlantic a topic altogether neglected by wegener to achieve this he produced a fit of the continents across the atlantic which is almost identical to the famous 1965 fit of bullard et al starting from this paleozoic continental configuration he presented an inter continental synthesis of precambrian geology and discussed problems from a wide array of topics ranging from regional tectonics of the west african craton questionable precambrian fossils tillites and cap carbonates to the supposed origin of detrital diamonds in gabon and brazil he also provided probably the first precambrian plate reconstruction avant la lettre after his 1935 paper choubert worked for decades in africa and south america and had opportunity to test and refine his synthesis his example is a call addressed to present day geologists working on precambrian geology in africa and other regions to consult the old colonial literature which contains a wealth of factual information and theoretical inspiration which is still of interest today

towards a tephrochronology for the holocene of the north of ireland discrete layers of tephra have been found in both raised and blanket bogs in the north of ireland some of the layers have been identified to an icelandic source and in two cases specific eruptions of known radiocarbon age are suggested nine layers spanning the holocene are replicated in three lowland raised bogs one of the major layers has also been identified at a number of sites in two separate upland blanket peat systems and in a lake sediment

global tectonics and eustasy for the past 2 billion years abstract continental freeboard and eustasy as gauged by the relative position of the world shelf break with respect to sea level have varied by 250 m from today s ice free shelf break depth of 200 m during the past 600 ma assuming constant or uniformly accreting continental crust and ocean water volume in an ice free world sea level fluctuations can be attributed to variation in the world ocean basin volume caused by changes in either its area or its depth relative to the world shelf break an increase in volume and lowering of sea level occur as 1 the world ocean floor ages cools and subsides 2 accreting continents collide thicken and decrease in area and 3 poorly conductive continental platforms become thermally elevated due to a size induced stasis over the mantle conversely a decrease in the age of the world ocean floor attenuation of continental crust during rifting and an increase in continent number and mobility will reduce the world ocean basin volume and raise sea level theoretical sea level calculated from these principles correlates well with calibrated first order cycles of eustatic sea level change for the phanerozoic the record closely fits a simple model of retardation and acceleration of terrestrial heat loss during alternating periods of supercontinent accretion and fragmentation calibrated to sea level highstands successive first order marine transgressions and orogenic pangea regressions characterize a self sustaining 440 ma plate tectonic cycle for the late precambrian and phanerozoic the cycle can be recognized as far back as 2 ga from the tectonic evidence of continental collision and rifting recorded in global orogenic peaks and mafic dike swarms and may be related to major episodes of glaciation and evolutional biogenesis

mapping the upper mantle three dimensional modeling of earth structure by inversion of seismic waveforms a method is presented for the inversion of waveform data for the three dimensional distribution of seismic wave velocities the method is applied to data from the global digital networks international deployment of accelerometers global digital seismograph network the selected data set consists of some 2000 seismograms corresponding to 53 events and 870 paths the moment tensors of the earthquakes are determined through an iterative procedure which minimizes the corrupting influence of lateral heterogeneity a global model is constructed for shear wave velocity expanded up to degree and order 8 in spherical harmonics and described by a cubic polynomial in depth for the upper 670 km of the earth s mantle although no a priori information is incorporated the model predictions reproduce much of what is known about the dispersion of mantle waves for example high phase velocities for shields low velocities at ridges and a strong degree 2 pattern for rayleigh waves since the method makes use of complete waveforms overtone data are also included it is shown that the model is reproducible in that substantially the same model can be constructed from each half of the total data set considered independently the model shows that shields and ridges are major features in the depth interval 25 250 km the ridges of the southern pacific and the larger shields persist to 350 km but the southeast indian rise is underlain by a high velocity anomaly at this depth as is much of the mid atlantic ridge at 450 650 km the major features are a broad region of high velocities incorporating south america much of the south atlantic and parts of west africa a broad region of low velocities in the central and eastern pacific high velocities in the western pacific and a low velocity anomaly beneath the red sea and the gulf of aden in the absence of a crustal correction degrees 2 and 3 show a high positive correlation with the geoid paradoxically this is largely destroyed when the distribution in crustal thickness is taken into account spherical harmonic degrees 4 7 show a significant negative correlation

origin and emplacement of ophiolites ever since their recognition ophiolites have been a source of controversy although all workers have agreed upon their importance a number of conflicting schools of thought have become unified in the interpretation of ophiolite complexes as fragments of oceanic crust and mantle formed at spreading centers an expanded version of the penrose ophiolite definition is proposed herein called the ophiolite association taking into account rocks which bear upon the origin and significance of ophiolite complexes an ideal ophiolite association includes the following units from bottom to top 1 a crystalline basement and shallow water sedimentary sequence 2 a tectonic unit of thrust slices of continental margin and rise and abyssal sediments and or melange 3 a metamorphic unit as much as a few hundred meters thick generally with higher grade rocks over lower grade ones 4 ultramafic tectonite unit composed dominantly of multiply deformed peridotite dunite and minor chromitite 5 a cumulate complex ultramafic at the base grading to mafic or intermediate at the top 6 a noncumulus unit of varitextured gabbro and minor trondhjemite 7 a sheeted dike complex 8 an extrusive section of massive and pillowed flows and intercalated sediments 9 an abyssal or bathyal sediment sequence which may include radiolarian chert red pelagic limestone metalliferous sediments breccias and or pyroclastic deposits and 10 postemplacement deposits of laterite reef limestone or shallow marine or subaerial sediments this expanded ophiolite association allows greater precision in inferring original origin and emplacement some ophiolite complexes particularly in the tethys herein designated tethyan type exhibit units 1 2 3 and 4 whereas others particularly in the cordilleran belt herein termed cordilleran type lack units 1 2 3 and in places 4 the emplacement of the former probably occurred during collision of a passive margin with a subduction zone or incipient subduction zone emplacement of the cordilleran type generally is not clear cut the nature of the spreading center which produced a given ophiolite is indicated more clearly by the presence or absence of units 5 9 than by chemistry or mineralogy some ophiolite complexes lack complete sections and may have formed along transform faults others contain volcanic pyroclastic deposits instead of pelagic sedimentary sequence and probably formed within or near an arc several ophiolite complexes may have originated by conversion of a transform fault into a subduction zone such conversion may result from normal plate evolution or from major plate reorganization major times of ophiolite emplacements appear to correspond with global plate reorganizations

john tuzo wilson a canadian who revolutionized earth sciences john tuzo wilson 1908 1993 was one of the greatest canadian scientists of the 20th century his contributions to earth sciences leading the formulation of the theory of plate tectonics have revolutionized our understanding of how the planet earth works and evolved over the past 4 billion years this 50th anniversary special issue of the canadian journal of earth sciences is dedicated in honour of john tuzo wilson who inspired tens of thousands of students all around the world to study the earth this special issue contains 12 papers dealing with various aspects of the wilson cycle in the geologic record plate tectonics mantle plumes and how john tuzo wilson accepted continental drift and formulated the theory of plate tectonics the contributions have mostly been made by geoscientists who directly or indirectly associated with john tuzo wilson and have contributed significantly to the plate tectonics paradigm

effects of volcanic activity on mire development case studies from hokkaido northern japan field stratigraphy and macrofossil composition of four mires in hokkaido northern japan were investigated to test whether tephra deposition induces long term vegetation shifts macroscopic tephras of known origin ranging from 0 5 to 25 cm in thickness were found in two or more of the study sites allowing correlation of the stratigraphic development of the mires major peat types and position of macroscopic mineral layers were determined in the field and selected cores were analysed by quantitative macrofossil analysis some macrofossil groups and the content of unidentifiable organic matter showed changes in the vicinity of tephra layers but they did not indicate a clear response pattern of the vegetation or the decomposition dynamics of plant material mosses were expected to be most strongly affected by tephra deposition but even in cases where tephra fell on sphagnum dominated vegetation no fundamental shifts to new plant communities were found this suggests that disturbance by widespread tep

seismic tomography surface uplift and the breakup of gondwanaland integrating mantle convection backwards in time mantle density heterogeneities imaged using seismic tomography contain information about time dependent mantle flow and mantle structures that existed in the past we model the history of mantle flow using a tomographic image of the mantle beneath southern africa as an initial condition while reversing the direction of flow and analytically incorporating cooling plates as a boundary condition if the resulting backwards integrated model for structures is used as a starting point for a forwards convection model today s mantle can be adequately reconstructed if we do not integrate backwards more than than about 50 75 ma flow can also be reliably reversed through the mesozoic but only if instability of the lower boundary layer can be suppressed our model predicts that the large seismically slow and presumably hot structure beneath southern africa produced 500 700 m of dynamic topography throughout the cenozoic since 30 ma uplift has moved from eastern to southern africa where uplift rates are 10 m myr consistent with observations during the mesozoic the modeled topographic high is situated near gondwanaland rifting raising the possibility that this buoyant structure may have been involved with this breakup

measuring dynamic topography an analysis of southeast asia 1 theoretical models of dynamic topography generated by subducting slabs and consistent with the observed geoid predict 1 2 km of subsidence on wavelengths of 102 103 km the demonstrable existence of such subsidence has important implications for understanding sedimentary basin formation relative sea level changes as well as the earth s viscosity and density structure here we present the results of a combined analysis of subsidence data from oceanic marginal basins and their fringing continental shelves we have chosen to analyze a large area of southeast asia where dynamical predictions are believed to be well constrained by the history of subduction our joint analysis constrains the maximum amplitude of dynamic subsidence to be 300 m with a range of 0 500 m significantly less than predicted actively spreading marginal basins have no resolvable dynamic subsidence but after removing the effects of crustal thickness variation a few inactive marginal basins are consistently 200 500 m deeper than normal adjacent continental sedimentary basins record a possible dynamic subsidence of 0 500 m although wavelengths are shorter than expected 102 km there is also disagreement between the predicted and observed distribution of anomalous subsidence as well as inconsistencies in initiation and duration these results suggest that mass excess within the mantle represented by subducted slabs has little discernible effect on surface topography instead subsidence and marine inundations throughout southeast asia are predominantly controlled by lithospheric extension and or by foreland loading the spatial and temporal distribution of anomalous subsidence suggests that it might not be caused by dynamic topography associated with subducting slabs a large discrepancy between predicted and observed dynamic topography could be reconciled by changing the density structure of subducted slabs by supporting mass excess with a marked increase in viscosity at depth or by decoupling slabs from the surface with a very low viscosity layer

geochemical study on a well in the western canada basin relation of the aromatic distribution pattern to maturity of organic matter abstract thirty one rock samples from a western canada basin well have been analysed for aromatics using glass capillary gas chromatography with simultaneous flame ionization and sulfur selective flame photometric detection a uniform aromatic distribution pattern with a marked predominance of di and tricyclic aromatic hydrocarbons was observed throughout a depth interval of 3000 meters comprising cretaceous and jurassic sediments the very high relative abundance of sulfur aromatics at two narrow intervals in the triassic and mississippian is attributed to a major change in facies gradual changes with increasing depth have been observed for a series of compound ratios which had been calculated from the isomers of methyl and dimethylphenanthrene and their parent compounds these changes reflect the increasing thermal maturation of the sedimentary organic matter a methylphenanthrene index mpi has been introduced which exhibited a very good correlation with vitrinite reflectance data the mpi is the first maturity parameter which is based on a series of aromatic hydrocarbons this hydrocarbon internal maturity parameter permits the recognition and definition of maturity levels in extracts which can be compared to the maturity e g vitrinite reflectance of source rocks

holocene tephra horizons at klocka bog west central sweden aspects of reproducibility in subarctic peat deposits this paper presents one of the most extensive holocene tephra records found to date in scandinavia microtephra horizons originating from icelandic eruptions were recorded in two ca 2 m thick peat profiles at klocka bog in west central sweden five of the microtephra horizons were geochemically correlated to the askja 1875 hekla 3 kebister hekla 4 and lairg a tephras respectively radiocarbon based dating of these tephras broadly agree with previously published ages from iceland sweden germany and the british isles the identification of the lairg a tephra demonstrates a more widespread distribution than previously thought extending the usefulness of icelandic holocene tephrochronology further north into west central scandinavia long lasting snow cover and seasonal wind distribution in the lower stratosphere are suggested as factors that may be responsible for fragmentary tephra deposition patterns in peat deposits of subarctic scandinavia less

how preexisting weaknesses control the style of continental breakup continental breakup is a highly variable process differences occur in the relative timing and extent of volcanism uplift and graben formation as well as in the mode and amount of continental extension before breakup we propose a model which reconciles this variability with the previously recognized tendency for breakup to occur along preexisting weak trends continental lithosphere is viewed as a composite material composed of two strong layers one in the upper mantle and one in the middle crust finite element simulation indicates that extensional failure at weaknesses in the mantle causes concentrated extension in the mantle and diffuse extension in the crust this leads to early melt segregation and volcanism margin uplift during the late stages of the extension process and relatively narrow symmetrical extended margins in contrast failure at weaknesses in the crustal strong zone causes focused extension in the crust and diffuse extension in the mantle this produces initial graben formation cooling in the lower crust and upper mantle and broad asymmetrical extended margins volcanism only occurs late in the process failure at laterally offset weaknesses within both strong layers leads to a deformation pattern dominated simple shear thus differences in the prerift configuration of the continental lithosphere can control the overall style of continental breakup

assessing the impact of icelandic volcanism on vegetation systems in the north of ireland in the fifth and sixth millennia bc the lairg tephras comprise two of the three most abundantly represented tephra layers in irish holocene peat sequences the impact of these tephras on the vegetation at two lowland raised bogs in northern ireland is investigated through high resolution pollen percentage and concentration studies the palynological response of mire and dryland taxa to the tephra falls is assessed no significant palynological response to either tephra event is recorded

simulating the impacts of distal volcanic products upon peatlands in northern britain an experimental study on the moss of achnacree scotland the potential impact of prehistoric volcanism on distal areas has been the subject of some discussion in both ecology and archaeology an experimental approach is used here to examine the potential effects of distant volcanism on a peatland environment simulations of different tephra and acidity loading designed to approximately replicate the prehistoric hekla 4 ashfall were monitored over 2 years impacts on the peatland ecosystem were assessed by qualitative observations of plant health and abundance semi quantitative observations of flowering measurements of peat ph humification and testate amoebae community composition plots with higher acid loading showed immediate and lasting impacts on plants although other treated plots were less affected changes in testate amoebae and peat humification were inconsistent both within and between plots the experiment demonstrates the potentially severe effects of high acid loading on peatland plants although some responses remain unclear

estimation of the kinetics of geochemical reactions with geophysical models of sedimentary basins and applications abstract the configurational isomerisation and aromatisation reactions which affect the steroid and triterpenoid hydrocarbons present in most organic rich sedimentary rocks are good indicators of the thermal histories of these rocks the extents to which these reactions have occurred can be assessed by gas chromatography mass spectrometry analysis of the organic extracts of the sediment samples we have assumed the reactions can be described as first order and used the model of sedimentary basin formation by extension of the lithosphere to provide thermal histories for the integration of the relevant arrhenius and rate equations governing the reaction rates the activation energies and frequency factors of the reactions were derived by comparing the reaction extents predicted by the model with geochemical observations from basins northern north sea and pannonian basin formed by lithospheric extension which have not experienced major uplift these values were then used to test the thermal consequences of the lithospheric stretching model for nova scotian continental shelf to calculate the amount of uplift and erosion experienced by lower jurassic sediments in the paris and lower saxony basins and the geographical variation in heat flow in a sedimentary basin formed by lithospheric flexure in the foreland basin of alberta in all cases the figures so calculated appear geologically reasonable and receive support from other independent techniques for their estimation the calculated activation energies of all reactions and the frequency factor for aromatisation are chemically sensible the relative values of the frequency factors for the isomerisation reactions could be expected the more sterically hindered c 20 site in a sterane has a lower frequency factor than that for isomerisation at the less hindered c 22 site in hopanes however both values are very low 0 006 and 0 016 s 1 respectively for the back reactions and imply an entropy change of 282 and 271 j mol 1 c 1 respectively the transition states are therefore much more ordered than the reactants this could be the case if catalysis was important no significant variation in catalytic activity can yet be demonstrated in the rocks investigated here

fifty years of the wilson cycle concept in plate tectonics an overview it is now more than 50 years since tuzo wilson published his paper asking did the atlantic close and then re open this led to the wilson cycle concept in which the repeated opening and closing of ocean basins along old orogenic belts is a key process in the assembly and breakup of supercontinents this implied that the processes of rifting and mountain building somehow pre conditioned and weakened the lithosphere in these regions making them susceptible to strain localization during future deformation episodes here we provide a retrospective look at the development of the concept how it has evolved over the past five decades current thinking and future focus areas the wilson cycle has proved enormously important to the theory and practice of geology and underlies much of what we know about the geological evolution of the earth and its lithosphere the concept will no doubt continue to be developed as we gain more understanding of the physical processes that control mantle convection and plate tectonics and as more data become available from currently less accessible regions

icelandic volcanic ash and the mid holocene scots pine pinus sylvestris pollen decline in northern scotland a volcanic ash layer in peat from northern scotland has been identified and coincides exactly with an abrupt decline in pinus sylvestris l scots pine pollen frequencies this provides an isochrone time equivalent marker horizon with which to investigate the timing of the holocene pine decline furthermore two possible causes of the southward shift of the range of pinus in scotland c 4000 bp are suggested a direct effect of acid pollution by chemicals produced by the eruption of hekla h 4 or a volcanically induced climatic perturbation these possibilities have wider implications for the influence of volcanism on postglacial environmental change

aspects of armageddon an exploration of the role of volcanic eruptions in human history and civilization volcanic eruptions are frequently invoked as the mechanism responsible for changes observed in the archaeological and environmental record this paper argues that the evidence for this assumption is slight and that while there are examples of this they are rare several case studies are discussed which illustrate the complex nature of the relationship between human cultures and volcanic eruptions and it is suggested that volcanic activity frequently acts as a stimulus rather than a brake to cultural development

irish tree rings santorini and volcanic dust veils there has recently been renewed interest in the dating of the violent eruption of the aegean island of santorini in the second millennium bc both by its possible effects on tree ring growth in the united states1 suggesting a date of 1628 1626 bc and by acidity peaks in ice cores from south greenland2 suggesting 1645 bc we now show that oak trees growing on bogs in northern ireland produce significant concentrations of extremely narrow rings within a few periods less than 20 years long and that these periods correspond to the dates suggested by other methods for major volcanic eruptions in particular one of them corresponding to a short period beginning in 1628 bc was probably caused by santorini this date is qualitatively better than those derived from carbon 14 or ice cores because it is based on an absolute tree ring chronology

tuzo wilson and the acceptance of pre mesozoic continental drift tuzo wilson s well known pre 1961 opposition to continental drift stemmed from his early experience as a geologist in the appalachians and the canadian shield which convinced him that orogenesis did not change drastically over geologic time conversely taylor in 1910 and wegener in 1912 hypothesized that continental drift began in cenozoic or mesozoic time between 1949 and 1960 tuzo wilson with adrian scheidegger developed a quasi uniformitarian model of progressive continental accretion around fixed archean nuclei tuzo abruptly jettisoned this model in 1961 when under pressure from paleomagnetic evidence for continental drift and a nascent concept of sea floor spreading he finally entertained the possibility of pre mesozoic as well as younger continental drift he immediately found it a superior fit to appalachian and shield geology while his uniformitarian conviction remained intact tuzo had blinded himself to the evidence for continental drift so long as he confined it to taylor or wegener s conception in continental drift operating continuously over geologic time he found a theory he could eagerly accept

tephrostratigraphical evidence for the timing of pleistocene explosive volcanism at jan mayen wavelength dispersive wds electron microprobe analysis of glass shards recovered from pleistocene sediments at ocean drilling program hole 907a leg 151 has been used to define key pleistocene tephrochronostratigraphical markers for the greenland iceland norwegian gin seas two tephras have particularly distinctive geochemistry making them useful as marker horizons in cores from the iceland plateau and potentially further afield these tephras enable the construction of a sedimentation rate history that indicates reduced sediment deposition in the mid brunhes magnetochron possibly through reduced carbonate preservation no significant geochemical weathering of the iceland plateau tephra sequence has occurred the geochemical signature of a key tephra dated to 577 640 ka can be attributed to the jan mayen rock suite demonstrating unambiguously the explosive potential of jan mayen and its potential to contribute to the north atlantic tephra record copyright 2004 john wiley sons ltd

mapping the lower mantle determination of lateral heterogeneity in p velocity up to degree and order 6 the data from the international seismological centre bulletins for the years 1964 1979 are used to derive a three dimensional model of lateral variations of the p velocity in the lower mantle unlike previous studies in which such perturbations were represented by a blocklike parameterization we seek the solution in the form r k 0k l 0l m 0l k r kalm cos m kblm sin m plm cos some 500 000 travel time residuals for teleseismic distances from 5000 earthquakes are used in an iterative procedure to derive the coefficients a and b the maximum k and l used are 4 and 6 respectively in each iteration in addition to solving for the three dimensional structure we also relocate all the earthquakes perturb the average travel time curve and determine station corrections for over 1000 stations particular attention is given to the problem of weighting the individual observations in order to avoid as much as possible the bias due to the uneven distribution of sources and receivers the resulting model shows a high level of perturbations just below the 670 km discontinuity and just above the core mantle boundary where the maximum perturbations reach 1 1 5 of the average velocity even for this highly smoothed model at a depth of 2000 km the rms perturbations are some 3 to 4 times lower than at either of the two boundaries the model predicts well the large scale pattern of observed travel time residuals for various source regions except for the distinct effects of the subduction zones the most striking large scale three dimensional feature of the model is a ring of high velocities circumscribing the pacific basin within a depth range from 1000 km to the core mantle boundary if the proportionality between perturbations in the velocity and temperature is assumed the derived pattern of anomalies could be consistent with a two boundary layer model of convection in the lower mantle some caution however should be exercised in interpreting the results near the 670 km discontinuity where the resolving power of our data set is limited by the lack of adequate control of the upper mantle structure at the same time a significant global increase in the level of perturbations in the lowermost mantle is established beyond question the results of dziewonski et al 1977 on the correlation between the equivalent geoid and the observed geoid for the angular order numbers 2 and 3 is confirmed but there is no significant correlation for degrees from 4 to 6 these calculations are made for the rigid earth richards and hager this issue show that introduction of finite viscosity can change the sign of a geoid anomaly in addition recent studies of lateral variations in the shear velocity reveal the presence of large scale anomalies in the upper mantle thus while the inferences made here with respect to the origin of the gravest orders of the geopotential field are not conclusive they point the way in which results from seismology can be used to address some of the basic questions of geodynamics

principles of geochemical prospect appraisal our current understanding of the geochemical processes responsible for the creation of commercial accumulations of oil and gas can be reduced to simple rules and equations to allow the petroleum geologist to use geochemistry to estimate before drilling the likely volumes and compositions of oil and gas delivered to the trap in most sedimentary basins oil is expelled from source rocks between 120 and 150 c whereas most gas and gas condensate are released between 150 and 230 c when the initial potential of source rocks exceeds 10kg mt oil expulsion efficiencies are between 60 and 90 expelled oil and gas migrate as petroleum rich phases driven by fluid potential gradients most flow is laterally updip in beds with effective horizontal permeabilities greater than 1 md in lower permeability rocks the petroleum fluids move vertically up or down along the path of least resistance i e the most permeable or thinnest beds separating them from a high permeability lateral carrier bed the residual saturations of petroleum left behind along the migration pathway are of the order of a few percent of the porosity geochemical analysis of source rocks helps determine the yields and compositions of petroleum fluids expelled in the catchment area of a prospect these fluid masses are converted to volumes from knowledge of the phase relations and densities of petroleum fluids evaluation of the total volume of rock through which the petroleum potentially can migrate and the mean porosity of the rocks that constitute the migration pathway allow migration losses to be assessed these losses constrain both the range of migration of petroleum fluids away from the mature source rock and the volumes of petroleum remaining for entrapment in the prospect

an outline tephrochronology for the holocene of the north of ireland geochemically typed thin layers of icelandic holocene tephras form a tephrochronology for the north of ireland tephrochronology construction is based on geochemical linkage with dated historic icelandic eruptions and high precision multisample radiocarbon dating comparison with geochemically typed holocene layers at sites throughout scotland and northern england shows that some layers are widespread throughout much of the northern british isles other layers of known historic date have so far been detected only in ireland

the tephrochronology of iceland and the north atlantic region during the middle and late quaternary a review the tephrochronology of iceland and the north atlantic region is reviewed in order to construct a unified framework for the last 400 kyr bp nearly all of the tephra layers described are also characterised geochemically a number of new tephra layers are analysed for the first time for their geochemical signature and a number of pre holocene tephra layers have been given an informal denotation the tephrostratigraphy of ash zone ii is highlighted where possible the rhyolitic tephra layers found outside iceland have been correlated to known icelandic tephra layers or to the volcanic source area the application of tephra fallout in various depositional environments is described and discussed copyright 2000 john wiley sons ltd

icelandic volcanic ash and the mid holocene scots pine pinus sylvestris decline in the north of ireland no correlation tephra linked pollen and dendrochronological studies were performed on mid holocene subfossil peats and pines and two lowland raised bogs in the north of ireland the results demonstrated that at these sites contrary to recent findings in the north of scotland there was no temporal link between the decline in pine pollen and tephra from the eruption of the icelandic volcano hekla h4

probing the structure of the deep continental crust old buried deformed crystalline rocks apparently make up most of the 40 kilometer thick continental crust this part of the earth is poorly explored and constitutes a major frontier of modern earth science two techniques seismic reflection profiling and drilling which were developed by industry for other purposes offer special potential for such exploration seismic profiling of the deep crust by cocorp the consortium for continental reflection profiling has already produced important information including evidence for extensive thin skinned thrusting of older rocks over a continental margin as the corresponding ocean basin closed deep drilling of crystalline rocks of the continents for scientific purposes is so far relatively unexploited in the united states but is already being carried on elsewhere in general big science is likely to become more important in basic geology as this frontier is explored

late quaternary icelandic tephras in ireland and great britain detection characterization and usefulness microscopic studies of late quaternary tephras from iceland yield a detailed tephrochronology in deposits of the british isles where the quantities of volcanic glass employed are much less than those used to construct almost any other late quatemary tephrochronology we summarize improved methods of isolating extremely sparse glass shards for light microscope and electron microprobe analysis and provide major element geochemistry for 20 volcanic glass layers detected in ireland including those which comprise an outline historic tephrochronology for ireland the paper highlights possible limitations of chronology construction when attempting to separate dated tephras whose major element geochemistries are almost identical tephras in other parts of the british isles and europe are used with those in ireland to demonstrate further applications of tephrochronology especially for dating deposits where other dating methods e g radiocarbon have proved difficult

subsidence in intracontinental basins due to dynamic topography the origin of anomalous tectonic subsidence ats of large intracontinental basins long after their most recent phase of extension and last thermal perturbation is the subject of a long standing debate we show that deep earth processes may contribute to the subsidence of these tectonically stable basins by analysing the tertiary mantle convection driven topography history of a global set of more than 220 intracontinental basins integrated into a plate kinematic framework most basins are affected by increasing negative dynamic topography over the last 70 myr due to the motion of many continents away from large mantle upwellings and towards downwellings previously located along the perimeter of the supercontinent pangaea during continental dispersal increasing negative dynamic topography causes dynamic subsidence of the basins creating additional accommodation space we utilise a parameter from a global crustal analysis of intraplate basins termed anomalous tectonic subsidence to quantify sediment accumulation not related to crustal stretching we propose that dynamic subsidence due to plate motions relative to the underlying mantle as well as variations in the large scale convection patterns can significantly contribute to the creation and destruction of accommodation space in intraplate basins