uncertainties in the relative positions of the australia antarctica lord howe and pacific plates since the late cretaceous we determined parameters that describe finite rotations and their uncertainty regions for relative plate motion at the spreading centers between the pacific and antarctica plates between australia and antarctica and between the lord howe rise and australia we combined these to yield a range of possible finite rotations describing the relative positions of the pacific australia antarctica and lord howe plates since the late cretaceous if the pacific australia plate boundary has had its present trend since anomaly 18 time reconstructions show 330 110 km of motion of the pacific plate relative to the lord howe rise since anomaly 5 time 9 8 m y 420 110 km since anomaly 6 time 19 5 m y 770 330 km since anomaly 13 time 35 6 m y and 820 260 km since anomaly 18 time 43 0 m y we examined two cases for times prior to anomaly 18 assuming a late cretaceous age of australia antarctica separation if a plate boundary existed between the lord howe rise and pacific plates since the late cretaceous with no plate boundary in antarctica reconstructions with the lord howe rise fixed predict 610 200 km of westward motion of the pacific plate between the times of anomalies 31 and 22 followed by 260 100 km of northward motion between the times of anomalies 22 and 18 if the lord howe rise was fixed to the pacific plate until the eocene but a plate boundary existed between east and west antarctica reconstructions show very little motion across this boundary between the times of anomalies 31 and 22 followed by convergence between the times of anomalies 22 and 18 this second case also brings 70 80 m y paleomagnetic poles from the pacific and east antarctica plates into better agreement than the first case but large uncertainties in the reconstructions do not allow the first case to be conclusively eliminated

late mesozoic and cenozoic palaeomagnetism of australia i a redetermined apparent polar wander path summary palaeomagnetic measurements have been carried out on one cretaceous and five cenozoic sedimentary sequences of australia of those one is in the carnarvon basin of north western australia and the others are in the otway basin of south eastern australia the new results are used together with those published previously to define a revised late mesozoic cenozoic apparent polar wander path for australia this path differs from earlier basalt derived paths by the absence of a large westward excursion and zig zag irregularities it is characterized instead by a substantially straight cenozoic trajectory a sharp bend in the late cretaceous and a non uniform rate of apparent polar wander the early tertiary segment of the new path lies north of the original paths thus eliminating a discrepancy that has been noted previously between the indian and australian palaeomagnetic data luyendyk rennick peirce and klootwyk peirce a re examination of the original data suggests that this discrepancy as well as two others in the australian results may have been caused principally by incomplete time averaging of remanence directions because the volcanics on which the results were based had been extruded episodically

comments on a weighted least squares fit of the australian apparent polar wander path for the last 100 myr by r j musgrave with the recent publication of musgrave s paper musgrave 1989 two late mesozoic cainozoic pole paths that differ substantially in age calibration have become available for australia the earlier path path 1 is age calibrated almost entirely by remanence directions of sedimentary sequences idnurm 1985 the new path path 2 is calibrated by the remanence directions of volcanics path 2 has the special merit that again it puts to use data which fell out of favour in the late 1970s and early 1980s because of serious discrepancies with the indian data base e g embleton 1981 embleton mcelhinny 1982 the two approaches to australia s late mesozoiccainozoic apwp differ fundamentally in the treatment of scatter in pole data the approach adopted for path 1 attempts to eliminate abnormally large scatters at the source believed to be the incomplete averaging out of geomagnetic secular variations for discussion see idnurm 1985tby utilizing the time averaging characteristics of sedimentary sequences the approach for path 2 relies heavily on statistics to eliminate the scatter the differences between the paths are of concern especially when they are used for age dating of weathered profiles the age estimates may differ by up to about 15ma in the tertiary corresponding to an angular difference of so and musgrave has attempted to test the paths by comparing their respective age estimates on such units with independent geological constraints the results are in favour of path 2 but he appears to have made some errors in these comparisons errors that invalidate the finding more seriously the method devised for age calibration of path 2 seems unsound the first error occurs when the palaeomagnetic age estimates for a new caledonian laterite are compared with stratigraphic evidence that its age is early miocene or older musgrave finds that this stratigraphic age limit is consistent with path 2 but not consistent with path 1 and concludes that the test has provided a clear discrimination in favour of the new apwp this is not correct fig 1 shows path 1 with the new caledonian pole aa since the 95 per cent confidence circle for aa encloses the 26 ma calibration pole path 1 is consistent with an early miocene age for the laterite as a separate issue all three new caledonian laterite poles in musgrave s paper have values of a that are excessively high for such material see for example his table 1 suggesting unresolved complexities in their remanence

effects of latent heat release at phase boundaries on flow in the earth s mantle phase boundary topography and dynamic topography at the earth s surface abstract mantle flow models that do not consider the effects of latent heat on phase boundaries typically predict dynamic surface topography too large to be compatible with observations here these effects were implemented in a mantle flow model and resulting changes in dynamic topography and topography of phase boundaries were computed inclusion of these effects was found to reduce the rms amplitude of dynamic topography by about 50 60 m still leaving a substantial misfit from observations in most cases considered generally it also leads to a slight improvement of correlation with dynamic surface and phase boundary topography constrained by observations results thus indicate that the model implemented here is applicable to the earth but that other effects need to be considered as well in order to fully explain phase boundary and dynamic surface topographies

role of crustal stretching on subsidence of the continental crust abstract the principal areas of subsidence of the continental crust are wide intracontinental basins and passive continental margins in many intracontinental basins crustal extension amounts to only a few percent and is unable to explain their subsidence as shown for the timan pechora pre caspian and west texas basins the deep black sea and south caspian basins are underlain by highly attenuated continental crust having velocities in the 7 km s range that shows no evidence for significant extension in passive margins upper crustal extension ranges between 10 and 40 whereas the lower crust is attenuated by 2 3 times e g campos basin north biscay margin large discrepancy between upper crustal stretching and lower crustal attenuation is seen in the crustal configuration of many intracontinental grabens e g baikal and dniepr prypyat basins only in highly extended areas such as the basin and range province and the east china rift system does crustal stretching account for the observed crustal thinning the observed discrepancy between upper extension and crustal thinning across intracontinental rifts and passive margins and particularly in some wide intracontinental basins suggests that crustal stretching alone cannot account for the subsidence of these basins phase transformations in the lower crust probably facilitated by the presence of hydrous fluids can cause rapid 1 ma as well as long term 200 1500 ma upward displacement of the moho discontinuity resulting in high amplitude subsidence of the crust in areas of crustal extension this mechanism can overprint subsidence induced by thermal relaxation of the lithosphere the case of the black sea and south caspian basins shows that density increase of the lithosphere can also occur independently of crustal stretching

long term sea level fluctuations driven by ocean basin dynamics earth9s long term sea level history is characterized by widespread continental flooding in the cretaceous period 145 to 65 million years ago followed by gradual regression of inland seas however published estimates of the late cretaceous sea level high differ by half an order of magnitude from 40 to 250 meters above the present level the low estimate is based on the stratigraphy of the new jersey margin by assimilating marine geophysical data into reconstructions of ancient ocean basins we model a late cretaceous sea level that is 170 85 to 270 meters higher than it is today we use a mantle convection model to suggest that new jersey subsided by 105 to 180 meters in the past 70 million years because of north america9s westward passage over the subducted farallon plate this mechanism reconciles new jersey margin based sea level estimates with ocean basin reconstructions

the case for dynamic subsidence of the u s east coast since the eocene the dynamic subsidence of the united states east coast is addressed using the discrepancy between regional and global estimates of sea level elevation of paleoshorelines and adjoint models of mantle convection that assimilate plate motions and seismic tomography the positions of eocene and miocene paleoshorelines are lower than predicted by global sea levels suggesting at least 50 m and possibly as much as 200 m of subsidence since the end of the eocene dynamic models predict subsidence of the east coast since the end of eocene although the exact magnitude is uncertain this subsidence has been occurring during an overall global sea level fall with the eustatic change being larger than the dynamic subsidence this results in a regional sea level fall in the absence of land subsidence dynamic subsidence is consistent with the difference between eustasy and regional sea level at the new jersey coastal plain

marine magnetic anomalies palaeomagnetism and the drift history of gondwanaland abstract the results of palaeomagnetic surveys of mesozoic and tertiary rocks from gondwanaland can be reconciled with the results of modelling the evolution of oceanic floors from analyses of marine magnetic anomalies previous inconsistencies were mainly due to errors apparent in the australian cenozoic palaeomagnetic data an alternative tertiary apparent polar wander path apwp has been constructed from an analysis of all published laterite and weathered profile data palaeomagnetic results for africa antarctica australia india madagascar and south america are compared for rotations corresponding to marine magnetic anomalies 16 22 28 34 and m1 and for fit india has been selected as the reference continent since it provides the most detailed apwp having drifted about 50 of latitude since breakup

cenozoic subsidence and uplift of continents from time varying dynamic topography time varying global dynamic topography has been computed for the entire cenozoic the spherical viscous flow model is driven by a distribution of density heterogeneity based on mesozoic and cenozoic subduction by using the calculated topography the uplift and subsidence histories of five regions fixed to the north american indian australian indonesian and south american continents are computed predicted vertical motions are in qualitative agreement with observed values except for india and south america for australia and north america the predicted periods of uplift and subsidence are out of phase with respect to observations but display the correct overall trend the latest phase of uplift for north america is directly related to the cessation of kula plate subduction after 48 ma dynamic topography depends on the viscosity structure of the mantle a lower mantle that is 50 times more viscous than the upper mantle yields the best agreement between modeled and predicted vertical motions the presence of a low viscosity channel beneath the lithosphere has only a small influence on our results compared to dynamic topography the time varying geoid is insignificant in controlling relative sea level

total tectonic subsidence a parameter for distinguishing crust type at the u s atlantic continental margin total tectonic subsidence tts is the difference between the prerifting continental crust elevation and the present sediment unloaded basement depth in a sedimentary basin tts is calculated using observations of bathymetry and basement depth and assumptions about sediment density and the loading response of the lithosphere i use the extensional model for sedimentary basin formation to interpret the tts of a passive continental margin that model predicts that the tts on an old margin should define the major crust type boundaries and indicate the lateral distribution of extension within the extended continental crust tts analysis of the u s atlantic continental margin indicates that the boundary between extended continental and oceanic crusts lies along the east coast magnetic anomaly ecma to the north of the blake spur fracture zone bsfz and along the blake escarpment to the south there is no tts anomaly associated with the blake spur magnetic anomaly which seems to be underlain by normal oceanic crust the ecma appears to be associated with a tts minimum but i attribute that to artificially shallow estimates of depth to magnetic basement under the ecma tts estimates of extended continental crust thickness agree well with gravity models except where the problem with magnetic basement depth estimates interferes the amount of crust extension prior to seafloor spreading varies along the strike of the margin the most abrupt change is at the bsfz across the bsfz the amount of extension varies by 160 km but the volume of continental material does not vary the extension variation may be caused by lateral changes in the gross rheology of the continental lithosphere in the case of the bsfz it would be the suture of more ductile pre late paleozoic african craton with more brittle north american craton that could cause the abrupt change

generation of long wavelength heterogeneity in the mantle by the dynamic interaction between plates and convection lateral variations in seismic velocity through its dependence on temperature can easily be generated at the gravest harmonics including degrees one and two by the dynamic interaction between plates and convection models of thermal convection with a single non subducting plate have been formulated in a cylindrical geometry plates of width one to four times times the thickness of the convecting region strongly modulate the flow by being pushed over cold downwellings and inhibiting cooling of the fluid beneath during rapid motion off of hot regions a large scale pattern of shear is developed causing small uprising limbs to be swept into the largest upwellings both insulation and plume plume collisions pump energy into the lower wavenumber harmonics

late mesozoic and cenozoic palaeomagnetism of australia ii implications for geomagnetism and true polar wander summary new palaeomagnetic results from australia indicate that throughout the cenozoic era the continent lay further south than suggested by hot spot data moreover while hot spots give a uniform rate of drift during most of the cenozoic the drift rate obtained from apparent polar wander varies considerably the discrepancies between the palaeomagnetic and hot spot results are analysed by comparing the australian data with those of europe and the central pacific the analysis suggests that the discrepancies are due to 1 departures of the earth s magnetic field from the geocentric axial dipole model and 2 either true polar wander or a non axial inclined dipole component it is found that since the mid tertiary the dominant non dipole component has been a quadrupole and that during this period both the quadrupolar field and the true polar displacement non axial dipole component decreased progressively during the quaternary and also at the earliest tertiary the non dipole components appear to have been moderate or small the comparison of data sets demonstrates that considerable errors may be incurred when cenozoic and presumably earlier poles from one geographic region are used to derive those of another widely separated region the results also imply that absolute plate velocities estimated from palaeomagnetic data can contain substantial errors and that hot spot data may need significant adjustments for true polar wander to yield correct palaeolatitudes finally the new early tertiary pole for australia is used in conjunction with updated early tertiary poles from other lithospheric plates to reapply the mckenzie test for true polar wander the results indicate a small true polar displacement since the beginning of the tertiary the amount and direction of the displacement however differ from those generally obtained from hot spot data

evolution of the west siberian basin the west siberian basin is one of the largest intracratonic basins of the world and an important hydrocarbon province of russia perhaps the most important geologic event in siberia was the emplacement of basalts around 250 ma i e permo triassic boundary covering an area of about 5 10 6 km 2 this volcanism may be responsible for a mass extinction that occurred around permian triassic time the prebasaltic rifting event was limited to the north northeastern sector of the basin initial basin wide subsidence took place in the jurassic as a result of which the western part of siberia became the west siberian basin bounded by uplifts to the east and to the west one of the surprising aspects of the west siberian basin is the abundance of subvertical faults believed to be result of strike slip movement while intraplate inversions and fault reactivation structures have been observed in many cratons subvertical faults observed in the west siberian basin are unique because of their geometries and abundance the differentiation between the effects of tectonics and eustasy in cratonic basins is simple the global eustatic signal is basin wide with regional and local tectonics playing an overprinting role thus the middle jurassic turonian first second and third order cycles in the west siberian basin were primarily driven by eustasy the middle jurassic turonian series can be subdivided into two second order and 16 third order transgressive regressive cycles within dataset extent fourth order cycles appear to be controlled by delta shifting although extensively studied a number of fundamental questions regarding the origin and evolution of the west siberian basin remain unresolved or poorly documented in the literature

paleomagnetic results from the waipapa terrane northland peninsula north island new zealand tectonic implications from widespread remagnetizations paleomagnetic samples were collected from a wide variety of rock types of the waipapa terrane which is exposed along the eastern coast of the northland peninsula twelve sites yield stable magnetic directions which fail both a fold and regional attitude test at the 99 confidence level and indicate that widespread remagnetization has occurred over a large 200 km area rock magnetic experiments suggest that the mechanism for remagnetization was through the formation of fine grained magnetite and hematite and was probably controlled by local variation in fluid migration the mean in situ direction for the 12 sites is i 70 2 d 14 4 95 7 1 kappa 38 6 which is significantly different from the predicted axial dipole field directions at the 95 confidence level the age of the remagnetization is unclear in an effort to date the remagnetization a synthetic apparent polar wander apw path was constructed for new zealand using australian data and the apparent south pole from the remagnetized waipapa sites latitude 69 7 s longitude 150 7 e 95 11 2 was compared to this apw path using this method the age of the remagnetization is constrained to be between 12 and 58 ma a major change in the tectonic regime occurred at 25 ma which is evidenced by obduction of the northland allochthon and initiation of arc volcanism and subduction fluid migration and or elevated temperatures driven by the initiation of subduction and arc volcanism along with the obduction of the northland allochthon seem likely mechanisms for the remagnetization

revised history of early tertiary plate motion in the south west pacific reanalysis of early tertiary magnetic anomalies on the pacific plate south of the campbell plateau indicates that in early tertiary time there was a previously unrecognized triple junction of the pacific the antarctic and a third plate now beneath the bellingshausen sea corresponding revised parameters for pacific antarctica motion do not require early tertiary displacements within antarctica or new zealand but suggest a change in direction of the pacific plate over the hotspots of approximately the same sense and timing as the hawaiian emperor bend

pre mesozoic geodynamics of the precaspian basin kazakhstan abstract this paper concentrates on the pre mesozoic history of the precaspian basin representing more than half of the 20 km of its sedimentary thickness we present the evolution of sediments deposited in the basin through time by several regional sections of the basin these image from the devonian the creation and evolution of a deep intercontinental basin which existed from carboniferous to permian palinspastic reconstructions show also the evolution of the basin s margins their relations with the southern pre uralian foredeep in the east and carbonate build ups in the southeast we present a reconstruction for the early history of the precaspian basin which became an individual basin only at the end of the permian as a result of the uralian orogeny the basement of the central precaspian depression is characterised by a thin crust where a low velocity layer is absent a layer of abnormally high velocities exists below the crust which on the basis of structural and gravitational field data is interpreted as eclogite we put forward a scenario for the age and emplacement of eclogite lenses at the base of the crust they are possibly implemented in the hangingwall from a westward subduction zone existing during the vendian before the collision giving birth to the proto urals most of the basin subsidence is due to the thinning mainly during devonian and increase of the average density of the crust present crustal density has characteristics of intermediate to lower crust interpreted by some authors as oceanic we propose that the loading effect of the eclogites emplacement may explain also a part of the precaspian basin subsidence

a weighted least squares fit of the australian apparent polar wander path for the last 100 myr summary recent versions of the australian apparent polar wander path apwp for the late mesozoic and tertiary show considerable variation re examination of the australian igneous data suggests that they are more reliable than assumed by some recent authors the trajectory of the australian apwp is defined by fitting the position of a set of poles including both igneous and laterite overprint data this allows the dated igneous poles to be used to determine age as a function of distance along the trajectory both the trajectory and the age are fitted by means of weighted least squares regression and are given approximate confidence limits age is best fitted in the australian case as a linear function of distance along the apwp this result contrasts with that of idnurm who suggested a variable rate of polar wander during the tertiary the new apwp is in better agreement with hot spot data dating of new caledonian laterites by the new apwp gives a result consistent with geological evidence while dating by reference to idnurm s path does not large non dipole components or significant true polar wander are not needed to explain the australian tertiary apwp

linearity spectrum analysis of multi component magnetizations and its application to some igneous rocks from south eastern australia summary a method that enables the objective resolution of almost parallel multi component magnetizations is described and demonstrated a feature distinguishing this method from others is its simultaneous analysis of demagnetization data from a group of specimens rather than the analysis of data from one specimen at a time the only prerequisite is that the specimens are derived from a homogeneous source thus for a formation carrying a simple single component magnetization all specimens from the formation may be simultaneously reduced for a more complicated two component magnetization it is shown that only specimens from a particular site can be considered homogeneous and for a complex three component system each sample often requires undivided attention thus the workload is proportionally increased to achieve analyses of comparable reliability from data of variable quality new pole positions from mesozoic intrusions of the sydney basin nsw are from the marsden park breccia pipe 48 s 127 e a95 6 the st marys breccia pipe 46 s 150 e a95 8 the prospect dolerite 60 s 142 e a95 13 and 53 s 180 e a95 6 and from the dundas breccia pipe 58 s 162 e a95 36 and 31 s 195 e a95 16 the last two formations possess multi component magnetizations these pole positions are consistent with previous results from south eastern australia

aulacogens and aulacogeosynclines regularities in setting and evolution abstract aulacogens and aulacogeosynclinal zones represent intra continental palaeorifts and inverted palaeorifts they were formed in the process of the break up of continents during the late proterozoic inversion of such basins occurred variably during the baikalian caledonian hercynian and alpine orogenic cycles in response to the build up of intraplate compressional stresses emanating from orogenic belts aulacogens were first recognized on the stable russian platform where they correspond to linear graben type depressions filled with proterozoic sediments often buried beneath a thick cover of palaeozoic and younger sediments some aulacogens have experienced a short period of reactivation during the palaeozoic aulacogeosynclines differ from the genetically related aulacogens by their greater dimensions and the amount of lithospheric extension that can go to the extent of opening of small ocean basins consequently they are characterized by a greater degree of destruction of the continental crust the depth of subsidence and the complexity of their post rift development which commonly terminates with their compressional deformation giving rise to the development of intracontinental linear folded and thrusted structures frequently associated with low grade metamorphism and small intrusions many ancient platforms are characterized by aulacogens metaplatforms are dissected by aulacogens and aulacogeosynclines whereas geosynclinal troughs are the precursors of geosynclinal mobil belts aulacogens aulacogeosynclines and geosynclinal troughs represent a group of negative linear structures which are characterized by an increasing degree of crustal destruction during rifting processes and increasing mobility during lithospheric contraction

evidence for late eocene emplacement of the malaita terrane solomon islands implications for an even larger ontong java nui oceanic plateau 1 most tectonic models for the solomon islands arc invoke a miocene collision with the ontong java plateau ojp to halt cessation of pacific plate subduction initiate australian plate subduction and emplace the malaita terrane which shares the characteristic basement age and geochemistry of ojp existing paleomagnetic evidence however required the malaita terrane to have been fixed to the arc from at least the late eocene new sampling has yielded a paleomagnetic pole from aptian albian limestones and mudstones that falls between the apparent polar wander paths for the australian plate and ojp confirming the extended period of residence of the malaita terrane on the arc arc derived turbidities within late eocene through miocene limestones on malaita and santa isabel and related clasts in broadly contemporary sandstones and conglomerates on santa isabel also attest to early emplacement modeling the emplacement at 35 ma satisfies both the paleomagnetic data and the sediment provenance continuing the reconstruction to 125 ma leaves the malaita terrane far from ojp at the time of plateau formation ojp is now understood to have formed as part of a larger ontong java nui also comprising the hikurangi and manihiki plateaus separated by spreading during the cretaceous restoring the separation of the known elements and invoking an additional triple junction unites the now largely subducted malaita terrane with the rest of ontong java nui subduction of substantial areas of the ontong java nui plateau with little geological signal other than a reduction in arc volcanism is a corollary

phanerozoic marine inundation of continents driven by dynamic topography above subducting slabs a spherical model of mantle flow constrained by the locations of trenches can be used to predict the dynamic topography of the earth s surface and hence the marine inundation of continents for past periods of high sea level the predicted geographical pattern of flooding correlates well with the geological record the high spatial correlation may result from increased plate velocities at these times leading to increased rates of subduction subsidence and inundation at convergent margins

apparent polar wander paths for the major continents 200 ma to the present day a palaeomagnetic reference frame for global plate tectonic reconstructions summary synthetic apparent polar wander apw paths for north america south america eurasia india central africa australia and antarctica for the last 200 myr are proposed computation of these apw paths is based upon the latest version 4 5a of the global paleomagnetic database gpmdb a revised global plate tectonic model since the early jurassic and a new technique for generating smoothed apw paths the smoothing technique includes the following steps 1 pre selection of palaeopoles including pre filtering parameters number of sites number of samples per site 95 per cent confidence circle about mean direction cleaning procedure and time uncertainty 2 generation of palaeolatitude and declination plots for a reference site on each continent that combines palaeopoles via a global plate tectonic circuit 3 independent spline regression analyses of the palaeolatitude and declination plots 4 removal of palaeolatitude or declination data that deviate by more than 10 from the regression curves post filtering process 5 generation of synthetic apw paths from the resulting palaeolatitude and declination plots these synthetic apw paths are then rotated into african coordinates to determine the best fit apw path and a global palaeomagnetic reference frame four representative plate tectonic reconstructions and global plate velocity fields are presented for the three time intervals that correspond to globally synchronous changes in plate motion

southern ocean nitrogen and silicon dynamics during the last deglaciation abstract the reinvigoration of overturning in the southern ocean is hypothesized to have returned co2 from the deep ocean to the atmosphere at the end of the last ice age large peaks in opal accumulation have been put forward as evidence for an increase in wind driven upwelling between 10 and 15 ka here we use coupled nitrogen and silicon isotope records alongside opal accumulation rates to provide quasi quantitative estimates of southern ocean nutrient supply by upwelling and nutrient utilization across this interval significant changes in the consumption of n and si across the two opal accumulation peaks indicate major changes in both upwelling and nutrient demand we find n and si consumption to be relatively incomplete during peak opal accumulation at the onset of the deglaciation this indicates that nutrient supply was significantly enhanced the second deglacial peak in opal accumulation is associated with more complete si consumption and variable n consumption we suggest that this peak represents strong upwelling and more complete utilization of the available silicic acid pool differences between the si and n responses during opal peaks may stem from decreasing iron availability across the glacial termination the nutrient isotope evidence for excess nutrients during the deglaciation indicates that the high export productivity was insufficient to overcome the evasion of co2 to the atmosphere as a result of physical circulation changes previous work has demonstrated that the reinvigoration of overturning circulation during the deglaciation causes a transient peak in nutrient supply to the low latitudes this is supported by our data which indicate that relatively high macronutrient concentrations were maintained in the southern ocean surface waters that are incorporated into mode waters despite high demand

plate tectonic evolution of the southern margin of eurasia in the mesozoic and cenozoic abstract thirteen time interval maps were constructed which depict the triassic to neogene plate tectonic configuration paleogeography and general lithofacies of the southern margin of eurasia the aim of this paper is to provide an outline of the geodynamic evolution and position of the major tectonic elements of the area within a global framework the hercynian orogeny was completed by the collision of gondwana and laurussia whereas the tethys ocean formed the embayment between the eurasian and gondwanian branches of pangea during late triassic early jurassic times several microplates were sutured to the eurasian margin closing the paleotethys ocean a jurassic cretaceous north dipping subduction boundary was developed along this new continental margin south of the pontides transcaucasus and iranian plates the subduction zone trench pulling effect caused rifting creating the back arc basin of the greater caucasus proto south caspian sea which achieved its maximum width during the late cretaceous in the western tethys separation of eurasia from gondwana resulted in the formation of the ligurian penninic pieniny magura ocean alpine tethys as an extension of middle atlantic system and a part of the pangean breakup tectonic system during late jurassic early cretaceous times the outer carpathian rift developed the opening of the western black sea occurred by rifting and drifting of the western central pontides away from the moesian and scythian platforms of eurasia during the early cretaceous cenomanian the latest cretaceous paleogene was the time of the closure of the ligurian pieniny ocean adria alcapa terranes continued their northward movement during eocene early miocene times their oblique collision with the north european plate led to the development of the accretionary wedge of the outer carpathians and its foreland basin the formation of the west carpathian thrusts was completed by the miocene the thrust front was still propagating eastwards in the eastern carpathians during the late cretaceous the lesser caucasus sanandaj sirjan and makran plates were sutured to the iranian afghanistan plates in the caucasus caspian sea area a north dipping subduction zone jumped during paleogene to the scythian turan platform the shatski terrane moved northward closing the greater caucasus basin and opening the eastern black sea the south caspian underwent reorganization during oligocene neogene times the southwestern part of the south caspian basin was reopened while the northwestern part was gradually reduced in size the collision of india and the lut plate with eurasia caused the deformation of central asia and created a system of nw se wrench faults the remnants of jurassic cretaceous back arc systems oceanic and attenuated crust as well as tertiary oceanic and attenuated crust were locked between adjacent continental plates and orogenic systems

new late eocene pole for australia time averaging of remanence directions and palaeogeographic reference systems summary a new late eocene 36 5 ma south palaeomagnetic pole based on 33 sampling levels in the browns creek formation of the otway basin south eastern australia lies at 65 5 s 112 5 e with ag5 2 5 this pole fills a 30 myr gap in the palaeogene part of the australian apparent polar wander pole path and appears well suited for calibrating the path because of a well defined age and evidence that the sequence was magnetized during a depositional period long enough to thoroughly average out secular variations the remanence seems to have been acquired during postdepositional re working of the sediment the pole agrees with one biostratigraphically dated and three undated poles that constrain the palaeogene trajectory all palaeogene poles on the path lie west of an alternative apparent polar wander path the latter is modelled by low order curve fitting of much more widely scattered poles from basalts in which the scatter appears to be due to incomplete time averaging of remanence directions the new pole also reinforces a previously observed systematic westward displacement by a few degrees of the early tertiary palaeomagnetic poles relative to hotspot derived poles this displacement may be caused by true polar wander and or departures from the geocentric axial dipole model it again highlights the approximateness of the available palaeogeographic reference systems

hotspots in the southern oceans an absolute frame of reference for motion of the gondwana continents abstract the geometry and geochronology of aseismic ridges and oceanic islands in the southern oceans provide a good test of the proposition that hotspots remain fixed over long periods of time that is motion of an order of magnitude less than the relative motion between plate pairs in most cases it is concluded that inter hotspot movement cannot be discerned for the period 100 m y to present and that widely distributed hotspots in the atlantic and indian oceans provide a frame of reference for plate motions following the disintegration of gondwanaland which is independent of paleomagnetism this frame of reference is absolute in that it gives the motion of the lithosphere with respect to the mantle hotspots the absolute motion model indicates that africa and antarctica are now moving only very slowly that there has been significant relative movement between east and west antarctica since the cretaceous and prescribes the relative motion between the somali and african plates

rifting and lower crustal reflectivity a case study of the intracratonic dniepr donets rift zone ukraine 1 intracratonic rifting caused by late devonian extensional stresses in the east european craton created the largest rift zone in europe the pripyat dniepr donets rift southeast ukraine the rift basin is approximately 2000 km long up to 170 km wide and 22 km deep wide angle refraction and reflection seismic data from the donbas basin deep seismic refraction and reflection experiments dobre 99 project together with gravity and magnetic data are analyzed for the structure and evolution of the donbas fold belt which is the uplifted and deformed part of the dniepr donets basin the seismic data are used for identification of large scale crustal structures and modeling of the seismic velocities of the crust and uppermost mantle a ray trace based velocity and density model is derived by joint inversion of gravity and traveltime data the inversion result reveals a zone of high density and velocity beneath the basin at middle to lower crustal levels slightly offset to the ne of the rift axis full waveform synthetic seismograms matching the observed data show high amplitude and low frequency arrivals from this high density body as well as from the moho we interpret the high amplitude low frequency signals as reflections from layered magmatic rocks which intruded into the ductile lower crust during the main rift phase and subsequently were sorted by fractional crystallization the intrusive material thickened the lower crust by approximately 50 this may explain the enigmatic flat moho topography across the rift zone which has been significantly stretched 1 3 the rifting initiated in the late devonian frasnien as a consequence of back arc extension in relation to subduction of the paleo tethys ocean the subducting oceanic slab may have enriched the mantle with volatiles and created convection leading to strong partial melting upwelling and continued rifting in the famennien we interpret the asymmetrical rift geometry as a combination of pure and simple shear tectonic processes

the geodynamic evolution of the precaspian basin kazakhstan along a north south section abstract several hypotheses exist for the origin and evolution of the precaspian basin there are more than 20 km of sediments deposited yet there is little consensus on the causes of the subsidence except for the presence of a thick salt layer lower permian the main problem is the chronostratigraphic interpretation of the sediments in the centre of the basin where the calibration of seismic data with well data from the basin margins is problematic at deep levels the age of the deepest sediments could be either riphean or devonian a generalised cross section of the precaspian basin roughly perpendicular to the central elongated e w depocentre is used to represent the basin s evolution several evolutionary steps from the end of the riphean until the present are demonstrated tectonic subsidence analysis indicates that there are six main phases of evolution 1 subsidence during an active rifting phase in riphean times 2 rifting during the vendian ordovician poorly dated 3 significant subsidence during the late devonian in an extensional context possibly due to back arc rifting 4 acceleration of subsidence during the late carboniferous permian synchronous with or just following the closure of the uralian ocean a major subsidence phase in the dniepr donets basin and possible subduction to the south of the basin 5 renewed rifting during the triassic coincident with a general phase of extension in eurasia and the opening of the neo tethys and 6 neotectonic subsidence resulting from crustal down bending in a generally compressional setting the nature of the crust underlying the basin is not well known it could be riphean early palaeozoic or devonian oceanic crust or continental crust attenuated during the several episodes of supposed rifting between the riphean and the triassic estimations of crustal thickness in the basin vary and they depend on the interpretation of a high velocity layer situated at the base of the crust the presence and general distribution of this layer is confirmed by gravity data it may be considered as the uppermost mantle as oceanic crust metamorphosed into eclogite at depth during collision and then exhumed and emplaced at the base of the crust or as lower crust transformed in situ into eclogites the crustal thinning factor leading to the observed present crustal thickness assuming an initial thickness of 40 km is 3 3 in the two first cases and 2 in the latter if the crust is considered to be continental the geophysical and subsidence data are discussed in terms of basin forming mechanisms such as 1 intracontinental rifting of early palaeozoic devonian or permo triassic ages 2 oceanisation of continental crust during riphean or devonian time 3 eclogititisation at the base of the crust in the upper mantle or by metamorphism of subducted oceanic crust and 4 down bending due to compressional forces or mantle flow induced by subduction collision processes in carboniferous and recent times

a correction for sediment load upon the ocean floor uniform versus varying sediment density estimations implications for isostatic correction abstract the isostatic correction for the sediment load on oceanic basement has often been calculated using a uniform sediment density irrespective of either water depth or total sediment thickness an alternative method is proposed here in which the sediment density is calculated using the density depth equations of hamilton 1976 for calcareous clay and terrigenous sediment sequences this alternative method takes into account the water depth and total sediment thickness when estimating the sediment density for example deep water 4000 m sediment sequences are likely to be clay rich thick sediment sequences 2000 m usually have a high terrigenous component and shallow sequences are likely to be calcareous rich sediment thicknesses in excess of 1500 m are generally close to a continental margin these density estimations are compared with measurements from 9 ocean drilling program drill sites 1 deep sea drilling project drill site and from densities derived from seismic interval velocities the most commonly used estimates of uniform sediment density were used to calculate isostatic corrections for a 12 km thick sediment sequence these results were then compared with the results determined using the proposed alternative method of estimating sediment densities the proposed method produces isostatic corrections similar to those derived by published methods for sediment sequences

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

age spreading rates and spreading asymmetry of the world s ocean crust we present four companion digital models of the age age uncertainty spreading rates and spreading asymmetries of the world s ocean basins as geographic and mercator grids with 2 arc min resolution the grids include data from all the major ocean basins as well as detailed reconstructions of back arc basins the age spreading rate and asymmetry at each grid node are determined by linear interpolation between adjacent seafloor isochrons in the direction of spreading ages for ocean floor between the oldest identified magnetic anomalies and continental crust are interpolated by geological estimates of the ages of passive continental margin segments the age uncertainties for grid cells coinciding with marine magnetic anomaly identifications observed or rotated to their conjugate ridge flanks are based on the difference between gridded age and observed age the uncertainties are also a function of the distance of a given grid cell to the nearest age observation and the proximity to fracture zones or other age discontinuities asymmetries in crustal accretion appear to be frequently related to asthenospheric flow from mantle plumes to spreading ridges resulting in ridge jumps toward hot spots we also use the new age grid to compute global residual basement depth grids from the difference between observed oceanic basement depth and predicted depth using three alternative age depth relationships the new set of grids helps to investigate prominent negative depth anomalies which may be alternatively related to subducted slab material descending in the mantle or to asthenospheric flow a combination of our digital grids and the associated relative and absolute plate motion model with seismic tomography and mantle convection model outputs represents a valuable set of tools to investigate geodynamic problems

a simple global model of plate dynamics and mantle convection cooling and thickening of lithospheric plates with age and subduction result in large scale horizontal density contrasts tending to drive plate motions and mantle flow we quantify the driving forces associated with these density contrasts to determine if they can drive the observed plate motions first two dimensional models are computed to evaluate the effects of assumed rheologies and boundary conditions we are unable to obtain platelike behavior in viscous models with traction free boundary conditions the piecewise uniform velocities distinctive of plate motion can be imposed as boundary conditions and the dynamic consistency of the models evaluated by determining if the net force on each vanishes if the lithosphere has a newtonian viscous rheology the net force on any plate is a strong function of the effective grid spacing used leading to ambiguities in interpretation incorporating a rigid plastic lithosphere which fails at a critical yield stress into the otherwise viscous model removes these ambiguities the model is extended to the actual three dimensional spherical plate geometry the observed velocities of rigid plastic plates are matched to the solution of the viscous stokes equation at the lithosphere asthenosphere boundary body forces from the seismically observed slabs from the thickening of the lithosphere obtained from the actual lithospheric ages and from the differences in structure between continents and oceans are included interior density contrasts such as those resulting from upwellings from a hot bottom boundary layer are assumed to occur on a scale small compared to plate dimensions and are not included the driving forces from the density contrasts within the plates are calculated and compared to resisting forces resulting from viscous drag computed from the three dimensional global return flow and resistance to deformation at converging boundaries the rms residual torque is 30 of the driving torque the density contrasts within the plates themselves can reasonably account for plate motions body forces from convection in the interior may provide only a small net force on the plates at converging boundaries the lithosphere has a yield stress of 100 bars drag at the base of the plates is 5 bars and resists plate motion the net driving forces from subducting slabs and collisional resistance are localized and approximately balance driving forces from lithospheric thickening are distributed over the areas of the plates as is viscous drag the approximate balance of these two forces predicts plate velocities uncorrelated with plate area as observed the model represents a specific case of boundary layer convection the dynamical results are consistent with either upper mantle or mantle wide convection

palaeomagnetic excursions aborted reversals and transitional fields recordings of palaeomagnetic excursions have revealed apparent field behaviour ranging from rather erratic directional movements and loopings1 4 to single highly defined events5 7 excursions of the latter variety show what seems to be a rapid change in direction such that the path of the associated virtual geomagnetic poles vgps is well constrained in longitude such behaviour is not unlike that observed at the onset of some recorded polarity transitions7 9 indeed it has been suggested that excursions may occur during unsuccessful or aborted reversals2 5 7 10 we show here that available records of palaeomagnetic excursions together with our present understanding of field behaviour associated with geomagnetic reversals strongly support this hypothesis

late mesozoic and cenozoic palaeomagnetism of australia iii bias corrected pole paths for australia antarctica and india summary palaeomagnetic results from part i of this study and their analysis in part ii are combined to eliminate bias from the cenozoic apparent polar wander path for australia a bias due to non dipole components in past geomagnetic fields or for poles calculated from hot spot data due to the motion of hot spots relative to the earth s rotational axis this path is extended in approximately bias free form to the late mesozoic and indicates a significant change in the drift direction of the continent between 26 and about 60 ma the bias corrected australian path is used first with seafloor spreading data for the southern ocean to derive a corresponding late mesozoic cenozoic pole path for antarctica the latter shows that the antarctic drift direction reversed in the early tertiary it is suggested that the early tertiary directional changes of both australia and antarctica are part of a global reorganization of plates during the eocene postulated by rona richardson cande mutter and patriat achache next the australian path is compared with hot spot data from the african and australian plates indicating a movement of the hot spots relative the earth s rotational axis during the cenozoic the direction of this movement is found to be consistent with previous results from other parts of the world finally the australian path is used together with non dipole components in the geomagnetic field to explain a prominent westward displacement of the mid and late cenozoic poles of india relative to those of australia because of uncertainties in the original poles and in the analysis the present results are likely to contain appreciable errors nevertheless their consistency with independent findings supports the dipole quadrupole model of part ii for mid and late cenozoic geomagnetic fields

effective petroleum source rocks of the world stratigraphic distribution and controlling depositional factors six stratigraphic intervals representing one third of phanerozoic time contain petroleum source rocks that have provided more than 90 of the world s discovered original reserves of oil and gas in barrels of oil equivalent the six intervals are 1 silurian generated 9 of the world s reserves 2 upper devonian tournaisian 8 of reserves 3 pennsylvanian lower permian 8 of reserves 4 upper jurassic 25 of reserves 5 middle cretaceous 29 of reserves and 6 oligocene miocene 12 5 of reserves this uneven distribution of source rocks in time displays no obvious cyclicity and the factors that controlled the formation of source rocks vary from interval to interval maps that show facies structural forms and petroleum source rocks were prepared for this study analysis of the maps indicates that several primary factors controlled the areal distribution of source rocks their geochemical type and their effectiveness i e the amounts of discovered original conventionally recoverable reserves of oil and gas generated by these rocks these factors are geologic age paleolatitude of the depositional areas structural forms in which the deposition of source rocks occurred and the evolution of biota the maturation time of these source rocks demonstrates that the majority of discovered oil and gas is very young almost 70 of the world s original reserves of oil and gas has been generated since the coniacian and nearly 50 of the world s petrole m has been generated and trapped since the oligocene the term petroleum as used in this study includes oil gas condensate and gas but does not include bitumen and other solid and semisolid oil derivatives

a revised identification of the oldest sea floor spreading anomalies between australia and antarctica we propose that magnetic anomalies south of australia and along the conjugate margin of antarctica that were originally identified as anomalies 19 to 22 may be anomalies 20 to 34 the original anomaly identification has two troublesome aspects 1 it does not account for an extra anomaly between anomalies 20 and 21 and 2 it provides no explanation for the rough topography comprising the diamantina zone with our revised identification there is no extra anomaly and the diamantina zone is attributed to a period of very slow spreading 4 5mm yr half rate between 90 and 43 m y the ages bounding the interval of slow spreading 90 and 43 m y correspond to times of global plate reorganizations our revised identification opens up the possibility that part of the magnetic quiet zone south of australia formed during the cretaceous long normal polarity interval breakup of australia and antarctica probably occurred sometime between 110 and 90 m y b p the breakup unconformity identified by falvey in the otway basin may correspond to a eustastic sea level change

magnetic ages of some indian laterites abstract the results of an extensive palaeomagnetic investigation of laterites from peninsular india are described from 62 samples 693 specimens were step wise thermally demagnetised to eliminate secondary magnetisations the ages of laterite formation were estimated after calculation of pole positions from site mean directions and comparison with the mesozoic tertiary apparent polar wander path apwp for india the high altitude laterites have undergone a complex magnetic history during the late cretaceous and early tertiary the low altitude laterites are mid to late tertiary in age a fundamental mechanism in laterite formation and preservation is suggested when the indian laterite results are compared with those from australia they are seen to be consistent with the relative timing of the northward drift of india and australia

large scale lithospheric stress field and topography induced by global mantle circulation stresses in the lithosphere are one indication of processes in the earth interior here we present a calculation of largescale lithospheric stresses caused by global mantle circulation the mantle flow field is calculated based on density structures inferred from global seismic tomography predicted principal stress directions are compared to interpolations based on observed stresses agreement between predictions and observations is often good in regions where lithospheric stresses and mantle tomography are well constrained predicted magnitudes of scalar stress anomalies vary more strongly than predicted stress directions for various tomographic models hotspots preferentially occur in regions where calculated stress anomalies are tensile or slightly compressive results do not strongly depend on radial mantle viscosity structure lithospheric rheology viscous or elastic or plate motion model the model also predicts the directions of motion well for most plates misfits in the predicted magnitudes can be explained qualitatively stress anomalies due to causes within the lithosphere oceanic cooling with age variations in crustal thickness topography isostatically compensated at subcrustal levels are also computed predicted stress directions in the absence of mantle flow can explain observations almost as well as mantle flow nevertheless current models of mantle flow are largely in accord with interpolations of observed principal stress directions and the observed plate motions fl 2001 elsevier science b v all rights reserved

the legacy of the ne german basin reactivation by compressional buckling in contrast to previously published models for the area the seismic reflection moho is essentially flat beneath the ne german basin along the dekorp deep seismic profile basin 96 this raises the question whether the present structure of the crust and flat moho reflect the initial formation of the basin or modification by more recent processes a 2d flexural model developed for a thin elastic plate is presented together with lithospheric strength profiles calculated along the basin 9601 reflection seismic line the analysis shows a southward decrease of lithospheric strength below the basin with a lithospheric decoupling between the crust and the mantle the modelling supports the hypothesis that the present moho topography is caused by flexural buckling which caused subsidence of the ne german basin during the upper cretaceous early cenozoic inversion event this suggests that the basin is in isostatic disequilibrium and that compressive stresses are required to keep the present basin geometry

paleomagnetism and tectonics of malaita solomon islands malaita in the solomon islands is the emergent expression of the pacific province a geologically distinct suspect terrane which is commonly held to be the margin of the ontong java plateau a thickened portion of pacific plate overthrust onto the rest of the solomon islands arc during a late miocene reversal of the polarity of the arc subduction of the australian plate replaced pacific plate subduction during this event and the solomon islands arc was transferred from the australian plate to the pacific plate a paleomagnetic survey of the eastern solomon islands included sampling in southern malaita magnetostratigraphic dating gives an age of 5 8 ma for the haruta calcisiltite hada calcisiltite facies change on malaita this facies change resulted from renewed volcanic activity following the initiation of australian plate subduction paleomagnetic poles from two pre pliocene units do not lie near the pacific apparent polar wander path apwp as the conventional model would suggest but rather fall on the australian apwp suggesting that the pacific province developed as a part of the australian plate correction for 6 5 ma of pacific australia relative motion produces an improved very close fit to the australian apwp consistent with the transfer of malaita along with the rest of the arc to the pacific plate at about that time magnetic paleolatitudes from a dsdp hole on the ontong java plateau which disagree with usually accepted pacific tertiary motion also fail to match the malaitan data the possibility that malaita could be a part of an ontong java sub plate somehow detached from the rest of the pacific plate can be discounted malaita and the rest of the pacific province arose in the fore arc of the originally north east facing arc collision of the ontong java plateau with the trench slowed subduction of the pacific plate and began subduction of the australian plate below the arc both subduction zones may have been active for a period beginning at about 10 ma and ending at about 3 ma until pacific plate subduction broke down and the pacific province was subsequently uplifted and deformed

global basin classification system a proposed system classifies sedimentary basins worldwide into specific as well as general categories the geologic history of each basin may be subdivided into cycles using three parameters basin forming tectonics depositional sequences and basin modifying tectonics sedimentary basins may be simple with one or two tectonic sedimentary cycles or they may be complex polyhistory basins with many different cycles and events there are eight simple cycle types in this classification which cover continental continental margin and oceanic areas the eight basic cycle types their depositional fills and tectonic modifiers have been given letter and number symbols so that the specific geologic history of each basin may be written as a formula these formulas may then e compared and similarities or differences between basins noted

geologic and palaeomagnetic constraints on the formation of weathered profiles near inverell eastern australia abstract we use geologic and palaeomagnetic observations to constrain the timing and duration of weathering of the oakwood bauxite which outcrops in the new england region of new south wales australia the bauxite is developed on and overlain by mafic volcanic flows prior geochronologic results from surrounding regions indicate that age of these flows and thus the age of the bauxite is most likely between 18 and 26 ma though volcanics elsewhere in the central volcanic province have a much greater range of between 6 and 56 ma similarly comparison of a new palaeomagnetic pole computed from the bauxite pole latitude 75 4 n longitude 311 3 e n 58 a95 4 4 with the australian apparent polar wander path gives estimated ages of 21 27 ma individual samples of the bauxite have both normal and reversed polarity components of magnetization which beside providing a positive palaeomagnetic reversal test suggests that the duration of weathering exceeded 10 000 years and more likely lasted several million years our results suggest that the oakwood region had a palaeoclimate and palaeoenvironment that was conducive for deep weathering over a significant period in a the time interval from the mid oligocene to the early miocene

investigating the stratigraphy and palaeoenvironments for a suite of newly discovered mid cretaceous vertebrate fossil localities in the winton formation queensland australia the winton formation of central queensland is recognized as a quintessential source of mid cretaceous terrestrial faunas and floras in australia however sedimentological investigations linking fossil assemblages and palaeoenvironments across this unit remain limited the intent of this study was to interpret depositional environments and improve stratigraphic correlations between multiple fossil localities within the preserved winton formation in the eromanga basin including isisford lark quarry and bladensburg national park twenty three facies and six repeated facies associations were documented indicating a mosaic of marginal marine to inland alluvial depositional environments these developed synchronously with the final regression of the eromanga seaway from central australia during the late albian early turonian investigations of regional and local scale structural features and outcrop core and well analysis were combined with detrital zircon provenance signatures to help correlate stratigraphy and vertebrate faunas across the basin significant palaeoenvironmental differences exist between the lower and upper portions of the preserved winton formation warranting informal subdivisions a lower tidally influenced fluvial deltaic member and an upper inland alluvial member this work further demonstrates that the isisford fauna is part of the lower member of the preserved winton formation whereas fossil localities around winton including lark quarry and bladensburg national park are part of the upper member of the winton formation these results permit a more meaningful framework for both regional and global comparisons of the winton flora and fauna

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