silicate weathering rates decoupled from the 87sr 86sr ratio of the dissolved load during himalayan erosion this study establishes that carbonate weathering dominates the supply of sr with elevated 87sr 86sr ratios in the bhote kosi sun kosi river system central nepal a major himalayan tributary to the ganges the dissolved load of the bhote kosi sun kosi displays a rapid increase in the 87sr 86sr ratio in its lower section downstream of the main central thrust a feature common to other himalayan tributaries of the ganges mass balance analysis of the contributing sources to the dissolved load identifies the weathering of palaeoproterozoic impure carbonates comprised largely of dolomite and mica from the lesser himalaya as the most significant lithological control upon elevated 87sr 86sr ratios in situ laser ablation analysis of the dolomite component yields 87sr 86sr ratios of 0 93 to 1 11 indistinguishable from bulk rock this confirms the presence of a highly soluble source of radiogenic strontium and suggests that diffusive exchange during a protracted metamorphic history has homogenised sr isotopes between silicate and carbonate phases within the assemblage weathering of the carbonate component of such rocks has yielded unusually high 87sr 86sr at significant sr fluxes in the dissolved load approximately 60 of the impact of the bhote kosi sun kosi on the marine 87sr 86sr ratio can be traced to weathering of this carbonate since similar lithologies outcrop within the catchments of most himalayan tributaries that feed the ganges and brahmaputra rivers the presence of such radiogenic carbonates undermines the inference that the impact of these rivers on sr isotopes in seawater is indicative of high silicate weathering rates that result from the uplift of tibet and the himalaya

paleobotanical evidence for near present day levels of atmospheric co2 during part of the tertiary understanding the link between the greenhouse gas carbon dioxide co 2 and earth9s temperature underpins much of paleoclimatology and our predictions of future global warming here we use the inverse relationship between leaf stomatal indices and the partial pressure of co 2 in modern ginkgo biloba and metasequoia glyptostroboides to develop a co 2 reconstruction based on fossil ginkgo and metasequoia cuticles for the middle paleocene to early eocene and middle miocene our reconstruction indicates that co 2 remained between 300 and 450 parts per million by volume for these intervals with the exception of a single high estimate near the paleocene eocene boundary these results suggest that factors in addition to co 2 are required to explain these past intervals of global warmth

mid miocene propagation of the yellowstone mantle plume head beneath the columbia river basalt source region columbia river flood basalt volcanism is the product of mid miocene distortion of the yellowstone mantle plume head against the precambrian margin of north america the overall migration pattern of columbia river basalt vents reflects northward propagation of the plume head beneath the west southwest migrating north american plate thermal uplift mimics the vent migration over the 1 5 m y of grande ronde basalt extrusion the projected crest of the plume head migrated 105 km 7 cm yr from the chief joseph dike swarm east oortheast into the clearwater embayment where uplift occurred over the same period at a rate of 0 67 mm yr chemical variations reflect progressive melting of the plume and mantle lithosphere followed by the mixing of these components with an enriched source from the overriding craton rapid thickening of the plume head against the cratonic margin led to decompressional melting and magma rise beneath a thin oceanic lithosphere of accreted terranes

the late neogene 87sr 86sr record of lowland himalayan rivers fossil shells and paleosol carbonate from ancestral himalayan river deposits provide a 87 sr 86 sr record of lowland himalayan river water during the late neogene reconstructed 87 sr 86 sr river values increased sharply in the late miocene probably marking the beginning of exhumation of high 87 sr 86 sr metalimestones more in the central than in the western himalayas these results imply that the marine 87 sr 86 sr record may not be a proxy for silicate weathering or consumption of atmospheric co 2 resulting from that weathering

marked decline in atmospheric carbon dioxide concentrations during the paleogene the relation between the partial pressure of atmospheric carbon dioxide pco2 and paleogene climate is poorly resolved we used stable carbon isotopic values of di unsaturated alkenones extracted from deep sea cores to reconstruct pco2 from the middle eocene to the late oligocene approximately 45 to 25 million years ago our results demonstrate that pco2 ranged between 1000 to 1500 parts per million by volume in the middle to late eocene then decreased in several steps during the oligocene and reached modern levels by the latest oligocene the fall in pco2 likely allowed for a critical expansion of ice sheets on antarctica and promoted conditions that forced the onset of terrestrial c4 photosynthesis

upper mantle structure along a profile from oslo noress to helsinki to leningrad based on explosion seismology abstract waveforms from the noress array were analyzed for 147 industrial explosions during the 1985 to 1988 period along a profile running east from oslo noress to helsinki to leningrad ohl profile the events were 250 to 1300 km from noress and had local magnitude in the range 2 0 to 3 5 event locations and origin times constrained by the university of helsinki9s regional seismic network provide a reliable basis for travel time estimation at noress we also used data recorded by norsar in 1979 for three shots on the fennolora north south long range seismic profile which were near the ohl profile analysis of mantle p wave signals from the explosions showed that first arrivals could be traced continuously to a distance of 750 to 800 km where there is a cutoff and shift of approximately 2 0 to 2 5 sec in the travel time curve and an increase in average apparent velocity interpretation of the observed travel times and waveforms for this profile suggests a low velocity zone from approximately 105 to 135 km depth combined analysis of the seismic data with a bouguer gravity map indicates the presence in the upper mantle of a high velocity high density body of linear extent approximately from 200 to 300 to 500 to 600 km east of the noress array it is postulated that this body may represent the root of an ancient volcanic system in which lighter silicic constituents were depleted from the upper mantle during the eruptive phase

late cenozoic uplift of mountain ranges and global climate change chicken or egg the high altitudes of most mountain ranges have commonly been ascribed to late cenozoic uplift without reference to when crustal thickening and other tectonic processes occurred deep incision and recent denudation of these mountain ranges abundant late cenozoic coarse sediment near them and palaeobotanical evidence for warmer climates where high mountain climates today are relatively cold have traditionally been interpreted as evidence for recent uplift an alternative cause of these phenomena is late cenozoic global climate change towards lower temperatures increased alpine glaciation a stormier climate and perturbations to humidity vegetative cover and precipitation

controls on the erosion of cenozoic asia and the flux of clastic sediment to the ocean rates of continental erosion may be reconstructed from variations in the rate of accumulation of clastic sediment most of which lies offshore global rates of marine sedimentation are usually considered to have reached a maximum after 3 4 ma driven by enhanced erosion in a variable glacial interglacial climate however a new compilation of seismic data from the marginal seas of asia now shows that only the red river reached its historic peak after 4 ma sediment flux from asia first peaked in the early middle miocene 24 11 ma well before the initiation of a glacial climate indicating that rock uplift and especially precipitation are the key controls on erosion at least over long periods of geologic time reconstructions of weathering in east asia show that faster erosion correlates with more humid warm climates in the early middle miocene changing to less erosive drier climates after 14 ma when antarctic glaciation begins average rates of sedimentation on most east asian continental margins since 1 8 ma are 5 6 times less than the modern fluvial flux implying that the flux to the oceans varies sharply on short timescales and is not always buffered over timescales of 10 4 yr by storage in flood plains

a 20 ma pollen record of east asian summer monsoon evolution from guyuan ningxia china abstract pollen analysis was conducted on the fluviolacustrine sediments from the east side of the liupan mountains a relatively monsoon sensitive region and provided for the first time a continuous evolutionary history of vegetation and climate in east china during the neogene the pollen record spanning the last 20 ma indicates that the vegetation and thus east asian summer monsoon evolution can be divided into three stages 20 13 14 25 ma 14 25 11 35 ma and 11 35 0 08 ma in spite of general dominance of steppe throughout the neogene during the period 20 13 14 25 ma the pollen assemblage was characterized by high abundance of artemisia and small amounts of temperate to subtropical deciduous broad leafed trees such as juglans carya quercus and betula suggesting that the east asian summer monsoon was generally strong the interval from 14 25 to 11 35 ma was marked by a significant decline in the east asian summer monsoon as indicated by artemisia gradually replaced by humulus and halophytic chenopodiaceae nitraria and ephedra also reached high values in this period since 11 35 ma ago percentages of halophytes dominated by chenopodiaceae and tamaricaceae maintained a high mean value of about 40 revealing a weak intensity of east asian summer monsoon the general weakening of the monsoon circulation during the neogene and the significant monsoon decline during the late middle miocene in particular might link with the global cooling trend probably through two mechanisms cooling and ice sheet expansion over the polar region caused an increase in meridional temperature gradients leading to the southward retreat of the monsoon circulation the global cooling may have also reduced the amount of water vapor held in the atmosphere and led to both additional cooling and further weakening of the east asian summer monsoon the cause for a short lived resumption during the period 1 0 0 8 ma is under investigation

the structure of the baltic shield region on the basis of dss and earthquake data the lithospheric models obtained for the baltic shield by using deep seismic soundings are discussed and results from different parts of the shield are compared with models achieved by the investigation of surface waves and of p to s converted waves the results are found to agree rather well with each other particularly with regard to the first interface at a depth of 10 15 km and the whole thickness of the crust c 40 km the macroseismic focal depth determinations of regional earthquakes are correlated with lithospheric structure the main maximum in the focal depth distributions of finnish earthquakes occur at a depth of 10 12 km the geographical distribution of the earthquake epicentres suggests several seismo active zones in the northern baltic shield one new finding in this field concerns the lapland zone which runs in a north westerly direction

geomorphology as a first order control on the connectivity of riparian ecohydrology abstract geomorphic controls on ecohydrological connections while implicit in processes such as the derivation of transpired water from alluvial aquifers have not been systematically investigated in this article we test the hypothesis that geomorphic setting is an important control on groundwater sourced riparian evapotranspiration et through a statistical investigation of 30 years of daily flow data monthly precipitation data and semimonthly satellite images at fourteen 1 km long river reaches representing a range of geomorphic settings in the semiarid landscape of new mexico usa we focus on correlations between vegetation greenness as a surrogate for vigor and transpiration rates interannual variability in flow and rainfall characteristics and valley metrics such as width slope and concavity sites were considered individually and in groups based on classification as perennial or intermittent principal component analysis pca was used to distill related metrics into significant uncorrelated interpretable underlying variables components were interpreted in the same manner as a factor analysis and were found to include overall magnitude of greenness within summer variability of greenness overall wetness rain vs flow dominance snowmelt vs monsoon dominance and mountain vs basin geomorphic setting among others to broadly test the hypothesis that geomorphology affects the relationship between wetness and greenness best subset regressions were constructed for the full range of sites and groups using all wetness and geomorphic components as potential predictor variables and greenness metrics as response variables from our analysis we draw two main conclusions 1 including geomorphic parameters provides new information that is nonredundant with precipitation and flow parameters in predicting vegetation extent and vigor the parameters especially curvature may indicate causal processes such as increased soil moisture availability on concave surfaces with convergent flow paths or they may provide correlative information on the groundwater setting gaining vs losing 2 when considering groups of sites the dominance of precipitation over stream flow in delivering moisture was a predictor of high greenness but this was not the case for any individual sites this indicates that while greener communities developed in sites with greater average precipitation at any single site the vegetation was able to adapt to either local precipitation or streamflow delivery of moisture in a given year and only the magnitude of the moisture delivered affected vegetation vigor these findings emphasize the versatility of riparian vegetation to utilize soil moisture in convergent geomorphic settings or wet time periods moisture that may otherwise tend to evaporate

mass accumulation rates in asia during the cenozoic summary this work establishes estimates of mass accumulation rates in 18 mostly offshore sedimentary basins in asia since the beginning of the cenozoic 66 ma the estimates were derived from isopach maps cross sections and drill holes or stratigraphic columns assuming regional similarity of the strata average solid phase volumes and accumulation rates were calculated for nine epochs approximately corresponding to geological periods palaeocene 66 58 ma eocene 58 37 ma oligocene 37 30 and 30 24 ma miocene 24 17 17 11 and 11 5 ma pliocene 5 2 ma and quaternary 2 0 ma these rates shed new light on the geological history of asia since the onset of the collision of india with asia 50 ma the overall average accumulation rates curve for asian sedimentary basins since the beginning of the tertiary shows an exponential form with slow accumulation rates less than 0 5 106 km3 myr 1 until the beginning of the oligocene more than 15 myr after the onset of the collision from the oligocene onwards rates increase quickly in an exponential manner reaching their maximum values in the quaternary more than 1 5 106 km3 myr 1 from these observations we suggest that extrusion and crustal shortening are complementary processes that have been successively dominant throughout the india eurasia collision history at smaller scales one may distinguish between independent histories at the subcontinental and basin scales this permits a comparison of the relative importance of tectonic and climatic erosion processes affecting the different mountain belts of asia during the cenozoic

post collisional sediment budget history of the alps tectonic versus climatic control based on the sediment budget of the eastern swiss and western alps since the oligocene the regional tectonic evolution has been identified as the dominant factor it is superimposed on the influence of both regional and global climate change and global sea level change during late pliocene and pleistocene times climate became the dominant factor because of cyclic glaciations the early post collisional history of the alps is characterized by a doubling of sediment discharge rates around the rupelian chattian boundary this increase is attributed to isostatic re adjustment either after large scale thermal reorganization of the lithosphere related to slab break off or to crustal thickening as continental crust became subducted from middle oligocene to late miocene times the overall trend of sediment discharge rates in the entire alps was modified only during relatively short lived phases these are characterized by an increase in aquitanian ca 23 21 ma and late burdigalian times ca 18 16 4 ma and a decrease in early to middle burdigalian 21 19 ma and langhian to serravalian times 16 4 12 ma an important still ongoing period of uplift reflected by rapidly increasing sediment discharge rates started in latest miocene times in the swiss and western alps and affected the eastern alps some 2 million years later the reason for this uplift is not clear but deep seated lithospheric processes appear to be likely

the late cenozoic uplift climate change paradox the geologic evidence for worldwide uplift of mountain ranges in the neogene is ambiguous estimates of paleoelevation vary according to whether they are based on the characteristics of fossil floras on the masses and grain sizes of eroded sediments or on calculations of increased thickness of the lithosphere as a result of faulting detrital erosion rates can be increased both by increased relief in the drainage basin and by a change to more seasonal rainfall patterns the geologic record provides no clear answer to the question whether uplift caused the climatic deterioration of the neogene or whether the changing climate affected the erosion system in such a way as to create an illusion of uplift we suggest that the spread of c4 plants in the late miocene may have altered both the erosion and climate systems these changes are responsible for the apparent contradictions between data supporting uplift and those supporting high elevations in the past

the himalayas organic carbon burial and climate in the miocene cooling ages of rock in the himalayas imply that rapid exhumation between the main central thrust system and the south tibetan detachment system occurred between 21 and 17 ma the generation of relief and enhanced weathering which followed this event may have resulted in a pronounced increase in the delivery of dissolved strontium carbon phosphorus and other chemical weathering products to the ocean richter et al 1992 the increased supply of nutrients stimulated productivity in oceanic upwelling zones and expansion of the oxygen minimum zone leading to enhanced burial and preservation of organic matter in the monterey formation and other deposits from this interval a downdraw of atmospheric co2 associated with enhanced chemical weathering rates and organic matter burial may have led to global cooling and the expansion of the antarctic ice sheet by 15 ma the above scenario differs from the monterey hypothesis of vincent and berger in that co2 downdraw is primarily via silicate weathering rather than organic carbon burial and that organic carbon burial is driven by increased delivery of nutrients to the ocean rather than by stronger upwelling a carbon mass balance calculation which assumes that river fluxes have been increasing over the last 40 ma predicts that absolute organic carbon burial increased over this interval while at the same time the fraction of carbon buried as organic matter versus carbonate decreased this implies that the organic carbon cycle has acted as a net source of co2 to the atmosphere over the late cenozoic

extreme weathering erosion during the miocene climatic optimum evidence from sediment record in the south china sea investigating the interplay between continental weathering and erosion climate and atmospheric co 2 concentrations is significant in understanding the mechanisms that force the cenozoic global cooling and predicting the future climatic and environmental response to increasing temperature and co 2 levels the miocene represents an ideal test case as it encompasses two distinct extreme climate periods the miocene climatic optimum mco with the warmest time since 35 ma in earth s history and the transition to the late cenozoic icehouse mode with the establishment of the east antarctic ice sheet however the precise role of continental weathering during this period of major climate change is poorly understood here we show changes in the rates of miocene continental chemical weathering and physical erosion which we tracked using the chemical index of alteration cia and mass accumulation rate mar respectively from ocean drilling program odp site 1146 and 1148 in the south china sea we found significantly increased cia values and terrigenous mars during the mco ca 17 15 ma compared to earlier and later periods suggests extreme continental weathering and erosion at that time similar high rates were revealed in the early middle miocene of asia the european alps and offshore angola this suggests that rapid sedimentation during the mco was a global erosion event triggered by climate rather than regional tectonic activity the close coherence of our records with high temperature strong precipitation increased burial of organic carbon and elevated atmospheric co 2 concentration during the mco argues for long term close coupling between continental silicate weathering erosion climate and atmospheric co 2 during the miocene citation wan s w m kurschner p d clift a li and t li 2009 extreme weathering erosion during the miocene climatic optimum evidence from sediment record in the south china sea geophys res lett 36 l19706 doi 10 1029 2009gl040279

palaeoclimate and vegetation change in serbia during the last 30 ma abstract in the present study 14 published megafloras from the serbian cenozoic are analyzed with respect to vegetation type palaeoclimate and palaeogeographic settings the floras cover a time span from the oligocene to the late miocene the results obtained are compared with continental climate records from other parts of europe and discussed in the context of global climate change to obtain a quantitative palaeoclimate record a total of seven different climate variables is calculated for each of the floras using the coexistence approach it is shown that basic patterns of vegetation change such as the immigration of arcto tertiary deciduous floristic elements during the early miocene and the decreasing diversity of laurophyllous taxa during the late miocene are ruled by climate change and a changing palaeogeography the serbian cenozoic climate record shows a steep cooling gradient during the oligocene that is most probably is connected to a northward movement of tectonic plates the globally observed middle miocene climate optimum and the late miocene cooling are well reflected according to the palaeotemperatures calculated a warm temperate climate existed in serbia throughout the time span examined the late miocene cooling is most pronounced in winter temperatures and is connected to increasing seasonality precipitation rates obtained for the serbian cenozoic especially those of the warmest and wettest months tend to be lower when compared to the central european cenozoic according to climate analysis and the interpretation of vegetational data there is evidence for regionally drier conditions and increased seasonality of precipitation in the time span from the late badenian to the early sarmatian

oceanic crust production and climate during the last 100 myr in order to evaluate the possible influence of oceanic crust production on climatic changes during the past 100myr variations in total oceanic crust for this period including production at mid ocean ridges oceanic plateaus and back arc basins were calculated using the most recent and accurate time scales the rates presented here differ from those of larson 1991a b on cenozoic fluctuations and show that 1 maximum production values occurred during the cenomanian palaeocene and late oligocene early miocene and 2 minimum values occurred in campanian maastrichtian late eocene and middle miocene significantly variations of oceanic crust production correspond with variations in the 18o of deep water benthic foraminifera maximum values of oceanic crust production correspond with minimum values of 18o and minimum production values with maximum values of 18o this latter synchronism suggests that changes in land sea relationships and atmospheric co2 related to major fluctuations in oceanic crust production were the main cause of mid cretaceous warming and late cretaceous cooling and of climatic quasi cycles having a periodicity of 33 38 million years over the last 100 myr this is the first report showing variations of ocean crust production synchronized with the cenozoic climate changes

cenozoic continental climatic evolution of central europe continental climate evolution of central europe has been reconstructed quantitatively for the last 45 million years providing inferred data on mean annual temperature and precipitation and winter and summer temperatures although some regional effects occur the european cenozoic continental climate record correlates well with the global oxygen isotope record from marine environments during the last 45 million years continental cooling is especially pronounced for inferred winter temperatures but hardly observable from summer temperatures correspondingly cenozoic cooling in central europe is directly associated with an increase of seasonality in contrast inferred cenozoic mean annual precipitation remained relatively stable indicating the importance of latent heat transport throughout the cenozoic moreover our data support the concept that changes in atmospheric co2 concentrations although linked to climate changes were not the major driving force of cenozoic cooling

structural regularities in the lithosphere of continents and plate tectonics abstract two fundamental but competing earth science concepts have been under discussion in russia the first one that of endogenous regimes is based on the assumption that permanent vertical relationships or long term interactions between the crust and upper mantle control crustal evolution significant horizontal movements of the lithosphere as required by the second concept that of global plate tectonics would destroy these crust mantle interactions certain regular features of the crust and upper mantle support the endogenous regime concept and are difficult to explain in terms of conventional plate tectonics in particular the close correlation between near surface features and deep 400 km mantle inhomogeneities suggests that many geological structures are deeply rooted in the mantle moreover geophysical studies have failed to reveal a well defined and continuous asthenosphere at relatively shallow depths 100 km that would allow lithospheric plates to be transported over large distances and the rheology of the lithosphere itself is found to be sufficiently inhomogeneous as to cast doubt on the principle of thin rigid plates in contrast palaeomagnetic and other data require that horizontal movements of many near surface geological structures must have taken place to explain this apparent contradiction it is suggested here that the crust and its connected deep root are capable of gliding along one of the deep mantle phase transition zones with respect to the inner earth

source mechanisms of moderate size earthquakes and stress orientation in mid plate south america summary fault plane solutions of six mid plate earthquakes with magnitudes ranging from 4 8 to 5 5 mb were determined using p wave first motion data and the relative amplitudes of short period teleseismic depth phases pp and sp these results together with previous studies show a predominance of reverse and strike slip faulting indicating horizontal compressional stresses in mid plate south america the orientation of the p axes however is not uniform in western and southwestern brazil the p axes are oriented approximately e w probably due to the nazca south america plate convergence in eastern brazil the direction of the p axes show more scatter but an average e w direction is consistent with the available data on the contrary in northern brazil the p axes of two events in the amazon basin trend approximately n s a direction perpendicular to the direction of absolute plate motion as well as to the relative plate motions nazca south america and south america africa

development of the east asian monsoon mineralogical and sedimentologic records in the northern south china sea since 20 ma we here reconstruct the past change of the east asian monsoon since 20 ma using samples from ocean drilling program odp site 1146 in the northern south china sea based on a multi proxy approach including a monomineralic quartz isolation procedure identification of clay minerals by x ray diffraction xrd and grain size analysis of isolated terrigenous materials terrigenous supply to odp site 1146 was dominated by changes in the strength of multiple sources and transport processes grain size data modeled by an end member modeling algorithm indicate that eolian dust from the and asian inland and fluvial input have contributed on average 20 and 80 of total terrigenous material to odp site 1146 respectively specifically about 40 53 of the total quartz feldspar and only 6 11 of the total clay is related to eolian supply at the study site detailed analysis of the sedimentary environment and clay minerals combined with previous studies shows that smectite originates mainly from luzon kaolinite from the pearl river and illite and chlorite from the pearl river taiwan and or the yangtze river the proportion and mass accumulation rate mar of the coarsest end member em1 interpreted as eolian dust ratios of illite chlorite smectite quartz feldspar and mean grain size of terrigenous materials at odp site 1146 were adopted as proxies for east asian monsoon evolution the consistent variation of these independent proxies since 20 ma shows three profound shifts in the intensity of east asian winter monsoon relative to summer monsoon as well as aridity of the asian continent occurred at similar to 15 ma similar to 8 ma and the youngest at about 3 ma in comparison the summer monsoon intensified contemporaneously with the winter monsoon at 3 ma the phased uplift of the himalaya tibetan plateau may have played a significant role in strengthening the asian monsoon at similar to 15 ma 8 ma and 3 ma c 2007 elsevier b v all rights reserved

geochemical and nd isotopic variations in sediments of the south china sea a response to cenozoic tectonism in se asia secular variations in geochemistry and nd isotopic data have been documented in sediment samples at odp site 1148 in the south china sea major and trace elements show significant changes at ca 29 5 ma and 26 23 ma whereas ond values show a single change at ca 26 23 ma increases in al ti al k rb sr and la lu ratios and a decrease in the th la ratio of the sediments beginning at 29 5 ma are consistent with more intense chemical weathering in the source region the abrupt change in nd isotopes and geochemistry at ca 26 23 ma coincides with a major discontinuity in the sedimentology and physical properties of the sediments implying a drastic change in sedimentary provenance and environment at the drill site comparison of the nd isotopes of sediments from major rivers flowing into the south china sea suggests that pre 27 ma sediments were dominantly derived from a southwestern provenance indochina sunda shelf and possibly northwestern borneo whereas post 23 ma sediments were derived from a northern provenance south china this change in provenance from southwest to north was largely caused by ridge jumping during seafloor spreading of the south china sea associated with a southwestward expansion of the ocean basin crust and a global rise in sea level thus the geochemical and nd isotopic changes in the sediments at odp site 1148 are interpreted as a response to a major plate reorganization in se asia at ca 25 ma b 2003 elsevier science b v all rights reserved

inversion of teleseismic p wave particle motions for crustal structure in fennoscandia abstract we test a model of the earth s crust by transforming the observed vertical component of the teleseismic p wave record into the synthetic radial component and comparing this with the observed radial component the optimum model can be found by minimizing the rms difference between the synthetic radial component and the observed one for a number of records in the time intervals several tens of seconds long we applied this method to long period records of norsar and some other seismograph stations in fennoscandia the search for the optimum models was performed by trial and error and by application of the iterative procedure based on the general method of solution of the ill posed inverse problems tikhonov and arsenin in comparison with the conventional spectral ratio analysis our techniques are more flexible and demonstrate a higher resolving power it is found that in the norsar siting area the crustal thicknesses are regulated by the variations of thickness of the granite layer which dominates in the crust this observation explains peculiarities of the gravity field in the oslo graben region a similar relation between the parameters of the crust is found in the eastern part of fennoscandia