dating the quaternary progress in luminescence dating of sediments abstract luminescence dating comprises a collection of numerical age techniques that are among the most significant chronological tools currently used in quaternary research this paper briefly reviews the key historical developments in luminescence dating from its roots in thermoluminescence dating of heated minerals to the development of optical dating methods for sunlight exposed sediments we describe the principles and practicalities of the various techniques commonly used in luminescence dating including multiple aliquot single aliquot and single grain procedures and we discuss some of the latest approaches to recognising and minimising potential errors in age estimation e g by means of component analysis and dose distribution methods in optical dating the overview also introduces the other papers in this special issue of quaternary science reviews which address a selection of important issues in basic research technique development and application of luminescence dating to critical questions in the geological and archaeological sciences illustrated with examples from around the world and the last million years of earth history

the late quaternary slip rate of the har us nuur fault mongolian altai from cosmogenic 10be and luminescence dating the altai range western mongolia accommodates nne ssw shortening across the northern india eurasia collision zone by dextral slip on faults trending nnw sse and anticlockwise vertical axis rotations of fault bounded blocks however fault slip rates and the way in which faulting evolves over time are poorly understood and form the motivation for this study we focussed on the har us nuur fault a major transpressional fault bounding the eastern margin of the altai three abandoned alluvial fan surfaces each displaced right laterally by the fault were targeted for dating with cosmogenic 10be and quartz optically stimulated luminescence osl the first surface a2 shows an exponential decrease in 10be with increasing depth with a significant inherited component modelling this profile yielded a minimum age of 74 1 ka material from the same sampling pit was dated at 19 ka with osl but we consider this younger age to be incorrect possibly due to feldspar contamination or abnormal quartz osl characteristics the a2 surface is displaced by 175 m implying a maximum dextral slip rate of 2 4 0 4 mm yr 1 a second fan surface f1 was dated at 6 ka with osl and shows little variation in 10be with depth consistent with this young age the inherited component is higher than for a2 indicating contrasting levels of inheritance for different periods of fan aggradation a final surface f2 shows scattered 10be concentrations and lacks material suitable for osl so cannot be dated precisely using the total vertical displacement across the fault we place the initiation of movement on the fault at 2 ma significantly later than the late oligocene to miocene 28 5 ma onset of shortening in the altai region this suggests that deformation in the altai has widened over time to incorporate new faults at the range margins such as har us nuur possibly because older faults in the range interior have rotated about vertical axes into orientations that require work to be done against gravity

zeolites in burial diagenesis and low grade metamorphic rocks many zeolite assemblages originated during burial and subsequent low grade metamorphism of rocks particularly those of volcaniclastic origin eskola 1939 first suggested this type of zeolitization and applied the term zeolite facies to assemblages formed under such low temperature and low pressure conditions although several definitions of the zeolite facies have been proposed over the years e g fyfe et al 1958 the phrase as used here includes both low grade metamorphic assemblages and zeolite assemblages formed successively during burial the regional occurrence of zeolites in sedimentary rocks was first recognized by coombs 1954 who made detailed petrographic studies of triassic tuffaceous greywackes and tuffs of andesitic to rhyolitic in composition in the taringatura area of new zealand coombs recognized a zonal arrangement of heulandite and analcime near the top of the sequence and heulandite and laumontite near the bottom he also recognized a similar progressive zeolitization with depth in clastic sediments in other orogenic belts the zeolite assemblages described by coombs represent a rather advanced stage of alteration as opposed to an earlier stage of zeolitization that was subsequently described in neogene silicic volcaniclastic rocks from japan in the latter rocks zones from top to bottom of fresh glass clinoptilolite mordenite analcime heulandite laumontite and albite were recognized utada 1965 1970 progressive zeolitization has also been reported as a result of the thermal effects of intrusive masses see seki et al 1969 and around volcanic calderas utada and ito 1989 recently boles 1991 described the low temperature formation of laumontite and stilbite in fractures and faults related to post jurassic folding and uplift of the southland syncline new zealand the physico chemical conditions of zeolite crystallization in burial diagenesis and low grade metamorphic environments can vary widely both borehole data see iijima 1995 and experimental results liou 1970 1971a b c

cosmic ray labeling of erosion surfaces in situ nuclide production rates and erosion models a number of in situ cosmogenic radionuclides and stable nuclides have been measured in natural exposed rock surfaces with a view to study their in situ production and rock erosion rates 1 the in situ radionuclides can be used for a high resolution tomography of the erosional history of an exposed surface two stable nuclides 3he 21ne and five radionuclides 10be 26al 36cl 14c 39ar having half lives in the range of 300 1 5 106 yr half life are measurable in many rock types a prerequisite for the application of the in situ nuclides for the study of erosional histories of surfaces is a knowledge of their production rates under different irradiation conditions altitude latitude irradiation geometry and shielding relative nuclide production rates can be determined fairly accurately using the extensive available data on cosmic ray neutrons 2 absolute nuclide production rates cannot generally be predicted with any accuracy because of lack of data on excitation functions of nuclides unless some normalization is possible as was done in the case of several cosmic ray produced isotopes in the atmosphere 3 based on a recent natural calibration experiment in which erosion free surfaces exposed to cosmic radiation for 11 000 yrs were sampled the absolute production rates of 10be and 26al in quartz have been accurately estimated for mountain altitudes in sierra nevada 4 the absolute production rates of 10be and 26al in quartz can therefore be estimated fairly accurately for any given latitude and altitude some measurements of 14c in rocks of low erosion rate 5 similarly allow an estimate of its production rate attempts made to measure the in situ production rates of 3he in rocks have not yet led to a convergent production rate in view of the importance of knowing the production rates of isotopes of he ne and ar i present here theoretical estimates of their production rates based on available cross section data i discuss the information that can be extracted from the study of the in situ nuclides in rocks useful parameters characterizing the exposure history of a rock surface are 1 the effective surface exposure age and 2 the time averaged erosion rate the implications of these parameters for single and multiple nuclide studies are discussed in terms of the erosion models considered

syn rift evolution of the pripyat trough constraints from structural and stratigraphic modelling the pripyat trough is a late devonian rift basin it forms part of the larger pripyat dniepr donets rift system which has a length in excess of 800 km and separates the ukrainian shield from the voronezh massif the pripyat trough contains a well resolved stratigraphic sub division within the syn rift basin fill sequence which allows the duration and rate of rifting to be determined using 2 d forward and reverse structural and stratigraphic modelling the analysis shows that rifting was extremely rapid sequential decompaction and flattening of 2 d cross sections has been applied to six syn rift time horizons between top upper devonian 364 ma and top middle devonian 377 ma and used to quantify the syn rift development of basin cross sectional area in time the evolution of basin cross sectional area shows that some initial rifting had occurred prior to the middle frasnian 369 ma however most rifting occurred in the famennian 367 364 ma forward syn rift modelling using the flexural cantilever model of rift basin formation has also been applied to quantify the magnitude of extension within the pripyat trough in time forward syn rift models are constrained by the intra syn rift flattened and decompacted cross sections and the observed evolution of the cross sectional area most rapid rift basin formation is shown to have occurred in the famennian with over 66 of basin cross sectional area forming in less than 5 myr and with approximately 80 or more of total extension occurring in less than 3 myr this period of most rapid extension during the famennian coincides with the most active period of volcanicity total devonian extension across the pripyat trough is estimated to be of the order of 11 14 km with a maximum stretching factor of approximately 1 12 extensional strain rates are estimated to be of the order of 0 8 10 15 s 1

on the causes of mass extinctions the temporal link between large igneous province lip eruptions and at least half of the major extinctions of the phanerozoic implies that large scale volcanism is the main driver of mass extinction here we review almost twenty biotic crises between the early cambrian and end cretaceous and explore potential causal mechanisms most extinctions are associated with global warming and proximal killers such as marine anoxia including the early middle cambrian the late ordovician the intra silurian intra devonian end permian and early jurassic crises many but not all of these are accompanied by large negative carbon isotope excursions supporting a volcanogenic origin most post silurian biocrises affected both terrestrial and marine biospheres suggesting that atmospheric processes were crucial in driving global extinctions volcanogenic atmospheric kill mechanisms include ocean acidification toxic metal poisoning acid rain and ozone damage and consequent increased uv b radiation volcanic darkness cooling and photosynthetic shutdown each of which has been implicated in numerous events intriguingly some of the most voluminous lips such as the oceanic plateaus of the cretaceous were emplaced with minimal faunal losses and so volume of magma is not the only factor governing lip lethality the missing link might be continental configuration because the best examples of the lip extinction relationship occurred during the time of pangaea many of the proximal kill mechanisms in lip extinction scenarios are also potential effects of bolide impact including cooling warming acidification and ozone destruction however the absence of convincing temporal links between impacts and extinctions other than the chicxulub cretaceous example suggests that impacts are not the main driver of extinctions with numerous competing extinction scenarios and the realisation that some of the purported environmental stresses may once again be driving mass extinction we explore how experimental biology might inform our understanding of ancient extinctions as well as future crises

reappraisal of deep seismic reflection profile viii across the pripyat trough two deep 24 s multi channel seismic reflection profiles each 200 km in length were shot across the pripyat trough a late devonian rift basin in belarus in the 1980s by the polessian geophysical expedition of the former soviet union additional post stack processing and migration on one of these profile viii has been applied at uppsala university and allows a re evaluation of the crustal structure of the pripyat trough with particular focus on the deeper parts previous interpretations showed numerous steeply dipping faults extending from the surface to depths of 30 40 km and sometimes penetrating into the mantle which was defined to be located at the top of a reflective zone beginning at about 10 s twt this reflective zone recorded to depths of 16 s twt was interpreted as a mixture of crustal and mantle rocks based on the original stacked section and the further processing the reflective zone is reinterpreted to be reflective lower crust not upper mantle and the moho is identified to be at 45 50 km about 15 s twt the major basin bounding faults appear to be listric at depth and sole into the top of the reflective lower crust rather than be truncated by it the newly interpreted crustal structure is consistent with a model of continental rifting involving brittle failure in a thick upper crustal layer and ductile shear in the lowermost crust with some degree of detachment between crust and mantle within the lower crustal ductile layer

frasnian famennian biotic crisis undervalued tectonic control the prime cause of the late devonian kellwasser crisis culminating in a mass extinction event near the frasnian famennian f f boundary remains conjectural nevertheless rapid sea level fluctuations of uncertain origin during tectono eustatic highstand paired with repeated oceanic anoxia and climatic changes are usually thought at present to be one of the main immediate triggers the cathles hallam model of stress induced changes in plate density accompanying rapid rift formation furnishes an alternative for understanding the enigmatic sudden eustatic variations in the non glacial time late devonian tectonic extension causing rifting and volcanicity appears to be strongly marked in several regions of eurasia particularly in kazakhstan and eastern laurussia all larger devonian continents were more or less tectonically affected a subtle record of this tectonic rearrangement is implied even for distant and apparently quiet carbonate platforms in local extensional block faulting and tilting hydrothermal mineralisation geochemical anomalies and localized blooms of siliceous biota interpreting the late frasnian regressive transgressive pattern in terms of the cathles hallam tectono eustatic model two major rifting events are hypothesized one at about the beginning of the rhenana zone and a second principal pulse in the late linguiformis zone that encompassed the f f transition developing the veimarn milanovsky scenario of the global extensional pulse it is assumed that the key endogenous factors were related to episodic super plume activity the tectonically triggered changes climaxed in thermal and nutrient pulses and induced the stepdown ecosystem destabilization observed in the f f bio crisis minor cometary strike s might have eventually participated in this prolonged multicausal environmental stress mainly due to additional thermal shocks but perhaps effective on a regional scale only

multi scale depositional successions in tectonic settings observations in sedimentary basins affected by deformation show that the fault induced depositional accommodation at various spatial and temporal scales is closely linked to basin kinematics the tectonically driven sediment infill displays the history of deepening and shoaling facies that are controlled by the activation of faults and changes in their offset rates simply stated this results in shifting sedimentary facies towards the source area or towards the basin centre in response to increasing or decreasing depositional space we propose a first principle conceptual model for tectonic successions controlled by the balance between the rates of creation of depositional space and sediment supply these sediment bodies are bounded by succession boundaries and comprise sourceward or basinward shifting facies tracts that are separated at a point of reversal due to the relatively steep slopes associated with the evolution of faults changes in sediment supply rates and mass wasting are common in these systems and may complicate the normal rhythm of the shifting facies tracts once tectonic quiescence is achieved and if the basin is connected to the open ocean eurybatic or eustatic base level changes may take over and play a greater role in sedimentary rhythm and cyclicity we illustrate the efficacy of the new concept with a review of examples from extensional contractional and strike slip basins we show that the basic tectonic succession model is applicable at all temporal and spatial scales and whether the tectonics cause subsidence or uplift and in all types of tectonic settings that determine the evolution of sedimentary basins

uniform slip rate along the kunlun fault implications for seismic behaviour and large scale tectonics a long term slip rate is derived from concordant 10 be 26 al and 14 c dating of cumulativeoffse ts along much of the length of the kunlun fault values at 6 sites indi cateuniform slip 11 5 2 0 mm yr since 40 kyr bp this relatively high slip rate corresponds to a first order discon tinuity in the asian crustal velocity field m 8a nd m 7 5 earthquakes on 2 segments of the fault recur with charac teristic slip 10 2ma nd 4 4 0 4m ev e ry 850 and 420 yrs respectively

the 40ar 39ar dating of magmatic activity in the donbas fold belt and the scythian platform eastern european craton 1 the donbas fold belt is the compressionally deformed southeasternmost part of the intracratonic late paleozoic dniepr donets rift basin it is situated in an intracratonic setting but close to the southern margin of the east european craton south of which lies the scythian platform a range of igneous rocks from the donbas fold belt and the scythian platform were dated by the 40ar 39ar method in order to constrain the ages of magmatic activity in these areas and compare them the plateau ages from the south margin of the donbas fold belt vary from 151 4 4 7 ma to 278 1 5 3 ma and define three main age groups middle late jurassic middle late triassic and early permian the age spectra obtained from the scythian platform samples are often disturbed as a result of limited alteration the proposed ages plateau and pseudoplateau vary from 174 4 2 1 ma to 243 7 1 4 ma and two major age groups are defined in early carboniferous and triassic jurassic times the early permian 285 270 ma and early triassic 245 250 ma ages of magmatic activity are the same in both areas in the late triassic the ages of magmatic activity are slightly different 220 and 205 ma and they are entirely different thereafter these data can be interpreted as indicating a mantle plume as common deep magmatic source

thermoluminescence dating of sand dunes in rajasthan india we report here a new application of thermoluminescence tl for dating sand dunes this application assumes that exposure to sunlight causes bleaching of the geological tl of a sediment to a residual value and that tl accumulation starts again when the sediment is buried under fresh deposit and is thus shielded from the sun although the tl method has been applied to loess1 2 and ocean sediments3 4 the application of this technique to sand dunes provides the first reliable dating control for dune dynamics palaeoclimatology and spread of deserts

new empirical relationships among magnitude rupture length rupture width rupture area and surface displacement source parameters for historical earthquakes worldwide are compiled to develop a series of empirical relationships among moment magnitude m surface rupture length subsurface rupture length downdip rupture width rupture area and maximum and average displacement per event the resulting data base is a significant update of previous compilations and includes the additional source parameters of seismic moment moment magnitude subsurface rupture length downdip rupture width and average surface displacement each source parameter is classified as reliable or unreliable based on our evaluation of the accuracy of individual values only the reliable source parameters are used in the final analyses in comparing source parameters we note the following trends 1 generally the length of rupture at the surface is equal to 75 of the subsurface rupture length however the ratio of surface rupture length to subsurface rupture length increases with magnitude 2 the average surface displacement per event is about one half the maximum surface displacement per event and 3 the average subsurface displacement on the fault plane is less than the maximum surface displacement but more than the average surface displacement thus for most earthquakes in this data base slip on the fault plane at seismogenic depths is manifested by similar displacements at the surface log linear regressions between earthquake magnitude and surface rupture length subsurface rupture length and rupture area are especially well correlated showing standard deviations of 0 25 to 0 35 magnitude units most relationships are not statistically different at a 95 significance level as a function of the style of faulting thus we consider the regressions for all slip types to be appropriate for most applications regressions between magnitude and displacement magnitude and rupture width and between displacement and rupture length are less well correlated and have larger standard deviation than regressions between magnitude and length or area the large number of data points in most of these regressions and their statistical stability suggest that they are unlikely to change significantly in response to additional data separating the data according to extensional and compressional tectonic environments neither provides statistically different results nor improves the statistical significance of the regressions regressions for cases in which earthquake magnitude is either the independent or the dependent parameter can be used to estimate maximum earthquake magnitudes both for surface faults and for subsurface seismic sources such as blind faults and to estimate the expected surface displacement along a fault for a given size earthquake

global events of the late paleozoic early devonian to middle permian a review abstract the late paleozoic early devonian to middle permian was an interval of profound changes in earth surface systems reflected in dynamic interplay among the biosphere hydrosphere atmosphere and geosphere major events transpired including the colonization of landmasses by vascular plants the assembly of the supercontinent pangea two first order mass extinctions the frasnian famennian and devonian carboniferous boundary events and the most severe icehouse climate mode of the phanerozoic the late paleozoic ice age lpia the goals of the present review are 1 to summarize major global developments in climate oceanography and paleobiology during the late paleozoic 2 to examine the roles of land plant evolution global tectonics and large igneous province magmatism in driving these developments and 3 to serve as an introduction to the 23 contributions to this special issue of palaeogeography palaeoclimatology palaeoecology indicating how they advance our knowledge of various scientific issues related to these developments

morphological dating of cumulative reverse fault scarps examples from the gurvan bogd fault system mongolia summary we relate reverse fault scarp morphology formed by several earthquake dislocations to the average deformation rate using a morphological dating model based on a diffusion analogue of erosion our scarp degradation model includes diffusive erosion during the interseismic period the gravitational collapse of the coseismic fault scarp just after formation and the variation of the surface rupture location interactions between thrusting and geomorphic processes acting on scarp morphology are analysed along the gurvan bogd range in mongolia four main processes acting on scarp morphology were distinguished i gravitational collapse of the frontal scarp resetting the diffusive scarp if fault offsets are big and faulting is localized 2 progressive erosion of the fault scarp during the interseismic period 3 folding associated with the frontal thrust and backthrusts 4 competing alluvial deposition on mountain piedmont slopes and abrasion of the fault scarp by wash processes the growth of cumulative reverse fault scarps is suppressed when they are located in the outwash of major drainage basins they can grow higher in distance from major catchment discharges the modelling suggests that the morphology of the scarp and its apparent degradation stage depend on the parameters controlling the amount of frontal collapse the magnitude of coseismic offsets the dip of the fault near the surface and the step distance between faults folding associated with thrusting creates a convexity on the upper part of the scarp and increases its height the comparison of different scarp profiles suggests that folding leads to an overestimate of the morphological age we estimate a diffusion coefficient at 3 3 1 7 m 2 ka l morphological ages calculated with our model confirm that slip rate along reverse faults of the gurvan bogd range has not been constant over the last 100 ka

the donbas foldbelt its relationships with the uninverted donets segment of the dniepr donets basin ukraine abstract the donbas foldbelt df is a thrust faulted and folded inverted segment of the dniepr donets basin ddb it lies between the scythian and east european platforms north of the black sea and is conventionally thought to have formed in the early permian as part of the late palaeozoic hercynian uralian orogenic frame of cratonic europe the ddb itself formed as a result of late devonian intracratonic rifting and contains a thick up to 22 km late palaeozoic and mesozoic sedimentary succession the deformed strata preserved at the erosional surface of the df are mainly carboniferous the donets segment of the ddb displays mild inversion structures that are transitional to those in the df recently acquired regional seismic reflection data in the donets part of the ddb allow these structures to be imaged in the subsurface for the first time a widespread early permian unconformity occurring throughout the ddb is much more pronounced on its southern margin than on its northern one and appears to be related to profound uplift of the southern flank of the basin and the neighbouring ukrainian shield rather than to crustal shortening faults associated with the early permian unconformity are extensional in style gentle folds and other local structures in the southern flank and axis of the donets segment are mainly located in areas associated with early permian salt movements no significant development of compressional structures of early permian age can be seen in the seismic data where it is available in contrast there is ample evidence of latest cretaceous earliest tertiary compressional deformation in the ddb including the subsurface expression of structures along strike of the main folds of the df a review of geological evidence in the df also indicates that the main period of shortening that can be definitely constrained in time is latest cretaceous earliest tertiary the eastern part of the df records intense late triassic aged cimmerian deformation but none of clearly permian age it is tentatively concluded that the main phases of trans compressional tectonics forming the df were cimmerian and especially alpine rather than hercynian uralian

active normal faulting and crustal extension a world wide review of fault plane solutions and focal depths for large normal faulting earthquakes on the continents shows that the overwhelming majority of such earthquakes nucleate in the depth range 6 15 km on faults dipping between 30 and 60 in the few cases where levelling or seismic data are good enough these normal faults are shown to be approximately planar from the surface to their nucleation depth at the base of the brittle crust there is evidence that in some cases as a result of the enormous transitory increase in strain rate during large earthquakes rupture continues into the normally ductile lower crust on surfaces with substantially gentler dips these low angle surfaces may be analogous to some of the detachments seen in metamorphic core complexes of the western usa but the nature of the motion on them depends on strain rate as well as on rheological contrasts between the detachments and the blocks on either side such contrasts however are unlikely to introduce substantial curvature to an originally planar shear zone if the observed spread in active normal fault dips is caused by rotation of the faults and the blocks they bound during extension then a maximum value of 1 7 can be accommodated by seismic activity on a single generation of normal faults with continued extension either a new generation of steeper faults cutting the rotated first faults is likely to form or the deformation will continue aseismically on faults dipping at less than 30 large earthquakes have not been observed to nucleate on very low angle 20 normal faults within the continental crust anywhere in the world such faults can of course move aseismically but are unlikely to do so on a large scale within the upper crust in areas where steep normal faults are seismically active thus extensional models that require concentrated simple shear on large sub horizontal faults within the brittle upper crust will also require a spatial separation between aseismic very low angle faulting and seismic highangle faulting since seismogenic high angle faults dominate the topography of extending regions upper crustal very low angle faulting if it occurs on a large scale presumably does so in areas that are relatively fiat

planar high angle faulting in the basin and range geodetic analysis of the 1983 borah peak idaho earthquake geodetic elevation changes record the broad scale deformation associated with the m 7 0 october 28 1983 borah peak idaho earthquake on the lost river fault the crest of the lost river range rose 0 2 m and adjacent thousand springs valley subsided 1 0 m in relation to reference points 45 km from the main shock epicenter the deformation was modeled by dislocations in an elastic half space a planar fault with uniform dip slip of 2 05 0 10 m dipping 47 o 2osw and extending to a vertical depth of 13 3 1 2 km fits the geodetic data best and is also consistent with the main shock hypocenter and fault plane solution the geodetic moment is 2 6 0 5 x 1019 n m 2 6 0 5 x 1026 dyn cm and the estimated static stress drop is 2 9 0 4 mpa 29 4 bars tests for coseismic slip on listric faults which flatten with depth and on detachments horizontal faults or shear zones showed fits to the geodetic data that are inferior to those for planar high angle faults no detectable coseismic slip occurred on the mesozoic white knob thrust fault although the low angle thrust sheet intersects the south end of lost river fault near the 1983 mainshock epicenter if the high angle lost river fault abuts a flat lying detachment fault or shear zone such a structure must lie at depths of 12 km near the brittle ductile transition where stick slip behavior gives way to creep the depth and geometry of faulting at borah peak is similar to that inferred from seismic and geodetic evidence for the 1954 m 7 2 fairview peak nevada and the 1959 m 7 3 hebgen lake montana events suggesting that if detachments are active at these localities they are deep and most likely slip by creep

ubiquity of anomalous fading in k feldspars and the measurement and correction for it in optical dating anomalous fading rates were measured in k feldspars separated from 49 sediment samples mainly from north america the intensity of the optically stimulated luminescence was found to decrease linea

prehistoric ruptures of the gurvan bulag fault gobi altay mongolia 1 the 1957 gobi altay m8 3 earthquake in southern mongolia was associated with the simultaneous rupture of several faults including the gurvan bulag reverse fault which is located about 25 km south of the main strike slip bogd fault our study of paleoseismic excavations across the gurvan bulag fault suggests that the penultimate surface rupture occurred after 6 0 ka most likely between 2 6 and 4 4 ka and a possible earlier rupture occurred after 7 3 ka our interpretation of the stratigraphic relations in one of the exposures suggests that at least five earthquakes have generated surface rupture of the gurvan bulag fault since the abandonment of an ancient alluvial fan surface luminescence dating of sediment associated with this surface indicates that it formed either 26 6 2 1 ka or 16 1 2 0 ka these data imply that the recurrence intervals for surface faulting on the gurvan bulag and bogd faults are similar on the order of several thousands of years but that the penultimate surface ruptures of the two faults did not occur during the same earthquake

slip rates along active faults estimated with cosmic ray exposure dates application to the bogd fault gobi altai mongolia dating morphological features displaced along active faults presents a major difficulty in evaluation of slip rates we used in situ produced 10 be to calculate minimum ages for alluvial surfaces misaligned by movement along a major active fault in the gobi altai western mongolia the maximum slip rate of 1 2 mm yr suggested by this method contrasts strongly with rates of 20 mm yr that we estimated by correlation of alluvial deposition with warm humid periods associated with the last glacial termination estimated to have occurred about 12 ka in western tibet the 10 be based slip rate indicates that strong earthquakes can occur along faults with low slip rates and demonstrates the contribution of cosmic ray exposure dating in quaternary tectonic analyses

cosmogenic dating of fluvial terraces fremont river utah absolute dating of river terraces can yield long term incision rates clarify the role of climate in setting times of aggradation and incision and establish the rates of pedogenic processes while surface exposure dating using cosmogenic 10be and 26al would seem to be an ideal dating method the surfaces are composed of individual clasts each with its own complex history of exposure and burial the stochastic nature of burial depth and hence in nuclide production in these clasts during exhumation and fluvial transport and during post depositional stirring results in great variability in clast nuclide concentrations we present a method for dealing with the problem of pre depositional inheritance of cosmogenic nuclides we generate samples by amalgamating many individual clasts in order to average over their widely different exposure histories depth profiles of such amalgamated samples allow us to constrain the mean inheritance to test for the possible importance of stirring and to estimate the age of the surface working with samples from terraces of the fremont river we demonstrate that samples amalgamated from 30 clasts represent well the mean concentration depth profiles show the expected shifted exponential concentration profile that we attribute to the sum of uniform mean inheritance and depth dependent post depositional nuclide production that the depth dependent parts of the profiles are exponential argues against significant post depositional displacement of clasts within the deposit our technique yields 10be age estimates of 60 9 102 16 and 151 24 ka for the three highest terraces corresponding to isotope stages 4 5d and 6 respectively the mean inheritance is similar from terrace to terrace and would correspond to an error of 30 40 ka if not taken into account the inheritance likely reflects primarily the mean exhumation rates in the headwaters of order 30 m ma

dobrefraction 99 velocity model of the crust and upper mantle beneath the donbas foldbelt east ukraine abstract the donbas foldbelt df is the uplifted and deformed part of the up to 20 km thick dniepr donets basin ddb that formed as the result of rifting of the east european craton eec in the late devonian uplift especially of the southern margin of the basin occurred in early permian times in a trans tensional tectonic stress regime while folding and reverse faulting mainly occurred later mainly during the late cretaceous a seismic refraction wide angle reflection survey was carried out in 1999 dobrefraction 99 to complement existing deep seismic sounding dss data from the area that did not record significant pn phase arrivals because of insufficient maximum offset dobrefraction 99 comprised some 245 recording stations along a line of 360 km length with 11 in line shot points as well as a 100 km away parallel 190 km long subsidiary fan profile the main profile runs between the shores of the azov sea in the south to the ukraine russia border in the north across the azov massif ukrainian shield the foldbelt and the voronezh massif particular scientific targets include the nature of the crust mantle transition and the geometry of crustal upper mantle structures related to rifting and subsequent basin inversion tomographic inversion as well as ray trace based velocity modelling has been carried out the velocity signature of the sedimentary basin itself is well resolved indicating an asymmetric form with a steeper basement surface in the south than in the north and a total thickness of about 20 km a thick 10 km high velocity 6 9 km s lower crustal body lies beneath the rift basin itself offset slightly to the north compared to the main basin depocentre likely related to the rifting processes velocities in the crust below the ukrainian shield south of the foldbelt are in general higher than beneath the voronezh massif to the north the moho displays only slight topography around a depth of 40 km along the profile

phanerozoic hot spot traces and paleogeographic reconstructions of the siberian continent based on interaction with the african large low shear velocity province abstract we review intraplate magmatism in siberia and its folded surroundings from 480 ma to the present we describe several large igneous provinces lips and the intervals in which they were continuously formed within the limits of the siberian continent the altay sayan early paleozoic magmatic area 598 446 ma the altay sayan lip 408 393 ma the viluy lip 380 350 ma the barguzin vitim lip 310 275 ma the late paleozoic rift system of central asia 318 242 ma the siberian traps and west siberian rift system 250 249 ma the east mongolian and west trans baikalian lip 228 195 ma and a number of various aged late mesozoic and cenozoic rift zones and magmatic areas from 160 ma to the present day following lawver and muller 1994 kharin 2000 lawver et al 2002 and chernysheva et al 2005 we accept the position of the icelandic hot spot under the siberian trap area at the permo triassic boundary that enables us to estimate the geographic coordinates of the siberian trap location at 250 ma they are the same as iceland today presently the icelandic hot spot is situated above the african large low shear velocity province llsvp that indicates a hot mantle plume we suggest a set of paleogeographic reconstructions of the siberian continent for which we evaluate the paleolatitude based on the paleomagnetic data and estimate the paleolongitude position by placing siberia above the african llsvp furthermore we estimate the geographic coordinates for other ancient hot spots in the framework of the african llsvp that we consider to be responsible for the intraplate magmatism during different time periods in the phanerozoic eon available rare element and isotopic characteristics of the intraplate magmatic rocks of siberia enable us to determine three primary sources moderately depleted mantle prema enriched mantle em i and em ii of the mantle origin magma we propose that the model explains the interaction of the hot mantle plume including hot spots plume tails with the siberian intraplate magmatism areas throughout the phanerozoic eon

postseismic stress transfer explains time clustering of large earthquakes in mongolia abstract three m 8 earthquakes have occurred in mongolia during a 52 year period 1905 1957 since these earthquakes were well separated in space 400 km the coseismic stress change is far too low 0 001 bar to explain mutual earthquake triggering by contrast postseismic relaxation gradually causes a significant stress change 0 1 0 9 bar over large distances using a spring slider model to simulate earthquake interaction we find that viscoelastic stress transfer may be responsible for the earthquake time clustering observed in active tectonic areas therefore revealing postseismic strain by satellite geodesy and modeling earthquake clusters could improve our understanding of earthquake occurrence especially in zones where large earthquakes have already struck in past decades

structural features and evolution of the dniepr donets basin ukraine from regional seismic reflection profiles abstract a set of regional multichannel seismic reflection profiles crossing the dniepr donets dd basin in ukraine 100 200 km long and with a spacing of 10 15 km along strike illuminates the structure of the whole sedimentary cover the rift filled with pre and syn rift devonian sequences and overlain with post rift carboniferous permian mesozoic and palaeogene fill is clearly seen on all sections a basement layer previously identified as a riphean rift succession by refraction seismic studies constitutes in the main strata of the devonian and early carboniferous successions the structure of the rift is characterised by large scale rotational fault blocks and half grabens carried by basin parallel to normal marginal faults or by major horst blocks the total thickness of the devonian and younger succession is up to 19 km in the study area post rift carboniferous and mesozoic sediments cover the rift flanks and increase in thickness towards the rift axis and to the southeast the cumulative thickness of the carboniferous succession alone reaches 11 km with the maximum depth of their base at about 15 km major post rift tectonic events took place at the end of early visean in the middle of serpukhovian in permian times and between the mesozoic and cenozoic tectonic reactivations during carboniferous and early permian times were most pronounced in the southeastern part of the dd basin while they were least pronounced in the northwestern part of the basin merging with the pripyat trough where they are barely observed the most active development of salt structures and stocks corresponds with the periods of tectonic reactivation

transpressional tectonics and stream terraces of the gobi altay mongolia we studied the patterns rates and evolution of fluvial terraces and fault system during the building process of an intracontinental transpressional mountain in the gobi altay mongolia by analyzing incisions and offsets of fluvial terraces and alluvial fans we show that the massif has grown by outward migration of thrust faults through time on the northern flank the present bounding thrust fault began its activity 600 ka ago while a more internal sub parallel fault was still active until 200 100 ka vertical offset of an alluvial fan abandoned 100 ka ago allows an estimate of 0 1 mm yr upper pleistocene holocene uplift rate the morphology of the catchment piedmont system strongly suggests a periodical formation of the alluvial surfaces controlled by the climatic pulses at the beginning of the wet interglacial periods the abandonment of the alluvial terraces lags by several thousand years the abandonment of the alluvial fans showing a diachronous incision propagating upstream the incision rate deduced from the different elevations of straths exceeds of one order of magnitude the rock uplift rate this excess is mostly due to ongoing drainage network growth at the core of the massif and incision due to alluvial apron entrenchment near the outlet this implies that fluvial response is mainly controlled by drainage growth interaction with piedmont and cyclic climatic variations rather than by rock uplift

active intracontinental transpressional mountain building in the mongolian altai defining a new class of orogen abstract mountain ranges that are actively forming around the western and northern perimeter of the indo eurasia collisional deformational field such as the mongolian altai comprise a unique class of intracontinental intraplate transpressional orogen with structural and basinal elements that are distinct from contractional and extensional orogens late cenozoic uplift and mountain building in the mongolian altai is dominated by regional scale dextral strike slip faults that link with thrust and oblique slip faults within a 300 km wide deforming belt sandwiched between the more rigid junggar basin block and hangay precambrian craton dominant orogenic elements in the mongolian altai include double restraining bends terminal restraining bends partial restraining bends single thrust ridges thrust ridges linked by strike slip faults and triangular block uplifts in areas of conjugate strike slip faults the overall pattern is similar to a regional strike slip duplex array however the significant amount of contractional and oblique slip displacement within the range and large number of historical oblique slip seismic events renders the term transpressional duplex more accurate intramontane and range flanking basins can be classified as ramp basins half ramp basins open sided thrust basins pull apart basins and strike slip basins neither a classic fold and thrust orogenic wedge geometry nor a bounding foredeep exists the manner in which upper crustal transpressional deformation is balanced in the lower crust is unknown however crustal thickening by lower crustal inflation and northward outflow of lower crustal material are consistent with existing geological and geodetic data and could account for late cenozoic regional epeirogenic uplift in the russian altai and sayan regions

infra red stimulated luminescence dating of holocene reworked silty sediments abstract infra red stimulated luminescence irsl ages are reported for holocene colluvial lacustrine and alluvial sediments and late glacial loess for colluvial sediments irsl ages concur with independent ages age overestimation occur in the case of very poorly bleached sediments such as young less than 2000 years floodloams for which a high suspended sediment load was deduced from sedimentation rates and actually observed floods age underestimates are observed for late glacial loess probably due to inadequate preheat procedures

the mechanics of continental extension and sedimentary basin formation a simple shear pure shear flexural cantilever model abstract deep seismic reflection data and earthquake seismology show the fundamental importance of major crustal faults during extension of continental lithosphere controlling the development of rifted sedimentary basins major basement faults are generally planar and extend down to 10 15 km depth corresponding to the base of the seismogenic layer beneath this depth deformation gives way to distributed ductile shear in the lower crust and lithospheric mantle a mathematical model is described of the geometric thermal and flexural isostatic response of the lithosphere to extension by planar faulting of the upper crust and plastic distributed deformation in the lower crust and mantle during faulting upper crustal footwall and hanging wall blocks behave as two mutually self supporting flexural cantilevers their response to isostatic forces induced by extension generates footwall uplift and hanging wall collapse for extension on multiple faults interference of footwall uplift and hanging wall collapse gives rise to the familiar block rotations of rift tectonics the flexural cantilever model is able to predict crustal structure and sedimentary basin geometry for faults of arbitrary spacing horizontal displacement and polarity the effects of fault spacing fault polarity and the amount of extension as well as erosion of footwall uplift on crustal structure and basin geometry during both syn rift and post rift stages of basin evolution are explored models of passive rifting involving lithosphere extension in response to the build up of far field tectonic forces and decompression induced partial melting of the upper asthenosphere and lower lithosphere appear to conform to the main geological observations the role of active rifting driven by locally derived deviatoric tensional forces generated by mantle plumes remains uncertain

cosmocalc an excel add in for cosmogenic nuclide calculations as dating methods using terrestrial cosmogenic nuclides tcn become more popular the need arises for a general purpose and easy to use data reduction software the cosmocalc excel add in calculates tcn production rate scaling factors using lal stone dunai and desilets methods topographic snow and self shielding factors and exposure ages erosion rates and burial ages and visualizes the results on banana style plots it uses an internally consistent tcn production equation that is based on the quadruple exponential approach of granger and smith 2000 cosmocalc was designed to be as user friendly as possible although the user interface is extremely simple the program is also very flexible and nearly all default parameter values can be changed to facilitate the comparison of different scaling factors a set of converter tools is provided allowing the user to easily convert cut off rigidities to magnetic inclinations elevations to atmospheric depths and so forth because it is important to use a consistent set of scaling factors for the sample measurements and the production rate calibration sites cosmocalc defines the production rates implicitly as a function of the original tcn concentrations of the calibration site the program is best suited for be 10 al 26 he 3 and ne 21 calculations although basic functionality for cl 36 and c 14 is also provided cosmocalc can be downloaded along with a set of test data from http cosmocalc googlepages com

continental rift development in precambrian and phanerozoic europe europrobe and the dnieper donets rift and polish trough basins abstract upper crustal structure and lower crustal and mantle character of the european continental lithosphere differ significantly from west to east the processes of rifting of phanerozoic western europe s hotter thinner crust compared with the more stable thicker 45 vs 30 km proterozoic crust of the east european craton is being investigated by europrobe case studies of western and eastern european sedimentary basins the dnieper donets basin transects the southwestern part of the east european platform in a nw se direction lying between the ukrainian shield and the voronezh massif rifting took place from early frasnian until perhaps the late visean and was accompanied by major volcanic activity the distribution of both was affected by pre existing basement fault systems the syn and post rift sedimentary succession may be as thick as 20 km in the donets trough basin evolution and the present crustal geometry have been much affected by inversion during the permian in association with uralian orogenesis tectonic events of bathonian oxfordian 168 154 ma and turonian santonian 91 84 ma age are also recorded in the basin stratigraphy the polish trough lies along the boundary between the phanerozoic and proterozoic european crustal domains coincident with the trans european suture zone the presence of this rheological boundary may be paramount in structurally controlling the position of the trough tectonic subsidence analysis indicates an initial late rotliegendes early triassic syn rift phase of development subsequently episodes of increased tectonic subsidence rate occurred during the oxfordian tithonian 157 146 ma and beginning in the cenomanian 95 90 ma the oxfordian tithonian episode is likely the signature of a second extensional event correlated with intensification of rifting within the arctic north atlantic rift system while the cenomanian and later is a precursor to mild compressional intraplate orogenic movements present day crustal structure reflects the docking of phanerozoic crust against the proterozoic during palaeozoic orogenies permo carboniferous wrenching and transtensional modifications leading to formation of the polish trough as well as modifications during the late cretaceous early tertiary inversion process

magmatism and the geodynamics of rifting of the pripyat dnieper donets rift east european platform abstract the distribution of volcanism in the late devonian pripyat dnieper donets rift within the east european platform based upon the results of deep drilling indicates that pre existing basement structures and the major rift bounding faults played an important role in channelling the magmas towards the surface major and trace element and sr nd isotopic studies of the most primitive basic and ultrabasic magmas combined with estimates of the amount of extension 1 1 to 1 3 strongly suggest that magmatism was triggered by the upwelling of a thermally and geochemically anomalous mantle plume from the deep mantle during the late frasnian the peak of the magmatism occurred in the famennian coincident with the maximum amount of lithospheric extension magmatism rifting and domal basement uplife were contemporaneous at several localities within the eep suggesting that the thermal and geodynamic evolution of the platform could have been influenced by a cluster of mantle plumes during the late devonian

paleoseismic evidence of characteristic slip on the western segment of the north anatolian fault turkey we have conducted a paleoseismic investigation of serial fault rupture at one site along the 110 km rupture of the north anatolian fault that produced the mw 7 4 earthquake of 17 august 1999 the benefit of using a recent rupture to compare serial ruptures lies in the fact that the location magnitude and slip vector of the most recent event are all very well documented we wished to determine whether or not the previous few ruptures of the fault were similar to the recent one we chose a site at a step over between two major strike slip traces where the principal fault is a normal fault our two excavations across the 1999 rupture reveal fluvial sands and gravels with two colluvial wedges related to previous earthquakes each wedge is about 0 8 m thick considering the processes of collapse and subsequent diffusion that are responsible for the formation of a colluvial wedge we suggest that the two paleoscarps were similar in height to the 1999 scarp this similarity supports the concept of characteristic slip at least for this location along the fault accelerator mass spectrometry ams radiocarbon dates of 16 charcoal samples are consistent with the interpretation that these two paleoscarps formed during large historical events in 1509 and 1719 if this is correct the most recent three ruptures at the site have occurred at 210 and 280 year intervals

luminescence dating of loess from the northwest united states thermoluminescence tl and infra red stimulated luminescence irsl ages have been determined for loess from the columbia plateau region of southeast washington and northeast oregon u s a the irsl ed values and ages appear to be tending towards a maximum level lower than that of the tl ed values and ages in general the tl ages are in stratigraphic order and agree well with the age control in the form of 14c and tl dated tephra units derived from various eruptions of mount st helens

zeolites in petroleum and natural gas reservoirs zeolites have been reported in petroleum and natural gas reservoirs of a wide range of geological ages from many parts of the world such zeolite bearing oil and gas reservoirs are not comparatively large in number and scale however where present in petroleum and natural gas reservoirs zeolites can have profound effects on the quality of the reservoirs affecting rock porosity and permeability zeolite containing reservoir rocks vary widely lithologically including not only porous pelitic sedimentary rocks but also volcanogenic rocks and even fractured intrusive and plutonic rocks several different genetic types of zeolite occurrences have been distinguished and classified e g hay 1966 1986 1995 iijima 1980 1986 as hay and sheppard discussed and summarized in an earlier chapter this volume in addition the organic origin theory for the formation of economic oil and gas resources seems to have been universally accepted including the prominent kerogen decomposition theory summarized by tissot and welte 1978 sedimentary basins filled by very thick sequences of sedimentary strata containing organic rich source rocks and porous reservoir rocks are considered necessary for producing hydrocarbon resources such sedimentary basins develop primarily through rifting or in relation to arc formation at active plate boundaries and they are often accompanied by heating and extensive volcanic activity most types of zeolite occurrence are consequently constrained to burial diagenesis uplift related late stage diagenesis surdam and boles 1979 boles 1993 and hydrothermal alteration as will be discussed in this chapter zeolites in hydrocarbon reservoir rocks occur commonly as cements and grain replacements in the form of disseminated microcrystalline aggregates and occasionally as macroscopic crystals in vugs and veins it was in 1950s that coombs and co workers pioneered the petrologic study of rock forming zeolites through their classic research on burial metamorphism of the triassic geosynclinal deposits in south syncline new

rapid slip along the central altyn tagh fault morphochronologic evidence from cherchen he and sulamu tagh consistent with the d 18 o record from the guliya ice cap in the west kunlun the features of interest were all formed by glacial and fluvial processes subsequent to marine isotope stage 5e with the youngest features having formed during the early holocene optimum this near field morphochronological slip rate is averaged over many earthquake cycles and is hence little affected by interseismic strain it is kinematically consistent with other somewhat lower geomorphic slip rate measurements to the east the average rate and lower bounds obtained from alternate interpretational models 18 4 mm yr cannot be reconciled with the most rece geodetic measurements 7 mm yr suggesting that interseismic strain and interactions with adjacent faults may lead to disparate geologic and geodetic rate estimates this late pleistocene holocene morphochronologic rate would imply that at this longitude the altyn tagh fault on the north edge of tibet might absorb almost as much of india s convergence relative to siberia as the himalayan main frontal thrust does on the southern edge of the plateau index terms 1035 geochemistry geochronology 1208 geodesy and gravity crustal movements intraplate 8110 8102 tectonophysics continental contractional orogenic belts 8107 tectonophysics continental neotectonics keywords slip rates cosmogenic dating indo asian collision

hydrocarbon habitat of the dniepr donets depression abstract basin inversion depending on its intensity can enhance the trapping potential of a basin or causes destruction of major hydrocarbon resources post inversion subsidence depending on its magnitude and the amount of syn inversion erosion can induce a second phase of hydrocarbon generation and the charging of inversion structures however this mechanism which contributed for instance to the hydrocarbon habitat of inverted basins in the southern north sea was not effective in the dniepr donets basin the dniepr donets depression forms part of the pripyat dniepr donets donbass karpinsky aulacogen that evolved as a devonian rift the post rift subsidence of this basin was interrupted during the late early permian when its southeastern parts were partly inverted further inversion pulses straddle the jurassic cretaceous and the cretaceous tertiary boundaries the dniepr donets depression hosts the most important hydrocarbon province of the ukraine at the beginning of 1994 ultimate recoverable reserves in established accumulations past production and remaining reserves amounted to about 170 10 6 t of oil and gas condensate and 980 10 9 m 3 gas the bulk of oil and gas accumulations is contained in carboniferous to early permian postrift series source rocks occur in devonian syn rift and carboniferous post rift series these attained maturity prior to basin inversion hydrocarbon accumulations are characterized by multiple reservoir seal pairs the mature syn rift devonian and the immature post inversion series contain only minor hydrocarbon accumulations oil and gas accumulations are mainly trapped in syn rift salt induced and inversion related structures the latter received their hydrocarbon charge mainly due to inversion induced destruction of pre existing accumulations and ensuing re migration of hydrocarbons

numerical modelling of the thermal evolution of the northwestern dniepr donets basin ukraine abstract the dniepr donets basin ddb is a late devonian rift structure located within the east european craton numerical heat flow models for 13 wells calibrated with new maturity data were used to evaluate temporal and lateral heat flow variations in the northwestern part of the basin the numerical models suggest that heat flow was relatively high during late carboniferous and or permian times the relatively high heat flow is probably related to an early permian re activation of tectonic activity reconstructed early permian heat flow values along the axial zone of the rift are about 60 mw m2 and increase to 90 mw m2 along the northern basin margin these values are higher than those expected from tectonic models considering a single late devonian rifting phase the calibration data are not sensitive to variations in the devonian carboniferous heat flow therefore the models do not allow deciding whether heat flows remained high after the devonian rifting or whether the reconstructed permian heat flows represent a separate heating event analysis of the vitrinite reflectance data suggest that the northeastern dniepr donets basin is characterised by a low mesozoic heat flow 30 35 mw m2 whereas the present day heat flow is about 45 mw m2

clay mineral assemblages and analcime formation in a palaeogene fluvial lacustrine sequence maiz gordo formation palaeogen from northwestern argentina abstract the palaeogene maiz gordo formation is one of the main lacustrine events recorded in northwestern argentina it consists of sandstone mudstone and limestone beds 200 m thick deposited in a brackish alkaline lake and braided alluvial systems the maiz gordo lake evolved mainly as a closed system with brief periods as an open one x ray diffraction xrd and scanning electron microscopy sem were used to study samples from seven sites corresponding respectively to proximal intermediate and transitional positions of the fluvial environment and marginal and inner lake environment focusing on the clay mineralogy and analcime formation the basinward zonation of diagenetic minerals identified in the maiz gordo lake was mordenite analcime k feldspar although not a typical zonation of saline alkaline lakes it does indicate an increase in salinity and alkalinity towards the centre in proximal fluvial settings smectite predominates at the base of the sequence with scarce kaolinite towards the top a striking increase in kaolinite content suggests a change from a relatively arid climate with alternating humid and dry seasons towards a warm and humid climate kaolinite content clearly decreases in a basinward direction such a variation is attributable to changes in hydro geochemistry denoting the progressive influence of the brackish and alkaline lake water on interstitial pores sem images of intermediate fluvial samples reveal authigenesis of illite at the expense of kaolinite booklets in littoral and inner lake settings the clay fraction is composed of muscovite sometimes with subordinate smectite analcime occurs in variable amounts in all sedimentary facies in rock pores or filling veins it forms subhedral square to hexagonal or anhedral rounded crystals denoting that they coarsened at low to moderate degrees of supersaturation although the mordenite identified in a fluvial level would have been the precursor of analcime in the maiz gordo basin no textural evidence of analcime formation through replacement of mordenite or other precursor zeolite was found hence it is more probable that analcime formation took place by direct authigenic precipitation or through the reaction between interstitial brines and clay minerals or plagioclase

plate tectonics and basin subsidence history tectonic setting exerts fi rst order control on basin formation as refl ected in basin subsidence history while our approach ignores the effects of fl exural loading and eustatic sea level change consistency of backstripped subsidence histories i e with local loading effects of sediment removed suggests consistent tectonic driving mechanisms in each tectonic setting with the possible exception of forearc basins based on published subsidence curves and open fi le stratigraphic data we show the subsidence characteristics of passive margins strike slip basins intracontinental basins foreland basins and forearc basins passive margin subsidence is characterized by two stages rapid initial synrift subsidence and slow post rift thermal subsidence with increasing subsidence rates toward the adjacent ocean basin subsidence of intracontinental basins is similar in magnitude to that seen in passive margin settings but the former is generally slower longer lived and lacks initial subsidence long lived subsidence for many intracontinental basins is consistent with cooling following thermal perturbation of thick lithosphere found beneath old parts of continents basins associated with strike slip faults are usually short lived with very rapid subsidence changes in local stress regimes as strike slip faults evolve and migrate over time coupled with three dimensional heat loss in these small basins likely explain this subsidence pattern foreland basin subsidence rates refl ect the fl exural response to episodic thrust loading resultant subsidence curves are punctuated by convex up accelerating segments forearc basins have the least consistent subsidence patterns subsidence histories of these basins are complex and may refl ect multiple driving mechanisms of subsidence in forearc settings second order deviations in subsidence suggest reactivation or superimposed tectonic events in many basin settings the effects of eustatic sea level change may also explain some deviations in curves for many of these settings subsidence histories are suffi ciently distinctive to be used to help determine tectonic setting of ancient basin deposits

riser diachroneity lateral erosion and uncertainty in rates of strike slip faulting a case study from tuzidun along the altyn tagh fault nw china 1 at late quaternary timescales offset fluvial terrace risers are among the most common landforms used to determine rates of strike slip faulting although diachroneity in the age of riser segments on opposite sides of the fault has been noted previously an unexplored source of uncertainty associated with deriving slip rates from these markers centers on quantifying the size of the displacement uncertainty such diachroneity introduces to evaluate the impact of riser diachroneity we investigated the tuzidun site 37 73 n 86 72 e along the cherchen he reach of the active central altyn tagh fault the east bank of the channel is flanked by a left laterally offset terrace riser while the measured offset is 54 3 m geochronologic measurements and analysis of riser topography indicate that the downstream riser segment formed between 6 0 0 8 ka and 5 7 0 4 ka while the upstream riser segment may have been laterally refreshed as recently as 0 5 0 2 ka a valley wall on the west bank of the channel places a maximum limit of 38 6 m on the amount of possible lateral erosion of the upstream riser this bound in turn limits the total offset since formation of the downstream riser to range from 54 3 to 89 7 m together these observations bracket the millennial altyn tagh fault slip rate to range from 9 0 1 3 to 15 5 1 7 mm a 1 more generally this investigation shows that the observed riser displacement does not necessarily correlate with the age of either riser segment downstream or upstream of the fault in cases where one segment is displaced while the other is subjected to lateral erosion if this diachroneity goes undetected erroneous slip rate measurements are likely to result

geomorphological investigations and luminescence dating in the southern part of the khangay and the valley of the gobi lakes central mongolia geomorphological investigations in the catchment area of the baydragiyn river along the southern slope of the khangay and in the valley of the gobi lakes in western mongolia provide evidence for late quaternary glaciations and lake level changes thermoluminescence tl and infrared optically stimulated luminescence irsl dating of aeolian and colluvial sediments from the central khangay place the sediments that overlie fluvial and glaciofluvial terraces in the holocene an age of 21 ka is determined for a sand deposit overlying the terrace that is related to the last glacial ice margin lacustrine sediments from higher beach lines in the valley of the gobi lakes provide evidence for a slightly more humid period around 1 5 ka and a larger extent of the lakes in the early holocene at about 8 5 ka as also reported from other parts of central asia remnants of lacustrine sediments buried by alluvial gravel and indicating a huge palaeolake in the basin of the orog nuur however date to the early stage of the last glaciation around 70 ka copyright 2001 john wiley sons ltd

thermogenetic degradation of early zeolite cement an important process for generating anomalously high porosity and permeability in deeply buried sandstone reservoirs abstract diagenetic explanations to anomalously high porosities and permeabilities in deeply buried sandstones have been presented for many reservoirs for example grain coatings of microquartz or chlorite can preserve porosity by preventing succeeding quartz overgrowths and dissolution of grains or cement can generate secondary porosity anomalously high porosity and permeability up to 25 and 500 md respectively characterize the deeply buried 5 km upper jurassic shoreface sandstones of the gert member heno formation in the hejre field in the danish central graben optical cathodoluminescence and scanning electron microscopy were used to characterize the petrography and diagenetic changes that resulted in this high pressure and high temperature hpht reservoir this was supplemented by chemical analyses icp oes and icp ms mineralogical composition xrd and oxygen isotope composition of quartz and calcite cement sims the petrographic investigation shows that none of the known explanations for anomalously high porosity and permeability can be applied hence a new hypothesis for deeply buried sandstones in contact with lavas and volcaniclastic lithologies is proposed the new hypothesis includes reducing mechanical compaction due to early patchy zeolite cement which was sourced from adjacent lavas and volcaniclastic rocks locally stylolites developed where zeolite cement was less effective hence the present overpressure formed at a later stage increased temperatures during burial resulted in thermal instability of the zeolite cement which was dissolved and authigenic k feldspar and quartz precipitated instead this resulted in a reduction of the cement volume of up to 70 if the zeolite was k heulandite and a corresponding relative porosity increase thus a reduction in cement volume was generated by replacing zeolite of an open crystal structure with mineral phases k feldspar and quartz of denser crystal structures the thermogenetic breakdown of zeolite was forced by increased temperatures during burial this process may explain previously enigmatic highly porous and permeable deeply buried sandstone reservoirs

uplift age and rates of the gurvan bogd system gobi altay by apatite fission track analysis abstract the dating of the uplift onset of the mongolian mountain ranges the northernmost relief associated with the india eurasia convergence is a fundamental issue to better understand the mechanisms of propagation of the cenozoic transpressive deformation in central asia using apatite fission tracks we determined the timing and strain rates of the tectonics affecting the gurvan bogd system in the gobi altay since the middle mesozoic to the late cenozoic the region was firstly affected by a lower middle jurassic tectonic phase characterized by a vertical crustal movement larger than 2 km then followed a protracted period without major crustal vertical movements until the last uplift phase the peneplanation of the jurassic relief produced an erosional surface that has undergone negligible denudation or sedimentation for more than 100 ma this same surface corresponds to the present summit plateaux of the massifs standing about 2000 m above the surrounding region which corresponds to the vertical movement produced by the ongoing uplift modelling of fission track data from the massifs of ih bogd and baga bogd shows that this uplift phase probably started at 5 3 ma the gobi altay mountain range appears therefore as one of the youngest mountain ranges in central asia which is consistent with the idea of a northward propagation of the transpressional deformation from the himalayan front to the siberian craton the cenozoic uplift rate of the massifs is estimated to be between 0 25 and 1 mm yr which is slightly higher than the upper pleistocene vertical slip rates of the bordering faults this suggests that thrust faults observed within the massifs would increase the uplift rate inside the massifs compared to the uplift rate determined at their boundaries

slip rate and slip magnitudes of past earthquakes along the bogd left lateral strike slip fault mongolia we carried out morphotectonic studies along the left lateral strike slip bogd fault the principal structure involved in the gobi altay earthquake of 1957 december 4 published magnitudes range from 7 8 to 8 3 the bogd fault is 260 km long and can be subdivided into five main geometric segments based on variation in strike direction west to east these segments are respectively the west ih bogd wib the north ih bogd nib the west ih bogd wib the west baga bogd wbb and the east baga bogd ebb segments morphological analysis of offset streams ridges and alluvial fans particularly well preserved in the arid environment of the gobi region allows evaluation of late quaternary slip rates along the different faults segments in this paper we measure slip rates over the past 200 ka at four sites distributed across the three western segments of the bogd fault our results show that the left lateral slip rate is similar to 1 mm yr 1 along the wib and eib segments and similar to 0 5 mm yr 1 along the nib segment these variations are consistent with the restraining bend geometry of the bogd fault our study also provides additional estimates of the horizontal offset associated with the 1957 earthquake along the western part of the bogd rupture complementing previously published studies we show that the mean horizontal offset associated with the 1957 earthquake decreases progressively from 5 2 m in the west to 2 0 m in the east reflecting the progressive change of kinematic style from pure left lateral strike slip faulting to left lateral reverse faulting along the three western segments we measure cumulative displacements that are multiples of the 1957 coseismic offset which may be consistent with a characteristic slip moreover using these data we re estimate the moment magnitude of the gobi altay earthquake at m w 7 78 7 95 combining our slip rate estimates and the slip distribution per event we also determined a mean recurrence interval of similar to 2500 5200 yr for past earthquakes along the different segments of the western bogd fault this suggests that the three western segments of the bogd fault and the gurvan bulag thrust fault a reverse fault bounding the southern side of the ih bogd range that ruptured during the 1957 earthquake have similar average recurrence times and therefore may have ruptured together in previous earthquakes as they did in 1957 these results suggest that the western part of the bogd fault system including the gurvan bulag thrust fault usually behaves in a characteristic earthquake mode

fault behavior and characteristic earthquakes examples from the wasatch and san andreas fault zones paleoseismological data for the wasatch and san andreas fault zones have led to the formulation of the characteristic earthquake model which postulates that individual faults and fault segments tend to generate essentially same size or characteristic earthquakes having a relatively narrow range of magnitudes near the maximum analysis of scarp derived colluvium in trench exposures across the wasatch fault provides estimates of the timing and displacement associated with individual surface faulting earthquakes at all of the sites studied the displacement per event has been consistently large measured values range from 1 6 to 2 6 m and the average is about 2 m on the basis of variability in the timing of individual events as well as changes in scarp morphology and fault geometry six major segments are recognized along the wasatch fault on the basis of the most likely number of surface faulting events 18 that have occurred on segments of the wasatch fault zone during the past 8000 years an average recurrence interval of 400 666 years with a preferred average of 444 years is calculated for the entire zone geologic data on the distribution of slip associated with prehistoric earthquakes and slip rates along the south central segment of the san andreas fault suggest that the m 8 1857 earthquake is a characteristic earthquake for this segment comparisons of earthquake recurrence relationships on both the wasatch and san andreas faults based on historical seismicity data and geologic data show that a linear constant b value extrapolation of the cumulative recurrence curve from the smaller magnitudes leads to gross underestimates of the frequency of occurrence of the large or characteristic earthquakes only by assuming a low b value in the moderate magnitude range can the seismicity data on small earthquakes be reconciled with geologic data on large earthquakes the characteristic earthquake appears to be a fundamental aspect of the behavior of the wasatch and san andreas faults and may apply to many other faults as well

constraints on the viscosity of the continental crust and mantle from gps measurements and postseismic deformation models in western mongolia 1 we use gps measurements and models of postseismic deformation caused by seven m6 8 to 8 4 earthquakes that occurred in the past 100 years in mongolia to assess the viscosity of the lower crust and upper mantle we find an upper mantle viscosity between 1 1018 and 4 1018 pa s the presence of such a weak mantle is consistent with results from independent seismological and petrological studies that show an abnormally hot upper mantle beneath mongolia the viscosity of the lower crust is less well constrained but a weak lower crust 3 1016 to 2 1017 pa s is preferred by the data using our best fit upper mantle and lower crust viscosities we find that the postseismic effects of viscoelastic relaxation on present day horizontal gps velocities are small 2 mm yr 1 but still persist 100 years after the 1905 m8 4 bolnay earthquake this study shows that the gps velocity field in the baikal mongolia area can be modeled as the sum of 1 a rigid translation and rotation of the whole network 2 a 3 5 mm yr 1 simple shear velocity gradient between the siberian platform to the north and northern china to the south and 3 the contribution of postseismic deformation mostly caused by the 1905 bolnay tsetserleg sequence and by the smaller but more recent 1957 bogd earthquake

paleostress field reconstruction and revised tectonic history of the donbas fold and thrust belt ukraine and russia 1 in the wnw ese donbas fold belt df inversion of 3500 microtectonic data collected at 135 sites in proterozoic devonian carboniferous and cretaceous competent rocks allowed reconstruction of 123 local stress states accordingly four successive paleostress fields reveal the tectonic evolution of the df at the numerous sites that have been affected by polyphase tectonics the chronology between local paleostress states also paleostress fields was established using classical criteria crosscutting striae pre or post folding stress states stratigraphic control the oldest event is an extensional stress field with nne ssw 3 it corresponds to the rifting phases that generated the basin in devonian times and its early visean reactivation later the df was affected by a transtension with nw se 3 characterizing early permian tectonism including the development of the main anticline of the df and the pronounced uplift of its southern margin and ukrainian shield two paleostress fields characterize the cretaceous paleocene inversion of the df which was accompanied by folding and thrusting both are compressional in type but differ by the trend of 1 which was first nw se and subsequently n s the discrete paleostress history of the df allows a revised interpretation of its tectonic evolution with significant implications for understanding the geodynamic evolution of the southern margin of the east european craton

structures associated with inversion of the donbas foldbelt ukraine and russia abstract the donbas foldbelt is part of the prypiat dnieper donets intracratonic rift basin belarus ukraine southern russia that developed in late devonian times and was reactivated in early carboniferous to the southeast the donbas foldbelt joins the contiguous deformed karpinsky swell basin inversions led first to the uplift of the palaeozoic series mainly carboniferous but also syn rift devonian strata in the southwesternmost part of the donbas foldbelt which are deeply buried in the other parts of the rift system and later to the formation of the fold and thrust belt the general structural trend of the donbas foldbelt formed mainly during rifting is wnw ese this is the strike of the main rift related fault zones and also of the close to tight main anticline of the donbas foldbelt that developed along the previous rift axis the main anticline is structurally unique in the donbas foldbelt and its formation was initiated in permian times during a period of trans tensional reactivation during which active salt movements occurred a relief inversion of the basin also took place at this time with a pronounced uplift of the southern margin of the basin and the adjacent ukrainian shield subsequently cimmerian and alpine phases of tectonic inversion of the donbas foldbelt led to the development of flat and shallow thrusts commonly associated with folds into the basin a fan shaped deformation pattern is recognised in the field with south to southeast vergent compressive structures south of the main anticline and north to northwest vergent ones north of it these compressive structures are clearly superimposed onto the wnw ese structural grain of the initial rift basin shortening structures that characterise the tectonic inversion of the basin are regionally orientated nw se and n s because of the obliquity of the compressive trends relative to the wnw ese strike of inherited structures major preexisting normal faults and the main anticline in addition to reverse displacements right lateral movements occurred along the main boundary fault zones and along the faulted hinge of the main anticline the existence of preexisting structures is also thought to be responsible for local deviations in contractional trends that are e w in the southwesternmost part of the basin

faulting associated with large earthquakes and the average rate of deformation in central and eastern asia we determine approximate average rates of deformation in portions of eastern and central asia for the last 80 years these rates are based on estimates of source dimensions average displacements seismic moments and orientations of faults of all large earthquakes m 7 5 and as many other major earthquakes m 7 0 as possible in asia since 1900 a major part of this study is the compilation of these data for separate parts of asia we combine seismic moment tensors to estimate the average rotational strain or deformation tensors for these regions for the last 80 years we estimate that shortening across the tien shan has occurred at 11 mm yr between 5 and 19 mm yr left lateral shear on easterly trending planes in mongolia in northwestern tibet gansu and ningxia and on the xianshuihe fault in western sichuan has been very rapid more than 10 mm yr in each region and apparently as rapid as 40 mm yr in northwestern tibet gansu and ningxia slower rates of a few to 10 mm yr appear to characterize east west extension and conjugate north south shortening of tibet the earthquake history of the himalaya is consistent with rates of underthrusting of more than 10 mm yr but is probably less than the convergence rate of india with eurasia of about 50 mm yr the overall strain field is consistent with a large part of india s penetration into eurasia being absorbed by the extrusion of material out of india s way as a result southeast china moved at about 21 mm yr east southeast with respect to eurasia in the last 80 years with an uncertainty of about a factor of 2 in this estimated rate

palaeomagnetism of east siberian traps and kimberlites two new poles and palaeogeographic reconstructions at about 360 and 250 ma summary we studied basalt sills and dykes and kimberlite pipes from the eastern part of the siberian platform these are spread out over a few hundred kilometres and are divided into two age groups late permian early triassic mir aikhal and olenyek regions and late devonian early carboniferous viluy and markha basins aikhal region the palaeomagnetic poles determined for each sill or dyke are statistically different from each other but averaging all corresponding directions from these sills and dykes with those from kimberlites of different generations yields results with acceptable statistics this is probably due to the averaging out of secular variation and or changes in magnetic polarity the resulting palaeomagnetic poles allow one to reconstruct the palaeopositions of siberia during the two large flood basalt events at about 360 and 250 ma a significant rotation of the siberian platform during the devonian and carboniferous is suggested the new data are in general agreement with some earlier palaeomagnetic poles for the late permian early triassic traps of the tungusska basin and significantly reduce uncertainties for previous late devonian early carboniferous siberian poles which were very scattered together with geological and absolute age data the palaeomagnetic data support the hypothesis that kimberlite magmatism and trap intrusions were both rapid and relatively close in time the 360 ma event is emerging as a magmatic event with considerable extent over the russian and siberian platforms related to incipient continental break up and triple junction formation possibly at or near the time of the frasnian famennian mass extinction

diagenetic transformation of clinoptilolite to analcime in silicic tuffs of hokkaido japan diagenetic clinoptilolite and analcime are present in the diagenesis of tertiary marine silicic tuffs in the miti toyokoro borehole hokkaido japan chemical analysis sem and petrographic observations show the mechanism of clinoptilolite to analcime transformation na k clinoptilolite na k 6 4 an alteration product of volcanic glass is detected at depths of 1230 to 2710m a more na rich clinoptilolite na k 9 1 discovered at depths between 2590 and 2710 m is a result of a cation exchange mechanism the formation of analcime at greater depths is due to a microdissolution precipitation mechanism that is na rich clinoptilolite dissolved and analcime precipitated as a result of increasing burial at 2710 m analcime occurs next to the na rich clinoptilolite and it is assumed that the na rich clinoptilolite is an intermediate phase

forebergs flower structures and the development of large intra continental strike slip faults the gurvan bogd fault system in mongolia the gurvan bogd mountains of the gobi altay mongolia contain a system of strike slip faults with a reverse component part of which moved in a large earthquake mw 8 0 in 1957 adjacent and sub parallel to the main ranges are numerous thrust related folds thrust faults and elongated low ridges forebergs all of which result from the shortening component on the fault zone the appearance of these thrust related structures is varied depending on their stage of development preservation and exposure evidence from geomorphology and surface ruptures suggests that they may all serve a common function which is to broaden the deforming zone by creating new structures that are able to accommodate both the strike slip and the shortening components of motion the geomorphology further suggests that these new structures then evolve by lateral propagation and increase in amplitude to eventually merge and form through going new faults subparallel to the old in their early stages the new faults and related structures appear to be influenced by the underlying sediments adjacent to the main range which may include weak layers such as lake beds that can ultimately cause the collapse of foreberg ridges in landslides the migration of faulting away from the main range is likely to be driven by stresses associated with topography which in turn is a consequence of the shortening component the evolution described here is thus peculiar to strike slip faults with a reverse component and can form many of the features of the flower structures that are often described in such oblique shortening zones although the shortening component is often localized in restraining bends its origin may ultimately be related to rotations about vertical axes which are common in deforming continental regions

new 40ar 39ar and k ar ages of the viluy traps eastern siberia further evidence for a relationship with the frasnian famennian mass extinction abstract we present here new ages combining both k ar and 40 ar 39 ar techniques reinforcing the possible link between the viluy traps eastern siberia with the late devonian mass extinctions the viluy traps also referred to as the yakutsk large igneous province are associated with the breakup of the eastern margin of the siberian platform as a triple junction rift system with volcanic outcropping along the lena markha and viluy rivers and an initial volume of volcanic products of about one million cubic kilometers k ar ages obtained on seven samples from the viluy rift display values ranging from 366 5 to 381 5 ma with a mean age of 374 5 ma our new 40 ar 39 ar results display well defined step heating plateau ages ranging from 362 3 3 4 to 379 7 3 5 ma although most k ar and 40 ar 39 ar ages agree within about 1 uncertainty which reinforces the validity of the k ar ages obtained with the cassignol and gillot unspiked technique even in the paleozoic a slightly clearer scenario appears when only the 40 ar 39 ar ages are considered effectively they cluster in two different groups with weighted mean ages of 364 4 1 7 and 376 7 1 7 ma these ages support a multi phases emplacement of the viluy traps as is the case for many continental flood basalts because the age of the first volcanic phase is undistinguishable from recent determinations of the age of the frasnian famennian boundary our results further strengthen the hypothesis of a causal relationship between the two events the second phase of emplacement of the viluy traps occurred at the end of the devonian apparently slightly before the devonian carboniferous boundary finally except for the ordovician silurian extinction which remains to be associated with a volcanic province all major phanerozoic mass extinctions have been correlated with the emplacement of a cfb thereby reinforcing the possible causal link between these events

field examples of strike slip fault terminations in mongolia and their tectonic significance deformation at the ends of large intracontinental strike slip faults that do not simply link other major structures often involves rotations about a vertical axis we use earthquake slip vectors surface rupture in earthquakes and geomorphology to examine the ends of three major strike slip faults in mongolia in these places a simple pattern is seen consisting of a thrust fault on one side with a displacement that decreases away from the strike slip fault consistent with local rotational deformation strike slip faults that terminate in this way allow the style of faulting to change spatially within a deforming area for example from dominantly strike slip to dominantly dip slip while still accommodating the overall deformation required by larger scale regional motions such a change in fault style should also be accompanied by a change in the rotation rate about a vertical axis which may be detected paleomagnetically the kind of strike slip fault termination described here may have consequences for how large strike slip fxaults evolve and grow and for the variation in displacement along their length

lithospheric structure along wide angle seismic profile georift 2013 in pripyat dnieper donets basin belarus and ukraine

geomorphology and structure of the jid right lateral strike slip fault in the mongolian altay mountains abstract we describe the late cenozoic structure and evolution of the jid right lateral strike slip fault in the northern mongolian altay mountain chain parts of the jid fault have a vertical component of motion introduced by bending along the fault some locations show additional structural complexity at the earth s surface with parallel strands having strike slip normal and reverse faulting probably indicating a spatial separation of dip slip and strike slip components of motion in cross section the jid fault shows indications of recent movements at scales ranging from drainage re organisation at the kilometre scale to ground deformations likely to result from movements during the last earthquake which occurred 870 980 years ago based on osl dating of deposits exposed in trenching from the scale of the ruptures the earthquake would have had a magnitude of 7 5 with an estimated right lateral slip of 5 m numerous horizontal offsets of about 10 15 m and vertical scarps of 5 m in the youngest alluvial deposits show the likely cumulative movement over the last 15 000 years and suggest a maximum slip rate of roughly 1 mm yr the minimum cumulative right lateral slip on the jid fault is 1 km which would accumulate in 1 ma at present day rates of slip the relatively small vertical component of motion on the jid fault is not sufficient to generate topography in the adjacent kharkhiraa and turgen uul mountains with relief of over 2000 m the high mountains may therefore result from localised uplift on thrust faults rather than by oblique slip on the jid fault