structural and geochronologic data from the shin jinst area eastern gobi altai mongolia implications for phanerozoic intracontinental deformation in asia abstract the complex geology of central asia records significant phanerozoic growth and deformation of continental lithosphere yet many questions about the timing and mechanisms of these processes remain the gobi altai of southwestern mongolia preserves much of this history in exposed mountain ranges and sedimentary basins the shin jinst area near latitude 44 21 to 44 32 longitude 99 35 to 99 25 contains important evidence of paleozoic growth and accretion as well as subsequent mesozoic and cenozoic deformation detailed mapping and structural data including data sets on folds and cross cutting faults point to repeated episodes of deformation and add to recent work that documents triassic and jurassic compression as well as cenozoic tectonic activity in this region new 40ar 39ar data are interpreted to record permian to jurassic convergent margin processes in particular these data in combination with previous studies suggest that southern mongolia records protracted deformation throughout the jurassic that likely resulted from compression associated with the subduction zone at the southern margin of asia at that time

the role of attenuation in 2d full waveform inversion of shallow seismic body and rayleigh waves abstractfull waveform inversion fwi of rayleigh waves is attractive for shallow geotechnical investigations due to the high sensitivity of rayleigh waves to the s wave velocity structure of the subsurface in shallow seismic field data the effects of anelastic damping are significant dissipation results in a low pass effect as well as frequency dependent decay with offset we found this by comparing recorded waveforms with elastic and viscoelastic wave simulation the effects of anelastic damping must be considered in fwi of shallow seismic rayleigh waves fwi using elastic simulation of wave propagation failed in synthetic inversion tests in which we tried to reconstruct the s wave velocity in a viscoelastic model to overcome this q values can be estimated from the recordings to quantify viscoelasticity waveform simulation in the fwi then uses these a priori values when inferring seismic velocities and density a source wavelet correction which is inevitable in fwi of field data can compensate a

u pb zircon and geochemical constraints on the age origin and evolution of paleozoic arc magmas in the oyu tolgoi porphyry cu au district southern mongolia abstract uranium pb zircon ages are linked with geochemical data for porphyry intrusions associated with giant porphyry cu au systems at oyu tolgoi to place those rocks within the petrochemical framework of devonian and carboniferous rocks of southern mongolia in this part of the gurvansayhan terrane within the central asian orogenic belt the transition from devonian tholeiitic marine rocks to unconformably overlying carboniferous calc alkaline subaerial to shallow marine volcanic rocks reflects volcanic arc thickening and maturation radiogenic nd and pb isotopic compositions e nd t range from 3 1 to 7 5 and 206 pb 204 pb values for feldspars range from 17 97 to 18 72 as well as low high field strength element hfse contents of most rocks mafic rocks typically have 2 are consistent with magma derivation from depleted mantle in an intra oceanic volcanic arc the late devonian and carboniferous felsic rocks are dominantly medium to high k calc alkaline and characterized by a decrease in sr y ratios through time with the carboniferous rocks being more felsic than those of devonian age porphyry cu au related intrusions were emplaced in the late devonian during the transition from tholeiitic to calc alkaline arc magmatism uranium pb zircon geochronology indicates that the late devonian pre to syn mineral quartz monzodiorite intrusions associated with the porphyry cu au deposits are 372 ma whereas granodiorite intrusions that post date major shortening and are associated with less well developed porphyry cu au mineralization are 366 ma trace element geochemistry of zircons in the late devonian intrusions associated with the porphyry cu au systems contain distinct th u and yb gd ratios as well as hf and y concentrations that reflect mixing of magma of distinct compositions these characteristics are missing in the unmineralized carboniferous intrusions high sr y and evidence for magma mixing in syn to late mineral intrusions distinguish the late devonian rocks associated with giant cu au deposits from younger magmatic suites in the district

probabilistic tsunami hazard in the mediterranean sea 1 estimating the occurrence probability of natural disasters is critical for setting construction standards and more generally prioritizing risk mitigation efforts tsunami hazard in the mediterranean region has traditionally been estimated by considering so called most credible scenarios of tsunami impact for limited geographical regions but little attention has been paid to the probability of any given scenario we present here the first probabilistic estimate of earthquake generated tsunami hazard for the entire mediterranean sea we estimate the annual probability of exceeding a given tsunami amplitude at any coastal location in the region by applying a monte carlo based technique earthquake activity rates are estimated from the observed seismicity and tsunami impact is derived from deterministic tsunami wave propagation scenarios the highest hazard is in the eastern mediterranean owing to earthquakes along the hellenic arc but most of the mediterranean coastline is prone to tsunami impact our method allows us to identify the main sources of tsunami hazard at any given location and to investigate the potential for issuing timely tsunami warnings we find that the probability of a tsunami wave exceeding 1 m somewhere in the mediterranean in the next 30 years is close to 100 this underlines the urgent need for a tsunami warning system in the region

contrasting styles of mineralization in the chinese altai and east junggar nw china implications for the accretionary history of the southern altaids abstract the chinese altai east junggar collage in the southern altaids hosts three metallogenic belts which are from north to south 1 a volcanogenic massive sulphide vms cu pb zn belt 2 a belt of shear zone related gold deposits 3 a porphyry cu au mo belt the vms deposits formed in two pulses c 405 ma and c 375 ma in the chinese altai arc the porphyry deposits developed in three pulses in the east junggar arc the first two synchronous with the vms mineralization and the third at c 330 ma the shear zone related gold deposits developed in the late carboniferous to permian at the contact between the chinese altai and east junggar arcs time space distributions of diverse ore deposits across the altai east junggar collage indicate that the collage developed from two independent arcs the chinese altai and the east junggar the vms and porphyry deposits developed in the chinese altai and east junggar arcs respectively the chinese altai arc is interpreted to be a japanese type arc and the east junggar arc a mariana type arc during the latest palaeozoic the two arcs were juxtaposed by the erqis fault when many shear zone related lode gold deposits were emplaced these metallogenic distributions were a likely response to spatially localized mechanisms of crust growth and to the tectonic evolution of the altai east junggar collage and they are consistent with interpretation of the altaids as a multiple subduction accretion collage

kinematics and geochronology of multistage ductile deformation along the eastern alxa block nw china new constraints on the relationship between the north china plate and the alxa block abstract the ne trending bayanwula shan lang shan is an important tectonic belt lying between the north china plate ncp to the east and the alxa block to the west an understanding of its nature and the timing of deformation are essential to understand the relationship between the ncp and the alxa block two phases of ductile deformation have been observed in this belt large scale top to the west ductile thrusting characterized the early deformation in the bayanwula shan lang shan nearly east west trending quartz stretching lineations and lineations formed by amphibole and biotite are well developed different types of sheath and oblique folds with east west trending fold hinges are also developed in the region the shear strain of this ductile thrust is up to 17 the ductile deformation may have resulted from the top to the west thrusting of the northern part of the ncp over the alxa block and may have occurred ca 351 ma biotite 40 ar 39 ar age later ductile deformation was expressed as ne trending sinistral shear along the entire bayanwula shan lang shan and likely occurred ca 250 ma biotite and muscovite 40 ar 39 ar ages this shear may have resulted from the collision between the yangtze and north china plates to the south during the triassic combined with recently obtained detrital zircon u pb ages for the area the ductile deformation events in the eastern alxa block indicate that the block may not have been part of the ncp at least before the end of the devonian both blocks were located in the paleo asian ocean during the paleozoic and collided or amalgamated with each other at the end of the devonian

earthquake generated tsunamis in the mediterranean sea scenarios of potential threats to southern italy italian civil defense project development of new technologies for the protection of the italian territory from natural hazards funded by the italian ministry of university and research

tsunami hazard assessment of coastal south africa based on mega earthquakes of remote subduction zones the nuclear structural engineering pty and the national research foundation through the technology and human resources for industry programme project thrip tp2011061400009

alternative rupture scaling relationships for subduction interface and other offshore environments abstract alternative fault rupture scaling relationships are developed for m w 7 1 9 5 subduction interface earthquakes using a new database of consistently derived finite fault rupture models from teleseismic inversion scaling relationships are derived for rupture area rupture length rupture width maximum slip and average slip these relationships apply width saturation for large magnitude interface earthquakes approximately m w 8 6 for which the physical characteristics of subduction zones limit the depth extent of seismogenic rupture and consequently the down dip limit of strong ground motion generation on average the down dip rupture width for interface earthquakes saturates near 200 km 196 km on average accordingly the reinterpretation of rupture area scaling for subduction interface earthquakes through the use of a bilinear scaling model suggests that rupture asperity area is less well correlated with magnitude for earthquakes m w 8 6 consequently the size of great magnitude earthquakes appears to be more strongly controlled by the average slip across asperities the sensitivity of the interface scaling relationships is evaluated against geographic region or subduction zone and average dip along the rupture interface to assess the need for correction factors although regional perturbations in fault rupture scaling could be identified statistical significance analyses suggest there is little rationale for implementing regional correction factors based on the limited number of interface rupture models available for each region fault rupture scaling relationships are also developed for intraslab within the subducting slab extensional outer rise and offshore strike slip environments for these environments the rupture width and area scaling properties yield smaller dimensions than interface ruptures for the corresponding magnitude however average and maximum slip metrics yield larger values than interface events these observations reflect both the narrower fault widths and higher stress drops in these faulting environments although expressing significantly different rupture scaling properties from earthquakes in subduction environments the characteristics of offshore strike slip earthquake ruptures compare similarly to commonly used rupture scaling relationships for onshore strike slip earthquakes electronic supplement table of rupture parameters

shallow structure characterization by 2d elastic full waveform inversion assessing the effectiveness of elastic full waveform inversion fwi algorithms when applied to shallow 2d structures in the presence of a complex topography is critically important by using fwi we overcome inherent limitations of conventional seismic methods used for near surface prospecting acoustic tomography and multichannel spectral analysis of surface waves the elastic forward problem formulated in the frequency domain is based on a mixed finite element p0p1 discontinuous galerkin method to ensure accurate modeling of complex topography effects at a reasonable computing cost the inversion problem uses an fwi algorithm to minimize the misfit between observed and calculated data based on results from a numerical experiment performed on a realistic landslide model inspired from the morphostructure of the super sauze earthflow we analyzed the effect of using a hierarchical preconditioning strategy based on a simultaneous multifrequency inversion of damped data to mitigate the strong nonlinearities coming from the surface waves this strategy is a key point in alleviating the strong near surface effects and avoiding convergence toward a local minimum using a limited memory quasi newton method improved the convergence level these findings are analogous to recent applications on large scale domains although limited sourcereceiver offset ranges low frequency content of the source and domination of surface waves on the signal led to some difficulties regarding the impact of data decimation on the inversion results we have learned that an inversion restricted to the vertical data component can be successful without significant loss in terms of parameter imagery resolution in our investigations of the effect of increased source spacing we found that a sampling of 4 m less than three times the theoretical maximum of one half wavelength led to severe aliasing

end permian to mid triassic termination of the accretionary processes of the southern altaids implications for the geodynamic evolution phanerozoic continental growth and metallogeny of central asia the altaids is one of the largest accretionary orogenic collages in the world with the highest rate of phanerozoic continental growth and significant metallogenic importance it is widely accepted that subduction related orogenesis of the altaids started in the late precambrian and gradually migrated southward present coordinates however it is uncertain when and how the building of the altaids was finally completed based on structural geology geochemical geochronological and paleomagnetic data this paper presents late paleozoic to early mesozoic accretionary tectonics of two key areas north xinjiang in the west and inner mongolia in the east together with neighboring mongolia the late paleozoic tectonics of north xinjiang and adjacent areas were characterized by continuous southward accretion along the wide southern active margin of siberia and its final amalgamation with the passive margin of tarim which may have lasted to the end permian to early mid triassic in contrast in inner mongolia and adjacent areas two wide accretionary wedges developed along the southern active margin of siberia and the northern active margin of the north china craton which may have lasted to the mid triassic the final products of the long lived accretionary processes in the southern altaids include late paleozoic to permian arcs late paleozoic to mid triassic accretionary wedges composed of radiolarian cherts pillow lavas and ophiolitic fragments and high pressure ultrahigh pressure metamorphic rocks permian alaskan type zoned mafic ultramafic complexes intruded along some major faults of the tien shan we define a new tarim suture zone immediately north of the tarim craton that is probably now buried below the tien shan as a result of northward subduction of the tarim block in the cenozoic the docking of the tarim and north china cratons against the southern active margin of siberia in the end permian to mid triassic resulted in the final closure of the paleoasian ocean and terminated the accretionary orogenesis of the southern altaids in this part of central asia this complex geodynamic evolution led to formation of giant metal deposits in central asia and to substantial continental growth

seismic and landslide source of the 1908 straits of messina tsunami sicily italy 1 one hundred years ago december 1908 a devastating tsunami associated with an earthquake struck the straits of messina area causing many casualties on the basis of seismic data and observed runups and arrival times we suggest that the tsunami was likely generated by coseismic seafloor displacement coupled with a small submarine landslide triggered by the earthquake backwards ray tracing using a depth dependent velocity field submarine slope analysis and inferences form the main drainage network allowed us to identify possible locations for the source of the submarine landslide we then performed direct simulations of tsunamis generated by the earthquake and landslides and identified the tsunami source earthquake plus landslide that best fits observational data in a small volume submarine landslide 1 5 km3 located offshore nizza sicily

a rift system in southeastern central asian orogenic belt constraint from sedimentological geochronological and geochemical investigations of the late carboniferous early permian strata in northern inner mongolia china abstract the late carboniferous early permian is the most controversial period for the tectonic evolution of the southeastern central asian orogenic belt caob in this study we performed sedimentological and detrital zircon dating on the clastic sediments as well as zircon u pb age and geochemical analysis on the rhyolitic rocks of the late carboniferous early permian strata from northern inner mongolia china the sedimentological analysis showed that the late carboniferous early permian sediments are composed of continental clastic and volcanic rocks with basal conglomerate overlying the devonian strata the detrital zircon study revealed three age peaks at 300 ma 440 ma and 530 ma indicating that the clastic rocks derived from paleozoic magmatic rocks and pre carboniferous sediments from northern inner mongolia the age data revealed that rhyolitic rocks from northern inner mongolia extruded in two stages at late carboniferous and latest carboniferous early permian the late carboniferous rhyolites show i to a type granitic affinities whereas the latest carboniferous early permian rhyolites have a type granitic characteristics the difference suggests a transition of tectonic setting from post collisional extension to intraplate rift the late carboniferous early permian strata from northern inner mongolia and south mongolia show similar sedimentary facies detrital zircon age distribution and geochemistry features hence they were probably deposited in the same tectonic setting a unified block was finally proposed in northern inner mongolia and south mongolia where a rift system provided an intra continental sedimentary basin and induced intense syn rift magmatic activities the intra continental basin and syn rift magmatism indicate that the xing an airgin sum songliao hunshandake and south mongolia blocks in southeastern caob have been welded into a single continental block before the late carboniferous

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

the use of scenarios to evaluate the tsunami impact in southern italy this paper outlines the main contributions to the definition and evaluation of tsunami hazard and risk resulting from studies undertaken in italy in recent years and emphasises that adopting characteristic cases or scenarios is a very useful and advantageous technique three main cases are given as valuable examples that is the 1627 gargano tsunami the 1693 eastern sicily tsunami and the 1908 messina straits tsunami since 1 they characterise three distinct tsunamigenic regions 2 they are instances of destructive events and 3 they have been extensively studied in the last decade the paper elucidates the state of the art of the research on these events clarifies the chief points of agreement and disagreement among scientists and illustrates the main issues that are to be addressed by future research to provide reliable assessment of tsunami risk and to implement efficient countermeasures to defend the life of people coastal structures and the coastal environment against the attacks of tsunamis

structure and petrology of the altan uul ophiolite new evidence for a late carboniferous suture in the gobi altai southern mongolia altan uul and nemegt uul are mountain ranges in southern mongolia containing polydeformed mid to late palaeozoic sedimentary volcanic and metamorphic rocks uplifted at a restraining bend along the gobi tien shan left lateral strike slip fault system altan and nemegt uul contain part of an intra oceanic island arc that was active during the carboniferous thrust bound sequences of highly fractured pillow basalt cumulate gabbro peridotite serpentinite and jasperoid occur directly north of the arc rocks in at least three discrete belts and are interpreted to be fragments of an ophiolite metamorphosed marine sediments that have undergone intense contractional strain lie north of and structurally below the ophiolitic rocks the gabbros within the ophiolitic sequences have undergone prograde metamorphic reactions consistent with an ocean floor environment and trace element analyses are similar to those from cumulate gabbros of the oman ophiolite combined field and petrological evidence suggests that there is an east west trending south dipping late carboniferous suture in altan and nemegt uul that may be regionally correlated in the southern gobi altai region this proposed suture represents a new and important tectonic boundary between tectonostratigraphic terranes in southern mongolia requiring modification of existing models of late palaeozoic terrane accretion in the central asian orogenic belt

geophysical constraints for terrane boundaries in southern mongolia the central asian orogenic belt caob is a typical accretionary orogen divided into numerous lithostratigraphic terranes in theory these terranes should be characterized by contrasting magnetic and gravity signatures owing to their dissimilar petrophysical properties to test this hypothesis the extent of tectonostratigraphic terranes in southern mongolia was compared with the potential field data the analysis reveals that the terrane boundaries are not systematically defined by strong gravity and magnetic gradients the correlation of the magnetic signal with the geology reveals that the magnetic highs coincide with late carboniferous to early permian volcanic plutonic belts the matched filtering shows a good continuity of signal along the boundaries of these high magnetic anomalies toward the deeper crustal levels which may indicate the presence of deeply rooted tectonomagmatic zones the axes of high density bodies in the western and central parts of the study area are characterized by periodic alternations of nw se trending gravity anomalies corresponding to up to 20 km wide cleavage fronts of permo triassic age the matched filtering analysis shows good continuity of signal to the depth of these gravity highs which may indicate presence of deeply rooted high strain zones the magnetic signal is interpreted to be as the result of a giant permo triassic magmatic event associated with lithosphere scale deformation whereas the gravity pattern is related to the postaccretionary shortening of the caob between the north china and siberia cratons

zircon ages and geochemical compositions of the manlay ophiolite and coeval island arc implications for the tectonic evolution of south mongolia abstract numerous small dismembered ophiolite fragments occur in south mongolia but they are very poorly studied the lack of age data and geochemical analysis hampers our understanding of the paleozoic tectonic evolution of the region we conducted detailed studies on the manlay ophiolitic complex and huree volcanic rocks south of the main mongolian lineament mml to provide some constraints on these rocks the manlay ophiolite consists of dunite harzburgite pyroxenite gabbro plagiogranite basalt and chert locally with chromite mineralization in dunite the gabbro and plagiogranite yielded shrimp zircon weighted mean 206 pb 238 u ages of 509 5 ma and 482 4 ma respectively the basalt and dolerite samples of this complex show enrichment in lree and lile and negative nb ta and ti anomalies and the chrome spinel from the chromitite lens in the dunite is characterized by high cr and low tio 2 contents these features suggest a supra subduction zone ssz origin for the ophiolitic complex the huree volcanic rocks ranging from basalt to dacite display enrichment in lree and lile weak eu anomalies and distinctly negative nb ta and ti anomalies consistent with those of typical magmas in a subduction environment an andesite sample from this arc yielded a shrimp 206 pb 238 u zircon age of 487 5 ma which is the oldest reliable age for an island arc in south mongolia recognition of an early paleozoic ophiolitic complex and a coeval island arc indicates that south mongolia underwent a period of active volcanism during late cambrian to ordovician additionally the tuff overlying the ophiolitic complex and a granite intruding the ophiolite have shrimp zircon u pb ages of 391 5 ma and 304 4 ma respectively combining the available data we propose that the early paleozoic subduction accretionary complexes likely constitute the basement of the late paleozoic arc formations and correlate with the lake zone in western mongolia

granites of the southern mongolia carboniferous arc new geochronological and geochemical constraints the crust in southern mongolia is part of the central asian orogenic belt a vast accretionary orogen that records the opening and closure of the palaeo asian ocean in the late proterozoic to palaeozoic the crustal evolution of the region is revealed in basement inliers that also contain intrusion related porphyry ore bodies that are important mineral exploration targets the saykhandulaan inlier in southeast mongolia is a devonian carboniferous segment of island arc crust which is dominantly composed of extrusive and sedimentary lithologies but which also contains the oyut ulaan i type quartz monzonite intrusion a u pb zircon age for the oyut ulaan monzonite indicates emplacement at 330 0 0 5 ma to the east of the saykhandulaan inlier intrusive complexes dominate the neighbouring mandakh inlier new ages are presented for four of these plutons the bronze fox granodiorite 333 6 0 6 ma the narin hudag monzonite 333 2 0 6 ma the shuteen quartz monzonite 325 5 1 0 ma and the north mandakh granite 292 3 0 5 the intrusive bodies of the saykhandulaan and mandakh inliers have two distinct geochronological and geochemical associations 1 mid carboniferous i type monzonites that constitute the most easterly intrusive expression of the southern mongolia carboniferous arc and 2 early permian a type and peralkaline granites that represent a post orogenic phase of voluminous granite emplacement both groups are significantly younger than the nearby oyu tolgoi and tsagaan suvarga cu porphyry ore bodies which have previously been dated as early and late devonian respectively the new data presented here provide constraints on the timing of the transition from island arc magmatism to post collisional extension related magmatism in the region and possible controls on fertile and infertile granitoid intrusions with respect to cu au mineralisation

santorini eruption radiocarbon dated to 1627 1600 b c precise and direct dating of the minoan eruption of santorini thera in greece a global bronze age time marker has been made possible by the unique find of an olive tree buried alive in life position by the tephra pumice and ashes on santorini we applied so called radiocarbon wiggle matching to a carbon 14 sequence of tree ring segments to constrain the eruption date to the range 1627 1600 b c with 95 4 probability our result is in the range of previous less precise and less direct results of several scientific dating methods but it is a century earlier than the date derived from traditional egyptian chronologies

the crustal assembly of southern mongolia new structural lithological and geochronological data from the nemegt and altan ranges abstract the gobi altai region is an ideal setting for studying processes of continental growth and subsequent intracontinental and intraplate deformation including terrane accretion and dispersal ophiolite obduction crustal reactivation and intraplate mountain building to assess the diverse tectonic evolutionary models of the gobi altai and the wider region more field data and geochronological data are required to constrain the tectonic evolution of individual terranes and the relationship of adjacent crustal domains to each other throughout time in this paper we present new lithological structural and 40ar 39ar age data which constrain the crustal evolution across a previously unreported late paleozoic terrane boundary in the gobi altai nemegt and altan nuruu are topographically linked mountain ranges that were formed by miocene recent uplift at a right stepping restraining bend along the left lateral gobi tien shan fault system in southern mongolia ordovician carboniferous arc rocks and an ophiolite are exposed in the mountain ranges and form a small part of the east west arcuate trans altai zone field observations of rock types and structures combined with petrographic data are used to distinguish metamorphosed volcano sedimentary arc rocks in altan nuruu and western nemegt nuruu from arc rocks in central and eastern nemegt nuruu these distinct sequences are correlated with the dzolen and edrengin terranes in the trans altai zone along strike to the west integration of field data 40ar 39ar age data and published studies are used to describe a polyphase deformation history that includes late carboniferous ophiolite obduction mid permian to late triassic shortening and lateral terrane redistribution cretaceous rifting and late cenozoic intraplate mountain building

paleozoic multiple accretionary and collisional processes of the beishan orogenic collage in the paper by xiao and others american journal of science v 310 p 1553 1594 1 please substitute figure 16 reproduced here for figure 16 that appears between pages 1573 and 1574 the original figure 16 2 was printed at an improper size figure 3 1 lookup volpage 310

line source simulation for shallow seismic data part 2 full waveform inversion a synthetic 2 d case study full waveform inversion fwi of shallow seismic surface waves is able to reconstruct lateral variations of subsurface elastic properties line source simulation for point source data is required when applying algorithms of 2 d adjoint fwi to recorded shallow seismic field data the equivalent line source response for point source data can be obtained by convolving the waveforms with sqrt 1 t t traveltime which produces a phase shift of 4 subsequently an amplitude correction must be applied in this work we recommend to scale the seismograms with sqrt 2 r v ph at small receiver offsets r where v ph is the phase velocity and gradually shift to applying a sqrt 1 t time domain taper and scaling the waveforms with r sqrt 2 for larger receiver offsets r we call this the hybrid transformation which is adapted for direct body and rayleigh waves and demonstrate its outstanding performance on a 2 d heterogeneous structure the fit of the phases as well as the amplitudes for all shot locations and components vertical and radial is excellent with respect to the reference line source data an approach for 1 d media based on fourier bessel integral transformation generates strong artefacts for waves produced by 2 d structures the theoretical background for both approaches is presented in a companion contribution in the current contribution we study their performance when applied to waves propagating in a significantly 2 d heterogeneous structure we calculate synthetic seismograms for 2 d structure for line sources as well as point sources line source simulations obtained from the point source seismograms through different approaches are then compared to the corresponding line source reference waveforms although being derived by approximation the hybrid transformation performs excellently except for explicitly back scattered waves in reconstruction tests we further invert point source synthetic seismograms by a 2 d fwi to subsurface structure and evaluate its ability to reproduce the original structural model in comparison to the inversion of line source synthetic data even when applying no explicit correction to the point source waveforms prior to inversion only moderate artefacts appear in the results however the overall performance is best in terms of model reproduction and ability to reproduce the original data in a 3 d simulation if inverted waveforms are obtained by the hybrid transformation

early permian a type granites from central inner mongolia north china magmatic tracer of post collisional tectonics and oceanic crustal recycling abstract a type granitoids constitute volumetrically minor but genetically important building blocks of most post archean continental landmasses on earth and their diversified genesis encapsulates key information for ascertaining critical geodynamic controls on continental crustal formation and differentiation this zircon u pb dating and geochemical study documents the early permian peralkaline granites from central inner mongolia of china eastern central asian orogenic belt caob these granites show an a type magmatic affinity with typical enrichment in alkalis ga zr nb and y depletion in sr and p and fractionated ree patterns showing strong negative eu anomalies they have meaningful initial 87 sr 86 sr ratio of 0 70594 e nd t of 4 25 to 6 05 zircon e hf t from 9 8 to 16 0 and 18 o values from 2 41 to 4 72 these elemental and isotopic characters argue for parental magmas from partial melting of a newly trapped charnockitic lower crustal protolith and their subsequent fractional crystallization with an inherent hydrothermally altered oceanic crustal heritage and possible tectonic linkage to post collisional slab breakoff this kind of a type granites could not only serve as an insightful temporal milestone for monitoring the amalgamation between various constituent terranes in the caob but also present a spatial magmatic proxy for marking the maturation stage of juvenile crustal reworking during the final phase of a large orogenic event

palaeomagnetic and structural constraints on 90 anticlockwise rotation in sw mongolia during the permo triassic implications for altaid oroclinal bending preliminary palaeomagnetic results abstract new and published paleomagnetic measurements from trans altai and south gobi zones in south mongolia document large tectonic motions in between late carboniferous and triassic magnetic inclinations confirm equatorial position of south mongolian terranes in late carboniferous permian times the evolution of magnetic declinations indicates 90 anticlockwise rotation in between latest carboniferous and early triassic of all studied tectonic units around the eulerian pole located close to axis of mongolian orocline the anticlockwise rotation continues in triassic being accompanied by a major drift to the north the structural and published geochronological data suggest carboniferous e w shortening of the whole region resulting in n s trend of all continental and oceanic geological units followed by orthogonal n s shortening during late permian to early jurassic both paleomagnetic and geological data converge in a tectonic model of oroclinal bending of mongolian ribbon continent westerly back arc oceanic domain and mongol okhotsk subduction zone to the east the oroclinal bending model is consistent with the coincidence of the eulerian pole of rotation with the structural axis of mongolian orocline in addition the mesozoic collisional tectonics is reflected by late remagnetizations due to formation of wide deformation fronts and hydrothermal activity

transformation from 2 d to 3 d wave propagation for horizontally layered media the relationship between 2 d and 3 d wave propagation in horizontally layered media was first investigated by dampney 1971 in the last few years the usefulness and feasibility of transforming point source responses with 3 d geometric spreading to equivalent line source responses with 2 d geometric spreading have been thoroughly discussed see helgesen 1990 wapenaar et al 1990 1992 herrmann 1992 helgesen and kolb 1993 amundsen 1993 in the case of cylindrical symmetry this transformation constitutes a required preprocessing step for several seismic processing algorithms based on 2 d wave propagation the work of dampney 1971 has apparently been missed by the authors discussing the 3 d to 2 d geometric spreading transform

application of multi source waveform inversion to marine streamer data using the global correlation norm conventional multi source waveform inversion using an objective function based on the least square misfit cannot be applied to marine streamer acquisition data because of inconsistent acquisition geometries between observed and modelled data to apply the multi source waveform inversion to marine streamer data we use the global correlation between observed and modelled data as an alternative objective function the new residual seismogram derived from the global correlation norm attenuates modelled data not supported by the configuration of observed data and thus can be applied to multi source waveform inversion of marine streamer data we also show that the global correlation norm is theoretically the same as the least square norm of the normalized wavefield to efficiently calculate the gradient our method employs a back propagation algorithm similar to reverse time migration based on the adjoint state of the wave equation in numerical examples the multi source waveform inversion using the global correlation norm results in better inversion results for marine streamer acquisition data than the conventional approach

crustal evolution of the saykhandulaan inlier mongolia implications for palaeozoic arc magmatism polyphase deformation and terrane accretion in the southeast gobi mineral belt abstract the saykhandulaan inlier in south east mongolia lies within the central asian orogenic belt caob and records a complex history of palaeozoic tectonism and magmatism associated with terrane accretion on the northern margin of the palaeo asian ocean the inlier spans the boundary between the gobi altai back arc basin terrane in the north and the mandalovoo and gurvansayhan island arc terranes in the south which are notable for their many mineralised intrusions including the oyu tolgoi gold rich copper porphyry deposit results from cross strike transects within the saykhandulaan inlier reveal that it can be subdivided into five parallel east west striking litho tectonic domains 1 the northern slate belt comprising devonian greenschist grade pelites and psammites with deep marine to coastal siliciclastic protoliths 2 the saykhandulaan valley lineament zone svlz a tectonised zone of faulted and lithologically altered volcanic rocks 3 the high strain belt consisting of tightly folded and flattened metamorphosed clastic sedimentary rocks 4 the molasse succession consisting of relatively undeformed coarse conglomerates and sandstones and 5 the oyut ulaan volcanic group a nearly 5 km thick folded carboniferous volcanic succession that hosts the mid carboniferous oyut ulaan mineralised granite the northern slate belt metasedimentary rocks record a northerly cratonic provenance whereas all rocks to the south of the svlz have arc affinities the svlz is thus interpreted to be the boundary between the gobi altai and mandalovoo terranes two major deformation events are documented 1 back arc basin closure and inversion involving regional scale folding and greenschist grade metamorphism in the northern slate and high strain belts 2 contraction associated with mandalovoo terrane accretion and final closure of the palaeo asian ocean to the south following terrane accretion and cessation of subduction crustal extension and strike slip faulting further modified the crustal architecture of the inlier the results presented here provide a useful framework for understanding the crustal evolution of adjacent regions within the southeast gobi mineral belt

late carboniferous bimodal volcanic rocks and coeval a type granite in the suman khad area southwest mongolia implications for the tectonic evolution abstract the volcanic rocks in the suman khad area in southwest mongolia form a bimodal suite consisting mainly of peralkaline rhyolites with subordinate basalts the rhyolite sample collected from the bimodal suite yielded a shrimp zircon u pb age of 314 5 ma mswd 1 41 n 12 which was interpreted to represent formation time of the bimodal volcanic suite the basalts were characterized by enrichment in lile and lree and depletion in hfse indicating their formation was related to subduction processes these features together with their positive end t values 6 3 6 7 suggest that the basalts were likely derived from a depleted mantle source metasomatized by subduction related fluids in various tectonic discrimination diagrams the basalts exhibited a transition from true arc basalts to intraplate basalts and thus were suggested to from in a back arc tectonic setting the rhyolites show a close affinity to a type granites with enrichment in lile and lree depletion in nb ta and ti and positive end t values 6 0 6 4 considering the observed distinct compositional gap between the endmembers of the bimodal suite the rhyolites are proposed to originate from partial melting of juvenile basaltic crustal rocks rather than fractional crystallization of basaltic melt the granite associated with the bimodal volcanic rocks yielded a shrimp zircon u pb ages of 312 5 ma mswd 0 75 n 13 indicating that the granite is contemporaneous with the bimodal volcanic suite the granite samples showed typical a type granitic geochemical affinities and are considered to have been formed by partial melting of crustal rocks in a within plate tectonic setting based on a combination of the available data we suggest that the late carboniferous bimodal volcanic suite together with the coeval a type granites in the suman khad region probably document a back arc basin extensional environment which probably related to the roll back of the paleo asian oceanic plate during the northward subduction under the central mongolia microcontinent

structural framework of a major intracontinental orogenic termination zone the easternmost tien shan china the barkol tagh and karlik tagh ranges of the easternmost tien shan are a natural laboratory for studying the fault architecture of an active termination zone of a major intracontinental mountain range barkol and karlik tagh and lesser ranges to the north are bounded by active thrust faults that locally deform quaternary sediments major thrusts in karlik tagh connect along strike to the east with the left lateral gobi tien shan fault system in sw mongolia from a mongolian perspective karlik tagh represents a large restraining bend for this regional strike slip fault system and the entire system of thrusts and strike slip faults in the karlik tagh region defines a horsetail splay fault geometry regionally there appears to be a kinematic transition from thrust dominated deformation in the central tien shan to left lateral transpressional deformation in the easternmost tien shan this transition correlates with a general eastward decrease in mountain belt width and average elevation and a change in the angular relationship between the nne directed maximum horizontal stress in the region and the pre existing basement structural grain which is northwesterly in the central tien shan orthogonal to sh max but more east west in the eastern tien shan acute angular relationship with sh max ar ar ages indicate that major range bounding thrusts in barkol and karlik tagh are latest permian triassic ductile thrust zones that underwent brittle reactivation in the late cenozoic it is estimated that the modern mountain ranges of the extreme easternmost tien shan could have been constructed by only 10 15 km of late cenozoic horizontal shortening

gobi tianshan connections field observations and isotopes from an early permian arc complex in southern mongolia the tianshan orogen in the southern central asian orogenic belt consists of continental fragments stitched together during mid to late paleozoic arc magmatism generated by the closure of the paleo asian ocean controversy persists regarding the timing of final structural amalgamation of the region and therefore whether permian magmatism was generated in a subduction or intraplate environment based on new field mapping zircon u pb geochronology and isotope data from the 295 290 ma gobi tianshan intrusive complex in southwestern mongolia we argue that this complex is a voluminous intermediate batholith generated by subduction and that it is related to plutons of similar age and character in tianshan tectono magmatic belts to the west in the study area as well as in carboniferous and permian plutons across the tianshan mantle isotopic signatures remain consistently primitive permian plutons show an increase in radiogenic sr with no concurrent decrease in radiogenic nd which may be due to the influence of subducting continental sediment in the early permian this model explains the transitional nature of magmatic compositions and structures in the gobi tianshan intrusive complex

estimation of tsunami hazard in new zealand due to south american earthquakes we develop a probabilistic model for estimating the tsunami hazard along the coast of new zealand due to plate interface earthquakes along the south american subduction zone to do this we develop statistical and physical models for several stages in the process of tsunami generation and propagation and develop a method for combining these models to produce hazard estimates using a monte carlo technique this process is largely analogous to that used for seismic hazard modelling but is distinguished from it by the use of a physical model to represent the tsunami propagation as opposed to the use of empirical attenuation models for probabilistic seismic hazard analysis

2 d multiparameter viscoelastic shallow seismic full waveform inversion reconstruction tests and first field data application 2d full waveform inversion fwi of shallow seismic wavefields has recently become a novel way to reconstruct s wave velocity models of the shallow subsurface with high vertical and lateral resolution in most applications seismic wave attenuation is ignored or considered as a passive modelling parameter only in this study we explore the feasibility and performance of multi parameter viscoelastic 2d fwi in which seismic velocities and attenuation of p and s waves respectively and mass density are inverted simultaneously synthetic reconstruction experiments reveal that multiple crosstalks between all viscoelastic material parameters may occur the reconstruction of s wave velocity is always robust and of high quality the parameters p wave velocity and density exhibit weaker sensitivity and can be reconstructed more reliably by multi parameter viscoelastic fwi anomalies in s wave attenuation can be recovered but with limited resolution in a field data application a small scale refilled trench is nicely delineated as a low p and s wave velocity anomaly the reconstruction of p wave velocity is improved by the simultaneous inversion of attenuation the reconstructed s wave attenuation reveals higher attenuation in the shallow weathering zone and weaker attenuation below the variations in the reconstructed p and s wave velocity models are consistent with the reflectivity observed in a gpr profile

scenarios of earthquake generated tsunamis for the italian coast of the adriatic sea we calculated the expected impact on the italian coast of the adriatic sea of a large set of tsunamis resulting from potential earthquakes generated by major fault zones our approach merges updated knowledge on the regional tectonics and scenario like calculations of expected tsunami impact we selected six elongated potential source zones for each of them we determined a maximum credible earthquake and the associated typical fault described by its size geometry and kinematics we then let the typical fault float along strike of its parent source zone and simulated all tsunamis it could generate simulations are based on the solution of the nonlinear shallow water equations through a finite difference technique for each run we calculated the wavefields at specified simulation times and the maximum water height field above mean sea level then generated travel time maps and maximum water height profiles along the target coastline maxima were also classified in a three level code of expected tsunami threat we found that the southern portion of apulia facing albania and the gargano promontory are especially prone to the tsunami threat we also found that some bathymetric features are crucial in determining the focalization defocalization of tsunami energy we suggest that our results be taken into account in the design of early warning strategies

mongolian coal bearing basins geological settings coal characteristics distribution and resources abstract this paper presents geological settings stratigraphy coal quality petrography reserves and the tectonic history of the mongolian coal bearing basins this is based on a synthesis of the data from nearly 50 coal deposits the results of ultimate and proximate analyses and calorific value maceral composition and vitrinite reflectance data is given the coal deposits of mongolia tend to become younger from west to east and can be subdivided into two provinces twelve basins and three areas main controlling factor of coal rank is the age of the coal bearing sequences western mongolian coal bearing province contains mostly high rank bituminous coal in strata from late carboniferous the basins in southern mongolia and the western part of central mongolia have low rank bituminous coal in strata from the permian the northern and central mongolian basins contain mainly jurassic subbituminous coal whereas the eastern mongolian province has lower cretaceous lignite the carboniferous permian and jurassic coal bearing sequences were mainly deposited in foreland basins by compressional tectonic event whereas cretaceous coal measures were deposited in rift valleys caused by extensional tectonic event petrographically mongolian coals are classified as humic type vitrinite huminite groups of carboniferous permian and cretaceous coal range from 44 9 to 82 9 inertinite group varies between 15 0 and 53 3 but liptinite group does not exceed more than 7 jurassic coals are characterized by high percentages of vitrinite 87 3 to 96 6 and liptinite groups up to 11 7 this might be explained by paleoclimatic conditions mongolian coal reserves have been estimated to be 10 2 billion tons of which a predominant portion is lignite in the eastern mongolian province and coking coal in the south gobi basin

juvenile crustal recycling in an accretionary orogen insights from contrasting early permian granites from central inner mongolia north china abstract coeval high k calc alkaline to alkaline granites constitute important components of post collisional to post orogenic igneous suites in most orogenic belts of various ages on earth and their genesis harbors a key to ascertaining critical geodynamic controls on continental crustal formation and differentiation this zircon u pb dating and geochemical study documents three contrasting early permian granites from erenhot of central inner mongolia eastern central asian orogenic belt caob and reveals concurrent high k calc alkaline to alkaline granite association derived from successive partial melting of distinct protoliths the ca 280 ma gancihuduge gcg pluton shows a calc alkaline i type character with initial 87 sr 86 sr ratios of 0 7035 to 0 7039 e nd t of 1 87 to 4 70 zircon e hf t of 8 0 to 13 2 and 18 o from 7 4 to 8 7 the ca 276 ma cailiwusu cls pluton is magnesian and peraluminous with initial 87 sr 86 sr ratios of 0 7036 to 0 7040 e nd t of 1 9 to 2 4 zircon e hf t of 6 5 to 12 1 and 18 o from 9 7 to 10 9 these features are consistent with partial melts of mixed sources composed of newly underplated meta basaltic to andesitic protoliths and variable supracrustal components with distinctively higher proportion of the latter in the cls pluton by contrast the ca 279 ma kunduleng kdl suite exhibits an a type magmatic affinity with typical enrichment in alkalis ga zr nb and y e nd t of 2 39 to 3 55 zircon e hf t from 8 3 to 12 3 and 18 o values from 6 8 to 7 5 these features suggest that they stem from high temperature fusion of dehydrated k rich mafic to intermediate protoliths besides presenting a snapshot into a stratified crustal architecture in 18 o these contrasting granites could not only serve as a temporal marker for monitoring post collisional extension in the aftermath of a retreating subduction zone but also present spatial magmatic proxy for tracing crustal formation and differentiation within back arc basin environments in the caob

the tsunami induced by the 2003 zemmouri earthquake mw 6 9 algeria modelling and results summary a strong tsunami with sea disturbances observed along the algerian coast but with significant damage mainly in the balearic islands spain harbours affected the western mediterranean following the 2003 zemmouri earthquake m w 6 9 algeria an average regional uplift of 0 55 m was measured along the shoreline in the epicentral area field observations main shock and aftershocks characteristics are consistent with thrust along a 55 km long rupture trending ne sw dipping se the seismotectonic parameters indicate a hypocentre 7 8 km deep and a possible fault break between 5 and 15 km offshore several tide gauges located in the western mediterranean coast indicated an average of 0 4 m of sea level change with a maximum of 2 m in the balearic islands we generated high resolution bathymetry grids from the algerian coasts to the balearic islands coasts in order to test different seismic sources with different fault rupture location strike and dip and model the tsunami initiation and propagation for the modelling we employed the crank nicolson numerical schema with a finite difference method and the okada elastic dislocation theory for the fault rupture we also highlight the different factors responsible for waves amplification around the balearic coast the best fit between synthetic and real data tide gauges gps levelling and coastal uplift as compared to run up values are obtained for a thrust rupture comparable with the earthquake fault inferred from seismotectonic studies and located within 15 km offshore an analysis of t waves reinforces the earthquake rupture origin for the tsunami this study presents the results and modelling of a major tsunami recorded in the western mediterranean sea

the mongol okhotsk belt in mongolia an appraisal of the geodynamic development by the study of sandstone provenance and detrital zircons abstract the mongol okhotsk belt formed in a late stage of jurassic orogeny in the composite central asian orogenic belt the present paper investigates the late palaeozoic mesozoic sandstones associated with the belt in mongolia aimed at reconstructing the time and mode of ocean formation subduction and collision we apply provenance analysis including 1 heavy mineral and sandstone framework grain analysis 2 u pb laser ablation icp ms dating of detrital zircons for identifying contemporaneous volcanic arc activity and the recycling of older crustal material and 3 on dated zircon grains we analyze trace element contents and hf isotopic ratios in order to characterize the rock types in which they crystallized and the magma sources respectively the investigated samples are derived from 1 the adaatsag and doschgol terranes which represent the suture zone 2 the hangai hentei belt to the northwest and 3 the ereendavaa terrane and the middle gobi volcanic belt to the southeast of the suture the latter two are concurrent with the northern and southern margins of the mongol okhotsk ocean tectono stratigraphic arguments suggest that the mongol okhotsk ocean opened during the silurian within the early palaeozoic collage in the suture zone permian syn sedimentary zircon trace element contents confirm mafic rock sources and the mantle involvement in the magmatism epsilon hf t from 13 up to 20 n and s directed bi vergent subduction developed as revealed by contemporaneous zircons 1 along the northern margin hangai hentei from silurian early carboniferous subduction and accretion prevailed epsilon hf t from 3 up to 12 in associated zircons which was re initiated during the permian and 2 the contemporaneous silurian devonian southern margin ereendavaa middle gobi still represented an extensional continental margin showing reworking of neoproterozoic early palaeozoic zircons from the basement it turned into an active continental margin with starting arc magmatism in the carboniferous zircon mean epsilon hf t 5 75

geochemistry and geochronology of mississippian volcanic rocks from sw mongolia implications for terrane subdivision and magmatic arc activity in the trans altai zone abstract baaran and baytag terranes form important part of the trans altai zone of the central asian orogenic belt in the sw mongolia the trans altai zone represents an oceanic domain built by ordovician to devonian ophiolites covered by devonian carboniferous oceanic sediments this oceanic assemblage was intruded by a spectrum of carboniferous volcanic rocks ranging from basalts to rhyolites 325 6 1 4 ma to 351 0 5 9 ma la icp ms u pb dating on zircon that display similar whole rock trace element and sr nd isotopic signatures regardless their silica contents and the terrane they belong to they are normal k calc alkaline rocks whose nmorb normalized multielement patterns show an arc like enrichment in lile large ion lithophile elements and deep negative tnt ta nb ti anomalies based on the relatively high nb yb and th yb ratios the arc was probably formed on immature continental rather than typical oceanic crust low 87sr 86sr i 0 7043 0 7047 high e nd 350 5 2 to 5 8 and the observed in situ hf isotopic variation in dated zircons e hf t 7 4 to 13 are all attributed to a partial melting of primitive and youthful neoproterozoic ordovician arc type lower continental crust metamorphosed intermediate acid igneous rocks and or arc derived greywackes augmented with and most likely facilitated by contemporaneous arc related basaltic intrusions a distinct possibility remains the previously formulated model assuming that the carboniferous magmatism in gobi altai and trans altai zones sampled the juvenile neoproterozoic to cambrian arc crust relaminated under the ordovician devonian oceanic crust in any case the studied arc association together with lithological sequence of ophiolites can be closely correlated with the dulate arc in eastern junggar it is proposed that the two arc sequences form a single belt c 500 km long that represents one of the main known arc structures in the central asian orogenic belt

late triassic sinistral shear in the east gobi fault zone mongolia abstract tectonic studies of the east gobi fault zone in southeastern mongolia reveal multiple distinct intracontinental deformation events postdating late paleozoic arc accretion and continental amalgamation metamorphic tectonites of the tsagan subarga and tavan har blocks previously mapped as precambrian basement comprise a sinistral shear zone dominated by steeply dipping northeast striking foliations field observations and petrographic analyses indicate that the protoliths of the metamorphic tectonites are paleozoic arc volcanic and sedimentary sequences 40ar 39ar step heating analyses of minerals from pre syn and late to post kinematic lithologies bracket the timing of ductile sinistral shear as late triassic the main phase of distributed deformation associated with cooling through amphibolite upper greenschist facies conditions occurred ca 225 ma and shear zone activity waned ca 210 ma cooling rates inferred from the 40ar 39ar data are on the order of 40 20 c myr 1 apparent differences for the two basement blocks may reflect subsequent differential uplift during late jurassic cretaceous rifting relatively rapid late triassic cooling suggests a transtensional component to the deformation and is coincident with core complex formation in northern china late triassic intraplate deformation in southeastern mongolia is likely the result of far field forces associated with collision between mongolian arcs and the siberian craton i e closure of the mongol okhotsk ocean and or collisions associated with closure of the paleotethys the ductile shear zone has been documented over 250 km along strike and has been modified by subsequent brittle deformation events in the mesozoic and cenozoic

late paleozoic magmatic record of middle gobi area south mongolia and its implications for tectonic evolution evidences from zircon u pb dating and geochemistry abstract late paleozoic subduction accretion complexes occur widely in middle gobi area and provide a good opportunity for unraveling the paleozoic tectonic evolution of south mongolia the magmatic rocks in the tsavchir hudug district mainly consist of rhyolites and volcaniclastic rocks the rhyolites show enrichment in lree and lile and negative nb ta and ti anomalies indicating genesis in the subduction zone a rhyolite sample from the tsavchir hudug region yielded a shrimp 206pb 238u zircon age of 315 4 ma mswd 0 79 n 15 the andesite overlying the namdain hundy early paleozoic ophiolite shows adakite geochemical features and the two andesite samples yielded shrimp 206pb 238u zircon ages of 325 3 ma mswd 1 6 n 14 and 319 4 ma mswd 0 56 n 13 respectively suggesting that the carboniferous island arc formed on the basis of early paleozoic accretionary complex the granodiorite sample that intrudes the early paleozoic accretion complex with adakite geochemical features yielded a shrimp 206pb 238u zircon age of 333 4 ma mswd 1 6 n 16 representing the late paleozoic island arc intrusive the shrimp u pb analyses for the tuff sandstones that occur associated with early paleozic oceanic inliers in middle gobi area suggest detrital zircons mainly stem from the devonian carboniferous arc the age data obtained from the ophiolite 528 509 ma and tuff sandstone indicate the accretion in middle gobi area lasted from early paleozoic to late paleozoic for at least ca 200 ma suggesting the ocean of the accretionary complex was the major paleo asain ocean basin the subduction related magmatic belt in middle gobi area includes both early paleozoic and late paleozoic island arc activities which is consistent with the accretion duration time obtained from accretionary complex and also attests the argument of major paleo asain ocean basin

long term exhumation history of the inner mongolian plateau constrained by apatite fission track analysis the inner mongolian plateau along the southeastern flank of the wider mongolian plateau is a vast undulating surface ranging in elevation between 900 and 1500 m above sea level the peculiar topography of this area is assumed to be closely related to its complex tectono thermal evolution since late paleozoic the lithospheric structure of the plateau includes three continental blocks the mandula and the bart obo blocks form the southern margin of the central asian orogenic belt in that area and to the south the plateau includes the northern margin of the north china craton apatite fission track aft ages and track length distributions from 13 basement outcrops situated in the main tectonic blocks forming the inner mongolian plateau were determined in order to reconstruct its denudation history the thermal histories inferred from these data imply multi phased differential exhumation burying processes from the late paleozoic to the early cretaceous this complex thermal history is largely related to the early middle triassic closure of the paleo asian ocean the jurassic closure of the mongol okhotsk ocean and the early cretaceous orogenic collapse of the mongol okhotsk belt finally since late cretaceous no further major tectonic movement occurred and the inner mongolian plateau has been largely peneplained

plate interior polyphase fault systems and sedimentary basin evolution a case study of the east gobi basin and east gobi fault zone southeastern mongolia abstract structural interpretation of 2 d seismic reflection data and subsurface outcrop correlations reveal six distinct phases of deformation recorded in the paleozoic basement rocks and mesozoic cenozoic basin fill of the east gobi basin egb southeastern mongolia these phases include arc accretion and arc continent collision in late paleozoic time late triassic sinistral shear zone development early jurassic fold and thrust belt style shortening middle jurassic lower cretaceous extension and rift basin development middle cretaceous shortening with basin inversion and regional unconformity development and late cretaceous oligocene thermal subsidence with renewed paleogene left lateral strike slip faulting across the fault zone the five post amalgamation deformation phases are localized along the east gobi fault zone suggesting that preexisting structures and boundary conditions exert fundamental controls on the long term evolution of intracontinental basins such as the egb subsurface geophysical data and outcrop correlations demonstrate that the main subbasins of the egb contain major differences in basement metamorphic and structural fabrics basin fill patterns and distinct mesozoic cenozoic fault generations potential causes related to far field boundary conditions and other driving factors are suggested for each of the major deformation phases

eastern mediterranean tectonics and tsunami hazard inferred from the ad 365 earthquake historical accounts describe an earthquake and tsunami on 21 july ad 365 that destroyed cities and drowned thousands of people in coastal regions from the nile delta to modern day dubrovnik the location and tectonic setting of this earthquake have been uncertain until now here we present evidence from radiocarbon data and field observations that western crete was lifted above sea level by up to 10 m synchronously with the ad 365 earthquake the distribution of uplift combined with observations of present day seismicity suggest that this earthquake occurred not on the subduction interface beneath crete but on a fault dipping at about 30 within the overriding plate calculations of tsunami propagation show that the uplift of the sea floor associated with such an earthquake would have generated a damaging tsunami through much of the eastern mediterranean measurement of the present rate of crustal shortening near crete yields an estimate of 5 000 yr for the repeat time of tsunamigenic events on this single fault in western crete but if the same process takes place along the entire hellenic subduction zone such events may occur approximately once every 800 yr in the year ad 365 an earthquake and tsunami destroyed much of the eastern mediterranean coastal regions the distribution of uplift at the time suggests that the earthquake occurred on a fault within the overriding plate at the subduction zone beneath crete and not on the subduction interface itself

tsunami hazard evaluation of the eastern mediterranean historical analysis and selected modeling seismic sea waves in the eastern mediterranean have been reported since written history first emerged several thousand years ago we collected and investigated these ancient and modern reports to understand and model the typical tsunamigenic sources with the ultimate purpose of characterizing tsunami hazard along the levant coasts surprisingly only 35 of the tsunami reports could be traced back to primary sources with the balance remaining questionable the tsunamis varied in size from barely noticeable to greatly damaging and their effects ranged from local to regional overall we list 21 reliably reported tsunamis that occurred since the mid second century b c along the levant coast along with 57 significant historical earthquakes that originated from the local continental dead sea transform dst system an in depth evaluation shows that 10 tsunamis are clearly associated with on land dst earthquakes and therefore as formerly suggested they probably originated from offshore seismogenically induced slumps eight tsunamis arrived from the remote hellenic and cypriot arcs one from italy and two are left with as yet unrecognized sources a major conclusion from this work is that onshore earthquakes commonly produce tsunamis along the levant coastline and that analogous situations are present elsewhere in the mediterranean as well as along the california coast and in another regions with active faults near the coast we modeled three typical scenarios and in light of the sumatra experience we examined the more likely severe magnitudes this of course leads us toward the upper range of expected run ups the models show that sooner than five minutes after a strong earthquake produces an offshore slump which occurs after close to a third of the large dst earthquakes a 4 to 6 m run up may flood part of the syrian lebanese and israeli coasts tsunamis from remote earthquakes however arrive later and produce only 1 to 3 m run ups but are more regional in extent online material tsunami modeling and reports

application of a complete workflow for 2d elastic full waveform inversion to recorded shallow seismic rayleigh waves abstractthe s wave velocity of the shallow subsurface can be inferred from shallow seismic rayleigh waves traditionally the dispersion curves of the rayleigh waves are inverted to obtain the local s wave velocity as a function of depth two dimensional elastic full waveform inversion fwi has the potential to also infer lateral variations we have developed a novel workflow for the application of 2d elastic fwi to recorded surface waves during the preprocessing we apply a line source simulation spreading correction and perform an a priori estimation of the attenuation of waves the iterative multiscale 2d elastic fwi workflow consists of the preconditioning of the gradients in the vicinity of the sources and a source wavelet correction the misfit is defined by the least squares norm of normalized wavefields we apply our workflow to a field data set that has been acquired on a predominantly depth dependent velocity structure and we compare the reconstructed s wave velocity model with the result

source and short distance propagation of the july 9 1956 southern aegean tsunami abstract properties of the tsunamigenic source as well as the attenuation of the tsunami intensities of the large tsunami of july 9 1956 in the southern aegean are investigated this tsunami was generated by a shallow earthquake with a surface wave magnitude of 7 5 which was caused by a normal fault fault plane solution isoseismal lines and bathymetric information indicate that the tsunamigenic source had an elliptical shape with the large axis equal to 110 km and oriented in an ene wsw direction this is also the strike of the normal fault which produced the earthquake and it is probable that the southern block was downthrown linear relations between a the tsunami intensity and the epicentral distance for distances up to 330 km b the observed tsunami height and the epicentral distance and c the tsunami height and intensity have been determined this information concerning the source parameters of tsunamis and the attenuation of the tsunami intensity and tsunami height with distance are of great importance for determining the tsunami hazard in this area

structural constraints on the evolution of the central asian orogenic belt in sw mongolia we provide a detailed description of the structures along a 300 km long and 50 km wide transect across the central asian orogenic belt caob in southwestern mongolia covering the precambrian dzabkhan continental domain with overthrust neoproterozoic ophiolites in the north lake zone a silurian devonian passive margin association gobi altai zone and oceanic domain trans altai zone in the center and a continental area south gobi zone in the south structural analysis suggests late cambrian collapse of the thickened lake zone continental crust leading to stretching of the lithosphere and followed by silurian devonian formation of oceanic crust in the trans altai domain subsequent emplacement of devonian carboniferous and late carboniferous magmatic arcs occurred on the gobi altai and south gobi zone crusts respectively during e w shortening finally the entire system was affected by n s convergence from the permian to jurassic leading to heterogeneous shortening of the orogenic domain the model best fitting these observations is one of generalized westward drift of the tuva mongol dzabkhan baydrag ribbon continents during the silurian devonian associated with westward subduction of the mongol okhotsk ocean and sequential growth of syn convergent magmatic arcs back arc basins opened during this period in the area of the western paleoasian ocean the present day shape of the caob in southern mongolia was probably formed during permian to mesozoic anticlockwise rotation and folding of the tuva mongol dzabkhan baydrag continental ribbons combined with a strike slip transpressional reactivation of ancient transform boundaries in the paleoasian oceanic domain all continental and oceanic crustal domains were reactivated and intensely deformed during this convergence in a style controlled by crustal rheology and a heterogeneous permian magmatic thermal input the sequence of tectonic events is tested against published paleomagnetic data paleogeographic reconstructions and tectonic models leading to a revised model for the accretion of juvenile crust to a continental margin in the caob of southern mongolia

full waveform inversion of sh and love wave data in near surface prospecting we develop a two dimensional full waveform inversion approach for the simultaneous determination of s wave velocity and density models from sh and love wave data we illustrate the advantages of the sh love full waveform inversion with a simple synthetic example and demonstrate the method s applicability to a near surface dataset recorded in the village c achtice in northwestern slovakia goal of the survey was to map remains of historical building foundations in a highly heterogeneous subsurface the seismic survey comprises two parallel sh profiles with maximum offsets of 24 m and covers a frequency range from 5 hz to 80 hz with high signal to noise ratio well suited for full waveform inversion using the wiechert herglotz method we determined a one dimensional gradient velocity model as a starting model for full waveform inversion the two dimensional waveform inversion approach uses the global correlation norm as objective function in combination with a sequential inversion of low pass filtered field data this mitigates the non linearity of the multiparameter inverse problem test computations show that the influence of visco elastic effects on the waveform inversion result is rather small further tests using a monoparameter shear modulus inversion reveal that the inversion of the density model has no significant impact on the final data fit the final full waveform inversion s wave velocity and density models show a prominent low velocity weathering layer below this layer the subsurface is highly heterogeneous minimum anomaly sizes correspond to approximately half of the dominant love wavelength the results demonstrate the ability of two dimensional sh waveform inversion to image shallow small scale soil structure however they do not show any evidence of foundation walls

geology and geochronology of the xilamulun molybdenum metallogenic belt in eastern inner mongolia china the xilamulun molybdenum metallogenic belt located in eastern inner mongolia china has great economic potential as a major producer of molybdenum four major types of mo deposits have been recognized in the xilamulun molybdenum metallogenic belt porphyry quartz vein volcanic hosted and greisen these mesozoic mo deposits are closely related to si and k rich intrusives and are usually hosted by granite plutons or located at the endo or exo contact zones of the granite porphyry shrimp zircon u pb dating gives the emplacement ages of the intrusions related to mo mineralization as 245 1 4 4 152 4 1 6 and 139 1 2 3 ma re os analysis of five molybdenite samples from the chehugou porphyry mo deposit yields an isochron age of 245 5 ma 2 indicating that the mineralization age of the porphyry mo deposit is about 245 ma re os analyses of six molybdenite samples from the nianzigou quartz vein type mo deposit yield an isochron age of 154 3 3 6 ma 2 constraining the mineralization age of the quartz vein mo deposit to 154 ma our results suggest that the mo mineralization in the xilamulun belt formed during at least three stages i e the triassic late jurassic and early cretaceous and is coeval with the granitic magmatism the corresponding geodynamic background covers the syncollision between the north china and siberian plates during the early to middle triassic a compression setting related to the subduction of the paleo pacific plate during the jurassic and lithospheric thinning during the early cretaceous in eastern china

sinkhole detection using 2d full seismic waveform tomography we have developed an application of 2d time domain waveform tomography for detection of embedded sinkholes and anomalies the measured seismic surface wavefields were inverted using a full waveform inversion fwi technique based on a finite difference solution of 2d elastic wave equations and the gauss newton inversion method the key advantage of this approach is the ability to generate all possible wave propagation modes of seismic wavefields body waves and rayleigh waves that are then compared with measured data to infer complex subsurface properties the pressure wave p wave and shear wave s wave velocities are inverted independently and simultaneously the fwi was applied to one synthetic and two real experimental data sets the inversion results of synthetic data showed the useful capability of the waveform analysis in identifying an embedded void the inversion results of real data sets showed that the waveform analysis was able to delineate 1 an embedded concrete culvert and 2 a complex profile with an embedded void and highly variable bedrock laterally and vertically an independent invasive test standard penetration test was also conducted to verify the seismic test results

permian geodynamic setting of northeast china and adjacent regions closure of the paleo asian ocean and subduction of the paleo pacific plate abstract northeast china and adjacent regions are located in the central east asian continent and consist tectonically of both the paleo asian and paleo pacific orogens between the siberian platform and sino korean north china block this paper discusses some hotly debated issues concerning the permian geodynamic setting of these regions based on a comprehensive analysis of available geological geochemical paleobiogeographical and paleomagnetic data spatial and temporal distribution of ophiolites and associated continental marginal sequences permian sedimentary sequences spatial distribution and geochemistry of permian magmatic rocks and the evolution of paleobiogeographical realms imply 1 that the permian marine basins in northeast china and adjacent regions include remnants of the paleo asian ocean in southeastern inner mongolia and central jilin province and active continental margins of the paleo pacific ocean 2 that the suture between the siberian and sino korean paleoplates was finally emplaced in the permian and is located in areas from suolunshan solonker eastwards through regions north to the xar moron river in southeastern inner mongolia and then central jilin province to the yanji area and 3 that the permian crustal evolution of northeast china and adjacent regions as well as parts of the siberian paleoplate was influenced by subduction of the paleo pacific oceanic plate finally the permian tectonic framework and paleogeography of northeast china and adjacent regions in central east asia are discussed briefly and early and late permian palinspastic reconstruction maps are provided

late paleozoic mesozoic tectonic evolution of the trans altai and south gobi zones in southern mongolia based on structural and geochronological data abstract the trans altai zone in southern mongolia is characterized by thrusting of greenschist facies silurian oceanic rocks over devonian and lower carboniferous volcano sedimentary sequences by e w directed folding affecting the early carboniferous volcanic rocks and by the development of n s trending magmatic fabrics in the devonian carboniferous arc plutons this structural pattern is interpreted as the result of early carboniferous thick skinned e w directed nappe stacking of oceanic crust associated with syn compressional emplacement of a magmatic arc the southernmost south gobi zone represents a proterozoic continental domain affected by shallow crustal greenschist facies detachments of ordovician and devonian cover sequences from the proterozoic substratum whereas supracrustal carboniferous volcanic rocks and permian sediments were folded into n s upright folds this structural pattern implies e w directed thin skinned tectonics operating from the late carboniferous to the permian as demonstrated by k ar ages ranging from 320 ma to 257 ma for clay fractions separated from a variety of rock types moreover the geographical distribution of granitoids combined with their geochemistry and shrimp u pb zircon ages form distinct groups of carboniferous and permian age that record typical processes of magma generation and increase in crustal thickness the field observations combined with clay ages the geochemical characteristics of the granitoids and their ages imply that the e w trending zone affected by tectonism migrated southwards leaving the trans altai zone inactive during the late carboniferous and permian suggesting that the two units were tectonically amalgamated along a major e w trending strike slip fault zone this event was related to late carboniferous subduction that was responsible for the vast volume of granitoid magma emplaced at 300 305 ma in the south gobi and at 307 308 ma in the trans altai zones the formation and growth of the crust was initially due only to subduction and accretion processes during the post collisional period from 305 to 290 ma the addition of heat to the crust led to the generation of per alkaline melts once amalgamated these two different crustal domains were affected by n s compression during the triassic and early jurassic 185 173 ma resulting in e w refolding of early thrusts and folds and major shortening of both tectonic zones

tsunami hazard in the marmara sea turkey a numerical approach to discuss active faulting and impact on the istanbul coastal areas abstract the westward propagation of the seismic ruptures along the north anatolian fault naf during the 20th century has increased the probability that the next rupture will be located offshore in the marmara sea in the prolongation of the 1999 izmit earthquake faulting historical tsunamis have been evidenced in the marmara sea e g those associated with the 1509 may 1766 strong earthquakes that broke submarine parts of the naf in the vicinity of istanbul and future submarine events are expected to produce tsunamis as well that could be triggered either by submarine coseismic displacements or by landsliding the assessment of their amplitude and extent of their effects is discussed in this paper through numerical modeling based on both earthquake and landsliding sources we use a finite difference method that yields the maximum water levels reached in the marmara sea and the effects run up values around the coasts of istanbul using a set of three nested bathymetric grids with a decreasing cell size to focus on istanbul first we consider probable earthquake sources along the northern branch of the emerged naf namely in the eastern cinarcik basin magnitude mw 7 2 in the western tekirdag and central basins magnitude mw 7 5 and along the whole branch magnitude mw 7 6 the impact obtained in istanbul is all the more important as a normal component in the eastern basin is present and maximum water levels can reach 2 m along the shoreline provoking locally significant inundations these results show that the historical tsunami observations around istanbul 1509 may 1766 provided they are directly due to earthquake sources imply a significant normal component in the eastern basin whatever the extent of the rupture westward conversely a source located in the western and or central basin does not provoke large waves in istanbul e g august 1766 most probably finally we test three landslide sources in the southern vicinity of istanbul and show that the damage is expected to be larger than in the case of earthquake sources for moderate to large volumes involved this kind of source in addition to the coseismic deformation could therefore be a good candidate to explain the historical waves in istanbul especially in 1509 where run up values as high as 6 m have been reported provided we are confident in the historical documents available

line source simulation for shallow seismic data part 1 theoretical background equivalent line source seismograms can be obtained from shallow seismic field recordings by 1 convolving the waveforms with sqrt 1 t 2 applying a sqrt 1 t time domain taper where t is traveltime and 3 scaling the waveform with r offset sqrt 2 where roffset is source to receiver offset we require such a procedure when applying algorithms of 2 d adjoint full waveform inversion fwi to shallow seismic data although derived from solutions for acoustic waves in homogeneous full space this simple procedure performs surprisingly well when applied to vertical and radial components of shallow seismic recordings from hammer blows or explosions this is the case even in the near field of the force although the procedure is derived from a far field approximation similar approximative procedures recommended in literature are optimized for reflected waves and do not convert the amplitudes of all shallow seismic wavefield constituents equally well we demonstrate the suitability of the proposed method for the viscoelastic case by numerical examples as well as analytical considerations in contrast to the proposed single trace procedure integral transform approaches are exact for all viscoelastic wavefield constituents of the near and far field in unknown 1 d heterogeneous structure unfortunately integral transform approaches suffer from artefacts in applications to data sampled on 2 d structures here we use the fourier bessel integral transformation as a reference in 1 d heterogeneous structures we unroll the wave theoretical background of both approaches in order to demonstrate why the simplistic single trace simulation approach derived from the asymptotic acoustic case can perform so well when applied to the shallow elastic wavefield further we give recommendations for practical implementation and application to field data of the proposed simulation method and compare to the results of alternative conversion rules the performance of the conversion procedure to data recorded on 2 d heterogeneous structures is presented in a companion study by fwi reconstruction tests

runup distribution for the 1908 messina tsunami in italy observed data versus expected curves the source of the catastrophic 1908 messina tsunami southern italy is studied by best fitting the available datasets of observed runup with a previously published empirical function i e the expected runup distribution the maximum runup is 12 m and was measured 30 40 km to the south of the area where the maximum coseismic dislocation and mercalli cancani sieberg mcs intensities were recorded the observed runup drops from 12 m to less than 1 m in a few tens of kilometers the comparison between observed and expected runup distributions suggests that the main cause of the 1908 tsunami was a mass failure thus supporting previously published evidence including tsunami arrival times bathymetric maps and chronicles reporting the interruption of submarine cables this article adds a significant case history to the very limited database of thoroughly documented runup for landslide tsunamis

the hulan group its role in the evolution of the central asian orogenic belt of ne china the hulan group of central jilin province northeastern ne china consists of felsic volcanic and sedimentary rocks that underwent sub greenschist to amphibolite facies metamorphism and multiple phases of deformation during formation of the central asian orogenic belt young nd model ages of 1100 ma obtained in this study do not support earlier models that the hulan group was either rifted from the north china craton to the south or from the jiamusi block to the north since both these blocks have much older nd model ages detrital zircon u pb ages from a meta sedimentary rock of the hulan group define a maximum age of deposition of 287 6 ma not early palaeozoic as previously believed rb sr mineral isochron data indicate that metamorphism of the hulan group occurred at 250 ma this conclusion is further supported by an age of 248 4 ma for the dayushan granite which intruded the hulan group these new isotopic data together with evaluation of the regional geology indicate that final oceanic closure in the chinese segment of the central asian orogenic belt took place in the late permian the hulan area is located along the solonker xra moronchangchun suture that extends from inner mongolia across to central jilin province it is this zone that marks the final ocean closure resulting in the amalgamation of the north china and siberian cratons 2007 elsevier ltd all rights reserved