end permian catastrophe by a bolide impact evidence of a gigantic release of sulfur from the mantle our studies in southern china have revealed a remarkable sulfur and strontium isotope excursion at the end of the permian along with a coincident concentration of impact metamorphosed grains and kaolinite and a significant decrease in manganese phosphorous calcium and microfossils foraminifera these data suggest that an asteroid or a comet hit the ocean at the end of permian time and caused a rapid and massive release of sulfur from the mantle to the ocean atmosphere system leading to significant oxygen consumption acid rain and the most severe biotic crisis in the history of life on earth

a tectonostratigraphic framework for the mid norway region abstract the tectonostratigraphic analysis presented here aims to establish a broad stratigraphic framework within which the likely distribution of both reservoir and source rock intervals within the deep water voering and more basins can be evaluated in terms of hydrocarbon potential the devonian to triassic interval can be effectively discounted by its extreme depth of burial across most of the study area the middle jurassic is interpreted to provide a potential reservoir target in the gjallar ridge area the cretaceous is seismically mappable across the region and has been divided into five tectonostratigraphic sequences late cretaceous reservoirs are considered to offer targets in the nyk high area six tectonostratigraphic sequences are described within the cenozoic succession paleocene reservoirs are interpreted to offer targets over both the ytterskallen and ormen lange areas of the more basin source rock maturity is critical for exploration success mapping shows the late jurassic earliest cretaceous spekk formation to be overmature over most of the area though the presence of possible dhis indicates the probable presence of major gas accumulations in the region only on the western flank of the vigrid syncline does the spekk shallow sufficiently to lie within the potential oil window it is concluded that the region has the potential to become a significant new hydrocarbon province for the 21st century

multiple climatic changes around the permian triassic boundary event revealed by an expanded palynological record from mid norway here we present the palynological record from two shallow core holes 6611 09 u 01 and 02 from the trondelag platform offshore mid norway consisting of 750 m of upper permian and lower triassic sediments the relatively homogeneous assemblages recovered from the upper permian deposits are dominated by gymnosperm pollen mainly pteridosperms at the base of the griesbachian numerous spore species appear in the record leading to an increased diversity the change at this boundary is also marked by the massive reduction of one group of pteridosperm pollen vittatina together with other typical permian elements e g lueckisporites virkkiae this group is rare but consistently present in the lower part of the griesbachian and it gradually disappears in its upper part the distribution of other groups such as taeniate and non taeniate bisaccate gymnosperm pollen pteridosperms and conifers shows no significant change across the boundary whereas spores and other gymnosperm pollen increase in diversity and abundance these changes coincide with the formational change between the schuchert dal formation upper permian and the wordie creek formation griesbachian equivalents late permian and griesbachian palynomorph assemblages display different patterns the former show a homogeneous composition of low diversity whereas the latter reflect diverse and variably composed floras the data suggest that the arid phase of the late permian was followed by a humid phase at the base of the griesbachian in the griesbachian section a succession of six distinct palynological assemblages phase ii vii can be inferred comparable changes have been described from east greenland the variations in the palynological record are interpreted to reflect changing ecological conditions e g changing humidity comparable variations in the distribution of 13 c isotope values reported from various sections from greenland and china showing stable values during the late permian and highly variable values during the griesbachian suggest common causes for the observed fluctuations multiphase volcanic activity of the siberian traps seems to be the most likely candidate to have caused the variations in the 13 c isotope as well as in the palynological record in contrast to the common claim that marine and terrestrial biota both suffered a mass extinction related to the permian triassic boundary event the studied material from the norwegian midlatitudinal sites shows no evidence for destruction of plant ecosystems the presence of diverse microfloras of griesbachian age supports the idea that the climate in this area allowed most plants to survive the permian triassic boundary event

u pb zircon geochronology and tempo of the end permian mass extinction the mass extinction at the end of the permian was the most profound in the history of life fundamental to understanding its cause is determining the tempo and duration of the extinction uranium lead zircon data from late permian and early triassic rocks from south china place the permian triassic boundary at 251 4 0 3 million years ago biostratigraphic controls from strata intercalated with ash beds below the boundary indicate that the changhsingian pulse of the end permian extinction corresponding to the disappearance of about 85 percent of marine species lasted less than 1 million years at meishan a negative excursion in 13 c at the boundary had a duration of 165 000 years or less suggesting a catastrophic addition of light carbon

tree ring recorded hydroclimatic change in tienshan mountains during the past 500 years abstract in central asia tree rings provide one of the best sources of paleoclimatological information however dendroclimatology has not been widely applied in the coniferous forests of central asia tree cores of picea schrenkiana from four sites in the hutubi river basin were developed into a 606 year tree ring width chronology the analyses showed that the tree ring width indices highly correlate with mean april may pdsi in the hutubi river basin mean april may pdsi of the hutubi river was reconstructed using the tree ring data with 41 5 of the variance explained the reconstructed series contains both high and low frequency climate signals our new pdsi reconstruction agrees reasonably well with the dry and wet periods previously estimated from tree rings in western tien shan the results reveal common climatic extremes over much of central asia spatial analysis shows that the pdsi reconstructions have strong common signals for the tien shan the first principal component of pdsi reconstructions in tien shan is significantly correlated with sea surface temperature in the eastern equatorial pacific ocean and atlantic ocean the linkages to the atlantic and pacific oceans suggest the connection of regional moisture variations to the asian monsoon and the westerlies

paleophysiology and end permian mass extinction physiological research aimed at understanding current global change provides a basis for evaluating selective survivorship associated with permo triassic mass extinction comparative physiology links paleontological and paleoenvironmental observations supporting the hypothesis that an end permian trigger most likely siberian trap volcanism touched off a set of physically linked perturbations that acted synergistically to disrupt the metabolisms of latest permian organisms global warming anoxia and toxic sulfide probably all contributed to end permian mass mortality but hypercapnia physiological effects of elevated pco2 best accounts for the selective survival of marine invertebrates paleophysiological perspectives further suggest that persistent or recurring hypercapnia global warmth also played a principal role in delayed triassic recovery more generally physiology provides an important way of paleobiological knowing in the age of earth system science 2007 elsevier b v all rights reserved

drought reconstructions for the continental united states abstract the development of a 2 lat 3 long grid of summer drought reconstructions for the continental united states estimated from a dense network of annual tree ring chronologies is described the drought metric used is the palmer drought severity index pdsi the number of grid points is 154 and the reconstructions cover the common period 1700 1978 in producing this grid an automated gridpoint regression method called point by point regression was developed and tested in so doing a near optimal global solution was found for its implementation the reconstructions have been thoroughly tested for validity using pdsi data not used in regression modeling in general most of the gridpoint estimates of drought pass the verification tests used in addition the spatial features of drought in the united states have been faithfully recorded in the reconstructions even though the method of reconstruction is not explicitly spatial in its design the drought reconstructions show that the 1930s dust bow

damage vibration couple control of rock mass blasting for high rock slopes abstract this paper focuses on the damage vibration couple control method which is appropriate for the blasting of high rock slopes firstly the correlation characteristic between the blasting damage depth and the peak particle velocity ppv was investigated with regression analysis based on the site measurement of several famous high rock slopes in china results demonstrate that a power function relationship could be found and the correlation coefficient exceeds 80 3d numerical simulation of blasting excavation was employed to verify the relationship and results agree well with that of site experiment then a new damage vibration couple control approach of high rock slopes was proposed by introducing an equivalent blasting vibration control standard ebvcs the mathematical description of ebvcs was determined with the stress attention law and the rationale was verified with the experimental and numerical data finally the damage vibration couple control approach was implemented carefully during the excavation of wudongde high rock slope and the optimization suggestion was put forward results demonstrate that the ppv in the radial direction is most suitable for the control approach the appropriate position of ebvcs established is at the inside of the berm the detonation distance could affect the correctness of damage vibration couple approach significantly and the ideal position is the nearest berm

blast wave induced spatial variation of ground vibration considering field geological conditions drilling and blasting is one of the most widely used methods for large scale excavation in rocks and soils however rock blasting can induce many adverse effects and the typical influence of rock blasting on the surrounding environment is illustrated in fig 1 explosion induces ground and structures vibration1 2 and annoying noise when the explosive is detonated an extremely high pressure pulse is generated which is transmitted into rock mass adjacent to the blast hole producing a dilatational wave that propagates away from the charge stress waves due to blasts may cause damage to the surrounding rock and furthermore when the wave reaches a free face or open fissure non transmission it will be reflected and converted into a tensile wave which may produce tensile cracking and spalling if the tensile strength of the rock is exceeded by the tensile wave 3 4 also due to the fact that some rock blasting projects are close to the inhabitant area the surrounding buildings may be damaged due to blasting induced ground vibration if large stress wave propagates in the soil foundation and shock wave propagating through the air 5 disruption of some business activities possible structural damage and emotional traumatized residents are the problems that need to be addressed 2 6 therefore the influence of ground vibrations on surrounding buildings sensitive devices and people in urban environments is a significant consideration in obtaining project approvals

deformation structures in organic rich shales seismic images of upper jurassic organic rich siliciclastic rocks are studied along the 2000 km 1243 mi norwegian margin these rocks are considered the main source rock for most of the large oil and gas fields in the north sea and norwegian sea we report characteristic seismic expressions of thin skinned gravitational gliding structures that are strata bound to the organic rich formations the most characteristic structures are listric faults that offset and rotate the upper part and sole out near the base of the organic rich zone these may be present in large areas 10 000 km2 3861 mi2 but are usually restricted to tilted areas the strike of the faults was perpendicular to the downdip direction of the movement of mass and fault directions can therefore be used as paleodip indicators several types of contraction structures are observed and all are formed at a maximum of a few hundred meters of burial although they are not limited to organic rich shales such strata bound structures may help identify organic rich intervals in basins where their presence is unknown we suggest that adding organic material to clay leads to reduced permeability compaction related vertical fluid flow may cause fluid overpressure to build up at the base of a less permeable organic rich layer during early burial this high fluid pressure zone becomes a low friction decollement surface on which overlying sediments slide to form characteristic thin skinned deformation structures

drought reconstruction in eastern hulun buir steppe china and its linkages to the sea surface temperatures in the pacific ocean abstract a tree ring width chronology covering the period 1780 2013 ad was developed from pinus sylvestris var mongolica for the eastern hulun buir steppe a region located on the edge of the eastern mongolian plateau china climate growth response analysis revealed drought stress to be the primary limiting factor for tree growth therefore the mean february july standardized precipitation evapotranspiration index spei was reconstructed over the period 1819 2013 where the reconstruction could account for 32 8 of the variance in the instrumental record over the calibration period 1953 2011 comparison with other tree ring based moisture sequences from nearby areas confirmed a high degree of confidence in our reconstruction severe drought intervals since the late 1970s in our study area consisted with the weakening east asian summer monsoon which modulating regional moisture conditions in semi arid zone over northern china drought variations in the study area significantly correlated with sea surface temperatures ssts in north pacific ocean suggesting a possible connection of regional hydroclimatic variations to the pacific decadal oscillation pdo the potential influence associated with el nino southern oscillation enso was primarily analyzed

principles of avo crossplotting hydrocarbon related avo anomalies may show increasing or decreasing amplitude variation with offset conversely brine saturated background rocks may show increasing or decreasing avo

rock damage control in bedrock blasting excavation for a nuclear power plant drill and blast is a major method for bed rock excavation in nuclear power plant engineering under blasting excavation blast induced vibration propagates in rock mass and induces damage to surrounding rock studying the characteristics of wave propagation and blast induced damage to rock mass is most important to restrict the damage extension in the present paper in support of the bedrock blasting excavation for the linao nuclear power plant project lnpp the site seismic survey and sonic wave test are presented to study the characteristics of wave propagation and the blast induced damage for rock mass the explosive load rock damage characteristics and peak particle velocity ppv attenuation law are also investigated by numerical simulation using commercial software it can be seen that the numerical simulation results agree well with that obtained by site monitoring based on the site monitoring and the numerical simulation the relationship between ppv at 30 m away from the charge hole and the damage depth of rock mass is established a simple method based on safety threshold of vibration velocity for rock mass to restrict the damage depth of rock mass under blasting excavation is presented according to the damage controlled method and the presented safety threshold of vibration velocity for rock mass the remained bedrock can be simply and effectively protected during blasting excavation c 2010 elsevier ltd all rights reserved

hydroclimatic changes in china and surroundings during the medieval climate anomaly and little ice age spatial patterns and possible mechanisms abstract investigating hydroclimatic changes during key periods such as the medieval climate anomaly mca 1000 1300 ad and the little ice age lia 1400 1900 ad is of fundamental importance for quantifying the responses of precipitation to greenhouse gas induced warming on regional and global scales this study synthesizes the most up to date and comprehensive proxy moisture precipitation records during the past 1000 years in china and surroundings the proxy data collected include 34 records from arid central asia aca and 37 records from monsoonal asia our results demonstrate a pattern of generally coherent regional moisture variations during the mca and lia in mid latitude asia north of 30 n monsoonal northern china north china and northeast china was generally wetter while aca northwest china and central asia was generally drier during the mca than in the lia a west east mode the boundary between wetter northern china and drier aca was roughly consistent with the modern summer monsoon boundary in monsoonal china to the east of 105 e the northern part was generally wetter while the southern part was generally drier during the mca than in the lia a north south mode with a boundary roughly along the huai river at about 34 n these spatial patterns of moisture precipitation variations are also identified by instrumental data during the past 50 years in order to understand the possible mechanisms related to the moisture variations during the mca and lia we investigate the major sst and atmospheric modes e g the el nino southern oscillation enso the atlantic multidecadal oscillation amo and the north atlantic oscillation nao which affect the moisture precipitation variations in the study region using both the instrumental data and the reconstructed time series it is found that the enso may play an important role in determining hydroclimatic variability over china and surroundings on a multi centennial time scale and that the foregoing spatial patterns could be attributed to the la nina like el nino like condition during the mca lia in addition amo and nao may also have their own contributions

norwegian sea area permo triassic organic carbon rich deposits from seismic abstract seismic surveys of the permo triassic successions in norwegian sea sub basins have been studied to determine the distribution of organic carbon rich intervals in the deeper basinal areas upper permian to lower triassic organic carbon rich deposits had been described in cores from the margins of the basin but their distribution in the deeper parts of the basin was unknown the distribution of the organic carbon rich deposits in the deeper basin areas has been determined using a combination of amplitude versus angle offset ava avo analysis and an assessment of strata bound deformation structures ava avo anomaly class iv which has a negative normal incident reflection coefficient that decreases with angle offset has been used to predict the presence of organic carbon rich rocks in this work the intercept i and gradient g plots ig crossplots together with the near far angle amplitude comparison of the seismic surveys have been used to complement the interpretation the ig cross plotting was done by selecting small windows data probes along the intervals speculated to be organic carbon rich any data probe which displayed avo class iv elements on the ig crossplots and exhibited amplitude dimming with angle has been considered to indicate an organic carbon rich layer the results of this work show the presence of both upper permian and middle triassic organic carbon rich sediments in the deeper parts of sub basins within the froan and helgeland basins in the norwegian sea area two and one organic rich intervals are indicated in the froan and helgeland basins respectively the distribution of these organic rich rocks was partly tectonically controlled resulting in spatially limited deposits in the compartmentalized froan basin but more extensive deposits in the helgeland basin none of the lower triassic sections examined in this study showed ava avo characteristics indicative of organic carbon rich sediments on ig crossplots

a 189 year tree ring record of drought for the dzungarian alatau arid central asia abstract mountain systems are the most important sources of water in arid central asia aca it is therefore essential to understand past cycles of droughts and pluvials and to explore how future cycles might influence the sustainable utilization of regional water resources the palmer drought severity index pdsi is a widely applied measure of dryness that can be reconstructed from tree rings here a schrenk spruce picea schrenkiana fisch et mey tree ring chronology was developed for the dzungarian alatau of aca correlation and response analysis indicated that the pdsi from previous july to current june was the principal factor limiting radial growth the chronology was used to reconstruct the pdsi of the past 189 years for the dzungarian alatau a calibration model for the period from 1950 to 2011 explains 42 6 or 41 7 after adjusting for the loss of degrees of freedom of the actual pdsi variance the reconstructed pdsi might be representative of drought conditions for most of aca because it captures severe drought events in the 1910s and 1940s that were widespread across aca the extreme drought years 1917 and 1945 are especially pronounced a decadal analysis shows that the five periods in which the pdsi trend increased were 1830 1840s 1880 1890s 1920 1930s 1950 1960s 1980 2000s the pdsi declined in the 1850 1870s the 1900 1910s the 1940s and the 1970s the pdsi in aca exhibited a notably long and rapid wetting from 1980 to 2005 but decreased after 2005 in fact there have been three especially dry years 2008 2014 and 2015 in the last 10 years meanwhile there was large power in the 2 1 year 2 9 year 4 1 year 5 5 year 9 5 year and 10 8 year short periods and in the 30 40 year long periods

reconstructed precipitation on a centennial timescale from tree rings in the western tien shan mountains central asia july june precipitation has been reconstructed to 1756 ad for the western tien shan mountains central asia using the picea schrenkiana tree ring width the reconstruction explains 31 of the variation in the observed precipitation from 1933 to 2009 some extremely dry signals in the historical documents are captured precisely in this new reconstruction wet periods occurred during the periods of 1811 1828 1843 1880 1893 1915 1929 1934 and 1983 2002 while the periods 1766 1810 1829 1842 1881 1892 1916 1928 and 1935 1982 were relatively dry power spectral and wavelet analyses demonstrated the existence of significant 32 17 and 2 6 7 4 year cycles of variability an assessment of spatial correlation analysis and the significant correlation coefficients between the reconstructed precipitation series and three precipitation reconstructions indicate that our reconstruction might contain multiple large scale climatic signals in the low frequency domain a wetting trend in the eastern central asia since the 1970s decades was also captured by this reconstruction

westerlies asia and monsoonal asia spatiotemporal differences in climate change and possible mechanisms on decadal to sub orbital timescales abstract the westerlies dominated climatic regime wdcr in the present interglacial period was proposed because precipitation moisture variations between arid central asia and mid latitude monsoonal asia are out of phase or anti phased on different timescales during the holocene in this study we first review the development of the theoretical framework of the wdcr and then outline the boundary of its core area from the caspian sea in the west to the western hexi corridor in the east with the northern and southern limits coinciding with the domain of arid central asia next we present a synthesis of multiple lines of evidence for the occurrence of the wdcr on multi millennial sub orbital herein to decadal timescales during the holocene finally we examine the possible physical mechanisms responsible for the wdcr we find that external factors insolation changes induced by orbital factors generated the wdcr on a sub orbital timescale whereas a circum global teleconnection silk road pattern was the most significant factor responsible for the wdcr on centennial and decadal timescales the study provides a comprehensive summary of the development of our knowledge of the wdcr over the past several decades together with a tentative theoretical framework for understanding climatic and environmental changes within its region of influence in addition it forms a scientific basis for environmental management and ecological restoration in this arid region in the context of global warming

depositional environment and organic geochemistry of the upper permian ravnefjeld formation source rock in east greenland the upper permian ravnefjeld formation in east greenland is composed of shales that laterally pass into carbonate buildups and platforms of the wegener halvo formation the ravnefjeld formation is subdivided into five units that can be traced throughout the upper permian depositional basin two of the units are laminated and organic rich and were deposited under anoxic conditions they are considered good to excellent source rocks for liquid hydrocarbons with initial average toc total organic carbon values between 4 and 5 and hi hydrogen index between 300 and 400 the cumulative source rock thickness is between 15 and 20 m the source rocks are separated and enclosed by three units of bioturbated siltstone with a toc of less than 0 5 and an hi of less than 100 the e siltstones were deposited under relatively oxic conditions the organic geochemistry of the source rocks is typical for marine source rocks with some features normally associated with carbonate evaporite environments low pr ph pristane phytane low cpi carbon preference index distribution of tricyclic and pentacyclic terpanes the establishment of anoxic conditions and subsequent source rock deposition was controlled by eustatic sea level changes the subenvironment paleogeographic setting influx of carbonate material water depth salinity has some influence on a number of bulk parameters toc hi relations toc ts total sulfur relations and in particular biomarker parameters such as pr ph and terpane ratios all the basal shales or shales in the vicinity of carbonate buildups or platforms are characterized by low pr ph high c23 tricyclic terpanes and high c35 and c33 hopanes

nonbright spot avo two examples the use of amplitude variation with offset avo attribute sections such as the product of the normal incidence trace a and the gradient trace b have been used extensively in bright spot avo analysis and interpretation however while these sections have often worked well with low acoustic impedance bright spot responses they are not reliable indicators of nonbright spot seismic anomalies analyzing nonbright spot seismic data with common avo attribute sections will 1 not detect the gas charged reservoir because of near zero acoustic impedance contrast between the sands and encasing shales or 2 yield an incorrect negative avo product if the normal incidence and gradient values are opposite in sign we divide nonbright spot avo offset responses into two subcategories those with phase reversals and those without an avo analysis procedure for these anomalies is presented through two examples the procedure exploits the nature of the prestack response yielding a more definitive avo attribute s

pdsi variations at kongtong mountain china inferred from a 283 year pinus tabulaeformis ring width chronology 1 pinus tabulaeformis ring widths were used to reconstruct mean palmer drought severity indices pdsis from may to july for each of the past 283 years for kongtong mountain china a calibration model for the period from 1940 to 2005 explains 66 4 or 65 9 after adjusting for the loss of the degrees of freedom of the actual pdsi variance the reconstructed kongtong mountain pdsis could be representative of the moisture conditions of the entire loess plateau the reconstruction captures a severe 1927 1930 drought event that was widespread across all of northern china after 11 year moving average the reconstructed kongtong pdsi was found to compare well with other tree ring based temperature reconstructions from both huanglong in the eastern part of the chinese loess plateau and hokkaido japan this result indicates that high temperatures may be a major contributor to the severity of dryness at low frequencies significant 93 33 year and approximate 2 year cycles were observed in the kongtong tree ring chronology

rock physics analysis of clay rich source rocks on the norwegian shelf abstract rock physics trends and properties of clay rich source rocks are investigated in selected wells in the north sea and norwegian sea properties can vary significantly because of burial compaction composition diagenesis organic richness and maturation the many competing effects can be difficult to disentangle in traditional rock physics crossplots however nearly all the source rock data in the study are bounded nicely by linear trends that are based on rock physics models in acoustic impedance ai versus shear impedance si crossplots these reference models serve as a nice screening tool for organic richness and or maturation level i e hydrocarbon generation and expulsion regardless of burial depth the use of rock physics templates for the early mature to mature stage of clay rich source rocks is demonstrated by combining a simple basin modeling approach with a rock physics model using backus average in which the organic rich shale is represented by a transverse isotropic mixture o

a tree ring based record of annual mass balance changes for the ts tuyuksuyskiy glacier and its linkages to climate change in the tianshan mountains abstract fluctuations in glacier mass and volume are indicative of changes in the climate system they also strongly affect regional climate and hydrology in this paper we explore possible relationships between the radial growth of schrenk spruce picea schrenkiana fisch et mey and the mass balance of the tsentralniy tuyuksuyskiy ts tuyuksuyskiy glacier which is located on the northern slopes of the tianshan mountains in arid central asia we attempt to reconstruct the historical mass balance variability of the ts tuyuksuyskiy glacier using tree ring widths and stable carbon isotope chronologies the reconstruction is able to explain 62 1 of the variance in the annual glacier mass balance record over the 1965 2014 calibration period we also analyzed centennial mass balance variability and its linkages to climate change the ts tuyuksuyskiy glacier has a negative annual mass balance in most years and since 1968 has undergone the most rapid and longest melting process in the past 166 years the mass balance change of the glacier is controlled by the combination of temperature and precipitation conditions this study could be useful for more detailed glaciological hydrological and climatological assessments in this portion of the tianshan mountains

spatial distribution of excavation induced damage zone of high rock slope abstract the excavation induced damage zone edz can significantly influence the overall performance of an excavated slope determining the spatial distribution characteristics of the edz is very important to both design and construction of high rock slope based on the case study of the excavation of high rock slope at the xiluodu hydropower station in sichuan province of china spatial distributions of edz of the slope surface and berm were determined using sonic logging and cross hole sonic tests the results showed that the vertical damage depth increases non linearly from the inner side to the outer flank of the berm whereas the horizontal damage scope increases non linearly from the bottom to the top of the slope the maximum horizontal damage scope and the maximum vertical damage depth are found to be at the outer flank of the berm to reproduce and predict the edz for high rock slope excavation with dynamic finite element method a modified tensile compressive damage model was introduced into the simulation of the edz of xiluodu high rock slope four other frequently used damage models were used as comparisons the results demonstrate that the damage zone obtained by the modified tensile compressive damage model agreed with observations better than the other four existing blasting damage models

avo in transversely isotropic media an overview the amplitude variation with offset avo responses of elastic transversely isotropic media are sensitive to contrasts in both of thomsen s anisotropic parameters and e the equation describing p p reflections indicates that the smaller the contrasts in isotropic properties compressional velocity shear velocity and density and the larger the contrasts in and e across an interface of reflection the greater the effects of anisotropy on the avo signature contrasts in are most important under small to medium angles of incidence as previously described by banik 1987 while contrasts in e can have a strong influence on amplitudes for the larger angles of incidence commonly encountered in exploration 20 degrees and beyond consequently using rutherford and williams avo classification of isotropic gas sands type i gas sands overlain by a transversely isotropic ti shale exhibit a larger decrease in avo than if the shale had been isotropic and type iii gas sands overlain by a transversely isot

tree ring derived temperature records in the central loess plateau china using tree ring widths of pinus tabulaeformis carr trees mean temperatures from february to september were reconstructed for the kongtong mountain during the past 283 years the reconstruction could explain 43 7 of temperature variance during the calibration period from 1951 to 2004 it displays similar patterns to several temperature reconstructions in the loess plateau it corresponds well with the temperature regimes in hokkaido japan indicating that both regions have similar warm and cold intervals the high correlation between the reconstruction and the cru climatic research unit of university of east anglia uk ts3 temperature datasets showed that the temperature reconstruction could be representative of large scale climate change over northern china in addition the pacific decadal oscillation pdo affected temperature variations of northern china and even hokkaido to a certain extent

upper permian as a new play model on the mid norwegian continental shelf investigated by shallow stratigraphic drilling a 750 m thick fully marine succession of sandstones coarse grained turbidites shales and reworked sabkha sediments has been cored on the eastern margin of the mid norwegian shelf the succession has been dated as upper permian lower triassic and is comparable to rocks of the same age exposed onshore east greenland these data demonstrate that the marine depositional basin between greenland and norway extended much farther east than previously thought reddish shallow marine sandstones in the lower 170 m of the cored succession probably represent reworking of older sedimentary rocks present to the east of the drill sites this suggests that upper devonian lower permian sediments were deposited on caledonian basement east of the present day limits of the basin the cored succession also contains source rocks that can be stratigraphically correlated with the oil prone source rocks of the upper permian ravnefjeld formation onshore east greenland some of the cored sandstone intervals were stained with light nonbiodegraded oil that most likely was sourced from upper permian or alternatively lower triassic mudstones reworked fragments of reef building organisms in upper permian turbidites and upper permian carbonates encountered in an exploration well on the nordland ridge indicate that carbonate deposition and reef building occurred on structural highs on the trondelag platform the observations from the cored successions are key elements in a new paleozoic play model on the mid norwegian continental shelf and include the first evidence for the existence of an upper permian source rock in the area with upper permian carbonates or sandstones or triassic jurassic sandstones as reservoir begin page 108

geometry and kinematics of the triassic rift basin in jameson land east greenland the triassic rift basin along the east greenland margin described in this paper is represented by ne sw trending basins and highs segmented by nw se trending transfer zones coarse grained sediments along the eastern side of jameson land are shown to be hosted in half graben structures belonging to the carlsberg fjord basin that is bounded by nw dipping normal faults mapped and described after fieldwork in the klitdal area in liverpool land new aeromagnetic and electromagnetic data together with new drill cores allow the re interpretation of available seismic lines showing the continuation of the triassic rift basin toward the sw where it is buried under the upper triassic post rift sediments and the jurassic successions of the jameson land basin the n s trending liverpool land interpreted as the boundary block of the triassic basin is shown to represent a structural high inherited from the late carboniferous tectonics and faulted during the triassic rifting the carlsberg fjord basin and the klitdal fault system described in this paper should be seen as analogues to the helgeland basin in the norwegian offshore that is bounded by the ylvingen fault zone and to the papa and west of shetlands basins that are bounded by the spine fault the triassic rift zone and transfer faults on both conjugate margins shows a straightforward correlation with the trends of the initial spreading line and fracture zones of the north east atlantic indicating a possible inheritance of the triassic rifting

increased eurasian tropical temperature amplitude difference in recent centuries implications for the asian monsoon 1 a warmer eurasian continent and stronger land sea temperature gradient between eurasia and the tropical oceans contribute to an intensified summer monsoon we evaluate changes in the temperature difference between eurasia and the tropics over 250 years using proxies of eurasian surface air temperatures tree rings and tropical sea surface temperatures indo pacific corals these records show low frequency correspondence with each other over this interval and with other temperature and precipitation sensitive proxies from the asian monsoon regime greater warming is estimated for eurasia amplitude 1 70 0 28 c 1801 20 vs 1976 95 relative to the tropics 0 61 0 29 c 1806 25 vs 1937 56 the amplitude change from the 18th to 20th centuries is thus estimated to be about three times 1 5 6 greater over eurasia than the tropics this change may have contributed to an intensified asian monsoon system over recent centuries and to a decoupling of the monsoon and el nino southern oscillation in recent decades

tree ring based drought reconstruction at the northwestern margin of monsoon region of china since 1862 a tree ring width chronology developed from three sites of pinus tabulaeformis at the northwestern margin of the monsoon region of china was employed to study regional drought variability the drought reconstruction spanning 1862 2007 was developed by calibrating tree ring data with the palmer drought severity index pdsi an index indicating regional moisture conditions the reconstruction accounted for 43 3 of actual pdsi variance during their common period 1948 2005 droughts lasting over four years were found in 1877 1885 1889 1893 1925 1932 and 2004 2007 among which the droughts epochs in 1877 1885 and 1925 1932 were the two most severe and long lasting in the study area since 1862 there was an aridity aggravation trend since the mid 1970s in the reconstructed series which was consistent with the global temperature rise in records since 1975 this study indicated the feasibility of combining tree rings and the pdsi to reconstruct large scale drought patterns over this area and the pdsi reconstructed by tree ring may be a good proxy for the adjacent desert evolution

tree ring based drought reconstruction for the central tien shan area in northwest china 1 a robust ring width chronology developed from two sites of picea schrenkiana in the central tien shan area of northwest china was employed to study regional drought variability our analyses demonstrate both temperature and precipitation have significant effects on tree growth thus both should be considered for climate reconstruction regional drought history 1675 2002 a d was therefore reconstructed by calibrating with the palmer drought severity index pdsi our reconstruction not only captured well those extreme drought events recorded in local historical archives but also revealed the long term pattern of drought variability especially the trend of increasing moisture during the 20th century multi taper method spectral analysis indicates the existence of some low and high frequency cycles 146 171 11 5 10 6 9 7 6 1 3 9 3 4 3 2 2 4 and 2 1 yr overall our study indicates the feasibility of combining tree rings and the pdsi to reconstruct large scale drought patterns over this area

optimization of spherical cartridge blasting mode in one step raise excavation using pre split blasting abstract in one step raise excavation spherical cartridge blasting mode is easy to be implemented due to minimal requirement of the hole deviation nevertheless it may induce cumulative damage to the country rock this study firstly uses a validated rock model johnson holmquist model to simulate the damage evolution process of a raise by spherical cartridge blasting mode in ls dyna software then a field test is carried out to examine the numerical results of spherical cartridge blasting mode both the numerical and test results indicate that because of highly confined rock mass and restricted free face in deep raise a large charge is required in spherical cartridge blasting mode which leads to extensive damage on the wall of the raise in order to solve such a problem the pre split blasting technique is developed to optimize spherical cartridge blasting mode according to the subsequent numerical results the improved spherical cartridge blasting mode is successfully applied in another filling raise this study provides an effective solution to the difficulties that are encountered in one step raise excavation by spherical cartridge blasting mode

estimation of rock mass properties in excavation damage zones of rock slopes based on the hoek brown criterion and acoustic testing abstract when slopes are excavated in rock masses with the blasting method blasting and stress relaxation will produce an excavation damage zone edz in the remaining rock mass this study presents an estimation of the rock mass properties in the edz based on the generalized hoek brown failure criterion and the varying disturbance factor in this estimation the disturbance factor is quantified by using the acoustic p wave velocities tested in undamaged and damaged rock masses instead of a single constant value chosen from the descriptive guidelines statistical analysis of the acoustic test data shows that with an increase in depth behind the slope face the disturbance factor declines from 1 0 to 0 almost in a linear manner for blasting excavation of slopes in weaker rock masses the zone in the immediate vicinity of the slope face is fully damaged and thus over this range the disturbance factor remains the constant value of 1 0 as the disturbance factor linearly decreases within the edz the deformation modulus uniaxial compressive strength and equivalent cohesive strength of the damaged rock mass linearly increase to the undamaged values by assigning the varying parameters to the rock mass in the edz a numerical calculation based on the flac program is conducted to assess the slope stability it is found that using the varying rock mass parameters within the edz will yield completely different failure surfaces and factors of safety from that uses the constant parameters therefore it is significant to develop such an approach to quickly estimate the varying rock mass properties in the edz particularly when in situ tests are not available

tree ring width based precipitation reconstruction in zhaogaoguan china since 1805 ad abstract in order to further understand the past climate variation especially the history of drought and flood events in the east asian summer monsoon easm marginal area precipitation from previous august to current july for the period of 1805 2014 ad was reconstructed from a ring width chronology of pinus tabulaeformis in zhaogaoguan zgg a site located in the easm marginal area in northern china the transfer function can explain 46 4 adjusted to 45 4 for the loss of degrees of freedom of the variance of the observed precipitation during the calibration period 1958 2014 ad the reconstructed precipitation series revealed that the inter annual variability was very prominent 1843 and 1844 ad were the two wettest years while 1931 and 1999 ad were the two driest years we noticed that the droughts in 1900 1906 1931 1955 and 1999 ad in the reconstruction series corresponded to the severe floods in the yangtze river watershed in southern china during those same years this phenomenon confirmed the typical climate pattern of northern droughts and southern floods in china moreover the reconstructed precipitation series in zgg showed synchronous variation patterns with the other tree ring based hydrological reconstructions in the marginal area of easm on both inter annual and inter decadal scales indicating the common precipitation variation characteristics of the easm marginal area

can hydrocarbon source rocks be identified on seismic data hydrocarbon source rocks contain signifi cant volumes of organic matter are capable of expelling petroleum when heated and have produced most of the world s known oil volumes recently source rocks have also become recognized as unconventional economic reservoirs here we present a new way of identifying characterizing and mapping spatial distributions and variations of thick source rocks 20 m that is based on seismic data only this has a signifi cant impact on the prospect risk assessment of petroleum plays rock property studies of organic rich claystones show that the acoustic impedance ai which is the product of compressional velocity and density decreases nonlinearly with increasing total organic carbon toc percent claystones mixed with low density organic matter toc 3 4 have signifi cant lower ai and higher intrinsic anisotropy than otherwise similar nonorganic claystones this gives the top and base source rock refl ections characteristic negative and positive high amplitudes respectively which dim with increasing refl ection angle in addition the toc profi le which is a smoothed toc percent curve infl uences the top and base amplitude responses an upward increasing toc profi le has the highest amplitude at the top while the opposite asymmetry is observed for downward increasing toc profi les by using seismic data we therefore can map lateral distribution thickness variation in toc profi les and with local well calibration convert ai data to toc percent this approach to mapping source rocks may change the way petroleum systems are evaluated

a tree ring based precipitation reconstruction for the baluntai region on the southern slope of the central tien shan mountains china since a d 1464 abstract july june precipitation has been reconstructed back to a d 1464 for the baluntai region on the southern slope of the central tien shan mountains china using the picea schrenkiana tree ring width the reconstruction explains the variance of 51 in the observed precipitation from 1959 to 2005 by employing a 21 year moving average to the reconstruction nine periods with above average reconstructed precipitation comprised 1474 1503 1550 1577 1588 1619 1658 1713 1790 1812 1833 1867 1890 1907 1923 1944 and 1988 1995 eight periods with below average reconstruction consisted of 1504 1549 1578 1587 1620 1657 1714 1789 1813 1832 1868 1889 1908 1922 and 1945 1987 the wet dry periods of the reconstructed precipitation correspond well with other reconstructions some droughts in the historical documents are also precisely captured in the reconstruction precipitation variations for the southern slope of the central tien shan mountains are roughly synchronous with that of the northern slope in the recent 300 year power spectral and wavelet analysis demonstrated the existence of significant 100 y 60 y 50 y 16 y 10 y and 2 y cycles of variability

dynamic characteristics and safety criterion of deep rock mine opening under blast loading abstract the blasting vibration in deep mining affects the safety of the adjacent roadways to estimate the stability of a deep rock mass opening during blasting excavation the dynamic responses of the deep rock mass subjected to blast loading are investigated in this study the relationships between the blasting vibration velocity and the frequency over time horizontal distance and depth are analyzed and the stress distribution of the surrounding rock mass is depicted through field tests and numerical simulation the failure mechanism of deep rock mass is thus revealed and a new safety criterion regarding the blasting vibration of the deep rock mass is put forward the results indicate that the vertical vibration velocity is higher than the horizontal vibration velocity and that the vertical tension of the seismic wave of the blast is larger than that of the shearing action in the near blasting field which contrasts that of the far field both the vibration velocity and frequency decrease with an increase in time distance and depth and the range of influence of the blasting vibration in terms of depth is larger than that for the horizontal direction therefore the deep rock mass is more vulnerable to damage than the shallow rock mass under blast loading in addition the surrounding rock stress tends to transfer from the arc foot on the blasting side to the straight wall on the rear side and the shear stress is ahead of the tensile stress it was verified through a case calculation that the new criterion has practical value and can be used as a guide for evaluating the blasting vibration effects of the deep rock mass

incised submarine canyons governing new evidence of early triassic rifting in east greenland abstract regional studies of the uppermost permian and lowermost triassic successions in central east greenland have shown that sedimentation took place in half grabens during two phases of active rifting the permian triassic boundary locally contains submarine canyons up to several kilometres wide and several tens of metres deep formed in latest permian or earliest triassic times sandy and conglomeratic turbidites filling the canyons are highly variable in architecture depending on the structural setting and the geometry of the submarine canyons bounding surfaces also change character because of an asymmetric subsidence pattern of tilted fault blocks the submarine canyons have been studied on wegener halvo where exposures allow tracing of several canyons from the slope to the basin floor setting the canyons are interpreted to have developed from fluvial incised valleys furthest updip on the fault block and from turbidity current erosion further downdip the canyons have a se nw elongation while palaeocurrents were unimodal towards the nw reflecting the dip of the rotated fault block the canyon fill turbidites were deposited by consequent drainage on a nw dipping ramp like hangingwall slope within a half graben in areas between the canyons the permian triassic boundary is onlapped by triassic mudstones of offshore marine origin the studied succession is grouped into two facies associations 1 submarine gravity flow sandstones and conglomerates and 2 suspension deposited shales and mudstones traced down dip the submarine canyon fills display a change from chaotic conglomeratic and coarse sandy high density turbidites proximally to organised sandy turbidites basinwards farthest basinward a remarkable basin floor fan with well developed giant scale foresets is observed this trend reflects canyon widening and a decrease in gradient at the basin floor progradation of the turbidites was probably controlled by westward tilting of the fault block causing a steeper slope and subaerial exposure of a larger part of the proximal hangingwall above the fulcrum this resulted in erosion of the crestal area of the block that is upper permian and older successions and led to an increase in sediment supply to the downdip area accommodation space was created below fulcrum and downdip transgression governed back filling of the submarine canyons the observed eastward onlap of ammonite zones in shales and mudstones between the canyons was contemporaneous with the filling of the canyons a later drowning of the updip catchment caused decrease or shut off of sediment supply leading to deposition of shales and mudstones blanketing the sandy turbidites in the canyons the tilt of the studied fault block is interpreted to have caused simultaneous transgression below the fulcrum and regression with bypass or erosion above the fulcrum it is concluded that the tilted fault block setting has important consequences for sequence stratigraphic interpretations due to the asymmetric subsidence causing drastic changes in bounding surface character tectonism and sediment supply were the main controls on the stratigraphic architecture of the studied lower triassic succession on wegener halvo

effects of transverse isotropy on p wave avo for gas sands velocity anisotropy should be taken into account when analyzing the amplitude variation with offset avo response of gas sands encased in shales the anisotropic effects on the avo of gas sands in transversely isotropic ti media are reviewed reflection coefficients in ti media are computed using a planewave formula based on ray theory we present results of modeling special cases of exploration interest having positive reflectivity near zero reflectivity and negative reflectivity the avo reflectivity in anisotropic media can be decomposed into two parts one for isotropy and the other for anisotropy zero offset reflectivity and poisson s ratio contrast are the most significant parameters for the isotropic component while the difference between shale and gas sand is the most important factor for the anisotropic component for typical values of tl anisotropy in shale positive and e both difference and e difference e amplify avo effects for small angles of incidence plays a

palaeoenvironmental change and glacier fluctuations in the high tian shan mountains during the last millennium based on sediments from lake ala kol kyrgyzstan abstract a suite of limnological proxies measured in clastic sediments of the glacier fed lake ala kol ne kyrgyzstan document palaeoenvironmental change and glacier fluctuations in the central tian shan over the last millennium rock magnetic and geochemical data provide supporting evidence for three glacier expansion episodes occurring in 1200 1400 ce 1500 1850 ce and 1900 1950 ce and glacier retreat periods during 1000 1200 ce and the intervening periods the maximal glacier extent as inferred from high lf si inc coh ca inc coh and low arm30 arm is recorded between 1500 and 1850 ce and corresponds to cold and wet conditions during the little ice age in the high central tian shan periods of glacier waxing and waning recorded at lake ala kol present a close correspondence to ice accumulation rate in the northern tibetan plateau suggesting that precipitation changes are the main driver of glacier fluctuations in central tian shan during the last millennium although temperature may have exerted a more complex influence on centennial timescales

tree ring precipitation reconstruction in the chifeng weichang region china and east asian summer monsoon variation since a d 1777 1 the total precipitation of previous august to current july was reconstructed on the basis of the pinus tabulaeformis ring widths from three sites in chifeng and weichang regions china for the past 236 years the explained variance of reconstruction is 47 4 the intervals with below average precipitation 1768 2003 comprise 1779 1806 1853 1883 1926 1972 and 1980 1989 the intervals with above average precipitation consist of 1807 1852 1884 1925 1973 1979 and 1990 1999 precipitation in the study area is dependent on the east asian summer monsoon strength the reconstructed series is significantly correlated with the average dryness wetness index series of datong and beijing as well as with previous results from baiyinaobao helan mountains and even the state of mongolia a significant negative correlation r 0 63 p 0 0001 is also found between the reconstruction and our previously reconstructed temperatures of weichang for the period 1884 2002 our result suggests that the variations of the east asian summer monsoon on a decadal scale are coincident with the other regions within the environmentally sensitive zone of northern china as well as mongolia for the past 236 years and our reconstruction is representative of regional climate patterns

methods for source rock identification on seismic data an example from the tanezzuft formation tunisia abstract source rocks occurrence extension and quality in the subsurface are usually characterized directly from well data seismic characterization is however becoming an emerging technique for extending source rock properties beyond well locations and an effective tool for mapping their lateral and vertical heterogeneities the tanezzuft formation in tunisia an extremely organic rich source rock was used as a test for applying and comparing different seismic methods aimed at organic rich sequences characterization the data used consist of a 2d seismic line shot in the northern flank of the ghadames basin tunisia pre stack gathers extracted from an inline of a 3d survey and four wells with a complete set of wireline and petrophysical logs impedance inversion avo and seismic attributes were computed on the seismic lines and compared to well data impedance inversion together with a rock physics model of the formation generated a quantitative estimate of total organic carbon toc content in the studied 2d seismic line avo analysis showed a class iv and a base class iv response for the upper and lower reflectors delimiting the organic rich interval respectively seismic attributes analyzed the formation by exploiting its high impedance contrast and intrinsic anelastic attenuation the three methods here discussed showed coherent results both when compared each other and when compared with the well data and the regional geological model in particular avo and seismic attribute analysis are methods that can be applied without the need of well information and are then feasible methods for the investigation of source rock properties in undrilled basins

hydrometeorological reconstructions for northeastern mongolia derived from tree rings 1651 1995 reconstructions of annual prior august current july precipitation and streamflow 345 yr in length 1651 1995 are presented for northeastern mongolia based on tree ring width data these precipitation and streamflow reconstructions account for 54 and 48 of the respective variance in instrumental data over the past 50 years variations in instrumental precipitation and streamflow are within the range of those reconstructed over the length of tree ring records however there appear to be more frequent extended wet periods during the twentieth century multitaper spectral analysis revealed statistically significant peaks at 10 8 and 12 8 yr for the precipitation reconstruction and at 12 8 and 20 3 23 8 yr for the streamflow reconstruction similarly singular spectrum analysis identified spectral modes of variation at 12 and 21 yr for both series these spectra resemble those found for tree ring based precipitation reconstructions in central china as well as the western united states and may reflect solar influences on the climate of mongolia

tectonic development of the mid norway continental margin abstract the area reviewed covers the mid norway continental margin between latitudes 62 n and 68 n main structural elements as defined at the base cretaceous level are the trondelag platform underlying the inner shelf the more and voring basins located beneath the outer shelf and slope and the more platform and the outer voring plateau forming a base of slope trend of highs sediments contained in the mid norway basin range in age from late palaeozoic to cenozoic the basement was consolidated during the caledonian orogenic cycle devonian and early carboniferous wrench movements along the axis of the arctic north atlantic caledonides are thought to have preceded the namurian onset of crustal extension rifting processes were intermittently active for some 270 my until crustal separation between greenland and fennoscandia was achieved during the early eocene during the evolution of the norwegian greenland sea rift system a stepwise concentration of tectonic activities to its axial zone the area of subsequent continental separation is observed during the late palaeozoic to mid jurassic a broad zone was affected by tensional faulting during the late jurassic and cretaceous the trondelag platform was little affected by faulting whilst major rift systems in the more and voring basins subsided rapidly and their shoulders became concomitantly upwarped during the latest cretaceous and early palaeogene terminal rifting phase only the western more and voring basins were affected by intrusive and extrusive igneous activity following the early eocene crustal separation and the onset of sea floor spreading in the norwegian greenland sea the voring segment of the mid norway marginal basin subsided less rapidly than the more segment during the early and mid tertiary minor compressional deformations affected the voring basin and to a lesser degree the more basin tensional forces dominated the late palaeozoic to early cenozoic evolution of the mid norway basin and effected strain mainly in the area where the crust was weakened by the previous lateral displacements the lithosphere thinned progressively and the effects of the passively upwelling hot asthenospheric material became more pronounced massive dyke invasion of the thinned crust preceded its rupture

use of tree rings as indicator for groundwater level drawdown caused by tunnel excavation in zhongliang mountains chongqing southwest china tunnel excavation causes geological hydrological environmental and social changes the effects of groundwater level changes caused by tunnelling on tree growth have been poorly understood dendrochronology was used to evaluate the impact of groundwater level drawdown on tree growth tree cores of masson pines were collected from the areas affected by tunnel construction in the zhongliang mountains of chongqing in south western china to study the effects of tunnel excavation on the growth rate of trees by comparing with tree cores collected from unaffected areas excavation and early operation of the first tunnel in the zhongliang mountains from 1968 to 1984 caused a groundwater table drawdown in both karst aquifer and non karst aquifer the lowered groundwater table significantly reduced the growth rate of pine trees and the low growth rate remained for 15 years the effect was experienced up to at least 1 km from the tunnel axis the decline in tree growth was higher in karst than in non karst areas though the effects on the trees of the karst areas were lagging the high precipitation in 1998 contributed to groundwater recovery after which the tree growth recovered moderately but not to the original level groundwater leakage of the recently excavated tunnels did not affect pine trees heavily probably because the pines had adapted to the new hydrogeological conditions and new strategies in tunnel inflow management were adopted in the recently excavated tunnels the use of tree growth rate as an indicator of groundwater table change in tunnelling areas offers a new option to study environmental impacts and the extent of tunnelling effects

amplitude versus offset variations in gas sands seismic reflections from gas sands exhibit a wide range of amplitude versus offset avo characteristics the two factors that most strongly determine the avo behavior of a gas sand reflection are the normal incidence reflection coefficient r0 and the contrast in poisson s ratio at the reflector of these two factors r0 is the least constrained based on their avo characteristics gas sand reflectors can be grouped into three classes defined in terms of r0 at the top of the gas sand class 1 gas sands have higher impedance than the encasing shale with relatively large positive values for r0 class 2 gas sands have nearly the same impedance as the encasing shale and are characterized by values of r0 near zero class 3 sands have lower impedance than the encasing shale with negative large magnitude values for r0 each of these sand classes has a distinct avo characteristic an example of a gas sand from each of the three classes is presented in the paper the class 1 example involves a hartshorn channel s