horizontal wells in shallow aquifers field experiment and numerical model this paper is concerned with horizontal wells in shallow aquifers information about a field test is presented and the development of appropriate conceptual and computational models is discussed particular attention is paid to the processes of flow from the aquifer into the horizontal well and the hydraulic conditions within the well a combined computational model representing the aquifer and the horizontal well is developed this methodology is used to study a horizontal well in a shallow coastal aquifer a detailed pumping test is analysed using the combined model the combined model is then used to predict the consequences of increasing the abstraction lengthening the well or using the horizontal well for an extended period when there is no recharge the results from the combined model indicate that the commonly adopted assumptions of either a uniform flux into the well or a constant head along the well are not suitable for this field problem

hydraulic fracture reopening pressure and the estimation of maximum horizontal stress abstract in hydrofracture stress measurements the magnitude of the maximum horizontal stress s h is commonly estimated from the borehole pressure required to reopen an induced axial crack examination of the processes which govern the borehole pressure history recorded during the reopening cycle of such tests indicates two sources of error in the estimates of s h derived using the conventional method proposed by bredehoeft et al bredehoeft jd wolff rg keys ws and shutter e 1976 colorado geol soc amer bull 87 250 8 the first arises from the failure to include a term arising from pressure penetration into the crack prior to reopening in the force balance acting across the mouth of the induced axial cracks the problem can be remedied by using a modified reopening equation which includes pressure penetration of the crack the second source of error is more problematic and concerns the correct identification of the true reopening pressure from the borehole pressure records analysis of the process of reopening aided by numerical simulations shows that the true reopening pressure is generally less than the apparent i e that detected reopening pressure the discrepancy between true and apparent reopening pressures increases with larger hydraulic compliance of the test equipment the compliance in question refers to that of the fluid volume between the flow meter and the crack mouth s simulation of a pair of 1 m high axial cracks with 2 m residual hydraulic aperture in a 100 mm borehole indicates that the system compliance must be reduced to 5 10 7 m 3 mpa to enable the true reopening pressure to be estimated to better than 10 at flow rate is less than 10 4 m 3 s this is several orders of magnitude less than applies to conventional hydrofracture systems but is attainable for tests in small holes at shallow depth by making relatively minor system modifications tests at greater depth however would seem to require downhole measurement of flow at the packers we validate our assertions with a field test in which reopening pressure was determined mechanically and hydraulically

the occurrence of giant bivalve alatoconchidae from the yabeina zone upper guadalupian permian in european tethys abstract the permian gigantic bivalve family alatoconchidae forms a member of the tropical shallow marine fauna intimately associated with the tethyan warm water adapted verbeekinidae fusulines such as neoschwagerina and yabeina the velebit mountains in central croatia is one of the nine areas in the world that yielded alatoconchidae as first reported early in the 1970 s in addition to the neoschwagerina zone wordian middle guadalupian originally described we newly found alatoconchidae from the yabeina zone capitanian upper guadalupian from the brusane area in the central velebit mountains alatoconchidae occur in three stratigraphic levels of the velebit formation composed of black fusuline algal wackestone packstone with yabeina although fragmented the alatoconchidae shell reach sizes over 40 cm long and possess unique morphology with a lateral flange plus a prominent prismatic external layer in the double layered shell structure our results confirm for the first time in europe and thus in the western tethyan domain that the stratigraphic range of the gigantic bivalve family extends up to the capitanian as well as in the superocean panthalassa as no occurrence has been reported from the overlying lopingian upper permian alatoconchidae likely became extinct globally at the end of the guadalupian i e through the guadalupian lopingian boundary mass extinction

the paleomagnetism of single silicate crystals recording geomagnetic field strength during mixed polarity intervals superchrons and inner core growth 1 the basic features of the geomagnetic reversal chronology of the last 160 million years are well established the relationship between this history and other features of the field however has been elusive the determination of past field strength paleointensity is especially challenging commonly accepted results have come from analyses of bulk samples of lava historic lavas have been shown to faithfully record the past field strength when analyzed using the thellier double heating method data from older lavas however tend to show effects of in situ and laboratory induced alteration here we review an alternative approach single plagioclase crystals can contain minute magnetic inclusions 50 350 nm in size that are potential high fidelity field recorders thellier experiments using plagioclase feldspars from an historic lava on hawaii provide a benchmark for the method rock magnetic data from older lavas indicate that the feldspars are less susceptible to experimental alteration than bulk samples this resistance is likely related to the lack of clays in addition magnetic minerals are sheltered by the encasing silicate matrix from natural alteration that can otherwise transform the well defined thermoremanent magnetization into an irresolute chemical remanent magnetization if there is a relationship between geomagnetic reversal frequency and paleointensity it should be best expressed during superchrons intervals with few or no reversals thellier data sets based on single plagioclase crystals from lavas erupted during the cretaceous normal polarity superchron 83 120 million years ago suggest a strong 12 1022 am2 stable field consistent with an inverse relationship between reversal frequency and paleointensity superchrons may represent times when the pattern of core mantle boundary heat flux allows the geodynamo to operate at peak efficiency as suggested in some numerical models thellier data from single plagioclase crystals formed during times of moderate 10 reversals million years reversal occurrence suggest a weaker and more variable field these paleointensity data together with a consideration of paleomagnetic directions suggest that geomagnetic reversals field morphology secular variation and intensity are related the linkages over tens of millions of years imply a lower mantle control on the geodynamo on even longer timescales the magnetization held by plagioclase and other silicate crystals can be used to investigate the proterozoic and archean geomagnetic field during the onset of growth of the solid inner core data from plagioclase crystals separated from mafic dikes together with directional data from whole rocks indicate a dipole dominated field similar to that of the modern 2 5 2 7 billion years ago older archean rocks are of great interest for paleomagnetic and paleointensity investigations because they may record a time when the compositionally driven convection of the modern dynamo may not have been operating and a solid inner core did not play its current role in controlling the geometry of outer core flow most rocks of this age have been affected by low grade metamorphism investigations using single silicate grains provide arguably our best hope of seeing through secondary geologic events and reading the early history of the geodynamo absolute paleointensity measurements of the oldest rocks on the planet will require the further development of methods to investigate silicate crystals with exsolved magnetic minerals that address the uncertainties posed by thermocrystallization remanent magnetization anisotropy and slow cooling fortunately prior work in rock magnetism together with advances in analytical equipment and techniques provides a solid foundation from which these frontier issues can be approached

two methods for hydraulic fracturing stress measurements needless the ambiguous reopening pressure abstract two new methods were presented for stress measurements based on the hydraulic fracturing technique these are the methods i and ii which do not use the reopening pressure i e i the method using only the shut in pressures for transverse cracks and ii the method using the actual reopening pressure of a longitudinal crack which coincides actually with the reopening of the crack lip at the borehole wall the former method can be estimated the range of error in the evaluated magnitudes and orientations of the remote stresses these methods were applied to the results of hydraulic fracturing experiments performed at the kamaishi mine in japan the reliability of the evaluated stress field was confirmed by comparing the stress field with that evaluated by the over coring method

in situ stress determination from hydraulic injection test data laboratory and field results have shown that the orientation of a hydraulically propagated fracture is not always perpendicular to that of the minimum principal stress but may be influenced by local weakness planes such as preexisting natural fissures the lower the flow rate the stronger the weakness planes influence this observation has led to a new stress determination method based on the measurement of the normal stress supported by fracture planes with various dips and strikes this new method provides means to evaluate the precision of the stress determination and can be applied to situations in which none of the principal stresses is vertical when all the fracture planes are parallel to the borehole axis the method is still applicable if fast flow rate reopening pressures can be measured and if the principal stress directions are assumed to be independent of depth validity of the method is illustrated by analyzing results from two sets of data one of which has been discussed previously in the literature

mathematical model for calculating the horizontal principal stress of a faulted monoclinal structure in southwest qaidam basin china faulted monoclinal structures incorporate folds and faults their displacements cause stress release of differing degrees in various areas furthermore the faults commonly extend to the deep strata which may lead to the flow of boiling inclusions and localized thermal stresses a complex distribution of in situ stress appears in such areas which makes it challenging to drill wellbores in this study we first analyzed the geological structure and the factors influencing in situ stresses of a faulted monoclinal structure in southwest qaidam basin second based on huang s model a mathematical model for calculating the horizontal principal stress of the faulted monoclinal structure was developed considering the stress release from fault and fold displacements and the outflow from boiling inclusions third the magnitudes of the horizontal principal stresses of the study area were obtained using this new mathematical model and the predicted values had an average error of 2 63 according to a comparison with the results of the hydraulic fracturing field measurements fourth an in situ stress distribution in this area was established by combining the horizontal principal stresses magnitudes and the maximum horizontal principal stress direction finally based on the in situ stress distribution of the study area the mud density and trajectory for drilling the third stage of well z207 were determined the field application revealed that the design parameters met the engineering requirements satisfactorily which indicates that this mathematical model can predict the horizontal principal stress of the faulted monoclinal structure in southwest qaidam basin

stream depletion rate for a radial collector well in an unconfined aquifer near a fully penetrating river the stream depletion rate sdr is computed for a radial collector well installed in a semi infinite anisotropic homogeneous unconfined aquifer near a fully penetrating stream with a streambed with reduced conductivity for small pumping rates dimensional analysis and other arguments allow the sdr to be expressed as a function of eight parameters that describe the effect of properties of the aquifer and streambed as well as the configuration and placement of the well the calculations employ some results from huang et al 2012 j hydrol who expressed the sdr as a quintuple integral but by computing four of the integrals analytically the present solution requires less computational effort analytical calculation shows that the sdr in steady state does not depend on the streambed properties or any other parameters given enough time the flow through the streambed will equal the pumping rate of the well values of sdr are supported by comparing to previous solutions for special cases corresponding to appropriate limiting values of the parameters effects of the eight dimensionless parameters are studied systematically the properties of the streambed anisotropy of the aquifer and the position of the well affect the sdr more strongly than the orientation length and depth of the laterals

flow to a horizontal well in an aquitard aquifer system a horizontal well is sometime installed in an aquifer beneath a water reservoir to get significant amount of groundwater with better quality an aquitard often separates the surface water body from the underneath aquifer previous studies in vertical wells related to this subject treated leakage from the aquitard as a volumetric source term in the governing equation of flow in the main aquifer a hypothesis termed hantush s approximation for partially penetrating wells in this study flow in the aquitard and aquifer is treated as two systems which are linked through the continuity of flux and head at the aquitard aquifer boundary in particular we treat leakage as a boundary at the aquitard aquifer interface not as a volumetric source the leakage induced by the pumping horizontal well depends on several parameters such as the aquitard thickness the vertical hydraulic conductivity of the aquitard the aquitard specific storage the well location and the well length in general we find that the solution based on the hantush s approximation to some extent deviates from that obtained based on the actual scenario of leakage through the interface during the transient flow condition particularly at the early time for steady state flow the hantush s approximation works reasonably well under realistic conditions of aquitard thickness and hydraulic conductivity as long as the aquitard thickness is relatively thick aquitard aquifer ratio greater than 0 001 this approximation also works reasonably well under realistic horizontal well length and well location as long as the well is not too close to the aquitard aquifer boundary q 2005 elsevier b v all rights reserved

an analytical solution for tidal fluctuations in unconfined aquifers with a vertical beach 1 the perturbation technique has been commonly used to develop analytical solutions for simulating the dynamic response of tidal fluctuations in unconfined aquifers however the solutions obtained from the perturbation method might result in poor accuracy for the case of the perturbation parameter being not small enough in this paper we develop a new analytical model for describing the water table fluctuations in unconfined aquifers based on laplace and fourier transforms in the new approach the mean sea level is used as the initial condition and a free surface equation neglecting the second order slope terms as the upper boundary condition numerical results show that the present solution agrees well with the finite different model with the second order surface terms unlike teo et al s 2003 approximation which restricts on the case of shallow aquifers the present model can be applied to most of the tidal aquifers except for the very shallow one in addition a large time solution in terms of sine function is provided and examined graphically with four different tidal periods

comment on illawarra reversal the fingerprint of a superplume that triggered the pangean break up and the end guadalupian permian mass extinction by yukio isozaki recently isozaki 2009 has tried to explain how a series of catastrophic events which occurred on the surface of the planet over a 30 ma period straddling the permo triassic boundary were driven by deep earth processes the starting point for his hypothesis is the core perturbations of stable activity within the outer core possibly due to it being penetrated by large volumes of subducted lithospheric slab that had accumulated in the lower part of the mantle resulted in two ostensibly coeval events i an upward ascending superplume being generated at the core mantle boundary cmb and ii an instantaneous major change in the geomagnetic field s configuration from a fixed polarity state with an assumed high intensity to a low intensity system in which field reversals took place on a more normal 10 10 years the superplume is considered to have risen rapidly through the 2300 km thick lower mantle whereupon it began heating the base of the upper mantle iii within a geologically short period a number of geographically linked upper mantle plumes formed and rose to the earth s surface resulting in extensive mafic volcanism iv the devastating impact on the biota was principally a consequence of the increased cosmic radiation reaching the earth s surface as a result of the weakened geomagnetic field v it is thought that the radiation would have enhanced the cloud cover svensmark 2007 which when combinedwith the increased gases and aerosols associatedwith the eruptive activity would have contributed to the solar heat

isrm suggested methods for rock stress estimation part 3 hydraulic fracturing hf and or hydraulic testing of pre existing fractures htpf contents1 introduction 10112 summaryoftestmethods 10123 assumptionsandlimitations 10123 1 hydraulicfracturing hf 10123 2 hydraulictestsonpre existingfractures htpf 10124 apparatus 10134 1 fractureorientationdetectiondevices 10145 personnelquali cation 10146 equipmentperformance 10147 hydraulicfracturingtestprocedure 10148 hydraulic fracturedelineation 10168 1 impressionpackertechnique 10168 2 geophysicalimagingtechnique 10179 obtainingcriticalpressureparametersfromthepressure timerecords 101710 stresscalculations 101810 1 hydraulicfracturing hf 101810 2 hydraulictestsonpre existingfractures 101911 reportingofresults 1019references 1020

rifting in sw china structural and sedimentary investigation of the initial crustal response to emplacement of the permian emeishan lip detailed structural volcanic and sedimentary investigations of the crustal response to the emplacement of the middle late permian emeishan large igneous province show that a rifting system developed prior to the main stage of flood basalt eruptions in the form of sedimentary breccias clastic sedimentary deposits and mafic hydromagmatic units detrital zircon grains from sandstones yield 750 800 ma la icp ms 206 pb 238 u age clusters showing that material was sourced from the yangtze crystalline basement gabbros and pegmatites intruded along the normal faults of the rift system yield zircon ages of 264 260 ma and thus constrain the timing of rifting n s trending rift zones developed along the western flank of the pan xi palaeo uplift with ne sw and nne ssw trending rifts on the eastern side and along the western and eastern margins of the yangtze block the rifting progressed in pulses with an initial phase of normal faulting followed by rapid deposition of breccias later there was lower energy deposition of sandstone with accompanying rhyolitic eruptions this was followed by low energy sedimentation of mudstones and dolomites with accompanying hydromagmatic deposits rift system formation was constrained by a combination of far and near field tectonic stresses due to plate motions and lithospheric interaction with initial emeishan volcanism

precise age determination of mafic and felsic intrusive rocks from the permian emeishan large igneous province sw china abstract radiogenic isotopic dating using different mainly micro beam analyses techniques of rocks from the emeishan large igneous province elip has yielded a range of ages from the capitanian to the early triassic in contrast estimates based on paleontological and paleomagnetic data suggest the elip was emplaced rapidly 2 ma and that volcanism ended by 257 ma new zircon ca tims u pb ages that have superior precision compared to ages from micro beam analyses were obtained from strategic intrusive rocks of the panxi region inner zone of the elip the huangcao 258 9 0 7 ma daheishan 259 1 0 5 ma woshui 259 6 0 5 ma and cida 258 4 0 6 ma syenitic and granitic plutons and three mafic dykes 259 2 0 4 ma 259 5 0 8 ma 257 6 0 5 ma yielded a narrow range of ages between 257 ma and 260 ma the new results are consistent with the estimates from magneto biostratigraphic data and a rapid emplacement model the new wuchiapinqian ages of the huangcao and daheishan plutons suggests that magmatism may have lasted significantly less than 10 ma as previously suggested and the precise ages of the mafic dykes refute the hypothesis that emeishan high ti basalts represent the waning stages of the elip magmatism the short duration of magmatism also implies that degassing of the host sediments mostly carbonates and thus releasing of greenhouse gasses occurred within a substantially shorter interval than previously thought which significantly changes the loading of atmosphere per time unit the latter corollary potentially has severe environmental effects that may have contributed to causing the end guadalupian mass extinction

permeability creation and damage due to massive fluid injections into granite at 3 5 km at soultz 2 critical stress and fracture strength 1 the stress acting on fractures in a 3 5 km deep borehole in granite is examined to place constraints on fracture strength and to evaluate whether permeable fractures tended to be critically stressed two data sets consisting of some 500 fractures are analyzed the first considers the permeable impermeable fracture populations in their natural state the second considers the populations after the hole had been subject to a prolonged 9 mpa overpressure in two major injections which increased the number of permeable fractures from 18 to more than 95 for both data sets it is found that permeable fractures are critically stressed inasmuch as they support levels of shear stress that would be verging on failure if their strength were governed by a coulomb friction law with a coefficient of 0 6 1 0 however the vast majority of impermeable fractures are also critically stressed implying that critical stressing is a necessary but not a sufficient condition for permeability to develop most permeable fractures showed evidence of shear failure after the injections and tended to occur in hydrothermally altered cataclastic shear zones suggesting that they may have been relatively weak because of the presence of illite to prevent failure of the impermeable fractures during the injections requires a cohesion of at least 6 5 mpa to augment a maximum allowable friction coefficient of 1 0 these are probably early mode 1 fractures that are sealed primarily with calcite the strength of the shear zones appears to be significantly greater than the illite rich fractures from which they are composed this imposes constraints on their internal architecture

in situ stress measurements and regional stress field assessment in the xinjiang candidate area for china s hlw disposal abstract altogether 180 hydraulic fracturing hf in situ stress measurements were conducted in a pre selected area in the xinjiang uygur autonomous region china which is being considered as one of the candidate areas for china s high level radioactive waste hlw repository in situ stress magnitudes and orientations in three sub areas i e yamansu tianhu and aqishan sub areas were obtained from 163 valid measurement points in eight sub vertical boreholes at depths ranging from 17 to 647 m and the variation of the in situ stress components with depth was analyzed the measurement results show that the maximum horizontal stress is larger than the vertical stress within most of the measurement depth ranges indicating that the regional stress field is dominated by tectonic horizontal stress rather than by the overburden stress v within the range of the tested depths the stress field is characterized by h v h where h and h are the maximum and minimum horizontal stresses respectively fracture impression results reveal that the maximum horizontal stress is dominantly oriented in the nee sww direction which is in general in agreement with the orientation of regional tectonic stress field generated from movement of the earth s tectonic plates and is consistent with those interpreted by gps measurements and focal mechanism solutions in addition an abnormal phenomenon in performing stress measurements in one borehole was noticed and the result was discussed using borehole injection test data

analysis of long term variations in the geomagnetic poloidal field intensity and evaluation of their relationship with global geodynamics summary the 1167 published cooling unit cu palaeointensity estimates contained in the 400 10 ma portion of the pint global database were rigorously filtered according to accurate age determinations palaeodirectional reliability recognition of polarity and the method of palaeointensity acquisition the remaining 865 estimates group 1 were further filtered to ensure self consistency reducing the data set to 425 estimates group 2 group 1 and 2 data were clustered into temporally and or spatially distinct rock suites rs enabling each part of the record to be assessed for potential biasing by overrepresentation of palaeosecular variation psv the record was segmented according to the distribution of the data rather than using arbitrary time windows to ensure quasi consistent behaviour within each segment differences between these segments clearly indicate that a significant long timescale 10 7 and 10 8 yr variation of the mean geomagnetic poloidal field intensity gpfi occurred during the 400 10 ma period and hence that changing lowermost mantle conditions affect the capacity of the geodynamo to generate a poloidal field both the mean dipole moment and its standard deviation appear to be a function of the range of values each cu may adopt at one particular time this range is itself controlled by the variation of the maximum limit of dipole moment while the value of the minimum limit remains relatively constant tentative support is provided for the recent suggestion that psv may have been reduced during the cretaceous normal superchron cns though more data are needed in the range 120 60 ma to confirm this no conclusive evidence was found to support the suggestion that the gpfi record may be biased towards low or high values by palaeointensity determinations obtained using methods that do not adopt ptrm checks indeed offsets caused by unreliable data in well represented parts of the record are likely to be random and cancel one another out when gpfi variation is analysed at a sufficiently high resolution to allow comparisons with the geomagnetic polarity reversal frequency rf it is not possible to confirm whether the two parameters are anticorrelated decoupled or related in some more complex way however it is clear that gpfi and rf are definitely not positively correlated as has been previously suggested the present database documents sharp increases in gpfi around the onset times of the two recognized superchrons itself implying an anticorrelation the implications for geodynamo and mantle modelling of both an anticorrelation and a decoupling of the geomagnetic parameters are discussed briefly a generic geodynamic model is proposed to explain the relationship between observed longterm changes in gpfi and global geodynamic processes the model predicts that changes in gpfi result from a chain of geodynamic processes extending from crust to core beginning with plate reorganizations at the surface and culminating in increases in the vigour of outer core convection supercontinents are transient surface expressions of such geodynamic processes and provide the potential to test the generic model four time stages are proposed to describe the major long term changes in gpfi since the early devonian 400 350 350 250 250 175

groundwater flow to a general well configuration in an unconfined aquifer overlying a fractured bedrock abstract unconfined aquifers sometimes overlie fractured bedrocks consisting of unconfined fractured aquifer systems pumping induced hydrodynamics in such aquifer systems has not received much attention as in other types of aquifer systems this paper aims to obtain semi analytical solutions of flow to a general well configuration in such an unconfined fractured two layer aquifer system the examples of general well configuration specifically discussed here include 1 a horizontal well 2 a vertical well 3 a vertical well with one horizontal collector and 4 a vertical well with two horizontal collectors which are perpendicular with each other the methodology is general and can be extended to other types of wells with minor modifications of solutions developed in this study the point sink source solution is first obtained using double infinite fourier and laplace transformations where sink is for pumping and source is for injection the line sink source solution is then obtained via integrating the point sink source along the desired direction and following the principle of superposition the de hoog numerical inverse laplace transform and gaussian quadrature are used to obtain time domain dimensionless drawdown solutions the instantaneous drainage of water table and the inter porosity flow of the underlying fractured aquifer are taken into account the effects of the length of horizontal well on dimensionless drawdown and dimensionless drawdown derivative and scaled sensitivity of the hydraulic parameters of the underlying fractured aquifer are explored the dimensionless drawdowns and drawdown derivatives of a vertical pumping well a vertical well with a single horizontal collector and a vertical well with two perpendicular horizontal collectors are also compared the scaled sensitivity of dimensionless drawdown to the hydraulic parameters of the underlying fractured aquifer of these different pumping well structures is explored the results of this study can be used to evaluate the hydraulic parameters using the drawdown data collected during a pumping test performed in a general well configuration in a unconfined fractured two layer aquifer system furthermore the presented solutions can be utilized to design the pumping well to minimize drawdown in low permeability or thin aquifers by eliminating the inter porosity flow term from the underlying fractured aquifer the solutions are applicable to groundwater flow to a pumping well in leaky aquifers

evaluation of measurement related uncertainties in the analysis of overcoring rock stress data from aspo hrl sweden a case study a re evaluation of overcoring results from the borre probe and the csiro hi cell was carried out at the aspo hrl the re analysis revealed a number of measurement related uncertainties for the two cells e g bonding temperature effects and identification of elastic parameters these uncertainties were corrected and the re analyzed strains were then used to determine the in situ stress field using standard least squares technique the results indicate lower stress magnitudes compared to the original interpretations and the results are in good agreement with existing hydraulic fracturing data as well as with theoretical vertical stress overall the re analysis indicates that the stress field at aspo hrl is well constrained and relatively consistent with depth

measurement related uncertainties in overcoring data at the aspo hrl sweden part 2 biaxial tests of csiro hi overcore samples this paper is the second dealing with measurement related uncertainties of overcoring data undertaken at the aspo hard rock laboratory and focuses on the biaxial test data from csiro hi overcore sa

illawarra reversal the fingerprint of a superplume that triggered pangean breakup and the end guadalupian permian mass extinction abstract the permian magnetostratigraphic record demonstrates that a remarkable change in geomagnetism occurred in the late guadalupian middle permian ca 265 ma from the long term stable kiaman reverse superchron throughout the late carboniferous and early middle permian to the permian triassic mixed superchron with frequent polarity changes in the late permian and triassic this unique episode called the illawarra reversal probably reflects a significant change in the geodynamo in the outer core of the planet after a 50 million years of stable geomagnetism the illawarra reversal was likely led by the appearance of a thermal instability at the 2900 km deep core mantle boundary in connection with mantle superplume activity the illawarra reversal and the guadalupian lopingian boundary event record the significant transition processes from the paleozoic to mesozoic modern world one of the major global environmental changes in the phanerozoic occurred almost simultaneously in the latest guadalupian as recorded in 1 mass extinction 2 ocean redox change 3 sharp isotopic excursions c and sr 4 sea level drop and 5 plume related volcanism in addition to the claimed possible links between the above listed environmental changes and mantle superplume activity i propose here an extra explanation that a change in the core s geodynamo may have played an important role in determining the course of the earth s surface climate and biotic extinction evolution when a superplume is launched from the core mantle boundary the resultant thermal instability makes the geodynamo s dipole of the outer core unstable and lowers the geomagnetic intensity being modulated by the geo and heliomagnetism the galactic cosmic ray flux into the earth s atmosphere changes with time the more cosmic rays penetrate through the atmosphere the more clouds develop to increase the albedo thus enhancing cooling of the earth s surface the illawarra reversal the kamura cooling event and other unique geologic phenomena in the late guadalupian are all concordantly explained as consequences of the superplume activity that initially triggered the breakup of pangea the secular change in cosmic radiation may explain not only the extinction related global climatic changes in the end guadalupian but also the long term global warming cooling trend in earth s history in terms of cloud coverage over the planet

an examination of in situ rock stress estimation using the kaiser effect abstract when rock cores are loaded in uniaxial compression acoustic emission occurs when the stress reaches a level greater than that which the rock has previously experienced this phenomenon known as the kaiser effect has been used as an indirect method of estimating the in situ stress field in rock masses if the procedure is valid then the kaiser effect method has the advantage that the stress field can be estimated through laboratory tests on rock cores rather than the field drillhole methods of overcoring and hydraulic fracturing however the kaiser effect method is an enigma on the one hand there are good reasons why the method cannot be valid on the other hand there are reports in the literature of it being successfully applied in this paper we explore the variety of geological and mechanical factors involved and report on a case example for the olkiluoto crystalline rock site in western finland we conclude that the kaiser effect method for stress measurement is only likely to be successful if it is supported by key geological and other stress measurement information and if certain procedures are followed as explained in the paper

analysis of pumping induced unsaturated regions beneath a perennial river 1 the presence of an unsaturated region beneath a streambed during groundwater pumping near streams can reduce the pumping capacity change flow paths and alter the types of biological transformations in the streambed sediments a three dimensional multiphase flow model of two horizontal collector wells along the russian river near forestville california was developed to investigate the impact of varying the ratio of the aquifer to streambed permeability on 1 the formation of an unsaturated region beneath the stream 2 the pumping capacity 3 stream water fluxes through the streambed and 4 stream water traveltimes to the collector wells the aquifer to streambed permeability ratio at which the unsaturated region was initially observed ranged from 10 to 100 the size of the unsaturated region beneath the streambed increased as the aquifer to streambed permeability ratio increased the simulations also indicated that for a particular aquifer permeability decreasing the streambed permeability by only a factor of 2 3 from the permeability where desaturation initially occurred resulted in reducing the pumping capacity in some cases the stream water fluxes increased as the streambed permeability decreased however the stream water residence times increased and the fraction of stream water that reached that the wells decreased as the streambed permeability decreased indicating that a higher streambed flux does not necessarily correlate to greater recharge of stream water around the wells

in situ stress measurements and regional stress field assessment of the beishan area china abstract knowledge of the in situ stress field in the rock mass at depth is important to provide stress boundary conditions for underground excavation design stability evaluation and the optimization of ground support systems in the present study in situ stress measurement using hydraulic fracturing method is conducted in the beishan area in gansu province china a preferred candidate site for china s high level radioactive waste repository information on the stress magnitudes and orientations in three sub areas is obtained from 136 measurement points in nine sub vertical boreholes at depths ranging from 30 to 700 m and the distribution characteristics of the in situ stress field is analyzed the pressure time records obtained from the test intervals with pre existing fractures are discussed according to the acoustic borehole televiewer bhtv images the measurement results indicate that the regional stress field is dominated by horizontal stress within most of the measurement depth ranges a piecewise distribution of the principal stresses reveals approximately three stress domains with increasing depth at shallow and medium depths the stress fields are characterized by h h v and h v h respectively where h h and v are maximum horizontal minimum horizontal and vertical stresses respectively with further increase of depth the maximum principal stress changes from horizontal to vertical i e v h h fracture impression results reveal that the maximum horizontal stress is dominantly oriented in the nne nee direction which is in agreement with the orientation of regional tectonic stress field generated from movement of the earth s tectonic plates in addition it is found that the orientations of h are affected by the geological structures significantly

integrating borehole breakout dimensions strength criteria and leak off test results to constrain the state of stress across the chelungpu fault taiwan article the paper describes the computation of the maximum horizontal stress h magnitude in the vicinity of the chelungpu fault taiwan host of the slip zone during the chi chi earthquake mw 7 6 1999 the scientific hole b intercepts the chelungpu fault at 1136 m at the depths of logged breakouts 940 1310 m the vertical stress v as estimated from density logs increases linearly with depth from 22 to 31 mpa a series of leak off tests yielded two reliable shut in pressures 23 7 mpa at 1085 m and 29 8 mpa at 1279 m which are lower than the estimated v albeit by only 2 1 and 0 6 mpa respectively in our analysis the shut in pressures were considered to represent estimates of the least horizontal principal stresses h at the respective depths and consequently the test induced fractures were assumed to have been vertical principal stress directions had been previously determined by others 105 155 for the maximum horizontal stress h

end guadalupian extinction of the permian gigantic bivalve alatoconchidae end of gigantism in tropical seas by cooling abstract the unique permian bivalve family alatoconchidae has aberrant shell forms and extraordinary size up to 1 m representing the largest bivalve group in the paleozoic their occurrence is reported sporadically from lower middle permian shallow marine carbonates in 9 areas in the world tunisia croatia oman iran afghanistan thailand malaysia the philippines and japan that cover low latitudes of both the tethyan and panthalassan domains alatoconchids almost always occurred in close association with large tested fusulines verbeekinidae and or rugose corals waagenophyllidae of the typical tethyan assemblage suggesting their preferential adaptation to shallow warm water tropical environments this tropical trio alatoconchidae verbeekinidae and waagenophyllidae became extinct either during the late guadalupian or around the guadalupian lopingian boundary g lb their intimate association and occurrence range suggest that these 3 taxonomically distinct clades may have shared not only a common habit but also a common cause of extinction the shell structure of alatoconchids suggests their symbiosis with photosynthetic organisms algae cyanobacteria in order to maintain their large body size that required high energy consuming metabolism in contrast to smaller forms the alatoconchidae attained their largest size in the wordian middle guadalupian probably maximizing the benefits of photosymbiosis the subsequent extinction of the warm water adapted tropical trio both in tethys and panthalassa positively supports the explanation that a critical cooling took place on a global scale including low latitude oceans the end of the gigantism in fusulines and bivalves in the capitanian late guadalupian was likely caused by the collapse of photosymbiotic systems during a temporary temperature drop of seawater kamura cooling event coupled with eutrophication that was detrimental to the tropical fauna adapted particularly to oligotrophic conditions gigantism of bivalves occurred several times in the phanerozoic e g siluro devonian permian triassic early jurassic and jurassic creataceous mostly in warm periods the sea level change in the phanerozoic apparently synchronized with the intermittent rise and decline of bivalve gigantism suggesting that the photosymbiosis related gigantism in low latitudes may serve as a potential monitor of global warming cooling in the past

an analytical solution for a radial collector well near a stream with a low permeability streambed summary radial collector wells are often constructed near a stream to obtain more water and produce smaller drawdown in comparison with traditional vertical wells this paper aims at developing a mathematical model for describing head distributions induced by pumping in a radial collector well near a stream in an unconfined aquifer a low permeable streambed between the stream and the aquifer is considered the first order free surface equation is used to describe the movement of water table a point sink solution of the model is developed first by a general transform combining fourier sine and cosine transforms and then by fourier transform and laplace transform the transient solution of head distributions for different well types such as the horizontal well or radial collector well can be obtained by integrating the point sink solution along the well based on darcy s law and the developed solution an equation for temporal stream depletion rate describing filtration from the stream is then obtained the steady state solutions for filtration can be obtained from the transient solution when neglecting the exponential term associated with time it is found that steady state filtration depends only on the ratio of streambed permeability over aquifer permeability steady state filtration equals water extraction from a well when the ratio is larger than 10 2 the streambed is regarded as completely impermeable when the ratio is less than 10 7 additionally the lowest water table happens near the well before occurrence of filtration the lowest water table moves landward and away from the well after filtration occurs

basaltic accumulation instability and chaotic plate motion in the earliest mantle inferred from numerical experiments 1 a series of self consistent numerical models of mantle convection with magmatism and moving plates are presented to clarify the dynamics of the strongly heated mantle of the earliest earth broad hot accumulations of subducted basaltic crusts develop on the core mantle boundary and remain there for geologic time only when the internal heating rate is below a threshold above the threshold the basaltic accumulations become unstable instead the thermal buoyancy induced by the strong internal heating repeatedly causes a massive upwelling or burst of hot materials from deep mantle the mantle burst induces vigorous magmatic activity on the surface the magmatic activity in turn damages the lithosphere and disintegrates it into smaller fragments in contrast to the well ordered plate motion observed below the threshold the lithospheric fragments chaotically move and new subduction zones sporadically develop the mantle burst and chaotic motion of lithospheric fragments effectively stir the mantle and the mantle remains chemically rather homogeneous in spite of the chemical differentiation due to the vigorous magmatism the earth s mantle convection has probably changed its regime from one dominated by frequent mantle bursts and chaotic motion of lithospheric fragments to one dominated by stable basaltic accumulations and well ordered plate motion as the internal heat source decays the suggested regime transition fits in with the earth s tectonic evolution inferred from geologic observations of the continents of various ages

analysis of borehole televiewer measurements in the vorotilov drillhole russia first results abstract in the eurasian part of the world stress map almost the whole region east of the tornquist teisseyre line is terra incognita the closure of this information gap is of fundamental importance to the understanding of the geodynamics of the eurasian continent a detailed analysis of stress induced wellbore breakouts has been performed over a 4 1 km long depth interval in the vorotilov drillhole vgs the borehole is located in the central part of the russian platform right in the center of the vorotilov meteorite impact crater 60 km to the nne of the city of nizni novgorod an ultrasonic borehole televiewer bhtv was used to obtain high resolution acoustical images from the borehole wall with an interactive system for analyzing bhtv data the azimuth and shape of borehole breakouts occurring in the depth range of 1 3 4 8 km were analyzed a statistical analysis of the resulting orientation profile of the breakout azimuths yields an overall direction of the maximum horizontal principal stress s h of n 137 e 15 variations of breakout orientation with depth ranging from a few degrees up to more than 90 are seen on various depth scales the observed stress direction of n 137 e agrees very well with the average s h orientation of n 145 e in central europe if this measurement is taken as representative for the russian platform the stress field in russia is only slightly rotated in comparison to central europe this can possibly be interpreted as indicative for the stress field to be governed by broad scale tectonic forces such as a strong contribution from the forces exerted by the collision zone in the alpine himalayan belt and by the mid atlantic ridge

core disking and its relationship with stress magnitude for lac du bonnet granite abstract core disking is an indicator of elevated stress magnitudes disked cores from boreholes drilled from underground excavations in massive unfractured granite where the stress magnitudes are known with confidence were used to establish a relationship between core disk thickness and the stress magnitude relationships were established for three disk thickness categories 1 thin t d 0 2 2 medium 0 2 t d 0 4 and 3 thick 0 4 t d 2 2 and partial disking the data suggests that core disking initiates when the maximum principal stress normalized to the tensile strength is 6 5

variation of in situ stress regime in coal reservoirs eastern yunnan region south china implications for coalbed methane production knowledge of in situ stress distribution is fundamental for coalbed methane production however it is poorly understood in the eastern yunnan region south china in this study the horizontal maximum shmax and minimum shmin principal stress and vertical stress sv were systematically analyzed for the first time the results indicated that the magnitudes of shmax shmin and sv showed positive correlations with burial depth in general three types of in situ stress fields were determined 1 shmax sv shmin in shallow layers with burial depths less than approximately 600 m 1970 ft below ground level bgl indicating a dominant strike slip faulting stress regime 2 in medium layers approximately 600 800 m 1970 2625 ft bgl the in situ stress state followed multiple relationships suggesting that the in situ stress regime was transformed and 3 sv shmax shmin in deep layers with burial depths greater than approximately 800 m 2625 ft bgl indicating a dominant normal faulting stress regime coal permeabilities obtained from injection falloff well tests showed that they were widely distributed and no obvious relationships were found between coal permeability and effective in situ stress magnitude in the study area the development and orientation of previously generated natural fractures combined with the present day in situ stress distribution controlled the permeability in coal reservoirs differential stress and presence of natural fractures significantly affected the geometry and pattern of hydraulic fractures in addition in the eastern yunnan region locations with relatively deep depths in vertical wells and approximately west northwest east southeast trending horizontal wells suffered high potential of borehole instability because of the high differential stress

superplumes plates and mantle magmatism in two dimensional numerical models 1 two dimensional numerical models are systematically presented for magmatism in a convecting mantle internally heated by incompatible radioactive elements plate tectonics is self consistently modeled as a part of convection of newtonian fluid with temperature and stress history dependent viscosity driven by thermal and compositional buoyancy while magmatism is modeled as an upward migration of basaltic magma generated by decompression melting ridge magmatism actively takes place to chemically differentiate the mantle and a superplume is well developed in the lowermost mantle as a broad hot region enriched in basaltic component provided that the lithosphere is mechanically strong enough to inhibit spontaneous initiation of subduction by its own weight and that the internal heating rate is sufficiently high hot narrow plumes frequently rise up from the superplume to induce deep magma generation and hot spot magmatism which in turn frequently induces new plate margins the frequent plate margin formation keeps the activity of plate tectonics rather steady the thermal and chemical state of the mantle remains rather steady too as the internal heating rate becomes lower however the narrow plumes from superplume become sporadic and significantly colder deep magma generation becomes rare and new plate margin formation becomes less frequent as a consequence the activity of plate tectonics and the thermal and chemical state of the mantle become fluctuating much with time the mantle structure and plume behavior modeled here match with many observations for those of the earth from the archean to the present

low geomagnetic field intensity during the kiaman superchron thellier and microwave results from the great whin sill intrusive complex northern united kingdom 1 coe modified thellier cmt and microwave mw paleointensity experiments were conducted on samples from the multi phase late carboniferous ca 301 ma to early permian ca 270 ma great whin sill complex statistically comparable results were obtained with both techniques from high quality data forty three samples 25 with cmt and 18 with mw yielded mean paleointensity values of 12 0 5 8 t and 16 5 8 2 t for the early and late intrusive phases respectively corresponding to vdms of 1 6 0 8 1022 and 2 1 1 1 1022 am2 when combined with previous data the results suggest a generally low dipole moment during the krs reducing from 75 of the present value at 301 ma to 20 27 of the present value later in the superchron these data imply either a decoupling between processes controlling reversal rate and field strength or a more complex intriguing time lag relationship more absolute palaeointensity results are needed to further evaluate these alternatives

3d geomechanical modeling and numerical simulation of in situ stress fields in shale reservoirs a case study of the lower cambrian niutitang formation in the cen gong block south china abstract an analysis of the in situ state of stress in a shale reservoir was performed based on comprehensive information about the subsurface properties from wellbores established during the development of an oil and gas field industrial level shale gas production has occurred in the niutitang formation of the lower cambrian cen gong block south china in this study data obtained from hydraulic fracturing drilling induced fractures borehole breakout global positioning system gps and well deviation statistics have been used to determine the orientation of the maximum horizontal principal stress additionally hydraulic fracturing and multi pole array acoustic logging xmac were used to determine the vertical variations in the in situ stress magnitude based on logging interpretation and mechanical experiments the spatial distributions of mechanical parameters were obtained by seismic inversion and a 3d heterogeneous geomechanical model was established using a finite element stress analysis approach to simulate the in situ stress fields the effects of depth faults rock mechanics and layer variations on the principal stresses horizontal stress difference horizontal stress difference coefficient k h and stress type coefficient s p were determined the results show that the direction of the maximum principal stress is ese 120 additionally the development zones of natural fractures appear to correlate with regions with high principal stress differences at depths shallower than 375 m the stress type is mainly a thrust faulting stress regime at depths ranging from 375 to 950 m the stress type is mainly a strike slip faulting stress regime when the depth is 950 m the stress type is mainly a normal faulting stress regime depth fault orientation and rock mechanics all affect the type of stress the knowledge regarding the cen gong block is reliable and can improve borehole stability casing set point determination well deployment optimization and fracturing area selection

the kiaman reversed polarity superchron at kiama toward a field strength estimate based on single silicate crystals abstract we present the first geomagnetic paleointensity measurements on single plagioclase crystals from lavas formed during the 262 318 ma permo carboniferous reverse polarity superchron commonly known as the kiaman rock magnetic experiments suggest that feldspar crystals separated from two lavas of the kiaman superchron type area near kiama australia carry pseudo single domain low ti magnetic inclusions capable of faithfully retaining a primary paleointensity signal thellier paleointensity experiments yield virtual dipole moments of 8 5 0 2 1022 am2 and 9 3 0 3 1022 am2 for these crystals furthermore these results lack the alteration problems that prohibit paleointensity and sometimes paleodirection determination using whole rock lava samples from the type area the derived field strengths are 5 6 times higher than some other virtual dipole moment vdm values of kiaman age derived from whole rock igneous samples this suggests either high paleointensity variability during the kiaman superchron or that unrecognized non ideal magnetic behavior has compromised some prior paleointensity results reported from whole rocks elsewhere

semi analytical solutions of discharge variation of a qanat in an unconfined aquifer subjected to general areal recharge and nearby pumping well discharge abstract qanat is a type of drain that extract water from aquifers by gravity significant amount of fresh water used in middle east and other parts of the world are supplied by qanats despite their importance discharge variation of these type of wells received almost no attention the aim of this research is to obtain a laplace domain solution of discharge variation of a qanat installed in an anisotropic unconfined aquifer subjected to arbitrary areal recharge and nearby pumping well s discharge a new semi analytical solution of drawdown is obtained first to implement the effects of arbitrary areal recharge and nearby pumping well s using the principle of superposition then the discharge variation solution of the qanat is obtained from the drawdown solution to establish a constant head boundary condition at the qanat periphery the qanat is discretized into several segments the results of this study are presented in dimensionless discharge dimensionless time curves the effects of hydraulic as well as geometric parameters on the discharge variation of the qanat due to arbitrary areal recharge falling of water table from its initial position and discharge of nearby wells are explored we also investigate the influences of distance and screen depth and location of the nearby well on the discharge variation of the qanat the results of this study can be utilized for multiple purposes 1 to predict discharge of qanat in response to rainfall and nearby pumping well s 2 to estimate the aquifer parameters using hydrograph of the qanat 3 to determine optimal location and pumping pattern of the nearby wells to minimize their influences on the discharge of the qanat 4 to calculate water budget of aquifers drained by a qanat the equation presented in this work can also be used to estimate discharge of a horizontal drain installed in cropland subjected to arbitrary irrigation pattern

well bore breakouts and in situ stress the detailed cross sectional shape of stress induced well bore breakouts has been studied using specially processed ultrasonic borehole televiewer data we show breakout shapes for a variety of rock types and introduce a simple elastic failure model which explains many features of the observations both the observations and calculations indicate that the breakouts define relatively broad and flat curvilinear surfaces which enlarge the borehole in the direction of minimum horizontal compression this work supports the hypothesis that breakouts result from shear failure of the rock where the compressive stress concentration around the well bore is greatest and that breakouts can be used to determine the orientation of the horizontal principal stresses in situ

uncertainty in the maximum principal stress estimated from hydraulic fracturing measurements due to the presence of the induced fracture the classical theory for hydraulic fracturing stress measurements assumes an ideal case with a linear elastic homogenous and isotropic medium and a fracture that reopens distinctly when the minimum tangential borehole stress is exceeded the induced fracture disturbs this ideal picture in several aspects which are important for the evaluation of the maximum horizontal principal stress using the fracture reopening pressure this disturbance can be attributed to the fracture normal stiffness and the initial hydraulic fracture permeability in this paper the hydraulic fracturing reopening test is studied by coupled hydromechanical modeling that takes into account an induced fracture that is incompletely closed the result shows that with realistic equipment compliance the apparent fracture reopening evaluated from the well pressure is close to the magnitude of the minimum horizontal principal stress with little or no correlation to the maximum horizontal principal stress this observation suggests that the determination of maximum principal stress by hydraulic fracturing using the reopening pressure is very uncertain

an overview of rock stress measurement methods this paper presents an overview of methods that have been used to estimate the state of stress in rock masses with the emphasis on methods applicable to hard rocks and scandinavia rock stress is a difficult quantity to estimate because the rock stress measuring techniques consist of perturbing the rock measuring displacements or hydraulic parameters and converting the measured quantities into rock stresses there are two main types of method those that disturb the in situ rock conditions i e by inducing strains deformations or crack opening pressures and those that are based on observation of rock behaviour without any major influence from the measuring method the most common methods are briefly described including their application areas and limiting factors

volcanism mass extinction and carbon isotope fluctuations in the middle permian of china the 260 million year old emeishan volcanic province of southwest china overlies and is interbedded with middle permian carbonates that contain a record of the guadalupian mass extinction sections in the region thus provide an opportunity to directly monitor the relative timing of extinction and volcanism within the same locations these show that the onset of volcanism was marked by both large phreatomagmatic eruptions and extinctions amongst fusulinacean foraminifers and calcareous algae the temporal coincidence of these two phenomena supports the idea of a cause and effect relationship the crisis predates the onset of a major negative carbon isotope excursion that points to subsequent severe disturbance of the ocean atmosphere carbon cycle

fusuline biotic turnover across the guadalupian lopingian middle upper permian boundary in mid oceanic carbonate buildups biostratigraphy of accreted limestone in japan abstract two sections in upper middle to lower upper permian shallow water limestones at kamura and akasaka in southwest japan were analyzed for detailed lithostratigraphy and biostratigraphy both sections represent ancient seamount capping carbonate buildups developed on a basaltic basement in a mid oceanic environment the occurrence of abundant tethyan fusulines allows the recognition of well defined biostratigraphic zonation in both sections and their mutual correlation the upper guadalupian middle permian lepidolina yabeina zone is overlain conformably by the lower lopingian upper permian codonofusiella reichelina zone with a 13 m thick transitional interval barren of index taxa the guadalupian lopingian g l boundary is marked by the first appearance datum fad of the lopingian codonofusiella reichelina assemblage in both sections this study recognizes for the first time the g l boundary horizon in a mid oceanic shallow water environment in addition the shallow water carbonates in the study sections record the extinction of the middle permian large sized fusuline family verbeekinidae at the g l boundary in mid panthalassa as well as in shallow water tethyan shelf areas demonstrating positively that the g l boundary mass extinction occurred on a global scale the abrupt elimination of large shelled fusulines followed by the domination of small shelled fusulines may indicate that environmental stress occurred at the end of guadalupian the dying out of symbiotic algae may have caused the selective extinction of the large shelled fusulines

permian carboniferous and permian triassic magmatism in the rift zone bordering the tethyan margin of southern pangea magma was emplaced in the india australia rift zone along the tethyan margin during permian carboniferous and permian triassic time permian carboniferous alkalic granite and basaltic and rhyolitic lava flows and tuffs formed at the same time as right lateral transtension of pangea as recorded by the magmatic rocks of neocratonic post variscan europe and post kanimblan eastern australia permian triassic tholeiitic basalt in india alkalic magmatic rocks in oman and rhyolite dolerite and undersaturated alkalic volcanic rocks in western australia preceded and accompanied the early opening of the neo tethys ocean coeval magmatism included the voluminous mid plate siberian traps the emeishan basalt of south china and the peak activity of the magmatic arc along the convergent panthalassan margin the background magmatism probably permitted the siberian traps to trigger the environmental catastrophe at the permian triassic boundary

significance of hydraulic head gradients within horizontal wells in unconfined aquifers of limited saturated thickness summary horizontal wells can be used to withdraw water from shallow aquifers frequently there is a substantial hydraulic gradient within the horizontal well this paper considers the significance of the hydraulic head distribution for horizontal wells in shallow aquifers and estimates the inflows of groundwater along the length of the well conceptual and computational models are developed to represent time variant regional groundwater flow convergent flows towards and into the horizontal well and hydraulic conditions within the well are also included a case study of a 300 m long horizontal well curved in plan in an aquifer of limited saturated thickness is used to illustrate the approach field monitoring indicates significant drawdowns in groundwater heads in the vicinity of the well substantial difference in hydraulic head between the pump end and the far end of the well are also identified successful comparisons are made between field and model results from the numerical models groundwater inflows along the well are estimated inflows at the pump end are about four times the inflows towards the far end the effect of reducing the length of the well is explored

a comparative simulation study of coupled thm processes and their effect on fractured rock permeability around nuclear waste repositories this paper presents an international multiple code simulation study of coupled thermal hydrological and mechanical thm processes and their effect on permeability and fluid flow in fractured rock around heated underground nuclear waste emplacement drifts simulations were conducted considering two types of repository settings 1 open emplacement drifts in relatively shallow unsaturated volcanic rock and 2 backfilled emplacement drifts in deeper saturated crystalline rock the results showed that for the two assumed repository settings the dominant mechanism of changes in rock permeability was thermal mechanically induced closure reduced aperture of vertical fractures caused by thermal stress resulting from repository wide heating of the rock mass the magnitude of thermal mechanically induced changes in permeability was more substantial in the case of an emplacement drift located in a relatively shallow low stress environment where the rock is more compliant allowing more substantial fracture closure during thermal stressing however in both of the assumed repository settings in this study the thermal mechanically induced changes in permeability caused relatively small changes in the flow field with most changes occurring in the vicinity of the emplacement drifts

reply to the comment by j r ali on illawarra reversal the fingerprint of a superplume that triggered pangean breakup and the end guadalupian permian mass extinction by yukio isozaki abstract the following four major questions were raised about my recent proposal for the possible link between the end guadalupian extinction and a unique geomagnetic event called the illawarra reversal isozaki 2009a 1 timings of extinction cooling and the illawarra reversal end of the kiaman superchron 2 geomagnetic intensity during superchrons 3 ascent rate of mantle plume and 4 age constraints of lip volcanism in east pangea the latest research results on the permian biodiversity change numerical modeling of plume and single crystal measurement of geomagnetism support that the timings of extinction and the illawarra reversal high field intensity during the kiaman superchron and ascent rate of plume are reasonably explained in accordance with the integrated plume winter scenario isozaki 2009b the onset ages of lip volcanism need further refinement for identifying the impingement of a plume head

base flow recession from unsaturated saturated porous media considering lateral unsaturated discharge and aquifer compressibility unsaturated flow is an important process in baseflow recessions and its effect is rarely investigated a mathematical model for a coupled unsaturated saturated flow in a horizontally unconfined aquifer with time dependent infiltrations is presented the effects of the lateral discharge of the unsaturated zone and aquifer compressibility are specifically taken into consideration semi analytical solutions for hydraulic heads and discharges are derived using laplace transform and cosine transform the solutions are compared with solutions of the linearized boussinesq equation lb solution and the linearized laplace equation ll solution respectively a larger dimensionless constitutive exponent d a smaller retention capacity of the unsaturated zone leads to a smaller discharge during the infiltration period and a larger discharge after the infiltration the lateral discharge of the unsaturated zone is significant when d 1 and becomes negligible when d d 100 the compressibility of the aquifer has a non negligible impact on the discharge at early times for late times the power index b of the recession curve dq dt aqb is 1 and independent of d where q is the baseflow and a is a constant lumped aquifer parameter for early times b is approximately equal to 3 but it approaches infinity when t 0 the present solution is applied to synthetic and field cases the present solution matched the synthetic data better than both the ll and lb solutions with a minimum relative error of 16 for estimate of hydraulic conductivity the present solution was applied to the observed streamflow discharge in iowa and the estimated values of the aquifer parameters were reasonable

a high latitude gondwanan lagerstatte the permian permineralised peat biota of the prince charles mountains antarctica abstract the toploje member chert is a roadian to wordian autochthonous parautochthonous silicified peat preserved within the lambert graben east antarctica it preserves a remarkable sample of terrestrial life from high latitude central gondwana prior to the capitanian mass extinction event from both mega and microfossil evidence that includes cryptic components rarely seen in other fossil assemblages the peat layer is dominated by glossopterid and cordaitalean gymnosperms and contains moderately common herbaceous lycophytes together with a broad array of dispersed organs of ferns and other gymnosperms rare arthropod plant and fungal plant interactions are preserved in detail together with a plethora of fungal morphotypes peronosporomycetes arthropod remains and a diverse coprolite assemblage comparisons to other palaeozoic ecosystems show that the macroflora is of low diversity the fungal and invertebrate plant associations demonstrate that a multitude of ecological interactions were well developed by the middle permian in high latitude forest mires that contributed to the dominant coal deposits of the southern hemisphere quantitative analysis of the constituents of the silicified peat and of macerals within adjacent coal seams reveals that whilst silicified peats provide an unparalleled sample of the organisms forming permian coals they do not necessarily reflect the volumetric proportions of constituents within the derived coal the toploje member chert lagerstatte provides a snapshot of a rapidly entombed mire climax ecosystem in the closing stages of the palaeozoic but prior to the onset of the protracted crisis that engulfed and overthrew these ecosystems at the close of the permian