numerical modelling of sea surface temperature and circulation in the great australian bight abstract the blumberg mellor 3d numerical ocean model was employed to investigate the seasonal cycle of sea surface temperature sst and circulation within the great australian bight gab an idealised representation of the gab was modelled results indicated that a warm water mass could be established within the gab with features comparable to observation due to the application of a positive net heat flux at the surface and forcing from the west to east passage of anticyclonic weather systems these systems had a north south migration representative of the shifting subtropical high pressure ridge over southern australia an anticyclonic gyre was established within the gab as a result of the imposed wind stress which contributed towards the formation of a warm tongue spreading across the gab from west to east and a pool of significantly colder water in the eastern gab the sst distribution was found to be sensitive to the bottom topography and north south gradient of heat flux applied to the model domain intrusion of an external current through the western boundary in winter representing the leeuwin current revealed that warm water associated with the intrusion did not penetrate into the gab to any great distance

a predictive methodology for multi seam mining induced subsidence abstract multi seam longwall mining induced subsidence profiles are often different from those of single seam mining as a result conventional subsidence prediction methods are less reliable for multi seam subsidence predictions in this study significant differences between the single and multi seam subsidence parameters are studied in a multi seam case study in australia results from this case study are employed to establish a characterisation of the multi seam subsidence which is applicable for every multi seam mining configuration the proposed characterisation is then utilised for modification of a conventional influence function method ifm in the modified method namely discrete ifm a mine section is divided into discrete segments with certain subsidence parameters the resultant subsidence of each segment is calculated and then superimposed to achieve the final subsidence profile application of the discrete ifm is demonstrated in an example case study where reliable subsidence predictions are achieved it is illustrated that the discrete ifm offers a flexible approach for consideration of multiple subsidence parameters for different segments which enables this method to predict irregular subsidence profiles

genesis of palimpsest cool water carbonate sediment on the continental margin of southern australia abstract the continental margin of southern australia is a site of extensive quaternary cool water carbonate sedimentation seafloor sediments are a mixture of holocene biofragments and late pleistocene relict and stranded particles relict sediments produced during marine isotope stages 3 and 4 are generally preserved as iron stained intraclasts such grains in the great australian bight are photozoan in character they include symbiont bearing benthic foraminifers and coralline algal particles and indicate that the wide shelves were bathed in shallow relatively warm oligotrophic waters and floored by marine grasses similar to many modern shallow inboard embayments in the region today in contrast east of the great australian bight relict sediments are more heterozoan in character with coralline algal and molluscan facies on the inner shelf and bryozoan sediments on the outer shelf stranded sediments marooned during the sea level rise associated with marine isotope stage 2 are gray to buff in color and composed of both biofragments and intraclasts these particles are mainly heterozoan in character throughout the region with subtropical photozoan marine grassbank facies localized to portions of the inner great australian bight stranded sediments are interpreted to have accumulated in an areally restricted photic zone and upon an overall narrow shelf covered in cool nutrient rich waters swell driven seafloor sediment disturbance to depths of 100 m along the southern australian margin in conjunction with reduced rates of sedimentation that characterize the cool water carbonate realm have resulted in mixing of sediment currently being produced with exhumed relict and stranded sediments generated during previous sea level stands the composition of these deposits and the nature of their pre burial alteration are a function of sea level history late pleistocene relict sediments originally accumulated in low energy inboard environments but were modified in the surf zone during subsequent sea level fluctuations this resulted in the formation of intraclasts abraded infilled and cemented biofragments of local origin the widespread distribution of intraclasts and of composite grain assemblages derived from multiple sedimentary environments that display highly variable degrees of seafloor alteration may be signatures of modern cool water carbonate assemblages worldwide while such palimpsest sediments may complicate paleoenvironmental interpretation their differentiation in the rock record can be utilized to discern subtleties in paleoceanography and sea level history

investigation of karst collapse based on 3 d seismic technique and dda method at xieqiao coal mine china abstract karst collapse is a serious geological problem in most of the coal mines in the north of china but recently it has been found in the south as well the present study is aimed at investigating subsidence mechanism and deformation field of a karst collapse column at xieqiao in the south of china a method of three dimensional 3 d seismic technique has been successful in exploring the spatial morphology of the karst collapse at xieqiao and the discontinuous deformation analysis dda method is used to calculate the deformation field and analyze the subsidence mechanism the results indicated that dda could approximately simulate and back analyze the subsidence process and strata deformation fields the subsidence processes of the collapse column depend on the sizes of the karst caves with the continuous expansion of the karst caves a semi elliptic stress field local separation strata and fracture zone will be formed around the karst cave moreover they will gradually expand upwards along the vertical direction the paper also indicates that the subsidence failure stage may trigger a sudden collapse of the karst column because of the sudden energy release also it will make a great impact on the vicinity working face so as to cause a rock burst the effects of the friction angle of rock strata on the subsidence mechanism were reported firstly based on dda

extraction algorithm of mining subsidence information on water area based on support vector machine information on subsidence in a water area caused by mining has a great value on the research of the mining subsidence law of a mining area with a high groundwater level in eastern china based on the measured data of the subsidence area without water the data extraction of subsidence in a water area is studied in this paper with a support vector machine as subsidence in such an area is difficult to measure research shows that the training sample number and dimension should be strengthened by increasing the measuring times or using the interpolation method to obtain ideal prediction accuracy the e support vector regression model with three parameters optimized by the genetic algorithm or the particle swarm optimization algorithm is suitable to extract subsidence information in a water area caused by mining and the algorithm is accomplished on matlab data analysis showed that when the water is deeper than 1 8 m and the distance is over 60 m from the measured points the prediction error of test samples will exceed 10 out of all measured results meaning that practicability is relatively poor while water depth is 0 8 m or the distance is lower than 60 m from the measured points the prediction error of test samples will be calculated to 5 of the measured results the prediction results can be used

eddy formation through the interaction between the leeuwin current leeuwin undercurrent and topography abstract the surface and subsurface circulation off south west australia was simulated using the regional ocean modelling system roms a primitive equation ocean model with terrain following s coordinates the major currents in this region the leeuwin current and leeuwin undercurrent were reproduced by specifying only temperature and salinity distributions from climatology the application of wind stress subsequent to the model reaching a quasi steady state resulted in the generation of the seasonal capes current a northward flowing current on the continental shelf associated with coastal upwelling the simulated currents compared well with the observed current patterns including the location and maximum current speeds shelf topography variations and bottom shear which generated vorticity influenced eddy formation eddies separated from the leeuwin current and the leeuwin undercurrent migrated westward and exited the model domain through merging dissipating or through an open boundary in the model simulations the undercurrent produced mostly cyclonic eddies due to strong negative vorticity where the current flowed against the continental slope the leeuwin current produced anticyclonic warm core eddies initiated from the formation of meanders which were strongest at the surface the eddy field was dominated by anticyclonic eddies at the surface and cyclonic eddies at 500 m the interaction between the leeuwin current and leeuwin undercurrent led to the formation of eddy pairs

dense shelf water formation along the south west australian inner shelf 1 hydrological data from a repeated cross shore transect obtained using teledyne webb research slocum electric gliders offshore two rocks in south western australia over 13 months are presented the data revealed that formation of dense water inshore and its transport across the shelf as a near bed gravity current defined as dense shelf water cascade dswc was a regular occurrence particularly during autumn and winter months in autumn the dense water is mainly formed through changes in salinity resulting from evaporation whilst in winter temperature change through surface cooling was the dominant factor the mean wind speeds also decrease during the transition during autumn the speed of the dswc was estimated to be 0 01 0 02 m s 1 and similar to that measured in other selected regions globally the offshore transport from the shelf is a significant component of the alongshore wind driven transport

an underground mining detection system based on dinsar underground mining easily causes casualties and illegal mining is a major contributor to this issue it is a challenge to locate and differentiate illegal mines from approved mines over a vast area over the past few years our research in satellite differential radar interferometry dinsar to monitor underground mine induced surface subsidence has demonstrated the reliability of dinsar in this paper a dinsar based illegal mining detection system dimds is proposed to exploit the geometric spatial and temporal characteristics of those subsidence patterns testing results over a coalfield in asia have proven the efficiency reliability and cost effectiveness of dimds in finding out illegal mines

a 6 year record of baroclinic transport variability of the antarctic circumpolar current at 140 e derived from expendable bathythermograph and altimeter measurements 1 repeat hydrographic sections across the antarctic circumpolar current are used to derive an empirical relationship between upper ocean temperature and the baroclinic transport stream function cross validation shows this relationship can be used to infer baroclinic transport above and relative to 2500 dbar from temperature measurements with an error of a few per cent the mean transport distribution derived from 31 austral summer expendable bathythermograph xbt sections over a 6 year period consists of westward flow immediately south of tasmania a broad band of strong eastward flow between 50 and 55 s and three cores of eastward flow south of 55 s by defining a second empirical relationship between surface dynamic height and cumulative transport a continuous time series of baroclinic transport is derived from altimeter measurements of sea surface height transports derived from altimetry in this way agree well with simultaneous in situ estimates root mean square error in net transport is 4 106 m3 s 1 suggesting sea level anomalies largely reflect baroclinic changes above 2500 dbar the 10 day sampling of the altimeter transport time series shows the irregular xbt sampling aliases variability at unresolved timescales the standard deviation of net transport above and relative to 2500 m is 4 3 106 m3 s 1 the variability in net transport is largest 2 7 106 m3 s 1 in the quasi annual band periods of 4 months to 1 5 years slightly smaller 2 3 106 m3 s 1 in the mesoscale band 1 5 years 1 5 106 m3 s 1 changes in transport are correlated with local changes in both wind stress and wind stress curl in the quasi annual and interannual bands but the transport time series is too short to draw significant conclusions

strike slip tectonics and granite petrogenesis transpression is a process that thickens the crust and therefore in obliquely convergent orogens as in normally convergent orogens there is the potential to generate granitic melts individual transcurrent shear zones may not only control the ascent paths siting and emplacement mechanisms of plutons but they may also cause the genesis of the granitoids themselves two contrasting situations are examined in the hercynian shear zones of iberia thickening together with hydrous fluxing along shear zones created intracrustal wet melting of fertile gondwanan sediments to produce syntectonic granites in the northern part of the british caledonides the association of compositionally expanded granitoids with a major mantle component and transcurrent shear zones may be explained by melting of continental crust at the lower limits of crustal transpressional faults detaching into the moho

climatic records over the past 30 ka from temperate australia a synthesis from the oz intimate workgroup temperate australia sits between the heat engine of the tropics and the cold southern ocean encompassing a range of rainfall regimes and falling under the influence of different climatic drivers despite this heterogeneity broad scale trends in climatic and environmental change are evident over the past 30 ka during the early glacial period 30 22 ka and the last glacial maximum 22 18 ka climate was relatively cool across the entire temperate zone and there was an expansion of grasslands and increased fluvial activity in regionally important murray darling basin the temperate region at this time appears to be dominated by expanded sea ice in the southern ocean forcing a northerly shift in the position of the oceanic fronts and a concomitant influx of cold water along the southeast including tasmania and southwest australian coasts the deglacial period 18 12 ka was characterised by glacial recession and eventual disappearance resulting from an increase in temperature deduced from terrestrial records while there is some evidence for climatic reversals e g the antarctic cold reversal in high resolution marine sediment cores through this period the high spatial density of holocene terrestrial records reveals an overall expansion of sclerophyll woodland and rainforest taxa across the temperate region after 12 ka presumably in response to increasing temperature while hydrological records reveal spatially heterogeneous hydro climatic trends patterns after 6 ka suggest higher frequency climatic variability that possibly reflects the onset of large scale climate variability caused by the el nino southern oscillation

the mean summertime circulation along australia s southern shelves a numerical study abstract for the first time a high resolution regional model is developed for the slope and shelf circulation within the great australian bight and for the gulfs region of south australia the results indicate the extent nature and dynamical interaction of a variety of circulation features that are most likely to be important for the region in particular the positive wind stress curl south of australia leads to an equatorward sverdrup transport in the deep ocean westward flinders current along the slope and upwelling of the 600 m deep permanent thermocline the wind stress curl also leads to a seaward topographic sverdrup transport within the wide sloping shelf of the bight and results in an anticyclonic gyre that is intensified off the eyre peninsula and reduced in magnitude by the joint effect of baroclinicity and topographic relief in the western half of the bight the seaward surface ekman and topographic transports are shown to converge with the onshore component of the flinders current lea

pan african granite intrusion in response to tectonic volume changes in a ductile shear zone from northern saudi arabia the ajjaj shear zone of the njad fault system of northwestern saudi arabia was a conduit for pan african 500 700 m y calc alkalic and peralkalic magmas ductility contrasts between the wall rocks and the deformed rocks of the shear zone were responsible for differences in size intrusion mechanism and degree of deformation of the granites a quantitative strain analysis across the ajjaj shear zone reveals a finite oblique strike slip displacement of 60 pm 20 km with a vertical displacement component of 5 pm 1 5 km granite diapirs were intruded within the region of volume gain between 83 90 of the volume of the ash sha b diapir was produced by expansion of the granite changes in late pan african granite magmatism especially abrupt variations in alkalic granite distribution can be indirectly linked with the vertical displacement components of the crustal blocks flanking the ajjaj shear belt

simulation of shelf averaged water properties with application to the south coast of australia abstract a method for simulating shelf averaged properties for vertically well mixed water on a strip of continental shelf is presented the conservation equations for temperature and salt are solved making use of air temperatures evaporation and rainfall rates and temperature and salinity data from the adjacent ocean and the ends of the strip together with coastal current transports the transports have been estimated from the longshore variation of wind stress and depth integrated longshore density gradient using a theoretical expression the resulting shelf distributions are interpreted as a summation of signals deriving from processes occurring in specified segments of the strip of continental shelf shelf anomalies the ends of the strip boundary anomalies and from the longshore property variation in the adjacent ocean oceanic anomalies negative oceanic temperature anomalies indicate cool advection which supports upwelling and positive oceanic temperature anomalies warm advection shelf anomalies quantify the modification of water properties on the shelf by meteorological forcing solutions are discussed for the annual cycle along the continental shelf of southern australia in which the importance of advective processes is evident in the salinity distribution but is masked in the temperature distribution by opposing oceanic and shelf anomalies

magma ponding in the karakoram shear zone ladakh nw india granitic melt migration and pluton emplacement are commonly closely associated with transcurrent shear zones the processes that link granites to shear zones are not yet fully understood the dextraltranspressive karakoram shear zone in ladakh nw india exposes anatectic rocks where synkinematic melt migration and ponding at kilometer scale were controlled by competency contrasts metasedimentary rocks and a dominantly granodioritic calcalkaline intrusion underwent fl uid present partial melting at upper amphibolite facies to produce leucogranite sheets and irregular intrusive masses dated at 21 14 ma leucogranitic magmas ponded in the lowpressure strain shadow of the competent grano dioritic calc alkaline pluton giving rise to a migmatitic rocks that are pervaded by irregular leucogranite intrusions at a scale of meters or tens of meters and b the growth of the tangtse pluton a kilometer scale sheeted complex thus magmas accumulated during shearing and anatexis in a low pressure strain shadow within the karakoram shear zone this magma provided a readily available magma source that could have been tapped to feed larger plutons at shallower levels by modifi cations in the pressure distribution accompanying changes in shear zone geometry and kinematics we conclude that shear zones tapping anatectic regions act as magma pumps creating and destroying magma traps at depth as they evolve and leading to incremental magma addition to upper crustal plutons

a northern boundary current along australia s southern shelves the flinders current 1 south of australia the monthly mean wind stress curl is positive during both summer and winter and leads to ekman pumping and downwelling throughout the region sverdrup dynamics indicates that this downwelling should lead to a northward transport of around 5 10 sv 1 sv 10 m3 s 1 classical arguments for western boundary currents are adapted to show that this transport should be deflected into an upwelling favorable boundary current that flows from east to west along australia s southern shelves the flinders current support for this proposition is obtained from results of the ocean circulation and climate advanced modelling project occam sverdrup transports and limited observations for the region in addition the occam results show that the northward transport leads to upwelling at depths below 400 m and that the flinders current 1 intensifies from victoria to western australia transport 8 sv with speeds up to 15 cm s 1 2 can extend from the surface to depths of 800 m and 3 is found during both summer and winter during winter the winds are downwelling favorable and lead to a coastal current that flows from west to east and opposes the flinders current further support for the origin and nature of the flinders current is obtained from simple numerical experiments made using a rectangular domain and idealized representations of the summer and winter wind stress

prediction of ground subsidence in samcheok city korea using artificial neural networks and gis this study shows the construction of a hazard map for presumptive ground subsidence around abandoned underground coal mines aucms at samcheok city in korea using an artificial neural network with a geographic information system gis to evaluate the factors governing ground subsidence an image database was constructed from a topographical map geological map mining tunnel map global positioning system gps data land use map digital elevation model dem data and borehole data an attribute database was also constructed by employing field investigations and reinforcement working reports for the existing ground subsidence areas at the study site seven major factors controlling ground subsidence were determined from the probability analysis of the existing ground subsidence area depth of drift from the mining tunnel map dem and slope gradient obtained from the topographical map groundwater level and permeability from borehole data geology and land use these factors were employed by with artificial neural networks to analyze ground subsidence hazard each factor s weight was determined by the back propagation training method then the ground subsidence hazard indices were calculated using the trained back propagation weights and the ground subsidence hazard map was created by gis ground subsidence locations were used to verify results of the ground subsidence hazard map and the verification results showed 96 06 accuracy the verification results exhibited sufficient agreement between the presumptive hazard map and the existing data on ground subsidence area

study of automated top coal caving in extra thick coal seams using the continuum discontinuum element method abstract in order to investigate top coal drawing regularity and automated top coal caving technology in extra thick coal seams an approach coupling the particle element and the block element is presented based on the continuum discontinuum element method cdem then the constitutive model of hydraulic support is introduced into the cdem to simulate the top coal drawing process meanwhile the bergmark roos model for coal drawing of single support is extended into the collaborative coal drawing of multiple supports to optimize the automated top coal caving technology finally cdem models of hydraulic support armored face conveyer and coal rock strata are established according to the field conditions of the tongxin coal mine then the top coal drawing mechanism is analyzed and an automated top coal caving technology is proposed the results show that under the interaction between hydraulic support and surrounding rocks the final drawing body of initial top coal drawing appears as an irregular deflected ellipsoid shape during different support moving cycles the coal rock structure affects the coal drawing amount and support resistance a statistical comparison of the coal rock drawing amount based on 100 drawing openings indicates that the standard deviation of the coal drawing amount in automated one round coal caving is 1 83 m2 less than that in traditional coal caving 8 23 m2 and the coal drawing amount from each drawing window is more uniform for multi round coal caving techniques the average recovery rate remains at 79 4 and the rock mixed rate is less than 1 based on a comparison of several coal caving techniques automated four round coal caving technology is the optimal technology in which the change rate of the standard deviation of the coal drawing amount as well as the top coal recovery rate are both largest

early diagenesis of carbonates on a cool water carbonate shelf southern australia abstract the southern australian continental margin is an immense cool water carbonate factory the high energy open shelf is blanketed by heterozoan carbonates of both holocene and late pleistocene age three distinct grain types have been identified and radiocarbon dated these include 1 relict grains highly abraded iron stained intraclasts formed during the intermediate sea level stands of marine isotope stages 3 and 4 2 stranded grains gray and buff colored abraded biofragments and intraclasts marooned during the sea level rise associated with marine isotope stage 2 and 3 holocene grains unaltered biofragments formed during marine isotope stage 1 optical mineralogical and chemical characterization of grains of each age has revealed pathways of early diagenesis in this realm both calcitic and aragonite biogenic grains undergo dissolution while dissolution of calcitic components is minor and incomplete relict sediments are predominantly mg calcite aragonitic skeletons undergo significant dissolution within 30 000 years in contrast to early dissolution of aragonite micritic calcite cement with 12 mol mgco3 is a significant diagenetic phase in these sediments infilling many stranded and most relict skeletons similar cement precipitates between grains forming small numbers of cemented grain aggregates in most samples microprobe and icp ms analysis demonstrates fe oxides mn oxides and associated clay minerals discolor stranded and relict grains by coating grain surfaces and infesting micropores such coatings begin to form on holocene grains during or soon after formation the oxides scavenge trace elements including v ti cr and ree altering the elemental compositions of biogenic carbonate

an extension of the insar based probability integral method and its application for predicting 3 d mining induced displacements under different extraction conditions underground extraction can be roughly classified into three types i e subcritical critical and supercritical extraction in accordance with the geological conditions in the overburden and the geometry of mined out areas in 2016 we proposed an approach based on the interferometric synthetic aperture radar insar technique and the probability integral method pim for the cost effective prediction of 3 d mining induced displacements abbreviated as insar pim due to the inherent assumption of critical extraction in the pim the insar pim method performs well in predicting the 3 d displacements caused by critical and or supercritical extraction but poorly for subcritical extraction in this paper we first propose a generalized pim gpim by modifying the traditional pim with a simplified boltzmann function we then replace the pim of the insar pim with the proposed gpim to develop an extension of insar pim referred as to insar gpim the insar gpim was tested in the qianyingzi coal mining area china the results show that the insar gpim predicted horizontal and vertical displacements caused by subcritical critical and supercritical extraction agree well with the in situ observations with average root mean square errors of about 0 032 and 0 050 m respectively these accuracies represent improvements of 60 9 and 59 when compared with the accuracies predicted by the insar pim in the horizontal and vertical directions the results indicate that the insar gpim is capable of accurately predicting 3 d mining induced displacements under different extraction conditions i e subcritical critical and supercritical extraction and it performs much better than the insar pim in the case of subcritical extraction it is therefore believed that insar gpim will have a wider scope of applications than the previous insar pim

numerical analysis of the dynamic evolution of mining induced stresses and fractures in multilayered rock strata using continuum based discrete element methods abstract in this study the continuum based discrete element method cdem was adopted to simulate the evolution of mining induced stress and fracturing during roadway tunnelling and mining in multilayered heterogeneous rock strata the cdem integrates the finite element method fem and the discrete element method dem to characterize the mining induced stress evolution the discontinuous fractures separations and caving that occur in the interfaces between multilayered rock strata the maximum tensile stress criterion and the mohr coulomb strength criterion were used to evaluate the tensile and shear failure of the material elements the cdem model for rock strata was constructed by employing image processing and reconstruction approaches using the geometrical and physical parameters that were measured from a real coal mining site the stress evolution and compression deformation of the roof and floor strata were computed to evaluate the criticality of mining induced disasters the constructed model was employed to simulate and analyse the immediate roof collapse immediate floor bulges and the compaction of the collapse blocks as well as the large deformation separation and collapse between the immediate roof and the main roof during coal seam mining it was shown that the proposed method could predict ranges for the caving zone and fracture zone in the rock roofs that were in good agreement with the observation results from the real coal mining site

δ18o and δ13c variability in brachiopods from modern shelf sediments and its utility for understanding complex oceanography southern australian shelf abstract the 18o and 13c values of brachiopod shell calcite are commonly used as proxies for ancient environmental marine conditions and secular changes in ancient ocean chemistry the variability of 18o and 13c across modern shelf settings is however not well documented this study presents 18o and 13c data from 407 holocene 5000 yr bp and living brachiopods collected from 220 sites across 3000 km along australia s southern shelf the largest cool water carbonate shelf in the modern world significant isotopic variability is present in separate specimens at individual sites and across the entire region individual specimens analyzed at multiple shell positions have an isotopic range of values up to 1 3 and 1 9 for 18o and 13c respectively multiple brachiopods at a single site have values that vary as much as 2 1 for 18o and 1 8 for 13c regional variability ranges on the order of 3 6 and 3 4 for 18o and 13c respectively the distribution of intrasite variability can be divided into areas of high and low variability areas characterized by low variability occur in zones of relatively consistent shelf water conditions high variability zones usually correspond to areas of seasonal upwelling onto the shelf and this aspect is interpreted to be the main cause of isotopic variability upwelling waters are cold leading to higher 18o values and are commonly rich in respired dissolved inorganic carbon dic and nutrients promoting active phytoplankton growth and leading to variable 13c values the extensive spatial coverage across this vast latitude parallel region provides a valuable baseline illustrating the isotopic range that could occur in a single layer in the rock record furthermore changes in isotopic signatures measured across stratigraphy might not necessarily reflect secular changes in ocean chemistry but instead could be recording local changes in shelf circulation and upwelling intensity

a comparative study for estimation of wave height using traditional and hybrid soft computing methods the present study developed a wave height prediction model by the recorded climatic data we used 1 year buoy data for training and testing the developed soft computing model models were developed using a novel method based on the support vector machine svm coupled with the firefly algorithm ffa this research work used the ffa for estimating the optimum parameters in addition this work compared the predicted results of svm ffa model to the artificial neural networks anns and genetic programming gp the results indicate that the svm ffa approach attains an improvement in capability of generalization and predictive accuracy in comparison to the gp and ann a thorough statistical analysis was conducted to compare the predictions of three models i e among the svm ffa ann and gp a high r2 value of 0 979 was obtained for the svm ffa predictions further the ann and gp results showed r2 values of 0 524 and 0 525 respectively moreover achieved results indicate that the developed svm ffa model can be used with confidence for future research works on formulating novel models for predictive strategy on wave height the results also show that the new algorithm can learn thousands of times faster than the former popular learning algorithms this study finds that the application of svm ffa is the likely alternative method for estimating the wave height

the 5500 km long boundary flow off western and southern australia 1 the path of the shelf edge flow off southwestern australia is documented using results from satellite altimetry and sea surface temperature sst and a climatogical in situ analysis during austral winter a continuous current is shown to extend from its origin at north west cape to the southern tip of tasmania a distance of 5500 km satellite sst observations and surface buoy tracks confirm the location and continuity of the current trajectory while the leeuwin current is forced by the strong alongshore pressure gradient associated with the meridional portion of the western australian coastal boundary our results suggest that the essentially zonal shelf edge flow along the southern australian coast arises from the setup of coastal sea level by onshore ekman flow driven by the winter westerly wind and possibly a further alongshore pressure gradient the timing of these two different forcing mechanisms means that the west coast pressure gradient delivers the leeuwin current to the south coast just as the winds reverse and are thus able to maintain the eastward passage of the current the shelf edge flow consists of two main water masses a low salinity warm water type of tropical origin associated with the leeuwin current and a high salinity warm water inflow formed on the western end of the great australian bight continental shelf a naming convention is proposed the leeuwin current representing flow from north west cape to the great australian bight gab the south australian current between the eastern gab and western bass strait and the zeehan current off western tasmania

ocean circulation in the great australian bight in an eddy resolving ocean reanalysis the eddy field seasonal and interannual variability abstract the ocean circulation in the great australian bight gab is dominated by the surface intensified leeuwin current lc over the outer continental shelf and the flinders current farther offshore in the gab the lc flows eastwards and varies seasonally with strongest currents of up to 0 8 m s at 130 5 e bringing warm and salty waters as far east as western tasmania the flinders current flows westwards as an undercurrent at depths of around 500 m over the continental slope and at the surface offshore of the lc off the shelf the gab is rich in mesoscale eddies with surface intensified currents of up to 0 4 m s that are coherent over the full water depth getting weaker with depth within deep water eddies isotherms are displaced vertically by up to 200 m eddies in the eastern gab are most energetic in austral winter and spring coincident with the seasonal weakening of the lc the eastern most penetration of gab eddies occurs in austral winter when the lc starts to weaken we hypothesise that the horizontal shear associated with the lc generates eddies in the eastern gab the volume transport of the lc at the head of the gab is typically between 1 and 7 sv with a clear seasonal cycle and the interannual variability of lc transport is up to 2 sv

investigation of non explosive expansion material in roof caving field application abstract effective roof caving plays a significant role in mining safety a spatiotemporal coupling fracturing method using a non explosive expansion material neem is proposed in this paper this method depends on the high fracturing capacity of the neem and a change from vertical charging to inclined charging aimed at producing new free surfaces step by step until the integrity of the entire rock is destroyed from a space time perspective the expansion stress and water adsorption of the neem were studied to determine the optimum stress increase interval and soak time with respect to the space aspect the charging sequence of boreholes was negatively correlated to their incline angles bringing the neem s superiority into full play based on the generation of new free surfaces in steps with respect to the time aspect the charging intervals of the inclined boreholes were designed to obtain the best stress compensation and highest fracturing efficiency a field trial was carried out in pingdingshan no 2 mine the results of which showed that some radial cracks were produced around the charging boreholes and that they propagated to the pilot boreholes moreover four main cracks were formed and were approximately parallel to the direction of the borehole rows in a fracturing group a fracture network was eventually generated which verified the expansion capacity of the neem and the feasibility of the spatiotemporal coupling fracturing method for field application

physical modelling of subsidence from sequential extraction of partially overlapping longwall panels and study of substrata movement characteristics field examples of subsidence from sequential extraction of overlapping coal longwall panels have shown that complex and unexpected subsidence effects can occur physical models comprising sand and plaster obeying relevant similarity rules were used to investigate the subsidence mechanisms displacements within the models were measured using a combination of optical transducers photogrammetry and laser scanning the observed results were compared with finite element models the models demonstrate that the incremental subsidence and substrata movement profiles after lower seam extraction can be separated into three different zones these zones undergo different horizontal and vertical movement characteristics the zone of overlap of the two longwall panels undergoes greater total subsidence compared to a single seam of equivalent thickness the limit angle of the subsidence also differs at the two ends of the lower extraction as a result of the effects of the previously mined out area above

getting granite dikes out of the source region whether a dike can propagate far from a magma reservoir depends upon the competition between the rate at which propagation widens the dike and the rate at which freezing constricts the aperture available for magma flow various formulations are developed for a viscous fluid at temperature t sub m intruding a growing crack in an elastic solid the initial solid temperature equals t sub m at the source and decreases linearly with distance from the source if t sub m is the unique freezing temperature of the fluid dike growth is initially self similar and an essentially exact solution is obtained if t sub m is above the solidus temperature the solution is approximate but is designed to overestimate the distance the dike may propagate the ability of a dike to survive thermally depends primarily upon a single parameter that is a measure of the ratio of the dike frozen margin thickness to elastic thickness perhaps more intuitively one may define a minimum distance from the essentially solid reservoir wall to the point at which the host rock temperature drops below the solidus necessary for dikes to propagate far into subsolidus rock it is concluded that for reasonable material properties and source conditions most basalt dikes will have little difficulty leaving the source region but most rhyolite dikes will be halted by freezing soon after the magma encounters rock at temperatures below the magma solidus while these results can explain why granitic dikes are common near granitic plutons but rare elsewhere the potentially large variation in magmatic systems makes it premature to rule out the possibility that most granites are transported through the crust in dikes nonetheless these results highlight difficulties with such proposals and suggest that it may also be premature to rule out the possibility that most granite plutons ascend as more equidimensional bodies

metamorphism and 40ar 39ar dating of the halaban ophiolite and associated units evidence for two stage orogenesis in the eastern arabian shield the arabian shield has long been recognized as a region where plate tectonic processes have been in action during most of the late proterozoic resulting in the amalgamation of the shield s five constituent terranes along four major suture zones studies thus far carried out on these collisional belts have concentrated on the origin and dating of intermediate to acidic igneous rocks and very little emphasis has been placed on the understanding of metamorphic processes operative during plate convergence the al amar suture separates the afif microplate from the ar rayn block in the easternmost section of the shield among several ophiolite occurrences in this suture the halaban belt is by far the largest and preserves within and around it a record of a number of thermal structural events related to the opening and eventual closure of a supra subduction zone back arc basin that existed in the period 695 680 ma the bimodal nature of 40 ar 39 ar dates from the halaban ophiolite and associated units is indicative of a two stage orogenesis climaxing at 680 and 600 ma instead of the previously proposed model of a single orogenic episode between 670 and 630 ma the first stage 680 ma is believed to be related to basin closure and ophiolite emplacement as the ar rayn island arc collided with the afif microcontinent the second episode 600 ma was the outcome of a major collisional event between the arabian craton and a large continental mass east of the ar rayn block

mechanisms of pluton emplacement and structural evolution of a 2 1 ga juvenile continental crust the birimian of southwestern niger abstract the 2 1 ga birimian terranes of southwestern niger consist of a granite greenstone association the structures of the greenstone belts result from the interference between pluton emplacement and regional transcurrent deformation sinistral n s strike slip faults ne sw trending schistosity the regional cleavage trend is observed to change in the vicinity of elliptical plutons cleavage trajectories bend around their contacts resulting in triple junctions at the pluton extremities and narrow aureoles of intense penetrative schistosity and high grade amphibolitefacies metamorphism are developed around them structural features of plutons suggest syntectonic emplacement and age data indicate that all plutons were emplaced between 2 16 and 2 10 ga the plutons are assembled in two distinct types of batholith elongated either parallel or perpendicular to the inferred regional shortening direction a batholith parallel to the inferred regional shortening direction dolbel batholith consists of km sized subcircular alkali granite plutons except for the southernmost one which is of a larger size and exhibits an elliptical shape with a nw se short axis parallel to the shortening direction crosscutting relationships indicate a progressively northward emplacement trend for those plutons internal fabrics generally correspond to layering and magmatic flow fabrics and accessorily to schistosity and shear zones which represent late stage plastic deformation restricted to the pluton margin batholiths which are perpendicular to the inferred regional shortening direction are composed of large elliptical plutons 500 to 5000 km 2 in area consisting mainly of granodiorite and covering 70 of the region the plutons never show crosscutting relationships but are moulded against each other their internal fabric corresponds to a solid state foliation it either dips towards the centre of the pluton funnel or teardrop shaped intrusions or is subhorizontal in the centre and vertical at the margin dome shaped intrusions the foliation and the geometry of the largest pluton tera pluton were acquired during pluton ascent and inflation whereas the geometry of later shear zones indicates that deformation in the pluton was then passively acquired at the final emplacement level due to regional deformation the contrast in both the orientation and structural features of the batholiths reflects distinct emplacement mechanisms the small alkali granite plutons resulted from magma injection within nw se fractures parallel to the inferred regional shortening direction whereas the granodiorite plutons are assumed to be emplaced as diapirs forceful intrusions with long axes perpendicular to the shortening direction these two intrusion mechanisms for plutons emplaced during the same deformation event and at the same crustal level are considered to reflect a local change in the rheological behaviour of the crustal segment studied in connection with the thermal effect induced by the large granodioritic plutons this vertical tectonic regime appears to be typical of palaeoproterozoic juvenile continental crust areas and related to an interplay between emplacement of tremendous volumes of granodioritic magma and a regional transcurrent deformation

determination of actual limit angles to the surface and their comparison with the empirical values in the upper silesian basin czech republic abstract this study deals with the determination of the actual limit angles in the long term formed subsidence basin in the czech part of the upper silesian basin the remaining part lays in poland here there was the most extensive underground exploitation of black coal in the north east of the czech republic a limit angle is absolutely decisive in the determination of deep mining influences in relation to the current and future utilisation of this territory the two csm and paskov mine localities on the edge of the subsidence basin were selected for this study since they could not have been affected by mining in neighbouring mines on the grounds of the long term levelling monitoring of points on the surface which started prior to mining the horizontal distance between the mined out area and the undisturbed ground surface was identified the impact of limit angle on the surface was calculated by means of the horizontal distance and the established mining depth such identified actual limit angles reached the values of 36 at the csm mine and 25 for the paskov mine the calculated values are significantly lower when compared with the currently applied empirical values of 57 for the csm mine and 56 for the paskov mine this means that the extent of the undermining effects is unambiguously wider by 611 m at the csm mine and by 883 m at the paskov mine this study thus establishes the existence of a significantly vaster area influenced by coal deep mining than previously expected the identified facts lead to the conclusion that regular revisions and follow up updates of the empirically determined parameters are recommended

upshot of strata movement during underground mining of a thick coal seam below hilly terrain underpinning based simultaneous extraction was successfully used to extract more than 90 of thick and contiguous sections of a coal seam at chirimiri mine lying below a hill cap with a rapid change in depth of cover and is placed above the surrounding ground level the last few panels of the mine encountered strata control problems during the depillaring underground instrumentation and observations showed that the last phase depillaring of the property near the free surface of the hill slope experienced shearing of overlying strata along two incompetent layers field investigations revealed that large amount of lateral movement due to the hilly nature of the overlying strata is the main source of the problem a simple two dimensional study on a simulated model also demonstrated the occurrence of the problem during working below an unconfined rock mass of hilly nature different evidences were collected from the site to identify the main horizons and the direction of lateral movement and accordingly two different strata management plans one for each section were successfully executed to overcome the encountered strata control problems field investigations in the rest of the panels of the site showed favourable impact of the adopted strata management plan

role of eddies in cooling the leeuwin current 1 the poleward flow of the leeuwin current dominates the surface circulation off western australia along its path it cools by about 5 c over 1350 km based on an eddy permitting simulation using the parallel ocean program model we find that 70 of the heat advected into the coastal region off western australia by the narrow mean jet is transferred to the ocean interior through eddy heat fluxes the eddy fluxes are associated with processes operating at submonthly timescales and despite the current s clear seasonal variability seasonal rectification plays little role in the mean heat balance the 43 tw transferred offshore by eddies is the primary means by which the ocean interior 22 s 34 s and east of 107 e is warmed and the leeuwin current cooled the leeuwin current jet and the eddies allow air sea fluxes to transfer over 40 w m 2 of heat to the atmosphere in the southeast indian ocean

on the factors influencing the development of sporadic upwelling in the leeuwin current system cumulates the highest number of upwelling 140 days per year and is characterized by longer events the intensity of intermittent upwelling is influenced by the upwellingfavorable winds the characteristics of the leeuwin current e g onshore geostrophic flow mesoscale eddies and meanders stratification and nitracline and the local topography this suggests that short living nutrient enrichment of variable magnitude may occur at any time of the year at many locations along the wa coast

bottom boundary layer flow and salt injection from the continental shelf to slope 1 austral winter oceanographic measurements from the northwest australian continental shelf reveal salty water forming evaporatively inshore moving across the wide shelf near the bottom and into the adjacent open ocean when the shelf edge alongshore flow is equatorward the salt tongue is absent during more normal conditions when the poleward leeuwin current is present we hypothesize that the flow reversal enables shelf wide bottom boundary layer ekman transport and thus creates the shelf edge convergence that accounts for the observed salt tongue this flow is absent under sustained normal conditions because of buoyancy arrest in the bottom boundary layer

surficial sediments on the continental shelf of tasmania australia abstract the continental shelf around the island of tasmania and in adjacent bass strait is veneered with quaternary palimpsest sediment composed of quartzose sand relict pleistocene carbonate particles and abundant holocene biogenic carbonate neritic deposits to water depths of 200 m are predominantly coarse grained ranging from gravels to sands to muddy sands the only true carbonate muds lie in the centre of bass strait this pattern reflects the overall high energy sea state and winnowing action of southward flowing currents along the outer shelf sediments can be resolved into three megafacies dominated either by quartzose sand inner shelf and around islands in bass strait relict carbonate particles mid shelf and near islands in bass strait or holocene biogenic carbonate inner to outer shelf facies can be distinguished depending upon whether bryozoans molluscs or other biofragments are dominant relict particles on the mid shelf are only present in large numbers on the western margin and around islands in bass strait they are a minor component of deposits on the eastern shelf this situation is interpreted to reflect higher overall carbonate production on the eastern shelf promoted by increased trophic resources via upwelling of subantarctic waters holocene molluscs especially infaunal bivalves are most prominent on the inner shelf holocene bryozoans are the most numerous particles overall and most abundant on the western shelf reflecting preferential conditions for growth probably promoted by episodic mid shelf upwelling bryozoan fragments can be separated into associations dominated by either 1 shallow water erect flexible articulated branching or articulated zooidal growth forms or 2 mid to outer shelf erect rigid fenestrate or flat robust branching types less abundant vagrant growth forms are limited to shallow waters whereas delicate branching forms are localized to deep waters nodular arborescent growth forms mainly celleporaria sp occur in both shallow and deep waters but are unusual on most of the shelf superimposed on this depth related distribution is a north to south cool to cold trend the whole spectrum of bryozoans is present on the shelf in the north whereas in the south bryozoan biofragments are mostly erect flexible with delicate branching forms restricted to the outer shelf and upper slope the change coincides with the furthest northward extent the subtropical convergence zone during winter surficial sediments in bass strait are most comparable to those on the extensive continental shelf to the west off southern continental australia where inboard sediment production takes place in environments populated by macroalgae but dominated by seagrasses where water depth is

wind forced downwelling slope currents a numerical study abstract a study is made of the dynamics of slope currents that arise from a steady constant alongshore wind over a uniform shelf over the first 10 20 days the evolution of the downwelled system on an f plane is qualitatively described by linear coastal trapped wave dynamics after this time the thermal wind shear associated with the bottom mixed layer becomes important in the evolution of the undercurrent uc which is shown to be driven by the alongshore pressure gradient due to sea level as the uc over the slope evolves the bottom ekman transport becomes small and negative leading to the detachment of flow near the shelf break localized spreading of isopycnals and further intensification of the uc in contrast to results obtained without bottom drag bottom friction and boundary layer transport are shown to lead to a two to threefold increase in cross shelf interior transport downwelling and thermal wind shear by day 60 the resultant uc has speeds of up to 15 cm s 1 and a net transport of

theory and validation of the multiple window sea surface temperature technique the development of the split window approach for correcting satellite measurement of radiance for atmospheric attenuation is reviewed then the theoretical results are compared to results from actual measurements which consist of satellite measurements in the three infrared windows of the avhrr ground truth for the comparisons comes from buoys the satellite measurements were screened for clouds and the remaining ones were used in the analysis using this data set several statistical analyses were performed these showed that when the two channels that are truly a split window are used the result of the statistical model agrees with the one derived from theoretical considerations when the 3 8 m channel is combined with one in the 10 12 m region the result of the statistical model does not take the split window form results show that the method is capable of producing sea surface temperatures with a standard deviation of 1 k or less

sea level variability due to meteorological forcing in the northeast gulf of st lawrence in an attempt to understand the causes of low frequency flow through the strait of belle isle we relate sea level data from four stations in the northeast gulf of st lawrence to meteorological forcing our main tool is a multiple regression at each frequency of sea level on local atmospheric pressure and two orthogonal large scale pressure gradients which represent geostrophic winds the results show an inverted barometer response to atmospheric pressure and a frequency dependent response to wind which can be tentatively interpreted in terms of coastal setup due to wind driven longshore currents or barotropic setup of semi enclosed regions such as the northeast gulf or the whole gulf a simple model for barotropic flow through the strait is developed in order to provide an estimate from data at the western end of the strait of sea level changes on the labrador shelf

magmatic belts in accretionary margins a key for tectonic evolution the tonalite belt of north victoria land east antarctica occurring in the early palaeozoic palaeomargin of the east antarctica craton the tonalite belt of north victoria land is a narrow linear magmatic belt up to 200 km long made up of strongly foliated tonalitic and granodioritic intrusions they were synkinematically emplaced into the lanterman murchison shear zone a major tectonic structure across which different tectono metamorphic terranes were accreted during the late cambrian ross orogeny the deformational and kinematic features of the intrusions indicate that strain and displacement during terrane accretion were partitioned into oblique thrust high angle thrust and strike slip shear zones from this it is deduced that a transpressional regime prevailed during early palaeozoic deformation and terrane accretion this and other magmatic belts which exploited major tectonic structures in collisional margins such as the coast plutonic complex of nw america are basic keys for understanding deformational processes and kinematic regimes during terrane accretion moreover the occurrence of such types of magmatic belts might be regarded as a reliable indication of large scale strike slip motion between accreting terranes in an oblique convergent setting

simulation of chlorophyll and iron supplies in the sub antarctic zone south of australia the sub antarctic zone saz is part of the high nutrient low chlorophyll region of the southern ocean where low iron availability limits phytoplankton productivity in the tasman sea the saz displays a unique and large zonal gradient in the surface chlorophyll concentrations in situ measurements show higher dissolved iron in the east than in the west which could explain the zonal chlorophyll gradient to assess and quantify the major sources of iron in this region we use an eddy resolving model to simulate the dissolved fe distribution arising from both the shelf and the dust supply of iron the simulation showed that dissolved fe from the shelf is only transported eastward to about 155 e and the shelf source of dissolved iron is unable to supply iron to the entire tasman sea saz region even when we assume that there no iron losses the simulation with the atmospheric source of iron showed that through a combination of atmospheric transport and ocean transport enough dissolved fe can be supplied to the entire tasman sea saz region to relieve iron limitation from the model simulations we conclude that atmospheric iron supply is essential to generating the observed gradient of the chlorophyll in the saz region of the tasman sea

surface stepped subsidence related to top coal caving longwall mining of extremely thick coal seam under shallow cover the surface stepped subsidence had badly affected the public infrastructure safety the formation mechanism of the surface stepped subsidence case was explained the surface subsidence profile after the sequent mining activity was predicted the possible controls of the stepped subsidence were lastly proposed

aspects of the mean wintertime circulation along australia s southern shelves numerical studies abstract a high resolution numerical model is used to study the mean wintertime shelf slope circulation between the gulfs of south australia and the west coast of tasmania the mean downwelling favorable winds for the region result in a continuous eastward coastal current cc extending from cape leeuwin to the eastern coast of tasmania the magnitude of the cc is generally largest over the shelf break has speeds of more than 40 cm s 1 transport 2 4 sv sv 106 m3 s 1 and is generally in good agreement with observations the relative importance of the leeuwin current zonal winds and density gradients to the shelf circulation is established within bass strait the eastward circulation is in good agreement with observations and simple models show that about 30 of the transport arises from local winds and the remainder from the cc the total transport through the strait 0 95 sv is shown to be controlled by sea level on the east coast of tasmania a current of up to 10 cm s 1 is also found to flow

melt segregation in migmatites anatectic stromatic migmatites have a symmetrical layered structure with a low ratio of thickness to length and a periodicity features that have not been explained satisfactorily but which are related to physical processes of melt segregation we evaluate the compaction model for segregation as it applies to migmatites and develop models for melt segregation based upon convection driven by volume change and upon advection down pressure gradients that result from applied differential stress acting on an anisotropic multilayer protolith compaction by gravity driven two phase flow results in asymmetric separation yields calculated segregation times that are slow or geologically unreasonable and yields relative volumes that are not consistent with the abundance of leucosome seen in natural migmatites although calculated segregation times for very wet granite might allow segregation by compaction some driving force in addition to gravity is needed to cause widespread melt segregation in the crust for segregation at low volume fraction of melt we develop a two dimensional two phase matrix and fluid viscous flow cell model length much greater than thickness with phase changes which predicts either expansion or contraction convection depending on whether volume change vr is positive or negative convection leads to melt segregation to form a stromatic structure in a geologically reasonable timescale at moderate volume fraction of melt segregation may occur by filter pressing in compositionally layered rocks in response to applied differential stress melt migration is by porous medium flow driven by differences in mean normal stress between the layers as a consequence of differences in rheology and shear enhanced matrix collapse calculated segregation rates are fast and the model yields adequate volume of leucosome the positive vr for volatile phase absent melting reactions under crustal pressures promotes melt escape unless extensional deformation facilitates melt accumulation if the rate of melt production exceeds the rate of melt escape then the increase in melt pressure may lead to melt enhanced embrittlement and fracture and melt may migrate out of the system in contrast water rich volatile phase present melt producing reactions have a negative vr which promotes melt retention after segregation unless deformation generates melt escape pathways evolution of stromatic structure through anatectic erosion of mesosome by increasing the melt fraction in situ may lead to breakdown of the solid matrix and will lead to instability due to buoyancy and magma may become mobile and entrain residual material restite

assessment of rock mass characteristics and the excavation disturbed zone in the lingxin coal mine beneath the xitian river china safe production and induced hazard prevention in coal mines mainly concern problems in the excavation disturbed zone edz but coal mining can also make a significant impact on the environment comprehensive techniques using a borehole tv viewer system electrical logging and monitoring of drilling fluid leakage offer the ability to identify changing geological conditions and the location of any nearby abandoned mining workings the inner collapsed zone and the expanding height of the crack zone transmitting water plus their spatial distribution after excavating the superincumbent coal seam stratum are determined at no l3414 workings lingxin coal mine beneath the xitian river china an integrated system of gis based on a stochastic model which has been developed for the prediction of dynamic subsidence coupling the time function and probabilistic integral method is verified through practice at the lingxin coal mine this development has greatly expanded the ability of the mine operator to characterize previously inaccessible areas of the mine providing a reliable basis for safe mining and prevention of induced hazards to ensure high production mining underneath the river bed

temperate shelf water dispersal by australian boundary currents implications for population connectivity boundary currents have been recognized as potential drivers of spatial heterogeneity in the ocean because of their role in physical transport and influence on large scale coastal processes in this study we used particle tracking methods in a data assimilating eddy resolving ocean circulation model to determine the effect of multiple boundary currents on connectivity around temperate australia during the austral winter results demonstrated that oceanographic connectivity was asymmetric around australia having greater eastward trajectories due to more favorable ocean boundary currents during this season we validated connectivity patterns with genetic data from an ecologically important species the kelp ecklonia radiata which has greater genetic similarity between the west and south coasts of australia compared with the east coast likely due to predominantly eastward propagule dispersal boundary current circulation was a coarse predictor of kelp genetic connectivity on multigeneration time scales and the nature of these relationships varied among the three boundary current systems according to mean current strength

a system to mitigate deep mine tremor effects in the design of civil infrastructure deep mining may induce quakes reaching magnitude ml of 4 5 to 5 5 and leading to surface ground motion with modified mercalli intensities up to viii such strong ground motions may cause serious damages in civil infrastructure in the vicinity of mines however any adaptation of a classic seismic code in design faces an impending problem of differences in spectral content and duration between the surface records of the rockbursts and natural earthquakes as well as in their different risk definitions this paper presents a system to define design seismic load based on forecasted surface horizontal particle velocity from the rockbursts expected during the planned mining activities such forecasts are routinely prepared by the geophysical mine services respective seismic load may then be applied in the design of buildings and other structures to mitigate the rockburst induced seismic effects on them for this purpose the european seismic code eurocode 8 is adapted

igneous emplacement in a transpressive shear zone ox mountains igneous complex the central and southwestern ox mountains inlier in western ireland comprises amphibolite facies metasediments and metavolcanic rocks which have been deformed by a major sinistral shear zone granitoid emplacement occurred in two distinct styles in the ox mountains shear zone the older pluton the ox mountains granodiorite was emplaced syn kinematically with respect to the main sinistral transpressional events in its wall rocks it was emplaced as a series of compositionally distinct sheets in the central part of the shear zone system thus suggesting the formation of transient dilational sites occurred in response to the transpressive deformation the younger lough talt and easky lough adamellites were emplaced as individual intrusions in dilational cavities produced by reactivated movements on a discrete zone within the ox mountains inlier the different intrusive styles are considered to be a product of the tectonic regimes operating during emplacement intrusion into transient dilational cavities may be one method by which granitoid magmas are emplaced into fault zones undergoing active contractional deformation

estimation of limit angle using laminated displacement discontinuity analysis in the soma coal field western turkey determination of the limit angle at the manisa soma eynez coal field a major coal production area in turkey is difficult because of the presence of a landslide caused by the waste from a neighboring open pit site being dumped over the underground mine at the soma eynez basin in fact it is not possible to determine the effect of extraction on the surface from field studies thus in order to determine the limit angle in situ subsidence measurements geophysical measurements rock based tests in the laboratory and the data obtained from a physical model have supported numerical modeling studies the software lamodel used for the numerical modeling was developed by national institute for occupational safety and health niosh and is based on the boundary element method the results obtained from modeling have been found to be compatible with other studies and as a result the limit angle has been determined

linking synoptic forcing and local mesoscale processes with biological dynamics off ningaloo reef 1 a hydrographic survey offshore ningaloo reef north west australia in austral autumn 2010 revealed relatively stable subsurface water masses in the region despite the influence of interannual variability of the leeuwin current lc the surface water mass seems slightly more variable at seasonal time scale probably due to various contributions of the geographically distinct source waters of the lc a subsurface nitrate maximum 110 230 m a prominent feature of the ningaloo area during autumn was consistently observed within different water masses tightly coupled variations of subsurface nitrate and oxygen at small vertical scale suggest it is due to local in situ remineralization of organic matter likely to accumulate along sharp physical interfaces and possibly favored by injections of oxygenated subsurface waters offshore enhanced levels of surface chlorophyll a within the downwelling favorable lc are associated with deeper mixed layer depth eroding the shallow source of nutrients close to the continental shelf these nutrients are observed to be efficiently uplifted within the core of quasi persistent topographically trapped submesoscale cyclonic eddies dominated by nonlinear effects a wind driven coastal upwelling event occurred in autumn and was characterized by a relatively deep source 100 150 m coinciding with the subsurface maximum of nutrients thus promoting coastal productivity locally and farther north by alongshore advection within the ningaloo current

ground subsidence observations and a modified influence function method for complete subsidence prediction abstract the results of surface subsidence investigations carried out in different coal fields in india are presented in this paper important differences are seen to exist between the subsidence norms given in the subsidence engineers handbook uk and those obtained in indian conditions differences also exist for extraction below unfractured or uncaved rock and below pre existing caved goaf s the subsidence is higher in the latter case and also in the slopes and strains consequently separate equations and guidelines have been given for these two conditions of mining since indian coal mining is mostly under shallow to moderate cover several cases of discontinuous subsidence have been observed a demarcation limit for discontinuous subsidence is given seeing that discontinuous subsidence causes severe surface damage since room and pillar mining is the principal underground method of extraction panels of irregular shapes often occur making complete subsidence prediction difficult the influence function method with a new function and additional functions for modelling subsidence asymmetry and the effect of extraction edges are given in this paper the method for extraction below goaf s is also examined four cases are given for the comparison of observed and predicted subsidence contours and two cases for comparison of the slopes and strains

predicting of land surface uplift caused by the flooding of underground coal mines a case study abstract the liquidation of underground mines as in flooding of mining excavations and goafs often leads to movements of the rock mass and land surface as a result of pressure changes in the flooded zones the changes resulting from the rising water table caused by the changes in the stress and strain state as well as the physical and mechanical properties of rock layers can lead to damage to surface construction objects and environmental changes such as chemical pollution of the surface water this is why the ability to predict the movements of rock masses generated as a result of mine closure by flooding serves a key function in relation to the protection of the land surface and buildings present thereon currently the world literature presenting methods of forecasting ground surface uplift during mine flooding is very modest and is limited to three analytical methods pottgens fenk s and sroka s method however the numerical methods used in this subject area are limited only to modeling the phenomenon using the back analysis method and are not used for forecasting the author s methodology based on the finite element method presented in the article allows on after calibrating the 3d numerical model using surface subsidence measurements as well as geological and mining data to simulate the flooding process by changing the density of the medium according to classical soil and rock mechanics principles and then obtain prognostic values for ground surface uplift this methodology has been used in the example of a german underground coal mine which has been flooded in 1999 the authors have built a 3d numerical model and then performed simulations the results of calculations were compared with the results of measurements obtaining compliance at the level of 5

emplacement of the nain anorthosite diapiric versus conduit ascent estimation of settling velocities of large orthopyroxene megacrysts found within anorthosite intrusions are calculated and compared with ascent rates achieved by diapirism and conduit propagation calculations suggest that diapirism is far too slow to be an appropriate ascent mechanism for anorthositic crystal mush and favour conduit emplacement the intrusions of the nain plutonic suite nps are located along the abloviak shear zone which marks the boundary between the nain and churchill provinces and within the zone of juxtaposition of the saglek and hopedale blocks of the nain province these crustal weaknesses have probably controlled the emplacement and distribution of the intrusions contact relations between intrusions of anorthosite and their gneissic host rock provide evidence for two emplacement styles within the nps the first typified by strongly deformed and recrystallized rocks and the second by an outer border zone of mafic rocks it is proposed that these differences in intrusive style are due to differences in ductility contrast between the magma and its surrounding host rocks such that those intrusions emplaced into the thermally softened shear zone have deformed margins whereas those intruded into the cooler archaean crust have undeformed margins

simple method for the identification of subsidence susceptibility above underground coal mines in korea estimation of subsidence susceptibility due to mining is a primary task for the effective and economical management of subsidence if the status of an underground mine is well known this process is simple and clear unfortunately in korea the excavation shape is typically complicated because of the complex geological characteristics and corresponding mining methods and relevant data on abandoned or closed coal mines are often deficient therefore estimation methods developed elsewhere are usually not suited to korean coal mines to solve this problem we developed a quick simple and quantitative method suitable for the estimation of subsidence susceptibility prior to the detailed field investigation of coal mines gangway depth from the surface and the attitude dip and dip direction of main geological features were selected as input data based on the degree of availability and reliability and the gangway was represented as a series of points instead of closed polygons for easy calculation two core assumptions of this method were that the susceptibility to subsidence within a unit area increases as i the depth of the gangway from the surface decreases and ii the number of gangways below the unit area increases in spite of the simplicity of this method it gave satisfactory results when applied to one virtual excavation model and two closed coal mines where subsidences had occurred

formation morphology and preservation of high energy carbonate lithofacies evolution of the cool water recherche archipelago inner shelf south western australia cool water carbonate environments are responsible for up to one third of the carbonate sediment produced on continental shelves and are useful modern analogues for many geologically ancient carbonate deposits on modern and ancient high wave energy carbonate ramps it has been suggested that wave abrasion generally limits sediment accumulation to the outer shelf sediment are produced on the modern inner shelf although few studies have investigated processes of sedimentation in these energetic environments the recherche archipelago in the west of the great australian bight gab was examined to better identify processes of carbonate sedimentation and preservation on extremely high energy shelves surficial sediments video traverses multibeam sonar data cores and shallow seismics were analysed these data reveal that the topographically varied environment of the recherche archipelago experienced gradual episodic accumulation of a prograding sediment wedge with substantially thicker deposits located on the lee side of topographic highs modern sediment accumulation is largely restricted to the shoreface and inner shelf where the highly discontinuous storm influenced blanket of holocene sediment comprises a shore attached quartzose sediment prism leeward accretionary wedges and rhodolith beds above a laterally continuous pecten dominated basal transgressive lag storm events play an important role in these environments resulting in a mostly bare shaved middle and outer shelf onshore sediment transport reworking of particles and periodic removal of sediment the modern recherche archipelago is a high energy end member of cool water carbonate environments in which calcareous algae dominate sediment production modern esperance bay provides a useful analogue for the interpretation of high energy palaeoenvironments and demonstrates that in addition to sea level change wave energy and local geomorphology are important considerations for carbonate facies reconstructions this study has presented new information for carbonate inner shelves that differs from classic carbonate ramp models showing that ancient rhodolith bearing carbonate deposits have the potential to form and be preserved in very high energy settings

the effect of the metal deposits exploitation on the safe operation of water conservancy project ground subsidence which is caused by metal mining is generally forecast using research results and experiences of coal mining for reference at present this paper considers that predictive study on the ground subsidence which is induced by metal mining must use suitable calculation methods under some specific circumstances a comprehensive research method combining numerical simulation and engineering analogy is the most reasonable approach to predict ground subsidence induced by mining the author takes practical engineering as example firstly a three dimensional geological model was established on the basis of surveying and mapping for the study area in large scale using the three dimensional laser scanner secondly the rock fragment strength was tested with the schmidt hammer and the rock point load strength instrument at the same time a detailed statistical analysis of joints and fractures of underground rock were made and strength indexes of surrounding rock were determined on the basis of rock mass classification according to the rock mass rating rmr classification system finally the surface movement induced by mining and the seepage field of the boziliang sub dam were simulated using fast lagrangian analysis of continua in three dimensions flac 3d and visual modflow respectively the results of simulation indicate that it would not affect the safe operation of the boziliang sub dam as long as the exploitation in the madaozi iron mine conformed with the design requirements and was accompanied by monitoring work and the worked out areas being filled in time

modeling studies of the leeuwin current off western and southern australia the leeuwin current strengthens considerably from february to may each year following the slackening of southerly coastal winds strong eddies develop a high resolution multilevel primitive equation ocean model is used to examine this eddy development in an idealized way by considering the development of flow from rest when temperatures are initially given the observed longshore gradients the system is allowed to geostrophically adjust in the absence of longshore winds and of any surface heat flux two types of experiments are conducted the first type uses the indian ocean climatological temperature gradient forcing case 1 and 2 while the second type repeats the first experiment with the added contribution of the north west shelf nws temperature profile cases 3 and 4 to investigate the additional effects of coastline irregularities cases 1 and 3 use an ideal coastline while cases 2 and 4 use an irregular realistic coastline in all cases maximum surface velocities occur at cape leeuwin where the leeuwin current changes direction and off southern australia maximum undercurrent velocities occur off western australia in case 1 cape leeuwin and the western australian coast are the preferred locations for the development of warm anticyclonic eddies which are generated due to a mixed instability mechanism in case 2 the warm anticyclonic eddies occur in the vicinity of coastal promontories and at cape leeuwin while advection of warm water is present along the entire coast in case 1 the irregular coastline geometry limits the extent of warm water in case 2 the added contribution from the nws water in cases 3 and 4 augments the onshore geostrophic inflow to produce a model leeuwin current and undercurrent that are more vigorous and unstable than in the previous cases in case 3 the nws water adds strong horizontal shear to the coastal equatorial region of the domain and vertical shear to the inshore current it also advects warmer water along the entire coast in case 4 the addition of both the nws water and the irregular coastline results in the establishment of a stronger surface current and undercurrent than in the previous cases however the irregular coastline limits the extent of the advection of the nws warmer water along the australian coast in all cases warm anticyclonic eddies develop at the coast cold cyclonic eddies form from the limbs of the established warm anticyclonic eddies with the result that two counterrotating cells are developed once the eddy pairs begin their westward propagation the leeuwin current intensifies as nonlinear effects result in a jet between the eddies and the coast these effects translate downstream to augment the current velocities at the coast which due to a mixed instability mechanism result in the development of new anticyclonic eddies at the coast the results from case 4 which has the most realistic features highlights the major characteristics of the leeuwin current and agrees well with available observations these results show that the model successfully captures the qualitative nature of the nonlinear eddying response of the leeuwin current

analysis of the evolution of ground movements in a low densely urban area by means of dinsar technique abstract this paper presents an application example of the use of the differential interferometry synthetic aperture radar technique dinsar for monitoring ground movements in a geologically complex area around the village of suria ebro basin catalonia ne spain associated to underground mining activities and to the presence of a salt dome the analysis has been mostly performed in a rural environment affected by ground movements with different patterns magnitudes and causes a total of fifty sar images recorded between 1995 and 2007 were processed to generate the interferograms in order to study the non linear trends or changes of the ground surface behavior the dinsar technique was applied in two sets of images the interferometric results in the form of vertical displacement rate maps were checked against conventional surveying and gps measurements the results present a significant discrepancy in some location due to the wrapping of the phase when both fast and significant deformations occur in order to avoid the latter effect and improve the accuracy of the results all sar images were reprocessed using topographic leveling and gps data of different monitored points to support the dinsar interpretation a detailed geological reconnaissance of the study area was carried out as well as an inventory of ground movement indicators four different patterns of ground movement have been identified active shifting subsidence associated to the progression of the mining exploitation fronts residual subsidence on abandoned galleries with a decreasing rate of closure uplifting due to the intrusion of the salt dome and sudden ground collapses sinkholes caused by the dissolution of soluble materials laying close to the ground surface

a review of the shelf slope circulation along australia s southern shelves cape leeuwin to portland abstract a review is presented of the ocean circulation along australia s southern shelves and slope uniquely the long zonal shelf is subject to an equatorward sverdrup transport that gives rise to the flinders current a small sister to the world s major western boundary currents the flinders current is strongest near the 600 m isobath where the current speeds can reach 20 cm s and the bottom boundary layer is upwelling favourable it is larger in the west but likely intermittent in both space and time due to possibly opposing winds thermohaline circulation and mesoscale eddies the flinders current may be important to deep upwelling within the ubiquitous canyons of the region during winter the leeuwin current and local winds act to drive eastward currents that average up to 20 30 cm s the currents associated with the intense coastal trapped wave field 6 12 day band are of order 25 30 cm s and can peak at 80 90 cm s wintertime winds and cooling also lead to downwelling to depths of 200 m or more and the formation of dense coastal water within the great australian bight and the south australian sea within the great australian bight the thermohaline circulation associated with this dense water is unknown but may enhance the eastward shelf edge south australian current the dense salty water formed within spencer gulf is known to cascade as a gravity current to depths of 200 m off kangaroo island this dense water outflow and meanders in the shelf circulation also fix the locations of a sequence of quasi permanent mesoscale eddies between the eyre peninsula and portland during summer the average coastal winds reverse and surface heating leads to the formation of warm water in the western great australian bight and the south australian sea no significant exchange of shelf water and gulf water appears to occur due to the presence of a dense nutrient rich sub surface pool that is upwelled off kangaroo island the winds lead to weak average coastal currents increasing evidence suggests that el nino events 4 7 year period can have a major impact on the winter and summer circulation these events propagate from the pacific ocean and around the shelf slope wave guide of west australia and into the great australian bight during winter el nino events the average shelf currents may be largely shut down during summer the thermocline may be raised by up to 150 m the nature and role of tides and surface waves is also discussed along with uncertainties in the general circulation and future research

estimating horizontal and vertical movements due to underground mining using alos palsar abstract in this paper the capability of determining the three dimensional 3d ground displacements due to underground mining using the multiple alos palsar interferometric pairs acquired with different viewing geometries has been investigated and validated in the area of west cliff colliery new south wales nsw australia four alos palsar interferometric pairs acquired with two different incidence angles from both ascending and descending orbits were used in this study three different approaches were used to derive the 3d displacement maps the first two approaches utilised sar data only while the third approach required a one dimensional measurement by using other surveying techniques as inputs the results were compared with the gps field survey data obtained between april and may 2008 the obtained results and the gps data agreed well with each other in the vertical and the east west directions however the precision of displacement measured in the north south direction was much poorer for the first two approaches compared to the third approach this was due to two reasons 1 the lack of viewing geometries and 2 the poor temporal overlap in the interferometric combination datasets the results suggested that it is possible to use other one dimensional surveying techniques to assist the insar measurements in order to enhance the accuracy of the 3d deformation derived the horizontal movements in transverse and longitudinal directions were calculated from the 3d deformation results in order to derive the subsidence parameters that have been caused by mining activities the subsidence parameters derived matched well with the gps derived parameters the results suggested that an accurate 3d displacement vectors can be derived by combining insar measurement with measurement from other equipment such as extensometer and optical fibre which may carry out measurement in one direction only ideally north south direction

seasonal circulation around tasmania an interface between eastern and western boundary dynamics 1 the seasonal circulation connecting the pacific and indian oceans around tasmania is documented using seasonal maps from satellite altimetry and sea surface temperature sst and in situ mean fields from a high resolution climatology of the region commonwealth scientific and industrial research organisation csiro atlas of regional seas cars in general the surface variability displays a very different character off the east and west coasts off the east coast the variability is generated externally being dominated by the western boundary dynamics of the east australian current eac in the west it is weaker and arises from the seasonal rise and fall of the coastal sea level which is due to the seasonal reversing wind patterns a high variability tongue associated with the eac stretches poleward off the east coast tracing out a waveguide between the major topographic structures it has a broad peak in power between 180 and 365 days 0 08 m which is a surface height expression of the energetic mesoscale eddy activity associated with the eac distinctive summer and winter patterns of the surface circulation are described which are influenced by the eac and the zeehan current zc respectively on the east coast in summer january march there is a poleward advection of warm saline water forced by an episodic coastal boundary flow the cross shelf pressure gradient driving this flow is formed from the difference between the seasonal changes in coastal sea level and the offshore eddies there is a seasonal reversal of this flow in winter with cool fresh modified subantarctic surface waters drawn up from the south off the west coast the zeehan current operates 180 out of phase with the eac it is strongest in winter when it projects warm relatively saline waters down the western tasmania coast and around the southern tip of tasmania there is a sharp division between the eac and zc influence adjacent to the tasman peninsula off southeast tasmania

comparison of organic uk 37 texh86 ldi and faunal proxies foraminiferal assemblages for reconstruction of late quaternary sea surface temperature variability from offshore southeastern australia several proxies have been developed to reconstruct past sea surface temperature sst but different proxies may reflect temperatures of different seasons and each proxy is characterized by certain uncertainties therefore a multiproxy approach is preferred to precisely reconstruct sst here we reconstruct sst of the ocean offshore southeastern australia murray canyons area for the last 135 ka using three independent organic proxies texh86 based on glycerol dialkyl glycerol tetraethers gdgts uk 37 based on alkenones and ldi based on long chain diols in addition to foraminiferal faunal assemblages the organic proxy records show similar trends with the highest temperature 21 c for uk 37 and texh86 and 25 c for ldi during the last interglacial and lowest temperature 8 c for texh86 10 c for uk 37 and 12 c for ldi during the last glacial maximum however the differences in absolute sst estimates obtained by the organic proxies varied over time with differences of up to 9 c between ldi and texh86 the seasonal sst reconstructions based on the modern analogue of foraminiferal assemblages also show similar trends as the organic proxies with highest temperatures during the last interglacial 23 c for the warmest month sst 20 c for mean annual and 18 c for the coolest month and lowest temperature during the last glacial maximum 14 c for the warmest month 11 c for mean annual and 9 c for the coolest month down core comparison between the reconstructed ssts of the organic and inorganic proxies shows that ldi inferred temperatures compare well with the temperature of the warmest month texh86 with the temperature of the coolest month and uk 37 with mean annual temperature an increase in texh86 sst estimates relative to those of other proxies during deglaciations and interglacials suggests that either winter temperatures rapidly warmed possibly due to an invigoration of the leeuwin current over the core site or there was a change in the growth season of the thaumarchaeota the source organism of gdgts our study shows the benefits of a multiproxy approach in the interpretation of sst proxies leading to a more robust knowledge of past ocean temperature changes

the tectono metamorphic evolution of the very low grade hangingwall constrains two stage gneiss dome formation in the montagne noire southern france the montagne noire in the southernmost french massif central is made of an ene elongated gneiss dome flanked by palaeozoic sedimentary rocks the tectonic evolution of the gneiss dome has generated controversy for more than half a century as a result a multitude of models have been proposed that invoke various tectonic regimes and exhumation mechanisms most of these models are based on data from the gneiss dome itself here new constraints on the dome evolution are provided based on a combination of very low grade petrology k ar geochronology field mapping and structural analysis of the palaeozoic western mont peyroux and faugeres units which constitute part of the southern hangingwall of the dome it is shown that southward directed variscan nappe thrusting d1 and a related medium p metamorphism m1 are only preserved in the area furthest away from the gneiss dome the regionally dominant pervasive tectono metamorphic event d2 m2 largely transposes d1 structures comprises a higher metamorphic thermal gradient than m1 transition low p and medium p metamorphic facies series and affected the rocks between c 309 and 300 ma post dating d1 m1 by more than 20 ma d2 related fabrics are refolded by d3 which in its turn is followed by dextral normal shearing along the basal shear zone of both units at c 297 ma in the western mont peyroux and faugeres units d2 m2 is largely synchronous with shearing along the southern dome margin between c 311 and 303 ma facilitating the emplacement of the gneiss dome into the upper crust d2 m2 also overlaps in time with granitic magmatism and migmatization in the zone axiale between c 314 and 306 ma and a related low p high t metamorphism at c 308 ma the shearing that accompanied the exhumation of the dome therefore was synchronous with a peak in temperature expressed by migmatization and intrusion of melts within the dome and also with the peak of metamorphism in the hangingwall both the intensity of d2 fabrics and the m2 metamorphic grade within the hangingwall decrease away from the gneiss dome with grades ranging from the anchizone epizone boundary to the diagenetic zone the related zonation of the pre d3 metamorphic field gradients paralleled the dome these observations indicate that d2 m2 is controlled by the exhumation of the zone axiale and suggest a coherent kinematic between the different crustal levels at some time during d2 m2 based on integration of these findings with regional geological constraints a two stage exhumation of the gneiss dome is proposed during a first stage between c 316 and 300 ma dome emplacement into the upper crust was controlled by dextral shear zones arranged in a pull apart like geometry the second stage from 300 ma onwards was characterized by northeast to northward extension with exhumation accommodated by north dipping detachments and hangingwall basin formation along the northeastern dome margin

sediment waves with a biogenic twist in pleistocene cool water carbonates great australian bight abstract sediment waves composed of fine grained carbonate ooze with in place bryozoans are a characteristic element of the pleistocene of the great australian bight gab the low amplitude and strongly elongate sediment waves are up to 10 km long 1 km wide 40 m high and oriented sub parallel to contours immediately off the shelf slope break they are asymmetrical showing up slope migration and mainly occur in trains the sediment waves were drilled during odp leg 182 in 1998 and were interpreted as biogenic reef mounds new high quality seismic and multibeam bathymetry data were acquired on the galathea 3 expedition in 2006 allowing description of the morphology and internal architecture of the sediment waves in unprecedented detail leading to an alternative interpretation of their formation most sediment waves were initiated by preferential deposition on the landward side of irregular erosion surfaces sediment wave accretion took place under the influence of density driven currents which decelerated up the landward dipping flanks and accelerated down the seaward dipping flanks of the sediment waves the currents are interpreted as dense water cascades formed by summer evaporation and strong winter cooling by analogy with oceanographic processes in the present day gab the lithological composition varied with climate and sea level but sediment wave formation did not sediment waves formed and accreted during both glacials and interglacials in contrast to the previous interpretations which involved growth in glacial periods only bryozoans influenced the depositional environment by adding sediment trapping fine grained particles and stabilizing the muddy sea floor this caused the sediment waves to gain a more prominent sea floor relief than most muddy siliciclastic sediment waves formed by similar depositional processes the interpretation of the sediment waves as purely biogenic build ups is rejected and the sediment waves are most appropriately described as biogenically influenced sediment waves

isotopic composition of a large photosymbiotic foraminifer evidence for hypersaline environments across the great australian bight during the late pleistocene abstract analysis of carbon and oxygen isotopic compositions of large benthic foraminifera tests marginopora vertebralis that lived in the great australian bight during the late pleistocene reveal that the tests are enriched by 1 to 3 in both 18o and 13c relative to modern specimens from the same region the intolerance of m vertebralis for cool waters negates lower ocean water temperature as an explanation for such high 18o values the oxygen isotopic compositions are thus interpreted to reflect tests secreted in hypersaline waters of up to 56 ppt salinity concentrated from seawater by evaporation m vertebralis thrives today in waters of similar salinity at shark bay western australia the pleistocene sedimentary assemblage supports an interpretation that environments broadly similar to those in outer modern day shark bay were wide spread across the great australian bight during portions of marine isotope stages 2 3 and 4 the high 13c values of the pleistocene m vertebralis are interpreted to reflect enhanced photosynthetic activity that depletes dissolved carbonate in 12c in such shallow saline settings these hypersaline environments formed during periods of lower sea level when shallow waters