late proterozoic lavas of the central arabian shield evolution of an ancient volcanic arc system a petrological assessment of 11 volcano sedimentary belts in the central arabian shield cas using 118 new analyses is presented the same samples have been used in a rb sr dating programme also reported in this volume the oldest volcano sedimentary belts sequence c 900 ma are chemically immature bimodal suites of low k tholeiites and sodic dacite rhyolite depleted in lithophile elements these lavas have chemical characteristics similar to immature island arcs such as the tonga kermadee and lesser antilles arcs younger lavas of sequence b 900 700 ma are slightly more mature in composition being predominantly calc alkaline and low k arc tholeiite series with higher lithophile element contents they are comparable with pacific island are averages the youngest voluminous lavas sequence a 700 570 ma are generally calc alkaline or high k calc alkaline series lavas with moderately high lithophile element abundances they are comparable to volcanic arcs such as central america and indonesia which are transitional between island arcs and continental margin volcanic arcs the cratonization process in the cas thus involved the superimposition of three volcano sedimentary sequences formed in progressively maturing volcanic arcs early formed immature island arcs were succeeded by chemically more mature island arc deposits and then by deposits formed in volcanic arc s transitional between island arcs and continental margins the evolution ceased at this stage and probably did not advance to the equivalent of an andean continental margin

chronology of late wisconsinan glaciation in middle north america abstract we propose a chronology of late wisconsinan glacial fluctuations in middle north america from alberta to wisconsin based on radiocarbon dates derived solely from wood previous chronologies of the southwestern margin of the north american continental ice sheet have depended to a considerable degree on radiocarbon dates from fine grained organic sediment this material is commonly contaminated with older carbon resulting in chronologic confusion by using only dates from wood much of the confusion disappears however because of the scarcity of wood dates only four of the sixteen identified fluctuations are accurately dated an advance into iowa about 14 000 to 13 500 bp an advance into south dakota and iowa about 12 300 bp an advance into the lake michigan basin about 11 700 bp and an advance into the lake superior basin about 9900 bp in addition the beginning of late wisconsinan glaciation before 20 000 bp is fairly well documented none of the fluctuations in the western part of the region are accurately dated

some key features of the strong motion data from the m 6 0 parkfield california earthquake of 28 september 2004 the 2004 parkfield california earthquake was recorded by an extensive set of strong motion instruments well positioned to record details of the motion in the near fault region where there has previously been very little recorded data the strong motion measurements obtained are highly varied with significant variations occurring over only a few kilometers the peak accelerations in the near fault region range from 0 13 g to over 1 8 g one of the highest acceleration recorded to date exceeding the capacity of the recording instrument the largest accelerations occurred near the northwest end of the inferred rupture zone these motions are consistent with directivity for a fault rupturing from the hypocenter near gold hill toward the northwest however accelerations up to 0 8 g were also observed in the opposite direction at the south end of the cholame valley near highway 41 consistent with bilateral rupture with rupture southeast of the hypocenter several stations near and over the rupturing fault recorded relatively weak motions consistent with seemingly paradoxical observations of low shaking damage near strike slip faults this event had more ground motion observations within 10 km of the fault than many other earthquakes combined at moderate distances peak horizontal ground acceleration pga values dropped off more rapidly with distance than standard relationships at close in distance the wide variation of pga suggests a distance dependent sigma may be important to consider the near fault ground motion variation is greater than that assumed in shakemap interpolations based on the existing set of observed data higher density of stations near faults may be the only means in the near future to reduce uncertainty in the interpolations outside of the near fault zone the variance is closer to that assumed this set of data provides the first case where near fault radiation has been observed at an adequate number of stations around the fault to allow detailed study of the fault normal and fault parallel motion and the near field s wave radiation the fault normal motions are significant but they are not large at the central part of the fault away from the ends the fault normal and fault parallel motions drop off quite rapidly with distance from the fault analysis of directivity indicates increased values of peak velocity in the rupture direction no such dependence is observed in the peak acceleration except for stations close to the strike of the fault near and beyond the ends of the faulting

preconsolidation pressures in the battleford formation southern saskatchewan canada soft surficial unoxidized till of the battleford formation overlies hard oxidized and unoxidized till of the floral formation the difference in hardness between these two formations is the result of preconsolidation pressures that range from 1500 to 2200 kpa in the floral formation and from 350 to 750 kpa in the lower till unit of the battleford formation the upper till and clay unit of the battleford formation which represents a conformable contact between this formation and the overlying glaciolacustrine clay is normally consolidated preconsolidation of the floral formation apparently took place upglacier where the potentiometric surface for subglacial beds was 170 240 m below the ice surface the lower till unit of the battleford formation was deposited from and consolidated under stagnant ice the upper normally consolidated till and clay unit of the battleford formation was let down upon the lower till unit by ablation the calculated minimum stagnant ice thickness required for consolidation

the geotectonic environments of late proterozoic mineralisation in the southern arabian shield abstract using the results of recent research the geotectonic setting of selected mineral occurrences in the saudi arabian late proterozoic shield south of latitude 21 n is described and an initial metallogenic cycle is presented the occurrences selected are types common in the region or are economically significant they include volcanic hosted copper zinc sulfides stratabound copper in sedimentary and minor volcanic rocks zinc in sedimentary rocks and tungsten hosted by mafic plutonic rocks the copper zinc occurrences are typical of volcanogenic mineralisation they are hosted by intraoceanic volcanic arc complexes one 100 200 ma younger and geochemically more evolved than the other the stratabound copper which has some features comparable with sedimentary hosted copper deposits elsewhere developed in the lower part of a transgressive sequence in a basin marginal to the younger volcanic arc complex the sedimentary hosted zinc mineralisation belongs to a small unit of rocks accreted to the younger arc complex from a terrane east of the shield the mafic plutonic rocks hosting tungsten are part of the post tectonic pan african phase of magmatism in the region the discussion of these occurrences assumes that the region developed through the processes of ocean plate subduction plate collision and cratonisation of the resulting deformed and metamorphosed accreted rocks by the intrusion of large volumes of post tectonic pan african granitic plutons a metallogenic cycle similar to those developed for other regions of accreted arc terranes results

the denholm landslide saskatchewan part i geology the denholm landslide whose surface is composed of scarps ridges and elongated depressions is 160 m high 2000 m wide and up to 100 m thick the shear zone is in silty montomorillonitic clay of the upper part of the lea park formation and upper colorado group unit the upper cretaceous judith river formation and the quaternary empress sutherland and saskatoon groups were affected by the landslide although these sediments were fractured and gravity faulted by tension when the landslide moved they can be readily traced through the landslide particularly the upper part the scarps gravity faults ridges horsts and elongated depressions grabens are the surface expression of tension resulting from the stretching of beds during the landslide the movement of the landslide is thought to have started when the north saskatchewan spillway eroded to the level of the present shear zone about 11 000 years ago established by radiocarbon dating and is believed to have stopped in recent time during th

glacial lake saskatchewan and lake agassiz deltas in east central saskatchewan with special emphasis on the nipawin delta the nipawin delta extends eastward from the town of nipawin in east central saskatchewan the prince albert and fort a la corne deltas formed in lake saskatchewan at the mouths of the south and north saskatchewan rivers whereas the nipawin and mossy vale deltas formed in lake agassiz at the mouth of the saskatchewan river these deltas became lower in elevation and younger eastward clays beneath the nipawin and mossyvale deltas can be traced beneath the prince albert and fort a la corne deltas with little change in thickness suggesting that most of the clays beneath the nipawin and mossyvale deltas were deposited during the formation of the prince albert and fort a la corne deltas the nipawin delta formed between 10 200 and 9500 bp the campbell strandline emerson phase was the shoreline of the nipawin delta the mossyvale delta formed about 9500 bp the surface of the mossyvale delta mccauleyville level is about 40 m below the surface of the nipawin delta campbell level

structural and litho tectonic controls on neoproterozoic base metal sulfide and gold mineralization in north hamisana shear zone south eastern desert egypt the integrated field structural landsat 7 etm and aster data approach abstract the hamisana shear zone hsz is an excellent example of high strain shear belt of the neoproterozoic arabian nubian shield ans situated in a position between three major pan african terranes se desert gabgaba and gebeit terranes the north hamisana shear zone area nhsz cuts across sequences of island arc related metasediment metavolcanic which are structurally overlain by ophiolitic nappes and intruded by a number of granitoids and gabbroic rocks although it is interesting geological tectonic setting for base metal sulfide and gold ores there is a lack of detailed studies on structure geology and mineralization in this area which considered as poorly mapped remote region not only in egypt but also in sudan for these reasons we integrated image transformation methods include principal components analysis pca band ratios br false color composite fcc and filtering on the spectral bands of two distinct datasets etm and aster for detailed mapping of the nhsz area spectral data fusion with structural data analysis and field observations provide a better understand of the temporal and spatial relationships between the litho tectonic units and regional tectonic setting in the course of controls on base metal sulfide and associated gold mineralization merging these different data sources in the study area suggests that the base metal sulfide and associated gold mineralization are restricted to quartzites member of island arc related metasediments and mostly controlled by d3 deformational event main hsz deformational event this event characterized by transpressional stress regime with 1 trending e w and 3 trending n s activated conjugate nnw sinistral and nne ssw dextral strike slip faulting likely during syn tectonic granodiorite emplacement

dam induced and natural channel changes in the saskatchewan river below the e b campbell dam canada abstract the e b campbell dam on the saskatchewan river east central saskatchewan was constructed in 1962 forming tobin lake 2 2 billion m3 capacity which today impounds most fluvial sediment and disrupts normal outflow patterns thirty five kilometers below the dam the river diverts into a 500 km2 belt of alluvial sediment initiated by an avulsion 140 years ago rejoining the parent channel 108 km from the dam effects of the dam on channel geomorphology including the historical channel reach i and the more recent avulsion affected channels were investigated by pre and post dam cross section surveys combined with grain size and bedload measurements twenty three sites were surveyed at least twice and 14 were resurveyed annually in 2003 2014 except 2007 during which significant floods occurred in 2005 2011 and 2013 all channel cross sections up to 81 km below the dam have coarsened and enlarged since closure resulting in excavation of 35 4 106 m3 of channel perimeter sediment since 1962 the most proximal segment is armored and has changed little in recent years since 2003 channel enlargement has been greatest in the 35 81 km segment between the avulsion site and the forks reaches ii iii manifested as widening and deepening enlargement rates were greatest during the three floods and the paucity of bedload has prevented degraded portions of the channel bed from replenishment following flooding budget calculations based on bedload measurements and channel cross section areas suggest that 30 years would be required to replace the sediment removed between 2003 and 2014 assuming all available bedload remains in the affected reach dam effects appear to be absent or uncertain beyond 81 km a multichanneled region of varied stages of activity reach iv recombining and eventually rejoining the parent saskatchewan river channel at km 108 reach v sediment evacuated from reaches i iii is sufficient to sustain modest aggradation in some distal portions of the avulsion belt including the mossy delta but little bedload is returned to the parent channel dam induced sediment starvation is speeding the rate at which a single dominant channel is evolving between the avulsion site and rejoined parent a process that will likely shift the patterns of flood inundation in the future

the application of aster remote sensing data to porphyry copper and epithermal gold deposits abstract this paper reviews the performance characteristics of the advanced spaceborne thermal emission and reflection radiometer aster remote sensor the standard data products and applications of the most recently developed image processing methods applied to aster data as a tool for mapping hydrothermal alteration mineral zones associated with porphyry copper and epithermal gold mineralization and related host rock lithology hydrothermal alteration zones associated with porphyry copper deposit such as phyllic argillic and propylitic mineral assemblages can be discriminated from one another by virtue of their spectral absorption features which are detectable by aster swir spectral bands the identification of the phyllic zone is important in the initial stages of porphyry copper exploration as an indicator of high economic potential for copper mineralization two new crosstalk corrected aster swir reflectance products including ast 07xt and refl1b are more reliable than previous aster data products for regional mineral mapping without use of additional spectral data from the site for calibration four types of algorithms were used to extract spectral information of aster data 1 band ratio indices and logical operator based methods 2 principal components and enhancement based methods such as principal component analysis pca and minimum noise fraction mnf 3 shape fitting based algorithms such as spectral angle mapper sam matched filtering mf and mixture tuned matched filtering mtmf and 4 partial unmixing methods such as linear spectral unmixing lsu and constrained energy minimization cem this review emphasizes that the logical operator algorithms can be best suited for hydrothermal alteration mineral mapping including phyllic and argillic zones associated with porphyry copper mineralization in a regional scale shape fitting based and partial unmixing algorithms are robust and reliable for detecting particular mineral and mineral assemblages in hydrothermal alteration zones in a district scale consequently the integration of the results derived from the logical operator shape fitting based and partial unmixing algorithms can produce comprehensive and accurate information for the reconnaissance stages of copper and gold exploration at both regional and district scales all of the methods and applications reviewed in this paper demonstrate the utility of aster data for exploration of the porphyry copper and epithermal gold deposits around the world

near fault earthquake ground motion simulation in the grenoble valley by a high performance spectral element code near fault effects are known to produce specific features of earthquake ground motion such as long period velocity pulses and directivity that cannot be predicted by numerical approaches involving vertical plane wave propagation in one dimensional 1d soil models that are used as a standard in engineering applica tions coupling near fault conditions with site effects induced by complex geological structures such as deep alluvial basins or steep topographic irregularities further con tributes to the complexity of earthquake ground motion and to the difficulty to provide reliable predictions without making use of large size 3d numerical simulations in this article we present a parametric study of the seismic response of the grenoble valley france due to an mw 6 seismic source at some 10 km epicentral distance from the urban area that was carried out in the framework of an international benchmark for earthquake ground motion prediction the spectral element code geoelse for seismic wave propagation analyses in 3d heterogeneous media in the linear and non linear range was used for this purpose full advantage was taken of its implementation on parallel computer architectures after introducing geoelse and its parallel per formance and after introducing some of its validation benchmarks the spatial varia bility of the seismic response of the grenoble valley is quantitatively investigated taking into account two effects i the hypocenter location and ii the nonlinear soil behavior through a nonlinear viscoelastic soil model finally numerical results are compared with available data and attenuation relationships of peak values of ground motion in the near fault region based on the results of this work the unfavorable interaction between fault rupture radiation mechanism and complex geological con ditions may give rise to large values of peak ground velocity exceeding 1 m sec even in low to moderate seismicity areas it may therefore considerably increase the level of seismic risk especially in highly populated and industrially active regions such as the alpine valleys

megaflooding associated with glacial lake agassiz abstract significant baseline and episodic megaflooding from glacial lake agassiz was routed to the south east and north coasts of north america over the lake s nearly 6000 year history the five phases of lake level change were controlled by which outlet was active which in turn was controlled by ice margin position and glacioisostatic adjustment the southern outlet is the oldest and best understood outlet while successively younger outlets are progressively less understood eastern drainage synchronous with the younger dryas chronozone had been assumed by most studies but a spillway to accommodate the 90 m drop in lake level is yet to be described with the south and east outlets unable to accommodate the necessary lake level drawdown the northwest outlet has become the default outlet with arctic ocean core data supporting it however extant terrestrial data from the continent only provides data for a large flood from the fort mcmurray area closer to the end of the younger dryas coinciding with the timing of the preboreal oscillation the challenge remains to find agreement between the marine and terrestrial records uncontroversial is the geomorphic and sedimentologic evidence for flooding into and out of the lake consisting of large spillways large boulders and in places giant current ripples composed of boulders flood discharge estimates into and out of the lake range from 0 04 to 1 sv with final subglacial drainage into the tyrell sea estimated at 5 sv sufficient to raise global sea level by 0 18 m and initiate the 8 2 ka stadial

the petrofka landslide saskatchewan both abutments and all piers of the petrofka bridge are on a landslide the bridge has performed satisfactorily for 23 years indicating the factor of safety of the petrofka landslide is greater than unity this stability is abnormal because landslide slopes on bedrock clays shale in this region are notoriously unstable a dormant landslide is difficult to analyze because the input parameters must represent a condition of limiting equilibrium the petrofka landslide is 70 m high 880 m long 3000 m wide and up to 100 m thick the shear zone is in highly plastic montmorillonitic clays in an unnamed formation of probable tertiary age the upper cretaceous lea park judith river and bearpaw formations and the unnamed formation underly the landslide and are restricted to a collapse structure resulting from dissolution of devonian evaporites a retrogressive mechanism developed as valley downcutting progressed the pore water pressures could be estimated from the hydraulic head in the artesian aquifer of th

island arcs and their role in the evolution of the western arabian shield abstract two northeast trending late precambrian ensimatic island arc systems in western saudi arabia are described each displays lithotec tonic provinces that conform to those found in modern examples of plate convergence the younger hijaz arc system 800 700 ma contains a thick fore arc sequence of al ays group turbidites overlying an accretionary prism of metamorphosed and fragmented volcanosedimentary rocks and associated ophiolites of the farri group and the al hinu formation the older asir arc system 900 700 ma is exposed at a much deeper erosional level in which only remnant arc and fore arc deposits are present it is identi fied in part by a frontal arc assemblage of abundant dioritic intrusions and high grade metamorphic rocks that are interpreted as a high t low p belt a mafic volcanic assem blage in th back are c area appears to deline ate an interarc basin situated between the at ta if frontal arc and a lithologically similar remnant arc west of bishah about 700 ma ago the hijaz island arc collided with the asir arc system along a southeast dipping subduction zone now rec ognized as the bi r umq port sudan suture epeirogeny during this period led to the crea tion of an intramassif basin in the hijaz arc system and an accretionary basin in the asir arc system these were filled by volcanic and shallow water to continental molasse depos its of the hadiyah and fatimah groups re spectively continued convergence between 700 and 675 ma ago resulted in development of the northeast trending samran fold belt the collision event marks the cessation of an episode of southeast convergence that is in terpreted as the initial phase in the progres sive eastward evolution of the arabian nubian shield introduction

the tectono metallogenic evolution of the arabian shield abstract the arabian shield comprises a group of diverse terranes accreted during the late proterozoic their boundaries are suture zones characterised by tectonised ultramafic bodies aligned within distinct orogenic belts the asir hijaz and midyan terranes consist of a series of late proterozoic immature island arcs and together form the western half of the shield in the east however the afif and ar rayn terranes have a continental affinity with the afif terrane being much older at least early proterozoic and possibly archaean metallogeny within the arabian shield is also diverse and includes cu ni and cr mineralisation associated with proterozoic oceanic crust or ophiolite arc type volcanogenic base and precious metal deposits associated with formerly active plate margins shear zone hosted mesothermal gold mineralisation related to accretionary and strike slip tectonics as well as sn w ta mo ree mineralisation associated with post cratonisation alkali granite magmatism of late proterozic to early phanerozoic age it is possible to trace a systematic evolution in metallogeny both within each terrane and throughout the craton as a whole as a function of crustal development and tectonics although the age range of rocks exposed in the shield is from early proterozoic to tertiary all known styles of primary metallogeny are associated with its cratonisation in the late proterozoic

a transient analysis of slope stability following drawdown after flooding of a highly plastic clay the stability of slopes at bridge abutments across the carrot river in east central saskatchewan was not influenced significantly by drawdown after flooding in the spring of 1995 traditional metho

mineralization controls and source of metals in the lufilian fold belt shaba zaire zambia and angola the pan african lufilian fold belt hosts extensive and rich polymetallic mineralization dominated by cu co and zn pb sulfides u oxides and noble metals stratiform vein and skarn deposits are present in the late proterozoic rocks of the katangan supergroup mineralization is regionally widespread the sedimentary basin evolution included three phases the first two characterized by rift fault controlled rapid subsidence followed by slower thermal subsidence were associated with bimodal magmatism and probably related to two thermal events the third phase reflects the onset of tectonic deformation and uplift in the southern part of the basin the stratiform mineralization emplaced before the folding of the basin is concentrated in lithologically varied permeable rocks of the roan group that underlie the impermeable rocks of the lower kundelungu group the stratiform mineralization was emplaced by convective circulation of basinal brines forced by a thermal gradient created by a wedge shaped lithosome of lower kundelungu pelitic rocks with low thermal conductivity hypabyssal igneous intrusions and volcanic and volcaniclastic rocks were the source of metals the metals were introduced to the aquifer horizons saturated with basinal brines by hydrothermal circulation associated with the hypabyssal intrusions and by compactional dewatering of a 5 000 m thick body of pelitic rocks rich in volcaniclastic material vein mineralization located on major late faults resulted from regional metamorphism driven dewatering of the folded basin the skarn metasomatic mineralization is associated with small post katangan acid intrusions and blocks of thermally rejuvenated basement details of the distribution of mineralization are stratigraphically and structurally controlled

the hepburn landslide an interactive slope stability and seepage analysis mechanisms of active landslides are continuous processes involving the dynamics of slope failure interacting with the groundwater regime this process is simulated in phases by combining stability calculations interactively with a seepage analysis to determine the factor of safety for a dormant landslide near hepburn saskatchewan the landslide is a multiple retrogressive failure with two parallel slip surfaces at different elevations the slip surfaces are in originally overconsolidated cretaceous and tertiary clays softened by shear from glaciation an artesian aquifer is present at the base of the slip surface causing saline springs at the base of the valley slope a residual effective friction angle of 6 7 with zero cohesion was found to best characterize the shear strength of the clays in the failure zone potential nets and head profiles from the seepage analysis illustrate the strong influence of changing topography on the groundwater flow system the present day factor of safety for the dormant

an assessment of the minimum timing of ice free conditions of the western laurentide ice sheet abstract this study presents an investigation of the minimum timing of retreat of the western laurentide ice sheet which covered parts of canada and the northern united states during the wisconsin glaciation the retreat of the ice sheet is poorly constrained due to low spatial resolution of chronological data that indicate ice free conditions a limitation of radiocarbon and luminescence dating methods is that it is only possible to determine the time when it is certain that ice is absent from a region which may differ substantially from the true date of ice margin retreat the minimum timing of ice free conditions is determined using a model of ice sheet retreat inferred from landforms that formed during the late stages of glaciation and extrapolating the calibrated probability distribution of chronological data in the opposite direction the analysis excludes radiocarbon samples from materials that have been shown to give artificially old ages such as bulk sediments the results of the analysis identify 55 dates that have the most impact on the model the retreat of the western laurentide ice sheet commenced by at least 15 000 cal yr bp while the minimum timing of ice free conditions between the laurentide ice sheet and the cordillera is after 11 000 cal yr bp a lack of data in the keewatin sector prevents the determination of a precise timing of ice free conditions in the last vestiges of the laurentide ice sheet the model provides a guide to where additional samples could improve chronological control on ice margin location

seismic site response for near fault forward directivity ground motions forward directivity effects in the near fault region produce pulse type motions that differ significantly from ordinary ground motions that occur at greater distances from the causative fault current code site factors are based on empirical observations and analyses involving less intense nonpulse ordinary ground motions nonlinear site response analyses with bidirectional shaking are performed using representative site profiles to quantify seismic site response effects for intense near fault motions resulting from forward directivity input rock motions are represented with simplified velocity pulses that characterize the amplitude and period of forward directivity motions results indicate that site response affects both the amplitude and period of forward directivity pulses and hence local site conditions should be considered when evaluating seismic designs in the near fault region stiff soil sites tend to amplify the peak ground velocity and increase the period of pulse type motions particularly

aster detection of chromite bearing mineralized zones in semail ophiolite massifs of the northern oman mountains exploration strategy abstract economically viable chromite deposit occurrences are widespread in the ultramafic rocks of semail ophiolite massifs of the northern oman mountains particularly in the basal dunite and harzburgite unit of the mantle section geological mapping of this region is challenging primarily due to difficult access complexity of structures and lack of resolution and areal integrity of lithological differentiation using conventional mapping techniques the present research study evaluates the discrimination and occurrence of chromites bearing mineralized zones within ophiolites by analyzing the capabilities of landsat tm and advanced spaceborne thermal emission and reflection radiometer aster satellite data using a number of selected methods including decorrelated stretching different band rationing and principal component analysis image processing techniques exist in the scientific literature the study results show that the processed vnir and swir spectral wavelength regions are promising in detecting the areas of potential chromite bearing mineralized zones within the ophiolite region and proved to be successful for mapping of serpentinized harzburgite containing chromites exploration geologists industrialists and mine owners are advised to adopt this technique and avoid the limits in filed data alone for more exploration and exploitation of areas having chromite deposits in arid region elsewhere

evaluation of very high to medium resolution multispectral satellite imagery for geoarchaeology in arid regions case study from jabali yemen abstract archaeological research of the ancient jabali silver mines 7th to 14th centuries ad in northern yemen is a multidisciplinary project covering scientific disciplines traditionally related to archaeology a geological approach and new technologies such as very high resolution remote sensing mining companies envisage the development of the jabali deposit for zinc ore some of the planned facilities particularly a large open pit will have a destructive impact on the old pits and processing heaps already damaged by recent works in the present study remote sensing is used for a detailed survey of the impact of preliminary mining works from the early 1980 s with the aim to establish archaeological remains and to prioritize areas for future ground surveys as well as for geological mapping results indicate that mapping using remote sensing in the visible to short wave infrared range has a great potential for the identification of gossans iron caps possibly related to archaeological remains the phases of work in jabali are clearly put into light by the study of a time series of landsat data very high resolution quickbird imagery appears particularly relevant for mapping most of the archaeological remnants iron caps as well as the 3d visualization of the mining site when drapped over a detailed digital elevation model

sliding displacement of flexible earth slopes subject to near fault ground motions abstracta fully coupled simplified method that incorporates soil nonlinearity is used to conduct sliding block analysis of slopes subjected to near fault pulse like and nonpulse like ground motions the effects of the ground motion pulse on the computed sliding displacements are investigated and the efficiency of various ground motion intensity measures for predicting the sliding displacement of slopes is evaluated it is shown that the slope is expected to have larger displacements over shorter time intervals when near fault ground motions have pulse like characteristics results also indicate that for cases in which the natural period of a slope is close to the period of the pulse of a recorded ground motion an equivalent wavelet pulse appropriately represents the displacement response of slopes predictive models are developed for the sliding displacement of near fault ground motions using spectral acceleration and peak ground velocity as predictive variables in addition it is shown that for certai

aster capability in mapping of mineral resources of arid region a review on mapping of mineral resources of the sultanate of oman abstract advanced space borne thermal emission and reflection radiometer aster has exclusive capability to map minerals and ore deposits and able to discriminate rock types useful for geological applications especially the improved spectral and spatial resolutions of spectral bands of the sensor are well utilized by the exploration geologists working on arid region where the surface deposits are directly exposed to the sensor without disturbances of the vegetation several fruitful research studies have been carried out to map mineral resources in arid region with inaccessible rugged mountains and deserts area where it is difficult to do conventional geological mapping these were demonstrated and documented in the scientific publications using the aster spectral bands and image processing methods this study reviews scientific literatures published on mapping of the economic mineral resources of the sultanate of oman using aster and simples image processing methods

geological control of massive sulfide mineralization in the neoproterozoic wadi bidah shear zone southwestern saudi arabia inferences from orbital remote sensing and field studies abstract this study combines new field and orbital remote sensing data to determine geologic controls on sulfide mineralization in the wadi bidah mineral district wbmd located in the neoproterozoic 900 550 ma arabian shield of southwestern saudi arabia the brittle and ductile deformation of these massive sulfide deposits and host rock reflect tectonic events occurring in the arabian shield during the neoproterozoic 900 550 ma remote sensing data were used in conjunction with gis software arcview to map lithologic units and mineral deposits analyze and define regional structural trends and establish geologic controls on sulfide mineralization orbital remote sensing data sets include scenes from landsat 7 and aster the sulfide deposits of the wbmd are found within a group of felsic volcaniclastics a marble unit within the felsic volcaniclastic group is used as a marker horizon based on the distribution of the sulfide deposits relative to the marble unit all sulfide deposits appear to be stratabound deposits have been folded and faulted into their present positions structural control of mineralization appears to be limited to post mineralization folding and shearing

the seismic response of the los angeles basin california using strong motion data recorded in the los angeles region from the 1992 mw 7 3 landers earthquake we have tested the accuracy of existing three dimensional 3d velocity models on the simulation of long period 2 sec ground motions in the los angeles basin and surrounding san fernando and san gabriel valleys first the overall pattern and degree of long period excitation of the basins were identified in the observations within the los angeles basin the recorded amplitudes are about three to four times larger than at sites outside the basins amplitudes within the san fernando and san gabriel valleys are nearly a factor of 3 greater than surrounding bedrock sites then using a 3d finite difference numerical modeling approach we analyzed how variations in 3d earth structure affect simulated waveforms amplitudes and the fit to the observed patterns of amplification significant differences exist in the 3d velocity models of southern california that we tested magistrale et al 1996 graves 1996a hauksson and haase 1997 major differences in the models include the velocity of the assumed background models the depth of the los angeles basin and the depth location and geometry of smaller basins the largest disparities in the response of the models are seen for the san fernando valley and the deepest portion of the los angeles basin these arise in large part from variations in the structure of the basins particularly the effective depth extent which is mainly due to alternative assumptions about the nature of the basin sediment fill the general ground motion characteristics are matched by the 3d model simulations validating the use of 3d modeling with geologically based velocity structure models however significant shortcomings exist in the overall patterns of amplification and the duration of the long period response the successes and limitations of the models for reproducing the recorded ground motions as discussed provide the basis and direction for necessary improvements to earth structure models whether geologically or tomographically derived the differences in the response of the earth models tested also translate to variable success in the ability to successfully model the data and add uncertainty to estimates of the basin response given input scenario earthquake source models

remote sensing for mineral exploration abstract remote sensing is the science of acquiring processing and interpreting images and related data acquired from aircraft and satellites that record the interaction between matter and electromagnetic energy remote sensing images are used for mineral exploration in two applications 1 map geology and the faults and fractures that localize ore deposits 2 recognize hydrothermally altered rocks by their spectral signatures landsat thematic mapper tm satellite images are widely used to interpret both structure and hydrothermal alteration digitally processed tm ratio images can identify two assemblages of hydrothermal alteration minerals iron minerals and clays plus alunite in northern chile tm ratio images defined the prospects that are now major copper deposits at collahuasi and ujina hyperspectral imaging systems can identify individual species of iron and clay minerals which can provide details of hydrothermal zoning silicification which is an important indicator of hydrothermal alteration is not recognizable on tm and hyperspectral images quartz has no diagnostic spectral features in the visible and reflected ir wavelengths recorded by these systems variations in silica content are recognizable in multispectral thermal ir images which is a promising topic for research

anomalous propagation of long period ground motions recorded in tokyo during the 23 october 2004 mw 6 6 niigata ken chuetsu japan earthquake unusually large 5 cm and prolonged shaking associated with long period ground motions at periods of about 7 sec were observed in central tokyo during the mw 6 6 niigata ken chuetsu earthquake of 23 october 2004 the long period ground motions caused significant resonance in high rise buildings of about 70 floors in height thus it is an urgent matter to understand the development and amplification properties of long period ground motions in tokyo associated with large earthquakes in this study we use numerous waveform records from 585 stations in a nationwide accelerometer network k net kik net and 495 intensity meters in the area around tokyo the data reveal that the long period ground motion is characterized in most part by a surface rayleigh wave generated at the northern edge of kanto basin and the surface wave is developed as propagating through a thick cover of sediments 3000 4000 m that overlies rigid bedrock to complement the observational data we conducted a large scale computer simu lation of seismic wave propagation by employing the earth simulator supercomputer with a detailed source slip model and a high resolution 3d sedimentary structural model of central japan the results of the computer simulation demonstrate that the anomalously prolonged ground shaking of the long period signal recorded in the center of tokyo occurred because of the stagnation of seismic energy resulting from the multipathing and focusing of rayleigh waves toward the bottom of the kanto basin from surrounding mountain regions with interaction to the 3d basin structure

isostatic rebound in the northwestern part of the lake agassiz basin isobase changes and overflow abstract based on new gps elevation data on the upper and lower campbell strandlines in the northwestern part of the glacial lake agassiz basin the trend of isobases representing differential glacio isostatic rebound in that region is shown to bend and assume a nearly west east orientation this differs from the northwest southeast orientation to the southeast of the study area which others had projected into the northwestern corner of the lake agassiz basin this means that there was more isostatic depression than previously thought north of 53 n the difference in slopes on reconstructed water planes of the upper and lower campbell beaches is less with these isobases which better reflects the short period of time between their formation it is likely that the change in orientation of isobases reflects the presence of a thick keewatin ice center to the north our revised west east isobase reconstruction indicates that when the lake was at the campbell beach levels 9900 9400 14c b p lake agassiz overflowed across the paleo divide at wycherley lake saskatchewan which controlled flow through the northwestern outlet of lake agassiz during part of its history overflow would not have occurred through the wycherley lake channels at this time using the old isobase projections

identification of hydrothermal alteration minerals for exploring of porphyry copper deposit using aster data se iran the nw se trending central iranian volcanic belt hosts many well known porphyry copper deposits in iran it becomes an interesting area for remote sensing investigations to explore the new prospects of porphyry copper and vein type epithermal gold mineralization two copper mining districts in southeastern segment of the volcanic belt including meiduk and sarcheshmeh have been selected in the present study the performance of principal component analysis band ratio and minimum noise fraction transformation has been evaluated for the visible and near infrared vnir and shortwave infrared swir subsystems of aster data the image processing techniques indicated the distribution of iron oxides and vegetation in the vnir subsystem hydrothermal alteration mineral zones associated with porphyry copper mineralization identified and discriminated based on distinctive shortwave infrared swir properties of the aster data in a regional scale these techniques identified new prospects of porphyry copper mineralization in the study areas the spatial distribution of hydrothermal alteration zones has been verified by in situ inspection x ray diffraction xrd analysis and spectral reflectance measurements results indicated that the integration of the image processing techniques has a great ability to obtain significant and comprehensive information for the reconnaissance stages of porphyry copper exploration in a regional scale the results of this research can assist exploration geologists to find new prospects of porphyry copper and gold deposits in the other virgin regions before costly detailed ground investigations consequently the introduced image processing techniques can create an optimum idea about possible location of the new prospects

ice shaped ring forms in western canada their airphoto expressions and manifold polygenetic origins abstract a variety of ice shaped ring forms and patterns in western canada are strikingly expressed in black and white aerial photographs the most common forms are round and oval mounds and plateaus with rim ridges around summit craters it is speculated that small clusters and large fields of them originated from dead ice supraglacial and subglacial wasting processes and often from a combination of both where shallow glacial lake waters were present other ice shaped ring features and patterns illustrated in this paper result from former and present permafrost and periglacial activity groundwater discharge and winter ice mounding and expansion that transfer fine sediment from circular orifices to their margins slush formation that creates fractal like patterns on thin ice floating on shallow snow covered lakes and wind driven icebergs and lake ice that produce circular scours on the beds of glacial lakes portions of contact airphotos have been included to show better examples of ring forms and patterns in western canada speculations on their manifold polygenetic origins are presented

regional scale demarcation of alteration zone using aster imageries in south purulia shear zone east india implication for mineral exploration in vegetated regions abstract regional scale demarcation of alterations is an important preliminary step in mineral exploration advanced spaceborne thermal emission and reflection radiometer aster imageries here have been used for alteration mapping and iron rich e g gossans area demarcation in a highly vegetated and relatively unexplored part of eastern india namely south purulia shear zone spsz the area is surrounded by mineral rich singhbhum shear zone ssz but the mineral potentiality of spsz has not yet been proven alteration mineral assemblages are comprise of iron rich alteration gossan clay alteration with varying amounts of iron content sericitization ferruginization and chloritization in this paper we discuss a few advantages and limitations of commonly used satellite image processing techniques for mineral mapping we integrate the outputs of band ratio principal component analysis pca pca loading and thresholding termed as directed pca dpca for delineating mineral potential areas our approach mapped the alteration zones with overall 74 accuracy our study leads to demarcation of 28 alteration area within a 10 km wide and 60 km long stretch of spsz two areas namely lawa 23 1 39 31 n 86 4 2 55 e and sindurpur 23 4 38 30 n 86 5 3 99 e were identified as mineral potential zone samples from those areas were studied using xrf microscope and sem with the conclusive presence of mineralization lawa is potential for hydrothermal polymetallic sulfides along with gold mineralization sindurpur is potential for secondary iron and manganese mineralization the study shows that dpca is a useful tool for aster data processing for narrowing target area in preliminary stages of exploration in vegetated zones