crustal structure and surface zonation of the canadian appalachians implications of deep seismic reflection data in 1986 1181 km of marine seismic reflection data was collected to 18 20 s of two way traveltime in the gulf of st lawrence area the seismic profiles sample all major surface tectono stratigraphic zones of the canadian appalachians they complement the 1984 deep reflection survey northeast of newfoundland together the seismic profiles reveal the regional three dimensional geometry of the orogen three lower crustal blocks are distinguished on the seismic data they are referred to as the grenville central and avalon blocks from west to east the grenville block is wedge shaped in section and its subsurface edge follows the form of the appalachian structural front the grenville block abuts the central block at mid crustal to mantle depths the avalon block meets the central block at a steep junction that penetrates the entire crust consistent differences in the seismic character of the moho help identify boundaries of the deep crustal blocks the moho signature varies from uniform over extended di

a volumetric approach for the resistivity response of freshwater shaly sandstones the dc electrical response of freshwater saturated shaly sandstone is analyzed on the basis of effective volume conductivity concepts for a concentrated mixture of solid grains in a continuous electrolyte the bulk conductivity of this model is physically controlled by 1 the effective porosity and the average electrical tortuosity of its free pore electrolyte and 2 the amount and concentration of bound water that coats charged solid surfaces mainly of clays and a corresponding averaged electrical surface tortuosity the latter is combined in an equivalent volume conductivity that is mainly due to the electrical double layers of charges developed at the clay electrolyte interfaces analytical expressions based on effective medium and general mixture theories are developed to describe both the whole rock conductivity and the specific conductivities of its constituent elements the derived equations for the bulk conductivity of the system describe with sufficient precision experimental core dat

paleozoic laurentia gondwana interaction and the origin of the appalachian andean mountain system laurentia the rift bounded precambrian nucleus of north america may have broken out from a neoproterozoic supercontinent between east and west gondwana several lines of evidence suggest that the appalachian margin of laurentia subsequently collided with the proto andean margin of the amalgamated gondwana supercontinent in different relative positions during early and mid paleozoic time in route to final docking against northwest africa to complete the assembly of pangea hence the appalachian and andean orogens may have originated as a single mountain system the overall hypothesis retains the same paleomagnetic and paleobiogeographic controls as previous global reconstructions for the paleozoic era laurentia gondwana collisions may help to explain contemporaneous unconformities in the paleozoic sedimentary cover of the laurentian gondwanan and baltic cratons

nature and evolution of the eastern margin of lapetus geochemical and isotopic constraints from siluro devonian granitoid plutons in the new brunswick appalachians in the gander zone ordovician to devonian metaluminous to slightly peraluminous plutons with within plate affinities intrude a lower paleozoic metasedimentary package during the siluro devonian end t and 18o values of the metasedimentary rocks would have been about 7 to 8 and 10 to 14 respectively granitoid end t values range from 0 3 to 4 2 18o values lie between 6 6 and 10 4 and published pb isotopic compositions are radiogenic 207pb 204pb 15 65 end t values of associated silurian gabbros are somewhat positive 1 2 to 2 3 some plutons exhibit evidence for comingling with this mafic component potential source materials include enriched mantle supracrustal and infracrustal sources although some constraints can be put on the first two sources the nature of infracrustal material is difficult to evaluate heterogeneous data obtained from silurian plutons can be explained by crust mantle mixing if some plutons contain a significant mantle component then mesoproterozoic o

slab breakoff a model for syncollisional magmatism and tectonics in the alps slab breakoff is the buoyancy driven detachment of subducted oceanic lithosphere from the light continental lithosphere that follows it during continental collision in a recent paper davies and von blanckenburg 1994 have assessed the physical conditions leading to breakoff by quantitative thermomechanical modeling and have predicted various consequences in the evolution of mountain belts breakoff will lead to heating of the overriding lithospheric mantle by upwelling asthenosphere melting of its enriched layers and thus to bimodal magmatism breakoff will also lead to thermal weakening of the subducted crustal lithosphere thereby allowing buoyant rise of released crustal slices from mantle depths in this paper we present a test of this model in the tertiary evolution of the european alps in the alps both basaltic and granitoid magmatism occur between 42 and 25 ma following the closure of oceanic basins by subduction and continental collision the granitoids are now well established to result from mixing of basalt with assimilated continental crust to identify the tectonically crucial origin of the partial mantle melts we have compiled all published geochemical and isotopic data of numerous mafic dykes occurring throughout the whole alpine arc their trace element and isotopic composition suggests that they have been formed by low degree melting of the mechanically stable lithospheric mantle we see no evidence for melting of asthenospheric mantle it was thus not decompressed to depths shallower than 50 km once initiated rapid lateral migration of slab breakoff will result in a linear trace of magmatism in locally thermal weakened crust this explains why all alpine magmatic rocks intruded almost synchronously along a strike slip fault the periadriatic lineament a compilation of ages from penninic high pressure rocks subducted to depths of up to 100 km shows that subduction took place at circa 55 40 ma followed by uplift at 40 35 ma from the short time interval between their uplift and the onset of magmatism we infer that both processes have been induced by the breakoff the slab breakoff model fulfills its predictions in the case of the alps and therefore supports the assumptions made in the theoretical model on a geological basis we believe that the characteristic association of magmatic activity with the return of high pressure rocks to the surface allows the identification of this process in the earth s mountain belts

granite petrogenesis in the gander zone ne newfoundland mixing of melts from multiple sources and the role of lithospheric delamination silurian to devonian granites within the gander zone of the appalachian central mobile belt in northeastern newfoundland formed adjacent to the former gondwanan continental margin following terminal closure of the iapetus ocean comparison of geochemical and isotopic characteristics of the granites with their host migmatites and metasediments amphibolite and orthogneiss constrain their potential source nd and sr isotopic compositions indicate that no single source or binary mixing product could have produced the granites instead we show that they result from multicomponent mixing involving a contribution from unexposed crystalline basement mantle or underplate and variable contamination by supracrustal host rocks the timing and composition of granite magmatism do not exhibit collisional orogenic subduction related or continental rifting characteristics hence we relate magmatism to lithospheric melting following delamination of an orogenic keel this process provides the influx of mantle derived magma into fertile crust and hence promotes lower crustal melting and primary magma mixing

p wave anisotropic tomography of the crust and upper mantle under hokkaido japan abstract we determined a 3 d anisotropic velocity structure beneath hokkaido in northern japan using a large number of first p wave arrival times the travel time inversion is parameterized with an isotropic component and two anisotropic parameters for each grid node by assuming p wave azimuthal anisotropy with hexagonal symmetry axis distributed horizontally the geometries of the conrad and moho discontinuities and the upper boundary of the subducting pacific plate are taken into account in the model our results show that low velocity zones exist beneath active arc volcanoes in the crust and in the central portion of mantle wedge above the high velocity pacific slab which are similar to the previous tomographic images p wave anisotropy is revealed in the crust mantle wedge and the subducting pacific slab in the upper crust the anisotropy is possibly caused by microcracks and cracks in the lower crust the anisotropic structure is different from that in the upper crust and it may be affected considerably by the plastic flow deformation in the mantle wedge the fast velocity direction fvd is generally trench normal in most of the study area while it becomes trench parallel in the pacific coast areas close to the trench which agrees with the shear wave splitting results beneath the volcanic front the fvd is also trench parallel which may suggest the existence of complex 3 d mantle flow in the mantle wedge the fvd in the subducting pacific slab is nearly north south which likely keeps the original fossil anisotropy of the pacific plate formed at the mid ocean ridge or is affected by the olivine fabric transition from a type to b type fabric due to the changes in water content stress and temperature

influence of deformation and fluids on ar retention in white mica dating the dover fault newfoundland appalachians abstract white mica 40ar 39ar analyses may provide useful constraints on the timing of tectonic processes but complex geological and thermal histories can perturb ar systematics in a variety of ways ductile shear zones represent excellent case studies for exploring the link s between dynamic re neo crystallization of white mica and coeval enhanced fluid flow and their effect on 40ar 39ar dates white mica 40ar 39ar dates were collected from compositionally similar granites that record different episodes of deformation with proximity to the dover fault a terrane bounding strike slip shear zone in the appalachian orogen newfoundland canada 40ar 39ar data were collected in situ by laser ablation and by step heating single crystals results were compared to each other and against complementary u pb zircon and monazite and k ar fault gouge analysis although step heat 40ar 39ar is a widely applied method in orogenic settings this dataset shows that relatively flat step heat 40ar 39ar spectra are in contradiction with wide spreads in in situ 40ar 39ar dates from the same samples and that plateau dates in some cases yielded mixed dates of equivocal geological significance this result indicates that the step wise release of ar from white mica likely homogenizes and obscures spatially controlled ar isotope reservoirs in white mica from sheared rocks in contrast in situ laser ablation 40ar 39ar analysis preserves the spatial resolution of 40ar reservoirs that have been variably reset by deformation and fluid interaction this study therefore suggests that laser ablation is the best method for dating the timing of deformation recorded by white mica final interpretation of results should be guided by microstructural analysis estimation of deformation temperature chemical characterization of white mica and complementary chronometers overall the dataset shows that granitic protoliths were emplaced between 430 and 422 ma u pb zircon high strain deformation along the wing pond shear zone occurred between ca 422 405 ma u pb monazite and 40ar 39ar subsequent patchy ar loss in white mica occurred locally during low t shear

sm nd studies of archaean metasediments and metavolcanics from west greenland and their implications for the earth s early history metasedimentary and metavolcanic rocks from the archaean of west greenland have been examined for evidence of crustal components greater than 3 8 ga in age and for their compatibility with the presently adopted bulk earth sm nd parameters sm nd isotopic data have been obtained for the garbenschiefer metagabbro unit metasediments from the isua supracrustal belt gneisses interior to the isua belt and metasediments from the malene supracrustal belt using estimates of emplacement age t of between 3 77 and 3 67 ga for the parental volcanics to the garbenschiefer unit initial143nd 144nd ratios yield positiveendt values between 1 0 and 3 1 relative to the chur parameters for seven out of eight samples model sm nd ages for the isua gneisses and metasediments are only compatible with their estimated stratigraphic ages if their sources were ca 2end relative to chur at those times similarly model sm nd ages for the malene samples are only compatible with stratigraphic age constraints when based on a source evolution with positiveendt implications of these results for the early development of the earth s mantle are discussed

geochemical and isotopic characteristics of granitoids of the avalon zone southern new brunswick possible evidence for repeated delamination events nd o and pb isotope data from southern new brunswick suggest that 625 to 360 ma granitoid plutons contain a major juvenile component and small amounts of middle proterozoic or older crustal material plutons fall into four major age groups 600 630 540 560 422 430 and 367 396 ma the first and third groups can be related to subduction in other parts of the appalachian orogen but most of the second and fourth magmatic pulses have lithologic associations and chemistry not readily reconciled to subduction the timing and volume of magmatism presence of mafic end members and juvenile signatures in the plutons suggest that crustal delamination may have been involved little evidence exists for extensive middle proterozoic or older continental crust beneath the avalon zone which consists mainly of late proterozoic continental margin arc material intruded by younger granitoid plutons that include a major mantle component this differs from contiguous gander and meguma zones in which plutons contain a ma

estimation of aquifer hydraulic parameters from surficial geophysical methods a case study of keritis basin in chania crete greece summary knowledge of aquifer parameters is essential for the management of groundwater resources conventionally these parameters are estimated through pumping tests carried out on water wells few boreholes may be available and carrying out pumping tests at a number of sites may be costly and time consuming the application of geophysical methods in combination with pumping tests provides a cost effective and efficient alternative to estimate aquifer parameters a geophysical method is used to obtain aquifer characteristics that are estimated through the pumping tests a correlation is established between these parameters at other sites where pumping has not been carried out in this way the entire investigation area could be covered to characterize an aquifer system this study has been carried out in the keritis basin in chania crete greece where the aquifer characteristics are required for the management of groundwater in the region

a grain conductivity approach to shaly sandstones the effects of clay conduction on the electrical behavior of shaly sandstones at low frequencies are analyzed by considering self similar mixtures of conductive grains as representative of these porous rocks an essential step in this model is the representation of the surface conductivities of the clay platelets by an equivalent volume conductivity based on their pattern of occurrence the clays are treated either as a continuous coating over the sand grains or as individual detrital grains mixed with a nonconductive mineral matrix in the first case the solids are modeled as layered conductive particles taken as spheres to a first approximation in the second case we generalize from the results of a three component self similar mixture of spherical particles for linear approximations the models are described by expressions quite similar to the frequently used waxman smits and dual water equations but dependent upon the clay type concentration and its distribution in the rock the models are written in terms of geometric parameters readily available from well log measurements the derived analytical expressions are successfully applied to describe a set of available experimental core and geophysical log data the results clearly demonstrate the applicability of the equations to well log interpretation as a practical procedure for computing formation factors and shaliness of argillaceous sandstones

induced polarization of shaly sands equations have been developed that relate induced polarization ip in shaly sands to measurable petrophysical parameters the induced polarization process has been modeled in terms of two mechanisms clay counterion displacement and membrane blockage the resulting equations can be used to determine shaliness brine conductivity and oil saturation from in phase and out of phase conductivities laboratory measurements have confirmed the ip dependence on these variables as well as on temperature

sm nd isotopic geochemistry of precambrian to paleozoic granitoid suites and the deep crustal structure of the southeast margin of the newfoundland appalachians in the eastern central mobile belt of the newfoundland appalachians late precambrian basement inliers have end from 3 to 2 but cambro ordovician metasedimentary rocks have initial end below 7

granite magma generation ascent and emplacement within a transpressional orogen crustal thickening during transpressive orogenesis may produce anatectic granites which may then localize deformation leading to transcurrent movement granites may be transported from sites of generation through the mid crust in dyke like channelways within relatively narrow strike slip shear zones which link to major fault zones in the upper crust extensional jogs within fault systems provide developing sites for the assembly of plutons from magma arriving from below the model is based upon observations from the cadomian belt of nw france which exposes sections through middle and upper levels of the late precambrian crust within different elements of the orogen the mechanism provides a favourable alternative to diapirism and explains the common collocation of granites and shear zone fault systems within orogenic belts

lithoprobe onshore seismic reflection transects across the newfoundland appalachians vibroseis seismic reflection data have been recorded to 18 s two way traveltime along three transects across the island of newfoundland the upper crust has both steep and subhorizontal reflectors consistent with a ramp flat style of deformation whereas the middle and lower crust are largely free of regional flats reflectors descend through ca 20 km of vertical section in the middle and lower crust to flatten into the moho or perhaps cut through it in places the moho is interpreted to be no younger than the dipping reflectors reflection fabrics interpreted to be indicators of dominantly mid ordovician to mid silurian strain show consistent orientations among the transects and divide the crust into two blocks a northwestern block is characterized by upper and middle crustal reflectors dipping mostly southeast at variable angles this block is underlain to the southeast by supposedly younger and dominantly northwesterly dipping reflectors that define a northwest tapering wedge shaped block floored

deep crustal and local rheological controls on the siting and reactivation of fault and shear zones northeastern newfoundland the siting of a c 25 km wide transpressive high strain zone at the eastern margin of the gander zone of ne newfoundland corresponds to the trace of a fundamental contact between two gondwanan basement blocks displaced sinistrally relative to one another during silurian orogenesis changes in plate motion during the devonian led to kinematic reversal and reactivation of the shear zone and at high structural levels the development of a major brittle ductile fault system at a local scale within the silurian ductile high strain zone the focus of deformation and shifts in siting of shear were closely related to magma presence we consider that granite magmas exploited shear zones within the crust to aid ascent and in doing so enhanced local deformation cessation of magma supply and or cooling of magmas within conduits caused deformation to relocate elsewhere ne newfoundland hence provides an example of how fault shear zone siting and reactivation may be controlled by regional scale pre existing basement configuration and more localised processes affecting rheology notably plutonism

a tectonic window in central newfoundland geological evidence that the appalachian dunnage zone may be allochthonous in the through hill area of central newfoundland mafic to ultramafic complexes which preserve varying amounts of ophiolite stratigraphy mark the trace of a major fault zone that outcrops in a roughly elliptical pattern the major northeast trending axis is about 60 km and the shorter axis is about 30 km in length the most complete ophiolite stratigraphy is preserved in the coy pond and pipestone pond complexes which have steep dips and face east and west respectively outwards from the centre of the ellipse the ophiolitic rocks are bounded on the outside by rocks typical of the dunnage zone of central newfoundland principally lower to middle ordovician volcanic and volcaniclastic rocks interpreted to be of island arc affinity davidsville victoria lake and baie d espoir groups cold spring pond formation and upper ordovician to silurian clastic sediments botwood group the volcano sedimentary sequences are interpreted to have been deposited on the ophiolite conformably but the contacts are n

are crustal thickness variations in old mountain belts like the appalachians a consequence of lithospheric delamination comparison of moho geometry and reflection character of active collision zones like the alps with those of fossil collision zones like the appalachians lends support for the view that lithospheric delamination is both a common and fundamentally important component of collisional orogeny in particular the relative crustal thinning commonly observed beneath the internides of old collisional orogens is an expected consequence of delamination neither precollisional crustal thickness variations nor an unrelated postcollision extensional event is required to produce this feature acceptance of the delamination hypothesis in turn fundamentally alters one s view of the tectonic evolution of old collisional orogens in the case of the appalachians delamination has direct implications for the interpretation of alleghanian granites the direction of subduction leading to final closure between laurentia and gondwana and the thermal state of the lithosphere at the onset of atlantic rifting a corollary of the delamination hypothesis is that lateral reflectivity variations cannot be used to define paleogeographic terranes in the deep crust of old orogens conversely the observation that delamination leaves a distinctive geophysical imprint on the crust itself provides an important additional clue for deciphering the tectonic evolution of such regions

evaluation of groundwater potential in kabirwala area pakistan a case study by using geophysical geochemical and pump data knowledge of hydraulic parameters hydraulic conductivity and transmissivity is essential for the delineation of groundwater potential zones conventionally these parameters are measured using pumping tests carried out on boreholes however pumping tests are costly labour intensive and require a considerable amount of equipment the integration of geophysical methods with pumping tests provides efficient and cost effective alternative to calculate hydraulic parameters fifty electrical resistivity soundings were carried out in the study area using schlumberger interelectrode configuration to obtain hydraulic characteristics that are estimated through the pumping tests to apply this approach successfully sufficient number of boreholes are used part of the boreholes in which pumping tests were carried out is used for both to constrain resistivity inversions and to establish the empirical relationship between the interpreted geophysical and hydraulic parameters the rest of the boreholes without pumping tests are still used for constraining the inversions initially aquifer parameters were measured using pumping tests at 12 water wells afterwards transmissivity t and hydraulic conductivity k were correlated with transverse resistance tr and the bulk resistivity o of the aquifer at other sites where pumping tests had not been conducted in this way the entire study area was covered to assess the groundwater reserves the hydraulic properties obtained by the geophysical method fit pretty well to both the pumping and physicochemical data of the investigated area the integrated study reveals five layers i e topsoil clay clay sand sand and gravel sand and three potential zones i e high medium and low potential aquifer zones with specific ranges of t k tr and o the results suggest that in case of sparse well data the aquifer parameters can be estimated using the relations depending on the specifications of the area

relationships between syn tectonic granite fabrics and regional pttd paths an example from the gander avalon boundary of ne newfoundland abstract syn tectonic granitic plutons and their host rocks not only provide a potential wealth of information about the timing and nature of regional kinematics but also record information about thermal conditions successive syn tectonic plutons emplaced into the gander zone of ne newfoundland preserve fabric overprinting formed during cooling to regional ambient thermal conditions ambient conditions have been approximated for each pluton by careful analysis of microstructures and consideration of potential cooling histories and have illustrated regional exhumation during a tectonic reversal from silurian devonian sinistral transpression to devonian dextral transpression because the time period of emplacement is relatively short by comparison to orogenic events typically by more than an order of magnitude individual plutons may record a snap shot of the regional history by combining information from a number of plutons emplaced sequentially during a period of regional orogenesis a picture may be built up defining time temperature deformation ttd paths such information may compliment regional metamorphic pt studies in helping to establish orogenic pttd paths

electrical resistivity in support of geological mapping along the panama canal abstract dredging and widening of the panama canal is currently being conducted to allow larger vessels to transit to and from the americas asia and europe dredging efficiency relies heavily on knowledge of the types and volumes of sediments and rocks beneath the waterway to ensure the right equipment is used for their removal to aid this process a waterborne streaming electrical resistivity survey was conducted along the entire length of the canal to provide information on its geology within the confines of the canal a total of 663 line kilometers of electrical resistivity data were acquired using the dipole dipole array the support of the survey data for dredging activities was realized by calibrating and qualitatively correlating the resistivity data with information obtained from nearby logged boreholes and geological maps the continuity of specific strata was determined in the resistivity sections by evaluating the continuity of similar ranges of resistivity values between boreholes it was evident that differing geological units and successions can have similar ranges of resistivity values for example quaternary sandy and gravelly alluvial fill from the former river channel of the chagres river had similar resistivity ranges generally from 40 to 250 m to those characteristic of late miocene basalt dikes from 100 to 400 m but for quite different reasons similarly competent marine based sedimentary rocks of the caimito formation were similar in resistivity values ranging from 0 7 to 10 m to sandstone conglomerate of the bohio formation consequently it would be difficult to use the resistivity data alone to extrapolate more complex geotechnical parameters such as the hardness or strength of the substrate a necessary component for such analyses requires detailed objective information regarding the specific context from which the geotechnical parameters were derived if these data from cored boreholes and detailed geological surveys are taken into account however then waterborne streaming resistivity surveying can be a powerful tool in this case it provided inexpensive and highly resolved quantitative information on the potential volume of loose suctionable material along the gamboa sub reach which could enable large cost savings to be made on a major engineering project involving modification of one of the most important navigable waterways in the world

correlation of geoelectric data with aquifer parameters to delineate the groundwater potential of hard rock terrain in central uganda knowledge of aquifer parameters is essential for management of groundwater resources conventionally these parameters are estimated through pumping tests carried out on water wells this paper presents a study that was conducted in three villages tumba kabazi and ndaiga of nakasongola district central uganda to investigate the hydrogeological characteristics of the basement aquifers our objective was to correlate surface resistivity data with aquifer properties in order to reveal the groundwater potential in the district existing electrical resistivity and borehole data from 20 villages in nakasongola district were used to correlate the aquifer apparent resistivity e with its hydraulic conductivity ke and aquifer transverse resistance tr with its transmissivity te ke was found to be related to e by text log k text e 0 002 rho text e 2 692 similarly tr was found to be related to t by text tr 0 07t text e 2260 using these expressions aquifer parameters tc and kc were extrapolated from measurements obtained from surface resistivity surveys our results show very low resistivities for the presumed water bearing aquifer zones possibly because of deteriorating quality of the groundwater and their packing and grain size drilling at the preferred ves spots was conducted before the pumping tests to reveal the aquifer characteristics aquifer parameters to and ko as obtained from pumping tests gave values 29 424 7 m2 day 374 3 m day 9 801 1 m2 day 437 0 m day 31 852 4 m2 day 392 9 m day the estimated aquifer parameter tc and kc when extrapolated from surface geoelectrical data gave 7 142 9 m2 day 381 9 m day 28 200 0 m2 day 463 4 m day 19 428 6 m2 day 459 2 m day for tumba kabazi and ndaiga villages respectively interestingly the similarity between the kc and ko pairs was not significantly different we observed no significant relationships between the tc and to pairs the root mean square errors were estimated to be 18 159 m2 day and 41 4 m day

precise u pb zircon ages from alderney channel islands growing evidence for discrete neoproterozoic magmatic episodes in northern cadomia the northernmost exposures of rocks formed during the late neoproterozoic cadomian orogeny in the channel islands northern france region occur on alderney the island mainly comprises foliated quartz diorite once considered to be 2 ga pre cadomian basement and an undeformed basic to intermediate plutonic complex a precise age of 610 2 ma based on u pb analyses of single and small groups of zircons for the foliated fort tourgis quartz diorite demonstrates that the oldest rocks were emplaced and deformed during a cadomian magmatic event the age is virtually identical to ages from similar foliated syntectonic quartz diorite bodies on the islands of guernsey and sark and at la hague north normandy indicating that this magmatic and deformational event was regional in extent discordant zircon xenocrysts define an upper intercept age of c 2 ga indicating the presence of palaeoproterozoic basement at depth single zircons from the undeformed bibette head granodiorite give a precise u pb age of 572 1 ma this age is closely similar to that for the emplacement of the northern igneous complex of guernsey the emerging data indicate that cadomian magmatism in the northern channel islands region was not a protracted continuum but occurred during two distinct short lived events separated by c 30 40 my

an engineering site investigation using non invasive geophysical approach subsurface geological formation is essential to validate design assumptions for the construction of deep engineering structures especially in the weathered terrains the geological formation can be delineated using resistivity values through an electrical survey however the subsurface resistivity alone is ambiguous to interpret the subsurface geological units as part of an ongoing investigation to select the key methods towards this end an integrated geophysical survey through a combination of electrical resistivity tomography ert induced polarization ip magnetic method and joint profile method jpm was carried out in a weathered terrain of south huizhou china resistivity ip and magnetic data were obtained using a variety of survey parameters subsurface resistivity was calibrated with upfront boreholes lithology to constrain geological formation into four discrete layers such as topsoil cover with resistivity 2 3257 m highly weathered layer having resistivity 2 636 m partly weathered layer with resistivity range 448 1204 m and unweathered bedrock having resistivity 791 116 497 m the integration of ert with ip magnetic and jpm delineated four faults namely f1 f2 f3 and f4 and several localized fractures the weathered layer fractures and faults were marked as the weakest zones for engineering projects whereas the unweathered fresh bedrocks were identified as the most appropriate locations for the construction of deep structures in the study area the weakest zones unsuitable for engineering structures were delineated as the most appropriate places of groundwater occurrence in the studied area revealed by low resistivity ranging from 2 to 1204 m and overlapped by low chargeability less than 14 8 ms this non invasive geophysical approach suggests the most suitable locations highly significant not only for the future construction of engineering structures but also the exploitation of groundwater resources in the investigated area