mapping gamma radiation and its uncertainty from weathering products in a tasmanian landscape with a proximal sensor and random forest kriging the radionuclides of potassium 40 k uranium u 238 and thorium th 232 emit from the land surface gamma radiation that is characteristic of the underlying rocks and the distribution of their weathering products in the landscape we measured the radiation along widely separated transects using a mobile proximal sensor over a 10 000 ha region of tasmania we supplemented the transect data with information from soil and geological maps and dense data from landsat and spot imagery a digital elevation model and terrain attributes on a grid at 30 m intervals so as to map the radionuclides we used a sequence of steps starting with a spatial bootstrap and random forests to predict emissions across the study area and at sampling points excluded from the bootstrap samples the predictions at the sampling points were compared with the observed values to obtain residuals which were then used to krige them at all points on the 30 m grid we combined the random forest and kriging predictions on the 30 m grid to obtain our random forest kriging predictions repeating the procedure 100 times provided confidence limits on our results and predictions the resulting maps of the radionuclides accord well with what we know of the soil lithology and topography of the region from other sources alluvial deposits with large amounts of potassium extend from the foot slopes of the great western tiers and along the flood plains of the meander river providing evidence of previous widespread weathering and deposition of the material the fertile red ferrosols roughly equivalent to ferralic nitisols in the world reference base wrb classification on the extensive tertiary basalt plateau emit little gamma radiation as a result of deep weathering and of potassium movement and accumulation down its talus slopes the maps show the complexity of the region in terms of soil lithology and terrain and they show the merits of gamma radiometry for mapping and understanding the distribution of materials in such regions copyright c 2013 john wiley sons ltd

sub basin scale dust source geomorphology detected using modis 1 the spatial and temporal variability of dust emissions from different surfaces in the lake eyre basin australia is determined using modis data for 2003 6 the sources of 529 dust plumes were classified overall 37 of plumes originated in areas of aeolian deposits 30 from alluvial deposits and floodplains and 29 from ephemeral lakes or playas at this sub basin scale the relative importance of different dust source geomorphologies varied primarily in response to sediment supply and availability and was not related to aeolian transport capacity suggesting the lake eyre basin is a supply limited system

a study of two soil development sequences located in a montane area of canterbury new zealand i clay mineralogy and cation exchange properties abstract field and laboratory data for eight soils comprising two soil development sequences in a montane area of canterbury are presented the soils are a sequence of five soils developed in fluvial deposits overlain with loess on a streamcut terrace flight the t soil sequence and a sequence of three soils developed in moraine deposits of different ages overlain by loess the m soil sequence soils in the t soil sequence represented those forming in the drier zones and soils in the m soil sequence represent those forming in the wetter zones of this montane area as the sites were selected so that soil parent materials were derived from the sedimentary rocks of the canterbury suite differences in soil development between the sequences reflected the influence of climate and vegetation factors laboratory data obtained include clay mineralogy determined by x ray diffraction and selective dissolution analysis and ph cation exchange capacity cec and effective cation exchange capacity i e cec at soil ph these data show trends related to climate vegetation history and soil age and are discussed in terms of the development of soil acidity and the dissolution and subsequent reactions of al and fe three clay mineral suites were identified the first was represented by mica trioctahedral chlorite randomly interstratified phases and dioctahedral chlorite with minor amounts of vermiculite allophane and gibbsite the second suite was similar to the first but contained significantly higher amounts of gibbsite and the third was represented by mica vermiculite and smectite in the topsoils and mica dioctahedral chlorite randomly interstratified phases gibbsite and allophane in the b horizons cation exchange properties were characterized by increasing saturation of the exchange complex by aluminium cations and increasing concentration of base cations in the topsoil

assessing the utility of visible to shortwave infrared reflectance spectroscopy for analysis of soil weathering intensity and paleoclimate reconstruction abstract visible to shortwave infrared reflectance vswir spectroscopy is a fast and efficient approach for estimation of soil properties in order to test whether soil weathering intensity can be predicted using reflectance spectra in the vswir range 350 2500 nm and to examine the efficacy of this methodology to supplement or substitute for traditional mineralogical and geochemical techniques of paleoclimate reconstruction we investigated a quaternary soil sequence at shengli in the sichuan basin of southwestern china vswir absorption bands can be characterized by geometrical parameters including position p depth d width w asymmetry as and full width at half maximum f our results indicate that spectral features in the visible to near infrared vnir 350 1000 nm range can be interpreted in terms of the presence and or concentration of individual fe oxide phases spectrally detected water is mostly bound in clay minerals and this single dominant water source facilitates interpretation of shortwave infrared swir 1000 2500 nm parameters soil spectral parameters were compared with the fe oxide mineralogy major element composition and clay mineralogy of soil samples obtained from conventional laboratory analyses strong correlations are found between vnir parameters and fe oxide mineralogy with d 900 serving as the best proxy for total ferric iron concentration p 900 and d 700 d 500 exhibit similar variation trends and relationships to the hematite hematite goethite h h g ratio of soil samples confirming their value as monsoonal weathering intensity proxies lower values of p 900 and d 700 d 500 indicate warmer and seasonally drier pedoenvironments reflecting a stronger east asian summer monsoon the utility of some swir parameters for assessment of weathering intensity declines in inhomogeneous soils e g those having vermiform structure thus spectral evaluation of weathering intensity is most effective in soils that are relatively homogeneous for which weathering degree is highly correlated to as 2200 d 2200 d 1900 and as 1400 the utility of these spectral proxies depends mainly on the mineral composition of soils and the application type i e laboratory versus field studies the application of vswir in the field e g imaging spectroscopy or is shows promise for rapid in situ mapping of weathering intensity thus providing a convenient approach to paleoclimate reconstruction in remote and inaccessible regions

mineralogical constraints on the paleoenvironments of the ediacaran doushantuo formation assemblages of clay minerals are routinely used as proxies for paleoclimatic change and paleoenvironmental conditions in phanerozoic rocks however this tool is rarely applied in older sedimentary units in this paper the clay mineralogy of the doushantuo formation in south china is documented providing constraints on depositional conditions of the ediacaran yangtze platform that host the earliest animal fossils in the geological record in multiple sections from the yangtze gorges area trioctahedral smectite saponite and its diagenetic products mixed layer chlorite smectite corrensite and chlorite are the dominant clays through the lower 80 m of the formation and constitute up to 30 wt of the bulk rock saponite is interpreted as an in situ early diagenetic phase that formed in alkaline conditions ph 9 the absence of saponite in stratigraphically equivalent basin sections 200 400 km to the south indicates that alkaline conditions were localized in a nonmarine basin near the yangtze gorges region this interpretation is consistent with crustal abundances of redox sensitive trace elements in saponitic mudstones deposited under anoxic conditions as well as a 10 difference in the carbon isotope record between yangtze gorges and basin sections our findings suggest that nonmarine environments may have been hospitable for the fauna preserved in the yangtze gorges which includes the oldest examples of animal embryo fossils and acanthomorphic acritarchs

fine resolution multiscale mapping of clay minerals in australian soils measured with near infrared spectra 1 clay minerals are the most reactive inorganic components of soils they help to determine soil properties and largely govern their behaviors and functions clay minerals also play important roles in biogeochemical cycling and interact with the environment to affect geomorphic processes such as weathering erosion and deposition this paper provides new spatially explicit clay mineralogy information for australia that will help to improve our understanding of soils and their role in the functioning of landscapes and ecosystems i measured the abundances of kaolinite illite and smectite in australian soils using near infrared nir spectroscopy using a model tree algorithm i built rule based models for each mineral at two depths 0 20 cm 60 80 cm as a function of predictors that represent the soil forming factors climate parent material relief vegetation and time their processes and the scales at which they vary the results show that climate parent material and soil type exert the largest influence on the abundance and spatial distribution of the clay minerals relief and vegetation have more local effects i digitally mapped each mineral on a 3 arc second grid the maps show the relative abundances and distributions of kaolinite illite and smectite in australian soils kaolinite occurs in a range of climates but dominates in deeply weathered soils in soils of higher landscapes and in regions with more rain illite is present in varied landscapes and may be representative of colder more arid climates but may also be present in warmer and wetter soil environments smectite is often an authigenic mineral formed from the weathering of basalt but it also occurs on sediments and calcareous substrates it occurs predominantly in drier climates and in landscapes with low relief these new clay mineral maps fill a significant gap in the availability of soil mineralogical information they provide data to for example assist with research into soil fertility and food production carbon sequestration land degradation dust and climate modeling and paleoclimatic change

lower crustal high velocity bodies along north atlantic passive margins and their link to caledonian suture zone eclogites and early cenozoic magmatism abstract in this study we use crustal scale ocean bottom seismic models to infer the presence of two types of lower crustal bodies at north atlantic passive margins type i primarily interpreted as early eocene magmatic intrusions and type ii interpreted as caledonian eclogites we discuss how these eclogites might be related to the main caledonian suture zone and other tectonic features in a conjugate north atlantic setting based on the first order approximation that p wave velocities can be related to rock strength the narrower continental margin at the southern more transect may be explained by stronger lower crust there compared with the northern voring transect this difference in strength possibly resulting in a steeper dip in the subducting baltica plate south of the proto jan mayen lineament may explain the asymmetry in extensional style observed across this lineament our interpretation locates the main suture off mid norway close to the more trondelag fault zone on the more margin along the western boundary of the trondelag platform on the voring margin and further northwards beneath the lofoten ridge the lower crustal body type i is about 60 thicker on the greenland side for both transects and its thickness along the northern transect is more than twice that of the southern transect these differences are consistent with sub lithospheric interaction between the icelandic hotspot and the continental rift oceanic accretion system around the time of continental break up

plate tectonics and the evolution of the british isles this paper is an essay on the rationalism and difficulties of the geological corollaries of plate tectonics with illustrations particularly from the geological history of the british isles there is special emphasis on the mechanics of continental lithosphere in extension when basins are formed and in convergence whereby continental lithosphere thinned in extension is shortened and restacked to form orogenic belts an upper lithosphere stress concentrating elastic lid suffers extremely complex inhomogeneous deformations above a simpler viscoelastic lower lithosphere whose deformation drives strain and displacement in the elastic lid the very nature of plate tectonics as relative motion among a multi plate mosaic of plates provides a rational semi quantitative framework for large scale geological complexity in space and time the caledonian and hercynian history of the british isles may be explained semi quantitatively in terms of plate boundary evolution but it is not possible to define unequivocal solutions the rationalism of plate tectonics is exhibited on a smaller more direct field scale by many of the complexities of ophiolite complexes such as ballantrae scotland that can be explained as the effects of the evolution of ridge ridge transforms and by diachronous deformation and sedimentation in subduction accretion prisms such as the southern uplands deformational and sedimentary patterns in nw europe from triassic times to the present day resulted from a complex interaction of extensional events related to diachronous atlantic opening and compressional events related to sequential alpine shortening phases those widespread events are typical of intracontinental plate boundary systems and create great difficulties for the geologist wishing to decipher relative plate motion from geological sequences because huge areas much larger than the british isles must be analysed and synthesized before much sense can be extracted further difficulties arise from the palinspastic and preservation problems of convergent boundaries orogenic shortening telescopes and partially subducts facies belts most orogenic belts were assembled as a collage of displaced and rotated terrain elements that were subsequently flattened elongated and straightened to an apparent but deceiving simplicity therefore while plate tectonics provides a rational geological framework against which for example british basin evolution can be tested and explained we cannot yet use the geological effects of plate boundary evolution to reconstruct relative plate motion quantitatively

cenozoic postrift domal uplift of north atlantic margins an asthenospheric diapirism model postrift domal uplifts are a distinct feature of the northern north atlantic rifted margins uplifted regions southern norway finnmark svalbard northern united kingdom occur with a typical spacing of 900 km the amount of domal uplift is substantial 1 2 km thermochronological geomorphological and seismic stratigraphic data suggest a coincident neogene onset of uplift postdating north atlantic breakup and predating onset of glaciation the norwegian domes are characterized by strongly negative gravity anomalies and reduced mantle p wave and s wave velocities previous models for uplift around the north atlantic e g glacial erosion intraplate stresses secondary convection fail to explain the above characteristics we present an asthenospheric diapir model based on a rayleigh taylor instability wherein a hot icelandic asthenosphere layer meets cold cratonic lithosphere the generated asthenospheric diapirs and associated partial melting offer a viable explanation for updoming application of this model to the south norwegian dome succesfully explains most of the currently available data

kinematics of the asal rift djibouti determined from the deformation of fieale volcano because of its subaerial exposure the asal rift segment provides an exceptional opportunity to quantify the deformation field of an active rift and assess the contribution of tectonics and volcanism to rifting processes the present topography of the asal rift results from the tectonic dismemberment during the last 100 000 years of a large central volcanic edifice that formed astride the rift zone 300 000 to 100 000 years ago three dimensional deformation of this volcano has been quantified from the combined analysis of the topography and geology the analysis indicates that spreading at 17 to 29 millimeters per year in a n40 5 e direction accounts for most of the separation between arabia and somalia the small topographic subsidence relative to extension suggests that tectonic thinning of the crust has been balanced by injection and underplating of magmatic material of near crustal density the methodology developed in this study could also be applied to quantify deformation in relatively inaccessible areas where the main available information is topography or bathymetry

elastic thickness control of lateral dyke intrusion at mid ocean ridges abstract magmatic accretion at slow spreading mid ocean ridges exhibits specific features although magma supply is focused at the centre of second order segments melts are episodically distributed along the rift toward segment ends by lateral dyke intrusions it has been previously suggested that an along axis downward topographic slope away from the magma source is sufficient to explain lateral dyke propagation however this cannot account for the poor correlation between dyke opening and surface elevation in the 2005 2010 series of 14 dyke intrusions of afar ethiopia using mechanical arguments constrained by both geodetic and seismological observations we propose that the large dykes that initiate near the mid segment magma source are attracted toward segment ends as a result of a thickening of the elastic brittle lithosphere in the along rift direction this attraction arises from the difference of elastic resistance between the segment centre where the lithosphere is thermally weakened by long term focusing of melts and comparatively colder hence stronger segment ends the axial topographic gradient in magmatic rifts may be more likely explained as an incidental consequence of these variations of along axis elastic brittle thickness rather than the primary cause of lateral dyke injections

large igneous province on the us atlantic margin and implications for magmatism during continental breakup rifted continental margins commonly include sections of igneous rock more than twice as thick as normal oceanic crust explanations for this voluminous magmatic accretion during rifting include plume models1 3 which require a deep seated thermal or chemical anomaly in upwelling mantle and non plume models4 7 which call on broad shallow thermal anomalies and or rapid upwelling of mantle through the melting zone new seismic models from two transects across the continent ocean transition on the us atlantic margin8 10 confirm the presence of a 20 25 km thick igneous section here we argue that the similarity of the crustal structure on these and two previous transects spanning 1 000 km of the margin and the association of thick igneous crust with the east coast magnetic anomaly11 imply that the thick igneous section extends along the entire margin and may have a volume of as much as 3 2 106 km3 the distribution of volcanic and plutonic rocks details of the seismic structure and lack of independent evidence for a hotspot are difficult to reconcile with plume models and suggest that non plume processes created the thick igneous crust

the lebombo monocline and associated feeder dyke swarm diagnostic of a successful and highly volcanic rifted margin abstract as part of the karoo large igneous province lip the 700 km long and 182 ma old lebombo monocline outcrops inland of a younger mozambique lowland cover that separates it from the indian ocean detailed mapping of a particularly well exposed olifant river traverse across this monocline correlates basaltic and rhyodacitic lava units within the lebombo group to at least three hosted generations of intrusions within the monocline parallel northern lebombo dyke swarm implying that a much denser feeder dyke swarm is covered by younger flows measured attitudes and thicknesses of up to 197 lavas and 791 dykes statistically quantify a structural cross section from which a properly weighted lava log of nearly 5 km basalts inter bedded with an overlying 3 5 km of rhyodacites is constructed the geological section is compatible with a slightly deeper sub lava section through the innermost 30 km s of a relatively narrow east greenland margin to which the lebombo monocline can be rigorously compared in both cases field relationships are consistent with early tectonic extension being overwhelmed by dyke dilation within margin parallel swarm segments that may have been injected laterally from central magma chambers thus it is argued that the lebombo monocline is part of a successfully rifted margin that furthermore belongs to a distinct class of highly volcanic and relatively narrow margins which only form proximal to classical triple rift lip centers where an elevated magma flux sustains a magmatic mode of extension for the karoo lip this conforms with 1 a tight gondwana reconstruction of africa with antarctica 2 successful breakup during intense 182 ma emplacement of the lebombo group 3 triple rift formation together with a short lived 181 178 ma okavango dyke swarm and 4 anomalously thick igneous crust formation during continued 2 5 cm yr separation into a loose 155 ma plate configuration of africa and antarctica

magma flow directions of shallow dykes from the east greenland volcanic margin inferred from magnetic fabric studies abstract the role played by plume generated crustal magmatic complexes in the segmentation of volcanic margins is highlighted by a preliminary study of magma flow directions in shallow intrusives from the east greenland volcanic margin we investigate the magmatic texture using anisotropy of magnetic susceptibility for eight dykes of tholeitic affinity belonging to a dyke swarm associated with the tertiary opening of the north atlantic ocean the thickness of the sampled dykes ranges from 3 to 37 m the dykes are of doleritic texture and contain up to 12 of opaque minerals and 35 of plagioclase laths dykes showing a magnetic foliation plane within the dyke plane i e a magnetic fabric usually attributed to magmatic processes represent 40 of the samples from the studied swarm these dykes have a low degree of anisotropy and their ellipsoid of magnetic susceptibility is strongly oblate inverse magnetic fabrics where the maximum principal susceptibility axis lies near the pole to the dyke account for 60 of the data we interpret these inverse fabrics either as alteration minerals with highly prolate ellipsoids of magnetic susceptibility or primary titanomagnetites with oblate ellipsoid of low anisotropy the flow direction is inferred for normal fabric dykes using the mirror imbrication of magnetic lineation analysis of thin sections shows a good agreement between magnetic fabric directions and phenocryst preferred orientations the inferred flow directions are predominantly horizontal throwing a new light on volcanic margin development

southeast baffin volcanic margin and the north american greenland plate separation plate breakup over plumes is characterized by the development of margins showing extensive magma production both underplated at moho level and extruded as thick piles of seaward dipping lava formations the disko svartenhuk area in west greenland is one of the few places in the world with exposed seaward dipping basalts forming a prism whose thickness increases seaward we present a quantitative tectonic study of this margin which we tentatively restored in its geodynamic position during the different stages of plate separation between greenland and north america our structural data are constrained with recently published 39ar 40ar and new and coherent 40k 40ar geochronology in dikes of different orientations the first order structure is that of a tectonically driven seaward crustal flexure linked to definitive plate breakup between greenland and baffin island during the eocene coeval with the formation of the upper part of the exposed seaward dipping volcanic prism this flexing is associated with a significant crustal stretching associated with arrays of continentward dipping normal faults this across strike structure is correlated to a fundamental along strike segmentation with the three segments adopting a zigzag strike there is a clear increase of extensional strain at the extremities of the segments eocene extension trended n060 on average in the northern and southern segments but was nw trending in the central ne trending nugssuaq segment we discuss the interpretation of such an extension perpendicular to the different margin segments from a regional point of view the n060 extension is distinct in orientation from the approximately n s trend of plate separation between north america and greenland in the baffin bay during the eocene however the extension recorded in the margin is nearly perpendicular to the obliquely spreading eocene accretion axis in the baffin bay this latter point suggests a mantle or ridge control of the development of the margin over regional far field lithospheric stress models

subaerial submarine evidence of structures feeding magma to stromboli volcano italy and relations with edifice flank failure and creep abstract structural field data including parameters of 109 sheets strike mostly n10 55 e average dip angle mostly 70 90 average thickness two peaks at 1 2 m and 4 2 m and of 14 eruptive fissures and vents as well as bathymetric and numerical data suggest that stromboli experienced the development of a volcanic rift zone across the cone summit with a tendency to widen towards the lower submarine flanks during the last 100 ka inside this rift zone intrusive sheets mostly strike ne and become more abundant more steeply dipping and thicker on approaching the rift axis this rift persistence reflects the edifice s state of stress with a nw se horizontal least principal stress on the magma intrusion paths after 13 ka ago sheets mainly intruded with a horseshoe shaped geometry in plan view along the boundaries of the northwestern unstable volcano flank where four main lateral collapses occurred during the last 13 ka they also intruded with a ne strike across the volcano summit and the northeastern volcano flank the horseshoe shaped geometry is influenced by the lateral creep of the volcano flank which provides space for intrusion along the transtensional boundaries of the unstable sector where thinner sheets were emplaced when the collapse depression was filled up by new deposits ne striking thicker dykes emplaced across the northwestern volcano flank indicating a rapid re establishment of regional tectonic forces across the cone unbuttressing due to the present sciara del fuoco depression and ongoing flank creeping can account for intrusions also inside the sciara del fuoco the latter in 2007

magmatic tectonic evolution of a volcanic rifted margin abstract many north atlantic continental margins are underlain by huge volcanic edifices near the continent ocean boundary a deep crustal hole drilled on the voring plateau odp leg 104 has provided important constraints on the initial breakup history and the subsequent margin evolution by penetrating more than 900 m of igneous rocks and interbedded sediments below a post early eocene cover the rocks constitute two distinct different volcanic series the upper series comprising a seaward dipping reflector wedge consists of transitional mid oceanic tholeiitic lava flows and thin volcaniclastic sediments dacitic flows some dikes and thicker interbedded sediments constitute the lower series the margin evolved by paleocene crustal extension accompanied by uplift and pervasive intrusion of the rift zone just prior to breakup magma from shallow crustal melts produced the lower series the upper series was constructed during an intense rapidly waning subaerial volcanic surge following breakup near the paleocene eocene transition it covers both the new oceanic crust and large areas of the continental crust the dipping wedge was formed by subsidence due to loading and thermal contraction possibly amplified by tectonism when the surge abated the injection center rapidly subsided and normal oceanic crust was formed there is a direct temporal and compositional relationship between the onshore north atlantic volcanic province and the margin volcanism compared to the transverse part of the province including the iceland hotspot which has been active over 60 m y the volcanic margins reflect a 2500 km long transient segment related to continental breakup lasting only about 3 m y the volcanic surge and uplift at breakup are related to a modest regional increased temperature at the base of the lithosphere this mode of margin formation has had important paleoenvironmental implications

the coastal flexure of disko west greenland onshore expression of the oblique reflectors there is a clear analogy between the coastal flexured basalts of the disko island w greenland and the offshore oceanward dipping reflectors otherwise observed in the volcanic margins of the thulean province our tectonic analysis suggests that the coastal flexure is of both syn magmatic and tectonic origin it is contemporaneous with dyke injection parallel to the axis of the flexure and to an increase in the extension across the area during the palaeocene the proposition that the coastal flexure of disko island is syn tectonic and syn magmatic throws new light on its origin we propose that this flexure and by extrapolation part of the plume related seaward dipping reflectors elsewhere may correspond to volcanic layers forming a roll over anticline overlying a continentward dipping detachment

high rate flexure of the east greenland volcanic margin constraints from 40ar 39ar dating of basaltic dykes abstract in the north atlantic domain the se greenland volcanic margin developed in response to continental break up at 57 54 ma progressive tilting and intrusion of dykes reflect a major tectonic seaward dipping flexing of the continental crust we report eight new ages of tilted pre flexure and vertical post flexure dykes determined by 40ar 39ar incremental heating experiments despite strong excess argon on plagioclase measured 40ar 39ar plateau and mini plateau ages of dykes from detailed step heating experiments on mineral separates appear reliable and a systematic difference of ages is found between tilted and vertical dykes in both studied areas kap wandel 66 20 n and kap gustav holm 66 40 n tilted dykes show ages of 54 55 ma whereas vertical dykes are younger with ages of 51 ma therefore it appears that the crustal flexing of the volcanic passive margin is a short duration event

imaging spectroscopy earth and planetary remote sensing with the usgs tetracorder and expert systems 1 imaging spectroscopy is a tool that can be used to spectrally identify and spatially map materials based on their specific chemical bonds spectroscopic analysis requires significantly more sophistication than has been employed in conventional broadband remote sensing analysis we describe a new system that is effective at material identification and mapping a set of algorithms within an expert system decision making framework that we call tetracorder the expertise in the system has been derived from scientific knowledge of spectral identification the expert system rules are implemented in a decision tree where multiple algorithms are applied to spectral analysis additional expert rules and algorithms can be applied based on initial results and more decisions are made until spectral analysis is complete because certain spectral features are indicative of specific chemical bonds in materials the system can accurately identify and map those materials in this paper we describe the framework of the decision making process used for spectral identification describe specific spectral feature analysis algorithms and give examples of what analyses and types of maps are possible with imaging spectroscopy data we also present the expert system rules that describe which diagnostic spectral features are used in the decision making process for a set of spectra of minerals and other common materials we demonstrate the applications of tetracorder to identify and map surface minerals to detect sources of acid rock drainage and to map vegetation species ice melting snow water and water pollution all with one set of expert system rules mineral mapping can aid in geologic mapping and fault detection and can provide a better understanding of weathering mineralization hydrothermal alteration and other geologic processes environmental site assessment such as mapping source areas of acid mine drainage has resulted in the acceleration of site cleanup saving millions of dollars and years in cleanup time imaging spectroscopy data and tetracorder analysis can be used to study both terrestrial and planetary science problems imaging spectroscopy can be used to probe planetary systems including their atmospheres oceans and land surfaces

structure of yemeni miocene dike swarms and emplacement of coeval granite plutons abstract dike swarms in the yemeni sector of the eastern margin of the red sea basin have been mapped and sampled the greatest concentration of mafic dikes occurs along the tihama coastal escarpment zone less profuse swarms lace the plateau interior the escarpment zone also hosts microgranitic dike swarms related to a chain of closely spaced miocene granite plutons dolerite irruption overlapped in time and space with this plutonism southern red sea basin evolution commenced with flood basalt eruptions upon the late proterozoic arabian craton subsequent continental rifting and crustal fissuring focussed dike swarms along a zone of coeval anatectic granites that largely blocked further flood basalt eruption immediately following this crustal fissuring diking episode severe crustal stretching and thinning led to block faulting and tilting eventually rupture near the rift axis initiated sea floor spreading the resulting crust beneath the outer parts of the red sea basin is new igneous material that has generated two layer neo continental crust

volcanism on the rockall continental margin continental break up in the northern north atlantic was accompanied by massive volcanism this produced sequences of basalt flows erupted close to sea level which are imaged as seaward dipping reflectors on seismic reflection profiles they comprise the upper 4 5 km of transitional crust in both the edoras bank and hatton bank areas of the rockall continental margin detailed surveys show that the reflectors are convex upward on dip lines but are sub horizontal on strike lines they are probably produced by aerially extensive basalt flows extruded from linear fissure vents aligned parallel to the rift axis along the rockall margin two sequences of seaward dipping reflectors occur separated by an 9outer high9 near the foot of the continental margin the landward set of basalt flows are emplaced above stretched and intruded continental crust while the seaward set span the region from highly distended continental crust to fully oceanic crust the outer high is capped by basalt flows but exhibits little coherent internal reflectivity we discuss possible origins of the outer high as a residual block of thinned and intruded continental crust or as a central volcano cut by fissure vents similar to those found in the neovolcanic zones of iceland

tectonic evolution of the greenland scotland ridge during the paleogene new constraints understanding the early history of the north atlantic ocean is made difficult by a lack of detailed tectonic information from its margins analysis of brittle deformation in the basalts of the faeroe islands constrains ages types and orientations of tectonic movements related to the north atlantic paleogene kinematic evolution three synmagmatic tectonic episodes affected the faeroe area between chrons 26r and 24 followed by postmagmatic transtension changes in trends of minimum horizontal stress are consistent with variations in the directions of north atlantic early opening and this tectonic history is correlated with the greenland drift episodes in paleogene time although transtensional strike slip faulting dominated unexpected reverse faulting with n60 e trending compression occurred between chrons 25 and 24 corresponding to a major kinematic change in the labrador sea opening

a multiresolution index of valley bottom flatness for mapping depositional areas 1 valley bottoms function as hydrological buffers that significantly affect runoff behavior distinguishing valley bottoms from hillslopes is an important first step in identifying and characterizing sediment deposits for hydrologic and geomorphic purposes valley bottoms occur at a range of scales from a few meters to hundreds of kilometers in extent this paper describes an algorithm for using digital elevation models to identify valley bottoms based on their topographic signature as flat low lying areas the algorithm operates at a range of scales and combines the results at different scales into a single multiresolution index this index classifies degrees of valley bottom flatness which may be related to depth of deposit the index can also be used to identify groundwater constrictions and to delineate hydrologic and geomorphic units

interhemispheric study of polar cap patch occurrence based on swarm in situ data the swarm satellites offer an unprecedented opportunity for improving our knowledge about polar cap patches which are regarded as the main space weather issue in the polar caps we present a new robust algorithm that automatically detects polar cap patches using in situ plasma density data from swarm for both hemispheres we compute the spatial and seasonal distributions of the patches identified separately by swarm a and swarm b between december 2013 and august 2016 we show a clear seasonal dependency of patch occurrence in the northern hemisphere nh patches are essentially a winter phenomenon as their occurrence rate is enhanced during local winter and very low during local summer although not as pronounced as in the nh the same pattern is seen for the southern hemisphere sh furthermore the rate of polar cap patch detection is generally higher in the sh than in the nh especially on the dayside at about 77 magnetic latitude additionally we show that in the nh the number of patches is higher in the postnoon and prenoon sectors for interplanetary magnetic field imf by 0 respectively and that this trend is mirrored in the sh consistent with the ionospheric flow convection overall our results confirm previous studies in the nh shed more light regarding the sh and provide further insight into polar cap patch climatology along with this algorithm we provide a large data set of patches automatically detected with in situ measurements which opens new horizons in studies of polar cap phenomena

rifted margins ductile deformation boudinage continentward dipping normal faults and the role of the weak lower crust the stunningly increased resolution of the deep crustal levels in recent industrial seismic profiles acquired along most of the world s rifted margins leads to the unraveling of an unexpected variety of structures it provides unprecedented access to the processes occurring in the middle and lower continental crust we present a series of so far unreleased profiles that allows the identification of various rift related geological processes such as crustal boudinage ductile shear and low angle detachment faulting and a rifting history that differs from the classical models of oceanward dipping normal faults the lower crust in rifted margins appears much more intensely deformed than usually represented at the foot of both magma rich and magma poor margins we observe clear indications of ductile deformation of the deep continental crust along large scale shallow dipping shear zones these shear zones generally show a top to the continent sense of shear consistent with the activity of continentward dipping normal faults cdnf observed in the upper crust this pattern is responsible for a migration of the deformation and associated sedimentation and or volcanic activity toward the ocean we discuss the origin of these cdnf and investigate their implications and the effect of sediment thermal blanketing on crustal rheology in some cases low angle shear zones define an anastomosed pattern that delineates boudin like structures the maximum deformation is localized in the inter boudin areas the upper crust is intensely boudinaged and the highly deformed lower crust fills the inter boudins underneath the boudinage pattern controls the position and dip of upper crustal normal faults we present some of the most striking examples from the margins of uruguay west africa south china sea and barents sea and discuss their implications for the time temperature history of the margins

uplift and strength evolution of passive margins inferred from 2 d conductive modelling summary post breakup vertical motions of passive margins are seen here as a result of the post rift 2 d thermal evolution a 2 d finite element numerical model is performed to evaluate both the vertical and horizontal conduction that drive the thermal evolution of continental passive margins from breakup to post breakup states initial temperature configurations corresponding to non volcanic and volcanic margins are tested and lead to different thermal evolution of the lithosphere for both margins a thermal thickening is observed in the stretched lithosphere whereas the unstretched lithosphere undergoes first 0 80 ma a thermal thinning and secondly after 80 ma a thermal thickening in comparison with non volcanic margins volcanic margins show a slower thermal thickening and a greater thermal thinning in stretched and unstretched lithosphere respectively the variations with time of lithosphere thickness are then translated into isostatic vertical movements and reveal seaward thermal induced subsidence and landward thermal induced uplift the estimated uplift reaches up to 250 m in volcanic margins and 120 m in non volcanic margins the modelled timing and amount of uplift in both margins are consistent with present day topography of volcanic passive margins that stand two to three times higher than non volcanic margins using these thermal models we finally show that the 2 d strength of the margins drastically evolves with time from a seeward dominant strength 0 80 ma toward a landward dominant strength time larger than 80 ma these lateral strength evolution could have strong effect on the flexural response of the margin through time

the nature of gold bearing palaeochannel sediments in the gidji area north of kalgoorlie western australia abstract remnants of an extensive palaeodrainage network are preserved in the kalgoorlie region of western australia as buried palaeochannels at gidji a major palaeochannel up to 60 m deep is infilled with sand and clay rich facies and overlain by younger alluvial colluvial sands and gravels aeolian sands and silts playa deposits red soils and lag materials the palaeochannel sediments consist predominantly of low crystallinity kaolinite quartz and minor smectite they contain very little muscovite illite or chlorite and can be readily distinguished from underlying in situ saprolite by their chemical characteristics particularly k al and mg al ratios low rare earth element contents and low k rb ratios these sediments were largely deposited during the mid late eocene as an homogenised mixture derived from a low relief and highly weathered pre eocene landsurface they have undergone post depositional weathering resulting in mobilisation and redeposition of iron as oxides oxyhydroxides the stratigraphy of the palaeochannel sediments indicates a change from dominantly fluvial to fluvio lacustrine conditions during deposition in areas of gold mineralisation the presence of palaeochannels complicates geochemical exploration areas of thick palaeochannel clays mask bedrock anomalies placer and supergene concentrations of gold associated with the palaeochannels can be confused with bedrock anomalies unless a multi element approach is taken the gidji palaeochannel environment contains a combination of bedrock and placer supergene gold anomalies primary bedrock anomalies generally have as sb and w as associated pathfinder elements some pathfinder elements e g as have been concentrated in ferruginous pisoliths and gravels or mechanically dispersed in near surface alluvial colluvial materials giving rise to false anomalies

mineralogical analysis of ferralitic soils in madagascar using nir spectroscopy abstract the applicability of near infrared reflectance spectroscopy nirs as tool for estimating mineral soil constituents was assessed over a wide range of highly weathered soils in madagascar the predictions were based on two types of methods chemometric methods using multivariate calibration models from partial least squares pls regressions and the use of spectral signatures of specific minerals the predictions of mineralogical properties of soils using chemometric methods were poor except for the quantification of iron oxides extracted with citrate bicarbonate dithionite cbd r2cv 0 80 soil minerals kaolinite gibbsite goethite and hematite were also estimated by nirs but with less accuracy r2cv 0 50 0 80 the predictions of kaolinite and gibbsite contents were improved by the use of the peak intensity of the first derivative spectra situated at around 2205 nm for kaolinite and 2265 nm for gibbsite the results indicate that nirs can be used as a rapid analytical technique to simultaneously estimate the main minerals of highly weathered ferralitic soils with acceptable accuracy

first in situ measurements of hf radar echoing targets 1 the sounding rocket investigation of cusp irregularities 2 ici 2 was launched into the cusp ionosphere over svalbard to investigate the production of decameter scale irregularities in the electron plasma associated with hf radar backscatter the main mission objective was to obtain high resolution measurements of decameter scale electron plasma irregularities and to quantify the growth rate for the gradient drift instability gdi at the 5 7 khz sampling rate of the absolute density measurements ici 2 has provided the first documentation in terms of absolute electron density measurements of how 10 m structures are located on km scale electron density gradients ici 2 traversed a cusp electron density structure created by ongoing soft precipitation 10 m scale irregularities were generated at km scale density gradients the estimated growth time for the gdi process was 10 50 seconds

the 3d distribution of phyllosilicate clay minerals in western victoria abstract the mineralogy of the clay fraction of soils is a major determinant of the behavior of soil conventionally these clay minerals have been determined using techniques such as x ray diffraction xrd but new complementary methods such as infrared spectroscopy can be used to rapidly and economically predict these minerals this paper presents a methodology to predict these clay minerals at high resolution that adhere to globalsoilmap gsm standards mid infrared mir spectroscopic models were formulated for clay minerals kaolinite illite and smectite using partial least squares regression plsr and legacy quantitative xrd determinations very strong models were achieved for kaolinite illite and smectite and the root mean square error of cross validation rmsecv were all

implosive earthquakes at the active accretionary plate boundary in northern iceland non double couple earthquake focal mechanisms imply a mode of seismic failure other than simple shear and movements perpendicular to the fault plane reports of such events are rare and it is controversial whether such failure can occur at depth in the earth following reports of such earthquakes from the hengill and reykjanes volcanic systems on the accretionary plate boundary in iceland1 3 a seismological survey was conducted in the krafla system iceland to explore whether such earthquakes occur elsewhere along the boundary here we report the observation of a mixed suite of focal mechanisms at krafla including shear events explosive tensile crack events such as were observed at hengill and reykjanes and implosive events these last represent cavity collapse and constitute an entirely new class of earthquake the krafla system had undergone a crustal spreading episode4 10 during the decade before the observations were made and our results indicate that immediately after such an episode the accretionary plate boundary is characterized by a heterogeneous stress regime with shear extensional and compressional sources in close juxtaposition

3d thermo mechanical modelling of a stretched continental lithosphere containing localized low viscosity anomalies the soft point theory of plate break up abstract we present numerical models of extensional visco elasto plastic 3d continental lithosphere containing weaker areas within its mantle section we aim at understanding the 3d crustal structure of volcanic passive margins that is characterized by both across strike and along strike finite strain gradients with maxima around central igneous complex or their feeding magma reservoirs it is suggested that localized hot melting zones within the lithosphere act as mechanical soft points and result in the local focusing of extension to test this hypothesis 3d thermo mechanical models of extensional continental lithosphere containing thermally induced soft points are implemented results show that crustal extension initiates and is focused over soft points in the mantle reproducing the tectonic segmentation and zig zag pattern of vpms volcanic passive margins

40ar39ar geochronology of tertiary mafic intrusions along the east greenland rifted margin relation to flood basalts and the iceland hotspot track abstract the east greeland tertiary igneous province includes the largest exposed continental flood basalt sequence within the north atlantic borderlands more than ten layered gabbro complexes including the 55 ma skaergaard intrusion and a large dolerite sill complex are the plutonic equivalents of flood basalts both lavas and intrusions have been regarded as synchronous with continental breakup at 57 54 ma we report ten new ages of the mafic intrusions determined by40ar 39ar incremental heating experiments demonstrating that the mafic intrusions formed in two distinct time windows only intrusion ii of the imilik gabbro complex the skaergaard intrusion and the sorgenfri glestcher sill complex formed at 57 55 ma coeval with the eruption of regional flood basalts and continental breakup other layered gabbro intrusions at imilik intrusion iii kruuse fjord igtutarajik nordre aputite q kap edvard holm and lilloise are distinctly younger and formed between 50 and 47 ma plate kinematic models indicate the axis of the ancestral iceland mantle plume was located under central greenland at 60 ma and subsequently crossed the east greenland rifted continental margin we propose that tholeiitic magmatism along the east greenland rifted margin largely occurred in three distinct pulses at 62 59 ma lavas and dykes 57 54 ma lavas dykes sills and some gabbros and 50 47 ma gabbros dykes and rare lavas related to discrete mantle melting episodes triggered by plume impact continental breakup and passage of the plume axis respectively this model implies northwestward continental drift of greenland relative to the plume axis by 3 9 5 0 cm yr between 60 and 49 ma consistent with estimates from seismic studies of submerged flood basalts

evidence from gravity data for focused magmatic accretion along the mid atlantic ridge gravity data from the mid atlantic ridge between latitudes 27 50 n and 30 40 n show that the accretion of magma at the ridge is focused at discrete centres along the spreading axis large positive gravity anomalies equivalent to reductions of almost 50 in crustal thickness are observed over non transform discontinuities bounding spreading segments

magmatism at rifted continental margins the intense volcanism and uplift observed on many rifted continental margins forming basaltic seaward dipping reflector sequences is accompanied by the emplacement of a thick igneous section at depth partial melting by decompression of passively upwelling asthenosphere that is hotter than normal because it is near a hotspot explains both the thickness of the new igneous crust and the initial elevation of the rifted margins

a regolith depth map of the australian continent abstract the regolith is defined as weathered in situ and transported material overlying unweathered bedrock as fresh bedrock exposures form a small proportion of the landscape regolith is common in australia and varies in depth from less than a metre in upland settings to many hundreds of metres e g the cenozoic basins because of crucial fluxes in gases water nutrients and dissolved salts and variation in permeability and connectivity knowledge of the nature and depth of regolith is important to many land based industries including agriculture and forestry the minerals industry sees regolith as a barrier to discovery of mineralised rock at depth or as a host of minerals in economic concentrations there are clearly a range of important characteristics of regolith depth and therefore the quantity of regolith is fundamental for resource inventory and biophysical modelling applications a method is described that maps the depth of regolith with estimates of mapping uncertainty to the moderately weathered saprock boundary for the whole of australia our approach draws on an extensive legacy of publically available drillhole data of variable attribute consistency and applies an environmental correlation style of digital mapping prediction that utilises relevant spatial covariates e g terrain analysis climate and gamma radiometric datasets from the original database of 350 000 records we filtered and harmonised a useable dataset of 128 000 records key predictive datasets used in the depth model included weathering intensity lithology age distance to out crop elevation and relief shallowest cover corresponded to high relief erosional landscapes and deepest corresponded to cenozoic basin sediments the final map with a ground resolution of approximately 90 m 3 arcsec was generated using 100 bootstrap model iterations the reliability of the model was assessed using measures of r square 0 38 lin s concordance 0 51 mean error 5 73 m and root mean squared error 24 56 m calculated on a withheld test dataset the regolith depth map is consistent with known areas of deep in situ weathering and accumulation of recent sediment associated with the distribution of cenozoic basins and provides a testable estimate in areas with little drilling or survey history the predictive modelling approach provides a framework to further build and improve regolith depth prediction across varying spatial scales where sufficient quality drillhole data and environmental predictors exist and set priorities for new data acquisition

on the generation of cusp hf backscatter irregularities 1 hf radar observations 630 0 nm cusp auroral emission and an ionospheric tomography scan are compared to investigate the mechanism by which radar cusp echoes are generated a collocation is reported between the equatorward boundaries of broad spectral width hf radar backscatter and 630 0 nm cusp auroral precipitation in addition the radio tomographic image reveals spatial structures in ionospheric electron density that map closely to the precipitation however the large scale horizontal gradient appears to be insufficiently steep to account alone for the rapid growth of irregularities by the gradient drift mechanism it is proposed that the initial source of the decameter scale features responsible for the backscatter may result from fine structure within the precipitation itself or alternatively from the cascade down of unstable intermediate scale gradients created in the plasma convecting poleward from the source region the latter process may explain the ongoing backscatter found poleward of the auroral band

development of volcanic passive margins two dimensional laboratory models 1 continental breakup above an anomalously hot mantle may lead to the development of volcanic margins volcanic margins are characterized by 1 thick seaward dipping lava flow sequences 2 central intrusive complexes associated with dyke swarms parallel to the coast and 3 high seismic velocity bodies in the lower crust attributable to magma underplating a conceptual model for volcanic margins development has recently been proposed based on onshore studies of the greenland margins and the british tertiary igneous province it is proposed that the long lived central intrusions are genetically linked to underlying persistent zones of mantle fusion these localized melting domains or soft spots equivalent to small mantle diapirs may locally soften the extending continental lithosphere the low viscosity diapirs would 1 localize tectonic strain and 2 feed the volcanic margin with magma thus such soft spots can control the along strike magmatic and tectonic segmentation of volcanic margins recent geophysical investigations appear to show that the along strike structure of volcanic passive margins is compatible with such a segmentation process here we present a set of scaled experiments designed to study how such localized rheological heterogeneities in the sub moho mantle may have a mechanical effect on continental breakup four layer models were constructed using sand and silicone putties to represent the brittle and ductile layers of both crust and mantle the soft spots are simulated by low viscosity silicone putty emplaced within the brittle material at the scale of the entire breakup zone the soft spots display an oceanic type strength profile defining low strength zones where continental breakup is initiated the rift orientation and segmentation are strongly controlled by the distribution of the low viscosity heterogeneities rather than by the direction of regional extension the experiments are compared with the geometry and segmentation of the onshore part of the greenland volcanic margins

magmatic ocean continent transitions abstract continental extension may or may not be coeval with significant mantle melting leading to the formation of distinct types of passive margins respectively magma poor or volcanic with distinct crustal structures especially in inter cratonic mobile areas magmatic breakup and development of volcanic passive margins vpms may postdate the early development of a non magmatic continental rift system the time span between the amagmatic and the magmatic systems may be relatively short or conversely long tens of millions years such evolution is often associated with a significant apparent asymmetry in the wideness of conjugate vpms in this paper we attempt to re interpret the structure of three paired vpms which developed close to but separately from a previous amagmatic aborted rift system due to opposite dips in major crustal detachment faults accommodating extension from sedimentary to volcanic stages those composite margins tend to individualize a fault dissected continental block here designed as l block along one of the conjugate margins in addition to the amount and distribution of amagmatic extension the time span between amagmatic and magmatic extension exerts a major structural and rheological control on the final structure of the ocean continent transitions the finite margin geometry may be erroneously interpreted as resulting from a continuous process from hyperextension to the final magmatic breakup however the early syn sedimentary extension appears in many cases to be low rate or episodic consequently the vpm final breakup of the lithosphere may shift away from the original amagmatic stretched area to the rifted margin

scintillation and loss of signal lock from poleward moving auroral forms in the cusp ionosphere we present two examples from the cusp ionosphere over svalbard where poleward moving auroral forms pmafs are causing significant phase scintillation in signals from navigation satellites the data were obtained using a combination of ground based optical instruments and a newly installed multiconstellation navigation signal receiver at longyearbyen both events affected signals from gps and global navigation satellite system glonass when one intense pmaf appeared the signal from one gps spacecraft also experienced a temporary loss of signal lock although several polar cap patches were also observed in the area as enhancements in total electron content the most severe scintillation and loss of signal lock appear to be attributed to very intense pmaf activity this shows that pmafs are locations of strong ionospheric irregularities which at times may cause more severe disturbances in the cusp ionosphere for navigation signals than polar cap patches

thermal evolution of the central atlantic passive margins continental break up above a mesozoic super plume a near synchronous early jurassic 200 ma magmatic event along the north american and west african passive continental margins can be explained by the upwelling of a large scale mantle plume super plume beneath the west african craton lateral deflection of the outflow from the plume to the ne by the ambient sub lithospheric mantle flow could account for tholeiitic basaltic magmatism extending over a distance of nearly 5000 km from brazil to southern spain continental break up is considered to occur above the stagnation streamline along which cooler material eroded from the base of the continental lithosphere by the plume is returned to the convecting mantle the dynamic model is a scaled version of that recently proposed for the hawaiian plume and satisfactorily explains the apparent lack of involvement of thermally anomalous mantle in the generation of central atlantic oceanic crust

magma flow in the east greenland dyke swarm inferred from study of anisotropy of magnetic susceptibility magmatic growth of a volcanic margin summary volcanic passive margins vpms are characterized by large volumes of melt emplaced within the lithosphere during break up processes several data and a recently proposed conceptual model of volcanic margin development suggest that vpms are fed from localized crustal zones of magma storage underlying large polygenetic volcanoes localized above diapir like instabilities of the asthenosphere we investigated the magma flow pattern within the coastparallel dyke swarm of the east greenland vpm which is the only outcropping vpm over a distance of 125 km the 44 sampled dykes are representative of the successive families of intrusions igneous petrofabrics are constrained by the measurements of the anisotropy of magnetic susceptibility the magnetic fabrics are of medium to low anisotropy p 0 flow related fabrics are recorded in 75 per cent of the sampled dykes we infer the flow directions from the imbrication geometry of the magnetic foliation planes at the dyke margins and check the results by measuring the preferred orientation of plagioclase in thin sections cut in the magnetic principal planes due to probable fabric superposition the magnetic lineation represents the zone axis for the distribution of magnetic foliation plane we obtained 23 reliable flow directions that are predominantly horizontal and directed away from identified crustal reservoirs this flow pattern supports the proposed model of vpm growth and emphasizes the localized nature of the magma sources in the mantle the entire flood basalt sequence appears to have been fed by a restricted number of crustal reservoirs and associated dyke swarms

did yemeni tertiary granites intrude neck zones of a stretched continental upper crust we demonstrate that the miocene alkali granites of yemen which emplaced along the great escarpment are contemporaneous with the stretching of the southern red sea continental crust there is a gradient of miocene extension towards the granites as well as a change of the geometry of tilted blocks around them geometrically most of these granites seem to be emplaced passively in the necked areas of a stretched continental crust these necked areas correspond to previous syn plume oligocene nnw sse to n s trending areas of localized extension marked by basaltic dyke swarms these early extensional areas were associated with the emplacement of the flood basalt volcanic pile and were probably localized over large basement discontinuities

lithology and soil relationships for soil modelling and mapping abstract relationships between parent material and soil are not well understood and generally only reported in qualitative form we present a classification of parent material for pedologic purposes which includes twelve lithology classes based on mineralogical and chemical composition the relationships of these lithology classes with six key soil properties soil organic carbon ph cation exchange capacity sum of bases total p and clay were examined in a case study over new south wales australia we used multiple linear regression random forest and cubist tree models based on a soil dataset of over 3200 points semi quantitative estimates are derived of change in these soil properties with a change in lithology class and an associated silica index for example a 22 relative decrease in soil organic carbon with each 10 rise in silica broadly equivalent to a change from shale to granite assuming other factors remain constant parent material covariates are essential for the effective modelling and mapping of soil properties widely available lithology data have the potential for greater use in digital soil modelling and mapping dsmm programs we compared the performance of the classified lithology data with other continuous geophysical parent material covariates such as gamma radiometrics in digital soil models and maps over nsw the lithology covariate was demonstrated to exert the greatest influence on all six soil properties coming well ahead of all geophysical parent material and other environmental covariates validation statistics demonstrated strong improvement in both model and map quality when the lithology covariate was included for example lin s concordance for the cubist sum of bases model rose from 0 46 with no parent material covariates to 0 58 with the continuous geophysical covariates to a high of 0 77 when lithology was also used the improvement was typically slightly less marked in the final digital maps than for the calibration models probably due to the lower reliability of the lithology grid derived from broad scale polygonal geological and soil data a process is suggested for the application of lithology data into dsmm programs despite the potential drawbacks of using polygonal data properly organised categorical lithology data can be a strong covariate to complement other continuous geophysical data sources in dsmm programs particularly where reliable and fine scale geological and soil data are available