use of combined digital elevation model and satellite radiometric data for regional soil mapping abstract previous reports demonstrated that data from air and spaceborne sensors are appropriate for delineation of soil patterns also many attempts have been made to use digital elevation model dem for deriving soil information however little is known about the potential use of low spatial resolution satellite and digital elevation data in small scale soil mapping a case study was conducted to assess the use of integrated terrain and advanced very high resolution radiometer avhrr databases for small scale soil pattern delineation the main objective was to test the effect of the addition of terrain descriptor data to the avhrr data set on the classification results two database were used for the study the first one was purely avhrr data and contained the five basic avhrr channels and the normalized difference vegetation index ndvi of five different dates while in the second database the avhrr data was complemented with a dem a curvature a slope an aspect and the potential drainage density layers the performance of these two databases when employed to derive soil information was compared these databases were then further processed using the discriminant analysis feature extraction dafe function which is based on a canonical analysis procedure and were then classified using the fisher linear discriminant and the echo spectral spatial classifiers based on the results it was concluded that the two reflective bands the middle infrared the two thermal bands and the ndvi provided a relatively wide range of detectable soil information the use of single images or small dimensional avhrr data sets less then 10 layers does not result in acceptable performances while the use of multispectral and multitemporal databases improved the classification performance very significantly however the purely avhrr based model could not always delineate soil variations related to terrain differences and resulted in an overall classification performance of 49 1 digital elevation and terrain descriptor data were essential in the model for achieving acceptable results in the second part of the study an integrated avhrr terrain database was used where five terrain layers were added to the 30 avhrr channels two different spatial resolutions were compared 500 m and 1 km respectively the use of elevation slope aspect and curvature as differentiating criteria often lead to a satisfactory result in terrain characterization particularly in large scale mapping however with those variables extracted from dem of physiographically complex areas e g where plain areas and mountainous hilly regions occur together in the same study often lose their ability to delineate soil variations of the level lands beyond these terrain descriptors we implemented a new function called potential drainage density pdd to improve the performance of the model on the plain areas the classification accuracy of the integrated avhrr terrain database was improved significantly over the case when only avhrr data was in the model the classification performances of the three different resolution images were 87 3 for the 500 m resolution image and 70 1 for the 1 km resolution image

the tertiary structural and thermal evolution of the central alps compressional and extensional structures in an orogenic belt the western alpine arc has been created during the cretaceous and the tertiary orogenies the interference patterns of the tertiary structures suggest their formation during continental collision of the european and the adriatic plates with an accompanying anticlockwise rotation of the adriatic indenter extensional structures are mainly related to ductile deformation by simple shear these structures developed at a deep tectonic level in granitic crustal rocks at depths in excess of 10 km in the early palaeogene period of the tertiary orogeny the main tertiary nappe emplacement resulted from a nw thrusting of the austroalpine penninic and helvetic nappes heating of the deep zone of the upper cretaceous and tertiary nappe stack by geothermal heat flow is responsible for the tertiary regional metamorphism reaching amphibolite facies conditions in the lepontine gneiss dome geothermal gradient 25 c km the tertiary thrusting occurred mainly during prograde metamorphic conditions with creation of a penetrative nw se oriented stretching lineation xi finite extension parallel to the direction of simple shear earliest cooling after the culmination of the tertiary metamorphism some 38 ma ago is recorded by the cooling curves of the monte rosa and mischabel nappes to the west and the suretta nappe to the east of the lepontine gneiss dome the onset of dextral transpression with a strong extension parallel to the mountain belt and the oldest s vergent backfolding took place some 35 to 30 ma ago during retrograde amphibolite facies conditions and before the intrusion of the oligocene dikes north of the periadriatic line the main updoming of the lepontine gneiss dome started some 32 30 ma ago with the intrusion of the bergell tonalites and granodiorites concomitant with s vergent backfolding and backthrusting and dextral strike slip movements along the tonale and canavese lines argand s insubric phase subsequently the center of main updoming migrated slowly to the west reaching the simplon region some 20 ma ago this was contemporaneous with the westward migration of the adriatic indenter between 20 ma and the present the western aar massif toce culmination was the center of strong uplift the youngest s vergent backfolds the glishorn anticline and the berisal syncline fold the 12 ma rb sr biotite isochron and are cut by the 11 ma old rhone simplon line the discrete rhone simplon line represents a late retrograde manifestation in the preexisting ductile simplon shear zone this fault zone is still active today the oligocene neogene dextral transpression and extension in the simplon area were concurrent with thrusting to the northwest of the helvetic nappes the prealpes 35 15 ma and with the jura thin skinned thrust 11 3 ma it was also contemporaneous with thrusting to the south of the bergamasc 35 5 ma and milan thrusts 16 5 ma the oligocene neogene dextral transpression in the central alps is of the same age as the thrusting to the west and southwest in the external french part and to the east in the internal italian part of the alpine arc of the western alps

metamorphic field gradients in the central alps metamorphic field gradients were determined across the entire amphibolite grade central alps c 50 100 km p t were calculated from 116 samples acquired from our own field work from samples provided to us by others and from rocks with mineral compositions described in the literature only fluid conserved equilibria were used to determine p t the use of an internally consistent thermodynamic database and mineral solid solution models makes the results robust and reduces relative errors the results are presented in contour maps temperature increases from 500 to 550 c along the limit of amphibolite grade metamorphism in the north and west to c 675 c toward the south at the insubric line near the town of bellinzona maximum recorded pressures of c 7 kbar are in a central region c 20 km north of the insubric line and decrease both to the north 5 5 kbar and south 4 5 kbar the p t results indicate that there is a relatively large area that reached conditions in the sillimanite stability field but developed neither sillimanite nor fibrolite this is interpreted as a result of kinetic constraints on nucleation and growth because of the small amounts of thermal overstep 40 c of the kyanite sillimanite phase boundary comparison of p t conditions with carbonate isograds in the region indicate that fluids present during metamorphism were not dominated by a homogeneous external source examination of the two dimensional distribution of pressure and temperature in the context of thermal and tectonic models indicates that two thermal pulses aected the central alps during the tertiary in the second heat aected only the southern parts of the area and overprinted the previously established p t gradients

soil chronosequence and geomorphology in a semi arid valley in the andes of southern peru abstract soil development particularly in relation to relative age of geomorphic surfaces was studied in a high altitude valley on the semi arid western side of the andes in southern peru seven major fluvial surfaces in the colca valley were recognized including floodplains stream terraces and fans associated with the rio colca and its tributaries soils were also briefly examined on pleistocene andesite flows within the valley and on high volcanic plateaus surrounding the valley field and laboratory work indicate that most soils on stable surfaces above the floodplain are mollisols and that there is a consistent pattern of increasing subsurface horizon development on successively higher and older fluvial surfaces from 3300 to 3800 m elevation a developmental sequence of argillic horizons duripans and carbonate accumulation is present on these fluvial surfaces soils on the oldest fluvial surfaces exhibit strongly developed argillic horizons underlain by calcic horizons and strongly cemented duripans that contain illuvial carbonate and clay substantial development of these horizons also occurs on colluvial surfaces with slopes up to at least 65 relative depths of subsurface horizons on steeper colluvial surfaces differ from those on gently sloping fluvial surfaces in that argillic horizons and duripans are amalgamated this study indicates that significant chemical weathering and strong subsurface pedogenesis occur in high altitude mountainous environments within the tropics in contrast to findings at high altitudes in other climatic zones

coesite and pure pyrope in high grade blueschists of the western alps a first record and some consequences a pyrope quartzite originally described by vialon 1966 from the dora maira massif was resampled and reinvestigated garnet up to 25 cm in size phengite kyanite talc and rutile are in textural equilibrium in an undeformed matrix of polygonal quartz the garnet is a pyrope almandine solid solution with 90 to 98 mol mg end member it contains inclusions of coesite which has partially inverted to quartz resulting in a typical radial cracking of the host garnet around the inclusions several lines of evidence show that coesite crystallised under nearly static pressure conditions and that the whole matrix has once been coesite

collision orogen provenance western alps detrital signatures and unroofing trends abstract the alps are perhaps the best studied thrust belt formed during continent continent convergence collision orogen shallow intermediate and deep structural levels can be distinguished within the alpine thrust stack each shedding sediments with distinct petrographic and mineralogical signatures in modern first cycle sands carried by alpine rivers bulk composition rank of metamorphic lithic grains metamorphic index mi and dense mineral assemblages all faithfully mirror the tectono metamorphic history of exposed basement and cover units the shallow structural level widely preserved in the ligurian alps consists of remnant ocean turbidites shedding sedimentary to very low rank metasedimentary detritus documentclass aastex usepackage amsbsy usepackage amsfonts usepackage amssymb usepackage bm usepackage mathrsfs usepackage pifont usepackage stmaryrd usepackage textcomp usepackage portland xspace usepackage amsmath amsxtra usepackage ot2 ot1 fontenc newcomman

soil land use and landform relationship in the precambrian lowlands of northern ethiopia abstract soil landscape and vegetation pattern at a detailed scale 1 20 000 is non existent in the precambrian dominated lowlands 500 1500 m above sea level of northern ethiopia current studies at a detailed scale in the region have focused on the basalt and mesozoic rock limestone and sandstone dominated highland 2300 m above sea level areas the aim of this research was therefore to explain the soil distribution as a function of lithology land use and landform and to develop a methodology for up scaling to similar environments this study was conducted at aqushala watershed in the precambrian rock dominated avergelle lowlands the research was done based on a discrete model of spatial variation dmsv soil units identified 1 in the metamorphosed black limestone formation are vertic endoleptic calcisol humic at the upper slope plateau both vertic endoleptic cambisol calcaric humic and vertic leptosol calcaric humic at the middle slope hill hypercalcic calcisol at the foot slope and grumic vertisol calcaric humic at the lower slope valley bottom majority of the soil units were under cultivation 2 in the schist and slate formations are leptosol calcaric humic both at the upper slope and at the foot slope positions regosol calcaric over hypercalcic calcisol at the mid slope position and fluvisol calcaric humic at the valley bottom and 3 in the green reddish gray metamorphosed banded marl formation are leptic calcisol at the upper slope haplic calcisol at the foot slope and fluvisol calcaric humic at the valley bottom the model was tested in the taget control watershed and was 73 successful so if this model is used it can help a lot in every aspect of agricultural or natural resource management and planning processes

the evolution of the serie dei laghi strona ceneri and scisti dei laghi the upper component of the ivrea verbano crustal section southern alps north italy and ticino switzerland abstract the serie dei laghi is the upper intermediate component of the exposed crustal section of massiccio dei laghi in the southern alps the latter including also the ivrea verbano zone its oldest event is a sedimentary cycle at least of early paleozoic age it starts with a pelitic sequence scisti dei laghi that later suffered a tectono metamorphic event of rather high pressure this event is recorded by rare mineral and textural relics detected in the scisti dei laghi of the m gambarogno area later an arenaceous sequence strona ceneri was deposited it is now represented at the base by basaltic metatuffites resulting from the reworking of an ophiolite belt then followed by paragneisses with detrital phenoclasts ceneri gneiss and by fine grained gneisses gneiss minuti during the ordovician conspicuous tonalitic to granitic masses were emplaced the induced thermal disturbance and the circulation of pegmatitic stage magmatic residuals caused contact metamorphism and granitization in the sedimentary country rocks during the hercynian a main prograde event generated the regional foliation with isoclinal geometry and transposed character a syn kinematic stage produced medium grade parageneses of relatively high pressure static recrystallization and sillimanite growth then followed during the uplift due to the combined action of hydration and decompression margarite bearing coronitic textures grew around kyanite a retrograde metamorphism was then recorded by the appearance of greenschist facies parageneses at particular structural sites the formation of the cossato mergozzo brissago cmb and pogallo fault system against the ivrea verbano zone as well as the schlingen folds in the northeast is of late hercynian age along the cmb fault calc alkaline dykes and stocks appinites were intruded probably towards the end of the upheaval but deep enough to induce partial melting in their country rocks between val d ossola and valsesia the hercynian evolution is concluded by the early permian magmatic cycle that gave rise to both extrusive rhyolitic sheets and to granitic epiplutonic bodies accompanied by mafic dykes in mesozoic times the serie dei laghi was dissected by many extensional faults these partly reactivated the hercynian lineaments such as the cmb and pogallo lines during the alpine orogenic cycle the serie dei laghi was affected by s verging cataclastic overthrusts

the provenance of garnet constraints provided by studies of coastal sediments from southern india abstract the provenance of sediment with heavy mineral suites containing garnets with low grossular and high pyrope contents is enigmatic such garnet assemblages characterise sediments in many basins worldwide they are especially common in the sedimentary basins around northern britain but their source cannot be identified in adjacent basement rocks this paper documents garnet populations in beach dune and river sands from southern india which almost exclusively comprise low grossular high pyrope garnets these are derived from the high grade granulite facies metasedimentary and charnockitic rocks that form the basement in this area by analogy similar lithologies are inferred to source sediments with low grossular high pyrope garnet assemblages seen elsewhere in the case of the sandstones of northern britain the most likely location of such material is considered to be greenland

postglacial denudation of western tibetan plateau margin outpaced by long term exhumation the indus river one of asia s premier rivers drains the western tibetan plateau and the nanga parbat syntaxis these two areas juxtapose some of the lowest and highest topographic relief and commensurate denudation rates in the himalaya tibet orogen respectively yet the spatial pattern of denudation rates upstream of the syntaxis remains largely unclear as does the way in which major rivers drive headward incision into the tibetan plateau we report a new inventory of 10 be based basinwide denudation rates from 33 tributaries flanking the indus river along a 320 km reach across the western tibetan plateau margin we find that denudation rates of up to 110 mm k y 1 in the ladakh and zanskar ranges systematically decrease eastward to 10 mm k y 1 toward the tibetan plateau independent results from bulk petrographic and heavy mineral analyses support this denudation gradient assuming that incision along the indus exerts the base level control on tributary denudation rates our data show a systematic eastward decrease of landscape downwearing reaching its minimum on the tibetan plateau in contrast denudation rates increase rapidly 150 200 km downstream of a distinct knickpoint that marks the tibetan plateau margin in the indus river longitudinal profile we infer that any vigorous headward incision and any accompanying erosional waves into the interior of the plateau mostly concerned reaches well below this plateau margin moreover reported long term 10 6 yr exhumation rates from low temperature chronometry of 0 1 0 75 mm yr 1 consistently exceed our 10 be derived denudation rates with averaging time scales of 10 3 10 4 yr for our denudation data we report postglacial rates of downwearing in a tectonically idle landscape to counterbalance this apparent mismatch denudation rates must have been higher in the quaternary during glacial interglacial intervals

regional granulite facies metamorphism in the ivrea zone is the mafic complex the smoking gun or a red herring one widely accepted paradigm for the development of continental lower crust is that regional granulite facies metamorphism is caused by intrusion of mafic magma beneath or into the crust magmatic accretion the amphibolite to granulite facies supracrustal section exposed in the ivrea zone southern alps northern italy is commonly cited as a classic example establishing this postulated genetic relationship our interpretation of the pattern of metamorphic isograds compositional trends in high grade metasedimentary rocks and textural evidence in metapelite however indicates that final emplacement of the mafic plutonic rocks the mafic complex occurred subsequent to the regional thermal maximum field and petrographic relations suggest that a spatially restricted contact melting event in crustal rocks accompanied the emplacement of the mafic complex this inference is consistent with leucosome compositions in migmatites and a low pressure high temperature metamorphic overprint recorded by mineral assemblages in wall rocks proximal to the intrusion therefore evidence of anatexis and metamorphism of crustal rocks associated unequivocally with emplacement of the mafic complex is found only within an 2 km wide contact aureole overlying the intrusion the narrow aureole associated with emplacement of the mafic complex demonstrates that in some cases emplacement of large volumes of mafic magma within the crust does not inexorably lead to regional scale granulite facies metamorphism and large ion lithophile element depletion by melt loss

focused erosion at the core of the greater caucasus sediment generation and dispersal from mt elbrus to the caspian sea abstract the highest peaks in europe are found in the central greater caucasus an orogenic belt characterized by extremely active tectonic and sedimentary processes in this rugged mountain region we have investigated sand generation and erosion patterns by using high resolution petrographic and heavy mineral data on river sands complemented by detailed morphometric analysis of 9 major mountain branches of the terek river also presented is an extensive review of sediment transport data available in the russian literature on glacial lake outburst floods and rainfall triggered debris flows which owing to global warming and glacier retreat have afflicted the greater caucasus with increasing frequency in the last 50 years the accurate definition of mineralogical signatures characterizing detritus derived from six end member volcanic metamorphic basement and sedimentary metasedimentary rock units allowed us to calculate the relative contribution of each to the sand load with particular precision for the baksan river draining mt elbrus results clearly indicate that volcanic and basement rocks supply a disproportionate amount of sand relatively to their outcrop area testifying to strongly focused erosion in the high relief axial part of the range river channels here display extreme steepness ksn up to 200 300 and low concavity indices 0 15 0 35 typical of thalwegs shaped by debris flows average erosion rates reach as high as 2 4 mm a which is explained by the frequency of catastrophic mass transport events able to mobilize in one single episode between 106 and 107 tons of detritus corresponding to 10 50 mm of erosion distributed across the catchment upstream on 20 september 2002 the kolka glacier disaster mobilized 2 108 tons of debris corresponding to 400 mm of erosion in the upper genaldon valley to quantify the intrinsic capacity of different bedrock types to generate sand isolated from such a strong focused erosion effect we used the normalized steepness index ksn as a proxy of erosion rate and thus redefined the sand generation index as s g i s a s a a a k s n k s n a more realistic values are thus obtained although far more comprehensive data on sediment load than those presently available are required to discriminate robustly between the effect of focused erosion versus lithological control on sand generation

using detrital garnet compositions to determine provenance a new compositional database and procedure detrital garnet compositions can be used to help determine the provenance of sedimentary rocks in this study a garnet compositional database consisting of more than 2500 wet chemical and electron microprobe analyses was compiled from the literature for the garnets in the database the six principal garnet end member compositions pyrope almandine spessartine uvarovite grossular and andradite were calculated a multi stage methodology was devised to match garnet compositions to source rocks and a series of garnet provenance fields on ternary plots were identified the method was tested using compositional data from detrital garnet studies in several areas where provenance has already been identified with good results the methodology was then used to assess the provenance of detrital garnets from neogene sandstones of northern sabah borneo for which provenance is unknown and in a region where there are few garnet analyses for comparison comparison of garnet compositions from possible sources on palawan philippines and in borneo combined with the ternary plots excludes some known garnet bearing rocks as potential sources and suggests derivation of metamorphic and igneous garnets from palawan during the early miocene

geometry of eclogite facies structural features implications for production and exhumation of ultrahigh pressure and high pressure rocks western gneiss region norway 1 well preserved eclogite facies structural features in metamorphosed gabbro and diorite gneiss in baltica crust formed at a minimum depth of 60 70 km during the scandian orogeny allow direct inferences to be made regarding the geometry of folds kinematics and original structural orientations related to production and exhumation of high pressure rocks folds associated with eclogite facies fabrics are isoclinal to tubular with axes parallel to the trend of a stretching lineation strain estimates and l s or l s fabrics indicate that these structures were formed in a constrictional strain field locally they are well preserved in eclogite facies mylonite zones at least 40 m thick that cut proterozoic gabbro and adjacent gneiss where steeply dipping they show a north side up shear sense across a younger northeast trending shallowly plunging amphibolite facies anticlinorium formed in a constrictional noncoaxial strain field where original structural facing direction can be inferred small circle rotation of the eclogite facies lineation about the anticline axis indicates that the relative motion vector of baltica with respect to overlying imbricated crust and laurentia was oriented 320 in a present day reference frame this result is identical to the orientation of the relative motion vector estimated from paleomagnetic plate reconstructions and consistent with late silurian to early devonian oblique sinistral convergence between baltica and laurentia results of this study indicate that coherent baltica crust at 60 70 km depth experienced subvertical and horizontal shortening while extending toward the foreland during tops southeast thrusting parallel to plate motion high pressure rocks were progressively imbricated and stacked along eclogite facies mylonite zones with the deforming zone separating coherent baltica crust from imbricated basement above the constrictional strains under eclogite facies conditions are interpreted to have resulted from stretching associated with sinking of the cool dense mantle lithosphere

helium 3 emission from nevado del ruiz volcano colombia high helium 3 helium 4 ratios up to 6 6ratm 6 6 times the atmospheric ratio of 1 40 10 6 were observed in nine samples of gases and hot waters from seven sites located around the volcano nevado del ruiz colombia the values of the ratio decrease with distance from the crater such a tendency coincides well with the pattern first reported from the volcano ontake central japan and suggests a general signature of helium isotope ratios around individual volcanoes the corrected helium 3 helium 4 ratios at one gas vent sampled twice over six months increased this is interpreted to mean that the mantle contribution of helium may have increased with time

large scale folding in the upper part of the ivrea verbano zone nw italy new geological mapping has led to a new interpretation of the large scale superimposed folding in the upper part of the ivrea verbano zone italian alps the region is widely held to represent an upended section through lower continental crust of northern italy the dominant fold structure extending some 40 km along strike is the massone tight to isoclinal antiform with a hinge line strongly curved through 115 this folds pre existing large scale folds that formed during regional migmatization probably during the hercynian orogeny to form a type 2 interference geometry the region then suffered post orogenic mafic magmatic underplating and other magmatism accompanied by crustal stretching with contact metamorphism and migmatization causing the imposition of the final pattern of metamorphic isograds the ivrea verbano zone was brought into contact with the overlying metamorphic rocks of the serie dei laghi on a major shear zone sub solidus stretching continued though displacements on low angle high temperature shear zones most of the ivrea verbano zone was finally tilted to the vertical and emplaced into its present position after the mesozoic era and probably during alpine orogenesis forming the vertical limb of a crustal scale double kink

provenance evolution during arc continent collision sedimentary petrography of miocene to pleistocene sediments in the western foreland basin of taiwan taiwan is an example of an orogen involving a doubly vergent critical wedge critical wedge theory predicts asymmetrical tectonic development of the pro and retro sides of an orogen whereas the consequences for exhumation peak metamorphism and erosion have been extensively investigated the implications for sandstone petrography preserved on either side of an orogen have not been adequately documented plio pleistocene sandstones from the western foothills of taiwan were deposited in a rapidly subsiding foreland basin recording the collision between a volcanic arc and the asian passive margin new data on the evolution of sedimentary petrography and clay minerals preserved in miocene to pleistocene sandstone of the western pro foreland basin record the history of taiwan s orogenesis sandstone petrography of the eastern basin on the retro side of taiwan s orogenic wedge had been studied previously comparison of the provenance record from the western and eastern basins illustrates the opposing signature of unroofing and recycling held to be characteristic of an asymmetric orogenic wedge sandstone petrography can be used in ancient sedimentary basins to complement other indications of the polarity of subduction

garnet compositions in scottish and norwegian basement terrains a framework for interpretation of north sea sandstone provenance detrital garnets have proved to be useful discriminators of north sea sandstone provenance because they show a wide range of potential compositions and are relatively stable during burial diagenesis it has been less easy to use garnet data to provide a direct link between sediment and source because of the lack of a comprehensive database of garnet compositions in basement terrains forming the north sea hinterland this paper presents garnet compositional data from river sediments sourced from northern scotland and norway and demonstrates the presence of marked variations in garnet compositions from different regions related to fundamental differences in basement lithology the value of the river sediment database is demonstrated by comparing it with garnet compositions in paleocene sandstones from the north sea and more basins enabling the establishment of direct links between source and sediment paleocene sandstones in the gannet field area on the southwestern margin of the central north sea were derived from the dalradian of the grampian highlands those in the northern north sea were derived from the moine dalradian rocks of shetland and those along the more basin margin were derived from western norway by contrast paleocene sandstones in the nelson field central north sea and in the beryl embayment northern north sea have a garnet component that cannot be readily traced back to any basement terrain in either scotland or norway this component which was ultimately derived from granulite facies metasediments or charnockites is interpreted as being recycled from triassic sandstones which were themselves derived from an exotic source probably to the west of the british isles q 2004 elsevier ltd all rights reserved

scale linkage and contingency effects of field scale and hillslope scale controls of long term soil erosion anthropogeomorphic sediment flux in agricultural loess watersheds of southern germany abstract agricultural landscapes with a millennial scale history of cultivation are common in many loess areas of central europe over time patterns of erosion and sedimentation have been continually modified via the variable imposition of anthropogenic discontinuities and linkages on fragmented hillslope sediment cascades which eventually caused the complicated soilscape pattern these field records challenge topographically oriented models of hillslope erosion and simple predictions of longer term change of spatial soilscape by cultivation activities a thorough understanding how soilscape patterns form in the long term however is essential to develop spatial concepts of the sediment budget particularly for the spatial modeling of anthropogenic hillslope sediment flux using gis in this study i used extensive datasets of anthropogenic soil truncation and burial in a typical undulating loess watershed in southern germany 10 km2 wetterau basin n of frankfurt a m spatial soilscape properties and historic sediment flux as caused by cultivation over seven millennia were evaluated by these data the soilscape pattern on the low gradient hillslopes of the study area was found to be marked by a statistical near random pattern of varying depth thickness of truncation and overthickened burial moreover it was shown that truncation and burial had developed independently from each other and did not correlate with either hillslope gradient or downslope curvature hence in the field any combination of few nearly preserved severely truncated or completely removed soil profiles with either no some or a thick sediment cover is present thereby lacking an obvious spatial pattern here i suggest putting long term change of the soilscape into a contextual anthropogeomorphic systems perspective that accommodates components of human induced soil erosion operating at different spatial scales to interpret the longer term spatial consequences at the hillslope system level in the study area system scale linkages are marked by the spatial intersection of a finer scaled managed field system with a broader hillslope scale framework of natural erosion controls in the low gradient study area field borders exert control over the spatial reference of soil erosion and sedimentation sites over time this brought about a growing historical and spatial contingency change to the soilscape because of arbitrary spatial changes of the field system which are inherent in its socio agricultural maintenance thus the very low gradient and low erosivity setting of the study area have singled out the agency of human induced spatial and connectivity controls and contingency for long term spatial hillslope sediment flux although these findings may be less true for different settings they allow for deriving a generic conceptual model of the linkages between natural and anthropogenic subsystems to interpret the effects of long term human induced sediment flux accordingly the resulting balance between on hillslope net storage and net delivery to streams is scaling with basic physiographic properties of erosivity and sedimentation as well as the degree of anthropogenic hillslope fragmentation for loess areas in europe variable fields are fundamental anthropogeomorphic units that determine appropriate system scaling for historic sediment flux analysis and constrain retrodiction and prediction of changing fluxes at a point and a time at watershed scales methodical implications address adequate sampling strategies to record soilscape change as a result of which a critical review of the applicability of the catena concept to long cultivated hillslopes in central europe was included finally the suggested refined generic model of long term human controlled sediment flux involves a number of research opportunities particularly for linking modeling approaches to long term field records of cultivation related change in the soilscape

ultra long distance littoral transport of orange sand and provenance of the skeleton coast erg namibia abstract quantitative provenance analysis based on high resolution bulk petrography and heavy mineral data on beach and dune sands integrated with detrital zircon geochronology and chemical analyses of pyroxene garnet and staurolite demonstrates that sand derived from the orange river is carried by powerful and persistent longshore currents as far as northern namibia and southern angola 1750 km north of its mouth this is the longest cell of littoral sand transport documented so far compositional forward modeling indicates that 80 of dune sand in the skeleton coast is orange derived the remaining 20 being supplied by slow erosion of the damara orogen chiefly via the swakop river a decrease in basaltic rock fragments and pyroxene with relative enrichment in garnet staurolite tourmaline and other metamorphic minerals north of walvis bay indicates that only one third of beach sand in the 350 km dune free gap between the namib and skeleton coast ergs is orange derived the remaining two thirds being supplied largely by the swakop river draining the damara orogen although volcanic gravel becomes dominant in beaches of the skeleton coast north of the uniab mouth detritus from cretaceous etendeka lavas accounts for only 4 of beach sand reflecting limited sand generation in the arid catchment contributions from the kunene river to either dune or beach sands is ruled out indicating that gem diamonds found in placer deposits along the coast of namibia are all derived from the orange river

the oligocene alps domal unroofing and drainage development during early orogenic growth abstract the source of huge volumes of quartzofeldspathic detritus feeding oligo miocene foredeep turbidites of the apennines has long remained an unsolved geological enigma in this article we reinterpret the available sandstone petrography fission track stratigraphic and geomorphological evidence to demonstrate that the adriatic foredeep was dominantly sourced by a himalayan type tectonic aneurysm growing in the central alps since the late oligocene the lepontine dome the lepontine dome is the envelope of distinct subdomes that formed stepwise from east to west during northwestward indentation of adria beneath the axial alps focused erosion of domal culminations cut by antecedent drainage started suddenly in the late oligocene with unroofing of recently emplaced plutons and young amphibolite facies gneisses exhumation was tectonically driven and possibly accelerated by positive feedback between erosion and uplift of hot weak rocks from depth the huge volumes of resulting detritus gonfolite macigno clastic wedge were transported southward for hundreds of kilometers along the rapidly subsiding foredeep formed since middle eocene times in front of the alpine retrobelt and nascent apennine forebelt such massive sediment influx following 15 2 myr of starved foredeep sedimentation testifies to rapid formation of mountain relief in the central alps synchronous to dextral activity along the insubric fault the lepontine dome remains today as the only deeply dissected region in the alps where medium grade metamorphic rocks of the axial belt are extensively exposed the relationships between geological structures and drainage patterns still mirror those formed originally at oligocene times river headwaters have not been significantly displaced since then and their thalwegs constrain finite lateral displacement relative to the southalpine retrowedge to a maximum of 10 20 km our reconstruction has wide implications not only for a better understanding of the tertiary evolution of the alps apennines orogenic couple but also for general relationships among tectonic activity relief formation drainage development erosion distribution and long distance sediment transfer during continental collision and orogenic growth

divergence in subduction zones and exhumation of high pressure rocks eocene western alps abstract exhumation of high pressure rocks has long remained a controversial issue in the earth sciences in this article we analyze the tectono metamorphic stratigraphic and plate motion constraints from the western alps region providing new insights on exhumation mechanisms and tectonic evolution during the earliest orogenic stages eocene eclogites of the western alps form a 20 25 km wide belt on the upper plate side of the orogen eclogite belt exposed beneath extensional shear zones at the rear of a lower pressure accretionary wedge units of the eclogite belt show the youngest peak pressure assemblages within the subduction zone and experienced superfast tectonic exhumation since 45 40 ma the role of erosion was negligible during the whole of this stage eocene foreland basins remained starved and the massive arrival of axial belt detritus began well after exhumation was completed tectonic reconstructions based on fixed boundaries exhumation models e g channel flow and or implying fast erosion at the surface e g slab breakoff are thus not consistent with geological evidence in the lack of erosion exhumation through the overburden requires divergence within the subduction zone we demonstrate that this was not attained by rollback of the lower plate europe but was instead attained by nneward motion of the upper plate adria africa away from the western alps trench such motion induced localized extension within the weak portion of the upper plate at the rear of the accretionary wedge and allowed tectonic emplacement of the eclogite belt in the upper crust at rates much faster than subduction rates tectonic exhumation ceased in the oligocene when oblique divergence along the western alps traverse changed into oblique convergence the onset of slow erosional unroofing was synchronously recorded by pressure temperature paths in all major tectonic units of the western alps and by arrival of orogenic detritus in sedimentary basins this work demonstrates that divergence between upper plate and trench is a viable mechanism to exhume large and coherent eclogite units in continental subduction zones our exhumation model can be applied to other eclogite belts showing a similar exhumational record including the western gneiss region the dabie sulu and eastern papua new guinea

effects of land use and climate change on erosion intensity and sediment geochemistry at lake lehmilampi finland this paper aims to evaluate the possible relationships between erosion intensity and changes in climate and land use during the past 5 5 cal k years at lake lehmilampi eastern finland in this st

the continental crust as a source of sand southern alps cross section northern italy abstract all tectonostratigraphic levels of the continental crust from carbonate platforms in the dolomites to granulites in the ivrea zone are exposed along strike in the world famous southern alps cross section in this extraordinary natural laboratory we studied the composition of modern stream sands shed by each distinct type of source rock in order to improve on existing models of sediment provenance and specifically to reconstruct the step by step changes of detrital signatures ideally produced during unroofing of a continental block detritus from progressively deeper crustal levels of the southern alps changes systematically from lithic sedimentaclastic unmetamorphosed cover sequences to lithoquartzose quartzolithic and quartzofeldspathic metamorphiclastic greenschist facies to amphibolite facies basement units and finally to feldspathoquartzose and feldspathic composition granulite facies basement units six progressively richer types of heavy mineral assemblages ztr brookite garnet

tracking sediment provenance and erosional evolution of the western greater caucasus this article investigates landscape characteristics and sediment composition in the western greater caucasus by using multiple methods at different timescales our ultimate goal is to compare short term versus long term trends in erosional processes and to reconstruct spatio temporal changes in sediment fluxes as controlled by partitioning of crustal shortening and rock uplift in the orogenic belt areas of active recent uplift are assessed by quantitative geomorphological techniques digital elevation model dem analysis of stream profiles and their deviation from equilibrium and compared with regions of rapid exhumation over longer time intervals as previously determined by fission track and cosmogenic nuclide analyses complementary information from petrographic and heavy mineral analyses of modern sands and ancient sandstones is used to evaluate erosion integrated throughout the history of the orogen river catchments displaying the highest relief as shown by channel steepness indices correspond with the areas of most rapid exhumation as outlined by thermochronological data the region of high stream gradients is spatially associated with the highest topography around mount elbrus where sedimentary cover strata have long been completely eroded and river sediments display the highest metamorphic indices and generally high heavy mineral concentrations this study reinforces the suggestion that the bedrock channel network can reveal much of the evolution of tectonically active landscapes and implies that the controls on channel gradient ultimately dictate the topography and the relief along the greater caucasus our integrated datasets obtained during a decade of continuing research display a general agreement and regularity of erosion patterns through time and consistently indicate westward decreasing rates of erosional unroofing from the central part of the range to the black sea 2014 john wiley sons ltd

introduction to the special issue actualistic models of sediment generation conceptual models in sedimentary petrology that relate verticaland lateral compositional signatures during the lling of sedimentarybasins to their internal and external control factors have beendeveloped in the 80 ies and 90 ies of the last century althoughre ned petrographic and geochemical analyses have focussed ondeciphering complex events in time and space such as tectonic evo lution of source terranes changes in sediment dispersal patterns orpalaeoclimate uctuations quantitativemodelsarestillintheirinfancy despite a long history of research one reason for this state of affairs isthe strong interdisciplinary nature of the subject matter another isthe lack of appropriate modelling tools capable of dealing with thecomplex nature of sediment properties the recent proliferation ofquantitative data acquisition techniques coupled with progress indata processing and modelling approaches has led to the emergenceof a new eld of study aimed at solving the fundamental problem ofreconstructing mass transfer from source areas to sedimentary basins the term sediment generation acts as a convenient umbrella for thecomplex web of processes acting between source and sink quantitative models of sediment generation aim at providing anassessment of the type amount and rateof supplyof detritalmaterialfrom identi able parent rock assemblages to a basin ll in order toful l this objective two key questions must be addressed i how much sediment is being delivered ii what are the compositional and textural characteristics of thesediment the rst question is intimately connected to sediment budget as sessments and their derivative with respect to time i e erosion ordenudation and sedimentation rates the second one refers to the

truncation and accretion of soil profiles on coastal plain croplands implications for sediment redistribution soil stratigraphy and morphology in a small agricultural watershed on the coastal plain at clayroot north carolina indicate long term decadal scale patterns of the redistribution of sediment the most dramatic truncation of the soil profile occurs on convex upper slopes and suggests tillage and aeolian erosion as the major processes of soil loss thicker soils immediately downslope from convexities are consistent with redistribution by tillage but significant aeolian soil loss also occurs from some fields thinner apparently truncated soils were also associated with relatively steeper lower slope areas where contemporary rilling was observed the presence of thicker cumulic soils at toeslopes where small fans are observed at rill termini and about a half meter of alluvium in drainage ditches indicates that water erosion is also quite prominent distinctive soil stratigraphy is found in areas of aeolian deposition where podzolization in sandy surface deposits has created compound soil profiles on convex slopes tillage and wind erosion result in net soil loss with the former dominating on wetter soils and when plowing occurs and aeolian processes dominating on drier hilltops and when no till or minimum tillage practices are followed soils are thicker immediately downslope from convexities with thinner soils and rill erosion on lower slopes thickened soils and colluvial deposition in the form of thin fan deposits occur at toeslopes and in depressions the borders of fields often have thicker soils because of aeolian deposition water wind and tillage processes are all significant in soil redistribution at the clayroot site with relative importance in space and time controlled by topography soil properties seasonal moisture and vegetative cover and tillage practices

detrital fingerprints of fossil continental subduction zones axial belt provenance european alps abstract collision orogens such as the alps or the himalayas are generated by plate convergence culminating in attempted subduction of a thinned continental margin massive amounts of metamorphic rocks displaying high pressure parageneses are produced during such relatively brief tectonic events and then rapidly exhumed to form the axial backbone of the new orogen sediment composition provides a fundamental key to identify past events of continental subduction although coupled detrital geochronology techniques are needed to discriminate neometamorphic and paleometamorphic sources of detritus within the austroalpine cretaceous and penninic eocene axial belts of the alps we ideally distinguish three structural levels each characterized by diagnostic detrital fingerprints the shallow level chiefly consists of offscraped remnant ocean turbidites and unmetamorphosed continental margin sediments and mostly produces lithic to quartzolithic sedimentaclastic sands yielding very poor heavy mineral suites inc

magmatic underplating extension and crustal reequilibration insights from a cross section through the ivrea zone and strona ceneri zone northern italy the thermal impact of magmatic underplating at various crustal levels is studied along a traverse through the ivrea verbano zone and strona ceneri zone in northern italy geochronological and petrologic data are compared to a two dimensional thermal kinematic model field data and numerical simulation show the strong disturbance of the temperature field in the lower and intermediate crust in relation to magmatic underplating leading to granulite to amphibolite facies metamorphism as well as reequilibration of mineral chemical and isotopic systems magmatic underplating leaves a crust with an apparently heterogeneous tectonometamorphic evolution as information on the earlier history is preserved only at upper crustal levels

provenance of heavy mineral deposits on the northwestern shelf of the south china sea evidence from single mineral chemistry abstract a study of heavy mineral geochemistry has been carried out in order to examine the potential sources of heavy mineral deposits within surficial sediment on the northwestern shelf of the south china sea tourmaline amphibole and garnet from six samples near the coast and eleven samples on the shelf were analyzed by an electron microprobe chemical varieties of tourmaline and amphibole indicate that the pearl river is the main supplier of sandy sediments on the eastern shelf within a 100 km radius west of the paleo deltas sandy sediments on the western shelf are mainly sourced from the jian river and the wanquan river heavy mineral placers on the middle and outer shelves are mainly derived from reworking of the paleo pearl river deltas heavy mineral placers in the west are mainly sourced from the small rivers and are distributed in the sandy deposits near the coasts this study demonstrates that the occurrence of heavy mineral placers on wide continental shelf is mainly determined by the sediment supply and marine processes during transgressions

soil development along an elevational transect in the western sierra nevada california soil development along an elevational transect on the western slopes of the the central sierra nevada was investigated to assess the effects of climate on soil properties and processes the transect of seven soils formed in granitic residuum spans elevations from 198 to 2865 m with mean annual temperature and precipitation differences of 13 c 3 9 16 7 and 94 cm 33 127 respectively soil ph decreased by about two units and base saturation decreased from 90 to 10 with increasing elevation concentrations of organic c in the solum increased with elevation with the largest single increase occurring between the oak woodland 5 6 kg c m2 and mixed conifer sites 10 15 kg c m2 clay mineralogy showed a general trend of desilication and hydroxy al interlayering of 2 1 layer silicates with increasing elevation the degree of chemical weathering based on clay and secondary fe oxide concentration in the solum showed a maximum clay 536 kg m2 and fe oxides 24 kg m2 at mid elevations having intermediate levels of precipitation and temperature while some soil properties show a continuous progression e g organic carbon base saturation clay mineralogy with elevation other properties e g ph soil color clay and secondary fe oxide concentrations show a pronounced change threshold type step over a short distance at about 1600 m the explanation for the abrupt nature of this shift is not known however it coincides with the approximate elevation of the present day average effective winter snow line

a classification of metamorphic grains in sands based on their composition and grade abstract an operational classification of metamorphic grains in sands and sandstones is proposed with the aim of enhancing data reproducibility among operators and the potential of high resolution bulk petrography in provenance studies for each of four protolith compositions metapelite metapsammite metafelsite metacarbonate metabasite six archetype grains displaying increasing degree of recrystallization and foliation development are illustrated such a classification grid is specifically devised as a subsidiary tool for point counting with the gazzi dickinson method traditional qfr parameters can also be easily recalculated from the data set obtained thus meeting all possible needs decker and helmold 1985 suttner and basu 1985 an experiment shows that usage of visual comparison standards effectively minimizes operator variation and allows retrieval of crucial information during point counting in a reproducible way a petrogenetic grid is presented as a subsidiary tool for classifying grains that include index minerals and to help correlation with dense mineral data the metamorphic index mi is introduced as an estimator of average metamorphic grade of source rocks our classification an extension of concepts used first in the study of arc continent collision in taiwan dorsey 1988 and successfully expanded to interpret the evolution of continent continent collision in the himalayas najman and garzanti 2000 white et al 2002 proves to be fruitful in provenance analysis of foreland basin sediments shed from alpine type thick skinned collision orogens particularly when integrated with dense mineral geochemical and geochronological data

petrogenesis and tectonic significance of amphibolites interlayered with metasedimentary gneisses in the ivrea zone southern alps northwest italy abstract amphibolites occurring as elongate lenses and boudins within the metasedimentary kinzigite formation of the ivrea zone are all of igneous parentage a detailed study of their trace element characteristics shows that they can be divided into two groups type 1 amphibolites occur as layers up to 100 m thick and have trace element distributions showing depletion in incompatible elements typical of normal n type mid ocean ridge basalts type 2 amphibolites occur as thinner layers and boudins and have higher levels of the more incompatible elements similar to transitional or enriched e type ocean basalts although metamorphism appears to have resulted in loss of sio 2 and variable enrichment in na k rb ba sr and locally ca the less mobile elements including the rare earth elements have preserved the primary basaltic geochemical characteristics the tectonic model which best explains the assemblage of slivers of morb like amphibolites within extremely highly deformed semi pelitic metasediments is that of an accretionary sedimentary wedge formed at a palaeozoic subduction zone

collision tectonics in the swiss alps insight from geodynamic modeling this paper compares results from two dimensional finite element dynamic modeling with the kinematic evolution of the swiss alps during the collision phase in particular we investigate the role of inherited lateral strength heterogeneities on orogenesis a number of first order characteristics are directly comparable at crustal scales in the models the entry of continental crust into the convergent margin marks the end of near perfect subduction accretion of material of the subducting plate to the upper plate creates an orogenic wedge on the incoming pro side and initiates a retroshear zone or model backthrust the addition of material to the upper plate builds a bivergent orogen heterogeneities in the pro crust focus shear and lead to the development of nappe structures the combined action of pro shear nappe stacking and retroshear backthrusting uplifts a plug between the two shear zones subsequent focusing of shear along the retroshear zone results in rotation of the plug and overlying units leading to crustal scale backfolds as observed in the swiss alps the model experiments predict features relevant to alpine dynamics including 1 similar crustal thicknesses and exhumation patterns to those observed in the swiss alps today for erosion rates comparable to natural ones 1 mm yr 1 2 continued accretion and subduction of upper crustal fragments allowing high pressure metamorphic conditions 3 tilting and exhumation of lower crust when a midcrustal weak zone is present and 4 shunting of material across the strong lower crustal wedge of the upper plate

new geochemical results indicate a non alpine provenance for the alpine spectrum epidote garnet hornblende in quaternary upper rhine sediment abstract the heavy mineral assemblage of late pleistocene to modern rhine river sediment in the upper rhine graben is dominated by garnet green amphibole and epidote this so called alpine spectrum has been taken to indicate an exclusive derivation from the alps and has hitherto been investigated with optical methods only we present the first single grain geochemical data set of garnet and amphibole from the upper rhine river and some of its main tributaries we use the new data to test the alleged alpine provenance in the rhine our results show that the provenance of garnet mostly pyrope rich almandine is grain size dependent particularly the pyrope content indicates that the 0 063 0 25 mm size fraction has an alpine provenance whereas 0 25 0 5 mm grains derived from the black forest and the vosges which flank the upper rhine graben they mainly comprise of paleozoic metamorphic and igneous rocks supplying a suite of heavy minerals similar to the alpine spectrum to the rhine river amphibole mostly mg hornblende has an increasing tio2 content from the south to the north of the graben which also indicates an input from the graben shoulders the new data indicate that the so called alpine spectrum of heavy minerals in rhine river sediment of the upper rhine derived to significant degrees from non alpine sources furthermore our results indicate a relatively uniform provenance for the rhine river system during the past 1 ma

the provenance of triassic continental sandstones from the beryl field northern north sea mineralogical geochemical and sedimentological constraints a geochemical study of the heavy mineral suite in triassic strata from two wells in the beryl embayment was undertaken in order to identify changes in provenance through the lewis formation detailed provenance studies also allow the reconstruction of paleodrainage patterns and aid in predicting facies distributions the heavy mineral assemblage in the lewis formation is dominated by almandine pyrope garnets which are typically derived from pelitic metasediments together with zircon apatite tourmaline and rutile some of which are rich in niobium nb these latter phases could have been sourced either from metasediments or granitic protoliths although nb rich rutiles have a more restricted paragenesis being associated with alkaline plutonic rocks and granite pegmatites in the uppermost members of the lewis formation influxes of more exotic provenance specific heavy minerals such as cr spinel staurolite and chloritoid become more common the chemistry of the detrital cr spinel implies that it was derived from an ophiolitic source gross grain size and facies changes in the embayment suggest a nw to se dispersal of detritus although hydraulic sorting of the heavy mineral suite between relatively distal and proximal locations has resulted in subtle variations in whole rock trace element geochemical signatures the complete overlap in the geochemical data from distal and proximal wells requires that the sediments were essentially derived from a single source area the combination of mineralogical sedimentological and geochemical data implies that the dominant source for these sediments was the devonian old red sandstone ors the shetland ophiolite and the underlying dalradian metasedimentary rocks of the shetland isles and the east shetland platform provenance studies such as this are central to the reconstruction of paleo drainage patterns which in turn lead to improved prediction of potential reservoir quality distribution and connectivity

soil landscape relationships in the basalt dominated highlands of tigray ethiopia article i nfo though knowledge about the distribution and properties of soils is a key issue to support sustainable land management existing knowledge of the soils in tigray northern ethiopian highlands is limited to either maps with a small scale or with a small scope the goal of this study is to establish a model that explains the spatial soil variability found in the may leiba catchment and to open the scope for extrapolating this information to the surrounding basalt dominated uplands a semi detailed scale 1 40000 soil survey was conducted in the catchment profile pits were described and subjected to physico chemical analysis and augerings were conducted this information was combined with information from aerial photographs and geological and geomorphologic observations the main driving factors that define the variability in soil types found were 1 geology through soil parent material and the occurrence of harder layers often acting as aquitards or aquicludes 2 different types of mass movements that occupy large areas of the catchment and 3 severe human induced soil erosion and deposition these factors lead to red black skeletic cambisol pellic vertisol catenas on basalt and calcaric regosol colluvic calcaric cambisols calcaric vertisol catenas on limestone the driving factors can be derived from aerial photographs this creates the possibility to extrapolate information and predict the soil distribution in nearby regions with a comparable geology a model was elaborated which enables the user to predict soil types using topography geomorphology geology and soil colours all of which can be derived from aerial photographs this derived model was later applied to other catchments and validated in the field

the alps in the cretaceous a doubly vergent pre collisional orogen current palaeotectonic models see the alps chiefly as a collisional orogen with the southalpine retrobelt developed only as a post collisional feature new structural and geochronological data show instead that the continental margin of africa adria was being structured as a doubly vergent orogen during subduction of alpine tethys in the cretaceous tens of million years before collision with europe subduction is envisaged here to have nucleated in the latest albian cenomanian within the attenuated adriatic margin most continental slivers exhumed as eclogites in the axial part of the cretaceous orogen contain gabbros and relics of ht lp metamorphic rocks indicating inheritance from permian to jurassic rifting cretaceous shortening in the southalpine retrobelt is indicated by several lines of evidence including orogen derived turbidites and syn sedimentary compressional activity since the cenomanian upper cretaceous pseudotachylytes dating major s severging thick skinned thrusts and widespread fold and thrust deformation cut by eocene plutons and dikes

a multivariate discrimination scheme of detrital garnet chemistry for use in sedimentary provenance analysis abstract garnet chemistry provides a well established tool in the discrimination and interpretation of sediment provenance current discrimination approaches however i suffer from using less variables than available ii subjective determination of discrimination fields with strict boundaries suggesting clear separations where in fact probabilities are converging and iii significant overlap of compositional fields of garnet from different host rock groups the new multivariate discrimination scheme is based on a large database a hierarchical discrimination approach involving three steps linear discriminant analysis at each step and the five major host rock groups to be discriminated eclogite a amphibolite b and granulite c facies metamorphic rocks as well as ultramafic d and igneous rocks e the successful application of statistical discrimination approaches requires consideration of the a priori knowledge of the respective geologic setting this is accounted for by the use of prior probabilities three sets of prior probabilities priors are introduced and their advantages and disadvantages are discussed the user is free to choose among these priors which can be further modified according to the specific geologic problem and the level of a priori knowledge the discrimination results are provided as integrated probabilities of belonging to the five major host rock groups for performing calculations and results a supplementary excel spreadsheet is provided the discrimination scheme has been tested for a large variety of examples of crystalline rocks covering all of the five major groups and several subgroups from various geologic settings in most cases garnets are assigned correctly to the respective group exceptions typically reflect the peculiarities of the regional geologic situation evaluation of detrital garnets from modern and ancient sedimentary settings of the western gneiss region norway eastern alps austria and albertine rift uganda demonstrates the power to reflect the respective geologic situations and corroborates previous results as most garnet is derived from metamorphic rocks and many provenance studies aim at reconstructing the tectonic and geodynamic evolution in the source area the approach and the examples emphasize discrimination of metamorphic facies i e temperature pressure conditions rather than protolith composition

provenance of tertiary volcanoclastic sediment in nw thrace bulgaria evidence from detrital amphibole and pyroxene geochemistry abstract detrital heavy mineral and bulk rock geochemistry and a review of sandstone petrographic data have been used to investigate the post collisional effusive magmatism that followed the closure of the vardar ocean and the generation of volcanic sediments in a complex and compositionally variable volcanic region available petrographic data gives evidence of contributions from three key source areas corresponding to the three main tectonic units the structurally lower gneiss migmatite complex byala reka kechros and kesebir kardamos domes and the upper variegated kimi complex both fringed by the low to medium grade mesozoic rocks of the circum rhodope belt besides the deposition of siliciclastic material volcanic contributions from both intermediate and acid products represent an important source of sediment in the area despite dominant intermediate to acid volcanic products volcanic lithic fragments in sandstones microlithic lathwork and brown vitric textures indicate main inputs from intermediate and basic intermediate products generating questions on the interpretation of volcanic detritus in reconstruction of provenance detrital amphibole and pyroxene chemistry is used to characterise the supply of volcanic material as well as the dispersal mechanisms and understand the role played by each of the volcanic centers present in the area in the infill of the north western thrace basin amphibole chemistry reveals high compositional heterogeneity according to both compositional variability of the numerous volcanic centres active at the time of deposition and presence of metamorphic amphibole 4 al and al t apfu values indicate that most of the amphiboles from the nerz are not of volcanic origin and their presence can only be attributed to the numerous amphibolite facies metamorphic rocks abundantly documented in the area detrital amphibole compositions from the zkvs indicate major contributions from the iran tepe and zvedzel volcanoes analysed detrital clinopyroxenes from the nerz are mostly diopside augite with no hedenbergite or fe augite detected the 4 al 6 al ratio is comparable with compositions of volcanic pyroxenes from the momchilgrad arda zkvs region and products from the pre caldera phase of the borovitza

reconstructing the exhumation history of the lesser himalaya nw india from a multitechnique provenance study of the foreland basin siwalik group 1 this research presents the first multitechnique provenance study of the siwalik group in the himalayan foreland basin in india using the jawalamukhi section magnetostratigraphically dated at 13 5 ma combined with provenance data from a dharamsala formation sedimentary section 21 13 ma located close by it forms the longest temporally continuous record of himalayan erosion in the indian foreland basin sandstone petrography and heavy mineral analysis conglomerate clast composition ar ar dating of detrital white micas and sm nd analyses on siltstones conglomerate matrix and conglomerate clasts was undertaken to determine 1 shifts in source region through time and 2 changes in detrital lag times related to exhumation rates in the hinterland together interpreted in the light of thrusting events we interpret the data to show a slow down in exhumation rate of the higher himalaya by 16 17 ma after which time the locus of thrusting propagated south of the main central thrust and erosion of the low grade haimanta formation to the south became significant the nonmetamorphosed inner lesser himalaya breached its haimanta cover by 9 ma with the metamorphosed inner lesser himalaya lesser himalayan crystalline series exhuming to surface by 6 ma this event caused sufficient disruption to established drainage patterns that all higher himalayan material was diverted from this location at this time

the potential of detrital garnet as a provenance proxy in the central swiss alps abstract detrital garnet is a promising candidate to reliably fingerprint sediment sources in the alps which has so far been complicated by the wide range and similarity of some of the lithologies garnet is present in most alpine sediments is easy to identify is fairly stable and most importantly reflects the type and the metamorphic grade of its source rock in its chemical composition this study aims to establish fingerprints based on detrital garnet composition for the most important tectonic units of the central alps including european penninic and adriatic basement rocks and their respective metasedimentary covers sediments collected from modern rivers which drain representative portions of the individual tectonic units contain a natural mixture of the various garnet populations present in each unit we selected six catchments in southwestern switzerland draining the external massifs helvetic sediments and the penninic nappe stack at the transition of alpine greenschist to amphibolite facies metamorphism in order to test the variability of alpine garnets and the role of inherited pre alpine garnets extraordinary grossular and spessartine rich garnets of the external massifs which experienced greenschist facies metamorphism are clearly distinguishable from generally almandine rich garnets supplied by the higher grade metamorphic penninic nappe stack the variable pyrope grossular and spessartine components of these almandine rich garnets can be used to further distinguish pre alpine alpine eclogite facies and low grade metasedimentary garnets this provenance proxy has the potential to be used for reconstructing sediment sources transport and dispersal patterns in a variety of settings throughout the alpine sedimentary record

the history of soil erosion and fluvial deposits in small catchments of central europe deciphering the long term interaction between humans and the environment a review abstract during the last few decades many case studies focused on the dynamics of fluvial systems in response to hillslope erosion land use impact and climate changes this paper will review the current state of knowledge of the dynamics of past soil erosion and gullying in small catchments

geothermobarometry p t paths and metamorphic field gradients of high pressure rocks from the adula nappe central alps metabasic rocks from the adula nappe in the central alps record a regional high pressure metamorphic event during the eocene and display a regional variation in high pressure mineral assemblages from barroisite or glaucophane bearing garnet amphibolites in the north to kyanite eclogites in the central part of the nappe high pressure rocks from all parts of the nappe show the same metamorphic evolution of assemblages consistent with prograde blueschist high pressure amphibolite or eclogite facies conditions followed by peak pressure eclogite facies conditions and decompression to the greenschist or amphibolite facies average pt calculations using thermocalc quantitatively establish nested clockwise p t paths for different parts of the adula nappe that are displaced to higher pressure and temperature from north to south metamorphic conditions at peak pressure increase from about 17 kbar 640 c in the north to 22 kbar 750 c in the centre and 25 kbar 750 c in the south the northern and central adula nappe behaved as a coherent tectonic unit at peak pressures and during decompression and thermobarometric results are interpreted in terms of a metamorphic field gradient of 9 6 2 0 c km 1 and 0 20 0 05 kbar km 1 these results constrain the peak pressure position and orientation of the nappe to a depth of 55 75 km dipping at an angle of approximately 45 towards the south results from the southern adula nappe are not consistent with the metamorphic field gradient determined for the northern and central parts which suggests that the southern adula nappe may have been separated from central and northern parts at peak pressure

single grain heavy mineral provenance of garnet and amphibole in the surveyor fan and precursor sediments on the gulf of alaska abyssal plain implications for climate tectonic interactions in the st elias orogen abstract the st elias orogen formed as a result of the northwestward drift of the yakutat terrane along and final collision with the alaska margin in the miocene its exhumation coincided with changing glacial conditions that are considered to have strongly interacted with mountain building processes a significant part of the record of these tectonic climatic interactions is stored in sediments on the gulf of alaska abyssal plain including the surveyor fan our study examines temporal provenance changes of miocene through pleistocene sediments of the surveyor fan gulf of alaska to constrain the dynamics of exhumation and mass transfer from the evolving st elias orogen to the adjacent surveyor deep sea fan we present single grain geochemical data of amphibole and garnet and 40 ar 39 ar cooling ages of biotite and amphibole together with point counting data of heavy minerals from sands and silts from two sites in the distal and proximal fan drilled by iodp expedition 341 in 2013 sites u1417 and u1418 respectively a shift in heavy mineral composition during the miocene predating the onset of glaciation points to a tectonically induced change in erosion centers and sediment transport probably caused by the rise of the st elias mountains garnet and amphibole data suggest the chugach metamorphic complex is the main sediment source implying input to the surveyor fan from sources relatively far in the north during the miocene changing provenance signals from the miocene to pliocene suggest rising input from the lower grade metamorphic areas at the southern flanks of the orogen indicating the advance of glaciers to the tidewater line providing material from this flanking region higher input from the chugach metamorphic complex in all pleistocene sediments suggests the northern hemisphere glaciation at the plio pleistocene boundary caused erosion and sediment yield from the interior of the orogen climatic changes at the mid pleistocene transition did not cause significant changes in the provenance signal

the cossato mergozzo brissago line and the pogallo line southern alps northern italy and their relationships with the late hercynian magmatic and metamorphic events abstract the hercynian basement of the southern alps west of lago di lugano consists of two units the ivrea verbano which is well known for its lower crust and upper mantle rocks and as the seat of a marked gravimetric positive anomaly and the serie dei laghi an intermediate to upper crustal metasedimentary and metagranitic complex the contact between them is a subvertical tectonic discontinuity the cossato mergozzo brissago line cmb and pogallo line recently the subject of considerable interest as the possible analogue of a low angle normal fault later tilted to the present upright position such as those increasingly revealed by the deep reflection seismics in thinned continental crust late hercynian igneous activity mainly took place along this lineament the contact is however very complex the cossato lower valsesia segment is poorly exposed and has been reactivated by a younger fault cremosina line in the valsesia val d ossola toce river segment the cmb line is expressed as a strong structural and lithological contrast as well as by a narrow belt of mylonites in the val cannobina lago maggiore sector the mylonites are distributed over a considerable thickness mostly within the serie dei laghi they are connected with large scale ductile folding on nearly vertical axes schlingenbau the cmb line is dissected by several orthogonal and oblique subvertical faults grottaccio quarna val lessa val pogallo faults the presence of appinitic calcalkaline dykes and stocks of about 285 ma intruded along particular segments of the cmb isolated by those faults suggests that the attitude of the main tectonic boundary was upright at the time of intrusion the intrusion apparently occurred in a transtensional environment and induced a temperature increase in the country rocks causing a low pressure metamorphic overprint in the val cannobina lago maggiore segment and dehydration melting in a belt 2 3 km wide between valsesia and val d ossola the pogallo line cuts across the cmb line with a sinistral horizontal slip of about 11 km and is also characterized by amphibolite facies mylonites the absence of mylonitic appinites and consistent geologic evidence point to formation of the fault before 285 ma a significant mesozoic displacement along both faults is therefore excluded even though post permian reactivations are demonstrated by the presence of rb sr and k ar mica mixed ages along the cmb line a new evolutionary model can be proposed to account for most of the geological petrological and geophysical data early paleozoic continental accretion subduction and magmatic arc followed by a more external probably oblique hercynian reactivation inducing important transcurrent movements along cmb and pogallo before the early permian magmatic phase

changes in detrital garnet assemblages related to transpressive uplifting associated with strike slip faulting an example from the cretaceous system in kii peninsula southwest japan abstract the chemical characteristics of detrital garnet have served as relatively reliable and definitive indicators of the major tectonic settings of sedimentary units in many parts of the world in southwest japan a multidisciplinary approach combining sandstone modal heavy mineral and garnet compositional analyses of the cretaceous upper continental slope to trench deposits of the kurosegawa and shimanto belts combined with a comparison of the detrital garnet features in and around kii peninsula revealed the following characteristics the garnet assemblages show significant changes with age the lower cretaceous yuasa formation is characterized by pyrope rich almandine garnets derived from granulite facies metamorphic rocks these are associated with garnet grains that have pyrope almandine compositions and high grossular contents suggesting an eclogite origin garnet assemblages of the lower upper cretaceous yukawa formation are dominated by grains with chemical characteristics indicating an origin as low p t type metamorphic rocks there are also spessartine almandine garnets derived from acidic igneous rocks some with a high p t type metamorphic origin and others with a grandite composition garnet assemblages of the upper upper cretaceous miyama formation are similar to those of the yukawa formation with the exception that grandite garnets are absent the above compositional changes of garnets in the deposits allow us to characterize the corresponding provenances and by combining these results with stratigraphic ages temporal changes of these provenances can also be determined the source area for the granulite facies metamorphic rocks that continuously supplied detritus throughout the cretaceous might be precambrian continental basement in east asia in early late cretaceous time the detritus was derived from terranes distributed along the median tectonic line a major strike slip fault stretching throughout southwest japan the garnet compositions suggest the source area included eclogite in the kurosegawa belt that forms the basement to the cretaceous strata and the low p t type metamorphic rocks and granitic rocks in the paleo ryoke belt including the higo belt studies of the miyama formation show that at this time widespread acidic volcanism began and this was the source for much of the volcanic sediment in the formation the provenance change between the lower and lower upper cretaceous formations is likely to have been caused by uplifting and unroofing associated with cretaceous transpression expressed by the strike slip movement along the median tectonic line and other lateral faults in the chichibu belt

the euphrates tigris karun river system provenance recycling and dispersal of quartz poor foreland basin sediments in arid climate we present a detailed sediment provenance study on the modern euphrates tigris karun fluvial system and mesopotamian foreland basin one of the cradles of humanity our rich petrographic and heavy mineral dataset integrated by sand geochemistry and u pb age spectra of detrital zircons highlights the several peculiarities of this large source to sink sediment routing system and widens the spectrum of compositions generally assumed as paradigmatic for orogenic settings comparison of classical static versus upgraded dynamic petrologic models enhances the power of provenance analysis and allows us to derive a more refined conceptual model of reference and to verify the limitations of the approach sand derived from the anatolia zagros orogen contains abundant lithic grains eroded from carbonates cherts mudrocks arc volcanics obducted ophiolites and ophiolitic melanges representing the exposed shallow structural level of the orogen with relative scarcity of quartz k feldspar and mica this quartz poor petrographic signature characterizing the undissected composite tectonic domain of the entire anatolia iranian plateau is markedly distinct from that of sand shed by more elevated and faster eroding collision orogens such as the himalaya arid climate in the region allows preservation of chemically unstable grains including carbonate rock fragments and locally even gypsum and reduces transport capacity of fluvial systems which dump most of their load in mesopotamian marshlands upstream of the arabian persian gulf allochemical carbonate factory quartz poor sediment from the anatolia zagros orogen mixes with quartz rich recycled sands from arabia along the western side of the foreland basin and is traced all along the gulf shores as far as the rub al khali sand sea up to 4000 km from euphrates headwaters

raman spectroscopy in heavy mineral studies abstract raman spectroscopy is an innovative tool with tremendous potential serving as a fun damental complement to a variety of provenance methods including heavy mineral analysis anddetrital geochronology because of its accuracy ef ciency and versatility the results of theraman technique are indispensable for fully reliable identi cation of heavy minerals in grainmounts or thin sections thorny long standing problems that cannot be solved con dently witha polarizing microscope alone such as the determination of opaque and altered heavy minerals of detrital grains as small as a few microns or of colourless crystals with uncertain orientationand rounded morphology can nally be addressed although the method can be highly automa tized the full ability and experience of the operator is required to combine raman data with theoptical information obtained under the microscope on the same grains which is essential for theef cient application of the method in provenance studies this article provides exemplaryramanspectrausefulforthecomparisonand determinationof over70 differentopaqueandtrans parent heavy mineral species commonly found in sediments conveying speci c information onthe genesis of their source rocks and thus is particularly useful in provenance diagnoses andpalaeotectonic reconstructions supplementary material detailed information on the lasers used and the origin of the analysedminerals is available at http www geolsoc org uk sup18615it is the scattering of light by atoms and moleculesthat gives us the light of the sky the blue colour ofthe deep sea and the delicate opalescence of largemasses of clear ice raman 1928 pp 368 369

evaluation of garnet discrimination diagrams using geochemical data of garnets derived from various host rocks abstract this work is an attempt to evaluate six different garnet discrimination diagrams one binary diagram and five ternary diagrams commonly used by many researchers the mineral chemistry of detrital garnet is a useful tool in sedimentary provenance studies yet there is no clear cut understanding of what garnet type originates from which host lithology several discrimination diagrams exist for garnet showing distinct compositional fields separated by strict boundaries that are thought to reflect specific types of source rocks for this study a large dataset was compiled n 3532 encompassing major element compositions of garnets derived from various host lithologies including metamorphic igneous and mantle derived rocks in order to test the applicability of the various discrimination schemes the dataset contains mineral chemical data collected from the literature complemented with some new data n 530 from garnet bearing metamorphic and ultramafic rocks in austria and norway discrimination of the tested diagrams only works for a small group of garnets derived from mantle rocks granulite facies metasedimentary rocks and felsic igneous rocks for other garnet types the assignment to a certain type of host rock remains ambiguous this is considered insufficient and therefore the evaluated diagrams should be used with great care we further apply compositional biplot analysis to derive some hints towards future perspectives in detrital garnet discrimination