characterization of granitoid and gneissic weathering profiles of the mucone river basin calabria southern italy the paper deals with the development of a multidisciplinary research on weathering profiles of granitoid and gneissic rocks related to tectonic and landscape evolution of the western sila grande massif calabria southern italy field scale observations and petrographical and mineralogical features are used to characterize in detail the weathering processes the weathering profiles of the granitoid cut slopes are generally simple showing a progressive weathering increase toward the top of the slopes whereas the weathering profiles of the gneissic cut slopes are generally complex with irregularities in the spatial distribution of weathered horizons the microfabric and petrographic analyses show that gneissic samples classes v vi of weathering grade are characterized by higher percentage of altered minerals and microfracture and void rather than granitoid samples classes v vi of weathering grade the main mineralogical changes concern the partial transformation of biotite and the partial destruction of feldspars mainly plagioclases associated with the neoformation of secondary minerals clay minerals and fe oxides and with a substitution of the original rock fabric neoformed clay minerals and ferruginous products replaced feldspars and biotite during the most advanced weathering stage referred as physical changes coupled with chemical variations the final results of weathering process are a soil like material characterized by sand gravel grain size fraction for the granitoid rocks and by both silt clay and sand silt grain size fraction for the gneissic rocks this generally produces a greater value of the sgi sand generation index for granitoids and explains the great productivity in sandy deposits of this lithology

weathering and morphogenesis in a mediterranean climate calabria italy abstract deeply weathered plutonic rocks occur widely in the sila massif calabria southern italy three representative weathering profiles developed on the hilltops indicate that sand represents more than 50 by weight throughout most of the weathering profile and silt and clay size fractions are also well represented filling the interstices among corestones both sand and finer fractions of grus and soil horizons are thought to be derived from a combination of granular disintegration and chemical decomposition developed on relatively flat terrains of the sila massif these slopes are now experiencing transport limited morphodynamics under a montane modified mediterranean climate the depth of the weathered layers that have suffered little erosional truncation typically exceed 15 m and may reach 50 60 m or more major isolated or grouped exfoliation boulders are the most common minor landform feature developed on the sila massif granite boulders have developed as a result of spheroidal weathering and by removal of the sandy textured granite the schmidt hammer sh test on boulders and corestones suggests three distinctive degree of weathering from moderately to completely weathered rock and that biotite content is the major controlling factor of the granite mechanical behaviour understanding of the dynamics of this weathering system is crucial to the interpretation of the complex suite of variables that control landscape evolution of granitoid terrains

tectonic constraints on a deep seated rock slide in weathered crystalline rocks abstract deep seated rock slides dsrss recognised as one of the most important mass wasting processes worldwide involve large areas and cause several consequences in terms of environmental and economic damage they result from a complex of controlling features and processes dsrss are common in calabria southern italy where the complex geo structural setting plays a key role in controlling the geometry of the failure surface and its development this paper describes an integrated multi disciplinary approach to investigate a dsrs in palaeozoic high grade metamorphic rocks of the sila massif it focuses on the definition of the internal structure and the predisposing factors of the serra di buda landslide near the town of acri which is a paradigm for numerous landslides in this area an integrated interdisciplinary study based on geological structural and geomorphological investigations including field observations of weathering grade of rocks minero petrographic characterisations geotechnical investigations and in particular fifteen years of displacement monitoring is presented stereoscopic analysis of aerial photographs and field observations indicate that the serra di buda landslide consists of two distinct compounded bodies i an older and dormant body 7 ha and ii a more recent and active body 13 ha that overlies the previous one the active landslide shows movement linked to a deep seated translational rock slide block slide the velocity scale ranges from slow 1 6 m year during paroxysmal stages to extremely slow

multivariate characterization of meandering abstract a suite of 40 morphometric variables has been measured on 57 sections of freely meandering channels from 33 rivers these objective variables are computed from digitized traces of the channel centerline and include measures of sinuosity meander wavelength curvature moments meander asymmetry and pattern irregularity several variables are measured on the half meanders defined by successive inflection points principal components analysis reveals that morphological variations between freely meandering streams can be resolved into four factors related to meander wavelength meander irregularity sinuosity and large scale wandering of the meander axis discriminant analysis using the morphometric variables results in almost perfect separation between natural streams and two theoretical models of meander planform ferguson s disturbed periodic model and howard and knutson s simulation model despite visual similarities the simulated meanders are too regular in size and shape in relation to natural ones perhaps because the interaction of effects of curvature and alternate bars upon topography and flow structure in natural channel bends produces multiple scales of bank erosion not accounted for in present simulation models

self organized criticality in layered lacustrine sediments formed by landsliding landsliding is the dominant mass wasting process in humid temperate uplands and an important regulator of sediment yield from steep land drainage basins information about the magnitude and frequency distribution of landslides has been derived from aerial photography but it has proved difficult to set limits on the long term scaling behavior of landsliding because the requirements of spatial and temporal coherence and the large number of observations necessary to undertake magnitude versus frequency analyses are not easy to fulfill we use a 2250 yr long record of hillslope erosion associated with extreme hydrologic events preserved in sediments from lake tutira new zealand to investigate scaling in landslide deposits both the magnitude versus frequency distribution of sediment layers attributed to landsliding and the distribution of time intervals between landsliding events take the form of power laws the former with an exponent b 2 06 and the latter with an exponent b 1 4 these results suggest that the erosional events originate from a self organized critical process and are in agreement with observations of scaling in turbidite deposits and grain flows in controlled laboratory experiments the implications are that the aggregate behavior of landsliding at the catchment scale is orderly and that the stratigraphic record preserves a unique long term perspective on a fundamental geomorphic process and the extreme hydrologic events that trigger it

minero petrographical features of weathering profiles in calabria southern italy abstract the paper reports interdisciplinary research of weathering profile stages on gneiss with regard to tectonic and landscape evolutions of the western sila grande massif southern italy the outcropping rocks consist of medium to coarse grained biotite garnet and sillimanite gneiss bgs g and medium to coarse grained biotite muscovite migmatitic gneiss m g the bgs g rocks are fractured and weathered with either massive or foliated texture whereas the m g rocks are intensely weathered and fractured with a massive texture and frequent pegmatite veins petrographical and mineralogical variations show that both gneissic rocks bgs g and m g samples underwent weathering processes characterized by a progressive chemical attack on the labile minerals with generation of neoformed minerals and substitution of the original rock fabric the weathering processes produced phyllosilicates and fe oxides neoformed clay minerals and ferruginous products replaced feldspars and biotite during the most advanced weathering stage microfractures and morphological variations occur on the original rock and thereby affect the surrounding landscape processes the weathering profile mineralogy and rock textures viewed in the context of landscape evolution provide useful insights into the widespread slope movement phenomena in the sila grande massif gneiss

a spheroidal weathering model coupling porewater chemistry to soil thicknesses during steady state denudation abstract spheroidal weathering a common mechanism that initiates the transformation of bedrock to saprolite creates concentric fractures demarcating relatively unaltered corestones and progressively more altered rindlets in the spheroidally weathering rio blanco quartz diorite puerto rico diffusion of oxygen into corestones initiates oxidation of ferrous minerals and precipitation of ferric oxides a positive v of reaction results in the build up of elastic strain energy in the rock formation of each fracture is postulated to occur when the strain energy in a layer equals the fracture surface energy the rate of spheroidal weathering is thus a function of the concentration of reactants the reaction rate the rate of transport and the mechanical properties of the rock substitution of reasonable values for the parameters involved in the model produces results consistent with the observed thickness of rindlets in the rio icacos bedrock 2 3 cm and a time interval between fractures 200 300 a based on an assumption of steady state denudation at the measured rate of 0 01 cm a averaged over times longer than this interval the rate of advance of the bedrock saprolite interface during spheroidal weathering the weathering advance rate is constant with time assuming that the oxygen concentration at the bedrock saprolite interface varies with the thickness of soil saprolite yields predictive equations for how weathering advance rate and steady state saprolite soil thickness depend upon atmospheric oxygen levels and upon denudation rate the denudation and weathering advance rates at steady state are therefore related through a condition on the concentration of porewater oxygen at the base of the saprolite in our model for spheroidal weathering of the rio blanco quartz diorite fractures occur every 250 yr ferric oxide is fully depleted over a four rindlet set in 1000 yr and saprolitization is completed in 5000 yr in the zone containing 20 rindlets spheroidal weathering thus allows weathering to keep up with the high rate of denudation by enhancing access of bedrock to reactants by fracturing coupling of denudation and weathering advance rates can also occur for the case that weathering occurs without spheroidal fractures but for the same kinetics and transport parameters the maximum rate of saprolitization achieved would be far smaller than the rate of denudation for the rio blanco system the spheroidal weathering model provides a quantitative picture of how physical and chemical processes can be coupled explicitly during bedrock alteration to soil to explain weathering advance rates that are constant in time

a multidisciplinary approach to investigate weathering processes affecting gneissic rocks calabria southern italy abstract the paper focuses on the weathering processes affecting gneissic rocks of the western sila grande massif calabria italy through the development of an interdisciplinary research based on field studies and investigations minero petrographical analyses and geochemical modeling both physical and chemical weathering affect gneissic rocks of the study area where the combination of tectonic and past climatic conditions played an important key role in the development of complex and deep weathering profiles field surveys and cut slope analyses highlight articulated and complex geometric relationships between various classes of weathering i e out of sequence weathering horizons giving rise to a partial or even complete inversion of the normal weathering profile the weathering profile has turned out particularly intense as classes iv v and vi are widespread among the class vi the colluvial soils are prominent in comparison whit the residual soils borehole logs that confirm the intensity and complexity of weathering profiles in deep allow to estimate the presence of weathered rocks to be at least 70 m in thicknesses the main mineralogical modifications linked to weathering processes concern the partial transformation of biotite and the partial destruction of feldspars mainly plagioclases associated with the neoformation of secondary mineralogical phases clay minerals and fe oxides neoformed clay minerals such as sericite illite and mixed layer phases and ferruginous products replaced feldspars and biotite during the most advanced weathering stage results of xrd analyses and geochemical modelling provide a good indication on the secondary mineral assemblage due to the increase of the weathering intensity form class iii to class vi that reflects the different contributions of chemical elements provided by dissolution of silicate minerals into the surrounding groundwater system the chemical composition of the studied rock samples and the oxides variations suggest a removal of some alkali na and k and alkaline earth ca and mg into solution as a consequence of weathering reactions the chemical analysis and the weathering indices cia pia ciw and ciw show a marked alteration process with ferromagnesian minerals and feldspars probably dissolved and leached into the surrounding groundwater system the co2 controlled dissolution of plagioclase appears to be the most important reaction during chemical weathering the progressive dissolution results then dominated by biotite followed by a minor amounts k feldspar chlorite and garnet whereas the sillimanite shows a neglectable amounts the secondary solid phases observed during the geochemical modeling illite followed by vermiculite ferrihydrite and saponite are similar to those found in this natural system the proposed approach could be used to characterize weathered crystalline rocks and related weathering profiles in similar geological setting and the obtained results represent a key point for the evaluation of the control exerted by weathering on landscape evolution under current environmental settings in terms of sediment generation soil erosion rates and mass movements and for the mechanical characterization of weathering profiles for engineering geological purposes

natural radioactivity levels k th u and rn in the cecita lake area sila massif calabria southern italy an attempt to discover correlations with soil features on a statistical base soils can exhibit a complex range of physical mineralogical and chemical features depending on many interrelated factors such as parental rock composition and mineralogy climate topography vegetation amounts and types water infiltration versus runoff soil moisture organic matter presence and types of anthropogenic contaminants and many others radioactivity as measured on these complex systems is consequently perturbed by several mixed effects in order to find out a possible potential relationship among soil properties and experimental data attributable to radioactivities of k th u and rn a detailed investigation has been performed in the cecita lake basin sila grande calabria southern italy most of the soil types outcropping in the cecita lake surroundings belong to the entisol and inceptisol orders usda united states department of agriculture 2006 keys to soil taxonomy 10th edit usda soil survey staff natural resources conservation service washington d c 333 pp representing relatively young poorly to moderately differentiated soils showing features strongly dependent on the nature of the parent rock and the climatic conditions disintegrations contributed by k th u and rn measured respectively in k ppm u and th and kbq m3 rn have been related to 13 a priori known soil unit groups with well defined general features and spatial position the data have been analysed by using graphical and numerical statistical procedures able to manage compositional data in a correct sample space the paper summarises the results of this research and highlights the conclusions drawn from these investigations particularly concerning i the modelling of the high u variability a behaviour that tends to homogenise the differences potentially attributable to soil features with the exception of situations where uranium could be enriched due to adsorption onto iron oxi hydroxides and or clay minerals or concentrated in argillic horizons due to illuviation ii the discovering of the discriminative effect of the k th ratio values particularly for soil groups where th behaviour as other tetravalent actinides is strongly affected by the presence of mineral colloids or where the presence of clays affects the trapping of k iii the clustering of the a priori known soil groups in four new sets characterised by internal similarities for rn values for which the morphology appears to be the most important discriminative effect

failure mechanisms and stability analyses of granitic boulders focusing a case study in galicia spain abstract granitic boulders are widespread geomorphological elements particularly found in humid granitic areas although they seldom represent a hazard for people or infrastructures sometimes their location in steep or natural slopes may jeopardise their stability and potentially affect people or infrastructures in addition their complex geometry makes the instability mechanisms difficult to identify so it is even more difficult to compute factors of safety regarding their stability in this paper the authors analyse potential failure mechanisms of granite boulders based on analytical mechanic calculations and physical tilt tests permitting understanding the phenomena under scrutiny then they study the stability of one of these boulders the pena do equilibrio or equilibrium rock to do that they resort to standard geotechnical characterization and advanced geometrical characterization derived from uav photogrammetric and 3d laser scanning of the boulder the presented results exemplify how the application of these recently available topographic technologies in combination with rock mechanics approaches enable a rigorous analysis of the stability of granite boulders

geomorphic constraints on landscape sensitivity to climate in tectonically active areas abstract the geomorphology of fluvial landscapes is known to record information about uplift rate spatial patterns of faulting and tectonic history data is far less available when addressing the sensitivity of common geomorphological metrics such as channel steepness to climatic boundary conditions we test the relationship between channel steepness and precipitation rate by measuring a large number of channels in different mountainous areas these regions exhibit a tenfold variation in precipitation rate between them 100 1000 mm y 1 but have similar uplift rates allowing the tectonic variable to be controlled by accounting for the orographic coupling of rainfall with uplifted topography we find that channel steepness is significantly suppressed by higher precipitation rates in a measurable way that conforms to simple stream power erosion laws and empirical constraints on their parameters we demonstrate this using modern and estimated glacial precipitation rates and climate emerges as an important quantifiable control on channel geometry these findings help to explain why highly variable measurements of channel steepness are reported from different locations and provide important empirical constraints on how climate shapes tectonically active landscapes

geomorphic expression of active tectonics in a rapidly deforming forearc sila massif calabria southern italy we examine the tectonic geomorphology of la sila calabria southern italy a high standing 1500 m plateau surrounded by crustal extension with map dem and field data these data are used to constrain a simple geodynamic model that describes short wavelength deformation of the plateau rim topographic metrics including drainage patterns river longitudinal profiles and swath profiles are consistent with field stratigraphic relationships collectively suggesting that local tectonic deformation is embedded within a broader regional uplift that has increased the mean elevation of the sila plateau during the quaternary the concavity steepness and length gradient index of modeled river longitudinal profiles proved to be the most useful metrics for recording the effects of locally active faults a previously unrecognized horst on the northeastern portion of the plateau was identified with these data nevertheless the core of the sila plateau remains relatively undeformed with respect to its flanks which are characterized by steep fault bounded escarpments active extension has dropped base level for and unloaded the plateau rim causing deep fluvial incision and associated flexural uplift of the footwall this footwall uplift helps maintain a separate external and nearly radial drainage away from the plateau along its flanks and a nearly closed drainage for the plateau interior a drainage divide roughly correlates with the plateau rim inhibiting the process of drainage integration through the sila interior and subsequent landscape dissection as a result geomorphic processes driving erosion of the sila upland are lagging behind the tectonic processes that have driven rock uplift leading to an overall increase in mean surface elevation these results underscore the importance of the lag times a landscape may endure in transforming from one tectonic and base level condition to another we conclude that the calabrian forearc has a similar geomorphic evolution as the more northern apennines consistent with the emerging view that growth of apennine topography has been recent quaternary rapid and possibly decoupled from rock deformation in the orogenic wedge

modelling river history and evolution over the last few decades a suite of numerical models has been developed for studying river history and evolution that is almost as diverse as the subject of river history itself a distinction can be made between landscape evolution models lems alluvial architecture models meander models cellular models and computational fluid dynamics models although these models share some similarities there also are notable differences between them which make them more or less suitable for simulating particular aspects of river history and evolution lems embrace entire drainage basins at the price of detail alluvial architecture models simulate sedimentary facies but oversimplify flow characteristics and computational fluid dynamics models have to assume a fixed channel form while all these models have helped us to predict erosion and depositional processes as well as fluvial landscape evolution some areas of prediction are likely to remain limited and short term owing to the often nonlinear response of fluvial systems nevertheless progress in model algorithms computing and field data capture will lead to greater integration between these approaches and thus the ability to interpret river history more comprehensively

thermal weathering of granite spheroidal boulders in a dry temperate climate northern dobrogea romania weathering microforms associated with exfoliation were investigated on 40 granitic spheroidal boulders identified on pricopan ridge m cin mountains in order to establish a spatial distribution pattern continuous thermal monitoring allowed the frequency and intensity distribution assessment of short term temperature changes triggered by summer storms of intense day night amplitudes and frost cycles across a uniform rounded boulder rock strength estimated by schmidt hammer tests differentiates a significantly weaker resistance on the southern face of the boulders rebound values of 27 to 33 in comparison with the northern face 43 50 the lowest resistance of the north south cross boulder profile corresponds to the southern gentle slopes 0 45 thus defining the most susceptible area to exfoliation and other weathering processes it is argued that this low resistant sector fits well with the maximum frequency and intensity of thermal processes recorded on the low and mid slopes 0 45 of the boulders south side with small differences from one process to another whilst the sector of 20 to 30 south corresponds to the peak activity of all in accordance the overlay map of exfoliated surfaces places the high frequency area on a spherical cap developed similarly between 5 north and 45 south the smallest exfoliated surfaces normally appear around 30 south and are inferred to extend in time both to the boulder top and downslope the correlations between the frequency intensity maps of thermal processes and the frequency map of exfoliated surfaces point to a complementary action in the exfoliated surfaces development of the short term temperature changes and diurnal cooling and heating due to the directional insolation effect as similarly inferred in the development of meridional cracks copyright 2016 john wiley sons ltd

climate and relief induced controls on the temporal variability of denudation rates in a granitic upland how soil erosion rates evolved over the last about 100 ka and how they relate to environmental and climate variability is largely unknown this is due to a lack of suitable archives that help to trace this evolution we determined in situ cosmogenic beryllium 10 10be along vertical landforms tors boulders and scarps on the sila massif to unravel their local exhumation patterns to develop a surface denudation model over millennia due to the physical resistance of tors their rate of exhumation may be used to derive surface and thus soil denudation rates over time we derived soil denudation rates that varied in the range 0 0 40 mm yr 1 the investigated boulders however appear to have experienced repositioning processes about 20 25 ka bp and were therefore a less reliable archive the scarps of the sila upland showed a rapid bedrock exposure within the last 8 15 ka overall the denudation rates increased steadily after 75 ka bp but remained low until about 17 ka bp the exhumation rates indicate a denudation pulse that occurred about 17 5 ka bp since then the rates have continuously decreased we identify three key factors for these developments climate topography and vegetation between 75 and 17 ka bp climate was colder and drier than today the rapid changes towards warmer and humid conditions at the pleistocene holocene transition apparently increased denudation rates a denser vegetation cover with time counteracted denudation topography also determined the extent of denudation rates in the upland regime on slopes denudation rates were generally higher than on planar surfaces by determining the exhumation rates of tors and scarps soil erosion rates could be determined over long timescales and be related to topography and particularly to climate this is key for understanding geomorphic dynamics under current environmental settings and future climate change

comparison of deeply buried paleoregolith profiles norwegian north sea with outcrops from southern sweden and georgia usa implications for petroleum exploration abstract for the first time on the norwegian continental shelf deeply buried paleoregolith profiles have been identified as part of the petroleum reservoirs in recently discovered oil fields on the utsira high norwegian north sea reservoir properties porosity and permeability in the granitic basement on the utsira high are mainly the result of physical and chemical alteration of the rock occurring in the near surface environment during sub aerial exposure of the high in the mesozoic evaluating the reservoir potential of altered basement rocks requires a different approach than in conventional petroleum exploration in this paper macroscopic mineralogical and micromorphological alteration features observed in two deeply buried paleoregolith profiles are compared with surface paleoregoliths from ivo klack sweden and georgia usa the paleoregolith profiles are subdivided into specific weathering facies altered coherent rock facies saprock facies and saprolite facies based on the rock fabric and mechanical strength the reservoir potential of each weathering facies is controlled by the type and degree of alteration in the altered coherent rock facies porosity and permeability is mainly controlled by joints and microfractures that developed prior to subaerial exposure of the granitic pluton in the saprock facies intensified chemical dissolution of plagioclase enhanced porosity and the development of mesofractures improved the connectivity between pores in the saprolite facies progressive dissolution of plagioclase creates porosity but the precipitation of clays within voids and mesofractures has a destructive effect on the overall reservoir properties the deeply buried paleoregolith profiles from the utsira high display comparable macroscopic mineralogical and micromorphological alteration features to what was observed in surface paleoregoliths from ivo klack and georgia outcrop studies may therefore be an important tool when evaluating the reservoir potential in subsurface paleoregoliths

the impact of dolomite and plagioclase weathering on the chemistry of shallow groundwaters circulating in a granodiorite dominated catchment of the sila massif calabria southern italy abstract this work is aimed at investigating the weathering processes of the granodiorites cropping out in a small catchment of the sila massif the mineral constituents in this granodiorite are plagioclase often zoned with a ca rich core and a na rich rim quartz chlorite k feldspar white mica and epidote during this study dolomite was discovered in local stream sediments as separate monomineralic grains probably resulting from erosion of veins cutting the crystalline rocks prevailing dissolution of foreign dolomite and a ca rich plagioclase is suggested by the ca mg hco3 chemical composition of local groundwaters and stream waters which is rather unexpected for waters interacting with granitoid rocks these qualitative observations are quantitatively confirmed by reaction path modelling of the weathering processes occurring in the study area which was carried out using the eq3 6 software package version 8 0 and the double solid reactant method indeed it was possible to ascertain that the release of both major dissolved constituents and several trace elements ba co cr fe mn ni pb sr v and zn from rocks to waters is chiefly controlled by the dissolution of foreign dolomite and the ca rich core of zoned plagioclases

geomorphic constraints on uplift history in the aspromonte massif southern italy abstract the landscape morphology of the aspromonte massif southern italy shows hanging low relief surfaces that correlate with uplifted landsurfaces which are preserved all around the massif the drainage network has deeply incised the high standing low relief landscapes seen here as being the remnants of phases of relief smoothing prior to strong uplift that has affected the area since the middle pleistocene gis aided estimation of the rock volumes eroded since the late early pleistocene indicate high variability in denudation rates between the gently rolling landscapes and the river valleys in this framework longitudinal river profiles are examined for 42 river channels to constrain multiple non equilibrium conditions and to reconstruct the long term uplift history of the massif most profiles consist of three four segments separated by knickpoints and suggest a complex incision pattern longitudinal profiles reveal two upper low gradient channel segments a zone of steep channels further down the low relief landsurface margin and a very steep lower channel segment particularly in the western quadrant upper channel segments correspond to the relict landscape rlandscape a high standing landsurface on top of the massif and the hanging landscape hlandscape a landsurface surrounding the rlandscape respectively steeper middle and lower segments are the result of two phase river incision that is linked to changes in regional uplift rates and subordinately to rock strength properties indeed analysis of river longitudinal profiles could indicate initially relatively slow aspromonte uplift during the early pleistocene and then pulses of rapid uplift during the middle late pleistocene multi segment river longitudinal profiles are therefore evidence of the transient landscapes of aspromonte in response to pulsed massif uplift

character and origin of deep arenaceous weathering mantles on the bega batholith southeastern australia summary arenaceous weathering mantles on the bega batholith southeastern australia are similar to those described from europe by millot as in europe they have been formed by hydrothermal alteration of the parent rock and later by chemical weathering of biotites and feldspars but comparisons with nearby torfields shows that their distribution is determined largely by mineralogical variations in the parent rock unlike the examples cited by millot in the bega mantles kaolinite is the dominant clay mineral nonetheless these mantles seem to be contemporary not relict features and apparently formed under a temperate climate

structural and geomorphological constraints on active normal faulting and landscape evolution in calabria italy calabria is one of the fastest uplifting and most seismically active regions in the mediterranean yet the time averaged c 10 6 years rates of normal faulting remain poorly constrained here we use digital elevation model analysis geological cross sections and a compilation of published data to quantify systematically along strike the fault throws and time averaged throw rates of the serre cittanova armo east crati and west crati faults we show that regional uplift has uplifted both their hanging wall and footwall blocks by c 200 400 m and the aspromonte massif by up to c 1150 1300 m we find that these faults have throws between c 640 and 1430 m and throw rates between c 0 6 and 1 4 mm a 1 their footwall ranges have variable proportions of inherited relief up to c 300 800 m the channels draining these ranges reflect the active normal faulting and relief in their steepness indices becoming c 5 8 m 0 9 steeper for each 0 1 mm a 1 throw rate increment and each 100 m relief increase finally the presence of knickpoints suggests that these channels are transiently responding to changes in relative base level which could be due to fault linkage or regional strain rate increases for the southern calabrian faults and to regional uplift acceleration in the case of the crati faults supplementary material topographic profiles of the marine terraces and long profiles of rivers are available at https doi org 10 6084 m9 figshare c 3689464

evaluation of a linear bank erosion equation field surveys and aerial photographs were used to measure the rate of migration of a bend of the brandywine creek near chadds ford pennsylvania velocities near the bank were measured in the field during high flows and also estimated by solving a form of the st venant equations engineering properties of the bank soils and the spatial density of trees growing along the bank were also measured the data indicate that rates of bank migration are linearly related to the magnitude of the near bank velocity if the st venant equations are used to estimate the near bank velocity the data also suggest that erosion rates are proportional to ub u where ub is the near bank velocity and u is the reach averaged velocity in addition rates of bank migration are reduced where the density of silver maples acer saccharinum is high boxelder acer negundo and white ash fraxinus americana are also found along the bend but these species do not noticeably influence rates of bank migration

micro scale damage characterized within part of a dismembered positive flower structure san jacinto fault southern california usa abstract to better understand the processes that control sub grain fracturing in fault damage zones we studied micro scale damage in sandstones adjacent to the san jacinto fault sjf where it is exhumed from a total depth of 220 m beneath a northeast verging thrust that comprises part of a relic and dismembered flower structure the thrust places high grade gneiss of the pre middle cretaceous burnt valley complex over sedimentary rocks of the pleistocene bautista formation an 10 12 cm thick zone of cataclasite is present along the northeast side of the fault adjacent to a narrow black ultracataclasite core non pervasive microscopic damage characterized by pulverized sand grains extends outward from the zone of cataclasites tens of meters such textures are better developed in sandstones that contain

elemental mobility during the weathering of exposed lower crust the kinzigitic paragneisses from the serre calabria southern italy weathering and transportation studies of the chemical composition of sediments have determined how surface fractionation processes modify the elemental signature due to provenance and tectonic setting of siliciclastic rocks although the bulk of the exposed upper continental crust comprises granitoids metamorphic rocks from the intermediate to lower crust may be in some geological contexts the provenance of siliciclastic sediments a preferential enrichment of the lree relative to the hree is observed in weathered garnet rich kinzigitic paragneisses from the calabrian arc southern italy this fractionation is due mostly to the mineralogical control exerted by monazite which is concentrated in the silt size fraction of the soil however a significant part of hree released during garnet alteration is trapped by secondary minerals in the clay sized fraction of the soil in a manner similar to pb2 and cs cations of some concern in environmental geochemistry in the weathered material monazite is also important in controlling the eu anomaly the negative size of which increases with increasing th addition the eu anomaly in the clay sized fraction of the soil is very similar to that of the fresh rock suggesting that the eu eu index in pelitic sediments deriving from the intermediate to lower crust may be regarded as a reliable indicator of parental affinity other provenance indicators include la th which share the same mineralogical control indicators of contrasting mafic and felsic provenance e g sc th should be used with care

controls on rock weathering rates by reaction induced hierarchical fracturing abstract weathering of rocks takes place through complex processes involving an intimate coupling between mechanical disintegration of the rocks and interactions between the exposed rock surface the hydrosphere and the biosphere it is still poorly understood how this coupling affects weathering rates and patterns produced by weathering here we show that the observed spheroidal weathering patterns in basaltic intrusions dolerites in the karoo basin in south africa are created through volume expanding reactions which set up stresses that not only lead to spalling of spheroidal layers of rock but also drive a large scale hierarchical fracturing process by which the dolerite is continuously undergoing domain division the fracture processes generates new reactive surface area in a self accelerating manner thus providing a first order control on the total weathering rate

fossil cryogenic features in paleosols of southern italy characteristics and paleoclimatic significance the work presents the results of a study of two paleosols located at 1350 m a s l on the sila massif in southern italy the purpose of this research is to examine paleoenvironmental conditions during the last glaciation based mainly on soil morphological micromorphological and sedimentological data these two paleosols contain climatically sensitive cryogenic features including a sand wedge an ice wedge cast silt veins silt lenses reticulate silt veins and matrix lenses these features are interpreted to indicate that during the last glacial maximum this area in southern italy experienced conditions characterized by very low temperature little snow cover and great aridity

role of lichens in weathering of granodiorite in the sila uplands calabria southern italy this paper explores the role of five recurrent epilithic lichen species aspicilia intermutans nyl arnold xanthoparmelia pulla ach o blanco a crespo elix d hawksw lumbsch rhizocarpon lecanorinum anders tephromela atra huds hafellner and lecanora bolcana pollini poelt which encrust granodiorite spheroidal boulders exposed in the sila uplands calabria southern italy in weathering of plutonic rocks in a typical mountainous mediterranean environment a detailed investigation was carried out on the lichen rock interface of each species by comparing them mutually and with lichen free granodiorite samples for this purpose the lichen species were sampled together with the encrusted rock surface for detailed mineral petrographic analyses performed in thin and ultra thin sections optical and scanning electron microscopy of these sections and of bulk samples permitted us to highlight the peculiar modes of physical and chemical attacks of lichen thalli and hyphae on and into the substratum for each species crack systems often parallel to the outer rock surface appear often intruded by hyphae which cause rupture of primary minerals with detachment and progressive incorporation of their fragments into the thallus in particular the species l bolcana and t atra revealed an unexpected partly endolithic behavior presumably enhanced by the presence of rock fractures earlier generated by other physical breakage processes already affecting the spheroidal boulders in the sila mountains dissolution features often affect primary minerals even quartz that may show very peculiar patterns which are suggestive of a biologically induced control various phyllosilicate clay minerals were identified using sem eds microprobe analyses and ft ir spectroscopy which also enabled the identification of possible amorphous silica or quartz micrograins rhizocarpic acid and carotenoid at the encrusted granodiorite interface in contrast neither oxalic acids nor oxalates were detected

fission track analysis of the crystalline basement rocks of the calabrian arc southern italy evidence of oligo miocene late orogenic extension and erosion abstract fission track analysis is used to provide low temperature and time constraints on the late orogenic cooling and exhumational history of the crystalline basement rocks of the calabrian arc southern italy 65 samples yielded 57 apatite fission track ages 54 zircon fission track ages and 25 apatite confined fission track length distributions interpretation of this data reveals a phase of increased cooling rates related to exhumation between approximately 35 ma mid oligocene and 15 ma middle miocene evidence from the sedimentary record indicates significant oligo miocene erosion related to this period of exhumation new chronological constraints are also applied to localised late orogenic extensional tectonism that has recently been identified within the basement rocks of the calabrian arc this information is used to produce a new model of the oligo miocene tectonic evolution of the calabrian arc it proposes that the crystalline basement rocks were part of a critical orogenic wedge between the mid oligocene and the middle miocene

weathering of gneiss in calabria southern italy abstract the effects of weathering in a mediterranean climate on the mineralogy and microfabric of paleozoic gneiss of the sila massif calabria southern italy have been studied field observations show highly weathered rock forms a residual soil micromorphological and mineralogical properties of bedrock and saprolite show that the weathering process is characterized by at least two major stages having two distinct rock microfabrics in the first stage the morphological features of the original rock are preserved and weathering is manifested mainly by microfracturing and large portions of the rock remain unaltered the second stage of weathering involves further development of microcracks and progressive chemical attack on the minerals this latter stage occurs along both compositional and microstructural discontinuities with etch pitting of feldspar and neoformation of clay minerals and ferruginous products replacing feldspar biotite and iron bearing garnet the determination of quantitative petrographic indices provides a measure of the various stages of weathering

the interplay of geomorphic processes and soil development in an upland environment calabria south italy abstract five representative soil profiles outcropping in the area around the cecita lake calabria south italy were characterised by field work chemical and mineralogical analyses optical and scanning electron microscopy interactions among weathering pedogenesis and geomorphic processes are emphasised in an attempt to link the results obtained at different scales of observation the important role of topography in controlling soil development or removal by erosive processes is discussed in relation to the natural geomorphological context and the effects of human pressure both present day and relict features were recognised in the studied soils and discussed in terms of environmental conditions and climatic changes the chemical composition of volcanoclastic components identified in some soil horizons with andosol like field appearance coupled with pedogenetic features contributed useful chronological constraints for the reconstruction of late quaternary geomorphic events

causes of scaling on bush hammered heritage ashlars a case study plaza mayor of madrid spain masons have traditionally used granite anisotropy to cut and lay the stone scaling a common type of granite decay is observed worldwide this study explored the relationship between weathering and cut planes in heritage ashlars specifically in the stone on madrid s plaza mayor whose construction dates back to 1590 the 71 rectangular granite columns that support its porticoes are oriented towards the four cardinal points all 71 have one exposed side that faces the square one protected side facing inward and two semi protected sides perpendicular to the other two the sides of the columns are also oriented to the points of the compass this study aimed to identify the prevailing orientation of scaling if any in the granite ashlars and to determine how this process is affected by climate microclimate orientation use hewing and exfoliation microcracks all four sides of the 71 columns were mapped 284 in all to analyse scaling height distribution and orientation the findings showed that the microcracks are vertically oriented and decline in density and length with depth from the surface scaling was observed on the lower ashlars in the columns to a maximum depth of 3 mm determining the direction of exfoliation microcracks is imperative to understanding decay mechanisms in granite ashlars and sculptures and that information must be taken into consideration when applying conservation treatments

terrestrial laser scanning used to determine the geometry of a granite boulder for stability analysis purposes abstract in this paper we analyze the use of terrestrial laser scanning tls technologies to determine the geometric features of a granite boulder accurate determination of these features is a key to performing a reliable stability analysis of the boulder tls has been demonstrated to have important advantages over traditional measurement techniques such as for example direct methods based on the use of tapes or indirect methods such as topography or close range photogrammetry tls equipment enables thousands of points to be accurately measured in minutes in our study tls measured points were used to model the surface of a boulder geometric parameters were then calculated namely centre of gravity volume of the boulder and dimensions of the boulder contact area with the ground taking into account mechanical and environmental factors these parameters were used to calculate the safety factor of the boulder against toppling and sliding our results show that when seismic activity in the region is taken into consideration the boulder is borderline stable unstable

weathering zones on metamorphic rocks from rio de janeiro physical mineralogical and geomechanical characterization abstract this work presents and analyzes results obtained on a research program aiming at the characterization of materials belonging to weathering profiles developed in the three most common metamorphic rocks occurring in rio de janeiro brazil leptinite kinzigite and augen gneiss initially a comprehensive field description is presented in order to point out the main weathering patterns observed for these rocks samples from different weathering levels were identified and tested in order to determine their mineralogical physical and geomechanical properties the obtained results are discussed and an evaluation of the influence of weathering on rock properties is presented correlations between the physical and mechanical properties of the tested materials are also presented

recent reverse faults and landslides in granitoid weathered profiles serre mountains southern calabria italy abstract it is rarely possible to identify reverse faults that bring portions of substratum solid rock to lie above decomposed rock only where the differences between the fresh rock and weathered rock are very clear is it possible to recognise such faults a reverse profile is defined as a slope profile in which fresh rock granitoids overlaps rocks which have been greatly altered by mature weathering saprolite of granitoids such a profile occurs along the slopes of molini valley to the south of the village of fabrizia calabria southern italy and we interpret the morphological mechanical and structural evidence as typical of a reverse fault the mineral petrographic analysis of the grus on the bed of the fault and of the cover of relatively fresh rock schmidt hammer 18 35 confirms that the granular framework can be attributed to subaerial alteration and not to mechanical deformation the study area is located at the centre of the largest kinematic body of southern calabria the serre massif exclusively granitoids until now considered to be only affected by extensional tectonics creating high angle normal faults in this area the tectonic processes the thickness and spread of granitoid weathering mantles and the depth of the valleys give rise to several landslides these are generally translational slides with ample cut surfaces between the weathered body and the underlying fresh rock as a consequence very large deposits in the valleys can be found mostly produced by debris flow processes at the foot of the slopes around fabrizia coarse debris avalanches with cobbles having a volume of over 0 3 0 4 m 3 are occasionally observed unless there is widespread development of a reverse weathering profile on the slopes above

percolation theory applied to simulated meander belt sandbodies abstract the evolution of meander belts is simulated using a single channel model of freely meandering dynamics with constant discharge and no avulsion this means that lateral migration of the river is not confined by a valley i e it takes place on a sloping plain and that chute cutoffs and avulsions do not occur the meander belt undulates within a relatively narrow tract roughly 50 channel width units wide this limited width is caused by a river planform fractal geometry in the form of self affine scale covariance of meanders the simulated meander belt pattern compares well with actual meander belts of free meandering rivers suggesting that the assumptions of the model are reasonably realistic for freely meandering rivers in nature the spatial sandbody distribution in deposits from this system is an outcome of the processes of isolation of point bars from the active river by neck cutoffs and vertical attenuation by subsidence and or deposition for a constant total subsidence and deposition tsd rate the vertical spatial distribution is well described by percolation theory this was demonstrated by analysis of a simulated spatial distribution of point bar sandbodies the tsd rate controls the density of single sandbodies and amalgamated sandbody clusters within the formation and is therefore equivalent to the inverse of the probability of site occupation in site percolation models percolation theory predicts the existence of a critical tsd rate in the vertical direction and that sandbody clusters follow a power law size distribution over a large scale range at the critical value these predictions were confirmed the analysis indicates that a scaling law of composite and single sandbodies exists at the percolation threshold the threshold of sandbody connectivity at a given scale n m m a m 1 where n m m is the number of single or amalgamated sandbodies larger than size m area of point bar enclosed by an oxbow lake or area of amalgamated cluster of point bars the exponent is the scaling exponent d and a is a constant of proportionality both parameters go to a minimum value at the critical threshold

jointed source rock and fluvial gravels controlled by rosin s law a grain size study in calabria south italy the primary distributions of the untransported source rocks are unimodally distributed and very positively skewed the average sand fraction is only 4 only 6 of the distributions are lognormal 94 follow the rosin distribution which is typical for products of technical breakage and milling processes twelve of the 19 river mounth sediments are bimodally distributed with a primary mode in the gravel range a marked valley in the 2 mm range and a secondary mode in the sand range the seven rivers with unimodal sediments also have their modes in the gravel range both unimodal bimodal sediments consist of on the average 74 boulder and gravel 25 sand and 1 silt and clay surprisingly 77 of the gravel modes of the river sediments also follow the rosin distribution only the sand fractions of both the unimodal and bimodal sediments are lognormally distributed the rosin distribution of the calabrian river gravel is interpreted as a source specific primary feature the lognormality of the sand mode in contrast as a transport specific secondary feature since the jointed and weathered source rocks contain only 4 sand they cannot be the only source of the 25 sand in the river sediments the sand must also come from other sources such as soil building and transport wear modified journal abstract

an overview of the role of weathering in the production of quartz silt abstract quartz silt is a widespread detrital sediment with large aeolian loess and alluvial silt deposits forming important components of many contemporary landscapes despite research findings which indicate that a range of opportunities exist for the comminution of quartz into silt particles within a wide variety of geomorphic environments e g glacial grinding fluvial comminution aeolian abrasion frost weathering salt weathering insolation weathering and deep weathering the glacial aeolian hypothesis has traditionally been favoured as the most likely explanation for loess formation and loess is seen as primarily a quaternary phenomenon as a consequence there has been a tendency to underestimate sediment inputs into loess systems by geomorphological processes operating within pre quaternary environments in particular earth scientists may have considerably underestimated the role of weathering in global silt generation as there are now many references to the existence of a patchy but widespread distribution of pre quaternary weathering profiles across the glacial and periglacial landscapes of the northern hemisphere e g north america british isles north and central europe landscapes within which many of the classical loess deposits are located these observations suggest that weathering profiles may have covered large tracts of the northern hemisphere land surface prior to the quaternary glaciations this in turn may have important implications for quartz silt generation as 1 experimental studies indicate that many weathering processes are capable of generating significant quantities of silt sized debris and 2 particle characteristics displayed by saprolitic material that has developed on quartz rich crystalline source rocks often include significant quantities of either silt sized material or quartz grains that are weakened by weathering derived microfractures thus weathering profiles may represent mines of actual and potential quartz silt available for release into sedimentary systems when these profiles are subsequently reworked by geomorphological processes such as glacial fluvial and aeolian erosion

mineralogical and chemical changes of soil and stream sediment formed by intense weathering of the danburg granite georgia u s a abstract a series of soil and stream sediments developed during intense weathering on the metaluminous danburg granite northeastern georgia u s a have been analyzed mineralogically and chemically the concentrations of ba na rb and cs in the silt and coarser fractions are controlled mainly by feldspars and biotite hf is controlled by zircon and the ree rare earth elements and th are largely controlled by sphene variations in feldspar sphene and zircon may produce small variations in eu sm and la lu ratios ferromagnesian minerals control ta fe co sc and cr concentrations the mineralogical and chemical composition of the danburg granite is more closely reflected in the silt than in the sand or gravel fractions of stream sediments in the silt the contents of rb ree th ta fe co and sc and the ratios of la sc th sc la co th co eu sm and la lu are similar to those in the unweathered granite in contrast these element contents or ratios in the sands and gravels are 0 05 3 the concentration in the unweathered granite ta and ba contents are an exception to the above the ta and ba contents of the sands and gravels are similar to those of the granite in the kaolinite halloysite clays the content of na is depleted relative to the source rb cs ba hf and ta are depleted or enriched in the clays relative to the source while the ree th fe co sc and cr are enriched the eu sm eu anomaly size and la lu ratios and the ree patterns of the clays are similar to those of the source thus the mineralogy and element contents of a siltstone developed from metaluminous granitic sources during intense weathering would be expected to be more similar to the source rock than the sandstones and conglomerates claystones should contain similar ree patterns and eu sm ratios as the source rock but such fine grained sediments might represent much larger areas of source rocks than the more locally derived sandstones or conglomerates

geochemical signature of provenance in sand size material in soils and stream sediments near the tobacco root batholith montana u s a abstract trace element geochemistry of sandstones are being used to determine provenance we have conducted preliminary and limited experiments to determine to what extent daughter sands retain the geochemical signature of parent rocks six sets of first order stream sediments soils from adjacent slopes and a variety of parent rocks were collected from southwestern montana u s a sampling in a low relief area ensured that climate and residence time of soils on slopes could be eliminated as variables sand size fractions of stream sediments and soils and the corresponding parent rocks granodiorite quartz monzonite granite gneiss biotite tonalite gneiss and amphibolite were analyzed for most major elements and selected trace elements petrologic modal analysis of the parent rocks and the 0 25 0 50 mm fraction of each sand was done to monitor major mineralogic control if any on chemical compositions of the samples our data show that the abundances of the si and al in sediments do not discriminate provenance abundances of ca mg fe and ti may broadly distinguish between sands derived from metamorphic and igneous source rocks at least in the area studied differences in abundances of the ba and th and the ratio of la lu between granitic tonalitic and amphibolitic parent rocks are preserved in the daughter sediments that we studied however the size of the eu anomaly in the ree patterns of different daughter sediments is not diagnostic of parent rocks abundances of co and sc distinguish between sediments derived from felsic and mafic rocks a better provenance discrimination is obtained if the ratios la sc th sc la co ba sc and ba co are used petrologic modal data show that mineral contents and chemical compositions of parent rocks are compatible with each other the chemical composition of the sands may be roughly correlated to the petrological modal data but the abundances of some minor and trace elements of sediments cannot be inferred from modal mineralogy this is expected because these elements may concentrate in accessory minerals and or may weather out into aqueous or clay mineral fractions it is also compatible with conclusions of previous studies that some of these elements do not reside in sand size fractions of siliciclastic sediments

weathering profiles in granitoid rocks of the sila massif uplands calabria southern italy new insights into their formation processes and rates abstract in this paper we characterized several weathering profiles developed on granitoid rocks in the sila massif upland calabria southern italy integrating detailed macro and micromorphological observations with physico mechanical field tests and petrographic mineralogical and geochemical analyses we focused our attention on the main weathering and pedogenetic processes trying to understand apparent discrepancies between weathering grade classes based on field description and geomechanical properties and two common weathering indices such as the micropetrographic index ip and the chemical index of alteration cia our results showed that sericite on plagioclase and biotite chloritization that represent inherited features formed during late stage hydrothermal alteration of granitoid rocks may cause an overestimation of the real degree of weathering of primary mineral grains under meteoric conditions especially in lower weathering grade classes moreover the frequent identification of fe mn oxides and clay coatings of illuvial origin rather than or in addition to those formed in situ both at the macro and microscale may also explain an overestimation of the weathering degree with respect to field based classifications finally some apparent inconsistencies between field geomechanical responses and chemical weathering were interpreted as related to physical weathering processes cryoclastism and thermoclastism that lead to rock breakdown even when chemical weathering is not well developed hence our study showed that particular caution is needed for evaluating weathering grades because traditional field and geochemical petrographic tools may be biased by inherited hydrothermal alteration physical weathering and illuvial processes on the basis of chronological constraints to soil formation obtained from a 42 ka old volcanic input mixed to granite parent materials detected in the soil cover of the sila massif upland a first attempt to estimate soil formation rates was achieved for different depths of corresponding weathering profile zones soil formation rates ranged from 0 01 0 07 mm a 1 for a and bw horizons weathering class vi to 0 04 0 36 mm a 1 for the underlying saprolite c and cr layers class v by comparing these results with the corresponding erosion rates available in the literature for the study area that range from

weathering and pedogenesis in the sila grande massif calabria south italy from field scale to micromorphology abstract weathering and soil features in the upland landscapes developed on granitic terrains of the sila grande massif calabria south italy have been studied in this work the attempt to link field scale and micromorphological observations in order to better understand the main weathering processes and their controlling factors is revealed to be very powerful six soil profiles in the area around the cecita lake representative of different geomorphological units were characterised by field work optical microscopy and sem eds analysis a strong influence on weathering and pedogenesis by micro scale features of primary minerals and parent rock fabrics is shown key roles are played also by relief in the development and preservation or stripping of regolith soil mantles in relation to natural and man induced phenomena by time controlling rates and degree of development of the main weathering features by climate in terms of type and intensity of dominant processes

the origin and implications of some erosional landforms etching is a mechanism of landform development involving two stages or phases first a regolith develops as a result of interaction between groundwaters and country rock the surface of contact between the two called the weathering front develops a relief as bedrock weaknesses are exploited by chemical corrosion second the regolith is stripped to expose the weathering front as an etch surface etch forms are widely distributed but are especially well developed and preserved in the relatively stable shield lands they range in scale from the plains and hills of inselberg landscapes to minor features such as boulders gutters basins flared slopes scarp foot depressions and pitted surfaces many etch forms have two ages one related to the period of subterranean preparation the other to the exposure of the erstwhile weathering front many are developed in a variety of rock types as well as in a considerable range of climatic settings etching carries several implications for landform interpretation

mineralogical and textural controls on the weathering of granitoid rocks summary the results obtained in several recent studies provide convincing evidence that potassium rich granitoid rocks are relatively more resistant to weathering than their less potassic counterparts this reflects the fact that microcline and orthoclase are more stable in most weathering environments than calcic plagioclase and biotite relatively slight differences in bulk rock chemical composition can lead to differential rates of weathering in areas of inhomogeneous granitoid terrain thereby leading to the development of topographic features such as inselbergs a second major control on the rate of weathering is rock permeability this is largely a function of degree of microfracturing and jointing in most circumstances grain size and other textural differences probably exert a minor influence on rates of chemical weathering although laboratory tests have shown they may profoundly affect physical strength parameters

grus weathering mantles problems of interpretation abstract grus is an ill defined product of deep weathering of coarse grained rocks whose relationships to other weathering changes remain unclear this paper attempts to address this issue by reviewing a number of examples of coarse saprolites from a variety of climatic and topographic settings grus is the category of weathering mantle that possesses the following characteristics sand gravel 75 100 silt clay

granite landform evolution factors and implications most granite landforms are due to the exploitation of weaknesses especially fractures by meteoric waters and particularly groundwaters moisture attack produces grus which commonly forms the bulk of the regolith in granitic terrains the transition from weathered to fresh rock is typically abrupt and takes the form of a narrow transition zone called the weathering front

grain size of granite and derived grus enchanted rock pluton texas abstract twenty five samples of grus from non vegetated weather pits in granite were sieved and found to be mostly pebble gravel average content of gravel sand and mud was 76 16 and 18 respectively by weight primary grain size modes were between 2 8 23 0 mm and most grus was composed of granite rock fragments twelve granite cores drilled in the same weather pits from which grus was collected were studied in thin section with 856 grains identified mineralogically and measured for size these measurements were recast as sieve data grain size comparisons for each granite grus pair showed that the grain size mode of grus did not follow the crystal size of parent granite granite with average crystal sizes of 23 0 and 4 0 mm formed grus with a primary grain size mode of 5 7 mm for two different sample pairs granite with crystal sizes of 4 0 and 1 0 mm yielded grus with primary grain size modes of 5 7 and 11 6 mm modal size measurements were pooled for the twelve granite grus pairs and the average crystal size of parent granite was found to be 3 4 mm and the average grain size model of derived grus was 5 7 mm folk and patton 1982 have documented micro sheet fracturing of granite as the earliest stage of weathering which explains the lack of correspondence between granite texture and grain size of grus at enchanted rock

the use of the schmidt hammer and equotip for rock hardness assessment in geomorphology and heritage science a comparative analysis rapid field based measurements of rock hardness are of use in investigating many geomorphological and heritage science problems several different methods are now available for taking such measurements but little work has been done to assess their comparability and strengths and weaknesses we review here the capabilities of two types of schmidt hammer classic n type and silver schmidt bl type alongside two types of equotip standard type d and piccolo for investigating rock hardness in relation to rock weathering on various types of sandstone and limestone as well as basalt and dolerite whilst the two schmidt hammers and the two equotips show comparable results when tested at 15 individual sites interesting differences are found between the equotip and schmidt hammer values which may reveal information about the nature of weathering on different surfaces operator variance is shown to be an issue in particular for the equotip devices which also exhibit higher variability in measurements and necessitate larger sample sizes carborundum pre treatment also has varying effects on the data collected depending on the nature of the surface studied the equotip devices are shown to be particularly useful on smaller blocks and in situations where edge effects may affect schmidt hammer readings we conclude that whilst each device contributes to geomorphological research they do not necessarily produce comparable information indeed using schmidt hammer and equotip in combination and looking at any differences in results may provide invaluable insights into the structure of the near surface zones and the nature of weathering processes copyright 2010 john wiley sons ltd

weathering erosion and sediment composition in a high gradient river calabria italy source rock lithology and immediate modifying processes such as chemical weathering and mechanical erosion are primary controls on fluvial sediment supply sand composition and chemical index of alteration cia of parent rocks soil and fluvial sand of the savuto river watershed calabria italy were used to evaluate the modifications of source rocks through different sections of the basin characterized by different geomorphic processes in a sub humid mediterranean climate the headwaters with gentle topography produce a coarse grained sediment load derived from deeply weathered gneiss having sand of quartzofeldspathic composition compositionally very different from in situ degraded bedrock maximum estimated cia values suggest that source rock has been affected significantly by weathering and it testifies to a climatic threshold on the destruction of the bedrock the mid course has steeper slopes and a deeply incised valley bedrock consists of mica schist and phyllite with a very thin regolith which provides large cobble to very coarse sand sediments to the main channel slope instability with an areal incidence of over 40 per cent largely supplies detritus to the main channel sand sized detritus of soil and fluvial sand is lithic estimated cia value testifies to a significant weathering of the bedrock too even if in this part of the drainage basin steeper slopes allow erosion to exceed chemical weathering the lower course has a braided pattern and sediment load is coarse to medium fine grained the river cuts across palaeozoic crystalline rocks and miocene siliciclastic deposits sand sized detritus contributed from these rocks and homogenized by transport processes has been found in the quartzolithic distal samples field and laboratory evidence indicates that landscape development was the result of extensive weathering during the last postglacial temperature maximum in the headwaters and of mass failure and fluvial erosional processes in the mid and low course copyright 2000 john wiley sons ltd

subsurface thermal conductivity assessment in calabria southern italy a regional case study determining the suitability of a local area at a regional or local scale for the geothermal application of low enthalpy systems requires the knowledge of rock thermal conductivity values to evaluate the possibility of low enthalpy heat exchange a digital cartographic tool is also needed to synthesize the thermal properties of the underground this tool should be easily accessible and upgradeable and thus suitable for territorial planning and environmental control in order to address these key issues a methodological approach was developed within the framework of the national vigor project dedicated to evaluating the geothermal potential in southern italy in this paper the region of calabria was selected as a case study around 70 samples that were representative of the main geological formations were collected from all over the area thermal property tests were carried out both in dry and wet conditions using a thermal device in accordance with the modified transient plane source method the thermal conductivity values were then compared with data from the international literature in order to consider the influence of the entire stratigraphic sequence on the thermal conductivity parameters a geostatistical analysis of the available lithostratigraphic data was performed using the matlab toolbox modalstrata specially developed for this purpose a comprehensive geothermal subsurface characterization of calabria was thus obtained

a new correlation of the glacial moraines in the southern apennines italy abstract analysis of late pleistocene moraines in the southern apennines in southern italy suggests a possible correlation with the sequence in other italian regions but correlations with other parts of europe remain uncertain the lowest moraines consisting of complex loops recognized on the highest peaks in the southern apennines are attributable to the maximum of the last main glaciation with the subsequent rise in the snow line the glaciers retreated to new limits marked by two further stadial moraines the oldest and older dryas respectively which according to federici 1979 can be referred to the first and second apenninic stages the highest moraine loop which is present only on the pollino group may date from the lisens stage of the younger dryas

sediment generation in humid mediterranean setting grain size and source rock control on sediment geochemistry and mineralogy sila massif calabria abstract grain size control on sediment composition is investigated in modern proximal sediment from the sila massif where basic to felsic intrusive rocks are exposed in a mediterranean humid temperate upland climate samples were taken from small creeks and weathering profiles from three areas reflecting different bed rock compositions samples were separated into eleven grain size fractions from very coarse sand to clay and analyzed by i x ray fluorescence for chemical composition and ii x ray diffraction and mineral liberation analysis for mineralogical composition the chemical composition vs grain size relations were modeled by compositional linear regression mineralogical composition of selected samples is used to substantiate the interpretations based on geochemistry results reveal a high degree of chemical weathering with chemical index of alteration cia up to 92 high cia values are restricted to the fine grained fractions while sand sized sediment average at low to moderate cia values 60 although strongly weathered the three sample suites reflecting basic to felsic plutonic bed rock can be effectively discriminated across all grain size classes using trace elements such as v rb and sr linear trend modeling and mineralogical data reflect similar patterns for all sample suites implying similar processes independent of source rock composition this includes overall decrease of quartz and k feldspar over the full grain size range from very coarse sand to clay which is contrasted by overall increase of sheet silicates from coarse to fine among the latter increase of clay minerals strongly outpaces the increase of micas in silt to clay fractions a more complex behavior is shown by plagioclase which is most abundant in intermediate grain size fractions for all sample suites this is likely caused by initial hydrolysis along cleavage and twinning planes and subsequent breakage of plagioclase crystals into smaller fragments towards finer grain size intense hydrolysis has destroyed most feldspars

geomorphological study of the cafayate dune field northwest argentina during the last millennium abstract the cafayate depression is a dry valley located in the pre andean region of northwest argentina the area shows the development of a large dune field its significance has been established from geomorphological and mineralogical evidence grain shape characteristics and chronological data osl dating archaeological remains and historical data the dating results were between 1000 1100 ad to1740 1830 ad showing that the aeolian dynamics remained active during the last millennium it was not possible to identify stabilised phases marked by ruptures or paleosol development nevertheless other regional and local proxies from northwest argentina archaeological documentary etc were used to complete the interpretative framework to propose the paleoenvironmental evolution of the area in addition human activity and land use must be considered as a complementary factor affecting aeolian dynamics during the most recent stage