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

conditions and timing of incorporation of ophiolite into orogenic crust during oblique convergence central anatolia ophiolitic fragments scattered over a wide area of central anatolia exhibit varying degrees of metamorphism from unmetamorphosed to upper amphibolite facies although geochemical similarities suggest they are all part of the central anatolian ophiolite cao magmatic crystallization of oceanic crust in the cao at 91 ma coincided with high grade metamorphism of rocks that underlie the southern highest grade part of the cao raising questions about the tectonic relationship of the ophiolite to underlying metasedimentary and plutonic rocks new geochronology results show that the 40ar 39ar hornblende age of amphibolite facies metagabbro in the high grade metamorphic part of the cao is 87 ma similar to hornblende ages from amphibolite in the underlying nigde metamorphic plutonic massif biotite in a deformed quartzofeldspathic rock associated with high grade meta ophiolitic rocks yielded an 40ar 39ar age of 78 ma similar to biotite ages from the nigde massif hornblende in gabbro from unmetamorphosed cao yielded an older 40ar 39ar age of 90 ma similar to the previously determined crystallization age of the ophiolite these data indicate that the southern part of the ophiolite was incorporated into and therefore metamorphosed and deformed with the orogenic mid crust now exposed in the nigde metamorphic plutonic complex whereas the northern unmetamorphosed part of the ophiolite was obducted onto the continent this distinct difference in different parts of the ophiolite may indicate oblique collision or irregularities in the continental margin resulting in part of the ophiolite being incorporated into the orogenic crust and subsequently exhumed and cooled with it and another part being obducted

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

unravelling the development of a spheroidally weathered diorite gabbro santa margarita ecological reserve peninsular ranges southern california usa abstract within santa margarita ecological reserve smer southern california an 108 ma diorite gabbro pluton has weathered spheroidally resulting in the formation of concentric rindlets i e a rindlet zone around an unaltered ellipsoidal core of the parent rock to our knowledge little is known about how spheroidal weathering is produced in mediterranean climates like that characteristic of portions of the peninsular ranges hence we undertook a detailed study aimed at determining the textural and chemical changes associated with the spheroidal weathering of the diorite gabbro pluton the parental spheroidally weathered corestone is characterized by a hypidomorphic granular texture and consists primarily of plagioclase amphibole and biotite along with minor amounts of pyroxene and quartz within the corestone sericite and uncommonly calcite and chlorite replace plagioclase the latter mineral also infrequently replaces portions of amphibole and biotite such alteration products are derived from sub solidus deuteric alteration of the pluton xrd clay mineral analysis of the 13 rindlets indicates the presence of mostly kaolinite and vermiculite and a far lesser volume of green smectite thin section study of rindlet samples suggests that vermiculite is derived from the weathering of biotite the most extensively altered mineral in the rindlet zone such alteration is paralleled by statistically significant losses of k mass across the rindlet zone in addition statistically significant losses of ca and na mass across the rindlet zone likely reflect conversion of sericite to kaolinite in contrast the absence of statistically significant losses of mg fe and mn over most of the rindlet zone implies that fluids were mostly oxidizing and that any mg leached from amphibole was likely fixed within smectite while leached fe and mn precipitated out as oxides or oxyhydroxides though calcite was present in the corestone its absence in the rindlets indicates that fluids were sufficiently acidic to dissolve and remove it previous studies have shown that spheroidal weathering occurs when volume expansion produced by a positive v of reaction builds up internal elastic strain energy in the rock for example this type of reaction occurs when iron oxidizes within biotite resulting in an expansion of d 001 from 10 a to 10 5 a or when biotite is transformed into vermiculite leading to an expansion of d 001 from 10 a to 14 a data presented here suggest that the conversion of biotite to vermiculite and the resulting positive v produced the spheroidal fracturing of the corestone at smer hence these and other data discussed in this paper suggest that the weathering of biotite is the primary driving force in the formation of spheroidally weathered corestone in the mediterranean climate of the peninsular ranges

paleoclimate and extensional tectonics of short lived lacustrine environments lower cretaceous of the panormide southern tethyan carbonate platform nw sicily abstract subaerial erosion and continental sedimentation interbedded with shallow water carbonates are unequivocal stratigraphic records to evaluate paleoenvironmental and paleoclimate evolution of emerged landmass stratigraphic analysis of the cretaceous monte gallo section of the mesozoic panormide carbonate platform in the northern side of the palermo mountains nw sicily records a peculiar continental derived clays that interrupted the shallow water carbonate sedimentation these clays rest with lenticular geometries above the tectonically enhanced subaerial erosional unconformity of the barremian lower aptian requienid limestones and are covered by the upper cretaceous rudistid limestone sedimentological investigation combined with mineralogical and petrographic results reveal the occurrence of alkaline to saline lake clays deposition in pond filling depositional environment recording stressed conditions evaporation especially in its final living phase they were formed when a half graben tilted block tectonics produced footwall uplift of the gallo faulted blocks carbonate platform paleoclimate evaluations of the continental derived clays highlighted that a period of warm humid conditions which favoured their formation interrupted the uniform warm climate conditions highlighting a greenhouse climate phase

depositional systems composition and geochemistry of triassic rifted continental margin redbeds of the internal rif chain morocco the middle to upper triassic redbeds at the base of the ghomaride and internal dorsale calcaire nappes in the rifian sector of the maghrebian chain have been studied for their sedimentological petrographic mineralogical and chemical features redbeds lie unconformably on a variscan low grade metamorphic basement in a 300 m thick upward fining and thinning megasequence successions are composed of predominantly fluvial red sandstones with many intercalations of quartzose conglomerates in the lower part that pass upwards into fine grained micaceous siltstones and massive mudstones with some carbonate and evaporite beds this suite of sediments suggests that palaeoenvironments evolved from mostly arenaceous alluvial systems middle triassic to muddy flood and coastal plain deposits the successions are characterized by local carbonate and evaporite episodes in the late triassic the growth of carbonate platforms is related to the increasing subsidence norian rhaetian during the break up of pangea and the earliest stages of the western tethys opening carbonate platforms became widespread in the sinemurian sandstones are quartzose to quartzolithic in composition testifying a recycled orogenic provenance from low grade palaeozoic metasedimentary rocks palaeoweathering indices chemical index of alteration chemical index of weathering and plagioclase index of alteration suggest both a k enrichment during the burial history and a source area that experienced intense weathering and recycling processes these processes were favoured by seasonal climatic alternations characterized by hot episodically humid conditions with a prolonged dry season these climatic alternations produced illitization of silicate minerals iron oxidation and quartz rich red sediments in alluvial systems the estimated burial temperature for the continental redbeds is in the range of 100 to 160 c with lithostatic tectonic loading of ca 4 to 6 km these redbeds can be considered as regional petrofacies that mark the onset of the continental rift valley stage in the western pangea middle triassic before the opening of the western part of tethys in the middle jurassic the studied redbeds and the coeval redbeds of many alpine successions betic tellian and apenninic orogens show a quite similar history they identify a mesomediterranean continental block originating from the break up of pangea which then played an important role in the post triassic evolution of the western mediterranean region

lateral spreading phenomena and weathering processes from the tropea area calabria southern italy this paper describes the lateral spreading landslides the weathering processes and the hydrogeological risk patterns of the nw sector of monte poro calabria southern italy based on the development of a multidisciplinary research the tectonic uplift of the area combined with the litho structural features of the sedimentary deposits overlying the intensely weathered granitoid complex produces important gravitational phenomena characterized by lateral spreading kinematics the contact between deposits with a different behaviour together with the high slope energy related to the tectonic uplift processes is the main cause of widespread fracturing and disjoint of the lithologies associated with lateral spreading phenomena these phenomena are also testified by the various trenches and cracks characterized by a parallel orientation relatively to the main fluvial incisions measures of these deformations were obtained with a quantitative result by the use of interferometric stacking methods the experimental results confirm this morphological scenario characterized by strain values ranging between 20 and 25 mm year relatively to the landslides detected geomorphological analysis of the drainage basins in the study area indicates a juvenile stage of the stream networks this pattern is consistent with the high rate of tectonic uplift of the area hence the continuous rejuvenation of the stream networks and their low level of hierarchy these conditions of geomorphic equilibrium of the stream networks the widespread occurrence of geological instability in continuous evolution are the main causes of high hydrogeological risk conditions for this coastal area

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

metamorphism during alpine crustal thickening and extension in central anatolia turkey the nigde metamorphic core complex the nig de massif a metamorphic core complex in central anatolia high temperature reactions can obliterate assemblages turkey contains petrologic evidence for the transition from alpine formed during earlier lower temperature phases of meta crustal thickening to extension and exhumation of high grade mid morphism this can hinder use of petrologic information crustal rocks sillimanite potassium feldspar gneiss formed and to interpret tectonic processes if reaction textures are partially melted during barrovian metamorphism and records max preserved however rocks may record a range of pres imum conditions of 5 6 kbar 700 c the two mica uckapili sure temperature conditions from their prograde and granite and a related dike suite intruded the migmatitic metapelitic or retrograde paths and a more complete picture of the rocks forming a contact aureole that contains andalusite and tectonic evolution of a terrane can be reconstructed of cordierite these low pressure minerals indicate that crustal thick particular interest are the mechanisms and timing of ening was followed by exhumation of mid crustal rocks to relatively transition from contraction to extension and the ac shallow depths 10 km at lower temperatures before the em companying exhumation of middle to lower crustal placement of granitic magma formation of andalusite was followed rocks the present study describes a medium pressure by a second prograde episode of sillimanite growth during low high temperature terrane the nig de massif fig 1 in pressure high temperature metamorphism in the central part of the central anatolia turkey that developed as a meta massif where magmatism was most extensive a generalized p t morphic core complex in response to alpine crustal path for the highest grade rocks therefore consists of an initial thickening metamorphic rocks in the central high grade clockwise path with a late thermal spike and characterizes burial part of the massif record in their mineral assemblages and subsequent exhumation accompanied by magmatism reaction textures and structures the processes of burial exhumation and accompanying magmatism

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

the origin of brown hornblende in the artfjallet gabbro and dolerites brown hornblende occurs in minor amounts in the artfjallet gabbro and dolerites except in quartz dolerites where a pale green hornblende occurs in the gabbro brown hornblende is mostly ti bearing pargasite or kaersutite it occurs along veins of orthopyroxene as rims around and blebs in pyroxenes with orthopyroxene in coronas between olivine and plagioclase and in coronas between ilmenite and plagioclase in the olivine dolerites and orthopyroxene dolerites brown hornblende is ferroan titanian pargasite or ferroan kaersutite the pale green hornblende in the quartz dolerites is a magnesio hornblende the hornblendes in the dolerites are interstitial or granular in some dolerites occurring as coarse oikocrysts it is proposed that under certain conditions the ti content of hornblende can be used as a thermometer derived from experimental data of helz 1973 microstructures compositions and formation temperatures 1 040 c show that the brown hornblende in the gabbro is not magmatic but of subsolidus origin probably it formed as a result of the introduction of water into the gabbro during a deformation event that occurred early in the cooling history of the gabbro least squares modelling of hornblende formation indicates that all magmatic minerals must have participated in the reaction and that the reaction probably was not isochemical microstructures compositions and formation temperatures 1 030 965 c of brown hornblende in the dolerites are consistent with late stage crystallization from the magma for the pale green hornblende in the quartz dolerites a magmatic origin is likely but cannot be proven

chemical weathering of crystalline rocks in contrasting climatic conditions using geochemical proxies an overview abstract weathering profiles of granitoid rocks from the sila massif southern italy have been studied to characterize weathering processes that affect this area chemical weathering indices of the sila massif weathered granitoids were compared to those of different areas of the world characterized by different climates malaysia puerto rico georgia china nigeria colorado switzerland and sweden to decipher their weathering characteristics the geochemical indices show values of cia chemical index of alteration ranging from 55 to 97 ciw chemical index of weathering ranging from 60 to 100 pia plagioclase index of alteration ranging from 55 to 100 wip weathering index of parker ranging from 7 to 64 and rr ruxton ratio ranging from 2 14 to 3 96 all these geochemical proxies closely resemble each other and show variations mainly related to the different climatic and tectonic settings malaysia and puerto rico granitoids showing high cia values respectively 97 and 95 on average underwent very intensive chemical weathering alteration georgia china and nigeria showing medium high cia values respectively 86 90 and 92 on average underwent moderate intensive chemical weathering alteration southern italy and colorado granitoids showing medium low cia values 68 on average underwent moderate weak chemical weathering alteration whereas switzerland and sweden granitoids showing low cia values respectively 58 and 55 on average underwent weak chemical weathering alteration those values are mainly related to the climatic conditions in term of temperature and precipitation of each area cia vs climate histograms display a shift towards higher cia values with increasing of warm humidity tropical conditions whereas granitoids weathered under conditions inferred to be cold arid polar climate show lower cia values

geochemical character and tectonic environment of neotethyan ophiolitic fragments and metabasites in the central anatolian crystalline complex turkey

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

relative alteration of microcline and sodic plagioclase in semi arid and humid climates abstract petrographic determination of the degree of alteration of holocene detrital feldspars from first order streams indicates that a broad overlap exists in the amount of alteration on detrital feldspars from contrasting wet and dry climates thus the amount of alteration of detrital feldspars from ancient sandstones is probably an invalid indicator of paleoclimate furthermore regardless of climate detrital plagioclase ab 80 95 generally is 15 20 percent more altered than potassium feldspar in light of this the paleoclimatic significance of the observed relation potassium feldspar more weathered than plagioclase in ancient sandstones todd 1968 needs re evaluation results of this study do suggest a possible preference of limonite plus kaolinite on detrital feldspars from humid climates versus limonite plus smectite on feldspars from semi arid climates however unequivocal substantiation of this difference is still lacking even if the compositional difference can be rigorously demonstrated an inability to distinguish diagenetic from climate controlled surface weathering induced alteration of feldspar will further decrease the utility of feldspar alteration relationships in paleoclimate interpretation

a link between reduced barents kara sea ice and cold winter extremes over northern continents the recent overall northern hemisphere warming was accompanied by several severe northern continental winters as for example extremely cold winter 2005 2006 in europe and northern asia here we show that anomalous decrease of wintertime sea ice concentration in the barents kara b k seas could bring about extreme cold events like winter 2005 2006 our simulations with the echam5 general circulation model demonstrate that lower troposphere heating over the b k seas in the eastern arctic caused by the sea ice reduction may result in strong anti cyclonic anomaly over the polar ocean and anomalous easterly advection over northern continents this causes a continental scale winter cooling reaching 1 5 c with more than three times increased probability of cold winter extremes over large areas including europe our results imply that several recent severe winters do not conflict the global warming picture but rather supplement it being in qualitative agreement with the simulated large scale atmospheric circulation realignment furthermore our results suggest that high latitude atmospheric circulation response to the b k sea ice decrease is highly nonlinear and characterized by transition from anomalous cyclonic circulation to anticyclonic one and then again back to cyclonic type of circulation as the b k sea ice concentration gradually reduces from 100 to ice free conditions we present a conceptual model which may explain the nonlinear local atmospheric response in the b k seas region by counter play between convection over the surface heat source and baroclinic effect due to modified temperature gradients in the vicinity of the heating area

silt production as a function of climate and lithology under simulated comminution production of the silt sized particles composing loess represents a critical step in its ultimate formation but the volume and rate of production in different settings remain underdetermined this study addresses the influence of climate and source lithology on silt formation by subjecting natural alluvial fluvial sand from systems characterized by varying climatic setting to simulated comminution bulk samples from comparable transport distances were collected from a hot arid california desert alluvial system hot humid puerto rico fluvial system and cold humid norway proglacial fluvial system and sieved to isolate the coarse very coarse sand fraction for experimental milling source rocks in all three systems consist of granitoids with some contributions from foliated coarse grained metamorphic rocks gneissic and schistose in norway results indicate that contributions from coarse grained foliated lithologies impart a negligible effect on rate of silt production from the sand starting material climatic setting imparts no significant difference on sand durability but influences clay production at later stages of comminution for the puerto rico sample presumably owing to the effects of deep chemical weathering prior to physical transport comminution and silt production in all experiments exhibit exponential decay wherein rapid initial rates diminish with time this is interpreted to reflect the effects of the dynamic milling conditions particle size and distribution and slurry viscosity as well as particle strength with the latter including both relative strengths of different minerals in general and the influences of lattice defects and microfractures in quartz in particular empirical observations reveal that silt fractions of the natural alluvial fluvial samples collected at comparable transport distances 5 7 km in the respective systems exhibit significant differences bulk sediment samples from the norwegian proglacial system contain substantially more silt 3 10 times than either of the other two localities implying a significant difference in the natural processes operating to generate silt in these different field settings we suggest this difference reflects the efficacy of glacial grinding in silt production

decadal climate oscillations in the arctic a new feedback loop for atmosphere ice ocean interactions a combined complex empirical orthogonal function analysis of 40 years of annual sea ice concentration sic and winter sea level pressure slp data reveals the existence of an approximately 10 year climate cycle in the arctic and subarctic the cycle is characterized by a clockwise propagating signal in the sic anomalies and a standing oscillation in the slp anomalies the latter being linked to a fluctuation between the two phases of the north atlantic oscillation to describe the formation and evolution of the sic and slp anomalies associated with the cycle a simple feedback loop is proposed

the effects of source rocks and chemical weathering on the petrogenesis of siliciclastic sand from the neto river calabria italy implications for provenance studies plutonic and gneissic rocks of the sila massif in the uppermost portion of the neto drainage basin calabria southern italy weather and erode under a humid mediterranean climate during the development of weathering profiles a combination of chemical weathering and granular disintegration processes occurred chemical weathering involves a loss of both plagioclase mainly during grus generation and k feldspar mainly during soil formation this loss is attributed to transformation of plagioclase to clay minerals and to leaching and dissolution of k feldspar sand composition is quartzofeldspathic and nearly homogeneous along the main channel of the neto river even where the river cuts across a blanket of sedimentary cover thus fluvial transport does not alter sand composition within the neto drainage basin petrographic indices are effective in 1 discriminating between contributions from similar granite and gneiss source rocks qm f 2 relating the provenance of plutoniclastic and gneissiclastic sand found in the headwaters to grus horizons qm f q rg and 3 distinguishing between upstream first cycle and downstream multicycle sand q rg this last distinction is further emphasized by considering both aphanitic and phaneritic varieties of rock fragments rgrmrs diagram chemical weathering is the main sand producer within the regolithic environment in northern calabria in addition rapid erosion resulting from steep slopes removes weathered products and rapid and short transport leads to minimal sediment maturation in general the f q index is climate and relief dependent thus it should be used in conjunction with palaeoclimatic and palaeophysiographic evidence for provenance interpretations of ancient quartzofeldspathic sandstones

40ar 39ar and rb sr geochronology of high pressure metamorphism and exhumation history of the tavsanli zone nw turkey geochronological investigations in high and ultra high pressure metamorphic rocks are problematic since firstly the low temperatures lead to fine grain size and disequilibrium assemblages and secondly the problem of excess argon affects 40ar 39ar systematics the most commonly used isotopic system the tavsanli zone is a belt of high pressure low temperature hp lt rocks spanning nw turkey and is one such region where previous geochronological studies have produced a range of estimates for the age of hp lt metamorphism raising the question of whether they are geologically significant this study presents new data from the tavsanli zone 40ar 39ar ages are in the range 60 ma to 175 ma whilst rb sr ages are restricted to 79 7 ma to 82 8 ma confirming the presence of excess argon detailed ultra violet laser ablation microprobe uvlamp studies have revealed younger 40ar 39ar ages in the cores of coarser white micas which in conjunction with 40ar 39ar ages from the finest grained lithologies and the rb sr white mica crystallisation ages constrain the post hp lt metamorphism exhumation rates of these rocks petrological and regional constraints suggest that syn subduction exhumation and cooling took place initially by synchronous subduction and exhumation by underplating this is followed by a phase of syn continent continent collision at a rate of approximately 1 5 mma 1 and exhumation to the surface via thrusting the 40ar 39ar hornblende data from a granodiorite intruding the hp lt rocks constrain the later parts of exhumation path this study highlights the importance of a multi system geochronological approach when attempting to determine the history of hp lt rocks

geotechnical and landslide aspects in weathered granitoid rock masses serre massif southern calabria italy abstract the weathering processes produce important chemical and physical transformations in rock masses producing a decay of their strength and then stability in this study different methodologies were employed to define the physical mechanical properties and the minero petrographical changes at each grade of weathering useful to determine a geological model of the weathered granitoids involved in mass movements the paper focuses on a multidisciplinary research on the weathering profiles of the paleozoic granitoid rocks surrounding the village of fabrizia located in the serre massif southern calabria italy fabrizia lies on an old erosion surface composed of basement rocks made up of weathered granitoids belonging to the serre massif granitoid complex and overlain by thin eluvial colluvial deposits the tectonic uplift of the area combined with mediterranean climatic conditions both active at least since the quaternary are the main causes of the deep weathering of the plutonic rocks the weathered profiles of the granitoid complex have been studied through field observations borehole explorations with geotechnical tests and seismic surveys coupled to minero petrographical analysis and laboratory tests weathered profiles are mainly composed by rock masses varying from completely weathered and residual soil classes v vi to moderately weathered rocks class iii characterized by a progressive increase of geotechnical properties e g seismic wave velocity rock quality designation internal friction angle uniaxial compressive strength with a decrease of weathering the weathered rocks display a wide variety of mass movement landslide types are rockfalls for the fresher rocks class iii translational slides occur between different weathering degrees classes iv and v and rotational slides dominate at the top of the slopes and generally involve the weathering grades from class iv to classes v vi the shallow horizons are composed of thin eluvial colluvial deposits and more weathered granitoids classes v vi that may generate dangerous debris flows or debris avalanches during intense and prolonged rainfall the landslide surface is usually at a depth lower than 2 m in the debris flow type while deeper landslides depth 2 m are rotational and translational types with sliding surfaces occurring mainly in the transition between the classes iv and v the field survey coupled to geotechnical geophysical and minero petrographical data allowed the recognition of the different weathered horizons and relative geotechnical properties useful to the reconstruction of the reliable geological model the model represents an important support for the study of the landslide processes and for a sustainable management of the territory the used approach provided results to set a general reference framework for establishing more precise correlations between mass movement phenomena and weathering processes

mineral alteration and genesis of al rich soils derived from conglomerate deposits in cabo basin ne brazil abstract in the cabo basin ne brazil conglomerates have given rise to soils with attributes that are rarely observed in humid tropical climates and remain relatively unknown within the scientific community these soils have high levels of al in the exchangeable phase diminishing their agricultural and environmental potential in an underdeveloped region of great socioeconomic importance this paper presents the mineralogy and genesis of soils derived from conglomerates on a slope in the cabo basin with the aim of meeting the demand for studies on al rich soils three soils were classified morphologically described and sampled for the accomplishment of chemical physical and mineralogical analyses including the main exchangeable cations content mineralogy of the sand silt and clay fraction differentiation of the fe and al forms mineral micromorphology and chemical composition of mineral species in addition chemical and physical attributes were used in multivariate analyses the soil mineralogy is associated with the weathering evolution of three mineralogical zones identified in the cr horizons pathways of alteration followed by feldspars and micas resulted in kaolinite smectite and hydroxy al interlayered smectite formation argilification the susceptibility of the conglomerate to weathering constant releases of al from the structure of aluminous minerals low contents of exchangeable bases and consequent low ph values

impact of weathering on ree distribution in soil saprolite profiles developed on orthogneisses in borborema province ne brazil abstract rare earth elements rees are a group of elements from la to lu with high economic value and serve mainly as essential raw material for various high technology items this study explores mineral weathering and the geochemical evolution of regoliths quaternary period derived from orthogneisses late cretaceous period in four sites in borborema province ne brazil providing a new contribution to the understanding of the influence of soil and saprolite attributes on the distribution of rees in the regolith we used optical and electron microscopy to depict the weathering of minerals in the rock saprolite and soil microstructure focusing on the distribution of rees in the regolith depth 3 0 m we also determined the poorly and well crystallized iron oxide contents the clay fraction amount and the total organic carbon content to observe how these attributes influence the distribution of rees in the soil and saprolite the results allowed the classification of weathering for feldspars micas and other primary minerals into four stages based on their degree of alteration and the consequent influence on the geochemistry of the regoliths advancement of the weathering stages revealed the relative increases in fe and ti compared with ca mg na and k from the fresh rock up to the soil horizons and ilmenite and xenotime were the main sources of yb y co and p the patterns of signatures and anomalies were different for light lrees middle mrees and heavy rare earth elements hrees and for regoliths in different metamorphic complexes the lrees related well with the clay fraction amount the poorly crystallized iron oxides and the degree of weathering as estimated by the mineralogical index of alteration mia while the hrees related well with the total organic carbon toc in particular ce was strongly associated with mn oxides possibly due to simultaneous oxidative precipitation

characteristics of weathering zones of granitic rocks in malaysia for geotechnical engineering design tropical climatic conditions cause severe weathering to rock masses resulting in thick weathering profiles consisting of different weathering zones with complex characteristics feasible geotechnical engineering design requires a detailed understanding of the characteristics of each weathering zone a typical weathering profile is usually characterized by field scale observation and geological study this paper presents the characteristics of weathering zones of various granitic rocks in the south of malaysia this region has a tropical climatic condition the study was carried out in four active quarries located in johor province malaysia and forty sections were investigated in the study areas a typical granitic weathering profile was characterized based on the geological and structural parameters i e joint characteristics corestone occurrence rock soil ratio mass homogeneity color of rock and discoloration at joints surfaces the profile includes common zones ranging from fresh to residual soil however two subzones are introduced based on corestone boulder occurrence in the highly weathered and completely weathered zones this study based on detailed field observations at the mentioned quarries followed by analysis presents an amalgamated picture of weathering zones in granitic profiles of a tropical region like malaysia moreover it is believed that the characterization of the typical weathering profile allows further classification of generally complex weathered rock masses for a specific geotechnical engineering design

weathering processes of the dolomite in shibing guizhou and formation of collapse and stone peaks the dolomite in the yuntai mountain shibing guizhou china constitutes the gentle stratum affected by several weathering processes it is coupled with a vertical joint development which makes it easy to form the collapse and stone peaks corroded by running water the aim of this paper is to study the effects of weathering processes of dolomite outcropping in the yuntai mountain shibing guizhou china this work shows the dolomite s physical and mechanical characteristics microscopic characteristics of rock and pore structure based on chemical and minero petrographic analyses the findings indicate that the dolomite in this region is gray pure quality and hard packed superfine grain to fine grain mass surface voids suggest that the dolomite s pass is small and has more pore throat its grain cementation is relatively poor the degree of rock weathering is relatively high the mechanical strength is lower than that of the surrounding limestone this work shows how the macro micro characteristics of the dolomite affect the formation of collapse and stone peaks this work further focuses on the study of the cone shaped peak cluster basement and the upper tower shaped stone peaks which are the most important features of this region

counterclockwise p t t trajectory from the metamorphic sole of a neo tethyan ophiolite turkey abstract the kiziltepe ophiolitic thrust sheet in the bolkar mountains of turkey occurs between two subparallel ophiolite belts bounding the tauride carbonate platform and represents a remnant of the cretaceous neo tethyan oceanic lithosphere it is underlain by foliated amphibolite that represents a metamorphic sole developed at the inception of an intra oceanic subduction zone in the neo tethys 92 90 ma blueschist facies overprinting of the amphibolite indicates that the metamorphic sole was dragged deeper into the subduction zone where it experienced increasing p t with cooling regional tectonic constraints suggest a maastrichtian age for the timing of this blueschist facies metamorphism sodic amphibole rich veins and crossite mg riebeckite rims on hornblende suggest that growth of blueschist facies minerals was facilitated by infiltration of fluid along fractures and grain boundaries we infer a counterclockwise p t t trajectory during which metamorphism was accompanied succeeded by rapid uplift along the northern edge of the tauride belt in late cretaceous early tertiary time

sea ice anomalies observed in the greenland and labrador seas during 1901 1984 and their relation to an interdecadal arctic climate cycle two independent ice data sets from the greenland and labrador seas have been analyzed for the purpose of characterizing interannual and decadal time scale sea ice extent anomalies during this century sea ice concentration data for the 1953 1984 period revealed the presence of a large positive anomaly in the greenland sea during the 1960s which coincided with the great salinity anomaly an upper ocean low salinity water mass that was observed to travel cyclonically around the northern north atlantic during 1968 1982 this ice anomaly as well as several smaller ones propagated into the labrador sea and then across to the labrador and east newfoundland coast over a period of 3 to 5 years a complex empirical orthogonal function analysis of the same data also confirmed this propagation phenomenon an inverse relation between sea ice and salinity anomalies in the greenland labrador sea region was also generally found an analysis of spring and summer ice limit data obtained from danish meteorological institute charts for the period 1901 1956 indicated the presence of heavy ice conditions i e positive ice anomalies in the greenland sea during 1902 1920 and in the late 1940s and generally negative ice anomalies during the 1920s and 1930s only limited evidence of the propagation of greenland sea ice anomalies into the labrador sea was observed however probably because the data were from the ice melt seasons on the other hand several large ice anomalies in the greenland sea occurred 2 3 years after large runoffs in the early 1930s and the late 1940s from northern canada into the western arctic ocean similarly a large runoff into the arctic during 1964 1966 preceded the large greenland sea ice anomaly of the 1960s these facts together with recent evidence of climatic jumps in the northern hemisphere tropospheric circulation suggest the existence of an interdecadal self sustained climate cycle in the arctic in the greenland sea this cycle is characterized by a state of large sea ice extent overlying an upper layer of cool relatively fresh water that does not convectively overturn which alternates every 10 15 years with a state of small sea ice extent and relatively warm saline surface water that frequently overturns

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

weathering or hydrothermal alteration summary altered granites are sometimes attributed to deep weathering and sometimes to hydrothermal alteration the nature of the evidence for the latter is discussed and found inadequate in many instances the alteration at bega australia and dartmoor england is considered to result from deep weathering

provenance of mesozoic to cenozoic circum mediterranean sandstones in relation to tectonic setting abstract the composition and stratigraphic relations of clastic strata in diverse sedimentary basins of the circum mediterranean region reflect a complete record of provenance relations since break up of pangea neo tethyan taphrogenesis and subsequent plate convergence between the two major plates of europe and africa and other related microplates of iberia adria mesomediterranean and toward to the eastern mediterranean the anatolian microplate since plate reorganization after the breakup of pangea at the end of paleozoic earliest mesozoic clastic wedges filled sedimentary basins within geodynamic settings evolving from intracontinental rifts rifted continental margins protoceanic basins arc trench basin systems remnant ocean basins foreland basin systems and intramontane and back arc basins within the circum mediterranean region the changing nature of clastic particles in these clastic wedges reflect the provenance relations from different source rocks within the spatial and temporal evolving geo puzzle terranes including relations between ophiolite bearing uplifted continental crust both shallow to deep crust terranes volcanic and sedimentary particularly carbonate strata source rocks mixed siliciclastic and carbonate shallow to deep marine clastic wedges are diffuse in many filled basin systems along the mediterranean as such as occurrence of volcaniclastic layers interbedded with siliciclastic wedges the variable mosaic of source terranes within the mediterranean region offered the possibility to investigate provenance relations with a new plane of precision and sophistication discriminating grain particles in clastic wedges using spatial extrabasinal versus intrabasinal and temporal coeval versus noncoeval distinction of detrital signals the spatial temporal approach in deciphering particles in clastic rocks has been widely used to detail the basinal dispersal pathways in different geotectonic settings wherever mixed silicate and carbonate terranes act as the major source rocks from rifted continental margins to collisional orogens

significant enrichment of ga rb cs rees and y in the jurassic no 6 coal in the iqe coalfield northern qaidam basin china a hidden gem abstract this paper presents new data concerning the mineralogy and trace element geochemistry of the enriched rare metals in the jurassic no 6 coal from the iqe coalfield qaidam basin china the conclusions of this study are based on new data and evidence that suggest the considerable enrichment of ga rb cs rees and y in the no 6 coal of the iqe coalfield may be a hidden treasure with yet to be realized additional economic potential if such rare metal enrichment is proven across the whole area of iqe coalfield the no 6 coal is enriched in al 2 o 3 sio 2 na 2 o mgo p 2 o 5 k 2 o tio 2 rb cs ga sc v cr cu ba w pb th and rey especially in ga rb cs and h rey compared to world coals the average contents of ga cs rb and rey are 3 1 12 3 6 0 and 3 5 times higher than those of world bituminous coals respectively ga may occur in clay minerals e g kaolinite particularly in k rich clay minerals e g illite which are thought to be derived from the qilian mountain range these minerals are probably the hosting phases for both rb and cs in the coal studied rees and y in the coal are more likely to be associated with phosphates the combustion products e g fly and bottom ash derived from those coals may be further enriched in these valuable rare metals and have economic potential in terms of the recovery of ga rb cs rees and y providing additional economic value to this coal deposit

interpreting provenance relations from sandstone detrital modes southern italy foreland region stratigraphic record of the miocene tectonic evolution abstract the southern italy orogen preserves deep marine turbitic clastic wedges that record the key tectonic events during structural growing over the adria margin the regional tectonic transition from thick skinned calabrian accretion and deformation during late paleogene to middle miocene to thin skinned southern apennines thrusting since early middle miocene is recorded by diverse contrasting petrofacies in uppermost paleogene and miocene sandstones of dominantly turbiditie deposits most of these sandstones reflect in time quartzolithic and quartzofeldspathic and arkosic petrofacies derived from growing and unroofing calabrian terranes quartzose petrofacies mainly indicate provenance from cratonal african margin during langhian and or from lowland internal domains before its deformation during the cretaceous to paleogene volcaniclastic sandstone petrofacies also testify active volcanism during the late paleogene to early miocene these variable compositions indicate strong palaeogeographic constraints for the central western mediterranean during the neogene reflecting provenance relationships from differentiate source rocks these include interplays between ophiolitiferous uplifted continental shallow to deep crust terranes volcanic and sedimentary mostly carbonate source rocks sandstone detrital modes provide an example of the close relations between clastic compositions and growing orogen in southern italy and may contribute to unravel the geodynamic history of other major orogens

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

influence of low arctic sea ice minima on anomalously cold eurasian winters 1 influence of low arctic sea ice minima in early autumn on the wintertime climate over eurasia is investigated observational evidence shows that significant cold anomalies over the far east in early winter and zonally elongated cold anomalies from europe to far east in late winter are associated with the decrease of the arctic sea ice cover in the preceding summer to autumn seasons results from numerical experiments using an atmospheric general circulation model support these notions the remote response in early winter is regarded as a stationary rossby wave generated thermally through an anomalous turbulent heat fluxes as a result of anomalous ice cover over the barents kara seas in late autumn which tends to induce an amplification of the siberian high causing colder conditions over the far east the late winter cold anomalies over eurasia are also reproduced in our experiment which is associated with the negative phase of the north atlantic oscillation

tectonic controls on metamorphism partial melting and intrusion timing and duration of regional metamorphism and magmatism in the nigde massif turkey protracted heating and melting of orogenic middle crust followed by emplacement of a syn extensional pluton during decompression and cooling are demonstrated for a metamorphic core complex in central turkey new geochronologic data for the nigde massif of the central anatolian crystalline complex document an interval of melting crystallization and pb loss at elevated ambient temperature 85 92 ma determined by u pb shrimp within a single sample of peraluminous granite crustal melting was syn to post peak metamorphism 725 c dated at 91 0 2 0 ma by shrimp analysis of zircon rims in sillimanite schist that is part of the country rock to the pluton metamorphic monazite in sillimanite schist yields a younger age of 84 7 0 7 ma for matrix grains and inclusions in garnet hornblende 40ar 39ar ages from amphibolites interlayered with the sillimanite schists coincide with the timing of emplacement of magma into metamorphic country rock that had experienced cooling and decompression to 12 km and 550 c the similarity of 40ar 39ar ages for biotite in the pluton 79 ma and hornblende 79 81 ma biotite 74 76 ma and muscovite 78 83 ma in the metamorphic country rock document rapid cooling 100 c my following intrusion the coincidence of the youngest u pb magmatic zircon ages and the oldest 40ar 39ar ages combined with structural evidence for normal sense shearing and tectonic unroofing in the late cretaceous suggests that intrusion was driven by extension we propose that crustal melting occurred in the middle crust during prograde metamorphism and or initial decompression and that ascent and emplacement of magma as a pluton were only triggered once extension occurred and removed upper crustal rocks

lithological controls on hillslope sediment supply insights from landslide activity and grain size distributions the volumes rates and grain size distributions of sediment supplied from hillslopes represent the initial input of sediment delivered from upland areas and propagated through sediment routing systems moreover hillslope sediment supply has a significant impact on landscape response time to tectonic and climatic perturbations however there are very few detailed field studies characterising hillslope sediment supply as a function of lithology and delivery process here we present new empirical data from tectonically active areas in southern italy that quantifies how lithology and rock strength control the landslide fluxes and grain size distributions supplied from hillslopes landslides are the major source of hillslope sediment supply in this area and our inventory of 2800 landslides reveals that landslide sediment flux is dominated by small shallow landslides we find that lithology and rock strength modulate the abundance of steep slopes and landslides and the distribution of landslide sizes outcrop scale rock strength also controls the grain sizes supplied by bedrock weathering and influences the degree of coarsening of landslide supply with respect to weathering supply finally we show that hillslope sediment supply largely determines the grain sizes of fluvial export from catchments and that catchments with greater long term landslide rates deliver coarser material therefore our results demonstrate a dual control of lithology on hillslope sediment supply by modulating both the sediment fluxes from landslides and the grain sizes supplied by hillslopes to the fluvial system

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

core complex development in central anatolia turkey tectonic models for the central anatolian segment of the alpine himalayan orogen have not considered this region as part of the aegean extensional province we have found evidence however for oligocene miocene extension and exhumation of midcrustal rocks in a metamorphic dome nigde massif that is structurally and petrologically similar to miocene core complexes 500 km to the west strong correspondence in the timing and kinematic development of the menderes western turkey and nigde core complexes suggests that extensional tectonics and exhumation of mid to lower crustal rocks affected much of the eastern mediterranean region in the nigde massif supracrustal rocks were buried to depths of 16 20 km at high temperatures 700 c during contraction associated with closure of neo tethyan seaways in late mesozoic early cenozoic time following cooling and decompression to 600 c and 10 km metasedimentary rocks underwent a second heating event at low pressures during miocene magmatism that postdated much of the unroofing of the massif development of the nigde core complex was related to exhumation of thickened and thermally weakened continental crust in the upper plate of a north dipping subduction zone the partial subduction of the tauride carbonate platform in the eocene resulted in choking of the subduction zone followed by isostatic rebound and exhumation of the buoyant platform this in turn caused a rapid emergence of the upper plate resulting in erosion of upper crustal rocks and exhumation of midcrustal rocks along the northern edge of the inner tauride suture zone although northern regions of central anatolia contain the same protoliths as the nigde massif and underwent extensive tertiary magmatism they did not undergo similar extension suggesting that core complex development in south central turkey was controlled by the location of thickened and thermally weakened crust adjacent to a suture zone

residual regolith derived from the biotite controlled weathering of cretaceous tonalite quartz diorite peninsular ranges southern california usa a case study abstract though k feldspar free tonalite and quartz diorite are common plutonic rocks in exhumed continental margin magmatic arc rocks around the globe how they weather has not been extensively studied we therefore undertook an investigation aimed at understanding how an approximately 6 m thick section of residual regolith saprock and overlying alfisol developed from cretaceous k feldspar free tonalite and quartz diorite at santa margarita ecological reserve southern california usa we analyzed three samples of soil 10 of saprock and 10 of corestone for their major trace and rare earth element compositions thin sections of each major textural group also were studied and point counted common xrd techniques were used to determine clay mineralogy three samples of soil and five of saprock were analyzed for their ph within the saprock an extensive network of cracks was likely produced by the volumetric expansion that accompanied the conversion of biotite to vermiculite migrating near neutral fluids responsible for this conversion resulted in a loss of k mass and affected several trace elements that are commonly found in biotite but with the exception of an interval between 177 and 270 cm left most other major trace and rare earth elements ree little affected within the 177 to 270 cm interval at a depth of 208 cm relative to the immobile framework incongruent leaching of plagioclase by acidic solutions resulted in the losses of si al ca na pb sr and ga mass in contrast more neutral solutions added heavy ree hree and y mass at 177 to 237 cm depths while acidic solutions removed ree and y mass at 270 cm depth in the soil acidic solutions attacked plagioclase biotite and apatite leaching and removing relative to the immobile framework ca na mg k and p mass in addition the dissolution of apatite resulted in depletions in hree and y mass none of the elemental mass removed from the soil accumulated in the directly underlying saprock and must have been removed from the near vertical plane of sampling within the saprock the above changes are mostly the result of near neutral ph water rock interactions occurring within a warm and dry holocene climate identified changes in elemental mass other than those associated with the conversion of biotite to vermiculite are localized and are likely the result of the paths taken by fluids with differing ph moving through the complex network of cracks any model purporting to describe the evolution of residual regolith must explain such natural complexities

winter weather patterns over northern eurasia and arctic sea ice loss abstractusing ncep ncar reanalysis and japanese 25 yr reanalysis jra 25 winter daily 1 december 28 february data for the period 1979 2012 this paper reveals the leading pattern of winter daily 850 hpa wind variability over northern eurasia from a dynamic perspective the results show that the leading pattern accounts for 18 of the total anomalous kinetic energy and consists of two subpatterns the dipole and the tripole wind patterns the dipole wind pattern does not exhibit any apparent trend the tripole wind pattern however has displayed significant trends since the late 1980s the negative phase of the tripole wind pattern corresponds to an anomalous anticyclone over northern eurasia during winter as well as two anomalous cyclones occurring over southern europe and in the mid to high latitudes of east asia these anomalous cyclones in turn lead to enhanced winter precipitation in these two regions as well as negative surface temperature anomalies over the mid to high latitudes of asia the

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

a case study of a precariously balanced rock its partially exhumed corestone platform and encasing saprock and soil abstract lying between the elsinore and san jacinto faults 0 5 km se of roundtop is a tonalitic corestone perched precariously on an exhumed corestone base such features are referred to as precariously balanced rocks pbrs cosmogenic 10be data listed in an online abstract suggest a tentative exhumation age of the pbr near roundtop at 35 000 years ago the absence of pbrs adjacent to the elsinore and san jacinto faults implies that they were shaken free from their perches during ground shaking alternatively their absence may reflect a more highly fractured and intensely weathered terrane because the weathering histories of pbrs have not been studied previously we analyzed the texture clay mineralogy and geochemistry of the roundtop pbr to answer several basic questions can the characteristics of the regolith that once encased the precariously balanced rock be reconstructed what chemical processes operated in the regolith prior to exhumation and are these processes still occurring following exhumation did new fracture development modify the original regolith to answer these questions we extracted three 1 m long cores from the pbr near roundtop and collected 23 saprock and 9 pebbly sandy loam samples from a trench excavated near the base of the corestone platform plagioclase and biotite alteration along with the concomitant loss of ca na sr ba k mg mn nb and p mass are the primary evidence of weathering intensity within the saprock additionally the presence of mostly kaolinite and lesser quantities of mixed layer biotite smectite in the saprock along with the above observations and data point to significant fluid rock interations during saprock development subsequent formation of pebbly sandy loam appears to have been accomplished primarily through pedoturbation within the uppermost portions of the underlying already weathered saprock and produced little additional chemical weathering hence our data support the general idea that roundtop is an area of weak ground shaking and that since current exhumation little weathering has affected this pbr locality

40ar 39ar geochronology of supergene k bearing sulfate minerals cenozoic continental weathering and its paleoclimatic significance in the tu ha basin northwestern china abstract 40ar 39ar incremental heating analyses of supergene jarosite and yavapaiite were conducted for three weathering profiles at the hongshan liuhuangshan and caihuagou deposits in the tu ha basin the analyses provide numerical constraints on the timing and duration of weathering and supergene enrichment well constrained plateau ages and best fitting inverse isochrons yield 40ar 39ar ages ranging from 33 3 0 5 ma to 3 3 0 4 ma 1 our 40ar 39ar ages combined with the published ages indicate that a protracted history of weathering and supergene enrichment and by inference arid semiarid climate with at least a moderate amount of precipitation 10 cm y favorable to intense chemical weathering emerged at 33 3 ma 27 7 23 3 ma and 16 4 14 7 ma and prevailed from 11 to 7 8 ma then a progressive change from arid semiarid toward hyperarid conditions and predominantly hyperarid conditions may have persisted since at least ca 3 3 ma the climatic implications inferred from the weathering geochronology are in agreement with the chemical parameters and isotopic compositions of the cenozoic sedimentary sequence from the lianmuqin section in the tu ha basin attesting to the reliability of weathering geochronology by the 40ar 39ar method as an indicator of paleoclimate in arid areas our results suggest that the retreat of the paratethys sea which would have reduced eastward water vapor transport by the westerlies to the tu ha basin led to its aridification in the oligocene and that increased rain shadow effects resulting from uplift of the tibetan plateau and tian shan mountains played important roles in the aridification history of the tu ha basin since the late miocene

mineralogy and geochemistry of various colored boles from the deccan volcanic province implications for paleoweathering and paleoenvironmental conditions abstract boles are markers of hiatus in successive eruptions of the deccan flood volcanism dfv emplaced at the cretaceous paleogene boundary that are interpreted to retain paleoenvironmental information from their subaerial exposure to evaluate paleoenvironment during these hiatuses mineralogy and geochemistry of three different colors of boles i e red dark 10r 3 6 and light 10r 4 8 brown 5yr 4 4 and green 5g 6 2 were examined the plagioclase index of alteration pia loss of ca and na relative to al was between 76 and 81 for all the boles indicating moderate chemical weathering that is probably due to their short subaerial exposures mass balance calculations show significant enrichments of k si mg and rb in green and brown boles suggesting an allochthonous input that is interpreted as volcanic ash fallout mineralogically the red bole is dominated by montmorillonite and hematite the brown bole of ferruginous smectite and montmorillonite and the green bole of celadonite and nontronite montmorillonite and hematite genesis in red boles indicates leaching in an oxidative environment at near neutral ph 5 5 to 8 conditions further heating of the altered basalt from emplacement of upper lava flows under subaerial dry conditions could have also promoted the formation of hematite in red boles the hydrothermal alteration of k and mg enriched volcanic ash admixed with the altered lower flow basalt under slightly reducing oxidation potential led to the genesis of nontronite and celadonite in the green bole the aluminous fe smectite in brown bole occurred from hydrothermal alteration of aluminous clays e g montmorillonite the different colored boles therefore suggest a range of weathering processes including chemical leaching to hydrothermal alteration in oxidative to reducing environmental conditions throughout dfv emplacement that could reflect changing surficial conditions associated with volcanically forced changes to the environment

timescales of migmatization melt crystallization and cooling in a cordilleran gneiss dome valhalla complex southeastern british columbia 1 integration of in situ and conventional ion microprobe u th pb zircon and monazite geochronology with 40ar 39ar hornblende biotite and muscovite thermochronology provides a temporal record of metamorphism partial melting fluids and cooling of exhumed midcrustal to lower crustal rocks the valhalla complex southeastern british columbia is one of a series of elongate gneiss domes within the omineca belt of the canadian cordillera we have performed u th pb and 40ar 39ar age measurements on migmatitic gneisses from a range of structural levels and settings within the valhalla complex in an effort to better document the timing of migmatization and exhumation stromatic migmatites and leucosomes crystallized in boudin necks yield concordant u pb zircon ages that cluster near 60 ma and th pb monazite ages of circa 60 50 ma in situ analyses of monazite in samples that contain 60 50 ma however the combined data also suggest that melt crystallization circa 60 ma in the valhalla complex occurred rapidly and before the other domes within the omineca belt cooling at 49 ma throughout the omineca is associated with regional extension and exhumation of migmatites in the domes the presence of abundant migmatites and the similarity in timing of melt crystallization and cooling in domes along the 400 km long omineca belt is consistent with localization of exhumation at the boundary between the flowing crust of the hinterland and the rigid colder crust of the rocky mountain foreland

crustal homogenization revealed by u pb zircon ages and hf isotope evidence from the late cretaceous granitoids of the agacoren intrusive suite central anatolia turkey geochemical and isotopic evidence from the agacoren igneous association in central anatolia turkey indicates that this suite of calc alkaline granitic rocks have undergone crustal homogenization during regional metamorphic and related magmatic events whole rock chemical and sr nd isotopic data of the granitoids reveal crustal affinity with an earlier subduction component zircons show inherited cores and subsequent magmatic overgrowths the laser ablation icp ms 206pb 238u zircon ages are determined as 84 1 1 0 ma for the biotite muscovite granite 82 3 0 8 1 1 ma for the hornblende biotite granite 79 1 2 1 1 5 ma for the granite porphyry dyke 75 0 1 0 1 0 ma for the alkali feldspar dyke and 73 6 0 4 ma for the monzonite this is interpreted as continuous magma generation possibly from heterogeneous sources from ca 84 to 74 ma during the closure of the northern branch of the neotethyan ocean the oldest granitoids 84 82 ma were probably formed due to crustal thickening after obduction of the morb type oceanic crust onto the tauride anatolide microplate the younger granitoids are interpreted to be related to the subsequent post collisional extension after lithospheric delamination combination of the laser ablation icp ms zircon lu hf isotope data with the u pb ages of inherited cores suggests that cretaceous granitoids formed by melting of heterogeneous crustal protoliths which results in significant variation in ehf t data from 12 9 to 2 2 these protoliths were probably composed of reworked early proterozoic crust minor juvenile late proterozoic magmatic components and paleozoic to pre late cretaceous recycled crustal material moreover the late cretaceous zircon domains of the different granitoids are characterized by a crustal signature with a relatively restricted zircon ehf t data ranging from 4 1 to 8 8 this variation is only about twice the reproducibility ca 1 ehf of the data but much smaller than the isotope variability of inherited zircons our preferred interpretation is effective isotopic homogenization of the heterogeneous central anatolian crust during the late cretaceous high grade metamorphic and magmatic events a process that we propose to be relevant for other active continental margins

weathering grade of rock masses as a predisposing factor to slope instabilities reconnaissance and control procedures weathering of rock masses often assumes importance as a predisposing factor to slope instability and it is possible to map it at various scales depending on the different purposes the effects of weathering processes are particularly intense on crystalline rocks plutonic and metamorphic these rocks are present in large areas of the globe and widespread in calabria the relationships between rock mass weathering grades and slope instabilities are analysed with reference to sectors 1 50 000 scale and areas 1 10 000 scale where crystalline rocks are strongly affected by weathering to this aim a reconnaissance procedure has been proposed to delimitate the zones with different weathering condition three macro classes at average scale 1 50 000 and six classes at detail scale 1 10 000 in this procedure first analysis of aerial photos and then field observations of representative situations have been used the reconnaissance procedure has been verified in a selected study area acri whose geological features are provided by the comparison with weathering maps obtained by means of a control procedure this last procedure consists of observations and index tests carried out in check points located in representative check sites discolouration sound when struck by geological hammer effect of the point of geological pick breaking with the hands rebound of schmidt hammer grain size analysis the results obtained confirm through quantitative data that the weathering of a rock mass can be assumed as a predisposing factor to slope instability at average scale 1 50 000 the reconnaissance procedure is able to give weathering maps representative for this type of evaluation the ratio between the landslides area in each weathering macro class and the whole landslide area goes from 67 to 14 for the macro class a and from 24 to 9 for the macro class b at detail scale 1 10 000 it is necessary to use a control procedure to obtain weathering maps indicative of predisposition to slope instabilities

metamorphism of the central anatolian crystalline complex turkey influence of orogen normal collision vs wrench dominated tectonics on p t t paths the central anatolian crystalline complex cacc is a microcontinent in the alpine himalayan belt it has previously been considered as a coherent structural entity but although the entire cacc is comprised of similar rocks primarily metasedimentary rocks and granitoids it consists of at least four tectonic blocks characterized by different p t t paths these blocks are the kirsehir north west akdag north east nigde south and aksaray west massifs the northern massifs experienced thrusting and folding during collision and were slowly exhumed by erosion metamorphic rocks are characterized by clockwise p t paths at moderate p t and local low p high t lp ht overprinting in the highest grade rocks apatite fission track ages are eocene to oligocene 47 32 ma the aksaray block represents the hot shallow mid crust of a late cretaceous early tertiary arc it is dominated by intrusions rare metapelitic rocks record low p 4 kbar regional metamorphism overprinted by lp ht contact metamorphism apatite fission track ages are 50 45 ma the nigde massif is different from the other cacc blocks because it evolved as a core complex in a wrench dominated setting it is characterized by clockwise p t paths at moderate p t followed by widespread lp ht metamorphism apatite fission track ages are miocene 12 9 ma significantly younger than those in the northern massifs nigde rocks resided in the mid crust at a time when the rest of the cacc was at or near the earth s surface variations in p t t and tectonic histories especially timing of exhumation between the northern and southern cacc reflect the difference between head on collision vs mid crustal wrenching

mineralogical and δ18o δd isotopic study of kaolinized micaschists at penestin armorican massif france new constraint in the kaolinization process abstract many kaolinite occurrences developed from paleozoic rocks forming the basement of the armorican massif in western france their origin hydrothermal alteration and or weathering is still discussed in order to provide new constraints to this debate we studied the kaolinite occurrence at penestin in the southern part of the armorican massif using several approaches including field and petrological observations mineralogical analyses xrd and stable oxygen hydrogen isotope analyses an alteration profile was developed from faulted micaschists showing from the bottom to the top of the profile a reddish saprolite zone with pure white kaolinite fissures cutting across the schistosity and a white kaolinite zone 5 10 m thick the detailed study by xrd of the layer silicates enabled us to characterize a mineralogical sequence with increasing alteration intensity which is coherent with a weathering evolution mica chlorite illite vermiculite chlorite mixed layer mineral vermiculite vermiculite kaolinite mixed layer mineral kaolinite moreover an intense iron leaching process occurs within the kaolinite zone which is characterized by a bleaching of this zone combined with iron oxyhydroxide precipitation along within fractures and cracks the isotopic analyses of kaolinite from the zone and fissures gave 18o values ranging from 19 64 to 21 21 and d values ranging from 69 4 to 65 8 this confirms that kaolinite was formed by low temperature water rock interactions in contact with meteoric fluids during weathering processes isotopic and stratigraphic data suggest that this weathering occurred before the messinian 7 ma and probably dates back to the eocene during which the climate was sub tropical at this location

landslide triggering scenarios in homogeneous geological contexts the area surrounding acri calabria italy abstract the paper describes a methodology to detect landslide triggering scenarios in geological homogeneous areas and for some specific landslide categories in these scenarios the rainfall landslide relationship as well as the pluviometric load conditions influencing slope instability have to be investigated the methodology is applied to an area located in northern calabria italy and affected by widespread and different slope instability phenomena outcropped fractured and deeply weathered crystalline rock masses determining geologic homogeneous conditions are present in the same area suitable and homogeneous climatic features have also been found according to the methodology adopted the hydrologic analysis of rainfall time series is initially carried out notwithstanding historical data concerning landslide mobilization but using simple models to determine critical pluviometric scenarios for the three landslide categories shallow medium deep and deep landslide triggering scenarios individualized according to this procedure are less significant as compared to the landslide mobilization detected in the study area by means of historical research and ascribed to the three landslide categories according to geomorphologic analysis subsequently the possible landslide triggering scenarios are outlined by carefully investigating the hydrologic analysis limited to the periods identified according to the historical data in the study area and approximately for all the areas characterized by the outcrop of fractured and deeply weathered crystalline rocks significant triggering scenarios can be outlined in particular shallow landslide triggers could be activated by rainfall events with intensities exceeding 90 mm day and or with amounts exceeding 160 mm as for medium deep and deep landslides triggering mechanisms are more complicated and effective rainfall contribution must be taken into account compared to groundwater storage moreover a more complex link between deep landslides and precipitation is confirmed the results obtained to date highlight the potential of this methodology which enables us to define and progressively improve the knowledge framework by means of a work sequence integrating different disciplinary tools and results

initial generation of sand across climate zones of the mojave sierra nevada and klamath batholiths in california u s a the generation of modern plutoniclastic sediment across california varies with climate resulting in significant mineralogical and geochemical differences between parent rock weathering profile material and low order stream sand with average precipitation of 15 cm yr in the arid zones and 120 cm yr in the temperate zones feldspar is relatively decreased in stream sand compared to parent rock by 2 and 20 respectively potassium feldspar is more resistant to weathering than plagioclase but is less stable than quartz in temperate climates hornblende and biotite are more easily weathered in temperate than arid climates although their occurrence in medium grained stream sands is affected by hydraulic sorting and comminution during transport temperate climate sands have lower concentrations of cao and na2o compared to k2o and al2o3 reflective of the expected faster loss of plagioclase than potassium feldspar during weathering with the exception of biotite the mineralogy of medium grained stream sand reflects that of medium grained weathering profile material in both climates confirming the findings from constant climate case studies that the composition of proximal sand is largely achieved within weathering profiles and during initial erosion we encourage continued attention to climate as a control on sand composition in provenance and paleoclimate studies where a moderate precipitation shift is capable of producing a significant loss of feldspar the differential response of common minerals to chemical weathering should be considered for studies and modeling related to bedrock erodibility sediment supply and landscape evolution

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

gneiss domes metamorphic core complexes and wrench zones thermal and structural evolution of the nigde massif central anatolia 1 the nigde massif a migmatite cored structural dome in south central turkey was metamorphosed deformed intruded and exhumed in an oblique tectonic regime involving a switch from transpression prograde metamorphism to transtension exhumation an 80 ma history of transpression and transtension is recorded in metamorphic rocks of the massif and the last 50 ma are recorded in both basement and overlying basin deposits nigde metamorphic rocks record a high temperature top to north syntranspression ductile fabric that was overprinted by lower grade top to south syntranstension ductile shear zones the 40ar 39ar data for hornblende muscovite and biotite document rapid late cretaceous cooling with the oldest ar hornblende ages 88 79 ma overlapping u pb ages in monazite and zircon 92 78 ma muscovite ar ages are dominantly 81 79 ma suggesting a short time between crystallization of high temperature metamorphic rocks and their cooling biotite ar ages are 79 74 ma with the exception of disturbed samples from the eastern margin of the massif and from eocene granitic stocks in the dome core the eastern margin adjacent to the sinistral central anatolian fault zone records another cycle of burial and exhumation that overprinted earlier fabrics and disturbed isotopic systems these two cycles of burial exhumation took place repeatedly along the same zone this may be characteristic of highly oblique tectonic regimes in the nigde massif burial and exhumation became more localized and of lower amplitude over time suggesting stabilization of the crust

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

dating subduction zone metamorphism with combined garnet and lawsonite lu hf geochronology studies of ancient and active subduction zones are critically important to understanding processes of interplate coupling crust mantle recycling and arc magmatism dating subduction metamorphism along prograde and retrograde paths in order to constrain such processes however has proved to be extremely difficult the complex thermal history of subduction systems poses significant challenges to low t geochronometers and subduction zone assemblages commonly lack suitable minerals for higher temperature geochronology garnet and lawsonite however are critical index minerals of high and low t subduction zone metamorphism and are well suited to lu hf geochronology in addition the closure temperature for lu hf in garnet and lawsonite should be sufficiently high that an age will date mineral crystallization and therefore the timing of subduction zone metamorphism the relative stability and timing of garnet and lawsonite formation will be controlled by the bulk composition peak metamorphic conditions and shape of the p t path experienced by a particular sample to test the influence of metamorphic conditions and p t path on lu hf geochronology garnet and lawsonite bearing samples were dated from rocks where lawsonite formed after garnet along a retrograde path stabilized prior to garnet along a prograde path and formed contemporaneously with garnet in the franciscan complex the ages of garnet epidote amphibolite garnet epidote blueschist garnet lawsonite blueschist and lawsonite blueschist range from c 166 130 ma and generally decrease with decreasing metamorphic grade consistent with previous studies garnet lawsonite blueschist eclogite formed along an apparent prograde path at ward creek records an apparent age of c 152 ma lower temperature lawsonite blueschist at ward creek however failed to provide a geologically significant date and likely reflects isotopic disequilibrium at low temperatures the apparent temperature time history from franciscan complex lu hf ages most likely reflects samples derived from various portions of the subduction zone or that were subducted and metamorphosed at different times in the thermal evolution of the subduction zone in the sivrihisar massif lawsonite eclogite and garnet lawsonite blueschist record distinctly different ages of 91 1 1 3 ma and 83 3 1 8 ma the different ages date the timing of high p metamorphism within each protolith and suggest that garnet lawsonite eclogite metamorphism pre dated garnet lawsonite blueschist metamorphism in these samples by c 8 ma the age of lawsonite eclogite metamorphism extends the timing of high p metamorphism and requires subduction initiation prior to 91 ma the results indicate that the lu hf system provides a reliable tool for dating the wide range in p t conditions of subduction zone metamorphism lawsonite dating in particular provides a reliable method by which to date low t retrograde and prograde metamorphism in the absence of garnet lawsonite may not be ideal for geochronology if sufficient garnet coexists in the mineral assemblage the lawsonite has very low t stability or if extremely fine grained hf phases such as zircon are present in lawsonite in poly metamorphic assemblages where the pressure and temperature can be estimated for separate garnet and lawsonite sub assemblages the age discrepancy between garnet and lawsonite may provide the ability to quantify the rates of heating or cooling and subduction or exhumation

sedimentology diagenesis and reservoir quality of the upper abu gabra formation sandstones in the fula sub basin muglad basin sudan abstract successful hydrocarbon exploration of the lower cretaceous abu gabra formation has established the need to understand the diagenesis and reservoir quality of the sandstones reservoirs in the area therefore this study contains a subsurface facies analysis based on description of three conventional cores from the moga21 2 well methods include wireline log analysis a petrographic study with both thin sections and scanning electron microscope investigations grain size x ray diffraction xrd and heavy minerals analysis of the abu gabra sandstone sedimentary composition and facies sequences of the well logs indicate a complex fluvial channel paleo environment grain size analysis revealed that the sandstone is a mixture of mainly sand size petrographically the sandstones are classified based on standard rock classification schemes into subfeldspathic arenites and feldspathic arenite lithofacies quartz grains are the most abundant detrital components in the samples both polycrystalline and monocrystalline followed by feldspars mainly k feldspar micas and detrital and authigenic clays with carbonatic detritus although lithic fragments iron oxides and heavy minerals occur in minor amounts presence of sillimanite epidote and hornblende compared to zircon tourmaline and rutile as well as the presence of chlorite the dominance of polycrystalline quartz and high crystallinity of kaolinite could be responsible for the low grade metamorphism kaolinite is an authigenic component while quartz overgrowths occur in variable quantity and carbonates calcite and siderite in a relatively minor amount pore types are basically primary and secondary interparticle with few secondary intraparticle pores due to the dissolution of feldspars although porosity ranges from 9 20 to 31 20 the presence of kaolinite carbonate and quartz overgrowth cement reduce the porosity of the samples analyzed samples are characterized by poor to very good pore interconnectivity despite the fact that most of the sandstones display point concavo convex and long contacts with poor to good compaction few sutured grain contacts which reflect a higher degree of compaction still exist xrd and sem analyses show that kaolinite chlorite illite smectite and illite smectite mixed layer clay are the common clay minerals in the studied samples the presence of vermiform morphology besides the sharp peak pattern of the kaolinite in most of the xrd pattern indicates that part of the kaolinite was authigenically formed

exhumation of blueschists along a tethyan suture in northwest turkey a blueschist belt formed during the mid cretaceous 88 ma high pressure metamorphism of a passive continental margin sequence of shale siltstone quartzite and limestone occurs immediately south of the tethyan suture in northwest turkey a transect across the tethyan suture was mapped to constrain the exhumation of blueschist facies assemblages the presence of jadeite glaucophane and lawsonite in the blueschists indicates p t conditions of 20 kbar and 430 c the blueschists are tectonically overlain by a cretaceous oceanic accretionary complex showing an incipient blueschist metamorphism a peridotite slab with subvertical layering lies along a low angle fault contact over the blueschists and the accretionary complex isolated slices of early cretaceous 101 4 ma garnet amphibolites occur at the base of the peridotite the garnet amphibolites which show an incipient blueschist facies overprint have probably formed during the oceanic subduction in the foot wall of the subduction zone and later underplated the hanging wall blueschists and peridotites are abruptly truncated in the north by the steeply dipping suture fault that juxtaposes unmetamorphosed and slightly deformed triassic to jurassic sediments of the northern continent against the peridotite and the accretionary complex tectonic juxtaposition of the lower pressure accretionary complex and peridotites over the higher pressure blueschists implies the removal of a 45 km thick oceanic mantle sequence above the blueschists regional geological and geometric constraints suggest that the exhumation of the blueschists was achieved by a combination of two simultaneously acting mechanisms the first was the detachment of the upper crustal blueschist sequence from its basement in the subduction zone and its incorporation to the hanging wall followed by buoyant ascent the second mechanism is the progressive shallowing of the subducted continental lithosphere resulting in the thinning of the mantle wedge above the subducted slab the blueschists were partly exposed prior to the paleocene continent continent collision post collisional eocene 52 48 ma calc alkaline plutons that were emplaced in the blueschists and the overlying peridotite at 10 km depth are interpreted to have formed by crustal anatexis from advective heating by mantle melts these have probably been generated during the upwelling of the asthenosphere under the shallowing continental lithosphere

characteristics and 40ar 39ar geochronology of the erdenet cu mo deposit mongolia the early to middle triassic erdenet porphyry cu mo deposit in northern mongolia developed in a continent continent arc collision zone within the central asian orogenic belt the porphyry system is related to multiple intrusions of crystal crowded biotite granodiorite porphyry which formed a composite stock about 900 m in diameter with multiple porphyritic microgranodiorite dikes wall rocks are late permian to early triassic medium grained granodiorite with similar whole rock geochemistry mineralogy and composition to the granodiorite porphyry whole rock analysis of the granodiorite porphyry and wall rocks shows that these rocks cannot be discriminated but both have depleted middle heavy rare earth elements and y typical of fertile porphyry magmatic suites at the current pit level 1 250 m elev early porphyry style quartz veins a and b type are locally infilled by pyrite chalcopyrite with subordinate bornite but most of the chalcopyrite occurs in d veins that constitute more than 50 of the cu grade 0 5 wt cu the 0 3 wt cu shell resembles a molar tooth enveloping the granodiorite porphyry with deeper roots extending down the wal rock contacts molybdenite occurs in monomineralic veins and in finely laminated to massive quartz molybdenite veins the most important alteration is quartz muscovite which occurs as relatively coarse 100 500 m alteration selvages 1 5 cm that envelop d veins the d veins cut illite kaolinite smectite or intermediate argillic alteration intermediate argillic alteration together with abundant pink anhydrite commonly hydrated to gypsum extends from at least 1 300 to 900 m elevation in the deepest drill holes and has overprinted early potassic alteration or relatively unaltered red granodiorite meter wide zones of kaolinite cut the anhydrite gypsum at all levels there is an abrupt transition outward from the intermediate argillic alteration to chlorite epidote propylitic alteration at 50 to 200 m from the granodiorite porphyry contact although d veins and chalcopyrite extend outward to the propylitic zone the erdenet porphyry system was overprinted by advanced argillic alteration which outcrops 2 km northwest of the pit and forms a lithocap that extends over 10 2 5 km it is characterized by residual quartz andalusite na ca and k alunite diaspore pyrophyllite zunyite topaz dickite and kaolinite the upper part of the porphyry cu mo deposit removed by mining comprised a bornite chalcocite enriched zone up to 300 m thick with an average grade of 0 7 wt cu and up to 5 wt cu locally based on hypogene bornite chalcocite mineral textures and high sulfidation state mineralogy the enriched zone is inferred to be of hypogene origin but modified by supergene processes consequently it may be related to formation of the lithocap previous re os dates of 240 4 and 240 7 0 8 ma for molybdenite in quartz veins are comparable to new 40 ar 39 ar dates of 239 7 1 6 and 240 2 ma for muscovite that envelops d veins one 40 ar 39 ar date on k alunite from the lithocap of 223 5 1 9 ma suggests that it may be about 16 m y younger than erdenet but this result needs to be verified by further dating

uplift history of the sila massif southern italy deciphered from cosmogenic 10be erosion rates and river longitudinal profile analysis 1 the sila massif in the calabrian arc southern italy is a key site to study the response of a landscape to rock uplift here an uplift rate of 1 mm yr has imparted a deep imprint on the sila landscape recorded by a high standing low relief surface on top of the massif deeply incised fluvial valleys along its flanks and flights of marine terraces in the coastal belt in this framework we combined river longitudinal profile analysis with hillslope erosion rates calculated by 10be content in modern fluvial sediments to reconstruct the long term uplift history of the massif cosmogenic data show a large variation in erosion rates marking two main domains the samples collected in the high standing low relief surface atop sila provide low erosion rates from 0 09 0 01 to 0 13 0 01 mm yr conversely high values of erosion rate up to 0 92 0 08 mm yr characterize the incised fluvial valleys on the massif flanks the analyzed river profiles exhibit a wide range of shapes diverging from the commonly accepted equilibrium concave up form generally the studied river profiles show two or more frequently three concave up segments bounded by knickpoints and characterized by different values of concavity and steepness indices the wide variation in cosmogenic erosion rates and the non equilibrated river profiles indicate that the sila landscape is in a transient state of disequilibrium in response to a strong and unsteady uplift not yet counterbalanced by erosion

timing of post obduction granitoids from intrusion through cooling to exhumation in central anatolia turkey abstract the middle to late cretaceous central anatolian granitoids intrude the supra subduction zone type central anatolian ophiolite and medium to high grade metasediments of central anatolian crystalline complex and are overlain by late palaeocene to early middle eocene sediments their single zircon 207 pb 206 pb evaporation ages define three clusters 1 cenomanian turonian weighted mean age 94 9 3 4 ma 2 turonian santonian 85 5 5 5 ma and 3 campanian 74 9 3 8 ma their hornblende and biotite 40 ar 39 ar and k ar cooling ages cluster around 80 65 ma the close hornblende and biotite ages reflect rapid exhumation of a mid crustal section during the campanian maastrichtian early to middle palaeocene 57 62 ma apatite fission track age clusters date the tail end of this exhumation episode it is proposed that the central anatolian granitoid melts were generated in a post collisional extensional setting following the docking of an oceanic island arc onto the tauride anatolide platform campanian maastrichtian to early middle palaeocene rapid exhumation event is considered to result from continent continent collisions between eurasian plate and the tauride anatolide platform along the izmir ankara erzincan suture zone

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

triassic redbeds in the malaguide complex betic cordillera spain petrography geochemistry and geodynamic implications abstract sandstone petrography and mudstone mineralogy and geochemistry of triassic mudstones and sandstones from continental redbeds of the malaguide complex betic cordillera southern spain provide useful information on provenance palaeoclimate and geodynamics during the early stages of the pangea break up and on their diagenetic evolution the sandstones are quartzarenites to sub litharenites with minor lithic fragments and rare feldspars the mudstone samples show a paas like elemental distribution the samples likely record recycling processes from their metasedimentary basement rocks that significantly affected the weathering indices and monitors cumulative effects including a first cycle of weathering at the source rocks sandstone composition and chemical mineralogical features of mudstones record a provenance derived from continental block and recycled orogen that were weathered under warm and episodically wet climate source areas were located towards the east of the present day malaguide outcrops and were formed by fairly silicic rock types made up mainly of palaezoic metasedimentary rocks similar to those of the paleozoic underlying series with subordinate contributions from magmatic metamorphic sources and a rare supply from mafic metavolcanic rocks clay mineral distribution of mudstones is dominated by illite and illite smectite mixed layer that result from differences in provenance weathering and burial temperature history illite crystallinity values illitization of kaolinite occurrence of typical authigenic minerals and apatite fission track studies coupled with a subsidence analysis of the whole malaguide succession suggest burial depths of at least 4 6 km with temperatures of 140 160 c typical of the burial diagenetic stage and confirm the middle miocene exhumation of the betic internal domain tectonic stack topped by the malaguide complex

recrystallization of high pressure marble sivrihisar turkey abstract in the sivrihisar massif turkey the southern margin of a blueschist facies terrane was affected by heating and deformation associated with later regional barrovian metamorphism creating a recrystallization front that can be observed in calcite microstructures calcite marble records a progression from high pressure h p textures in a northern domain to completely recrystallized greenschist to amphibolite facies textures in a southern domain with intermediate stages of partial recrystallization of the h p textures h p marble is characterized by rod shaped calcite aragonite pseudomorphs arranged in series with the long axis of each grain oblique to compositional layering obliquity varies from 50 to nearly parallel but high angles are most common in a narrow 200 m thick transition zone that contains partially retrogressed blueschist and eclogite the h p texture is partially overprinted by chains of small equant recrystallized grains that preserve the crystallographic orientation of the pre existing rod shaped calcite as revealed by electron backscatter diffraction analysis rod shaped crystals occur locally in a 100 m thick zone south of the transition zone all calcite grains are equant but have a crystallographic preferred orientation further south in the barrovian sequence recrystallized marble contains equant calcite that is randomly oriented the similarity in fabric elements foliation lineation of the two domains further shows the effect of barrovian related processes on the h p domain including the rotation of the calcite rods during shearing along foliation planes white mica 40 ar 39 ar ages for phengite in h p marble are 88 ma and for muscovite in barrovian marble are 59 ma indicating 30 ma time interval between initial exhumation and cooling of the h p rocks and final cooling of the rocks that were deformed and heated during the later metamorphic event

reconstructing the geometry of central anatolia during the late cretaceous large scale cenozoic rotations and deformation between the pontides and taurides the central anatolian crystalline complex cacc exposes metamorphic ophiolitic and igneous rocks that were formed and deformed during closure of the neotethyan ocean the cacc is located in central turkey between the pontides in the north and the taurides in the south separated by major fault zones composite plutons intruded the meta sedimentary and ophiolitic units between 95 and 75 ma and form linear magmatic belts 100 km long along the western and northern margins of the cacc exhumation of the metamorphic and igneous complex was finalized by the paleocene time in this study we paleomagnetically study fifteen plutons spanning the entire non deformed upper cretaceous granitoid belt to test whether the initial configuration of the cacc was modified by vertical axis rotations after its exhumation our results show three internally coherent domains with significantly different vertical axis rotations 1 in the north east the akda block ayb records 151

the regolith in australia abstract australian regolith materials are described many of which are complex much australian regolith dates back to the tertiary mesozoic or earlier there is a progressive change in the nature of alluvium through the tertiary aridity revealed through sand dunes and evaporites is confined to the quaternary ferricretes and silcretes are formed on lower slopes often followed by inversion of relief tectonic isolation of australia as well as climatic change is responsible for the change in the nature of terrestrial sediments since the cretaceous

sedimentary evolution of the mesozoic continental redbeds using geochemical and mineralogical tools the case of upper triassic to lowermost jurassic monte di gioiosa mudrocks sicily southern italy the continental redbeds from the internal domains of the central western mediterranean chains have an important role in the palaeogeographic and palaeotectonic reconstructions of the alpine circum mediterranean orogen evolution since these redbeds mark the triassic jurassic rift valley stage of tethyan rifting the composition and the sedimentary evolution of the middle triassic to lowermost jurassic continental redbeds of the san marco d alunzio unit peloritani mountains southern italy based on mineralogical and chemical analyses suggests that the studied mudrock sediments share common features with continental redbeds that constitute the internal domains of the alpine mediterranean chains phyllosilicates are the main components in the mudrocks the 10 a minerals illite and micas the i s mixed layers and kaolinite are the most abundant phyllosilicates the amount of illitic layers in i s mixed layers coupled with the illite crystallinity values ic are typical of high degree of diagenesis corresponding to a lithostatic tectonic loading of about 4 5 km the mineralogical assemblage coupled with the a cn k plot suggest post depositional k enrichments palaeoweathering proxies pia and ciw record intense weathering at the source area further the studied sediments are affected by reworking and recycling processes and as consequence it is likely these proxies monitor cumulative effect of weathering the climate in the early jurassic favoured recycling and weathering occurred under hot episodically humid climate with a prolonged dry season the source area is the low grade paleozoic metasedimentary basement mafic supply is minor but not negligible as suggested by provenance proxies

compositional and geochemical signatures for the sedimentary evolution of the middle triassic lower jurassic continental redbeds from western central mediterranean alpine chains abstract compositional and chemical analyses suggest that middle triassic lower liassic continental redbeds in the internal domains of the betic maghrebian and apenninic chains can be considered a regional lithosome marking the triassic jurassic rift valley stage of tethyan rifting which led to the pangaea breakup and subsequent development of a mosaic of plates and microplates sandstones are quartzose to quartzolithic and represent a provenance of continental block and recycled orogen made up mainly of paleozoic metasedimentary rocks similar to those underlying the redbeds mudrocks display k enrichments intense paleoweathering under a hot episodically humid climate with a prolonged dry season and sediment recycling redbeds experienced temperatures in the range of 100 160 c and lithostatic tectonic loading of more than 4 km these redbeds represent an important stratigraphic signature to reconstruct a continental block mesomediterranean microplate that separated different realms of the west

tracking the timing of subduction and exhumation using 40ar 39ar phengite ages in blueschist and eclogite facies rocks sivrihisar turkey geochronologic studies of high pressure low temperature rocks can be used to determine the timing and rates of burial and exhumation in subduction zones by dating different stages of the pressure temperature history in this study we present new in situ uv laser ablation 40ar 39ar phengite ages from a suite of lawsonite blueschist and eclogite facies rocks representing different protoliths metabasalt metasediment different structural levels within and outside of a high strain zone and different textural positions eclogite pod core vs margin to understand the timing of these events in an exhumed neo tethyan subduction zone sivrihisar massif tavsanli zone turkey weighted mean in situ 40ar 39ar ages of phengite from the cores of lawsonite eclogite pods 90 93 ma are distinctly older than phengite from retrogressed epidote eclogite 82 2 ma these ages are interpreted as the age of peak and retrograde metamorphism respectively eclogite records the narrowest range of ages 10 14 m y of any rock type analyzed transitional eclogite and blueschist facies assemblages and glaucophane rimmed lawsonite garnet phengite veins from eclogite pod margins record a much wider age range of 40ar 39ar ages 20 m y with weighted mean ages of 91 ma blueschists and quartzites record more variable 40ar 39ar ages that may in part be related to structural position samples within a high strain zone at the tectonic contact of the hp rocks with a meta ultramafic unit have in situ uv laser ablation 40ar 39ar ages of 84 0 1 3 103 7 3 1 ma whereas samples outside this zone range to older ages 84 6 2 4 116 7 2 7 ma and record a greater age range 22 38 m y the phengite ages can be correlated with the preservation of hp mineral assemblages and fabrics as well as the effects of deformation collectively these results show that high spatial resolution uv laser ablation 40ar 39ar phengite data when considered in a petrologic and structural context may document prograde burial and retrograde exhumation stages of subduction metamorphism

tectonic evolution and paleogeography of the kirsehir block and the central anatolian ophiolites turkey in central and western anatolia two continent derived massifs simultaneously underthrusted an oceanic lithosphere in the cretaceous and ended up with very contrasting metamorphic grades high pressure low temperature in the tavsanli zone and the low pressure high temperature in the kirsehir block to assess why we reconstruct the cretaceous paleogeography and plate configuration of central anatolia using structural metamorphic and geochronological constraints and africa europe plate reconstructions we review and provide new 40ar 39ar and u pb ages from central anatolian metamorphic and magmatic rocks and ophiolites and show new paleomagnetic data on the paleo ridge orientation in a central anatolian ophiolite intraoceanic subduction that formed within the neotethys around 100 90 ma along connected n s and e w striking segments was followed by overriding oceanic plate extension already during suprasubduction zone ocean spreading continental subduction started we show that the complex geology of central and southern turkey can at first order be explained by a foreland propagating thrusting of upper crustal nappes derived from a downgoing dominantly continental lithosphere the kirsehir block and tavsanli zone accreted around 85 ma the afyon zone around 65 ma and taurides accretion continued until after the middle eocene we find no argument for late cretaceous subduction initiation within a conceptual inner tauride ocean between the kirsehir block and the afyon zone as widely inferred we propose that the major contrast in metamorphic grade between the kirsehir block and the tavsanli zone primarily results from a major contrast in subduction obliquity and the associated burial rates higher temperature being reached upon higher subduction obliquity

modelling the structural controls of primary kaolinite formation abstract an abundance of kaolinite was formed within the st austell outcrop of the cornubian batholith in cornwall southwest england by the hydrous dissolution of feldspar crystals the permeability of cornish granites is low and alteration acts pervasively from discontinuity features with montmorillonite recognised as an intermediate assemblage in partially kaolinised material structural features allowed fluids to channel through the impermeable granite and pervade deep into the rock areas of high structural control are hypothesised to link well with areas of advanced alteration as kaolinisation results in a loss of competence we present a method of utilising discontinuity orientations from nearby unaltered granites alongside the local tectonic history to calculate strain rates and delineate a discrete fracture network simulation of the discrete fracture network is demonstrated through a case study at higher moor where kaolinite is actively extracted from a pit reconciliation of fracture connectivity and permeability against measured subsurface data show that higher values of modelled properties match with advanced kaolinisation observed in the field this suggests that the technique may be applicable across various industries and disciplines