spherulites in calcrete laminar crusts biogenic caco 3 precipitation as a major contributor to crust formation abstract spherulites calcitic fibro radial spherulitic polycrystals are a major component of calcite layers in quaternary calcrete laminar crusts to explain the formation of spherulites petrographic and chemical studies were performed on pleistocene calcrete laminar crusts holocene biological crusts and laboratory in vitro cultures of cyanobacterial strains spherulites were found to be formed of acicular and radiating crystals either smooth and regular edged or twisted and irregular edged spherulites were composed of low mg calcite the concentration of mg in the spherulites increasing from nucleus to periphery the shape and chemistry of the in vitro spherulites and laminar crust spherulites were identical the structure elementary crystal shape and size of spherul tes can be used to differentiate them from microcodium with which they are commonly confused in the literature spherulite genesis can be linked to cyanobacterial activity involving photosynthetic uptake of hco 3 leading to caco3 precipitation the bicarbonate causing release of equivalent amounts of oh in the mucilaginous sheath the main steps in cyanobacteria biomineralization producing spherulites are 1 uptake of co2 and or hco 3 from the medium as the inorganic carbon source for photosynthesis 2 release of oh in the sheath 3 carbonate ion formation resulting from the reaction of oh and hco 3 followed by 4 caco3 precipitation this process involves two steps in desert environments during dry spells the cyanobacterial mat calcifies leading to spherulite production and the fo mation of thin clear microsparitic layers during wet periods a thin sedimentary deposit forms mixing micrite detrital particles and inherited or new tiny spherulites with the mucilaginous mat of cyanobacteria which traps all of this material an organo micritic layer forms during the following dry spell the process is repeated and the laminar crust is formed in conclusion the presence of spherulites in the laminar crust is indicative of subaerial exposure the crust being a terrestrial stromatolite

earthquake generated tsunamis in the mediterranean sea scenarios of potential threats to southern italy italian civil defense project development of new technologies for the protection of the italian territory from natural hazards funded by the italian ministry of university and research

pedogenic carbonates forms and formation processes abstract soils comprise the largest terrestrial carbon c pool containing both organic and inorganic c soil inorganic carbon sic was frequently disregarded because 1 it is partly heritage from soil parent material 2 it undergoes slow formation processes and 3 has very slow exchange with atmospheric co2 the global importance of sic however is reflected by the fact that sic links the long term geological c cycle with the fast biotic c cycle and this linkage is ongoing in soils furthermore the importance of sic is at least as high as that of soil organic carbon soc especially in semiarid and arid climates where sic comprises the largest c pool considering the origin formation processes and morphology carbonates in soils are categorized into three groups geogenic carbonates gc biogenic carbonates bc and pedogenic carbonates pc in this review we summarize the available data and theories on forms and formation processes of pc and relate them to environmental factors after describing the general formation principles of pc we present the specific forms and formation processes for pc features and the possibilities to use them to reconstruct soil forming factors and processes the following pc are described in detail earthworm biospheroliths rhizoliths and calcified roots hypocoatings nodules clast coatings calcretes and laminar caps the second part of the review focuses on the isotopic composition of pc 13c 14c and 18o as well as clumped 13c and 18o isotopes known as 47 the isotopic signature of pc enables reconstructing the formation environment the dominating vegetation 13c temperature 18o and 47 and the age of pc formation 14c the uncertainties in reconstructional and dating studies due to pc recrystallization after formation are discussed and simple approaches to consider recrystallization are summarized finally we suggest the most important future research directions on pc including the anthropogenic effects of fertilization and soil management in conclusion pc are an important part of sic that reflect the time periods and formation processes in soils a mechanistic understanding of pc formation is a prerequisite to predict terrestrial c stocks and changes in the global c cycle and to link the long term geological with short term biological c cycles

state of stress in the southern tyrrhenian subduction zone from fault plane solutions summary in this paper we present revised locations and original focal mechanisms computed for intermediate and deep earthquakes that occurred within the southern tyrrhenian subduction zone between 1988 and 1994 in order to improve our knowledge of the state of stress for this compressional margin in particular we define the stress distribution within a large portion of the descending slab between 40 and about 450 km depth the seismicity distribution reveals a continuous 40 50 km thick slab that abruptly increases its dip from subhorizontal in the ionian sea to a constant 70 dip in the tyrrhenian we computed focal mechanisms for events with magnitudes ranging from 2 7 and 5 7 obtaining the distribution of p and t axes for many events for which centroid moment tensor cmt solutions are not available thus enabling the sampling of a larger depth range compared to previous studies we define three portions of the slab characterized by different distributions of p and t axes a general down dip compression is found between 165 and 370 km depth whereas in the upper part of the slab 40 165 km depth the fault plane solutions are strongly heterogeneous below 370 km the p axes of the few deep events located further to the north have a shallower dip and are not aligned with the 70 dipping slab possibly suggesting that they belong to a separated piece of subducted lithosphere there is a good correspondence between the depth range in which the p axes plunge closer to the slab dip 70 and the interval characterized by the highest seismic energy release 190 370 km

spatial variation in stresses in peninsular italy and sicily from background seismicity abstract we have retrieved the stress tensor orientation in the italian region applying the fmsi technique gephart j 1990b fmsi a fortran program for inverting fault slickenside and earthquake focal mechanism data to obtain the regional stress tensor comput geosci 16 953 989 to fault plane solutions of 298 small earthquakes 2 5 m d istituto nazionale di geofisica in the period 1988 1995 first we verified that the stress inversion procedure generally applied to a large number of focal mechanisms of earthquakes recorded in a local seismic network could be successfully used in italy using background seismicity recorded over large 100 200 km regions then comparing the stress inversion results with other stress indicators we find that they are geologically sound for many regions in italy even if the misfit values are relatively large we also find that the largest misfit values are determined by a few earthquakes only 10 20 of the total number excluding these earthquakes from inversion the average misfit becomes much lower by 30 40 the results obtained in this study confirm the large variations of the stress field over a relatively short distance in italy but also confirm the existence of regions extending for a few hundred kilometres within which the stress is homogeneous among these most of the apennines are dominated by extension perpendicular to the trend of the mountain belt only in the northern apennines is there any clear distinction between an area of extension in the inner portion of the belt and an area under horizontal compression along the adriatic margin of the belt more rapid variations occur around calabria and sicily as expected because of the complexities linked with the tyrrhenian subduction and with active volcanism in the ionian calabrian coastal region there are hints of active nw se compression although constrained by a few data whereas in the messina strait we observe e w extension and a vertical 1 in northern and western sicily our results indicate n s to nw se compression roughly consistent with the general convergence between the european and the african plates

a revision of the 1693 eastern sicily earthquake and tsunami the 1693 earthquake was a disastrous event affecting eastern sicily southern italy where it caused over 60 000 victims and total destruction of several villages and towns in the districts of siracusa ragusa and catania the earthquake was followed by a tsunami that struck the ionian coasts of sicily and the messina strait and was probably observed even in the aeolian islands historical documents on sea waves and flooding though not abundant allow us to form a picture of the tsunami first attack and inundation the first water movement all along the sicilian coastline was a strong sea withdrawal followed by a violent sea return and coastal flooding the main purpose of this research is to put constraints on the focal mechanism of this earthquake on the basis of the available documents on the tsunami 1 by simulating tsunami from different possible sources via numerical modeling based on finite element technique and shallow water approximation and 2 by choosing the source best fitting the tsunami data as the most plausible cause for this tsunami the relevance of this study should also be evaluated in light of the circumstance that no certain indication on the earthquake fault can be deduced from the available macroseismic data alone solving the source problem for this event one of the largest occurring in southeastern sicily in historical times is a significant contribution to understanding the seismotectonic regime of the region and to assessing the related earthquake and tsunami hazard risk with implications on mitigation policies

depth to pedogenic carbonate horizon as a paleoprecipitation indicator comment and reply royer 1999 1 has recently used a large data set from the u s natural resources conservation service nrcs to reexamine the relationship between mean annual precipitation and depth to the calcic horizon in soils the extremely poor correlation between these variables in his nrcs data r2 0

formation and preservation of pedogenic carbonates in south india links with paleo monsoon and pedological conditions clues from sr isotopes u th series and rees the influence of the pedogenic and climatic contexts on the formation and preservation of pedogenic carbonates in a climosequence in the western ghats karnataka plateau south west india has been studied along the climosequence the current mean annual rainfall mar varies within a 80 km transect from 6000 mm at the edge of the plateau to 500 mm inland pedogenic carbonates occur in the mar range of 500 1200 mm in the semi arid zone mar 500 900 mm carbonates occur i as rhick hardpan calcretes on pediment slopes and ii as nodular horizons in polygenic black soils i e vertisols in the sub humid zone mar 900 1500 mm pedogenic carbonates are disseminated in the black soil matrices either as loose irregular and friable nodules of millimetric size or as indurated botryoidal nodules of centimetric to pluricentimetric size they also occur at the top layers of the saprolite either as disseminated pluricentimetric indurated nodules or carbonate cemented lumps of centimetric to decimetric size chemical and isotopic sr 87 sr 86 compositions of the carbonate fraction were determined after leaching with 0 25 n hcl the corresponding residual fractions containing both primary minerals and authigenic clays were digested separately and analyzed the trend defined by the sr 87 sr 86 signatures of both labile carbonate fractions and corresponding residual fractions indicates that a part of the labile carbonate fraction is genetically linked to the local soil composition considering the residual fraction of each sample as the most likely lithogenic source of ca in carbonates it is estimated that from 24 to 82 55 on average of ca is derived from local bedrock weathering leading to a consumption of an equivalent proportion of atmospheric co2 these values indicate that climatic conditions were humid enough to allow silicate weathering mar at the time of carbonate formation likely ranged from 400 to 700 mm which is 2 to 3 fold less than the current mar at these locations the sr u and mg contents and the u 234 u 238 activity ratio in the labile carbonate fraction help to understand the conditions of carbonate formation the relatively high concentrations of sr u and mg in black soil carbonates may indicate fast growth and accumulation compared to carbonates in saprolite possibly due to a better confinement of the pore waters which is supported by their high u 234 u 238 signatures and or to higher content of dissolved carbonates in the pore waters the occurrence of ce mn and fe oxides in the cracks of carbonate reflects the existence of relatively humid periods after carbonate formation the carbonate ages determined by the u th method range from 1 33 0 84 kyr to 7 5 2 7 kyr and to a cluster of five ages around 20 kyr i e the last glacial maximum period the young occurrences are only located in the black soils which therefore constitute sensitive environments for trapping and retaining atmospheric co2 even on short time scales the maximum age of carbonates depends on their location in the climatic gradient from about 20 kyr for centimetric nodules at mule hole mar 1100 mm yr to 200 kyr for the calcrete at gundlupet mar 700 mm yr durand et al 2007 the intensity of rainfall during wet periods would indeed control the lifetime of pedogenic carbonates and thus the duration of inorganic carbon storage in soils c 2010 elsevier ltd all rights reserved

microbial origin for pedogenic micrite associated with a carbonate paleosol champagne france abstract micro rods have been observed in indurated carbonate horizons 30 cm thick that overlie a periglacial chalk formation in contact with the present day soil champagne france they are numerous in the upper part of the hardened layers variations in micro rod morphologies are related to progressive biomineralization of organic matter transforming purely organic rods into calcite mineralized rods undergo diagenesis and their arrangement evolves from a random mesh fabric to recrystallized micritic platelets to microsparite two types of organic micro rods have been observed bacilliform and thread like bacteria mineralogically micro rods are low magnesian calcite crystallographically their length is parallel to the 104 axis and they grow along the 010 plane micro rods can be associated with needle fiber calcite they increase the caco3 content of the primary matrix and infill its microporosity their diagenetic evolution into microsparite contributes to soil layer induration

kalahari valley calcretes their nature origins and environmental significance abstract calcretes that form in non pedogenic settings have been widely reported in the geomorphological and geological literature yet they are still poorly understood in comparison with pedogenic varieties this may be because there are assorted types of non pedogenic calcretes often loosely referred to as groundwater calcretes but encompassing groundwater phreatic open valley or confined channel calcrete types forming within vadose and phreatic environments in different geomorphological settings relatively few studies have described the detailed petrological characteristics of such calcretes leading wright and tucker calcretes international association of sedimentologists reprint series 1991 vol 2 blackwell scientific publications oxford p 10 to suggest that much more work is needed to define the groundwater calcrete facies and to devise criteria for its recognition so that the various non pedogenic calcretes can be identified within the quaternary as well as further back in the geological record most descriptions of groundwater calcretes are highly generalistic and do not take into account the variability that may occur as a result of calcretes forming in different positions within a landscape and affected by separate controls thus the range of groundwater calcretes that exists now needs to be studied individually to identify patterns within the distinct types as a step towards expanding our knowledge of the variety of non pedogenic calcretes this paper describes the petrology micromorphology and mode of development of one of these types of calcrete namely that which forms within valley locations but not in definite fluvial channels late quaternary to holocene valley calcretes are described from various dry valleys mekgacha across the kalahari region of central botswana with the majority of samples collected from trunk and tributary valleys of the okwa samples have been analysed in thin section and under scanning electron microscope in order to determine the carbonate matrix type and calcrete micromorphology in general most samples consist of grains of quartzose kalahari sand cemented by fine crystalline often glaebular grain coating and pore filling micrite cement types are fairly consistent and not as micromorphologically variable as has been noted for other kalahari calcretes biological inputs are prevalent in many samples and include networks of calcified rootlets these characteristics reflect the fact that the calcretes formed in a relatively near surface environment with relatively high rates of evaporation

active faulting and seismicity along the siculo calabrian rift zone southern italy abstract southern italy is dominated by extensional tectonics that in the calabrian arc and eastern sicily produced the development of the siculo calabrian rift zone scrz this zone is represented by a 370 km long fault belt consisting of 10 to 50 km long distinct fault segments which extend both offshore and on land being also responsible of the crustal seismicity of this region the geological and morphological observations indicate that the active normal faults of the scrz are characterized by throw rates ranging from 0 7 to 3 1 mm a they accommodate an almost uniform horizontal extension rate of about 3 0 mm a along a wnw ese regional extension direction based on our field observations and following empirical relationships between magnitude and surface rupture length connections between large crustal earthquakes and distinct fault segments of the scrz have been also tentatively tested our data indicate moreover that the magnitudes m of the historical and instrumental earthquakes are consistent with the estimated values and that the geometry and kinematics of the fault segments and the related different crustal features of the scrz control the different seismic behaviours of adjacent portions of the active rift zone

introducing a terrestrial carbon pool in warm desert bedrock mountains southwestern usa growth of the phoenix metropolitan area led to road cut or house platform exposures of the internal bedrock material of surrounding semiarid mountain ranges similar exposures in the surrounding sonoran and mojave deserts reveal the presence of sedimentary calcium carbonate infilling the preexisting fracture matrix of the bedrock field surveys at 31 sites with bedrock fractures filled with carbonate referred to as bffc in the following text reveal an average of 0 079 0 036 mtc m2 stored in the upper 2 m of analyzed bedrock exposures backscattered electron microscopy images indicate the presence of carbonate at the micron scale not included in this estimate of carbon storage pilot radiocarbon and sr isotope analyses suggest that one of the surveyed bffc veins was flushed into the bedrock from a nonbedrock source during the wetter last glacial period in the late pleistocene

strontium and carbon isotope tracers and the origins of soil carbonate in south australia and victoria abstract calcium carbonate occurs in soils in association with a variety of rock types in coastal and inland south australia and victoria the 87 sr 86 sr ratios of the coastal soil carbonates fall between 0 7094 and 0 7098 showing that the ocean is the principal source of calcium to nearly all soils near the coast and that contributions from bedrock are generally small an exception is the soil formed on the young volcano at mt gambier in which the average ratio for carbonate is about 0 7070 compared to 0 7041 for the volcanic ash the basaltic ash of the volcano is readily weathered and rich in calcium roughly 40 of strontium and 10 to 20 of the calcium in the soil carbonate derives from the ash and the balance from marine sources the 87 sr 86 sr ratios from soil carbonate gradually increase inland reaching values of 0 7152 these higher ratios reflect at least in part the increasing 87 sr 86 sr ratio of inland dust in contrast the ocean does not contribute significantly to the carbon pool of the soils we studied the 13 c pdb values of soil carbonates on kangaroo island and the higher rainfall areas of eastern victoria fall between 11 0 and 8 7 indicating that the carbonate formed in equilibrium with the c3 dominated vegetation typical of the region in the warmer inland areas to the north such as the eyre peninsula the 13 c value of soil carbonate averages 5 3 reflecting the higher proportion of c4 plants in the local biomass mixing with marine sources of carbonate cannot account for the observed carbon isotopic patterns the flux of carbon into soils from the ocean therefore must be small compared to that derived from plant respiration and decay

using a structural approach to identify relationships between soil and erosion in a semi humid forested area south india biogeochemical and hydrological cycles are currently studied on a small experimental forested watershed 4 5 km 2 in the semi humid south india this paper presents one of the first data referring to the distribution and dynamics of a widespread red soil ferralsols and chromic luvisols and black soil vertisols and vertic intergrades cover and its possible relationship with the recent development of the erosion process the soil map was established from the observation of isolated soil profiles and toposequences and surveys of soil electromagnetic conductivity em31 geonics ltd lithology and vegetation the distribution of the different parts of the soil cover in relation to each other was used to establish the dynamics and chronological order of formation results indicate that both topography and lithology gneiss and amphibolite have influenced the distribution of the soils at the downslope the following parts of the soil covers were distinguished i red soil system ii black soil system iii bleached horizon at the top of the black soil and iv bleached sandy saprolite at the base of the black soil the red soil is currently transforming into black soil and the transformation front is moving upslope in the bottom part of the slope the chronology appears to be the following black soil bleached horizon at the top of the black soil streambed bleached horizon below the black soil it appears that the development of the drainage network is a recent process which was guided by the presence of thin black soil with a vertic horizon less than 2 in deep three distinctive types of erosional landforms have been identified 1 rotational slips type 1 2 a seepage erosion type 2 at the top of the black soil profile 3 a combination of earthflow and sliding in the non cohesive saprolite of the gneiss occurs at midslope type 3 types 1 and 2 erosion are mainly occurring downslope and are always located at the intersection between the streambed and the red soil black soil contact neutron probe monitoring along an area vulnerable to erosion types 1 and 2 indicates that rotational slips are caused by a temporary watertable at the base of the black soil and within the sandy bleached saprolite which behaves as a plane of weakness the watertable is induced by the ephemeral watercourse erosion type 2 is caused by seepage of a perched watertable which occurs after swelling and closing of the cracks of the vertic clay horizon and within a light textured and bleached horizon at the top of black soil type 3 erosion is not related to the red soil black soil system but is caused by the seasonal seepage of saturated throughflow in the sandy saprolite of the gneiss occurring at midslope c 2006 elsevier b v all rights reserved

the characterization of steady state in earth surface systems findings from the gradient modelling of an indian climosequence abstract gradient modelling of a steep ecocline in south india has highlighted a suite of landscape units which appear to be entirely ordained by a simple water balance index this univariate climofunction is reflected in vegetation landform weathering and soil patterns although the vegetation successions are the most spectacular consistent pedogeomorphological trends were identified at several embedded scales of reality at the microscopic scale the existence of illite rich saprolite situated between the kaolinite dominated and smectite dominated core areas of the climosequence so far a missing mineralogical link only predicted by geochemical theory was effectively verified by field evidence at the megascopic scale the variation in topographic texture from polyconvex to polyconcave land systems via a convexo concave transition zone also suggests a strong relationship between hydroclimatic budgets and landforms such an exceptional environmental cabinet is well suited to reexamining other benchmark climosequences of the tropics and to readdressing the debated theories of climatic geomorphology by a discussion on the applicability of climax and steady state to tropical landforms

pattern and rate of post 20 ka vertical tectonic motion around the capo vaticano promontory w calabria italy based on offshore geomorphological indicators abstract the magnitude and rate of late pleistocene holocene vertical tectonic movements offshore of the capo vaticano promontory western calabria southern italy have been measured on the basis of the present day depth variations of the edges of submerged depositional terraces and associated abrasion platforms that formed below the storm wave base during the sea level stillstand of the last glacial maximum lgm these depositional features represented by submerged prograding wedges and an associated terrace shaped upper boundary have been identified in high resolution seismic reflection profiles acquired along the continental shelf and the upper slope of the promontory and are referred to in this study as lowstand infralittoral prograding wedges lipws our new data and methods provide evidence that lipws can be used as geomorphological indicators of vertical movements in offshore settings with well controlled uncertainty removal of the non tectonic component of vertical changes using an ice volume equivalent eustatic sea level compilation indicates 11 3 2 m of uplift and 25 3 2 m of subsidence from southwest to northeast along the promontory over a distance of 22 km during the post lgm the resulting uplift and subsidence rates including both regional and local components for the last 20 350 1 35 years are 0 54 0 2 mm y and 1 23 0 25 mm y respectively these results are consistent with longer term estimates based on uplifted 215 82 ka old coastal terraces and late holocene shorelines this integration of offshore and coastal markers indicates a pattern of vertical movements characterized by a marked asymmetry associated with a northeast down tilt of the capo vaticano promontory the calculated tilt rate increases by one order of magnitude during the post lgm in respect to the time interval from 215 to 82 bp displacement associated with the nw se striking normal fault that bound the capo vaticano promontory to the gioia tauro basin ended in the pleistocene and thus does not contribute to the tilt of the promontory at least during the last 215 ka

the use of scenarios to evaluate the tsunami impact in southern italy this paper outlines the main contributions to the definition and evaluation of tsunami hazard and risk resulting from studies undertaken in italy in recent years and emphasises that adopting characteristic cases or scenarios is a very useful and advantageous technique three main cases are given as valuable examples that is the 1627 gargano tsunami the 1693 eastern sicily tsunami and the 1908 messina straits tsunami since 1 they characterise three distinct tsunamigenic regions 2 they are instances of destructive events and 3 they have been extensively studied in the last decade the paper elucidates the state of the art of the research on these events clarifies the chief points of agreement and disagreement among scientists and illustrates the main issues that are to be addressed by future research to provide reliable assessment of tsunami risk and to implement efficient countermeasures to defend the life of people coastal structures and the coastal environment against the attacks of tsunamis

fluvial response to late quaternary climate changes western india we review here the fluvial response to late quaternary climatic changes in the semi arid regions of western india i e the thar desert and its margins and maharashtra the rivers in the thar desert show a spectrum of environments from gravel bedload braided to ephemeral sand bed streams to sheet flows and sheet floods while those in the thar margin and maharashtra show dominantly two modes i e braided and meandering rivers the streams became defunct and aeolian sands were deposited during periods of relatively greater aridity in the thar desert and its margins incisions occurred during the wet phases in ois 1 it is inferred that changes in the monsoon precipitation led to relative changes in the discharge and sediment supply which were routed through those in the vegetation cover and played a key role in determining the fluvial style an inter comparison of the late quaternary alluvial deposits in the semi arid regions of western india suggests a continuum of fluvial environments interrelated through a precipitation gradient further a global comparison indicates that the response of semi arid western indian rivers was synchronous with the rivers in other climatic settings

the 1905 calabria southern italy earthquake hypocenter location causative process and stress changes induced in the area of the 1908 messina straits earthquake

numerical modelling of the september 8 1905 calabrian southern italy tsunami summary this paper presents a study of the tsunami following the disastrous earthquake that occurred on the 8th of september 1905 in calabria southern italy the shock caused devastation in many towns and villages leading to more than 500 victims according to coeval sources the tsunami was not catastrophic but was large enough to inundate low lying lands in several coastal segments and to affect boats no specific study was ever devoted to this tsunami in the literature our analysis is carried out by means of numerical modelling and aims at filling this gap since the source fault of the earthquake has not yet been identified we study three tsunamis produced by likely potential sources according to macroseismic data and the seismotectonic knowledge of the region namely the capo vaticano cv fault the vibo valentia vv fault and the lamezia la fault we compute tsunami waves under the hypotheses that the sea floor deformation is caused by a shear double couple dislocation taking place over a rectangular fault and that sea waves propagate according to the shallow water approximation the three tsunamis cause either a pure initial depression vv and la or a predominant initial depression cv of the sea surface in the gulf of st eufemia one very relevant finding is that tsunami energy is trapped within a narrow channel along the calabrian coast to the north of the source with the consequence that wave amplitudes computed here are much larger than the values expected in the case of an ordinary energy decay law with distance energy trapping along southern coastal segments is less efficient only a small fraction of tsunami energy penetrates the straits of messina to the south propagation to the west is affected by the aeolian islands that produce a quasi shadow zone on the side opposite to the tsunami impact the la tsunami is found to be too weak to be compatible with observations a sensitivity analysis concerning some parameters of the faults namely length width and slip magnitude has been performed in order to explore their influence on the tsunami features the main result of this paper is that we cannot discriminate between the cv and vv sources both are in agreement with some historical observations whilst they do not match others we believe that a better tuning of the source mechanism over these faults can improve the agreement between model computations and historical observations

webgis for italian tsunami a useful tool for coastal planners abstract ritmare is the italian contribution to a sea research program promoted by the european commission aiming to create an integrated maritime policy in this context a geodatabase about tsunami events recorded along the italian coasts as reported in recent scientific papers has been realized each scientific paper occurring in the geodatabase is linked to its area of interest by means of a geographical information system gis the geodatabase is available on the ritmare website www ritmare it through a map server

depth to pedogenic carbonate horizon as a paleoprecipitation indicator an analysis of 1168 modern soil profiles from the u s natural resources conservation service yields no correlation between mean annual precipitation and depth to the top of the carbonate horizon r 2 0 03 p 0 001 parent material and soil texture both play negligible roles in this regression when combined with similar published studies n 1481 r 2 improves slightly r 2 0 31 p 0 001 caution is therefore advised in using this or any previously published regression for inferring paleoprecipitation from paleosols however in the combined data set carbonate horizon bearing soils correlate with a mean annual precipitation of 760 mm p 0 05 thus the presence vs absence of pedogenic calcium carbonate is a good indicator of paleoprecipitation above or below this value

geochemistry of calcretes calcic palaeosols and hardpan coimbatore southern india formation and paleoenvironment abstract there is no major chemical variation in the late quaternary calcic nodules formed within vertisols in the foot hill regions and hardpan calcretes greater than 200 ka formed over the precambrian substrate that occur as duricrust horizons in the plains around coimbatore region tamil nadu india the bulk chemistry of calcic nodules and the hardpan calcretes show very little variability in cao sio2 al2o3 and fe2o3 content the trend of trace metal content in calcic nodules and in the hardpan calcrete is mn zn ni cr pb co cu and zn mn ni co pb cu cr respectively paas normalised ree data of the calcretes calcic nodules and the hardpan demonstrate a positive euanomaly this could be attributed to feldspar apatite mineral alteration and soil digenetic processes differential weathering leaving behind plagioclase phenocrysts and apatite grains which are enriched in eu the stable isotope values of the calcic nodules do not exhibit a wide range 18o 3 39 to 5 84 and 13c 3 01 to 6 64 compared to the hardpan calcretes 18o 2 91 to 12 98 and 13c 0 05 to 7 4 the palaeoenvironment during the formation of the calcretes nodules was dominated by the c4 plants with sparse vegetation cover and that the parent material bedrock supported a thin veneer of soil column with sparse vegetation cover as present day calcic nodule accumulations in the soils has resulted from differential weathering and chemical histories within the soil profiles while the hardpan calcretes formed by complex pedogenic and chemical groundwater processes in arid semi arid conditions over along geological period during the late mis3 to the lgm period the south west monsoon was weak with mean annual rainfall mar between 300 and 500 mm yr the sea level was low and the rainfall at the time of carbonate formation would have remained damp enough to allow silicate weathering of the soil sediments

biogenic β fabric features in the hard laminated crusts of the mersin and adana regions southern turkey and the role of soil organisms in the formation of the calcrete profiles abstract this paper describes fabric features and their distribution in the calcretes and emphasizes the role of soil organisms in the formation of the calcrete profiles quaternary calcretes are common in the mersin and adana provinces occurring as powdery nodular tubular fracture infill and various forms of crusts the stable isotope values indicate calcrete development under semi arid climatic conditions and a pedogenic origin biogenic or fabric constituents are abundant in the hard laminated crust these are the rhizoliths alveolar septal structures needle fiber calcites calcified filaments spherical calcite bodies microcodium and vadose calcrete pisoliths rhizoliths have mainly formed by the petrification of roots and often contain cellular cortex structures the alveolar septal structure comprises root voids separated by a micritic wall or a bundle of tangentially oriented calcite needles needle fiber calcite is common in the hard laminated crust as monocrystalline rods and polycrystalline needles monocrystalline rods are smooth and small

soils and climatic geomorphology on the karnataka plateau peninsular india abstract as a result of extensive field reconnaissance in southern india a geographical traverse across the planation surface of the karnataka uplands which lie in the rainshadow of the western ghats was selected to assess the consequences of a steep rainfall gradient on soil and landform patterns the study of the traverse described in detail reveals a characteristic progression of soil type and wash divide form from the high rainfall to the semi arid end of the continuum and invites a critical reappraisal of classical notions in climatic geomorphology and the soil sciences the assumption that alternations of wet and dry climates are necessary to achieve planation is given special consideration and the often held belief that kaolinite minerals are diagnostic of humid palaeoclimates when found in a semi arid climate is challenged the findings for the indian traverse are set against the better known data for west africa where the rainfall range between the gulf of guinea and the sahel is comparable with that observed in the south western deccan differences outweighing similarities attention is drawn to the possibility that tectonic regime which also controls the degree of landscape stripping is a major key to understanding the climatic geography of soils the tread of planation surfaces and the shape of hillslopes from one region of the tropics to another

u series isochron dating a generalized method employing total sample dissolution the age of a sedimentary deposit can be determined by measuring 238u 234u 232th and 230th in two or more samples of the deposit with the requirement that these samples have different u th ratios but an identical 230th232th ratio when deposited this paper presents the theoretical and experimental aspects of the dating method the latter involves techniques for securing samples of varied u th ratios from the same deposit plotting isochrons of the radiochemical data obtained on totally dissolved samples for age analysis and estimating the errors involved although applications to impure carbonates and lacustrine evaporite sediments are given as examples in this paper the method potentially can be generalized for dating a variety of authigenic deposits such as rock varnish peat opal sulfate minerals and marine phosphorites

a classification of rhizogenic root formed calcretes with examples from the upper jurassic lower cretaceous of spain and upper cretaceous of southern france reply abstract studies of fluvial sequences from the upper jurassic and lower cretaceous of the cameros basin spain and the upper cretaceous of the aquitaine basin france have revealed large numbers of calcrete profiles which have formed wholly or largely through the action of plant root calcification those from spain have formed by the calcification of root mats whereas those from france resulted from the accumulation of calcified root cells microcodium these root related rhizogenic calcretes developed in stages allowing developmental time series chronosequences to be identified contrasting with existing models for calcrete profile growth they provide unique examples where vegetation has been the dominant control on profile development and probably indicate specific vegetation types and palaeoecological settings the role of root activity in forming some quaternary calcretes is also discussed

approaching the seismogenic source of the calabria 8 september 1905 earthquake new geophysical geological and biochemical data from the s eufemia gulf s italy abstract recognizing the seismogenic source of major historical earthquakes particularly when these have occurred offshore is a long standing issue across the mediterranean sea and elsewhere the destructive earthquake m 7 that struck western calabria southern italy on the night of 8 september 1905 is one such case having various authors proposed a seismogenic source with apparently diverse hypotheses and without achieving a unique solution to gain novel insight into the crustal volume where the 1905 earthquake took place and to seek a more robust solution for the seismogenic source associated with this destructive event we carried out a well targeted multidisciplinary survey within the gulf of s eufemia se tyrrhenian sea collecting geophysical data oceanographic measurements and biological chemical and sedimentary samples we identified three main tectonic features affecting the sedimentary basin in the gulf of s eufemia 1 a ne sw striking ca 13 km long normal fault here named s eufemia fault 2 a wnw striking polyphased fault system and 3 a likely e w trending lineament among these the normal fault shows evidence of activity witnessed by the deformed recent sediments and by its seabed rupture along which locally fluid leakage occurs features in agreement with the anomalous distribution of prokaryotic abundance and biopolymeric c content resulted from the shallow sediment analyses the numerous seismogenic sources proposed in the literature during the past 15 yr make up a composite framework of this sector of western calabria that we tested against a the geological evidence from the newly acquired dataset and b the regional seismotectonic models such assessment allows us to propose the ne sw striking normal fault as the most probable candidate for the seismogenic source of the 1905 earthquake reappraising a major historical earthquake as the 1905 one enhances the seismotectonic picture of western calabria further understanding of the region and better constraining the location of the seismogenic source may be attained through integrated interpretation of our data together with a on land field evidence and b seismological modeling

needle fiber calcite a critical review and a proposed classification abstract from a review of the recent literature and our own observations the different morphologies of needle fiber calcite are classified they can be characterized as monocrystalline rods with or without serrated edges or as polycrystalline chains the simplest monocrystalline habit of needle fiber calcite is the individual micro rod m larger monocrystalline rods ma exist in multiples of two more complex forms are found as paired monocrystalline rods with serrated plates along their length mb this group includes three habits which can be distinguished by the number of plates and their orientation relative to the rod finally there is a monocrystalline form mab intermediate between the categories ma and mb which shows the transition from the simple coupled rods to rods with errated plates although polycrystalline needles p have rarely been reported in the literature three types of morphologies have been identified each type of crystal has a specific origin the m micro rods are physicochemical nuclei or calcified bacteria they do not seem to evolve towards larger or more complex morphologies the ma rods are related to biomineralization inside the fungal sheaths the mb rods postdate liberation of ma rods from mycelian bundles the serrated plates are secondary syntactic crystallizations of physicochemical origin whose growth can be inhibited for various reasons the origin of p chains is less well understood but they seem to be physicochemical crystallizations related to evaporation and desiccation therefore these three groups m ma mb and p have similar morphologies but do not seem to be related genetically the only known link is between the ma and mb rods there is no evolutionary s quence of needle fiber calcite habits but a convergence of forms between crystals whose origins are different and independent structures described in the literature as convoluted random cutane and nest like are the result of either evolution of the mycelian bundles or movement of material and organisms in the soil in the case of m micro rods the microfabric is related to the random precipitation around nuclei in pores filled with a highly supersaturated solution initially the p chains also precipitate without preferential organization and later on the growth seems to preferentially constitute chains although the mechanisms are still not understood moreover needle fiber calcites do not indicate a particular climatic environment

pedogenic carbonates on precambrian silicate rocks in south india origin and paleoclimatic significance abstract calcrete in alfisols on precambrian silicate rocks is studied here in an attempt to reconstruct paleorainfall trends in semiarid south india facies of observed carbonate accumulation are pseudomycelium calcrete nodules nodular horizons hardpan and laminar horizons based on geochemical and sr isotope tracing we relate the presence of calcrete to local geologic conditions within the precambrian basement notably discrete ca rich metamorphic outcrops and rule out eolian input micromorphologic analysis reveals a multi stage origin of the calcretes involving soil colluvial geochemical and biologic processes mostly in vadose environments preliminary u th ages of 190 200 ka obtained on calcrete nodules suggest a major phase of ca release rock weathering and precipitation during marine oxygen isotope stage 7 the calcrete thus indicates fairly stable semiarid conditions at the 200 ky time scale despite fluctuations around an annual rainfall average close to current values 700 mm the stability of the western ghats barrier as a shield to the southwest monsoon explains the long term average stability of the pedoclimatic environment in the rainshadow zone the radiometric ages suggest that weathering may occur massively at discrete intervals of geologic history during spikes of humidity in the paleoclimatic record the rest of the time is spent recycling and redistributing the products of weathering incrementally at landscape scale within seasonal cycles of a relatively stable semi arid climate dating the calcrete therefore does not equate with dating the soil but instead the residence times of nodules in a dynamic soil system in which different constituents have different turnover rates

soil formation on calcium carbonate rich parent material in the outer carpathian mountains a case study abstract in this study ten stratified calcium carbonate rich soil profiles from the polish outer carpathians were investigated in order to identity the influence of parent material variability and slope processes on soil diversity and their evolution moreover we evaluated the morphological and physico chemical soil properties to recognize the diagnostic horizons and classification of such soils while it is usually thought that carbonate rich soils are considered as formed in situ these study soils clearly presented layering and contribution of materials as they were developed from mixed substrates of different origin e g as the result of mass movements and possible aeolian silt contribution irrespective of the type of parent material every investigated soil showed traces of slope processes resulting in heterogeneous soil profiles further a few different patterns of primary calcium carbonate arrangement were found in general the studied soils were characterized by enrichment with calcium carbonate not only due to inheritance from calcium carbonate rich parent material but also translocation of calcium carbonate within soil profiles the latter depending on soil stratification based on the obtained results four pathways of soil evolution were formulated leptosols which represent initial calcium carbonate rich soils may evolve in different directions first formation of the thick layer suitable for cambic horizon development under deciduous forests which enables the classification of such soils as cambisols depends on slope processes and allochthonous material deposition in turn the decrease of mineralization rates for organic matter delivery of soil material from the upper parts of the slope as well as mixing of organic matter by mesofauna result in the formation of mollic horizons and transformation of leptosols into phaeozems further erosion and redeposition of fine soil material provide two types of slope sediments i those with silt loam texture dominance and ii clay loams interstratified with silty substrates the first type of sediments are more suitable for water percolation and after carbonate leaching clay dispersion and translocation occur in such materials luvisols may develop sediments with a prevalence of clay loam aided stagnosol formation in which pools of carbonates were stabilized due to the reduction of water percolation leading to stagnation

radiocarbon dating of thin pedogenic carbonate laminae from holocene archaeological sites radiocarbon dating has been previously suggested to be applicable to pedogenic carbonate however until now the validity of radiocarbon dates from pedogenic carbonate remained poorly understood because of the relatively low resolution of chronological controls in this study we compared the radiocarbon dates a total of 21 of thin 0 2 0 3 mm in thickness laminae of pedogenic carbonate coatings on clasts from holocene archaeological sites in the eastern mediterranean and south siberia with independently estimated age ranges for these sites we obtained a high correlation between the oldest laminae of coatings with the site ages the 14 c ages of pedogenic carbonate were systematically younger by c 0 3 1 6 ka mean c 0 75 ka compared with archaeological sites this finding suggests that pedogenic carbonate despite potential complicating factors can be dated more accurately with 14 c than has been generally appreciated

u series dating of impure carbonates an isochron technique using total sample dissolution abstract u series dating is a well established technique for age determination of late quaternary carbonates materials of sufficient purity for nominal dating however are not as common as materials with mechanically inseparable aluminosilicate detritus detritus contaminates the sample with extraneous th we propose that correction for contamination is best accomplished with the isochron technique using total sample dissolution tsd experiments were conducted on artificial mixtures of natural detritus and carbonate and on an impure carbonate of known age results show that significant and unpredictable transfer of radionuclides occur from the detritus to the leachate in commonly used selective leaching procedures the effects of correcting via leachate residue pairs and isochron plots were assessed isochrons using tsd gave best results followed by isochron plots of leachates only

development of quaternary calcrete in the tensift al haouz area central morocco characterization and environmental significance abstract this study utilizes features of calcrete to elucidate the main environmental factors that affect its formation and distribution in the tensift al haouz area central morocco one of semi arid regions where calcrete is ubiquitous and occurs in a variety of forms more than hundred calcretes profiles were examined and described by field observations selected samples were analyzed by optical microscopy om scanning electron microscopy sem x ray diffraction xrd and chemical analysis xrf two types of evolution and genesis are evidenced 1 calcrete of pedogenic origin in the central and eastern part of the studied area developed in the vadose zone with an upward gradational maturity pattern ranging from incipient nodular to concretionary and to hardpan 2 combination of groundwater and pedogenic origin in the western part the paired calcrete profiles consist from bottom to top of massive calcrete suggested to have a groundwater origin it might be formed under wet to semi arid climatic conditions and the gravel hardpan situated at the top suggested to have developed in the vadose zone by pedogenic processes under arid climate in this study we conclude that the vertical and lateral distribution of calcrete is related to differences in the topography the nature of the bedrock the texture of parent material and the climate

clay transformation and pedogenic calcite formation on a lithosequence of igneous rocks in northwestern iran abstract knowledge about the pathways of pedogenic calcite formations and clay transformations on igneous rocks in semiarid regions plays a vital role in the commentary of soil development on these rocks the present study was conducted to explore the weathering stages and pathways for the formation of pedogenic calcite in soils developed on selected plutonic and volcanic rocks in a semiarid climate in north western iran the soils developed on plutonic rocks were found to be in the primary stage of weathering with very few pedogenic calcites except for soil developed on alkali granite which contained few calcitic pedofeatures calcitic crystallitic b fabrics and calcitic pedofeatures were found in all soils developed on volcanic rocks in situ weathering of ca bearing minerals such as plagioclases amphiboles and pyroxenes could be the possible explanation for the accumulation of pedogenic calcite in the absence of calcareous parent rocks in the studied area micritic calcite was observed to be the dominant form in most of the soils developed on volcanic rocks indicating a rapid precipitation of calcium carbonate smectite kaolinite and mica illite were present in the soils developed on plutonic rocks and the clay content in these soils was less than that of the volcanic rocks feldspars plus mica were supposed to be the most likely source minerals for the formation of pedogenic illite which could be consequently transformed into smectite in these semi arid environments smectite mica illite and kaolinite were the most abundant clay minerals in the soils developed on dacite and andesite rocks while a minor quantity of vermiculite occurred only in andesite derived soils smectite as the dominant mineral and some kaolinite with fairly constant variation in content with depth were observed in the soils formed on hornblende andesite and pyroxene andesite this could indicate that the smectite had the authigenic origin and was formed most likely from the weathering of plagioclase hornblende and pyroxene in general in situ crystallization of pedogenic carbonates and high quantities of smectite in the clay fraction confirmed that the soils formed on volcanic rocks were more developed than those on plutonic rocks in the studied semiarid region moreover our results showed that releasing calcium from ca bearing minerals in igneous rocks in conjunction with biological activities resulted in pedogenic calcite formation

evaluation of tsunami flooding using geomorphologic evidence abstract whatever the generating mechanism of a tsunami may be this event can discharge destructive energy along coastal areas and produce widespread inundation the presence of large boulders along rocky coasts could be a useful indicator to understand the extent of the impact of past tsunami floods a detailed study of the deposited boulder features size shape and rock density and their initial position prior to the transport is extremely important when reconstructing the possible morphodynamic scenario s applying the appropriate equations is important when aiming to assess the maximum extent of flooding the integration of morphological and hydrodynamic data allows for an estimation of the water level during the tsunami event responsible for boulder transport moreover it is possible to calculate how far the impacting wave flooded inland this is a function of the wave parameters and of the degree of roughness of the flooded terrain that is expressed by the manning number to evaluate its probable average value experimental data computer simulations and post tsunami surveys have been performed in two sectors of the southern apulia coastline characterised by the presence of tsunami boulder fields and or ridges the surveys in each site have allowed for the calculation of the boulder sizes the estimation of their pre transport location and the extent of inland flooding data have been processed using a geographic information system gis as a result a flooding map useful in planning future possible actions for coastal area use has been produced

shaking scenarios from multiple source models shed light on the 8 september 1905 mw 7 calabria earthquake southern italy project istege indagine sismotettonica del terremoto dell 8 settembre 1905 mw 7 4 nel golfo di sant eufemia offshore tirrenico calabrese supported by ogs istituto nazionale di oceanografia e di geofisica sperimentale project ritmare funded by dipartimento della protezione civile italy s national civil protection

denudation history of the continental margin of western peninsular india since the early mesozoic reconciling apatite fission track data with geomorphology a comprehensive apatite fission track aft study of the passive margin of western peninsular india between 12 and 16 n is used to reconstruct the denudation chronology of the continental hinterland in common with other rifted margins the morphology is characterised by a low lying coastal plateau separated from an elevated inland plateau by an erosionally controlled escarpment western ghats we modelled the fission track data using the commonly adopted annealing algorithm of laslett et al chem geol 65 1987 1 13 using the default parametrisation i e an initial track length of 16 3 m it was found that during the mesozoic denudation rates remained extremely low increasing sporadically when erosion peaked at 130 ma rifting with antarctica and 80 ma rifting with madagascar denudation rates rose considerably during the cenozoic reaching maxima of ca 120 m myr such values are however considered as major overestimates and the effects of the seychelles rifting at 65 ma remain suspiciously unrecorded we explored the consequences of changing the initial track length in this model to a value of 14 5 m in practice this reduces the rapid cenozoic denudation artefact model peak rates during the mesozoic are much more variable and during the cenozoic reach values an order of magnitude lower than with the original initial track length the response to the seychelles rifting event is almost immediate just as previous model calibrations in aft analysis have been relatively empirical this revised approach does not provide insights into the physical mechanisms of low temperature annealing however it is shown to agree much better with independently established geomorphic cosmogenic stratigraphic and tectono magmatic evidence in this and other stable shield regions in terms of both the timing and the magnitude of geological events and the geomorphic response of the landscape to them

systematics of u th disequilibrium in calcrete profiles lessons from southwest india pedogenic carbonates calcretes have often been proposed as possible markers of the pedogenetic processes in soils under semi arid climate however precise chronological constraints on their formation are required in order to investigate the climatic and paleo environmental conditions that prevailed during and after their formation and to improve our understanding of the physical and chemical conditions that promoted their development and preservation moreover these authigenic calcium carbonate precipitates provide us with an interesting test of the u th radioactive disequilibrium dating method the reliability of which has been demonstrated extensively in aragonitic corals and calcitic continental speleothems but which remains much more questionable in highly porous chemically and mineralogically complex media such as soil profiles we report here 238u 234u 230th radioactive disequilibrium analyses measured by thermo ionization mass spectrometry in calcretes from two sites in southwest india since calcretes are impure carbonates mixed with various amounts of parent rock and weathered minerals all ages must be computed using the isochron technique involving the extraction of several coeval subsamples from the same soil horizon and u th analyses after total dissolution tsd method in order to correct for the detrital component 232th is usually used as index of the detrital contamination and the isochron age is derived from the isotopic composition 230th 238u 234u 238u of the pure authigenic carbonate end member of the mixing line our results show that each set of samples taken from decimetric blocks is characterized by a well defined isochron line in a 3 d osmond diagram 232th 238u 230th 238u 234u 238u the regression lines obtained for most of the samples show probabilities of fit satisfying the mathematical assumptions of the isochron model in most cases 0 05 and mean square weighted deviations mswd values around 1 the compositions of the end members are highly variable between the different isochrons both for the carbonate phase indicating various ages of cristallisation and for the detrital phase indicating various origins and compositions notably our data demonstrate that the detrital component is in all cases out of secular equilibrium by contrast with the standard paradigm of dirty carbonate dating which is based on the assumption of average continental crust th u elemental ratio and secular equilibrium values of the 230th 238u and 234u 238u ratios at the first site coimbatore we obtain u th ages between 304 38 ka and 44 2 9 ka 2 from the base to the top of the profile these suggest discontinuous precipitation of the different facies in good agreement with micromorphological observations at the second study site gundlupet the carbonate nodules sampled from two different profiles yield consistent ages of 200 ka which suggests that precipitation of nodular carbonate occurred across the entire pediment toposequence during a single event surprisingly in mere contradiction with the standard model of impure carbonate dating two puzzling samples display vertical isochrons i e variable 232th 238u without any variation of the 230th 238u and 234u 238u ratios such patterns require extremely high 232th 238u ratios in an as yet unidentified detrital phase taken at face value these results suggest that no clear correlation can be inferred between the precipitation of these pedogenic carbonates and major orbitally driven climate variations recorded in other archives during the last glacial interglacial cycles

the capo vaticano calabria coastal terraces and the 1905 m7 earthquake the geomorphological signature of regional uplift and coseismic slip in southern italy terra nova 22 378 389 2010 abstract the elevation of the capo vaticano coastal terraces tyrrhenian coast central calabria is the result of a combination of regional uplift and repeated coseismic displacement we subtract the regional uplift from the total uplift maximum average uplift rates 0 81 0 97 mm a 1 since c 0 7 ma and obtain the residual fault related displacement then we model the residual displacement to provide constraints on the location and geometry of the seismogenic source of the 1905 m7 earthquake the strongest and still poorly understood earthquake of the instrumental era in this area we try four different potential sources for the dislocation modelling and find that 1 three sources are not compatible with the displacement observed along the terraces and 2 the only source consistent with the local deformation is the 100 striking coccorino fault we calculate average long term vertical slip rates of 0 2 0 3 mm a 1 on the coccorino fault and estimate an average recurrence time of one millennium for a 1905 type earthquake

distribution of calcrete in holocene coastal sands in relationship to climate southwestern australia seven study areas located over 320 km of coastal plain in southwestern australia show the distribution of groundwater and vadose calcrete within holocene coastal sands age 7 100 yr bp over a regional climate gradient the calcrete exhibits a range of structures that include rhizoconcretionary mottled massive and laminar types groundwater calcrete composed of mottled massive and laminar types occurs as a thin sheet in the zone of capillary rise just above the water table vadose calcrete is predominantly rhizoconcretionary at all sites where it is well developed the groundwater and vadose calcretes are closely associated with vegetation calcrete is well developed in southern areas that are humid further north as the rainfall decreases and evaporation increases calcrete is less common until it is absent or rare at the semiarid northern limit of the study region its limit of occurrence is correlated with a region whose rainfall is ca 800 mm annum evaporation is ca 1 900 mm annum and mean summer temperature is 23 degrees c this study shows therefore that a trend toward a drier climate may not be conducive to the development of calcrete although such a view prevails in the literature

seismicity and p wave velocity image of the southern tyrrhenian subduction zone summary this paper focuses on the deep earth structure and earthquake distribution within the southern tyrrhenian subduction zone we discuss seismological observations which provide insight into the mechanics of subduction processes for an unusual compressional margin the motivation for this work derives from the recognition that little is known about one of the most intriguing geodynamic features of the italian peninsula and the fact that a large amount of information can be extracted from data collected by the istituto nazionale di geofisica national seismic network we show that the hypocentres of intermediate and deep earthquakes that have occurred since 1988 image a nw dipping plane continuous from the ionian sea to the tyrrhenian down to 450 km depth we also present a 3 d model of the deep structure beneath southern italy derived using deep earthquake seismic tomography tomographic images reveal a high velocity body dipping from the apulian and iblean forelands towards the tyrrhenian basin in the crust and upper mantle at least down to 320 km depth this high velocity body may be related to the cold subducted ionian lithosphere earthquake hypocentres are confined within the high velocity body delineating the subduction beneath the calabrian arc

characterization of groundwater chemistry under the influence of lithologic and anthropogenic factors along a climatic gradient in upper cauvery basin south india hydrogeological and climatic effect on chemical behavior of groundwater along a climatic gradient is studied along a river basin semi arid 500 800 mm of mean annual rainfall sub humid 800 1 200 mm year and humid 1 200 1 500 mm year are the climatic zones chosen along the granito gneissic plains of kabini basin in south india for the present analysis data on groundwater chemistry is initially checked for its quality using nicb ratio 40 of pollution and eliminated for the characterization piper s diagram with mean concentrations indicates the evolution of canahco3 semi arid from cahco3 humid zone along the climatic gradient carbonates dominate other anions and strong acids exceeded weak acids in the region mule hole sew an experimental watershed in sub humid zone is characterized initially using hydrogeochemistry and is observed to be a replica of entire sub humid zone with 25 wells extension of the studies for the entire basin 120 wells showed a chemical gradient along the climatic gradient with sub humid zone bridging semi arid and humid zones ca na molar ratio varies by more than 100 times from semi arid to humid zones semi arid zone is more silicaceous than sub humid while humid zone is more carbonaceous ca cl 14 along the climatic gradient groundwater is undersaturated humid saturated sub humid and slightly supersaturated semi arid with calcite and dolomite concentration depth profiles are in support of the geological stratification i e 18 m of saprolite and 25 m of fracture rock with parent gneiss beneath all the wells are classified into four groups based on groundwater fluctuations and further into deep and shallow based on the depth to groundwater higher the fluctuations larger is its impact on groundwater chemistry actual seasonal patterns are identified using recharge discharge concept based on rainfall intensity instead of traditional monsoon non monsoon concept non pumped wells have low na cl and ca cl ratios in recharge period than in discharge period dilution few other wells which are subjected to pumping still exhibit dilution chemistry though water level fluctuations are high due to annual recharge other wells which do not receive sufficient rainfall and are constantly pumped showed high concentrations in recharge period rather than in discharge period anti dilution in summary recharge discharge concept demarcates the pumped wells from natural deep wells thus characterizing the basin

high resolution morpho bathymetric imaging of the messina strait southern italy new insights on the 1908 earthquake and tsunami the 28 december 1908 reggio calabria and messina earthquake named after the two most damaged cities on the coasts of messina strait was one of the strongest mw 7 1 ever to occur in italy and was also followed by a tsunami that severely impacted the coasts of the strait although there is general agreement that its epicentre is located offshore in the messina strait the source fault has never been detected a century long question is therefore pending on the source of both the 1908 earthquake and tsunami within the ongoing debate on this subject little attention has been given so far to morphological insights from high resolution bathymetric multibeam data particularly as regarding the evidence of faults affecting the seafloor and the question of whether a submarine landslide may had been the cause of the tsunami we aim to address this issue by presenting the results of a morpho bathymetric study in the messina strait and surroundings investigated by means of high resolution swath bathymetry the primary morpho structural feature in this area is the axial channel of the messina canyon towards which flow several tributary canyons that incise the steep continental slope on the calabrian and sicilian margins these canyons carve deeply into a very narrow almost lacking continental shelf and merge laterally forming a continuous erosional margin rimming the messina strait this giant composite canyon environment is the locus of intense erosional and depositional processes that superimpose on active tectonic deformation resulting in a complex geomorphology that hinders the distinction between tectonic and sedimentary features seafloor ruptures that may be linked to fault systems compatible with the source of the 1908 earthquake and tsunami could not be identified based from our morpho bathymetric analysis however we provide evidence of several geomorphic features indicative of tectonic deformation in the messina strait define the presence and distribution of submarine landslides and evaluate their possible role as tsunami sources

evidence of vertical tectonic uplift at briatico calabria italy inferred from roman age maritime archaeological indicators abstract calabria is one of the most complex geological regions of the mediterranean basin which experienced large earthquakes and uplift and is still undergoing active tectonics along its coasts are located archaeological sites that can be used as powerful indicators of the relative vertical movements between land and sea since their construction this paper presents and discusses data on the relative sea level change as estimated from maritime archaeological indicators of the last 2 0 ka bp existing along the tyrrhenian coast of briatico these sites still show the remnants of a roman age fish tank and a submerged breakwater about 320 m long the palaeo sea level has been obtained measuring the functional elevation of the significant archaeological markers their elevation was compared against the latest predicted sea level curve for the holocene along the tyrrhenian coast of calabria as this coastal area is affected by significant and continuous vertical tectonic uplift during pleistocene the data show the counterbalance between coastal uplift and relative sea level change caused by the glacio hydro isostasy acting since the construction of these archaeological sites the sum of these movements determined an about null relative sea level change for this location these data are in contrast with other part of the tectonically stable areas of the mediterranean and provide evidence that crustal uplift continued in the last 1806 50 y at a rate of 0 65 mm y

atmospheric input vs in situ weathering in the genesis of calcretes an sr isotope study at galvez central spain strontium isotopes have been analyzed in a typical calcrete profile developed on granite in the toledo mountains central spain the pedogenic carbonates show clear petrographic evidence of pseudomorphic replacement of the weathered parent granite calcretes display 87sr 86sr ratios between 0 70961 and 0 71059 in sharp contrast to the granite whole rock 0 72856 and minerals 0 71359 to 0 91351 this difference shows that the contribution of sr from the granite to the calcretes is at most 33 and may be as low as 3 direct measurements in rains and aerosols show that the allochtonous source of ca and sr is clearly related to the atmospheric input mainly as dry deposit a slight decrease of sr concentration is observed from the upper horizon composed of continuous calcrete to the deeper calcrete veins in the saprolite this may be due to a kinetic control of the sr ca fractionation and different crystallization rates of the carbonates in the different units of the profile finally local groundwaters have sr isotopic compositions similar to the calcretes and the atmospheric input very different from waters running on the granite

recent and active tectonics in the calabrian arc southern italy normal faulting which has developed since the middle pleistocene with an overall ese wnw extension is the dominant mode of deformation which has characterized the calabrian arc up to the present quaternary normal faults extend for a total length of about 180 km along the inner side of the arc the different normal fault segments which during the pleistocene controlled the evolution of the main marine sedimentary basins are varying in length from 10 to 20 km and have fault escarpments showing a very young morphology which define the fronts of the major mountain ranges of the arc the morphological features of the fault escarpments suggest slip rates of 0 8 1 1 mm yr for the last 700 k y and values of 0 6 0 9 mm yr for the last 120 k y indicating a uniform rate of faulting since the middle pleistocene crustal seismicity and the mesoseismic areas of historical large events 6 5 m 7 1 which occurred in the calabrian arc are located within a narrow belt along the hanging walls of the quaternary normal fault segments this suggests that the normal faults which dissect the inner side of the calabrian arc may be seismically active

tsunami taxonomy and detection from recent mediterranean tide gauge data abstract sea level records collected in digital form with high sampling rate by recently upgraded tide gauges located along the mediterranean coasts are subjected to a posteriori investigation to examine and characterize occurrence of sea level oscillations in the tsunami period range induced by both underwater or coastal earthquakes and by meteorological events after performing a rigorous quality control procedure on the raw sea level time series a wavelet based analysis is applied to 2 h high pass filtered data to identify oscillations generated by earthquakes and a few events are modeled aiming to verify travel time and expected spectral shape seismic tsunami oscillations that are not reported in published catalogues are identified in the sea level records of the period 2010 2014 just after three different earthquake events a method is proposed to detect occurrence of tsunami like oscillations of meteorological origin from the available tidal records based on the distribution of the detided level process over spectral bandwidth parameter and mean period the developed methodology is also the first presented which allows to distinguish sea wave induced harbor seiches from fluctuations of meteorological origin associated with passage of atmospheric disturbances meteotsunamis in sea level time series the results of the analyses show that during the considered period in the mediterranean sea tsunamis of seismic origin are rare and weak meteotsunamis on the contrary are relatively frequent and in critical areas may reach intensities exceeding astronomical tide the availability of the recently acquired high frequency records and the presented approach allow to extend the list of recorded tsunami events of both seismic and meteorological origin the identified event sets may be used for improved hazard analyses and risk assessments along the mediterranean coasts

isotopic tracers of the origin of ca in a carbonate crust from the middle atlas morocco abstract carbonate crusts developed on basalt were studied at tazouta in the moroccan middle atlas the chosen representative weathering profile is 2 8 m thick and is composed from base to top of a fresh basalt overlain by a coherent saprolite a friable saprolite and a surface soil carbonate crust genesis occurs by replacement of primary and secondary clay minerals by low mg calcite the 14 c dates of the calcite range from 15 to 14 ka in the coherent saprolite and from 12 to 8 5 ka in the friable saprolite smectitic weathering and replacement of si bearing minerals by carbonate are coupled processes leading to a strong calcium net gain 300 kg m 3 within the friable saprolite the low weathering rate of basalt compared to the calcrete genesis rate and the high mobility of calcium in supergene weathering mantles limit the basaltic ca contribution to calcrete genesis the contribution of the triassic sediment is also limited by the mineralogical unavailability of ca the 87 sr 86 sr ratios confirm the low contribution of basalt and indicate an external origin of ca the sr isotope ratios of calcrete are different from those of the adjacent liassic carbonates and are close to rainfall values the carbon isotope compositions of carbonates 8 to 9 vs pdb imply a significant contribution of c3 dominated organic carbon during carbonate precipitation oxygen isotopic compositions of carbonates average 5 24 vs pdb show that carbonates are 18 o enriched compared to meteoric waters 4 to 3 5 vs smow

the generating mechanisms of the august 17 1999 izmit bay turkey tsunami regional tectonic and local mass instabilities causes abstract the m w 7 4 earthquake that affected the northwestern part of turkey on august 17 1999 and in particular the gulf of izmit had dramatic consequences also as regards tsunami generation the main cause of the earthquake was a dextral strike slip rupture that took place along different segments of the western part of the north anatolian fault wnaf the rupture process involved not only a number of distinct strike slip fault segments but also dip slip ancillary faults connecting the main transcurrent segments the general picture was further complicated by the occurrence of subsidence and liquefaction phenomena especially along the coasts of the izmit bay and in the sapanca lake tsunami effects were observed and measured during post event surveys in several places along both the northern and the southern coasts of the bay the run up heights in most places were reported to lie in the interval 1 3 m but in the small town of degirmendere where a local slump occurred carrying underwater buildings and gardens of the waterfront sector eyewitnesses reported water waves higher than 15 m the purpose of this work is to investigate on the causes of the tsunami by means of numerical simulations of the water waves we show that the tsunami was a complex event consisting at least of the combination of a regional event due to tectonic causes and of a local event associated with the mass failure as to the first we are able to demonstrate that the observed tsunami cannot be explained only in terms of the sea bottom dislocation produced by the main right lateral dislocation but that the prominent contribution comes from the displacement associated with the secondary shallow normal faults furthermore the large waves and effects seen in degirmendere can be explained as the consequence of the slump by means of a stability analysis based on an original method making use of the limit equilibrium concept we show that the slump was highly stable before the earthquake and that it was triggered by seismic waves simulation of the tsunami induced by the slump was carried out by a two step numerical code that computes the landslide motion first and then the generated water wave propagation it is shown that the computed local tsunami matches the experimental data

estimation of weathering rates and co2 drawdown based on solute load significance of granulites and gneisses dominated weathering in the kaveri river basin southern india abstract the solute load of the kaveri river south india and its tributaries draining diverse precambrian terrains during pre monsoon and monsoon periods was determined using average annual flow total drainage area and atmospheric input corrected major ion concentrations of these rivers chemical weathering rates annual fluxes of different ionic species to the ocean and co2 consumption rates were estimated bicarbonate is the most dominant ion 27 79 of anion budget in all the river samples collected during monsoon period followed by ca2 whereas in case of pre monsoon water samples na is the most dominant ion in meq l two approaches were adopted to estimate silicate and carbonate weathering rates in the drainage basin at musuri silicate weathering rate swr is 9 44 0 29 tons km2 a and carbonate weathering rate cwr is 1 46 0 16 tons km2 a more than 90 of the total ionic budget is derived from weathering of silicates in the kaveri basin co2 consumption rate in the basin for silicate weathering f co 2 sil is 3 83 0 12 105 mol km2 a upper limit which is comparable with the himalayan rivers at upper reaches for carbonate weathering f co 2 carb co2 consumption rate is 0 15 0 03 105 mol km2 a in the kaveri basin the lower limit of co2 consumption rate corrected for h2so4 during silicate and carbonate weathering is f co 2 sil is 3 24 1005 mol km2 a and f co 2 carb 0 13 105 mol km2 a respectively co2 sequestered due to silicate weathering in the kaveri basin is 25 41 0 82 109 mol a which represents 0 21 0 01 of global co2 drawdown this may be due to tropical climatic condition high rainfall during both sw and ne monsoon and predominance of silicate rocks in the kaveri basin

a rock magnetic record of pleistocene rainfall variations at the palaeolithic site of attirampakkam southeastern india abstract attirampakkam an open air stratified palaeolithic site in southeastern india is the focus of ongoing studies to investigate the nature of lower and middle palaeolithic occupation in relation to changing pleistocene environments the paucity of faunal or palaeobotanical remains at the site required the use of rock magnetic properties lf fd fd arm sirm arm sirm sirm lf arm lf arm fd s ratio hirm and hirm irm 300mt as proxies for deciphering the palaeoenvironments and palaeoclimates of the region rock magnetic data from stratified deposits within excavated trenches show that the bulk of the sedimentation was intermittent with no subaerial exposure of sediments for long periods and points to fluctuating wetter and drier climates associated with the acheulian to late middle palaeolithic levels there is a general trend towards a wetter climate from layer 5 upwards layer 7 offers evidence of bacterial magnetite arm lf 40 and arm fd 1000 suggesting the onset of micro anaerobic environments as a result of floods greigite is indicated in layer 5 sirm lf 30 10 3 a m 1 which indicates a reducing environment layer 2 represents an arid climate higher proportion of haematite and a coarser magnetic grain size layer 1a again is indicative of an arid climate presence of calcrete magnetically hard minerals and coarser magnetic grain size results indicate that the southeast coast of india experienced a mostly dry tropical climate during the pleistocene the detected occurrence of a few notably more arid intervals did not disrupt occupation of the site by successive groups of hominins

a holocene calcrete from north yorkshire england implications for interpreting palaeoclimates using calcretes glacial gravels of late devensian dimlington stadial age 26 000 13 000 years bp at west tanfield north yorkshire england have been cemented by carbonate rich solutions to produce a strongly indurated calcrete horizon the low mg cements occur as drusy spar needle fibres alveolar septal structures micrite and micropinnacles indicative of vadose zone cementation some complex pore partition structures attributed to precipitation along meniscus films also occur these partitions separate air dominated and water dominated microenvironments of the vadose zone the abundance of vadose fabrics shows that the accumulation is not a groundwater calcrete in addition much of the carbonate appears to have been precipitated by biological mediation carbon and oxygen isotopic data suggest that the carbonate did not form as a result of freezing as has been suggested for some arctic soil carbonates the pollen history of the area since the devensian suggests that this calcrete precipitated at low temperatures this contrasts with widely reported occurrences of calcrete in soils of hot arid or semi arid regions and suggests that palaeo calcretes should not be used as absolute palaeoclimatic indicators the unusual occurrence albeit localized of a thick calcrete under a cool and wet climate probably reflects the well drained nature of the gravels the abundance of caco3 as limestone clasts in the gravel and a high degree of biological activity beneath a forest cover which created a local environment favouring carbonate precipitation