deterioration of stone materials in the angkor monuments cambodia the angkor monuments in cambodia are built mainly of sandstone and laterite this paper mainly describes the deterioration of sandstone blocks the sandstone in the monuments can be classified into three types based on the colour texture chemical composition and constituent mineral grey to yellowish brown sandstone red sandstone and greenish greywacke the deterioration is distinct in grey to yellowish brown sandstone because of its low compressive strength high porosity well developed bedding and constituent minerals susceptible to alteration such as feldspar and biotite the main causes of deterioration identified are chemical weathering efflorescence related to bat guano and biodeterioration by the growth of trees algae and lichens an water supply is also indispensable for deterioration

influence of syn sedimentary faults on orogenic structures in a collisional belt insights from the inner zone of the northern apennines italy abstract this paper discusses the possible influence of syn sedimentary structures on the development of orogenic structures during positive tectonic inversion in the inner northern apennines italy examples from key areas located in southern tuscany provided original cartographic structural and kinematics data for late oligocene early miocene thrusts organized in duplex systems verging in the opposite direction of the foreland propagation back thrusts which affected the late triassic oligocene sedimentary succession of the tuscan domain previously affected by pre orogenic structures these latter consist of mesoscopic to cartographic scale jurassic syn sedimentary normal faults and extensional structures which gave rise to effective stratigraphic lateral variation and mechanical heterogeneities structural analysis of both syn sedimentary faults and back thrusts were therefore compared in order to discuss the possible role of the pre existing anisotropies in influencing the evolution of the back thrusts as a result it can be reasonably proposed that back thrusts trajectories and stacking pattern were controlled by relevant syn sedimentary normal faults these latter were reactivated in some cases if properly oriented such an issue adds new inputs for discussing the potential role of structural inheritance during tectonic inversions and helps to better understand the processes suitable for the development of back thrusts in the inner zones of orogenic belts as it is the case of the inner northern apennines

three dimensional distribution of minerals in the sediments of hayonim cave israel diagenetic processes and archaeological implications the mineral components of the sediments that accumulate in an archaeological site constitute a potentially rich source of information on the diagenesis and in turn the archaeology of the site this detailed three dimensional study of the mineral assemblages in mainly the mousterian sediments of hayonim cave incorporates more than 2100 infrared analyses performed on site during the excavation as well as diverse analyses in the laboratory three major mineral assemblages are identified the calcite dahllite cd assemblage the assemblage comprising mainly montgomeryite leucophosphite and siliceous aggregates lmvs and a highly altered sediment in which the clays have broken down and silica was released the boundaries between these assemblages were mapped in detail the overall picture is one of extreme heterogeneity with sharp variations occurring over distances of a few centimetres the relation between the cd and lmvs assemblages shows that it is a product of post depositional diagenesis whereas the altered clay assemblage formed beneath an erosional unconformity the cd and lmvs assemblages were derived primarily from an accumulation several metres thick of ash deposits produced by humans ash is thus shown to be a major component of the sediments of this cave the distribution of the cd assemblage reflects to a large extent the locations of two active springs seepages in the cave the distribution of the cd assemblage also faithfully maps the distribution of bones in the cave showing that their distribution is a function of preservational conditions and not human activities stineret al 2001 the conditions that produced the erosional unconformity also resulted in severe alteration of the clays and other mineral components of these sediments the erosion process and the fact that the thickness of this altered zone decreases towards the centre of the cave indicates that the diagenetic driving force was probably climatic the three dimensional distributions of the mineral assemblages have a direct bearing on the dating of the cave by thermoluminescence and electron spin resonance

ash deposits in hayonim and kebara caves israel macroscopic microscopic and mineralogical observations and their archaeological implications abstract a study of the hearths and ash layers preserved in hayonim and kebara caves israel showed that they are composed of one or several different minerals these include the polymorph of caco3 calcite a variety of phosphate minerals and a suite of siliceous minerals the major component of the latter are siliceous aggregates that are present in wood detailed studies of the mineral associations in these fossil ash layers as well as in fresh wood ash using optical and scanning electron microscopy in the back scattered electron mode together with elemental analyses showed that ash in these caves undergoes a series of diagenetic changes the best preserved ash layers resemble fresh ash and are composed mainly of calcite with minor amounts of siliceous minerals the calcite reacts with phosphate rich solutions to form carbonated apatite and with time the latter dissolves and a variety of other phosphate containing minerals form with each diagenetic change some of the more soluble minerals are lost and ultimately only the ash derived siliceous minerals remain in both caves there are local accumulations of such siliceous minerals that are metres thick in fact ash derived minerals in general are major components of the sediments in both kebara and hayonim caves their diagenesis involves a hugh reduction in volume which in turn may have important effects on the geological structures and stratigraphy of the sediments the changing mineralogy of the sediments due to diagenesis complicates the use of present day estimates of radiation content of the sediments for correcting age estimates by thermoluminescence and electron spin resonance finally the presence of the relatively stable ash derived siliceous minerals in a sedimentary layer in other caves could be a useful means of identifying the presence of ash in other archaeological sites where macroscopic hearth features are absent

dating of deformation phases using k ar and 40ar 39ar techniques results from the northern apennines abstract paleozoic to oligocene metasedimentary rocks present in the alpi apuane region of the northern apennines italy have been sequentially deformed during a tertiary progressive deformation in an attempt to date the individual deformation episodes over 50 conventional k ar and 1140 ar 39ar incremental gas release analyses have been carried out on fine grained white micas separated from samples whose structural settings were well known mineralogy x ray diffractometry and thin section analyses indicate that the constituent muscovite and phengite formed under metamorphic conditions of 3 4 kbars and 300 400 c during all deformational phases pre existing micas were variably crenulated during each subsequent deformational phase both k ar and 40ar 39ar analyses were carried out on 0 6 2 m 2 6 m and 6 20 m size separates of the phengitic white mica although the k ar apparent ages range from 11 to 27 ma and are consistent with available stratigraphic constraints the 40ar 39ar age spectra display variable internal discordancy these isotopic data indicate that 1 both the k ar and 40ar 39ar total gas ages decrease as the degree of crenulation increases 2 the k ar and 40ar 39ar total gas ages decrease as grain size decreases 3 for each sample characteristics of the 40ar 39ar age spectra depend upon grain size with fine sizes yielding discordant patterns which systematically increase in apparent age from low to high temperature and 4 phengitic micas associated with earliest structures yield generally older ages than micas associated with later structures the isotopic results are interpreted to indicate that the major deformation phase d1 occurred at approximately 27 ma with subsequent pulses ending by c 10 ma these results may be combined with finite strain data to suggest that the region was deformed at strain rates between 10 15 and 10 14 s 1 a 27 ma age indicates mid oligocene initiation of plate tectonic activity in the western mediterranean and concomitant deformation in the northern apennines

long wave resonance in tropical oceans and implications on climate the atlantic ocean based on the well established importance of long non dispersive baroclinic kelvin and rossby waves a resonance of tropical planetary waves is demonstrated three main basin modes are highlighted through joint wavelet analyses of sea surface height ssh and surface current velocity scv scale averaged over relevant bands to address the co variability of variables 1 a 1 year period quasi stationary wave qsw formed from gravest mode baroclinic planetary waves which consists of a northern an equatorial and a southern antinode and a major node off the south american coast that straddles the north equatorial current nec and the north equatorial counter current necc 2 a half a year period harmonic 3 an 8 year sub harmonic contrary to what is commonly accepted the 1 year period qsw is not composed of wind generated kelvin and rossby beams but results from the excitation of a tuned basin mode trade winds sustain a free tropical basin mode the natural frequency of which is tuned to synchronize the excitation and the ridge of the qsws the functioning of the 1 year period basin mode is confirmed by solving the momentum equations expanding in terms of fourier series both the coefficients and the forcing terms the terms of fourier series have singularities highlighting resonances and the relation between the resonance frequency and the wavenumbers this ill posed problem is regularized by considering rayleigh friction the waves are supposed to be semi infinite i e they do not reflect at the western and eastern boundaries of the basin which would assume the waves vanish at these boundaries at the western boundary the equatorial rossby wave is deflected towards the northern antinode while forming the necc that induces a positive doppler shifted wavenumber at the eastern boundary the kelvin wave splits into coastal kelvin waves that flow mainly southward to leave the gulf of guinea in turn off tropical waves extend as an equatorially trapped kelvin wave being deflected off the western boundary the succession of warm and cold waters transferred by baroclinic waves during a cycle leaves the tropical ocean by radiation and contributes to western boundary currents the main manifestation of the basin modes concerns the variability of the necc of the branch of the south equatorial current sec along the equator of the western boundary currents as well as the formation of remote resonances as will be presented in a future work remote resonances occur at midlatitudes the role of which is suspected of being crucial in the functioning of subtropical gyres and in climate variability

modern stable isotopic δ18o δ2h δ13c variation in terrestrial fluvial estuarine and marine waters from north central sarawak malaysian borneo stable isotope data on humid tropical hydrology are scarce and at present no such data exist for borneo delta18o 2h and 13c were analysed on 22 water samples from different parts of the sungai river niah basin rain cave drip rainforest pool tributary stream river estuary sea in north central sarawak malaysian borneo this was done to improve understanding of the modern stable isotope systematics of the sungai niah basin essential for the palaeoenvironmental interpretation of the late quaternary stable isotope proxies preserved in the great cave of niah the niah hydrology data are put into a regional context using the meteoric water line for southeast asia as derived from international atomic energy agency world meteorological organization isotopes in precipitation network data although the niah hydrological data set is relatively small spatial isotopic variability was found for the different subenvironments of the sungai niah basin a progressive enrichment occurs towards the south china sea 18o 4 6 2h 29 3 13c 4 8 from the tributary stream 18o 8 4 2h 54 7 13c 14 5 to up river 18o c 8 2h c 51 13c c 12 and down river values 18o c 7 5 2h c 45 13c c 11 this is thought to reflect differential evaporation and mixing of different components of the water cycle and a combination of depleted biogenic 13c plant respiration and decay with enriched 13c values due to photosynthesis atmospheric exchange mixing with limestone and marine waters downstream cave drip waters are relatively enriched in 13c as compared to the surface waters this may indicate rapid degassing of the cave drips as they enter the cave atmosphere copyright 2005 john wiley sons ltd

correlation between seismic reflectivity and rheology in extended lithosphere southern tuscany inner northern apennines italy abstract in southern tuscany inner zone of the northern apennines the lithosphere has been affected by extensional deformation since the middle miocene and is characterized by high heat flow 120 mw m 2 both local shallow and regional deep seismic reflection profiles clearly show the occurrence of a sharp reflector k horizon within the upper crust which is probably located at the top of a shear zone acting as the decollement horizon for the latest pliocene quaternary normal faults its depth varies between 3 and 6 km in geothermal areas and 9 and 12 km elsewhere borehole control in the geothermal areas shows that it occurs at a temperature of approximately 450 c the hypothesis that the k horizon represents the top of the brittle ductile transition agrees with two lines of evidence a it approximately follows the same isotherm over the whole region and b its depth coincides with rheological predictions of the brittle ductile transition for the range of high pore fluid pressures and strain rates estimated for southern tuscany it appears therefore that at least under specific conditions very high pore fluid pressures strain concentration the brittle ductile transition may have a seismic signature

reconstructing the sedimentary history of lezetxiki ii cave basque country northern iberian peninsula using micromorphological analysis abstract micromorphological analysis is an invaluable research tool for reconstructing detailed depositional and post depositional processes of cave infill sequences and for providing paleoenvironmental insight in this work we present the results of a micromorphological and mineralogical study of the sedimentary sequence at the lezetxiki ii cave northern iberian peninsula the cave forms part of the lezetxiki archaeological complex which has yielded early middle palaeolithic tools and archaic human remains we have identified three main clastic sedimentary processes as being significant at lezetxiki ii 1 fluviokarst or runoff processes which are characterised by yellow sandy illite rich microfacies 2 infiltration processes which produce a massive red silty clay vermiculite rich microfacies and 3 inwash processes which generate a reworked illite and vermiculite rich silty sand microfacies the most common post depositional processes observed are calcite precipitation infilling pore spaces and compression structures derived from specific vertical loading events in order to improve the chronological framework of the sedimentary sequence at lezetxiki ii we have revised previous radiometric and relative dating results from faunal and archaeological remains and have dated the lowermost stratigraphic level using single grain thermally transferred optically stimulated luminescence dating sedimentation at the lezetxiki ii cave started during marine isotope stage mis 7 through fluviokarst processes we interpreted that runoff prevailed during mis 6 while soil infiltration processes became more significant towards the mis 5 optimum gradually inwash processes prevailed over infiltration until the end of the interglacial phase during the following glacial phases runoff and erosion dominated but were subsequently replaced by inwash processes during mis 1

crustal structures in the geothermal areas of southern tuscany italy insights from the crop 18 deep seismic reflection lines abstract two deep seismic reflection lines named crop 18a and 18b and roughly nnw sse oriented were acquired to investigate the crust between the larderello and the mt amiata geothermal areas both located in southern tuscany since the early middle miocene southern tuscany has been affected by extensional tectonics and since the pliocene by widespread magmatism presently extension is demonstrated by ne dipping normal faults and brittle shear zones which affect the crust down to the brittle ductile transition in the larderello area these shear zones are seismically evidenced by ne dipping weak reflections and by the loss of the k horizon reflectivity a regional mid crustal high amplitude reflector located at the top of the brittle ductile transition the crop 18a and 18b lines were reprocessed down to 10 s twt down to the crust mantle boundary their reflectivity results are closely related to the direction of the survey a clear decrease in reflectivity occurs when the survey plane intersects the crustal shear zones along strike nevertheless both lines display segments with low reflectivity and homogeneous acoustic impedance which indicate intrusive magmatic bodies at different crustal levels a wide partially crystallised granitoid may be sited at about 7 8 km depth underneath the larderello geothermal field in the lower part of the crust the crop 18a and 18b transects show group of bright reflections mainly related to the occurrence of pressurised fluids and or lithological differences the base of the crust is located at about 20 km depth

diagenesis in prehistoric caves the use of minerals that form in situ to assess the completeness of the archaeological record an interpretation of the archaeological record in particular that of a prehistoric cave site is complicated by the diversity of depositional and post depositional processes that affect the material deposited here we propose to use the authigenic minerals that form in situ within the cave sediments to reconstruct the ancient chemical environments in the sediments this can be done by experimentally determining the conditions under which each of the authigenic minerals are stable although this information is not available to date for minerals formed in a prehistoric cave we present calculated stability field data for the relevant minerals the results clearly demonstrate the feasibility of this approach this information particularly if based on measurements of real authigenic cave minerals will facilitate an assessment of the completeness of the cave archaeological record this is particularly important for determining whether or not the distributions of archaeologically important materials such as bones teeth plant phytoliths charcoal and ash reflect their original burial distributions or were altered as a result of secondary diagenetic processes

a 50 000 year record of late pleistocene tropical vegetation and human impact in lowland borneo abstract there has been considerable uncertainty about the nature of pleistocene environments colonised by the first modern humans in island se asia and about the vegetation of the last glacial maximum lgm in the region here the palynology from a series of exposures in the great cave of niah sarawak malaysian borneo spanning a period from ca 52 000 to 5000 bp is described vegetation during this period was climate driven and often highly unstable interstadials are marked by lowland forest sometimes rather dry and at times by mangroves stadials are indicated by taxa characteristic of open environments or as at the lgm by highly disturbed rather open forest stadials are also characterised by taxa now restricted to 1000 1600 m above sea level suggesting temperature declines of ca 7 9 c relative to present by comparison with modern lapse rates the practice of biomass burning appears associated with the earliest human activity in the cave

ash bones and guano a study of the minerals and phytoliths in the sediments of grotte xvi dordogne france abstract very few prehistoric cave deposits in western europe contain visible hearth remains even though there is abundant evidence of fire use by cave inhabitants grotte xvi dordogne france is exceptional in this respect in that it contains a most conspicuous layer couche c characterized by a series of brightly coloured bedded sediments the formation of couche c has previously been ascribed to the ash and charcoal produced by the cave s mousterian occupants burning mainly lichens the mousterian sedimentary layers below couche c and the upper palaeolithic sediments unconformably overlying couche c are quite different in texture and colour and show no visible evidence of ash deposits analyses of the minerals microstructures and phytoliths in couche c are consistent with the notion that these sediments were derived mainly from ash produced by burning wood and to a lesser extent grass the original calcite component of the ash has been diagenetically altered to carbonated apatite around the cave periphery and to even more insoluble phosphate minerals in the centre one such mineral newberyite most likely formed by the reaction between guano degradation products and the ash under these circumstances bone preservation is also affected the overlying upper palaeolithic sediments contain calcite one of these layers abb contains much more calcite than all the other layers as well as abundant phytoliths derived from wood and grass this layer also contained many artifacts and bones it is thus concluded that ash is a major component of layer abb even though it is not visible to the maked eye in the form of hearths

aspects of the chemical and microscopic characteristics of plant ashes found in archaeological soils abstract ash from plants occurs in archaeological soils all over the world it is particularly significant in cave deposits but is also found on open air sites where dissolution has been discouraged by aridity deep burial or calcareous surrounding sediments this paper describes the main microscopic characteristics of ash as well as providing details and illustrations of their origin from plant mineral and organomineral compounds chemical summaries are presented which reflect the major trends in phytomineralogy and highlight some additional groupings running through plant physiology emphasis is placed on the importance of understanding the complete range of transformations acting on ash as a result of heating and cooling followed by weathering and dissolution finally some future directions for ash research are suggested both from within the central topic of plant ashes and extending to other types of ash

mineral assemblages in theopetra greece a framework for understanding diagenesis in a prehistoric cave abstract prehistoric cave sediments are often subjected to severe mechanical and chemical alteration making it difficult to interpret aspects of their archaeology theopetra cave offers unique opportunities to resolve aspects of this problem particularly in relation to chemical changes because it has a relatively well defined stratigraphy and its older deposits have been subjected to unusually severe diagenesis a study of the mineralogy and micromorphology of the sediments and in particular the phosphatic minerals that formed in the sediments after deposition shows that each stratigraphic unit has its own pattern of authigenic mineral distribution in some units these patterns vary sequentially in both lateral and vertical directions these variations reflect changing degrees of diagenesis and the observed patterns imply that every unit obtained its diagenetic fingerprint fairly soon after burial the prominent ash layers in the older sediments were subjected to unusually severe diagenetic alteration such that most of the relatively stable siliceous components of ash decomposed into amorphous silica an intimate association between ash minerals and the k fe phosphate mineral leucophosphite was also observed the sequential changes in authigenic mineral assemblages in theopetra are basically similar to those observed in several caves in israel raising the possibility that common processes are involved and that information obtained from these detailed studies can be applied to other caves in diverse geographic regions

differential burning recrystallization and fragmentation of archaeological bone abstract this paper presents research on the conditions under which progressive levels of burning may occur to archaeological bone and how burning damage changes bones crystal structure and susceptibility to fragmentation a k a friability experiments were conducted to simulate common patterns of high temperature bone diagenesis and fragmentation previously documented in paleolithic shelter sites bones buried up to 6 cm below the coal beds of the experimental fires were carbonized but calcination occurred only with direct exposure to live coals analysis by infra red spectroscopy reveals that marked changes in crystallinity accompany the macroscopic transformations in colour and friability of modern fire altered bone specifically a monotonic non linear decrease in mean fragment length across six colour categories was observed when samples were agitated or trampled and a concordant decline in bone identifiability first with respect to skeletal element and ultimately the recognizability of bone tissue itself these findings help qualify the behavioural and taphonomic implications of fragmented burned bones in archaeological sites especially with regard to potential stratigraphic associations between artefacts and hearth features in sites and the intensity of space use by human occupants the identification of burning damage on archaeological bone is a separate issue however it was found that the molecular signatures of recrystallization in modern burned bones partly overlap with recrystallization caused by weathering after only 1 to 2 years of exposure in an arid setting and by partial fossilization of archaeological bones over the long term while infra red and x ray diffraction techniques effectively describe heat induced changes in modern bone mineral and are an important aid for modelling diagenetic processes these techniques did not reliably identify burning damage to archaeological bones cross referencing readily visible colour phases with hcl insoluble fraction data proves much more effective and economically feasible for the latter purpose

the formation of fire residues associated with hunter gatherers in humid tropical environments a geo ethnoarchaeological perspective this work was supported by the people programme marie curie actions of the european union s seventh framework programme fp7 2007 2013 under rea agreement n 623293 granted to d e f at the mcdonald institute for archaeological research university of cambridge radiocarbon dating was also funded by the exilarch s foundation for the dangoor research accelerator mass spectrometry laboratory d reams

shell gathering from mangroves and the seasonality of the southeast asian monsoon using high resolution stable isotopic analysis of the tropical estuarine bivalve geloina erosa from the great cave of niah sarawak methods and reconnaissance of molluscs of early holocene and modern times this paper describes a reconnaissance high resolution study of stable isotopes 18o and 13c from modern shells of the estuarine bivalve geloina erosa and those dated to the early holocene that were harvested by people from mangroves near the great cave of niah on the north coast of borneo this reconnaissance study provides high resolution palaeoclimatic palaeohydrological information concerning early human activity in the region and the past character of the southeast asian monsoon laser ablation continuous flow isotope ratio mass spectrometry la cf irms on modern shells of geloina erosa revealed saw tooth stable isotopic profiles that bear a close resemblance to peaks and troughs of trends in recent local rainfall including the 1998 el nino drought highlighting the potential of geloina erosa for reconstructing seasonality of the southeast asian palaeomonsoon la cf irms analysis of prehistoric shells of geloina erosa held in the harrisson archives of the sarawak museum revealed cyclical shifts in 18o with similar amplitudes of variation as found in modern shells of geloina erosa as at the present day this probably reflects the changing seasonality of the monsoon rains with shifts to negative 18o values during periods of high runoff lighter mean 18o values of the prehistoric shells however may indicate a greater annual surplus of rainfall and possibly consistent with the early holocene strengthening of the summer monsoon at that time the similarity of the last growth increment 18o of the prehistoric shells to their mean 18o profile values suggests that gathering took place during times of moderate runoff

examining histology to identify burned bone abstract early research suggests that examination of the microscopic internal structure is a valid method for distinguishing burned from unburned bone in the archaeological record this study compares burned and unburned modern bones with archaeological bones from sibudu cave ca 60 000 years ago and cave of hearths over 200 000 years ago to more fully describe the heat induced histological changes to bone we also explore the effects of diagenesis on those changes to determine if histological evidence of burning preserves through fossilisation and diagenetic processes and can be successfully used to identify ancient burning application of this technique can help in addressing various issues including the origins of controlled use of fire and understanding animal butchery and disposal

post depositional alteration of humid tropical cave sediments micromorphological research in the great cave of niah sarawak borneo the post depositional alteration of cave sediments is of critical importance for the recognition identification and investigation of geoarchaeological and palaeoenvironmental evidence there have been relatively few studies of tropical cave sediments using micromorphology and this work represents one of the most detailed with 26 samples taken from deposits in the west mouth of the great cave of niah that cover the last 55 000 bp and contain the earliest known evidence for the remains of modern humans in southeast asia cave sediments situated in the humid tropics are subject to relatively high temperatures and moisture conditions that promote high rates of chemical alteration and geomorphic change this paper outlines those post depositional features that occurred in situ in the west mouth and include translocation and concentration bioturbation excrement bone alteration plant alteration clast alteration and guano decomposition it examines their implications for recognising past human activities e g fire altered materials the preservation of archaeological remains the nature of palaeoenvironments and of localised physical and bio geochemical processes

age and temperature constraints on metamorphism and exhumation of the syn orogenic metamorphic complexes of northern apennines italy abstract the apennine range is a young convergent orogen that formed over a retreating subduction zone syn orogenic metamorphic rocks are exposed in the mid tuscan ridge tuscan coast and tuscan archipelago and provide information about processes of continental subduction and exhumation associated with accretion and retreat apatite and zircon fission track analyses were applied to some of these syn orogenic metamorphic rocks the new low temperature thermochronological data helped to constrain the timing of the metamorphic peak and the age and modality of exhumation of these rocks that were structurally buried at 20 to 40 km depth during the main tectonogenic phase of the northern appenine belt in the giglio and elba islands and in the monti dell uccellina along the coast minimum ages of partially reset zircon samples yielded a first time constraint on the late oligocene age of the metamorphic peak the ca 27 ma obtained at the monti dell uccellina is coeval to that found in the alpi apuane located at the northern termination of the mid tuscan ridge the data from the tuscan archipelago point to a slightly older age in the monti pisani south of the alpi apuane and in the argentario promontary along the coast south of the monti dell uccellina completely reset zircon samples but composed by different populations were behaving as multiple thermochronometers and confirm the already proposed isothermal nature of the exhumation occurred after the metamorphic peak zircon p1 peak indicated that at 13 10 ma rocks were already at shallow crustal levels

extension uplift of rocks and cooling ages in thinned crustal provinces the larderello geothermal area inner northern apennines italy in extensional tectonic settings vertical movements of the earth s surface are largely controlled by rates of strain extensional strain rates within the larderello geothermal area located in inner parts of the northern apennines have been evaluated together with uplift rates and 40 ar 39 ar cooling ages results indicate that extensional strain rates have been relatively low 5 8 10 17 s 1 since the middle pliocene differential uplift rates are estimated to have been high c 0 2 mm year strain and uplift rates within the larderello region are consistent with the regional tectonic framework the low strain rate rapid uplifting and high heat flow within southern tuscany can be explained by an eastward dipping lithospheric shear maintained since at least middle pliocene times

geoarchaeological research in the humid tropics a global perspective abstract geoarchaeological research is now commonly undertaken as an integral component of archaeological investigations across much of the world however in humid tropical regions there is a relative shortfall of this earth science approach to understanding archaeological records in these regions where hot and humid conditions prevail for significant parts of the year sedimentological records are prone to high levels of diagenesis bioturbation and weathering this means that understanding and quantifying archaeological site formation processes can be very challenging because we may not have sufficient existing data with which to decipher the stratigraphic and microstratigraphic features recorded in these sequences in this paper we introduce a special issue of journal of archaeological science in which we showcase a selection of geoarchaeological research from across the equatorial regions of five continents highlighting the types of stratigraphic sequences and sedimentological features that are likely to be encountered and evaluating the tools that can be employed to maximise the geoarchaeological potential of these unique records additionally we use this opportunity to review geoarchaeology in the humid tropics from a global perspective outlining the main problems that geoarchaeologists face working in these environments and the techniques available with which to mitigate them

bone preservation in kebara cave israel using on site fourier transform infrared spectrometry abstract the distribution of bones in kebara cave israel is very heterogeneous in order to address the question of whether the bone concentrations were created secondarily by differential dissolution or represent the original burial distributions a portable fourier transform infrared spectrometer ftir was operated on site it was used to map the distribution of the minerals in the sediments in order to delineate the zone in which original ash derived calcite was preserved as well as the zone in which carbonate apatite dahllite was still preserved the bone distribution in the former zone must be primary as calcite is less stable than dahllite the mineral phase of bone the boundary between the zone containing dahllite in the sediments and the zone in which it was absent also essentially mapped the southernmost distribution of bones in the cave the distribution of bones in the dahllite zone is thus also likely to be original supporting this notion was the observation that the bones at the periphery of the concentrations were not less well preserved than those in the centre except at one location which coincided with the boundary of the dahllite zone in the third zone the bones appear to have been lost by dissolution the operation of an ftir on site proved to be an efficient and useful method for resolving this important archaeological problem

tertiary extensional tectonics in tuscany northern apennines italy abstract two extensional events have been recognized in the tertiary evolution of tuscany the first event occurred in the period between the late oligocene and late tortonian and caused a stretching of 120 or greater the second event occurred between the late tortonian and quaternary periods and caused a stretching not greater than 10 the first event is characterized by the exhumation of middle crust rocks and therefore by the development of core complexes the most significant structures of the first event are low angle normal faults which characterize the upper plate of the core complexes and ductile shear zones which characterize the lower plate the low angle normal faults tend to die out in the late triassic evaporite level which constitutes the main detachment of the core complexes the main structures of the second extensional event are high angle normal faults which dissect all the previous tectonic features these faults border tectonic depressions which were the site of clastic sedimentation from late tortonian to quaternary time these normal faults may tend to flatten in a seismic lozenge shaped band explained as an active extensional shear zone which is located at the brittle ductile boundary a similar explanation is given for the detachment located in the late triassic evaporite level during the first extensional event while the first extensional event is in the framework of the northern apennine post collisional evolution the second extensional event because it affects an already stretched crust could be attributed to the southern tyrrhenian opening which began during late tortonian

isotopic dating in metamorphic belts isotopic dating in metamorphic rocks is concerned with the timing of processes whose operation is controlled by continually changing physical conditions of these temperature has a pervasive influence and the use of physical models to elucidate the ways in which temperature is likely to vary is briefly reviewed the central concept of closure temperature is critically discussed and quantitative estimates for biotite and hornblende are evaluated in order to illustrate the factors which control closure temperatures and limit their application in practice the possibility of dating crystallization using minerals which crystallize below their respective closure temperatures is examined taking examples involving k ar rb sr sm nd and u pb analyses the indirect dating of metamorphism via structurally dated plutons is briefly considered and the problems of interpreting both discordant u pb zircon ages and rb sr whole rock isochrons in metamorphosed granites are discussed the value of near concordant zircon ages is emphasized the extent of isotopic equilibration during metamorphism specifically of sr isotopes in metasediments is shown not to be a simple function of metamorphic grade the flow of fluids produced by metamorphic reactions appears to be crucial and there is a potential for dating metamorphism using whole rock samples where such flow can he demonstrated independently the concluding discussion briefly examines existing data for the dalradian and indicates the potential for further progress using both well established and novel approaches

sedimentation re sedimentation and chronologies in archaeologically important caves problems and prospects excavations in the photic zones of caves have provided cornerstone archaeological sequences in many parts of the world before the appearance of modern dating techniques cave deposits provided clear evidence for the antiquity relative ages and co occurrence of ancient human remains material culture and fauna earlier generations of archaeologists had generally rather limited understanding of taphonomic and depositional processes but the twentieth century saw considerable improvement in excavation and analytical techniques the advent of modern dating and chronological methodologies offers very powerful tools for the analysis of cave fill deposits and this has resulted in the recognition of chronological incoherence in parts of some sites with consequent re evaluation of previous archaeological disputes obtaining multiple dates per context provides a means to assess the integrity and coherence of the archaeological and environmental records from cave fills in the case of the haua fteah libya this technique allowed the recognition of chronological coherence in low energy depositional environments and limited recycling in high energy contexts we provide a conceptual model of the relationship between recycling sedimentation rate and process energy high resolution investigation enables recognition of the complexity of the formation of cave sequences thus an increasingly sophisticated understanding of human behaviour and environmental relationships in the past and potentially gives a new life to old data

structure and late cenozoic evolution of the upper lithosphere in southwest tuscany italy abstract geological and geophysical data on southwest tuscany are reviewed in order to define the structure and evolution of the upper lithosphere from the miocene to the quaternary petrologic studies reveal the existence below all of tuscany of hercynian and older polyphased metamorphic rocks and of hercynian granite whose top is an important seismic reflecting horizon the basement is characterized by ne sw trending structures in contrast with the main nw se alpine structures of the uppermost levels the heat flow map shows two broad areas with values higher than 80 mw m2 reaching maximum values of 10 5 and 15 h f u in the geothermal areas which are also characterized by negative bouguer anomalies a landsat study revealed a ne sw band of subcircular structures passing through larderello and coinciding with a regional fault system and a steep rise in the moho petrologic geochemical and radiometric data on the tuscan igneous rocks show that partial melting took place in the tuscan crust at different levels and to varying degrees from the miocene to quaternary producing a continuous alpine granitic layer the known tuscan intrusive bodies and two batholiths below the larderello and mt amiata geothermal fields represent culminations of the alpine granite the rise of the tuscan magmas was closely correlated to a post tortonian tensional tectonics and followed its n e migration tensional tectonics started after the last compressional phase 10 11 ma b p as a consequence of the anticlockwise rotation of italy the opening of the tyrrhenian sea and the swelling of the mantle below southwest tuscany

modern humans in sarawak malaysian borneo during oxygen isotope stage 3 palaeoenvironmental evidence from the great cave of niah abstract during recent reinvestigations in the great cave of niah in borneo the hell trench sedimentary sequence seen by earlier excavators was re exposed early excavations here yielded the earliest anatomically modern human remains in island southeast asia calibrated radiocarbon dates pollen algal microfossils palynofacies granulometry and geochemistry of the hell trench sequence provide information about environmental and vegetational changes elements of geomorphic history and information about human activity the hell sediments were laid down episodically in an ephemeral stream or pool the pollen suggests cyclically changing vegetation with forest habitats alternating with more open environments indicating that phases with both temperatures and precipitation reduced compared with the present these events can be correlated with global climate change sequences to produce a provisional dating framework during some forest phases high counts of justicia a plant which today colonises recently burnt forest areas point to fire in the landscape this may be evidence for biomass burning by humans presumably to maintain forest edge habitats there is evidence from palynofacies for fire on the cave floor in the hell area since the area sampled is beyond the limit of plant growth this is evidence for human activity the first such evidence is during an episode with significant grassland indicators suggesting that people may have reached the site during a climatic phase characterised by relatively open habitats 50 ka thereafter people were able to maintain a relatively consistent presence at niah the human use of the hell area seems to have intensified through time probably because changes in the local hydrological regime made the area dryer and more suitable for human use

passive margins and their subsidence three main types of subsidence dominate the vertical tectonics of rifted inter plume passive margins these are the isostatic response to 1 stretching and thinning of the crust and lithosphere syn rift stage 2 cooling and thickening of the lithosphere mainly post rift stage and 3 sediment loading both stages additionally vertical movements occur at plume hot spot margins as a result of the anomalously hot underlying upper mantle and emplacement and cooling of magma three examples demonstrate various features of subsidence at inter plume passive margins at the north biscay starved margin the subsidence history can be mainly explained by syn rift lithospheric stretching followed by post rift thermal subsidence at the us atlantic margin the much greater overall subsidence results from the additional effect of sediment loading the tucano gabon graben system bordering the south atlantic is an example of strongly asymmetrical extensional tectonics during the syn rift stage which produced deep rifted basins within the adjacent continental borderland

the structure of the monte amiata volcano geothermal area northern apennines italy neogene quaternary compression versus extension the tectonic evolution of the mt amiata volcano geothermal area is under discussion some authors state that this region as well as the hinterland of the northern apennines were affected by compression from the cretaceous to the quaternary in contrast most authors believe that extension drove the tectonic evolution of the northern apennines from the early miocene to the quaternary field data seismic analyses and borehole logs have been integrated in order to better define the structural features of the continental crust in the mt amiata geothermal area in this paper i propose the hypothesis that the structure of the crust in the mt amiata volcano geothermal area derives from two main geological processes 1 contractional tectonics related to the stacking of the northern apennines cretaceous early miocene 2 subsequent extensional collapse of the hinterland of the mountain chain and related opening of the northern tyrrhenian sea early miocene quaternary compressional and extensional structures characterise the mt amiata region although extensional structures dominate its geological framework in particular the extension produced a middle late miocene boudinage of the previously stacked tectonic units b pliocene quaternary normal faulting which favoured the emplacement of a magmatic body in the middle upper crust and c the eruption of the mt amiata volcano which gave rise to an acid and intermediate volcanic complex 0 3 0 19 ma the extension produced the space necessary to accommodate the middle late miocene marine and continental sediments pliocene and quaternary normal and transtensional faults dissected the previous structures and influenced the early middle pliocene marine sedimentation within the structural depressions neighbouring the mt amiata volcano the magmatic body was emplaced at depth about 6 7 km during the pliocene extension and produced the eruption of the mt amiata volcano during the late pleistocene this gave rise to local uplift presently reaching about 3 000 m as well as a negative bouguer anomaly 16 mgal both centred on the mt amiata area the crustal dome shows a good correspondence with the convex shape of the regional seismic marker known as the k horizon which corresponds to the 450 c isotherm and the areas with greatest heat flow this is probably a consequence of the above cited magmatic body presently in the process of solidification a late pleistocene eruption occurred along a crustal fissure striking n50 mt amiata fault which crosscuts the crustal dome hydrothermal circulation proven by the occurrence of thermal springs and gas vents mainly co2 and h2s mainly occurs along the mt amiata fault both in the northeastern ans southwestern sides of the volcano

the role of extensional tectonics at different crustal levels on granite ascent and emplacement an example from tuscany italy abstract the role of regional extension on the rise and emplacement of granites in the crust is still debated pluton ascent and emplacement widely occurred in tuscany italy since late miocene during the post orogenic collapse of the inner apennines and are presently occurring in the geothermal areas of amiata and larderello tuscany offers a preferred test site to study the role of regional extension on pluton ascent and emplacement at different crustal levels ductile extension enhanced the segregation and ascent of granitic melts in the lower crust controlling pluton emplacement in correspondence with the brittle ductile transition in the brittle crust magma ascent occurred through subvertical faults and fractures compatible with the regional extension direction pluton emplacement mainly occurred by means of roof lifting the case of tuscany suggests that the extensional structures enhance melt segregation and ascent in the ductile crust but are not efficient alone to provide a pathway for the ascent of granitic magmas in the brittle extending crust the estimated magmatic strain rates due to pluton emplacement in the geothermal areas are much larger than the regional tectonic strain rates this suggests that regional tectonics did not control magma emplacement in the brittle crust and explains why nontectonic processes roof lifting accommodated the space required for pluton emplacement

local scale proxy evidence for the presence of closed canopy forest in north western borneo in the late pleistocene bones of strategy i bats from the archaeological record of the great cave of niah sarawak abstract the limits of the distribution of closed canopy forest in southeast asia during the glacial cycles of the pleistocene are the subject of continuing debate in this context this paper reports the results of an analysis of a novel line of evidence as a local scale case study 22 dated assemblages of bat bones that were recovered from the archaeological sequences of the great cave of niah in sarawak malaysian borneo were examined by examination of the morphological characteristics of the distal articulation of the humerus seven families and nine genera were identified five species level attributions could be made these assemblages formed a time series of 14 chronological intervals 48 0 35 ky bp ky bp 103 calibrated years before present 1950 incorporating samples from the high glacial interval 26 18 ky bp and last glacial maximum 23 19 ky bp bones of bat taxa that are adapted to forage in the cluttered environments in the interior of closed canopy forest strategy i bats were employed as proxy evidence for the presence of closed canopy forested habitats in the vicinity bones of strategy i bats principally small hipposideros spp were identified in all examined assemblages and intervals in the time series statistical testing indicated no evidence of differences in the absolute frequency of distal humeri from strategy i bats in the pleistocene samples 48 11 8 ky bp or in the entire time series 48 0 35 ky bp and no significant linear trend was found in the time series to suggest an increase of the bones strategy i bat taxa with the onset of the holocene these findings suggest that closed canopy forest habitats have been a persistent component in the landscape around the great cave of niah since 48 ky bp a taphonomic hypothesis is proposed to explain the dichotomy between the findings of this study and the pollen record of the site

bat guano and preservation of archaeological remains in cave sites the formation of authigenic minerals in cave sediments can be used to reconstruct the paleochemical conditions that prevailed in the past and in this way to assess the completeness of the archaeological record previous studies indicated that the major driving mechanisms for chemical diagenesis in prehistoric caves that result in the formation of authigenic minerals are the degradation of bat guano and the local hydrology we therefore investigated contemporary bat guano deposits in caves and the sediments directly below such deposits the emerging patterns show that the formation of authigenic minerals occurs under acidic conditions within tens of years the availability of phosphate al k and fe increases with increasing organic matter degradation while the availability of nitrogen and sulfur decreases insectivorous bat guano contains larger amounts of phosphate and is more acidic than fruit bat guano in the first stages of diagenesis micro chemical environments form within the degrading bat guano that result in the formation of a wide variety of authigenic minerals during advanced stages of diagenesis steady state conditions are achieved resulting in authigenic mineral assemblages being dominated by one mineral type at the same locale this is reminiscent of known distributions of authigenic minerals in prehistoric cave sediments under the acidic conditions produced by degrading bat guano deposits calcareous artifacts and bones are not expected to persist for long periods of time unless there is a lot of calcite in the sediments that could buffer the sediment water ph guano itself is not likely to be preserved periods of cave abandonment can be inferred from the presence of authigenic minerals in the sediments as it is during these times that bats mainly occupy the cave the occurrence of certain authigenic minerals in open air sites may serve as evidence for areas rich in organic matter containing phosphate i e animal enclosures latrines sewers trash pits and or bones as the degradation process is rapid the use of authigenic minerals to identify these loci is relevant to almost all archaeological as well as historical sites

highly extended terrains lateral segmentation of the substratum and basin development the middle late miocene radicondoli basin inner northern apennines italy 1 this paper deals with the evolution of sedimentary basins not delimited by normal faults with a substratum characterized by an upward concave shape and with infilling sediments synclinally deformed we describe the middle late miocene radicondoli basin representing an example of such bowl shaped basins its tectonic origin is controversial being related both to compression and extension these opposite interpretations bear significant consequences on the geodynamic context in which the inner northern apennines developed during the middle late miocene the results of our structural studies carried out in the substratum and infilling sediments indicate that the radicondoli basin is an example of a hanging wall basin developed in an extensional setting extensional tectonics determined the lateral segmentation of the substratum competent levels i e tuscan nappe and verrucano group and the consequent collapse of overlying less competent levels i e the ligurian units with the formation of a bowl shaped tectonic depression here the syntectonic sediments serravallian late messinian are deformed in a large syncline characterized by minor gravity driven folds with vergences toward the depocenter and traces of their axial planes parallel to the basin margins this paper highlights the role of the competence contrast during the postcollisional tectonic evolution and the influence of substratum lateral segmentation for the accommodation of syntectonic sediments

petrifaction of wood by silica minerals abstract seventy five woods of australian origin have been examined by means of x ray diffraction optical and scanning electron microscopy and differential thermal analysis the silica is in one or other of the following forms opal a opal ct chalcedony quartz quartz chalcedony opal chalcedony more than half of them consist of opal ct or chalcedony the results indicate that petrifaction by silica involves penetration of the wood via splits or checks permeation of cell walls via a reticulated system of micropores enlargement of the micropore system as cell wall components break down and continuing deposition of silica ata rate and in a manner consistent with maintaining the dimensional stability of the wood deposition of silica in cell lumina and intercellular voids may be sometimes but not always a separate and later event the final stages of lithification involve loss of water and perhaps transformation of one form of silica into another

uniform sense normal simple shear of the continental lithosphere geophysical studies suggest that the thin crust characteristic of the basin and range province extends eastward beneath the west margin of the colorado plateau and rocky mountain regions in arizona and utah zones perhaps over 100 km wide may be defined bounded on the west by the east limit of upper crustal normal faults that account for more that 10 extension and on the east by the east limit of thinning beneath the colorado plateau a discrepancy exists within these zones between the negligible extension measurable in the upper crust and the substantial extension apparent from crustal thinning assuming the discrepant zone crust was as thick as or thicker than the colorado plateau rocky mountain crust prior to extensional tectonism if various theories appealing to crustal erosion are dismissed mass balance problems evident in the discrepant zones are most easily resolved by down to the east normal simple shear of the crust moving lower and middle crustal rocks that initially were within the zones up and to the west to where they now are locally exposed in the basin and range province west of the discrepant zones in both arizona and utah east directed extensional allochthons with large displacement are exposed these geophysical and geological observations complement one another if it is accepted that the entire crust in both arizona and utah failed during extension on gently east dipping east directed low angle normal faults and shear zones over a region several hundred kilometres wide large scale uniform sense normal simple shear of the crust suggests the entire lithosphere may do the same such a hypothesis predicts major lithospheric thinning without crustal thinning will occur in plateau areas in the direction of crustal shear in the case of the arizona utah and red sea extensional systems and possibly the death valley extensional terrain a broad topographic arch typically 1500 2000 m higher than the extended terrain is present suggesting lithospheric thinning in areas predicted by the hypothesis

extensional shear zones as imaged by reflection seismic lines the larderello geothermal field central italy the larderello geothermal field is located in the inner northern apennines in an area which has been subject to extension since the early miocene the latest extensional episode pliocene present has resulted in the formation of nw trending nedipping listric normal faults whose geometry is controlled down to f3 km by borehole data in this paper we integrate a new interpretation of seismic reflection lines with existing seismic field and borehole data to analyse the relations among listric normal faults the top of the brittle ductile transition and the migration of geothermal fluids in accordance with previous interpretations we consider the strong reflector k horizon marking the top of the reflective mid lower crust and located at a depth of 3 5 km in the geothermal area to represent the top of the brittle ductile transition its reflectivity most probably derives from the presence of overpressured fluids we identify three main nw trending nedipping extensional brittle shear zones showing listric geometry and soling out in the vicinity of the k horizon the latter appears to be dislocated in correspondence of the soling out of the shear zones these shear zones because of the associated intense fracturing represent the most natural channels of upward migration of geothermal fluids from the magmatic sources located below the k horizon we suggest that these two conclusions that listric normal faults root at or near the brittle ductile transition and that they act as preferential upward migration paths for magmatic fluids may be of general validity for geothermal fields located in extensional settings d 2002 elsevier science b v all rights reserved

surface uplift uplift of rocks and exhumation of rocks uplift of the surface of mountain belts requires forces that are comparable in magnitude to those associated with plate motion and therefore determination of rates of surface uplift could provide important information on the dynamics of mountain ranges rates of uplift of the surfaces of mountain ranges have not however been quantified sufficiently well that they provide useful constraints on those processes many reports off surface uplift in mountain ranges are based on mistaking exhumation of rocks or uplift of rocks for surface uplift and provide no information whatsoever on the rates of surface uplift

migration of geothermal fluids in extensional terrains the ore deposits of the boccheggiano montieri area southern tuscany italy an integrated study based on fluid inclusion 18o composition and structural analyses was carried out on a pliocene fossil hydrothermal system located to the south of the present active larderello geothermal field in the boccheggiano montieri area the study area is typified by mineralized cataclastic levels related to late oligocene early miocene thrust surfaces and to the following two generations of normal faults of miocene and pliocene ages respectively within the damage zone of the pliocene boccheggiano fault the mineralization is mainly made up of quartz and pyrite quartz pb zn sulfides or quartz pb zn sulfides fluorite carbonates assemblages occur instead in the older cataclastic levels two generations of liquid rich fluid inclusions were recognized in quartz and fluorite the first one with homogenization temperatures ranging between 172 and 331 c and salinity between 0 0 and 8 8 wt naclequiv records the early stage of hydrothermal activity the second generation of fluid inclusions documents a later stage with homogenization temperature from 124 to 288 c and salinity from 0 2 to 1 9 wt naclequiv fluid inclusions analyses also indicate that mixing of fluid with distinct salinities and or temperatures was a widespread process during the early stage and that fluid temperatures decreased moving from the boccheggiano fault toward the more distal and older cataclastic levels the 18o values of water in equilibrium with hydrothermal quartz which range from 5 7 to 0 1 are related to the circulation of meteoric water mixed with saline water that leached the evaporite level and enriched in 18o through water rock interaction and or with magmatically derived fluids results indicate that the damage zone of the pliocene boccheggiano fault represented the main channel for the flow of meteoric water which was heated at depth then mixed with high salinity fluids and finally ascend to infiltrate along the older cataclastic levels our results based on fluid inclusions oxygen isotopic compositions and structural analyses indicate that a single fluid flow path run through the damage zone of the boccheggiano fault and the older cataclasites which were thus hydraulically connected

low angle normal fault lanf zone architecture and permeability features in bedded carbonate from inner northern apennines rapolano terme central italy abstract fault zones have the capacity to be hydraulic conduits within upper crustal levels allowing migration of large volume of fluids through shallow and deeper geological environments low angle normal faults lanfs crosscutting carbonate rocks produce damaged volumes that may have a relevant role in channelling or hosting geothermal fluids therefore deserving of investigation to better predict mining targets deformation along lanfs zones dissecting carbonate successions produces permeable volumes presently exploited in the larderello and monte amiata geothermal areas italy in this paper the architectural and permeability features of an exhumed lanf zone exposed in the northern apennines rapolano terme central italy affecting cretaceous bedded limestone are presented such a fault was not affected by circulation of geothermal fluids but its features could reveal much on the potential impact on fluids migration in the active geothermal areas therefore resulting an intriguing analogue the study lanf zone consists of faults which enucleated at depth 4 km during its earlier stage of evolution dissolution seams often arranged in s c fabric characterised the whole damage zone dissolution seams developed under very low grade metamorphism t 100 150 c as indicated by illite crystallinty analyses fault zone architecture and permeability features changed during the fault growth and exhumation permeability heterogeneity and anisotropy characterised the lanf zone during its development if geofluids circulated within the fault zone it could be an effective barrier during its earlier evolution being accompanied by dissolution seams on the contrary it could play as combined barriers conduits during its later evolution progressively at shallower levels being characterised by intersecting fault planes which define pipe like conduits parallel to the direction of the tectonic transport such a configuration could have the capacity to impact on fluids migration for long paths across the upper crustal levels this adds significant information for predicting deeper geothermal circuits and the location of potential exploitable reservoirs in active tectonic environments

late evolution of the inner northern apennines from the structure of the monti del chianti monte cetona ridge tuscany italy abstract the neogene and quaternary tectonic evolution of the inner northern apennines i e southern tuscany and northern tyrrhenian sea as well as its crustal features i e low crustal thickness neogene quaternary magmatism widespread geothermal anomalies lateral segmentation of the stacked tectonic units extensive deep sedimentary basins are framed in different geodynamic scenarios compressional extensional or both pulsing consequently the basin and range structure that characterises the northern tyrrhenian sea and southern tuscany is considered as a consequence of i out of sequence thrusts and related thrust top basins ii polyphased normal faulting that formed horst and graben structures or iii a combination of both this paper provides a new dataset from a sector of the eastern inner northern apennines i e monti del chianti monte cetona ridge contributing to this scientific debate new fieldwork and structural analysis carried out in selected areas along the ridge allowed to define the chronology of the main tectonic events on the basis of their influence on the marine and continental sedimentation the dataset supports for early miocene serravallian in sequence and out of sequence thrusting thrusting produced complex staking patterns of tuscan and ligurian units extensional detachments developed since later middle miocene and controlled the neogene sedimentation in bowl shaped structural depressions later dissected by normal faults enhancing the accommodation space for pliocene marine deposits in broad nnw trending basins siena radicofani and valdichiana basins in this perspective no data supports for active continuous or pulsing compressional tectonics after late serravalian as a result in the whole inland inner northern apennines the extensional tectonics was continuously active at least since middle miocene and controlled the basins development magmatism and structure of the crust and lithosphere

exhumation of deep crustal metamorphic rocks and crustal extension in arc and back arc regions we adress the problem of exhumation of metamorphic rocks in arc and back arc positions based on observations of the aegean and tyrrhenian back arc regions in both regions back arc extension has been active for 25 ma at least while convergence and crustal thickening was going on at the thrust front compressional structures are reworked in the back arc domain as extensional flat lying detachments which allow unroofing of the metamorphic pile metamorphic rocks suffer first a dynamic burial during nappe stacking and then fast exhumation when they reach the extensional region we describe a continuous process of burial and exhumation that is contemporaneous with the migration of the thrust front toward external zones the front of extension follows behind at approximately one hundred kilometers at the convergence front continuous subduction of a cold oceanic slab or continuous accretion of continental units keeps a cool p t gradient and hp lt metamorphic rocks are formed at depth the overall cool environment leads to a deep brittle ductile transition and thus to a resistant crust which can sustain its large thickness while the thrust front propagates forward parts of the accretionary wedge which were formed earlier enter the back arc domain which can be already under extension and which is warmer because of a greater distance to the cold slab and the presence of the volcanic arc the brittle ductile transition rises in the thick crust which then becomes unstable and subsequently collapses the exhumation history of metamorphic rocks below detachments is two fold 1 a constantely thickening crust is unroofed by flat lying detachments which rework early thrusts this first period is characterized by a good preservation of hp lt parageneses 2 the second period is when rocks are in the zone of crustal scale extension of the back arc region deep crustal metamorphics are exhumed below flat lying detachements which affect the whole crust

rb sr and k ar ages on minerals at temperatures of 300 400 c from deep wells in the larderello geothermal field italy rb sr and k ar ages have been obtained on six biotites two muscovites and one hornblende from samples of micaschist gneiss and amphibolite of lower paleozoic to precambrian age at a depth exceeding 2 000 m in basement rocks of the larderello travale geothermal region most of the data cluster in the range 2 5 3 7 ma revealing the existence of a pliocene thermal event to which the origin of the field may be attributed the resulting duration of the larderello geothermal field is unexpectedly long in the basement levels of the two wells examined unstabilized minimum temperatures of 290 and 380 c were measured all the biotites show almost complete 40ar and 87sr retention at the measured well temperatures petrologic evidence stilpnomelane stability and experimental data activation energies and diffusion coefficients also favour a closure temperature above 400 c for rb sr and k ar in biotites in agreement with recent direct experimental determinations

initial micromorphological results from liang bua flores indonesia site formation processes and hominin activities at the type locality of homo floresiensis liang bua a karstic cave located on the island of flores in eastern indonesia is best known for yielding the holotype of the diminutive hominin homo floresiensis from late pleistocene sediments modern human remains have also been recovered from the holocene deposits and abundant archaeological and faunal remains occur throughout the sequence the cave the catchment in which it is located and the gross aggradational phases of the sediment sequence have all been subject to a great deal of scientific scrutiny since the discovery of the holotype of h floresiensis in 2003 a recent program of geoarchaeological research has extended analyses of the site s deposits to the microstratigraphic micromorphological level the stratigraphic sequence in the cave is well defined but complex comprising interstratified sediments of diverse lithologies and polygenetic origins including volcanic tephras fine grained colluvium coarse autogenic limestone gravels speleothems and anthropogenic sediments such as combustion features the sedimentological and chemical heterogeneity suggest that processes of site formation and diagenesis varied markedly through time both laterally and vertically we present initial results from samples collected in 2014 from an excavation area near the rear of the cave which yielded radiocarbon ages from charcoal that fill an important temporal gap in the chrono stratigraphic sequence of previously excavated areas of the site the results indicate marked changes in site environment and hominin activity during the late pleistocene relating primarily to the degree to which the cave was connected to the hydrogeological system and to the varying intensities of use of the cave by hominins importantly we identify anthropogenic signs of fire use at the site between 41 and 24 thousand years ago most likely related to the presence of modern humans

lamellae formation processes in tropical soils in southeastern brazil abstract the pedogenic genesis of lamellae is commonly reported as involving clay illuviation however some pedogenic lamellae in tropical soils may be formed by a different process involving the degradation of a continuous bt horizon and an intense loss of clay in the present work we investigated soils along a toposequence containing lamellae formed both by illuviation and bt degradation to better understand the pedogenic processes and the environmental controls associated with the genesis of lamellae in tropical soils soils were described and sampled along a hillslope in the sao pedro region sao paulo state and submitted to physical particle size chemical ph and exchangeable cations and micromorphological analyses in the upper segment of the studied hillslope dominated by low gradients the soil is deep reddish and contains a sequence of 12 to 20 lamellae interlamellae an examination of thin sections revealed abundant illuvial features formed by moderately to strongly oriented clay bridges between sandy particles in the lamellae supporting an illuvial origin in the middle segment of the hillslope characterized by higher gradients the soil is shallower and yellowish presents some mottles and contains a sequence of 2 lamellae interlamellae field descriptions showed curved links between these lamellae and the underlying bt as well as isolated spots similar to lamellae within interlamellae the lamellae bt curved links and spots present similar micromorphological characteristics and only a few illuvial features which suggest a genetic relationship between lamellae and the bt horizon and minimize the importance of clay illuviation the origin of these lamellae is related to the degradation of bt and clay eluviation by subsurface lateral flows developed mainly in the contact between bt and the overlying more permeable horizons this process seems to be an important way of lamellae formation under tropical climate and should thus be incorporated into the term pedogenic lamellae which is usually associated in the international literature with lamellae formed by clay illuviation

crustal extension in the northern apennines the transition from compression to extension in the alpi apuane core complex an interpretation of northern apennine geology is presented which relates the temporal and spatial occurrence of both compressional and extensional deformation features in terms of the changing dynamic evolution within an accretionary wedge after a model proposed by platt 1986 followed by the initiation and development of continental rifting during cretaceous to eocene time an accretionary wedge formed as remnant tethyan oceanic crust subducted beneath the rotating corsica sardinia microplate microplate collision during the oligocene was characterized by the rapid imbrication of buoyant continental crust of the italian continental margin the record of which is preserved within the duplex structure geometry of the alpi apuane region the overthickened wedge geometry returned to a more stable configuration by developing extensional features during the miocene both listric normal faults at upper crustal levels and shear zones indicating evidence of distributed ductile extensional strain at mid crustal levels are recorded it is proposed that large scale regional extension with associated volcanism beginning in the messinian was represented by the intrusion of asthenospheric material from the subducted plate into the already attenuated accretionary complex further rifting perhaps aided by subduction and back arc processes in the southern apennines led to the formation of the tyrrhenian sea as an oceanic basin both the apennines and north american core complexes record evidence of crustal thickening followed by crustal thinning and finally of continental rifting this suggests that the similar histories of these regions with vastly different plate tectonic settings may both be explained by processes linked to the changing internal dynamics of accretionary wedges

microscopic evidence of subglacial deformation abstract subglacial deformation is by now a well established process however recognition of this process in pleistocene tills is not always clear studies of thin sections of pleistocene tills show that there are a variety of microscopic features caused by deformation this paper gives a review of microscopic evidence for subglacial deformation and starts with a case where deformation could be established macroscopically then traces the microscopic features through planar and rotational movements which are described and separated accordingly attention is also given to features caused by crushing of grains and sediment dewatering these studies indicate that almost all basal tills show evidence of subglacial deformation rather than sedimentary derivation this implies that if we want to understand subglacial processes such tills should be described in tectonic rather than sedimentary terminology

the north tyrrhenian northern apennines post collisional system constraints for a geodynamic model the north tyrrhenian northern apennines post collisional system ntas has been analysed on the basis of marine reflection profiles and bibliographic sources with the aim of providing an up to date geotectonic and evolutive framework consistent with structural data the continental rifting began to affect the most internal western side of the system in the middle upper miocene while the most external eastern zones were touched by rifting only in pleistocene times the birth and development of extensive asymmetric basins took place with a progressive speeding up of rifting towards the external sectors a diachronous regionally extended and eastward rejuvenating unconformity recognizable within the neogene quaternary basins marks the passage from the syn rift to the post rift tectonic regime while the first is everywhere dominated by extension the second one produces vertical movements reflection terminations related to this unconformity are interpreted in terms of vertical tectonic component three zones that experienced different post rift vertical movements are thus recognized in the ntas subsidence in the north tyrrhenian deep water region tectonic stability or alternation of moderate subsidence and uplift in the continental shelf and western tuscany strong uplift in eastern tuscany the updated structural data demonstrate that the ntas upper crust is crosscut by both tyrrhenian dipping and apennine dipping low angle detachment planes above which the upper crustal blocks rotated and experienced extensional transport along two opposite directions to the west and to the east respectively the coexistence of opposite dipping crustal surfaces bears two fundamental implications for the ntas geodynamics first it stresses the importance of the anti apennine transfer faults since they separate crustal blocks of opposite extension polarity secondly it testifies that the extension tectonics not only re utilized former crustal thrust planes but also gave origin to new significant e and ne dipping detachment planes plan and crossview geometries of faults together with considerations on the role of the metamorphic core complexes point to an interpretation of the ntas structure that is more consistent with the anastomosing shear model rather than the simple shear or the delamination ones

evaluating the geogenic co2 flux from geothermal areas by analysing quaternary travertine masses new data from western central italy and review of previous co2 flux data abstract quantification of carbon fluxes between solid earth and its atmosphere is necessary to understand the global geological carbon cycle some of the main co2 contributors are metamorphism and magmatic mantle degassing co2 is discharged from active and quiescent volcanoes fault zones geothermal systems and co2 rich groundwater here a new method for the estimation of the geogenic flux of co2 from tectonically active regions based on the volume composition and age of travertine deposits is proposed the method is applied to the travertine deposits of western central italy where travertine deposition is driven by degassing of co2 charged groundwater results show that the study areas are characterized since middle pleistocene by diffuse co2 degassing processes with time averaged co2 fluxes ranging between 1 24 0 12 106 mol y 1 km 2 and 1 38 0 42 106 mol y 1 km 2 these values are of the same order of magnitude of carbon dioxide fluxes measured by different methods in western central italy and are higher than the global baseline co2 flux from high heat flow regions the review of the available 234u 230th and 14c data shows that the co2 degassing processes that affects western central italy nowadays were already active at least 350 ka ago proving that this region is a globally relevant case for the study of earth degassing considering the widespread occurrence of travertine deposits in tectonically active areas worldwide the proposed approach can be used as a reliable tool to estimate the co2 flux in different geodynamic settings within system earth

heat flow deep temperatures and extensional structures in the larderello geothermal field italy constraints on geothermal fluid flow the larderello geothermal field is located in the inner northern apennines southern tuscany an area which has been affected by extensional tectonics since the early middle miocene the structure of the larderello field is characterised by nw trending ne dipping pliocene to present normal faults their geometry down to depths of 4 5 km is constrained by field borehole and reflection seismic data an association between extensional structures and heat flow maxima up to 1000 mw m2 is recognisable from detailed surface heat flow mapping in order to investigate the relationships among extensional structures and heat flow subsurface isotherms were traced subject to borehole control along variously oriented geological cross sections the isotherms show vertical displacements associated with the recent normal faults and related deformation zones which reach the brittle ductile transition estimates of the relative importance of convective and conductive components of heat flow suggest that fluid circulation is particularly important in correspondence with the normal faults accounting for the correlation between isotherm perturbations and extensional structures in this view extensional shear zones are interpreted as the main structural pathways for the flow of hot geothermal fluids

the vegetation and climate at the last glaciation on the emerged continental shelf of the south china sea studies on the dispersal mechanism and source areas of pollen from hemipelagic sediments recovered from the continental slopes of the south china sea scs reveal that vegetation existed on the exposed shelves at the last glacial maximum lgm and the latter part of the marine isotope stage 3 at the low sea level stand artemisiadominated grassland covered the northern continental shelf and tropical lowland rainforest and mangroves grew on the southern shelf sunda land consequently the climate in the northern scs must have been much colder and drier during the last glacial period compared to the present sunda land experienced only a marginally lower temperature but was not drier than today the enhanced contrast between the northern and southern parts of the scs in vegetation and climate during the lgm may be ascribed at least partly to the strengthening of winter monsoon during the last glacial period 2000 elsevier science b v all rights reserved

kinematics and geometry of miocene low angle detachments and exhumation of the metamorphic units in the hinterland of the northern apennines italy abstract this paper deals with the lateral segmentation crustal boudinage and exhumation of the metamorphic units in the hinterland of the northern apennines during the late miocene extension the study area mt leoni area is part of the middle tuscan ridge a regional morpho tectonic feature in which the deepest tectonic units of the northern apennines are broadly exposed crustal seismic profiles and deep boreholes indicate that the middle tuscan ridge coincides with the outcropping part of a laterally discontinuous geological body mainly made up of hp lt and greenschist facies metamorphic units extensional detachments characterised by top to the east sense of shear and staircase geometry produced the lateral segmentation of the metamorphic units their activity can be ascribed to late tortonian late messinian times geometry and kinematics of the extensional detachments have been compared with the miocene extensional structures developed at shallow depths in the overthickened crust of the northern apennines allowing understanding of the extensional tectonic evolution which reorganised the hinterland northern apennines collisional belt