unraveling tectonic and climatic controls on synorogenic growth strata northern apennines italy we develop a new high resolution stratigraphic age model to unravel the contributions of tectonic and climatic processes on early to late pleistocene synorogenic growth strata we capitalize on excellent continuous exposures along the flank of the po foreland in northern italy to elucidate hydrologic geomorphic and sedimentologic processes that are regularly attributed to but rarely proven to be caused by glacial interglacial climatic changes and unsteady rock uplift we perform our analysis on the enza section a succession of marine and terrestrial strata exposed along the enza river between parma and reggio emilia northern italy bedding in the enza section displays synorogenic growth strata geometry with bedding dips that range from 2 to 55 that becomes progressively shallower upsection we develop an age model that incorporates biostratigraphy magnetostratigraphy rock magnetic cyclostratigraphy cosmogenic radionuclide burial dating and optically stimulated luminescence dating and shows that the enza section spans the interval between 0 04 and 1 65 ma furthermore the age model pins the time of deposition for several lithostratigraphic units of regional significance and shows that sediment accumulation was unsteady ranging from 14 31 cm k y in the marine part of the section to 5 362 cm k y in the overlying littoral and terrestrial part of the section unsteady deposition is most pronounced in the terrestrial deposits where thick fluvial gravel packages accumulated in short 10 15 k y time periods that coincide with quaternary glacial intervals there is direct evidence for a dominant tectonic control in the older marine part of the section here sediment accumulation rates on the limb of the fold growing along this portion of the northern apennine mountain front show that between 1 07 and 1 65 ma repetitive progradation of neritic sand units directly followed pulses of rapid punctuated uplift in contrast the cyclic terrestrial facies variations in the enza section reveal that once the section became emergent at ca 1 ma and uplift slowed climate was the dominant control on sediment production and deposition

active fault related folding in the epicentral area of the december 25 1222 io ix mcs brescia earthquake northern italy seismotectonic implications abstract a dense grid of petroleum industry seismic reflection profiles coupled with field mapping exploratory trenching and geomorphic and structural analysis are used to characterize the quaternary growth history of the capriano del colle fault system one of several inferred active buried thrusts that extend across the po plain in northern italy shortening is characterized here by a deeply buried south vergent forethrust and an associated north vergent backthrust whose upward propagation is expressed by fault propagation folding near the surface structural interpretation based on seismic data suggests that strain is accommodated at very shallow levels by secondary flexural slip thrusts and reverse faults developed on synclinal flanks that emanate from active axial surfaces analysis of syntectonic growth strata document maximum rates of dip slip of 3 45 0 66 mm yr 1 6 myr 1 2 myr and 0 47 0 22 mm yr during a more recent time period 0 89 myr present a quarry excavation at capriano del colle allows a preliminary paleoseismologic analysis of coseismic surface faulting and liquefaction exposed near the core of an active mid pleistocene to holocene anticline these features are interpreted to be generated during strong local earthquakes consistent with the environmental effects and ground motions of an event similar to the december 25 1222 brescia earthquake io ix mcs this indicates for the first time that compressive folds and blind thrusts in the po plain are currently accommodating slow rates of modern contraction in an active zone of the southern alps that extends from lake garda to varese we thus argue that earthquakes similar to the december 25 1222 brescia event are likely to occur in this region and pose a direct threat to such a densely populated and developed area

burial of organic carbon and pyrite sulfur in sediments over phanerozoic time a new theory in present day marine sediments almost all of which are deposited in normal oxygenated seawater rates of burial of organic carbon c and pyrite sulfur s correlate positively and bear a constant ratio to one another c s 3 on a weight basis by contrast calculations based on the isotopic model of garrels and lerman 1981 indicate that at various times during the phanerozoic the worldwide burial ratio must have been considerably different than the present day value this ratio change is caused by the requirement that increases in the worldwide mass of organic carbon must be accompanied by equivalent decreases in the mass of sedimentary pyrite sulfur in order to maintain a roughly constant level of o2 in the atmosphere such apparently contradictory behavior can be explained if the locus of major organic carbon burial has shifted over time from normal marine environments as at present to non marine freshwater or to euxinic environments in the geologic past a shift to predominantly freshwater burial can help explain predicted high c s ratios in permo carboniferous sediments and a shift to euxinic environments can help explain predicted low c s ratios during the early paleozoic it is demonstrated that the three environments today exhibit distinguishably different average c s ratios

paleosols and associated channel belt sand bodies from a continuously subsiding late quaternary system po basin italy new insights into continental sequence stratigraphy previous sequence stratigraphic work has emphasized the key role of paleosols and associated sand dominated fluvial bodies as key features for interpreting alluvial architecture the temporal resolution of the ancient record is however insufficient to fully explain the complex relationship between soil formation and the evolution of fluvial systems under changing sea level and climate conditions in this paper we present a detailed record of paleosol channel belt relationships reconstructed from the subsurface of a rapidly subsiding region po plain italy that spans almost all of the last glacial interglacial cycle 120 k y the studied succession preserves a systematic bipartite zonation into a thick paleosol bearing segment close to the basin margin and a sand dominated interval with vertically amalgamated channel belts in an axial position individual paleosols are weakly developed and represent key stratigraphic markers that can be traced basinwide into adjacent essentially contemporaneous unconfined channel belt deposits unlike conventional models of late quaternary alluvial coastal plain systems no persistent incised valley was established in the po system during the last glacial interglacial cycle continuous accommodation was the key depositional control on alluvial stratigraphy during the prolonged 90 k y phase of late pleistocene sea level fall which led to the deposition of a thick dominantly aggradational alluvial succession the development of shallowly incised short lived valley systems took place only at the transition to glacial stages associated with substantial sea level drop marine oxygen isotope stage mis 3 2 transition and possibly mis 5 4 transition this study shows that in rapidly subsiding settings with high rates of sedimentation incised valley systems may be replaced by aggradationally stacked essentially nonincised fluvial bodies in these cases overbank packages bounded by immature paleosols represent the most likely alternative to the highly weathered interfluve paleosol predicted by classic sequence stratigraphic models fourth order sequence boundaries and lower rank erosional surfaces may be easily confused at the 100 k y scale and transgressive surfaces defining the onset of retrogradation may become the most readily identifiable sequence stratigraphic surfaces

a sequence of partial melting reactions at mt stafford central australia metasedimentary gneisses show a rapid change in grade in a 10 km wide low p high t regional aureole at mt stafford in the arunta block central australia migmatite occurs in all but the lowermost of five metamorphic zones which grade from greenschist zone 1 through amphibolite zones 2 3 to granulite facies zones 4 5 the sequence of partial melting reactions inferred for metapelitic rocks is dependant upon protolith temperature and fluid conditions the metapelite solidus in zone 2 reflects vapour present melting at p 3 kbar and t 640 c melting having initially been controlled by the congruent breakdown of the assemblage crd kfs bt qtz at slightly higher temperature andalusite in leucosome formed via the reaction kfs qtz bt h2oand melt and melt having been stabilized by the presence of boron sillimanite coaxially replaces andalusite in the high grade portion of zone 2 in zone 3 large aluminosilicate aggregates in leucosome are armoured by spl crd grt symplectites garnet partially pseudomorphs biotite cordierite or spinel in high grade portions of zone 3 zone 4 grt crd opx bearing metapsammite assemblages and garnet bearing leucosome reflect t 800 c and p 2 2 0 9 kbar in the model kfmash system the principal vapour absent melting step reflected significant modal changes related to the breakdown of the as bt tie line and the establishment of the spl crd tie line the bulk rock geochemistry of migmatite samples straddle the spl crd tie line the aluminous bulk rock composition of the common bedded migmatite restricted its potential to witness garnet forming and orthopyroxene forming reactions minor textural and modal changes in and above zone 3 reflecting biotite destablization in biotite poor assemblages

ocean chemistry during glacial time abstract measurements of co2 to air ratios in the gas trapped in bubbles in ice of glacial age suggest that the co2 content of the atmosphere was considerably lower during peak glacial time than during holocene time the purpose of this paper is to show that such a change must in all likelihood be the result of alterations in the nutrient element chemistry of sea water two possible scenarios are presented one involves alternate storage and erosion of phosphorous leaving residues from shelf sediments the other involves changes in the c p ratio in the organic debris falling to the deep sea means of verifying the nutrient cycle hypothesis are also given it is shown that the 13c record as we know it in planktonic and benthic foraminifera the oxygen record as inferred from benthic foraminifera species distributions and the early post glacial caco3 preservation event as recorded by aragonitic pteropods are consistent with both of the hypotheses presented only if an early post glacial spike in the 13c record for planktonic shells could be found would it be possible to eliminate one of these hypotheses i e that involving shelf storage the implications of these nutrient hypotheses to climate theory are as follows if shelf storage is responsible for the glacial to interglacial co2 increase then the co2 change must be considered an amplifier of some primary cause the reason is that sea level changes are needed to drive deposition on and erosion from the shelves on the other hand if changes in the c p ratio for falling debris are responsible then the co2 change could either be an amplifier or a primary cause for the major glacial to interglacial climatic cycle the latter is possible as self sustained oscillations in ocean chemistry might be driven by interactions between ocean ecology and ocean nutrient chemistry

late cenozoic uplift of mountain ranges and global climate change chicken or egg the high altitudes of most mountain ranges have commonly been ascribed to late cenozoic uplift without reference to when crustal thickening and other tectonic processes occurred deep incision and recent denudation of these mountain ranges abundant late cenozoic coarse sediment near them and palaeobotanical evidence for warmer climates where high mountain climates today are relatively cold have traditionally been interpreted as evidence for recent uplift an alternative cause of these phenomena is late cenozoic global climate change towards lower temperatures increased alpine glaciation a stormier climate and perturbations to humidity vegetative cover and precipitation

crustal evolution in south india constraints from nd isotopes nd isotope analyses from a range of lithologies including charnockites metasediments and granitoids that comprise the high grade terrain of south india define contrasting age provinces north of the palghat cauvery shear zone the karnataka craton and the granulite blocks of nilgiri and madras are characterized by model nd ages from 3 4 to 2 4 ga with significant crustal growth during the late archean south of the palghat cauvery shear zone a pan african granulite facies event resulted in sm nd fractionation as observed in several incipient charnockite localities model nd age calculations that allow for sm nd fractionation at 550 ma yield ages in the range of 2 9 to 1 3 ga this range compares closely with published model nd ages from the high grade terrain of sri lanka mid proterozoic crustal growth 1 1 ga observed in the vijayan complex of sri lanka may have provided source material for metasediments characterized by young model nd ages in southern peninsular india the palghat cauvery shear z

cordierite gneisses of southern kerala india petrology fluid inclusions and implications for crustal uplift history the cordierite bearing gneisses occurring as elongate patches in an 8 to 10 km wide zone along the achankovil fault lineament at the northern margin of the southern kerala crustal segment represent an important lithological unit in the archaean granulite terrane of south india the textural relationships in these rocks are consistent with the following main reactions 1 garnet quartz cordierite hypersthene 2 garnet sillimanite quartz cordierite 3 hypersthene sillimanite quartz cordierite 4 sillimanite spinel cordierite corundum and 5 biotite quartz sillimanite cordierite k feldspar many of the mineral associations and reaction textures including the remarkable preservation of symplectites are indicative of partial replacement of high pressure assemblages by cordierite bearing lower pressure ones during an event of rapid decompression temperature estimates from coexisting mineral phases show 710 garnet biotite 791 garnet cordierite and 788 c garnet orthopyroxene pressure estimates from mineral assemblages range from 5 4 to 7 kb detailed fluid inclusion studies in quartz associated with cordierite show high density co2 0 80 0 95 g cm3 as the dominant fluid phase with traces of probable ch4 in the sillimanite bearing rocks the isochore for the higher density fluid inclusions defines a pressure of 5 5 kb the fracture bound co2 and co2 h2o ch4 inclusions indicate simultaneous entrapment at 400 c and 1 7 kb in the cordierite hypersthene assemblage and 340 c and 1 2 kb in the cordierite sillimanite assemblage the p t path delineated from combined solid and fluid data corresponds to the piezothermic array of the gneisses and is characterized by t convex nature indicative of rapid and virtually isothermal crustal uplift probably aided by extensional tectonics

erosion driven uplift of the modern central alps abstract we present a compilation of data of modern tectono geomorphic processes in the central european alps which suggest that observed rock uplift is a response to climate driven denudation this interpretation is predominantly based on the recent quantification of basin averaged late holocene denudation rates that are so similar to the pattern and rates of rock uplift rates as determined by geodetic leveling furthermore a gps data based synthesis of adriatic microplate kinematics suggests that the central alps are currently not in a state of active convergence finally we illustrate that the central alps have acted as a closed system for holocene redistribution of sediment in which the peri alpine lakes have operated as a sink for the erosional products of the inner central alps while various hypotheses have been put forward to explain central alpine rock uplift e g lithospheric forcing by convergence mantle processes or ice melting we show with an elastic model of lithospheric deformation that the correlation between erosion and rock uplift rates reflects a positive feedback between denudation and the associated isostatic response to unloading thus erosion does not passively respond to advection of crustal material as might be the case in actively converging orogens rather we suggest that the geomorphic response of the alpine topography to glacial and fluvial erosion and the resulting disequilibrium for modern channelized and associated hillslope processes explains much of the pattern of modern denudation and hence rock uplift therefore in a non convergent orogen such as the central european alps the observed vertical rock uplift is primarily a consequence of passive unloading due to erosion

14c activity and global carbon cycle changes over the past 50 000 years a series of 14c measurements in ocean drilling program cores from the tropical cariaco basin which have been correlated to the annual layer counted chronology for the greenland ice sheet project 2 gisp2 ice core provides a high resolution calibration of the radiocarbon time scale back to 50 000 years before the present independent radiometric dating of events correlated to gisp2 suggests that the calibration is accurate reconstructed 14c activities varied substantially during the last glacial period including sharp peaks synchronous with the laschamp and mono lake geomagnetic field intensity minimal and cosmogenic nuclide peaks in ice cores and marine sediments simulations with a geochemical box model suggest that much of the variability can be explained by geomagnetically modulated changes in 14c production rate together with plausible changes in deep ocean ventilation and the global carbon cycle during glaciation

correlations of cave levels stream terraces and planation surfaces along the river mur timing of landscape evolution along the eastern margin of the alps the transition zone of the eastern alps to the pannonian basin provides one of the best sources of information on landscape evolution of the eastern alpine mountain range the region was non glaciated during the entire pleistocene thus direct influence of glacial carving as a landscape forming process can be excluded and relics of landforms are preserved that date back to at least the late neogene in this study we provide a correlation between various planation surfaces across the orogen basin transition in particular we use stream terraces planation surfaces and cave levels that cover a vertical spread of some 700 m our correlation is used to show that both sides of the transition zone uplifted together starting at least about 5 ma ago for our correlation we use recently published terrestrial cosmogenic nuclide tcn burial ages from cave sediments new optically stimulated luminescence osl ages of a stream terrace and u th ages from speleothems minimum age constraints of cave levels from burial ages of cave sediments covering the last 4 ma are used to place age constraints on surface features by parallelizing cave levels with planation surfaces the osl results for the top section of the type locality of the helfbrunn terrace suggest an early wurm development 80 5 3 7 to 68 7 4 0 ka the terrace origin as a penultimate gravel deposit in classical alpine terminology riss is therefore questioned u series speleothem ages from caves nearby indicate formation during marine isotope stages mis 5c and 5a which are both interstadial warm periods as osl ages from the terrace also show a time of deposition during mis 5a ending at the mis 5 4 transition this supports the idea of temperate climatic conditions at the time of deposition in general tectonic activity is interpreted to be the main driving force for the formation and evolution of these landforms whilst climate change is suggested to be of minor importance obvious hiatuses in miocene to pleistocene sediments are related to ongoing erosion and re excavation of an uplifting and rejuvenating landscape

grain size of fluvial deposits and late quaternary climate a case study in the po river valley italy by stacking the grain size data interpreted from many logs of borings down to 200 m deep in a sector of the po river valley we have obtained a curve of the clay silt fraction vs depth that matches the oxygen isotope curve of paleotemperatures for the late quaternary contour maps and plots for selected subzones show that the northern half of the study area is characterized by this correlation whereas the southern part adds only a random low amplitude noise to the curve the suggested dependence of grain size of fluvial deposits on climate in a part of the study area would provide an indirect way to date these not otherwise datable sediments allowing an evaluation of the sedimentation rates and of the total subsidence since the last interglacial

palaeoenvironmental and climatic inferences from the late early pleistocene lacustrine deposits in the eastern tiberino basin central italy within the neogene quaternary evolution of the mediterranean intermountain basins the eastern tiberino basin provides new multifaceted chronological biostratigraphic palaeoecological and palaeoenvironmental information appreciably improving the knowledge of palaeoenvironmental and climate conditions during the middle late matuyama chron late early pleistocene shallow to relatively deep lacustrine deposits and alluvial plain deposits magnetostratigraphically calibrated hold malacofaunas ostracofaunas and carpological remains as well as a pollen record palaeocarpological remains widely originated from the local azonal vegetation of waterlogged environments nonetheless some taxa show transitional morphology between possibly extinct pliocene pleistocene forms and living taxa the pollen record highlights a conifer dominated forest phase indicating a temperate wet interglacial period well aligned inside the schemes for the same latitudinal band the abundance of tree taxa currently absent from the italian peninsula points to pre jaramillo late early pleistocene biostratigraphical characters here compared to other sections from central italy and contributes to a better definition of modes and timing of their disappearance in southern europe malacofaunas and ostracods still with late early pleistocene features together with charophyte mark repeated fluctuations in energy temperature and chemical composition of water the overall record identifies an incipient diachronous cooling trend for the first time recognized in southern europe

subsurface magnetostratigraphy of pleistocene sediments from the po plain italy constraints on rates of sedimentation and rock uplift we used facies analysis to reconstruct the pleistocene sedimentary evolution of seven cores from the central northern po plain italy the cores record an overall regressive sequence consisting of shallow water marine and fl uvial deltaic deposits overlain by fully continental sediments we used magnetostratigraphy to date marine and fl uvial deltaic sediments to the early pleistocene and continental sediments to the middle late pleistocene sediment accumulation rates were 30 40 cm k y in the early pleistocene whereas relevant unconformities and or an overall reduction in sediment accumulation rates characterized the middle late pleistocene a simple airy compensation model was applied to restore actual sediments elevations to elevations at times of deposition expressed in meters above current sea level the correlation of isostatically corrected sedimentary facies to a sea level curve obtained from classic oxygen isotope studies shows that an event of rock uplift on the order of 70 120 m occurred in the middle late pleistocene literature studies of vegetational cyclicity used in conjunction with the sea level curve allowed us to link sedimentary facies to climate variability we propose that the onset of fully and persistently continental sedimentation occurred in response to the waxing of the fi rst major pleistocene glaciation in the alps currently correlated to marine isotope stage 22 at ca 0 87 ma and that the episode of uplift occurred at least in part as a consequence of erosion and crustal rebound of the alpine chain triggered by pleistocene glacialinterglacial cycles

vegetation change in a climatic cycle of early pleistocene age in the leffe basin northern italy abstract the plio pleistocene deposits of the leffe basin in the lombardian pre alps in italy first investigated in quarry and lignite mine shafts by lona in 1950 were recently cored the pollen record of part of this core reveals a sequence of four climatic cycles one of them which is about 1 6 ma old and particularly characteristic is discussed here a long interglacial stage can be identified by the dominance of pollen of deciduous trees of temperate climate it clearly shows a forest succession of a mixed oak forest of dry temperate climate followed by a strong development of a juglandaceae assemblage rich in arcto tertiary elements some of them indicating a wet climate in particular the carya peaks appear to be linked to a warm temperate 14 16 c mean annual temperature humid maritime climate with a long growth season if we compare them with modern and fossil analogs this stage is followed by a cooling leading to a long phase of wet coniferous forest this forest succession is subsequently interrupted by a brief period of open vegetation indicating a drier and colder continental climate followed by a new vegetational cycle the climate evolution is discussed in comparison with other recent pollen successions of uppermost pliocene age in the mediterranean area the cycle described is estimated to have lasted about 30 ka the entire leffe lacustrine succession records eight climatic cycles of moderate amplitude we suggest that this cyclicity has been induced by obliquity forcing correlation of the cold phases with the major glacial events of the southern alps as proposed by venzo 1950 and lona 1950 is excluded

a stalactite record of four relative sea level highstands during the middle pleistocene transition ice sheet and sea level fluctuations during the early and middle pleistocene are as yet poorly understood a stalactite from a karst cave in north west sicily italy provides the first evidence of four marine inundations that correspond to relative sea level highstands at the time of the middle pleistocene transition the speleothem is located 97 m above mean sea level as result of quaternary uplift its section reveals three marine hiatuses and a coral overgrowth that fixes the age of final marine ingression at 1 124 0 2 thus making this speleothem the oldest stalactite with marine hiatuses ever studied to date scleractinian coral species witness light limited conditions and water depth of 20 50 m integrating the coral constrained depth with the geologically constrained uplift rate and an ensemble of rsl scenarios we find that the age of the last marine ingression most likely coincides with marine isotope stage 35 on the basis of a probabilistic assessment our findings are consistent with a significant antarctic ice sheet retreat

isotope shifts in the late permian of the delaware basin texas precisely timed by varved sediments closely spaced samples 285 in number of varved sediments from the upper permian in delaware basin texas have been analyzed for 13ccarb 13corg 18ocarb corg ccarb and calcite dolomite 13c records a dramatic rise from 2 8 to 5 7 in only 4400 years detected in three sections across the basin extrapolating smoothly through a 600 year interruption by a local west side of the basin fresh water inflow evidenced by low 18o this continuity and low corg within the basin both indicate that the excess net deposition of corg necessary to generate the rise in 13c took place in the ocean external to the delaware basin correlation with similar records from the zechstein basin suggest that the event was world wide although this poses obvious difficulties for the carbon cycle the rate of rise of 13c and its sustained high level must imply conversions of oxidized carbon to reduced carbon that are very large depending on which reservoirs were involved

a new active tectonic model for the construction of the northern apennines mountain front near bologna italy 1 we integrate existing and new geologic data retreating trench extension and accretion tectonics retreat project particularly on the origin growth and activity of the mountain front at bologna italy into a new model that explains apennine orogenesis in the context of a slab rollback upper plate retreat process the bologna mountain front is an actively growing structure driving rock uplift 1 mm year cored by a midcrustal flat ramp structure that accommodates ongoing shortening driven by adria subduction at a rate of 2 5 mm year the data we use are assembled from river terraces and associated pleistocene growth strata geodesy including releveling surveys reinterpretation of published reflection lines and a new high resolution reflection line these data constrain a simple trishear model that inverts for blind thrust ramp depth dip and slip apennine extension is recognized both in the foreland as high angle normal faults and modest stretching in the carapace of the growing mountain front and in the hinterland with larger normal faults that accomplish some crustal thinning as the upper plate retreats this coevolution of extension and shortening shares some notable characteristics with other basement involved collisional orogens including the early tertiary laramide orogeny in the american west and the oligocene to miocene evolution of the alps we propose a possible relationship between underplating and the development of the po as a sag basin as a quaternary phenomenon that may also apply to past periods of apennine deformation tortonian continued shortening on the structure beneath the bologna mountain front represents by far the most important and underappreciated seismogenic source in the front of the northern apennines

hydrogeophysical imaging of alluvial aquifers electrostratigraphic units in the quaternary po alluvial plain italy the integration of surface geological and geomorphological information with borehole point data and geophysical e g geoelectrical images of the subsurface yields spatially consistent representations of alluvial aquifers heterogeneity at different scales from depositional systems to basin fills such an approach requires a conceptual framework to match the stratigraphic units with their evidence from ground based dc resistivity methods to effectively fill the gaps between sparse borehole data and to obtain valid representations of sedimentary heterogeneities such an approach is applied to characterize two sites of the quaternary aquifers of the central po plain italy which represent 1 the middle upper pleistocene braided to meandering river depositional systems sitting on southalpine crust and 2 their down current counterparts where they are involved by the latest uplift and deformation due to the tectonic activity of the apennine frontal thrusts electrical resistivity was considered as a proxy of the litho textural properties of hydrofacies and their major hierarchical association at depth and was interpreted in accordance with the depth decreasing resolution of ground based resistivity methods thus it was possible to identify the geophysical signature of hydrostratigraphic units through electrostratigraphic units i e sedimentary volumes identified by resistivity contrasts that spatially preserve the vertical polarity hydrostratigraphy and electrostratigraphy were then joined together through a site specific relationship between electrical resistivity and hydraulic conductivity which takes into account the prevailing process of current conduction the litho textural properties of hydrofacies and the groundwater electrical conductivity at the scales of aquifer systems and complexes this approach permitted to establish the conceptual framework to match hydrostratigraphy electrostratigraphy average hydrodynamic properties and distribution of heterogeneities

crustal uplift in the alps why the drainage pattern matters introductionmountain belts grow by accretion ofupper crustal material into the orogen icwedge fig 1 materialenteringthewedge gets deformed uplifted andexhumed basedontheoreticalmodels willett et al 1993 concluded thatorogensadoptadistinctgeometrywitha low tapered pro wedge facing thesubduction plate and a high taperedretro side this geometry establishesbecauseorogenstendtobeonthevergeof gravitational failure davis et al 1983 according to these models thevelocity eld of the crust and hence the exhumation path of rock particles depends on erosion at the surface e g horton 1999 consequently anychanges in erosion rates potentiallyresult in a modi cation of the patternof strain rates of surface erosion however depend on climate exposedlithologies the size of the catchmentarea thegeometriccon gurationofthedrainage basin and rates of crustaluplift tucker and slingerland 1996 although the impact of these para meters on surface erosion has beenstudied extensively using numericalmodels tucker and slingerland 1997 ku hni and p ffner 2001 schlu neggeret al 2001 verylittleattentionhas been paid to the in uence of thedrainage geometry on the spatial pat tern of erosion and on strain the central swiss alps provide anexample where the present daydrainage geometry reveals a distinctpattern that is characterized by largeorogen parallel dispersal systems therhone and rhine rivers fig 2a that drain the core of the alps and smaller orogen normal rivers according to the conceptual modelsoutlined above it is reasonable tospeculate that the asymmetry of thealpine drainage pattern is likely toin uence the pattern of crustal up lift speci cally the highest rates ofstrain release are expected in therhone and rhine valleys becausethe large drainage basins of theserivers are likely to result in enhancederosional potentials this hypothesiswill be tested in the following chap ters this present paper evaluates thepotential controls of the asymmetriccon guration of the alpine drainagepattern on possible variations oferosional potential as well as onpresent day and glacial sedimentyield this information is then rela ted to the published pattern ofcrustal uplift allowing possible pos itive feedback between surface ero sion and lithospheric forcing to beidenti ed the intention is not todiscard other processes as possiblecontrols on the pattern of crustaluplift e g exural rebound afterremoval of the pleistocene ice sheet kahle et al 1997 but rather topropose an alternative model thatmight enrich the range of possibleinterpretations pattern of crustal upliftand seismic activityfigure 2 a displays the recent verti cal movements of the swiss alpscomputed for rst order levellingbenchmarks relative to the benchmarkat aarburg gubler et al 1981 kahleet al 1997 the geodetic data wascollected repeatedly between c 1905and 1990 measured uplift is inter preted in terms of crustal upliftbecause benchmarks have not experi enced erosion i e they record theshort term velocity eld of upper most crustal levels the data indicatea considerable increase of crustaluplift rates from the foreland tothe rear of the alps where currentrates of 1 mm yr

long period amplification in deep alluvial basins and consequences for site specific probabilistic seismic hazard analysis an example from the po plain northern italy this study deals with the impact of deep soil discontinuities on ground motion amplification in the po alluvial basin northern italy and consequently on long period probabilistic seismic hazard analysis estimates the focus is on castelleone where a seismic station of the italian national seismic network has been deployed since 2009 to define a detailed shear wave velocity v s profile extensive active and passive geophysical surveys were carried out the active measurements included seismic profiles examined through standard refraction techniques and multichannel analysis of surface waves the passive methods included ambient vibration measurements in both single and array configurations in particular three microtremor arrays with increasing apertures were performed to capture the experimental dispersion curve down to 0 2 hz the horizontal to vertical spectral ratio hvsr showed two main peaks at 0 17 and 0 70 hz a joint inversion of the experimental phase velocity dispersion and hvsr curves was performed to obtain the v s profile the data show two main discontinuities at 160 and 1350 m in depth according to the italian and european seismic codes the shallow v s discontinuity can be ascribed to the seismic bedrock i e v s 800 m s whereas the deeper one is observed at the transition between pliocene quaternary deposits and miocene marls preliminary site specific seismic hazard analysis in terms of displacement response spectra for periods up to 10 s shows that neglecting the effects of the deeper discontinuity implies underestimation in hazard estimates of up to about 49 for mean return period mrp of 475 years and about 57 for mrp of 2475 years with possible consequences regarding the design of very tall buildings and large bridges

insights on the opening of the galerian mammal migration pathway from magnetostratigraphy of the pleistocene marine continental transition in the arda river section northern italy abstract we investigated the magnetostratigraphy of the arda river section northern italy where the transition from marine to continental sedimentation occurring in the po river basin during the pleistocene is registered four magnetic polarity reversals were used to construct an age model of sedimentation aided by marine biostratigraphy and tied to a standard 18o curve from the literature the section spans from the olduvai subchron 1 94 1 78 ma across the jaramillo subchron 1 07 0 99 ma up to the brunhes matuyama boundary 0 78 ma the onset of continental deposition occurred during marine isotope stage mis 30 at 1 04 ma an association of villafranchian and early galerian mammals including sus strozzii and ursus dolinensis has been found in the continental sediments dated to mis 29 27 0 99 ma above follows a prominent fluvial conglomerate attributed to the first major lowstand of the pleistocene culminating with mis 22 at 0 9 ma during the late early pleistocene climate turnover ept these and other data from the literature are used to reconstruct the onset of continental deposition in the greater po basin and shed light on the opening of the migration pathway that brought far traveled galerian mammal immigrants to enter europe for the first time during the ept

continental depositional systems of the quaternary of the po plain northern italy abstract the po plain is a molasse foredeep bounded by two mountain chains apennines and alps apenninic thrusting is still active whereas the alpine one ended by early pliocene times the continental deposits form a veneer at the surface and form the topset of a prograding complex the po river divides the plain into two sectors with different sedimentary facies and body geometries to the south the alluvial fan and plain deposits are small embedded in clays and show elongate shapes to the north sedimentary bodies are laterally extensive tabular and with minor amounts of fine grained sediments this difference could be due to a different climatic conditions during quaternary ice ages on the two sides of the basin b different structural settings in the two sectors of the basin that produce a higher subsidence rate to the south c different lithologies in the source areas i e alps and apennines

quaternary erosion induced isostatic rebound in the western alps the high elevation and deep incision of the alps have traditionally been used as an argument for recent tectonic activity that has elevated the belt and increased erosion rates normal faulting and horizontal extension however dominate current tectonic activity and isostatic compensation of thinning crust should lead not to increased but to decreased mean elevations here we test the idea that enhanced quaternary erosion of the alps and isostatic compensation of the mass removed can account for the distribution of present day geodetically measured rates of vertical movement in the western alps using geophysical relief and kuhlemann s estimated average erosion rate for the alps we quantify the spatial distribution of erosion and the volume of eroded rock respectively from these we obtain a map of rock eroded within a given time span the calculated isostatic response of the alpine lithosphere to erosional unloading for a variety of values of the flexural rigidity of the alpine lithosphere reaches a maximum of 500 m since 1 ma in the inner swiss alps and vertical movement extends across the entire belt including peri alpine basins assuming a steady erosion rate since 1 ma this rebound accounts for half of the measured vertical motion of 1 1 mm yr in the southern valais thus a significant fraction 50 of the present day vertical movement results from the isostatic response to enhanced erosion during plio quaternary time

a petrogenetic grid for pelitic schists in the system sio 2 al 2 o 3 feo mgo k 2 o h 2 o a quantitative petrogenetic grid for pelitic schists in the system kfmash that includes the phases garnet chlorite biotite chloritoid cordierite staurolite talc kyanite andalusite sillimanite and pyrophyllite with quartz h2o and muscovite or k feldspar in excess is presented the grid is based on thermodynamic data of berman et al 1985 and berman 1988 for endmember kfash and kmash equilibria and natural fe mg partitioning for the kfmash system calculation of p t slopes and the change in fe fe mg along reactions in the kfmash system were made using the gibbs method in addition the effect on the grid of mno and cao is evaluated quantitatively the resulting grid is consistent with typical buchan and barrovian parageneses at medium to high grades at low grades the grid predicts an extensive stability field for the paragenesis chloritoid biotite which arises because of the unusual facing of the reaction chloritoid biotite quartz h2o garnet chlorite muscovite which proceeds to the right with increasing t in the kfmash system however the reaction proceeds to the left with increasing t in the mnkfash system so the assemblage chloritoid biotite is restricted to bulk compositions with high fe fe mg mn typical metapelites will therefore contain garnet chlorite at low grades rather than chloritoid biotite

possible late middle ordovician organic carbon isotope excursion evidence from ordovician oils and hydrocarbon source rocks mid continent and east central united states oils generated by middle ordovician rocks are found throughout the mid continent and east central regions of the united states gas chromatographic characteristics of these oils include a relatively high abundance of n alkanes with carbon numbers less than 20 a strong predominance of odd numbered n alkanes between c10 and c20 and relatively small amounts of branched and cyclic alkanes saturated and aromatic hydrocarbon fractions of 43 ordovician oils from the anadarko ardmore forest city illinois michigan salina sedgwick and williston basins and the iowa shelf demonstrate a wide range in carbon isotope composition dgr13csat 24 9 pmil to 33 9 pmil dgr13carom 24 3 pmil to 33 7 pmil saturated and aromatic hydrocarbons extracted from late middle ordovician shales 17 core samples show ranges in dgr13c similar to that of the oils the wide ranges in dgr13c for oils and rock extracts reflect a major positive excursion s 6 9 per pmil in organic matter dgr13c in late middle ordovician rocks this excursion has at least a regional significance in that it can be documented in sections 480 mi 770 km apart in south central kansas and eastern iowa the distance may be as much as 930 mi 1 500 km if the carbon isotope variations observed in michigan basin ordovician oils and in organic matter from late middle ordovician rocks in southwestern ontario are related to the same carbon isotope excursion organic matter dgr13c in core samples from south central kansas and eastern iowa is not directly related to variations in quantity or quality of organic matter or maceral compositi n the positive excursion in organic matter dgr13c is a possible result of increased organic matter productivity and or preservation the parallel shifts in organic and carbonate dgr13c in core samples from 1 e m greene well washington county iowa imply changes in the isotope composition of the ocean atmosphere carbon reservoir differences in the magnitude of the carbon isotope shifts between organic matter 8 8 pmil and carbonate 4 2 pmil in this core suggest a decrease either locally or regionally in available dissolved co2 possibly a result of high organic matter productivity and or limited circulation in the late middle ordovician seas

precambrian tectonics and crustal evolution in south india about 3 4 ga ago voluminous calc alkaline magmas represented by the granitoid gneisses of southern india were emplaced into a now poorly preserved non continental crust unstable ensialic basins initiated at about 3 0 ga were filled with volcanic and sedimentary rocks up to about 2 6 ga this basement cover sequence was deformed at the close of the archaean first by northward accretion and thickening of several crustal slabs formerly separated by prisms of stable shelf sediments structures produced by this episode were refolded and dislocated by large n s strike slip shear belts to impart intense steep planar fabrics to large volumes of the crust fluids rich in co possibly derived from sedimentary material driven beneath the crustal slabs by the thickening mechanism purged the deep crust of h o to form granulites upward migration of hot h o rich fluids encouraged partial melting at intermediate crustal levels these late archaean tectonic and thermal events began soon after the close of basin f

late neogene erosion of the alps a climate driver as with many mountain belts globally the alps have seen a large increase in sediment yield in the late neogene the hypothesis that this increase results from climate change impacts on erosion rate over the past 5 ma is testable given the extensive work completed in the alps sediment budgets thermochronology based cooling rates and estimates of modern rock uplift and erosion in the western alps are reviewed to search for correlation in space and time that might fingerprint climatic events major increases in sediment yield are apparent starting in the late messinian 5 5 mya and accelerating toward the present day this suggests the occurrence of a series of climatic changes that increased erosion rates even as tectonic processes appear to have slowed or stopped at present tight correlations in time are difficult to establish and there remain open questions about the role of tectonics in the coupled system

a calculated petrogenetic grid for the system k2o feo mgo al2o3 sio2 h2o with particular reference to contact metamorphosed pelites a petrogenetic grid is presented for the system kfmash k o feo mgo a1 0 sio h o including biotite muscovite k feldspar chlorite chloritoid staurolite cordierite garnet ortho amphibole orthopyroxene spinel andalusite sillimanite kyanite quartz and corundum with h o in excess which was calculated using the computer program thermocalc and the powell and holland internally consistent thermodynamic dataset by removing the normal constraint of having quartz in excess both quartz bearing and quartz absent equilibria are shown quartz absent equilibria are particularly relevant at high t and low p conditions because of their common occurrence at these conditions the calculated mineral assemblage and mineral compositional variations in terms of femg and fe mg siall exchange vectors are broadly compatible with observations on natural rocks particularly when non kfmash components are taken into account

variable fault tip propagation rates affected by near surface lithology and implications for fault displacement hazard assessment abstract the fabric of reverse fault zones close to the surface is usually partitioned in between a narrow discrete rupture zone and a more distributed one where folding is predominant this makes quite challenging the adoption of proper setbacks in surface rupture hazard studies for critical facilities or microzoning some of the parameters controlling fault zone fabric are related to mechanics of near surface geology lithology overburden thickness cohesion and water content whose interaction is complex and only partially understood nevertheless these can be seldom measured or derived kinematic models conversely express such an interaction of complex variables as simple synthetic parameters such as the amount of upward propagation of the fault tip for unit of slip usually referred to as the p s ratio propagation on slip here we discuss results on the trishear kinematic inverse modeling of a contractional fault propagation fold at monte netto hill capriano del colle n italy observing a two stage fault and fold growth evolution marked by a significant shift in the p s parameter at this site exceptional sequence of exposures due to ca 10 years of quarry excavations allowed to obtain a series of cross sections across the fault zone we use this detailed high resolution example as a natural analogue for more general large scale surface ruptures involving a thick alluvial cover a very common setting for the siting of critical facilities during the early stage of displacement the fault cut through clast supported fluvial gravels with a high propagation rate p s 7 and a discrete rupture width then during the latest movements of the thrust fault tip propagation slowed down to p s 2 9 as the fault started cutting through several stacked bodies of clays and silty clays pedogenized aeolian silts and overbank deposits causing a pronounced folding of the layers over a wider deformation zone these results strongly suggest that lithological changes in the underlying shallow stratigraphy common in an alluvial plain depositional setting would significantly affect the potential for surface faulting across the same tectonic structure with relevant implications in the fault displacement hazard assessment

an electrostratigraphic cross section across the central po plain bearings on subsurface geology and hydrostratigraphy a 72 km long n s cross section was surveyed with direct current resistivity soundings through the quaternary clastic infill of the apennine foredeep in the po plain of lombardy northern italy the aims are 1 to test the potential of dc resistivity methods at the regional scale 2 to draw the electrostratigraphic picture of the basin fill down to the pre quaternary substratum 3 to refine and test the methodology and concepts of hierarchic electrostratigraphy at the basin scale 4 to contribute to characterize the regional hydrostratigraphy of a relevant hydrogeological basin 163 resistivity versus depth profiles with a maximum investigation depth of 450 m were obtained from vertical electrical soundings to draw the electrostratigraphic cross section the polarity of the resistivity contrast across resistivity interfaces i e resistive over conductive layers or vice versa was considered and the discontinuities were correlated according to the persisting pattern from north to south doing so the hierarchic assemblage of four major electrostratigraphic boundaries and the five intervening groups of electrostratigraphic units esus was established the resulting picture was compared to the available subsurface reconstructions from the literature using the 1 d borehole data only to check the geophysical image at some random sample sites the results show that the electrostratigraphic picture captures the geological and hydrostratigraphic complexity of the subsurface of the basin comparing well with the available direct subsurface geological and hydrostratigraphic reconstructions at the regional scale of the cross section two hierarchic orders of esus and correlative boundaries could be drawn first order groups and second order individual esus while the lowermost third order rank the electrolayer is recognized at the single ves sites only

palaeoenvironment and carbon isotope stratigraphy of upper proterozoic carbonates of the yangtze platform the 13c values for phanerozoic marine carbonates display secular trends mainly in the range 1 to 2 1 these have been interpreted as primary features reflecting changes in the carbon isotope composition of dissolved bicarbonate in seawater brought about largely by variations in the proportions of carbon being sequestered in the oxidized and reduced carbon reservoirs1 2 carbon isotope trends are not as well established for the precambrian but there are indications that upper proterozoic sequences contain carbonates with unusually high 13c values3 9 here we present the results of the first carbon isotopic study of the upper proterozoic carbonate strata from the type locality of the sinian system in the yangtze gorges sections near yichang south china and discuss their implications for accumulation of organic matter we also compare the results for these chinese strata with 13c trends in other upper proterozoic cambrian sequences and assess the extent to which such isotopic data can be used to make stratigraphic correlations between widely spaced sequences

reconstructing the palaeoenvironments of the early pleistocene mammal faunas from the pollen preserved on fossil bones abstract we carried out a systematic investigation on the pollen content of sediment adhering to skeletal elements of large mammals which originate from the long lacustrine record of leffe early pleistocene of the italian alps three local faunas were discovered during mining activities along the intermediate part spanning from 1 5 to 0 95 ma of the basin succession the excellent pollen preservation allowed testing the reproducibility of the pollen signal from single skeletons a clear palaeoenvironmental patterning consistent with the ecological preferences of the considered mammal species emerged from the canonical correspondence analysis of pollen types diagnostic for vegetation communities edaphic factors related to seasonal river activity changes and to the development of swamp forests in the riverbanks are significantly associated to the occurrences of hippopotamus cf antiquus whereas finds of mammuthus meridionalis belong to fully forested landscapes dominated by conifer or mixed forests of oceanic warm to cool temperate climate rhinoceros habitats include variable forest cover under different climate states distinct cool temperate partially open vegetation could be recognized for large deer included cervalces cf carnutorum a palynostratigraphic correlation between individual spectra and a reference palynostratigraphic record allowed assignment of many fossil remains to a precise stratigraphic position this procedure also shown that the leffe local faunas include specimens accumulated under different environmental and climate states as a consequence of high frequency climate changes characterizing the late villafranchian early pleistocene

stratigraphic evidence of a middle pleistocene climate driven flexural uplift in the alps 1 this interdisciplinary study on the subsurface stratigraphy of the po plain northern italy brings new evidence in support of a climate driven erosional unloading of the alps since the middle pleistocene a newly acquired high resolution seismic profile and a critical review of industrial seismic lines were integrated with sedimentologic observations on four magnetostratigraphically dated continental cores to reconstruct a three sequence evolution of the pleistocene clastic infill in the northern po basin during the first sequence ps1 1 4 0 87 ma characterized by sedimentation rates of 34 cm kyr outpacing regional subsidence meandering river systems prograded over the basin passing downstream to a cyclothemic shelfal succession the second sequence ps2 0 87 0 45 ma heralded by a regional unconformity r surface correlated to the onset of the major pleistocene glaciations was characterized by widespread continental sedimentation of generally distal braidplain the third sequence ps3 0 45 ma to present marked at the base by another regional unconformity y surface is characterized by proximal braided fluvial deposition under combined conditions of confinement erosion and bypass we interpret the ps3 sequence as deposited under the effects of a flexural uplift of the northern po plain during the middle pleistocene starting at 0 45 ma in response to the long term erosional unloading of the alps triggered by the waxing and waning of alpine glaciers since the late early pleistocene global cooling 0 9 ma according to our modeling erosion on a relatively limited area of the alpine mountain chain ranging from 1 3 to 1 7 mm yr in the axial sector to 0 1 0 3 mm yr at the margins has been able to trigger rock uplift over a wider area including the proximal peripheral basins

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

late quaternary sequence stratigraphy as a tool for groundwater exploration lessons from the po river basin northern italy sequence stratigraphy typically used for hydrocarbon exploration in ancient strata can be applied to late quaternary successions to decipher complex spatial relations among their aquifers late pleistocene holocene strata of the po basin were investigated using a sequence stratigraphic approach to produce a high resolution model for guiding groundwater exploitation because facies tend to be diachronous across depositional basins facies analysis was done within the conformable intervals of strata revealed by sequence stratigraphy to accurately interpret and map coeval lateral facies relations volumetric assessments sand distribution mapping hydraulic characterization of facies and spatial variations of hydraulic parameters revealed two aquifer systems the lowstand systems tract lst and the highstand systems tract hst vertically separated by an aquitard the transgressive systems tract tst the lst aquifer consists of amalgamated fluvial sands average transmissivity 3 5 e 3 m2 s 37 7 e 3 ft2 s with considerable width 25 km 16 mi preferentially elongated downstream the widespread tst aquitard is dominated volumetrically 57 by low permeability estuarine deposits the hst aquifer average transmissivity 5 4 e 5 m2 s 58 1 e 5 ft2 s is 5 10 km 3 6 mi wide elongated parallel to the modern shoreline sequence stratigraphic analysis at the parasequence scale revealed an almost unprecedented level of detailed insight into aquifer or aquiclude dimensions and the complex distribution of hydraulic parameters in the subsurface showing that similar facies have different permeabilities depending on systems tract in contrast lithostratigraphic mapping obscures subsurface connectivity and directional trends and has minimal predictive power away from control these insights should be useful for guiding correlation and mapping of the deep subsurface and for hydrocarbon reservoir modelers

progressive offset and surface deformation along a seismogenic blind thrust in the po plain foredeep southern alps northern italy here we present for the first time in the po plain foredeep northern italy the middle to late pleistocene growth history of an outcropping secondary fold and related faults whose progressive deformation over an intermediate time window 105 years is driven by an underlying seismogenic blind thrust we trenched and logged an outcropping decametric secondary anticline related to a deeper blind compressional structure which deforms fluvial sediments and an overlying loess paleosol sequence folded units were dated using radiocarbon and optically stimulated luminescence methods to the late pleistocene holocene and tentatively correlated with glacial interglacial phases occurring during the time interval from marine isotope stage 6 to the present a multistep retrodeformation of the fold allowed us to calculate uplift rates for this secondary and shallow anticline varying between 0 02 and 0 1 mm yr since circa 200 kyr trishear forward deformation modeling of the fold indicates that the amplification of the observed fold could be caused by two shallow thrusts formed through a break backward activation this generated a decametric surface fold whose most recent growth was associated with bending moment normal faulting in the crestal and forelimb region our observations demonstrate that near surface compressive tectonics can be caused by blind thrusting via a complex array of fault and folds upward strain propagation and generation of shallow low angle thrust and related folding seem to be mainly due to secondary fold related faulting according to an out of syncline thrusting mechanism

teleseisms as estimators of experimental long period site amplification application to the po plain italy for the 2011 mw 9 0 tohoku oki japan earthquake abstract this study focuses on the evaluation of teleseisms as estimators of long period seismic site amplification in correspondence to large alluvial basins using the recordings of the 11 march 2011 m w 9 0 tohoku oki japan earthquake the site response at low frequency of the po plain italy was investigated the interdistances among the analyzed sites compared to the travel paths of the tohoku oki waveforms with respect to the target area allowed us to investigate the reliability of the standard spectral ratio ssr technique applied to teleseismic recordings the results are presented as directional ssrs calculated considering 2 min of p s and rayleigh lr waves filtered from 0 025 to 1 0 hz considering the horizontal components at frequency from 0 04 to 0 3 hz the po plain stations show amplification factors up to 20 and 16 detected for the s and lr phases respectively in some cases the amplified ground motion appeared to be affected by polarization phenomena in particular in the north south direction moving from the center to the edge of the basin the lr wave amplification remarkably decreases in particular for frequencies between 0 1 and 0 3 hz this was not observed for the s wave amplification factors 10 were also detected for the vertical component with increasing resonance periods moving from p to lr waves comparing ssrs with the single station horizontal to vertical spectral ratios the latter case shows that the vertical amplifications lead to the partial masking of the actual response of a site in particular for frequencies 0 15 hz finally the relative p wave amplitudes were also investigated the results of the spectral analysis and the correlation between the relative p wave amplitudes and the geometry of the bedrock suggest that the proposed approach is appropriate for the investigation of long period seismic site response in similar settings

tectonic controls of phanerozoic sedimentary rock cycling the cyclic nature of the phanerozoic sedimentary rock distribution carbon sulphur coupling and material transfer among sedimentary reservoirs appears to be controlled by tectonic factors the distribution of preserved sedimentary mass in terms of rock mass remaining u geologic age shows a minimum c 300 350 ma ago which separates two subcycles of erosion and deposition of sedimentary rocks the older subcycle was interrupted because of the major continental collisions of the devonian and late carboniferous these collisions resulted in a reduction of outcrop areas of rocks of the older cycle relative to their masses leading to a decline in the probability of destruction and an increase in half life of these older sediments a strong correlation exists between the long term cyclicity in the phanerozoic global sea level curve and the distribution of carbon and sulphur among their major exogenic reservoirs this correlation is related to two principal tectonic modes of the phanerozoic oscillatory and submergent it is postulated that the submergent mode of active plate convergence obduction and subduction of sediments large ridge volume and high sea level gave rise to low erosion and sedimentation rates less restricted environments of carbonate deposition and relatively high atmospheric co 2 levels high temperatures resulting from an increased rate of production of co 2 from diagenetic and metamorphic reactions at subduction zones as sea level rose carbon was transferred from the sedimentary reservoir of reduced organic carbon to that of oxidized inorganic carbon in limestones whereas sulphur moved from the oxidized sulphate reservoir to the reduced sulphide reservoir as sea level fell reservoir transfers were opposite to those above culminating in the oscillatory mode of generally elevated continental interiors these reservoir transfers are consistent with secular changes observed in the distribution of 13 c and 34 s in sedimentary materials during the phanerozoic petrographic examination of phanerozoic oolite formations shows that ooids with preserved calcitic relict textures are characteristic of pre carboniferous carbonate rocks whereas ooids with relict textures indicative of initial aragonite mineralogy are dominant in rocks of younger age these changes in ooid mineralogy may be interpreted as reflecting changes in co 2 levels of the ocean atmosphere system consistent with the above tectonic considerations atmospheric co 2 levels were higher prior to carboniferous time favouring formation of calcitic ooids and skeletal parts after the carboniferous co 2 levels fell and aragonite and mg calcites of greater than 8 mol mg increased in abundance as precipitates

climate induced rebound and exhumation of the european alps foreland basins record the regional isostatic compensation of mountain belts during periods of crustal thickening they subside and when erosion unloads the mass of the mountains the basins rebound and are eroded in order to evaluate this mechanism for rebound it is critical that the timing and magnitude of erosion are documented we present data estimating the timing and magnitude of late orogenic or postorogenic erosion in the north alpine foreland basin of switzerland mineral cooling ages demonstrate that the basin underwent 1 3 km of erosion soon after 5 ma this erosion coincided with a decline in structural deformation in the swiss alps and a doubling of sediment accu mulation rates in surrounding depocenters we propose that accelerated erosional un roofing of the swiss alps triggered isostatic rebound and erosion of the foreland basin after 5 ma a projection of the isostatic rebound of the basin into the mountains suggests that at least 6 5 km of erosion should have occurred in the high topography of the aar massif accelerated erosion in the swiss alps at that time is explained by an increase in atmospheric moisture driven by an intensification of the atlantic gulf stream at 4 6 ma consequently we propose that the changing erosional capacity of the climate triggered late orogenic to postorogenic mass reduction and isostatic rebound of the swiss alps and their neighboring foreland basin

melt producing and melt consuming reactions in the achankovil cordierite gneisses south india migmatitic cordierite gneisses within the achankovil zone az of southern pan african india record melt producing and subsequent melt consuming mineral reactions early mineral assemblages bt sil qtz and bt sil spl deduced from inclusion textures in garnet prophyroblasts break down via successive dehydration melting reactions to high t phase assemblages e g grt crd liq opx liq spl crd liq later back reactions between the restite and the in situ crystallizing melt resulted in thin cordierite coronas separating garnet from the leucosome and partial resorption of garnet to opx crd or crd bt qtz symplectites leucosomes generally display a moderate low strain gneisses to strong high strain gneisses depletion of alkali feldspar attributed to mineral melt back reactions partly controlled by the degree of melt segregation using a kfmash partial petrogenetic grid that includes a melt phase and qualitative pseudosections for microdomains of high and low al si ratios the successive phase assemblages and reaction textures are interpreted in terms of a clockwise p t path culminating at about 6 7 kbar and 900 950 c this p t path is consistent with but more detailed than published results which suggests that taking a melt phase into account is not only a valid but also a useful approach comparing p t data and lithological and isotopic data for the az with adjacent east gondwana fragments suggests the presence of a coherent metasedimentary unit exposed from southern madagascar via south india az and sri lanka wanni complex to the lutzow holm bay in eastern antarctica

evidence for late alpine tectonics in the lake garda area northern italy and seismogenic implications we investigated the recent evolution of the po plain alps system by integrating subsurface geophysical data from the po plain with new stratigraphic and structural observations from the southern alps margin inversion of structural data and chronology provided by stratigraphic constraints led to the definition of three tectonic events since the pliocene namely the intra zanclean the gelasian and the middle pleistocene driven by an axis of maximum compression formerly oriented ne intra zanclean and then to the nnw gelasian and middle pleistocene the associated deformation has been accommodated by two sets of faults consisting of nne trending thrust faults mostly represented in the western sector of lake garda and nw trending strike slip faults observed in the southern and eastern sectors the interplay between these two sets of faults is interpreted to produce short w w 6 5 along the nw trending strike slip faults in this framework the newly defined nogara fault and the sant ambrogio fault all pertaining to the nw trending system are regarded as potential candidates for the seismogenic source of the january a d 1117 event the most destructive earthquake in the po plain

variable late neogene exhumation of the central european alps low temperature thermochronology from the aar massif switzerland and the lepontine dome italy 1 several recent studies proposed an important increase in exhumation rate in the western european alps since circa 5 4 ma in order to assess potential spatial differences in exhumation histories we present new apatite fission track aft and apatite u th he ahe ages from the central aar massif guttannen area switzerland and the western lepontine dome formazza area italy internal u th zoning in apatites explains alpha ejection corrected ahe ages that are older than the corresponding aft ages in this study a qualitative interpretation of aft and ahe age elevation relationships suggests a two phase 9 7 and 5 3 ma exhumation scenario affecting the central alps with a stronger expression of the pliocene signal in the formazza area however a quantitative evaluation of exhumation scenarios using the 3 d heat equation solver pecube highlights the existence of several other likely scenarios casting doubt on the validity of a qualitative interpretation of the age elevation relationships in formazza scenarios suggested by quantitative modeling include continuous denudation at a rate of 750 m ma and a one step exhumation rate change from 300 to 1000 m ma at 5 ma in guttannen they include continuous denudation at a rate of 400 m ma with valley deepening and two periods of higher exhumation rate increasing from 300 to 700 m ma repeatedly at 9 7 and at 5 3 ma contingent upon further flexural isostatic modeling the magnitude of exhumation recorded in the axial region of the alps since circa 5 ma does not appear sufficient to solely explain the denudation recorded in the north alpine foreland basin

an active deformation structure in the po plain n italy the romanengo anticline field surveys well data and a detailed interpretation of a depth converted seismic line reveal that the romanengo high an isolated low relief that interrupts the morphological continuity of the po plain n italy west of the oglio river coincides with a partially buried anticline still active in recent times romanengo anticline the pliocene to holocene evolution of the structure has been reconstructed by sequential restoration based on combined decompaction and unfolding methods from the early pliocene to holocene the analysis shows that from the beginning of the pliocene onward periods of tectonic activity have alternated with periods of quiescence the more significant tectonic uplift rates are recorded during the late pliocene 0 33 0 06 mm yr and the beginning of calabrian 0 284 0 12 mm yr while at the end of calabrian the structure was virtually inactive during the early pleistocene the reversal in the vergence of the structure indicates the onset of interaction with the apennines deformational front in the area from middle pleistocene to holocene a marked increase in the tectonic uplift has been recorded with an uplift rate of about 0 12 0 05 mm yr a preliminary evaluation of the seismic hazards connected to blind thrusts affecting this active frontal sector of the alpine chain where it collides with the apennines buried deformation fronts is finally discussed

increase in late neogene denudation of the european alps confirmed by analysis of a fission track thermochronology database abstract a sharp increase in deposited sediment volume since pliocene times has been observed worldwide and in particular around the european alps this phenomenon has been linked to a rise in denudation rates controlled by an increase of either climatic or tectonic forcing observation of in situ cooling histories for orogens is critical to assess the reality of the inferred increase in denudation rates and to determine whether this phenomenon is widespread or localized at active tectonic structures we exploit the unique density of fission track ages in the western european alps to reconstruct cooling isoage surfaces and to estimate exhumation rates on the orogen scale between 13 5 and 2 5 ma our novel technique is based on the association of isoage contours with age elevation relationships it uses map view interpolation enabling a spatio temporal analysis of exhumation rates over the entire western alps the resulting exhumation histories reconstructed for eight areas of the western alps display strong similarities in timing and rates with orogen wide average denudation rates inferred from sediment volumes this consistency validates the use of both techniques for the study of an orogen characterized by strong relief and high recent exhumation rates we conclude that exhumation rates in the western alps have increased more than twofold since late miocene times this increase may have been locally modulated by the distinct response of different tectonic units

age of mammuthus trogontherii from kostolac serbia and the entry of megaherbivores into europe during the late matuyama climate revolution abstract at the drmno open pit coal mine near kostolac in serbia a nearly complete skeleton of mammuthus trogontherii nicknamed vika was discovered in a fluvial deposit overlain by a loess paleosol sequence where a second paleontological level named nosak with remains of m trogontherii was found we studied the magnetostratigraphy of the kostolac sedimentary sequence and found that the vika layer dates to 0 8 ma shortly before the brunhes matuyama boundary in addition according to our age model and previously reported optically stimulated luminescence and electron spin resonance dates the nosak fossils have an estimated age of 0 19 ma and lived during the earliest part of marine isotope stage 6 it appears therefore that at kostolac m trogontherii is preserved both at its earliest occurrence at 0 8 ma and close to its latest occurrence at 0 19 ma and may well have been present in between albeit not yet found we speculate that megaherbivores such as m trogontherii entered europe along a conjunct danube po river migration conduit connecting western asia levant with central southern europe where vast and exploitable ecosystems particularly suited for steppe or savanna adapted megaherbivores from asia and africa developed during the late early pleistocene climate revolution at around 0 8 ma