river terrace systems in north west europe an archive of environmental change uplift and early human occupation abstract staircases of large scale aggradational river terraces are a notable feature of many valleys in the temperate lattitudes particularly in areas beyond the reach of the erosive activities of pleistocene ice sheets it is now recognized that the cyclic fluctuations of climate during the quaternary have driven the generation of terraces through the direct and indirect influence of both temperature and precipitation on fluviatile activity where fossiliferous deposits are preserved within terrace sequences it is often possible to date these and to correlate them with the oceanic record thus providing an important framework for the evidence of environmental change on land middle and late pleistocene terraces in different areas can commonly be seen to have formed in synchrony with glacial interglacial cycles or with longer periodicity megacycles climatic forcing alone is insufficient to cause terraces to form however uplift is also necessary so that terrace sequences can provide a useful record of crustal movement in northwest europe where some of the best known studies of river terrace sequences have been carried out the fluviatile deposits are also an important repository for palaeolithic artefacts from which a record of early human occupation can be reconstructed

active stress map of italy we present a new map of the present day stress field in italy obtained from all the available data the map reports 200 horizontal stress directions inferred from 109 borehole breakout data 44 centroid moment tensor solutions 34 other focal mechanisms most of which are from polarity distributions seven stress inversions of microearthquake data two averages of t and p axes of earthquake focal mechanisms in zones of diffuse seismic activity and four fault slip data the integration of breakout data which yield horizontal stress directions with fault plane solutions which reflect the stress regime allows us to obtain an improved map of the present day stress in italy this stress field map can be used for a better comprehension of active tectonic processes for seismic hazard assessment and to foresee the behavior of faults recognized with other methods stress directions obtained from different data although relative to different depth intervals e g 0 7 km for breakouts and 0 20 km for most of the earthquakes and to different tectonic units are consistent since many regions in italy are characterized by an extensional stress regime we report the minimum horizontal stress shmin orientations the map shows that an extensional regime affects most of the apenninic belt conversely a compressional or transpressional regime characterizes the eastern alps the eastern side of the northern apennines and the southern tyrrhenian to northern sicily zone an abrupt change in stress directions marks the transition between northern and southern apennines suggesting that the two arcs are characterized by a different tectonic setting and recent evolution in this paper we report all the data analyzed to date with their geographic coordinates and average stress directions and we describe the main stress provinces in italy in the framework of the tectonic evolution of the region

the mw 5 4 reggio emilia 1996 earthquake active compressional tectonics in the po plain italy summary we have analysed the seismic sequence that occurred in october 1996 near the town of reggio emilia on the southern edge of the po plain the onset of the sequence was marked by a 5 4 moment magnitude main shock located at 15 km depth the main shock focal mechanism is a reverse solution with a strike slip component and the scalar moment is 1 46 1017 n m we used broad band digital recordings from a borehole station located at about 70 km from the epicentre for a spectral analysis in order to estimate attenuation and source parameters for the main shock in addition the empirical green s function method has been applied to evaluate the source time function in terms of both moment rate and stress rate we infer an asperity like rupture process for the main shock as suggested by the short duration of the stress release with respect to the overall duration of the moment rate function this analysis also allows us to estimate the average dynamic stress drop of the main shock 600 bar we analysed the digital recordings of the temporary local seismic network deployed after the main shock and of a permanent local network maintained by the italian petroleum agency agip during 15 days of field experiments we recorded more than 800 aftershocks which delineate a 9 km long ne elongated distribution confined between 12 and 15 km depth suggesting that the basement is involved in the deformation processes 102 focal mechanism of aftershocks have been computed from p wave polarities showing mainly pure reverse solutions we calculate the principal stress axes from a selected population of earthquakes providing a constraint on the stress regime of this part of the po plain the focal mechanisms are consistent with a n s subhorizontal 1 all the seismological data we have analysed confirm that this region is undergoing active compressional tectonics as already inferred from recent earthquakes geomorphological data and other stress indicators moreover the elongation of the reggio emilia aftershock sequence is consistent with the regional direction of the thrust fronts cropping out in the area suggesting that they are still active

fluvial system response to middle and upper pleistocene climate change in the meurthe and moselle valleys eastern paris basin and rhenish massif abstract research in the meurthe and moselle valleys downstream from the vosges massif has resulted in the definition of the terrace system and in the recognition of the climatic influence on its formation eight alluvial terraces were recognized at less than 100 m relative height an absolute chronology was established for the youngest alluvial terraces based on infrared optically stimulated luminescence and radiocarbon dating this provides evidence that each terrace corresponds to a single glacial interglacial cycle this result is confirmed by the study of numerous sections which present a constant succession of lithofacies in each valley part four alluvial sequences were also defined along the meurthe and moselle valleys reflecting middle and late pleistocene climate change their upper basin developed in the vosges massif was actually covered by glaciers during the pleistocene cold periods the differences between these four alluvial sequences are attributed to the unequal expansion of ice in the upper basins of the meurthe and moselle rivers and their tributaries in spite of these differences the sequences show important similarities main aggradation events correlate with cold periods pleniglacial and lateglacial whereas erosional phases occurred at the warm to cold transitions and secondarily at the pleniglacial lateglacial transitions this evolution is comparable with those already described in other northwestern european valleys especially since the upper saalian

when did the northern apennine become a mountain chain abstract the purpose of the present paper is to bracket the age of the initial uplift of the northern apennine chain by means of all the available evidence the collected data show that the age of the lacustrine or fluvio lacustrine units which have aggraded in the intramontane basins is late pliocene in the northwestern tip of the northern apennine and mostly early pleistocene elsewhere the age of the oldest terraced fluvial deposits showing the initiation of incision is mostly middle pleistocene the uplift of the summit areas of low relief most likely took place during the middle pleistocene it is concluded that the uplift occurring during middle and upper pleistocene caused an area of rather low relief to become the northern apennine mountain chain an eastward shift of the uplift through time is likely

the italian cmt dataset from 1977 to the present abstract the ingv harvard european mediterranean regional centroid moment tensor rcmt catalog collects solutions routinely computed since 1997 for earthquakes with moderate magnitude 4 5 m 5 5 in the mediterranean region the database represents an extension to smaller magnitudes of the harvard global cmt catalog based on analysis of seismograms recorded at regional distance and modeling of intermediate period surface waves the catalog includes about 600 events 200 of which in the italian region this study extends the catalog back in time for the italian region as long as made possible by available digital data i e since 1977 with the same analysis and inversion method used for current seismicity as a result we present here 65 new moment tensors for years between 1977 and 1997 these solutions represent 45 of the total number of events analyzed the existing seismograms being often too scarce to allow a stable solution the new dataset includes events in many seismic zones where moderate seismicity had previously been scarcely documented e g the po plain the central to southern apennines and the adriatic sea the complete dataset including previously determined rcmts and cmts represents the seismic deformation in the italian area during the last 25 years

palaeoecology of three interstadial events during oxygen isotope stages 3 and 4 a lacustrine record from lago grande di monticchio southern italy abstract three interstadial events recorded in a pollen diagram from lago grande di monticchio southern italy 40 56 40 n 15 36 e can be correlated with dansgaard oeschger events 12 14 and 20 of the grip summit greenland ice core based on a chronology of varve counts the events are dated respectively to the intervals 37 600 40 000 43 600 50 000 and 72 000 74 600 calendar yr bp the interstadials are of unequal duration the longest occupying 6400 years they appear to begin and end abruptly each is characterised by a sequence of pollen changes in the mesic forest component similarities in these sequences of mesic forest trees imply similar patterns of climatic change within each interstadial the sequences resemble that of the late glacial interstadial at monticchio although tree pollen abundance values reach as much as 60 during the interstadials there is always a substantial proportion of herb pollen tree growth may have been constrained by low co2 levels during the glacial phase of the last glacial interglacial cycle this record illustrates the potential of long continental records to present opportunities for detailed ecological and chronological analyses of sub interglacial warming events during oxygen isotope stages 3 and 4

fission track reconstruction of the front of the northern apennine thrust wedge and overlying ligurian unit in the northern apennines foreland the marnoso arenacea formation ma fm records post depositional burial temperatures overlapping with those of the zone of partial annealing of apatite fission tracks because the stratigraphy sedimentology petrography and structural evolution of this turbidite succession has been intensively studied over the last 40 years the ma fm provides an ideal case to apply the apatite fission track method the data show a general decrease of the maximum paleotemperature undergone by the ma samples toward the foreland area the maximum burial calculated using a geothermal gradient of 20 c km spans from more than 5 km to less than 2 5 km and indicates that the reconstructed total thickness of the ma succession is not enough to justify the determined burial values stratigraphic data indicates that the missing section consisted of a lower component foredeep successions and an upper allocthonous component composed of disrupted and chaotic oceanic sediments and minor ophiolites ligurian unit the ligurian unit overrode the foredeep succession during deposition its advancement toward the foreland area was associated with subsidence and only locally contrasted by thrust growth the reconstructed wedge shape of the ligurian unit in its final and pre erosional configuration at time of the maximum bunal of the ma succession shows a flat upper surface which corresponds to a paleosurface of early pliocene age this surface marks at 4 to 5 ma the onset of the exhumation phase which occurred at a mean rate of 1 2 mm yr

drainage basin responses to climate change recent investigations have shown that the extent of the channel network in some drainage basins is controlled by a threshold for overland flow erosion the sensitivity of such basins to climate change is analyzed using a physically based model of drainage basin evolution the golem model simulates basin evolution under the action of weathering processes hillslope transport and fluvial bedrock erosion and sediment transport results from perturbation analyses reveal that the nature and timescale of basin response depends on the direction of change an increase in runoff intensity or a decrease in vegetation cover will lead to a rapid expansion of the channel network with the resulting increase in sediment supply initially generating aggradation along the main network followed by downcutting as the sediment supply tapers off by contrast a decrease in runoff intensity or an increase in the erosion threshold will lead to a retraction of the active channel network and a much more gradual geomorphic response cyclic changes in runoff intensity are shown to produce aggradational degradational cycles that resemble those observed in the field cyclic variations in runoff also lead to highly punctuated denudation rates with denudation concentrated during periods of increasing runoff intensity and or decreasing vegetation cover the sediment yield from threshold dominated basins may therefore exhibit significant variability in response to relatively subtle environmental changes a finding which underscores the need for caution in interpreting modern sediment yield data

simulating internal and external controls on fluvial terrace stratigraphy a qualitative comparison with the maas record palaeohydrological studies indicate that the use of sedimentary palaeoclimatic indicators in fluvial sediments still requires rigorous calibration of the climatic controls on the formation of those indicators an explorative attempt is made using a simulation experiment with the fluver2 model the simulation illustrates that climate control on the erosion sedimentation behaviour of a large fluvial system differs along the fluvial system while in the uplifting hinterland only glacial extremes are recorded as sediments with a relatively limited preservation chance as terraces due to the uplift the more downstream reach towards the hinge zone displays a sensitive fluvial record registering even stadial interstadial dynamics well preserved in an extensive glacial interglacial terrace staircase downstream in a subsiding basin the most complete sedimentary record is preserved which still contains temporal gaps of approximately 20 related to the spatial delay effects of the external control of climate and related base level change a systematic comparison of simulated climate changes and resulting fluvial dynamics illustrates that due to the internal control of fluvial systems a one to one correlation between recorded fluvial dynamics and climate change becomes less the further one moves downstream along the longitudinal profile a qualitative comparison of the simulation results with the maas record reveals an interesting match suggesting that the simulated system dynamics may well apply the maas system

long river profiles tectonism and eustasy a guide to interpreting fluvial terraces along three rivers at the mendocino triple junction northern california strath cut and fill terraces have formed in response to tectonic and eustatic processes detailed surveying and radiometric dating at multiple sites indicate that lower reaches of the rivers are dominated by the effects of oscillating sea level primarily aggradation and formation of fill terraces during sea level high stands alternating with deep incision during low stands a eustasy driven deposi tional wedge extends tens of kilometers upstream on all rivers tapering to zero thickness this distance is greater than expected from studies of the effects of check dams on much smaller streams elsewhere due in part to the large size of these rivers however the change in gradient is nearly identical to other base level rise studies the depositional gradient is about half that of the original channel middle to upper reaches of each fiver are dominated by the effects of long term uplift primarily lateral and vertical erosion and formation of steep unpaired strath terraces exposed only upstream of the depositional wedge vertical incision at a rate similar to that of uplift has occurred even during the present sea level high stand along rivers with highest uplift rates strath terraces have steeper gradients than the modem channel bed and do not merge with marine terraces at the river mouth consequently they cannot be used to determine altitudes of sea level high stands strath formation is a continuous process of response to long term uplift and its occurrence varies spatially along a river depending on stream power and hence position upstream strath terraces are found only along certain parts of a coastal stream upstream of the aggradational effects of oscillating sea level and far enough downstream that stream power is in excess of that needed to transport the prevailing sediment load for a given size fiver the greater the uplift rate the greater the rate of vertical incision and consequently the less the like lihood of strath terrace formation and preservation

tectonic implications of the gps velocity field in the northern adriatic region 1 continuous and episodic gps observations between 1991 and 2004 show that adria moves independently of both stable eurasia and nubia adria moves nne at 3 4 5 mm yr increasing from n to s relative to eurasia and may be fragmenting along the gargano dubrovnik seismic zone the observed 2 3 mm yr of n s adria eurasia convergence is taken up by contraction across a narrow 70 km zone in the eastern alps and concomitant extrusion of the alpine north pannonian unit the adria central dinarides boundary is a broader collisional zone with intense 1 1 5 mm yr shortening near shore and 2 mm yr spread across the dinarides the remaining 1 2 mm yr motion e of the alps and ne of the dinarides is absorbed by the inverted contracting pannonian basin leaving no significant deformation above 0 5 mm yr in the western and northern carpathians and european platform

late quaternary sedimentation lower colorado river gulf coastal plain of texas investigations in the lower colorado river valley gulf coastal plain of texas have resulted in the development of a spatially and temporally controlled history of changes in channel and flood plain erosional and depositional processes when combined with paleoclimatic and stratigraphic data from the upper colorado river drainage and the record of glacio eustasy in the gulf of mexico this study permits evaluation of the relative influence of different external controls on channel and flood plain behavior the development of alluvial landforms and the development of alluvial stratigraphic sequences late pleistocene and holocene alluvial deposits of the lower colorado river have been subdivided into allostratigraphic units with chronological control afforded by radiocarbon ages in the bedrock confined valley up to 10 m of late pleistocene 20 000 14 000 yr b p sediments referred to as the eagle lake alloformation ela underlie a terrace at 17 20 m above the present day channel deposition of the ela was followed by bedrock valley incision then deposition of a complex holocene valley fill referred to as the columbus bend alloformation cba columbus bend allomembers 1 and 2 cba 1 and cba 2 underlie a terrace at 12 14 m above the present day channel cba 1 was deposited 12 000 5 000 yr b p whereas cba 2 was deposited 5 000 1 000 yr b p columbus bend allomember 3 cba 3 consists of channel and flood plain deposits that represent the past 600 yr of activity allostratigraphic units within the lower colorado valley correlate with allostratigraphic units in major valley axes of the upper colorado drainage and with records of climatic and environmental change suggesting that alluvial deposits record basinwide responses to climatically controlled changes in discharge regimes and sediment supply basal unconformities for holocene valley fills however appear to be 1 000 2 000 yr younger in the upper colorado drainage than they are in the lower colorado valley this time transgressioe episode of bedrock valley cutting was initiated by climatically controlled reductions in sediment supply but conditioned by limits on rates of up stream propagation of incision through a large drainage basin by contrast unconformities within holocene valley fills document time parallel episodes of flood plain abandonment and soil formation but little additional bedrock valley cutting and indicate decreased flood magnitudes following shifts to drier climatic conditions flood plain morphology and sedimentary facies changed through time in response to changes in climate coupled with a protracted degradation of upland soil mantles which altered the rate at which precipitation was transferred to stream channels as runoff during the late pleistocene through middle holocene runoff was filtered through deep upland soils floods were for the most part less flashy and contained within channel perimeters and flood plains were constructed by lateral migration without significant vertical accretion hence the ela and cba 1 contain few vertical accretion facies exposure of bedrock surfaces during the late holocene resulted in increased flood stages deep overbank flooding and construction of flood plains by vertical accretion hence cba 2 and cba 3 contain thick vertical accretion facies allostratigraphic units and bounding unconformities persist through the bedrock confined valley to the quaternary alluvial plain but stratigraphic architecture changes substantially in the downstream direction as a result of the last glacio eustatic cycle on the alluvial plain late holocene cba 2 and modern cba 3 deposited contemporaneously with the present interglacial highstand onlap and bury the ela and cba 1 which were emplaced during the last full glacial lowstand and the transgression that followed

long term fluvial archives in nw france response of the seine and somme rivers to tectonic movements climatic variations and sea level changes the seine and the somme are the two main rivers flowing from northwestern france into the channel during the pleistocene cold stages both rivers were tributaries of the river manche which was exporting sediments into the central deeps of the channel the river seine has a very well developed terrace system recording incision that began at around 1 ma the same age is proposed for the beginning of the main incision in the somme valley on the basis of morphostratigraphy pedostratigraphy palaeontology palaeomagnetism and esr datings the uplift rate deduced from analysis of the seine and somme terrace systems is of 55 to 60 m ma since the end of the lower pleistocene the response of the two rivers to climatic variations uplift and sea level changes is complex and variable in the different parts of the river courses for example the evolution of the lower seine system is influenced by uplift and climate changes but dominated by sea level changes in the middle seine the system is beyond the impact of sea level variations and shows a very detailed response to climatic variations during the middle and upper pleistocene in a context of uplift the somme valley response appears to be more homogeneous especially in the middle valley where the terrace system shows a regular pattern in which incision occurs at the beginning of each glacial period against a general background of uplift nevertheless the lower somme valley and the palaeo somme in the channel area indicate some strong differences compared with the middle valley influence of sea level variations and probably differences in rates of tectonic uplift between the channel and the present continent the differences in the responses of the two river valleys during the pleistocene are related to differences in the size of the fluvial basins to the local tectonic characteristics to the geometry of the platform connected to the lower parts of the valleys and to the hydrodynamic characteristics of each river finally it is shown from these examples that the multidisciplinary study of pleistocene rivers is a very efficient tool for the investigation of neotectonic activity

fluvial networks of the iberian peninsula a chronological framework abstract knowledge of the evolution of spanish fluvial networks has improved during recent years as more river systems have been studied and more geochronological data has become available however the chronological framework is a major issue as the range of applications is limited by methodological constraints and spatial coverage is sparse integration of absolute dating methods with biostratigraphy and palaeomagnetism permits the recent evolution of these river systems to be reviewed the timing of incision from the late neogene to the present varies between the major iberian fluvial systems depending on the substrata and tectonic settings early pleistocene and older fluvial sequences in the core areas of the iberian peninsula provide a more extensive record of fluvial evolution and are better preserved than the terrace flights in the coastal lowlands middle pleistocene sequences are well developed in most of the major river systems in iberia particularly those of the tajo guadalquivir and aguas river and frequently represent the principal climatic cycles of that period although tectonic and sea level effects can also be seen for late pleistocene to holocene times the scheme becomes more complex our review suggests that each river system has responded differently to local and regional climate control glacial and periglacial processes in headwaters in high mountain areas glacio eustatic sea level changes and local and regional tectonic patterns

dating fluvial terraces with and profiles application to the wind river wyoming abstract fluvial strath terraces provide a record of river incision and the timing of climatic perturbations to the fluvial system dating depositional surfaces like terraces that are older than the range of 14 c however is difficult we employ a cosmogenic radionuclide crn profile technique that addresses a major problem of crn dating on such surfaces nuclide inheritance by measuring 10 be and 26 al profiles we constrain the exposure age and the mean crn inheritance for the deposit the crn profile also yields a self check on the assumptions underlying the method we report our attempts to date terraces along the wind river wy like many sequences of western north american fluvial terraces these are inferred to reflect oscillation between glacial and interglacial conditions in the headwaters previous dating of some of these terraces and the associated terraces and glacial deposits makes this a unique location to compare dating methods dates from five sites along the bull lake glacial correlative terrace wr 3 are 118 125 ka which agrees with dates on bull lake age moraines and independent age estimates on the terrace and is consistent with the model of terrace glacial relationship crn inheritance is significant and highly variable requiring it be considered despite the additional sampling complexity assuming all inheritance in wr 3 deposits arises during exhumation in the headwaters we obtain minimum mean rates of exhumation of 13 130 m my for the source rocks alternatively assuming the crns are inherited during clast transport the time of fluvial transport from source to terrace is 10 ka it increases downstream and is lower for sand than cobbles the crn ages for older terraces wr 7 300 ka and wr 15 510 ka are lower by 50 than previous estimates based on tephrochronology the most plausible explanation is eolian deflation of a once thicker loess cover on the terrace surfaces mean thicknesses of loess of 0 5 1 5 m are required to reconcile these concentrations of crn with the previous estimates of age difficulty in dating the older terraces emphasizes that geologic caution independent estimates of age and multiple sample sites should still be part of dating depositional surfaces with crns even when employing the inheritance correction technique

fire and alluvial chronology in yellowstone national park climatic and intrinsic controls on holocene geomorphic processes we employed a systemwide approach a large and robust set of radiocarbon ages and modern process analogs to interpret the holocene history of forest fire related sedimentation and overall alluvial activity in northeastern yellowstone national park debris flow and flood events following the 1988 fires provided facies models for interpreting the stratigraphic record of fire related sedimentation within valley side alluvial fans of soda butte creek fire related deposits make up approximately 30 of the late holocene fan alluvium fifty 14 c ages on fire related events cluster within the intervals of 3300 2900 2600 2400 2200 1800 and 1400 800 yr b p and suggest earlier episodes of large fires and fan aggradation around 7500 5500 and 4600 4000 yr b p a major pulse of fire related debris flow activity between 950 and 800 yr b p coincided with the height of the widely recognized medieval warm period ca a d 1050 1200 instrumental climate records over the last 100 yr in yellowstone imply that the intensity and interannual variability of summer precipitation are greater during warmer periods enhancing the potential for severe short term drought major forest fires and storm generated fan deposition along lower soda butte creek fill cut terrace treads were created by lateral migration of channels and accumulation of overbank sediments ca 8000 yr b p terrace level t1a 7000 5600 t1b 3100 2600 t2 2000 1300 t3 and post 800 yr b p t4 these periods coincide with overbank sedimentation on slough creek and the lamar river but alternate with intervals of fire related fan deposition implying a strong climatic control local paleoclimatic data suggest cooler effectively wetter conditions during terrace tread formation in warmer drier intervals reduced average runoff in axial streams results in meander belt narrowing concurrent channel incision may be caused by infrequent large floods greater resistance to downcutting however allowed fewer terraces to be formed along slough creek and the lamar river alluvial systems in northeastern yellowstone show a clear response to millennial scale climatic cycles wherein alluvial fans aggrade and prograde over flood plains in drier periods axial streams widen their flood plains and trim back the fans during wetter periods small scale climatic fluctuations of the holocene thus had substantial impact on postglacial landscapes in northeastern yellowstone

morpho structural evolution of the valley slope systems and related implications on slope scale gravitational processes new results from the mt genzana case history central apennines italy abstract this work is aimed at constraining a slope scale deep seated gravitational slope deformation dsgsd and an associated rockslide avalanche in the frame of the quaternary morpho structural evolution of central apennines italy the study area is the western slope of the mt genzana calcareous ridge for which a conceptual slope evolutionary model had been already proposed the existing model has highlighted the role of inherited geological structural setting combined with quaternary morpho evolution in the onset of rock slope deformational processes until paroxysmal phases i e occurrence of massive rock slope failures in this work the previous conceptual evolutionary model was strengthened and detailed by means of a mid term landscape evolution model based on the study of geomorphic markers hanging at different elevations above the present valley floor the quaternary landscape evolution was also constrained by means of time dependent landscape metrics consequently it was possible to back analyse the observed dsgsd process from its onset up to the occurrence of localized massive rock slope failures through a time dependent stress strain numerical modeling the results of such a multi modeling approach i highlighted the importance of rock mass creep during some stages of the morpho evolution ii pointed out the relevant role of the inherited structural pattern in identifying the preferential strain concentration zones and failure surfaces and iii confirmed the hypothesis that the scanno rockslide avalanche scar is the result of two separate failure events as an initial landslide involving the lower part of the slope that favoured a subsequent failure in the upper part of the slope

gravity tectonics driven by quaternary uplift in the northern apennines insights from the la spezia reggio emilia geo transect abstract the neotectonics of the northern apennines is illustrated using a crustal scale geoseismic cross section based on seismic profiles and field mapping the geological profile crosses a variety of tectonic settings from the val di vara and val magra vv vm grabens in the inner side of the apennines to the pede apennine thrust fronts ptf and finally to the external fronts of the apennines both the vv vm extensional system and the ptf show evidence of early pleistocene tectonic activity whereas thrusting in the external apennine ended by late pliocene the sole decollement of the external thrusts cuts down westwards into the basement to a depth of about 15 km whereas the ptf joins a shallower detachment surface that follows the top of the basement this basal surface also represents the basal detachment of the vv vm extensional system with the vv vm and ptf defining a large scale gravitational spreading system we hypothesise that the regional quaternary uplift that affected the internal sector of the apennines promoted a gravitational spreading in the upper part of the orogenic wedge accounting for the coeval extension in the vv vm and shortening at the ptf and applicable to a 100 km long sector of the northern apennines

knickzone propagation in the black hills and northern high plains a different perspective on the late cenozoic exhumation of the laramide rocky mountains geomorphic research in the black hills and northern high plains poses an intriguing hypothesis for the cenozoic evolution of this salient of the laramide rockies most recently geologists have appealed to late cenozoic epeirogenic uplift or climate change to explain the post laramide unroofing of the rockies on the basis of field mapping and the interpretation of long valley profiles we conclude that the propagation of knickzones is the primary mechanism for exhumation in the black hills long profiles of major drainages show discrete breaks in the slope of the channel gradient that are not coincident with changes in rock type we use the term knickzones to describe these features because their profiles are broadly convex over tens of kilometers at and below the knickzone the channel is incising into bedrock abandoning a flood plain and forming a terrace above the knickzone the channel is much less incised resulting in a broad valley bottom numerous examples of stream piracy are documented and in each case the capture is recorded in the same terrace level these observations are consistent with migrating knickzones that have swept through black hills streams rearranging drainages in their wake we demonstrate there are two knickzone fronts associated with mapped terraces preliminary field evidence of soil development shows that these terraces are time transgressive in nature our data strongly suggest that knickzone propagation must be considered a viable mechanism driving late cenozoic fluvial incision and exhumation of the northern high plains and adjacent northern rocky mountains

extension controls quaternary tectonics geomorphology and sedimentation of the n appennies foothills and adjacent po plain italy abstract in the middle pleistocene thrusting in the n apennine fold and thrust belt came to an end and foredeep sedimentation in the adjacent po plain basin ceased a new tectono sedimentary regime was installed extensional faults were activated in the foothills and are limited to the northeast by a major sw dipping normal fault the bologna fault for which a vertical displacement of 1000 m is estimated the region northeast of the fault i e its footwall was progressively tilted towards the po plain the sw sectors of the tilting region were progressively uplifted above sea level subjected to erosion thereby feeding a deltaic system which prograded towards the northeast in the subsiding regions compressional structures without major deformation are recorded in the zone of maximum curvature all these features are explained by the onset of extensional deformation along the bologna fault and consequent flexural unloading of its footwall the evidence therefore shows that the transition region between the n apennine foothills and po plain has been under a tensional stress regime since the middle pleistocene

a soil chronosequence study of the reno valley italy insights into the relative role of climate versus anthropogenic forcing on hillslope processes during the mid holocene abstract relatively few soil chronosequences with good age control exist for late pleistocene and holocene deposits in the mediterranean region of europe yet surface soils and their young buried counterparts can provide meaningful information about the timing and processes of landscape response to external forcing such as climate or anthropogenic change here we present the results of a study that examines a well dated chronosequence of nineteen soil exposures in surficial deposits ranging in age from hundreds of years to hundreds of thousands of years located in the reno river valley near bologna italy the soil forming climate of the reno valley sits on a threshold between that which facilitates the accumulation of caco 3 and that which facilitates the translocation and formation of clay minerals and iron oxides once formed secondary iron oxides are relatively immobile in oxidizing conditions in the soil profile and therefore consistently record age trends with feo fed ratios decreasing predictably with soil age for all soils in the chronosequence the morphology of secondary carbonate accumulation and its depth of leaching also vary predictably with soil age but only for soils younger than about 12 000 years in these young soils horizons that contain secondary carbonate progress from relatively shallow stage i bk horizons in late holocene aged soils to deeper stage iii bk horizons in latest pleistocene aged soils in soils older than approximately 12 000 cal ybp however carbonate dissolution during wetter climates and the addition of colluvium and or dust to terrace surfaces become important factors in the preservation of carbonate in the profile and carbonate content is not predictable by age alone without significant depositional additions these older soils become decalcified pedogenic carbonate precipitated during drier climates is susceptible to dissolution during wetter periods as evidenced by discontinuous carbonate coatings on grains in some soils therefore overall measurable pedogenic carbonate content is spatially and temporally variable as a function of input of fresh carbonate and locally controlled soil moisture conditions particle size does not decrease predictably with soil age for reno valley soils and appears to be strongly influenced by parent material variability in younger soils and by dust additions in older soils our detailed examination of soil stratigraphy in the reno valley revealed evidence of significant aggradation of colluvium and tributary fans in the middle holocene between 6000 and 4000 ybp this aggradation pre dates bronze age agricultural expansion and appears to be instead attributable to the climate conditions of the middle holocene that have been documented elsewhere in italy for this time period this study demonstrates that late pleistocene and holocene surface soils in the mediterranean region of europe can effectively help elucidate rates and processes of landscape evolution

stochastic parameterization of convective area fractions with a multicloud model inferred from observational data abstractobservational data of rainfall from a rain radar in darwin australia are combined with data defining the large scale dynamic and thermodynamic state of the atmosphere around darwin to develop a multicloud model based on a stochastic method using conditional markov chains the authors assign the radar data to clear sky moderate congestus strong congestus deep convective or stratiform clouds and estimate transition probabilities used by markov chains that switch between the cloud types and yield cloud type area fractions cross correlation analysis shows that the mean vertical velocity is an important indicator of deep convection further it is shown that if conditioned on the mean vertical velocity the markov chains produce fractions comparable to the observations the stochastic nature of the approach turns out to be essential for the correct production of area fractions the stochastic multicloud model can easily be coupled to existing moist convection parameterization schemes used in ge

process based modelling of fluvial system response to rapid climate change ii application to the river maas the netherlands during the last glacial interglacial transition a comprehensive process based numerical model of catchment hydrology and alluvial channel dynamics is applied to the evolution of the river maas during the last glacial interglacial transition palaeo climatological reconstructions based on a number of climatic and environmental proxies are combined with atmospheric circulation model predictions to yield continuous time series for temperature precipitation and vegetation cover for the period of 14 9 c 14 kyr bp these climatic data are used as input for the numerical model predictions are made for discharge statistics hillslope erosion potential river channel sediment transport channel pattern and incision potential these predictions are compared with reconstructed fluvial dynamics of the maas during this time period we find that the major fluvial morphodynamical events can be explained by our model as a result of climate change induced affects however relatively high precipitation amounts during gs 1 must be applied in order to correctly predict floodplain wide incision during this period we further show by means of a number of sensitivity analyses that the uncertainty in the adopted climate reconstructions do not have a large impact on modelled morphodynamics c 2003 elsevier science ltd all rights reserved

human impact in the holocene fluvial and coastal evolution of the marche region central italy abstract today the coasts of the marche region are represented by almost continuous rectilinea sand beaches except in the north at the border with the romagna region and in the central part around the conero ridge where there are active rock cliffs the sandy coasts are protected almost everywhere by artificial barriers built up as a protection against the general tendency to retreat along some tracts the coastal erosion started at the beginning of this century but became generalized after 1940 1950 this was mainly due first to the reduction in sediment supply following the improvement in agricultural techniques after the italian unification and later to the widespread extraction of gravels from the thalwegs related to the rapid increase in urban population in the 1950s however in the same period along the rivers there was a widespread creation of artificial levees to prevent lateral erosion or flooding and to extend areas suitable for agriculture following these practices the lower middle tracts of the rivers underwent a strong vertical downcutting which increased as a result of the creation of checkdams downvalley of many bridges which contributed to the store of the sediments in the upper part of the valleys at present most of the rivers have an irregular course and are deeply entrenched in the bedrock or inside their own sediments up to the beginning of the century most of the lower tracts of the valleys were characterized by strong aggradation in a braidplain system this aggradation started as early as the middle ages 1100 ad but increased after the renaissance as a consequence of a generalized deforestation of the periadriatic basin and the following severe soil erosion in the mean time the coast underwent a very fast progradation in some places more than 500 m small deltas were created at the mouths of the rivers and longshore bars and sandy beaches began to occupy the base of the active cliffs which previously extended between one river and another however in the mountain parts of the river basins a meander course existed and in many cases still exists expecially where the human interventions were of limited extent before 1000 1100 ad all the rivers had a meander pattern and at the junction with the sea entered lagoons and swamps in most cases protected by littoral barrier beaches these conditions were established earlier than the third century bc and have been attributed to the first systematic land clearance and the following soil erosion during the bronze and iron ages at that time the regional coastline became almost rectilinear but with many active cliffs between one river and another before being affected by a major human impact earlier than 4000 years bp the natural coastal environment was represented by active rock cliffs which alternated with pocket beaches corresponding to a river mouth in some rivers embayments and beaches were located up to 4 5 km inland from the present day position after the flandrian transgression the evidence presented reveals major changes that can be attributed to human impact

fault plane solutions and seismicity of the italian peninsula abstract a new fault plane solution map of the italian peninsula is presented in this paper the earthquakes analyzed are included in the period 1905 1980 with magnitudes ranging 4 7 75 earthquakes are located in the crust while 31 are related to the deep and intermediate zone of the calabrian arc the large seismic events of the italian peninsula are generally associated with normal faulting while strike slip motion is mostly related to small earthquakes located along lateral segments of the mountain chain the deep and intermediate earthquakes of the tyrrhenian sea indicate predominant down dip compression and strike slip motion at the boundaries of this benioff zone this last is interpreted as a remnant of a subduction zone active since oligocene extending to 500 km depth with a very small lateral size about 300 km the present tectonics of this benioff zone is strongly conditioned by the lateral bending more so than the gravitational sinking process the coexistence of thrust and normal faulting motion associated to the earthquakes within a few tens of kilometers of each other seems to be explained by the strong lateral inhomogeneities of the crustal rocks present in this region more so than to the depth of the seismogenetic zone and the nature of the faulting process

late pleistocene channel incisions in the southern eel river basin northern california implications for tectonic vs eustatic influences on shelf sedimentation patterns abstract high resolution multichannel seismic mcs profiles from the southern offshore eel river basin off northern california show multiple superimposed buried channels beneath the continental shelf these channels display consistent southwest orientations their dendritic map pattern and low but consistent cross shelf gradients suggest that they formed by fluvial erosion during periods of shelf exposure associated with relative sea level lowstands all of the channels were incised after 500 ka the age of the onshore offshore hookton datum their frequency of incision exceeds that of known glacioeustatic lowstands since 500 ka confirming that some of the surfaces must have formed during relative lowstands initiated by local tectonic uplift sedimentation patterns in the eel river basin shift dramatically in response to relative sea level fluctuations today sediments from the eel river move north and west on the shelf in response mainly to large winter storm events in contrast fluvial incision on the exposed shelf during relative lowstands directed sediments to the southwest most likely into the head of the eel canyon shelf channels were probably fed not only by ancestral rivers but also by local uplifts like the table bluff anticline increases in gradient and channel depths at the southern end of the mcs coverage indicate that canyon forming processes modified fluvial channels as they converge towards embayments near the head of the eel canyon cyclic recurrence and consistent orientation of these channels demonstrate that the eel canyon has been extant through numerous relative sea level cycles and is perhaps as old as 500 ka

holocene strath terraces climate change and active tectonics the clearwater river basin olympic peninsula washington state the 400 km 2 clearwater river basin located on the pacific flank of the actively uplifting olympic mountains of western washington state contains a well preserved flight of holocene fluvial terraces we have collected a large data set of numeric ages from these terraces that is used to elucidate the geomorphic fluvial active tectonic and climatic processes that operate at holocene spatial and temporal scales detailed field mapping reveals three prominent holocene straths and their overlying terrace deposits terrace ages fall into three broad ranges ca 9000 11 000 yr b p qt4 4000 8000 yr b p qt5 and 0 3000 yr b p qt6 terrace deposit stratigraphy sedimentology and age distributions allow us to consider two alternative models for their genesis the favored model states that the terrace ages are coincident with lateral incision of the clearwater channel emplacement of the terrace alluvium and the carving of the straths vertical incision of the clearwater channel was primarily relegated to the brief 1000 yr intervals when we have no record of terraces alternatively the straths were carved as the channel incised vertically during the brief time periods between dated terrace deposits and the terrace ages record a subsequent long time of alluviation atop the straths and concomitant termination of vertical incision in both models we envision a clearwater river channel at or near capacity with a temporally variable rate of both lateral and vertical incision small deviations from this at capacity condition are driven by variations in the liberation and delivery of hillslope sediment to the channel we consider several causes for variable hillslope sediment flux in this tectonically active setting including holocene climate change and ground accelerations related to earthquakes holocene rates of vertical incision are reconstructed along nearly the entire clearwater valley from the wide distribution of dated terraces incision rates clearly increase upstream mimicking a pattern documented for pleistocene terraces in the same basin however the rates are 2 3 times those determined for the pleistocene terraces the faster holocene incision rates may be interpreted in terms of an increase in the rates of rock uplift however we favor an alternative explanation in which the holocene rates represent a channel rapidly reacquiring its stable graded concavity following protracted periods of time in the pleistocene when it could not accomplish any vertical incision into tectonically uplifted bedrock because the channel was raised above the bedrock valley bottom by climatically induced alluviation these results illustrate how even in tectonically active settings representative rates of rock uplift inferred from studies of river incision should be integrated over at least one glacial interglacial cycle

use of speleologic data to evaluate holocene uplifting and tilting an example from the frasassi anticline northeastern apennines italy deep inside the frasassi cave complex in the foreland fold and thrust belt of the northeastern apennines central italy the remains of hundreds of eels anguilla anguilla are found scattered on the shores of phreatic lakes up to 5 m above the water table these sub fossil eels and the speleothemic calcite encrusting some of them offer the rare opportunity for radiocarbon dating leading to a geochronologic scale for the shorelines which record the lowering of the water table and the uplifting of the frasassi area through the holocene the lakes margins are contoured by white microcrystalline calcite rinds which also record the progressive lowering of the water table detailed surveying revealed that these rinds are no longer horizontal but slightly tilted toward ene thus these rinds record a recent history not only of uplifting but also of tectonic tilting of this region the results of our analyses indicate that the apennine area around frasassi has been rising for the past 8000 years at a mean rate of 0 6 mm yr which is consistent with uplifting rates estimated from the step topography arrangement of interglacial fluvial terraces for the whole quaternary period in this region this work demonstrates how an interdisciplinary approach to speleologic research can provide a significant contribution to active tectonic studies

interactions between mantle upwelling drainage evolution and active normal faulting an example from the central apennines italy summary in this paper we show that the processes that have shaped the quaternary surface development of the apennines in central italy are all consequences of a single subcrustal process the upwelling of the mantle the relationship between gravity and topography shows that mantle convection is responsible for a long wavelength 150 200 km topographic bulge over the central apennines and stratigraphic evidence suggests this bulge developed in the quaternary active normal faulting is localized at the crest of this bulge and produces internally draining fault bounded basins these basins have been progressively captured by the aggressive headward erosion of major streams that cut down to the sea on the flanks of the regional bulge the only surviving closed basins are those on the apennine watershed most distant from the marine base level where continued normal faulting is still able to provide local subsidence that defeats their capture by the regional drainage network understanding the competition between regional capture and local fault related subsidence of intermontane basins is crucial for recognizing potentially hazardous active faults in the landscape and also for interpreting the sediment supply to adjacent offshore regions central italy provides a good modern analogue for processes that are probably common in the geological record particularly on rifted margins and intracontinental rifts but may not have been fully appreciated

crustal velocity and strain rate fields in italy and surrounding regions new results from the analysis of permanent and non permanent gps networks summary we present a new geodetic velocity solution for italy and the surrounding areas obtained from an analysis of continuous and survey mode global positioning system observations collected between 1991 and 2002 we have combined local regional and global networks into a common reference frame velocity solution providing a new detailed picture of the regional scale deformation field in the central mediterranean our velocity estimates are computed with respect to a new stable eurasian reference frame constraining the kinematics of the greater african eurasian plate boundary system in the study area we provide strain rate values for the main seismotectonic districts which are in good agreement with the seismic deformation inferred from earthquake focal mechanisms the southern tyrrhenian area calabria the apennines the southeastern alps the southern dinarides and the albanides display deformation rates at the order of 20 30 nanostrain yr 1 the corsica sardinia block moves according to eurasian plate motions and there is no indication that the opening of the tyrrhenian is still active the pelagian and sicilian domains are separated by a northwest southeast discontinuity the sicily channel rifted area and marginally significant relative motion between the pelagian plateau and the african plate is also observed the southern tyrrhenian is affected by north south compression and accommodates up to 50 per cent of the africa eurasia relative plate motion whereas the calabrian arc exhibits 2 mm yr 1 northwest southeast extension the observed deformation pattern suggests the presence of a major approximately north south tectonic discontinuity separating the sicilian and calabrian domains an extensional boundary observed along peninsular italy coincides with the distribution of seismogenic faults along the axis of the apennines this boundary separates a tyrrhenian and an adriatic domain with diverging velocities orientated north nnw ward and northeastward respectively the apennines are extending perpendicularly to the chain axis at rates of less than 3 mm yr 1 and only in the outer northern apennines indications of active shortening are observed insignificant deformation is observed in the western po plain and the western alps while the central and eastern alps display north south shortening the eastern adriatic domain is shortening perpendicular to the dinaric front with strain rates increasing from north to south the locus of collision between the aegean balkan system and the adriatic and ionian domains is marked by the kephalonia fault system which accommodates up to 20 1 mm yr 1 of right lateral motion the deformation pattern observed in the peri adriatic domain is well described by a counter clockwise rotation of the adriatic microplate around a pole located in the western alps

multi phased uplift of the southern margin of the central anatolian plateau turkey a record of tectonic and upper mantle processes abstract uplifted neogene marine sediments and quaternary fluvial terraces in the mut basin southern turkey reveal a detailed history of surface uplift along the southern margin of the central anatolian plateau from the late miocene to the present new surface exposure ages 10be 26al and 21ne of gravels capping fluvial strath terraces located between 28 and 135 m above the goksu river in the mut basin yield ages ranging from ca 25 to 130 ka corresponding to an average incision rate of 0 52 to 0 67 mm yr published biostratigraphic data combined with new interpretations of the fossil assemblages from uplifted marine sediments reveal average uplift rates of 0 25 to 0 37 mm yr since late miocene time starting between 8 and 5 45 ma and 0 72 to 0 74 mm yr after 1 66 to 1 62 ma together with the terrace abandonment ages the data imply 0 6 to 0 7 mm yr uplift rates from 1 6 ma to the present the different post late miocene and post 1 6 ma uplift rates can imply increasing uplift rates through time or multi phased uplift with slow uplift or subsidence in between longitudinal profiles of rivers in the upper catchment of the mut and ermenek basins show no apparent lithologic or fault control on some knickpoints that occur at 1 2 to 1 5 km elevation implying a transient response to a change in uplift rates projections of graded upper relict channel segments to the modern outlet together with constraints from uplifted marine sediments show that a slower incision uplift rate of 0 1 to 0 2 mm yr preceded the 0 7 mm yr uplift rate the river morphology and profile projections therefore reflect multi phased uplift of the plateau margin rather than steadily increasing uplift rates multi phased uplift can be explained by lithospheric slab break off and possibly also the arrival of the eratosthenes seamount at the collision zone south of cyprus

fluvial incision and tectonic uplift across the himalayas of central nepal the pattern of fluvial incision across the himalayas of central nepal is estimated from the distribution of holocene and pleistocene terraces and from the geometry of modern channels along major rivers draining across the range the terraces provide good constraints on incision rates across the himalayan frontal folds sub himalaya or siwaliks hills where rivers are forced to cut down into rising anticlines and have abandoned numerous strath terraces farther north and upstream in the lesser himalaya prominent fill terraces were deposited probably during the late pleistocene and were subsequently incised the amount of bedrock incision beneath the fill deposits is generally small suggesting a slow rate of fluvial incision in the lesser himalaya the terrace record is lost in the high range where the rivers are cutting steep gorges to complement the terrace study fluvial incision was also estimated from the modern channel geometries using an estimate of the shear stress exerted by the flowing water at the bottom of the channel as a proxy for river incision rate this approach allows quantification of the effect of variations in channel slope width and discharge on the incision rate of a river the determination of incision rates requires an additional lithological calibration the two approaches are shown to yield consistent results when applied to the same reach or if incision profiles along nearby parallel reaches are compared in the sub himalaya river incision is rapid with values up to 10 15 mm yr it does not exceed a few millimeters per year in the lesser himalaya and rises abruptly at the front of the high range to reach values of 4 8 mm yr within a 50 km wide zone that coincides with the position of the highest himalayan peaks sediment yield derived from the measurement of suspended load in himalayan rivers suggests that fluvial incision drives hillslope denudation of the landscape at the scale of the whole range the observed pattern of erosion is found to closely mimic uplift as predicted by a mechanical model taking into account erosion and slip along the flat ramp flat geometry of the main himalayan thrust fault the morphology of the range reflects a dynamic equilibrium between present day tectonics and surface processes the sharp relief together with the high uplift rates in the higher himalaya reflects thrusting over the midcrustal ramp rather than the isostatic response to reincision of the tibetan plateau driven by late cenozoic climate change or late miocene reactivation of the main central thrust

compression along the northern apennines evidence from the mw 5 3 monghidoro earthquake in this paper we present the seismological data recorded during the deployment of a dense three component seismic network installed a few hours after the 2003 mw 5 3 monghidoro earthquake in northern apennines the main shock focal solutions derived from polarities distribution and body wave modelling of regional broadband data show a ne sw striking reverse mechanism accurate relative locations of aftershocks and the inversion of focal mechanisms show that earthquakes occurred on a nw dipping backthrust within the adria lithosphere under a nw trending horizontal compression the observed compression is a secondary process possibly explained by differential motion within the adriatic lithosphere fault geometry and kinematics is controlled by pre existing structures

a fluvial record of long term steady state uplift and erosion across the cascadia forearc high western washington state six late quaternary river terraces preserved along the clearwater river in northwestern washington state provide a 140 ka record of long term incision and uplift across the western side of the cascadia forearc high terrace ages are constrained by weathering rind and radiocarbon dating and by correlation to dated coastal glacio fluvial deposits and the global eustatic curve the terraces overlie flat bedrock surfaces called straths which represent uplifted segments of the river channel bedrock incision is measured by the height of a strath relative to the adjacent modern river channel the straths along the clearwater show an upstream increase in bedrock incision ranging from 0 at the coast to a maximum of 110 m in the headwaters the incision at any point along the profile increases systematically with strath age the calculated incision rates range from 10 ky the clearwater river valley has maintained a steady state profile defined by a long term balance in the rates of incision and rock uplift upstream divergence of terraces is best explained by an increase in the rate of rock uplift from the coast toward the central part of the range these results are consistent with other evidence indicating a long term steady state balance between the accretionary influx and the erosional outflux for this part of the cascadia subduction wedge since 14 ma these results help show how terrace deposits form in tectonically active landscapes the dominantly fluvial clearwater drainage was forming straths while alpine glaciers were advancing in adjacent drainages in turn the straths were buried during the transition to interglacial times because of increased sediment supply due to local deglaciation and because of eustatic highstands that forced aggradation in the lower reach of the drainage and across the continental shelf as well the fluvial system shows strong forcing by the glacial climate cycle even so the river appears to have returned to the same valley profile during each cycle of strath cutting thus bedrock incision is clearly unsteady at time scales shorter than the glacial climate cycle 100 ky but appears to be relatively steady when averaged over longer time scales a simple kinematic model is used to examine how uplift of the cl our analysis indicates that the accretionary flux into the wedge occurs mainly by frontal accretion and not by underplating if accretion occurred entirely at the front of the wedge the present west coast should be moving to the northeast at 3 m ky relative to a fixed puget sound this prediction is in good agreement with offset of a 122 ka sea cliff preserved at the southwest side of the clearwater valley profile in this case the long term margin perpendicular shortening would account for 20 to 35 percent of the geodetically measured northeast southwest shortening across the olympic mountains

geomorphic and tectonic process rates effects of measured time interval analysis of the original numerical components of diverse geomorphic and tectonic process rates indicates that process rate is not independent of measured time interval this implies that direct comparison of geologic process rates measured over variable time intervals may not be valid and that conclusions based on those comparisons regarding changes in rates through geologic time may be misleading in some cases calculation of statistically derived scaling functions is one approach that can be used to account for this measurement interval bias and to improve comparisons of geologic process rate data when this approach is used a 10 4 or 10 5 yr variation in the measured time interval accounts for approximately one order of magnitude change in the measured process rate the magnitude of the correction can substantially affect conclusions of studies that compare uncorrected process rates calculated from variable time intervals

heinrich events massive late pleistocene detritus layers of the north atlantic and their global climate imprint 1 millennial climate oscillations of the glacial interval are interrupted by extreme events the so called heinrich events of the north atlantic their near global footprint is a testament to coherent interactions among earth s atmosphere oceans and cryosphere on millennial timescales heinrich detritus appears to have been derived from the region around hudson strait it was deposited over approximately 500 250 years several mechanisms have been proposed for the origin of the layers binge purge cycle of the laurentide ice sheet jokulhlaup activity from a hudson bay lake and an ice shelf buildup collapse fed by hudson strait to determine the origin of the heinrich events i recommend 1 further studies of the timing and duration of the events 2 further sedimentology study near the hudson strait and 3 greater spatial and temporal resolution studies of the layers as well as their precursory intervals studies of previous glacial intervals may also provide important constraints

evolution of retreating subduction boundaries formed during continental collision retreating subduction boundaries formed where the rate of subduction exceeds the rate of overall plate convergence appear to be commonly developed features within regions of early or incomplete continent continent collision they are characterized by regional extension within the overriding plate and at their leading edge by thin skinned arcuate thrust belts that are concave towards the overriding plate as is illustrated by examples from the mediterranean region the formation of retreating subduction boundaries is intimately related to the process of continental collision during the early stages of collision retreating subduction boundaries are commonly formed by lateral ejection from zones of crustal shortening along the main collision boundary retreating plate boundaries can also form before the main collision and the associated thrust belts emplaced as precollisional accretionary assemblages because the driving mechanism for retreating subduction boundaries appears to be gravity acting on a dense subducted slab slab pull subduction usually ceases when and only when thick buoyant continental crust enters the subduction zone thus differences in the evolution and duration of retreating subduction systems can be largely attributed to the size and configuration of the deep water regions available to be subducted in some cases retreating subduction boundaries may escape into the open ocean where they form nearly isolated local tectonic systems in these systems the rate of subduction is approximately compensated by the rate of upper plate extension and migration of the system across the oceanic region may be very rapid for example the horseshoe seamounts located about 800 km offshore in the eastern north atlantic may be the active expression of an east dipping westwardly migrating retreating subduction boundary that has evolved from the betic cordillera rif system active in miocene time and may now be progressing across the atlantic at approximately 50 mm yr an analogous situation may be represented by the scotia arc system a westward dipping retreating subduction system located between the south american and antarctic plates which may have escaped into the south atlantic ocean from a zone of crustal shortening in the andes and is now progressing across the atlantic at a rate of about 80 mm yr

river terrace development by concurrent fluvial processes and climatic changes abstract along the usui river in central japan three well developed terrace levels are observed each terrace is subdivided into two segments a filltop terrace along the upper reach and a strath terrace along the lower one three valley fillings with coarse gravel beds in the upper reach correspond to the last three glacial ages the positions of these valleysfills migrated upstream from the older terrace to the younger one to clarify the response of fluvial systems to climatic change terrace sediments were interpreted from the viewpoint of paleohydraulics using the grain diameter of terrace sediments paleo tractive forces were evaluated based on the correlation between tractive force and grain diameter of the sediment on the present river bed the valley filling was caused by the diminution in tractive force related to the decrease in heavy rain produced by typhoons during the glacial ages during the interglacial ages the reverse responses occurred due to the increased incidence of typhoons from another aspect of the development of river landforms the decrease in the liver channel gradient during the interglacial ages caused the transportational and or depositional area of coarse gravels to migrate upstream in the subsequent glacial ages

short term vertical velocity field in the apennines italy revealed by geodetic levelling data we estimate current vertical movements along the apennines italy through repeatedly measured high precision levelling routes in order to highlight regional crustal deformation the analysis of a geodetic database with a minimum benchmark density of 0 7 bm km 1943 2003 time period is carried out we evaluate systematic and random error and their propagation along the levelling routes tests on original raw height data have been carried out to define error propagation the computed relative vertical rates stand significantly above error propagation a series of traverses along and across the apennines and a map of relative vertical velocities reveal a geodetic signal characterised by values up to 2 5 3 0 mm a and by wavelengths up to 100 km

late quaternary uplift and valley evolution in the northern apennines lamone catchment abstract the topographic evolution of mountain chains is fundamentally dictated by the balance of erosional and tectonic processes in the northern apennines several questions about the late holocene to present deformation style and uplift rates are still open we consider a typical ne facing drainage basin focusing on all the geomorphic markers capable of supplying direct or indirect information regarding tectonic forcing on the landscape characteristics of altitude and relief drainage pattern river profile and fluvial response expressions were found to be in good agreement indicating that the most recent tectonic activity consists of a general persistent uplift of the chain associated with an extensional regime where different sectors are distinguished through differential uplift such differences have been found to act both along and transverse to the chain causing similar coherent patterns of response in erosional processes the geomorphology of the catchment displays several features which together with the long sustained tectonic forcing indicate the near attainment of a dynamic equilibrium between the rates of tectonic forcing and erosional processes creating steady state topography

morphotectonic approach to the drainage analysis in the north marche region central italy abstract the umbro marchean apennines form an arcuate nw se fold and thrust belt of ne convexity the orogen developed from the early miocene and shortened the more than 5 km thick meso cenozoic stratigraphic succession by about 30 the internal part of the mountain chain is however overprinted by sw dipping extensional normal faults that bound the plio pleistocene continental basins nevertheless the distribution of river terraces all along the main river valleys clearly indicates that middle upper pleistocene and holocene vertical uplift dominated over local anticlinal uplift for the entire studied area the drainage network of the marche region in the external part of the umbro marchean apennines has an overall sub parallel pattern oriented mainly sw ne and transversely breaches the main calcareous anticlinal ridges before reaching the adriatic coast emergence and drainage initiation may have begun as early as the messinian cave systems formed during the erosion history and document former stream levels the breaching of the high amplitude anticlinal ridges was controlled mainly by joint systems and locally by nne ssw striking faults in turn both superimposition and stream piracy phenomena could have played a significant control in the drainage network development and in places complex mechanisms involving antecedence cannot be ruled out for streams bypassing anticlinal ridges

controls on the channel width of rivers implications for modeling fluvial incision of bedrock on the basis of the manning equation and basic mass conser vation principles we derive an expression for scaling the steady state width w of river channels as a function of discharge q channel slope s roughness n and width to depth ratio a w 5 a a1 2 2 3 3 8 q 3 8 s 23 16 n 3 8 we propose that channel width to depth ratio in addition to roughness is a function of the material in which the channel is developed and that where a river is con fined to a given material width to depth ratio and roughness can be assumed constant given these simplifications the expression emulates traditional width discharge relationships for rivers incis ing bedrock with uniformly concave fluvial long profiles more sig nificantly this relationship describes river width trends in terrain with spatially nonuniform rock uplift rates where conventional discharge based width scaling laws are inadequate we suggest that much of observed channel width variability in river channels confined by bedrock is a simple consequence of the tendency for water to flow faster in steeper reaches and therefore occupy smaller channel cross sections we demonstrate that using conventional scaling relationships for channel width can result in underestima tion of stream power variability in channels incising bedrock and that our model improves estimates of spatial patterns of bedrock incision rates

genetically related alluvial deposits across active fault zones an example of alluvial fan terrace correlation from the upper quaternary of the southern po basin italy integrated studies of alluvial fan systems and related intramontane valley deposits provide potentially useful tools for understanding the character of alluvial sedimentation and its control in fault controlled piedmont zones an example is reported from the uppermost quaternary alluvial deposits of the northern apennines and the southern margin of the po basin a distinctive cyclicity characterizes both the outcropping and the buried units in the study area in intramontane valleys individual cycles consist of regular alternations of sections displaying high and low terrace preservation in the subsurface a rhythmic alternation of coarse grained bodies and laterally extensive pelitic horizons occurs at various scales and represents the basic cyclic motif of the depositional system the correlation between the terrace sequences and the depositional cycles in the subsurface allows the differentiation of distinct sequences with a characteristic internal architecture in the lower part of sequences poorly preserved terrace deposits are laterally correlatable with alluvial fan gravel bodies whereas highly preserved terrace deposits are correlated laterally with predominantly floodplain sediments in the upper part of sequences reliable correlation lines have been constructed using 14c dating thrust tectonics and climate exerted a major control on sequence development deep valley excavation with subsequent low terrace preservation occurred in response to relief rejuvenation during successive thrusting events on the other hand decreasing erosion related to periods of minor tectonic activity led to terrace preservation in the intramontane valleys the coeval episodes of alluvial fan growth and abandonment recorded at the basin margin are interpreted to reflect changes in the efficiency of the drainage system due to variations of tectonic uplift in the adjacent areas alternating phases of deglaciation and renewed glaciation however are inferred to have played a major role in controlling the amount and type of sediment delivered to the alluvial fan complexes

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

thrust front segmentation induced by differential slab retreat in the apennines italy new seismic reflection data reveal that the south eastward prolongation of the apennine thrust front in the central adriatic sea is most likely located in a more external position with respect to the traditional interpretation in this new interpretation the apennine thrust front shows a segmented geometry in correspondence to the tremiti lithospheric transfer zone the available data suggest that the north eastward flexural retreat of the subducting adriatic lithosphere and the related frontal accretion of the apennine accretionary prism have acted during the last 5 ma and may be considered still lively in both the po plain and in the central adriatic domain north of the tremiti lineament by analysing the tectonic evolution of the apulo adriatic areas it may be argued that the differential slab retreat between the central and southern sectors of the subducting adriatic plate has been able to induce the segmentation of the apennine thrust front

fluvial terraces of the lower susquehanna river abstract fluvial terraces of the lower susquehanna river offer a unique opportunity to investigate the late stage geologic and geomorphic evolution of the u s atlantic passive margin petrography and elevation distinguish and provide a basis for correlation of two groups of terraces the upland terraces and lower terraces through the piedmont newark basin and great valley downstream correlation to dated upper coastal plain and fall zone fluvial deposits relative weathering and soil profile development characteristics establish terrace age upland terraces tg1 tg2 and tg3 middle to late miocene strath terraces 80 to 140 m above the present channel occur only along the piedmont reach they are underlain by unstratified texturally mature quartz dominated roundstone diamictons lower terraces qtg qt1 qt6 pliocene and pleistocene strath and thin aggradational terraces within 45 m of the present channel are underlain by stratified and unstratified texturally and compositionally immature sand gravel and pebbly silt terrace age and longitudinal profiles suggest complex interactions among relative base level long term flexural isostatic processes climate and river grade our model for terrace genesis requires the susquehanna river to attain and maintain a characteristics graded longitudinal profile over graded time for the u s atlantic margin we propose that straths are continually cut along this graded profile during periods of relative base level stability achieved by slow steady isostatic continental uplift acting in concert with eustatic rise change in an external modulating factor such as eustatic fall or climate change results in fluvial incision and subsequent genesis of strath terraces longitudinal profiles of lower susquehanna river terraces which converge at the river mouth diverge through the piedmont and reconverge north of the piedmont contrast with their hypothesized original concave up profiles progressive and cumulative flexural upwarping of the atlantic margin accounts for terrace profile deformation suggesting flexural isostasy as a first order regional deformation mechanism these results offer new interpretations of terrace age correlation and geologic significance that require modification of previous studies suggesting uplifted or anticlinically warped peneplains on the u s atlantic margin

a 900 k y record of strath terrace formation during glacial interglacial transitions in northwest china the timing of the development of strath terraces with respect to climatic variability remains equivocal previous studies attribute strath terrace formation to glacial or interglacial climates or to variations in sediment and water fluxes that cause lateral erosion followed by vertical incision a chronology of strath terrace formation spanning similar to900 k y has been generated on the basis of loess paleosol couplets and paleomagnetic thermoluminescence and radiocarbon dating of strath terraces in the qilian shan of northeastern tibet repetitive stratigraphic and geomorphic patterns on each terrace indicate that they formed during glacial interglacial transitions long term bedrock incision rates and inferred rock uplift rates appear steady and unrelated to strath formation over the past 900 k y

thresholds of strath genesis deduced from landscape response to stream piracy by pancho rico creek in the coast ranges of central california recent compelling arguments regarding the overwhelming influence of drainage basin lithology on strath formation montgomery 2004 require reevaluation of the role other factors play in this process pancho rico creek prc is a bedrock eroding stream in the tectonically active central coast ranges of california late quaternary time stream piracy of the upper san lorenzo creek catchment by prc caused instantaneous at graded timescales catchment area expansion from 99 5 156 6 km 2 and a significant change in the lithologic composition of prc channel bedload this naturally occurring experiment in the southern gabilan range provides insight regarding the influences of catchment area and channel bedload composition on formation of fluvial straths in the context of newly recognized controls on bedrock channel erosion sklar and dietrich 2001 stock and others 2005 distinct compositional differences in pre and post capture prc alluvium facilitates deducing from alluvial stratigraphy pre and post capture fluvial processes the pre capture drainage basin of prc known as pancho rico valley is entirely underlain by predominantly fine grained friable clastic marine sediments of the pancho rico formation pre capture prc alluvium consists only of pancho rico formation clasts but post capture prc alluvium also includes relatively competent clasts of franciscan complex rocks pre and post capture straths formed in pancho rico valley only along reaches of prc where drainage area was is greater than ca 60 km 2 this indicates that a minimum catchment area is necessary for prc to carve straths spatial and temporal patterns of strath formation in pancho rico valley support the hypothesis that distribution of straths within a drainage basin underlain by mechanically weak rock is largely dependent on catchment area two hypotheses are proposed to explain differences in the character of pre and post capture straths as well as the processes leading to their formation and or preservation pre capture straths are paired major straths which indicate that lateral incision prevailed over vertical incision during a given interval of graded time for example bull 1990 post capture straths are unpaired minor straths which indicate simultaneous vertical and lateral incision during a given interval of graded time for example bull 1990 one hypothesis proposes that prc was able to simultaneously over graded timescales lower and widen its channel in post capture time because the presence of relatively competent bedload enhanced abrasion and accelerated channel denudation relatively incompetent bedload precluded simultaneous channel lowering and widening in pre capture time an alternative favored hypothesis is that post capture minor straths are present along prc because they are buried under franciscan complex derived gravelly alluvium which is more resistant to weathering than pancho rico formation derived gravelly alluvium thin deposits typical of minor erosional straths and composed of readily weathered pancho rico formation bedload were insufficient to protect straths from weathering and erosion in pre capture time pre capture straths survived only when buried by substantial amounts of alluvium as may have occurred during an episode of strath formation and alluviation caused by climate change

numerical modeling of fluvial strath terrace formation in response to oscillating climate many river systems in western north america retain a fluvial strath terrace rec ord of discontinuous downcutting into bedrock through the quaternary their importance lies in their use to interpret climatic events in the headwaters and to determine long term incision rates terrace formation has been ascribed to changes in sediment supply and or water discharge produced by late quaternary climatic fluctuations we use a one dimensional channel evolution model to explore whether temporal variations in sediment and water discharge can generate terrace sequences the model includes sediment transport vertical bedrock erosion limited by alluvial cover and lateral valley wall erosion we set limits on our modeling by using data collected from the terraced wind river basin two types of experiments were performed constant period sinusoidal input histories and variable period inputs scaled by the marine 18 o rec ord our simulations indicate that strath terrace formation requires input variability that produces a changing ratio of vertical to lateral erosion rates straths are cut when the channel floor is protected from erosion by sediment and are abandoned and terraces formed when incision can resume following sediment cover thinning high sediment supply promotes wide valley floors that are abandoned as sediment supply decreases in contrast wide valleys are promoted by low effective water discharge and are abandoned as discharge increases widening of the valley floors that become terraces occurs over many thousands of years the transition from valley widening to downcutting and terrace creation occurs in response to subtle input changes affecting local divergence of sediment transport capacity formation of terraces lags by several thousand years the input changes that cause their formation our results suggest that use of terrace ages to set limits on the timing of a specific event must be done with the knowledge that the system can take thousands of years to respond to a perturbation the incision rate calculated in the field from the lowest terrace in these systems will likely be higher than the rate calculated by using older terraces because the most recent fluvial response in the field is commonly downcutting associated with declining sediment input since the last glacial maximum this apparent increase in incision rates is observed in many river systems and should not necessarily be interpreted as a response to an increase in rock uplift rate

geomorphic evidence for an emergent active thrust along the edge of the po plain the broni stradella fault 1 we present here geomorphic evidence for an emergent active thrust along the northwestern apennine front about 50 km south of milano fieldwork combined with spot image analysis attests to the presence of a 35 km long en echelon cumulative fault scarp that cuts e w across quaternary surface deposits from casteggio to sarmato the scarp offsets vertically alluvial fans and terraces emplaced by tributaries of the po river that flow northward from the apennines incision by such tributaries occurs only south of the scarp valleys of smaller streams stand in hanging position to the northeast the buried east dipping pavia lateral ramp bounds the san colombano anticline we interpret the montebello sarmato scarp to result from the emergence of an active thrust fault dipping south the stradella thrust which splays eastward from that ramp total station profiles leveled perpendicular to the stradella thrust show variable cumulative surface throws ranging from 2 to 25 m scarp degradation analysis indicates fairly recent offset of the terrace surfaces 10 100 kyr suggesting a minimum uplift rate of 0 3 mm yr the underlying fault might thus be one of the most active thrust ramps along this segment of the apennines n s to n15 w shortening is consistent with both the e w strike of this thrust ramp and with coeval oblique sinistral motion on the nne ssw trending pavia lateral ramp the vogherese bobbiese earthquake of 1828 i ix south of casteggio and broni may have activated one segment of this lateral ramp rather than the stradella thrust other historical events i 7 that caused damage in pavia piacenza lodi and milano in the last 2000 years 290 a d 1249 a d 1276 a d 1473 a d may have occurred on the broni stradella thrust or on the blind san colombano and lodi thrusts farther north this makes detailed paleoseismological studies and trenching across its trace mandatory

the crustal structure of the northern apennines central italy an insight by the crop03 seismic line in this paper the crop03 deep seismic reflection profile in the northern apennines is described and re considered in light of new geophysical data and interpretations made available in the last five years particularly from heat flow measurements aeromagnetics tomography active stress determination and passive seismology the crustal structure of the northern apennines is shown to be composed of two distinct domains to the west is the tyrrhenian domain and to the east is the adriatic domain these domains have distinctive geological and geophysical characteristics that exhibit distinct reflectivity patterns at all crustal levels in the tyrrhenian domain the upper oligocene lower miocene compressive structures are no longer recognizable because they are dissected by subsequent extensional tectonic features the seismic profile highlights the strong asymmetry of extensional deformation and the upper crust is affected by a set of six major east dipping low angle normal faults in the adriatic domain compressive tectonics have acted since the middle miocene and the pattern of shallow contractional structures is well preserved the geological interpretation of the seismic data supports a thick skinned style of deformation where the basement is involved in the major thrust sheets the good quality of seismic data also allows for determining the total shortening produced by the contractional structures in the central part of the profile at the border between the tyrrhenian and adriatic domains seismic data shows the presence of an intermediate sector the sector consists of a highly reflective window where the refraction data indicate a local doubling of the crust for about 30 km a scenario is presented that attempts to describe the geodynamics that drove the tectonic evolution of the northern apennines since the upper oligocene

dynamic equilibrium among erosion river incision and coastal uplift in the northern and central apennines italy erosion river incision and uplift rates in the northern and central apennines italy since 0 9 ma are determined from new cosmogenic nuclide data beryllium 10 concentrations in modern and middle pleistocene sediments indicate erosion rates from 0 20 to 0 58 mm yr these rates are similar to estimates of sediment yield 0 12 0 44 mm yr river incision 0 35 mm yr and uplift 0 01 1 0 mm yr rates inferred from other methods that integrate landscape process rates since the early pleistocene these rates of landscape change are significantly lower than long term exhumation rates of 1 2 mm yr since ca 4 5 ma inferred from thermochronometry collectively these data suggest that hillslope erosion and river incision rates in the northern and central apennines have balanced local uplift rates for 1 my but that exhumation rates have slowed significantly since emergence of the mountain chain in the pliocene this condition of dynamic equilibrium was potentially achieved within ca 3 ma similar to some model predictions of hillslope and fluvial system adjustment

a signature of transience in bedrock river incision rates over timescales of 10 4 10 7 years measured rates of river incision into bedrock are commonly interpreted as proxies for rates of rock uplift see refs 1 and 2 for example and indices of the strength of climatic forcing of erosion over time see refs 3 and 4 for example this approach implicitly assumes that river incision rates are in equilibrium with external forcings over a wide range of timescales here we directly test this assumption by examining the temporal scaling of bedrock river incision from 155 independent measurements of river incision compiled from 14 sites of these sites 11 exhibit a negative power law dependence of bedrock river incision rate on measurement interval a relationship that is apparent over timescales of 10 4 10 7 years and is independent of tectonic and geomorphic setting thus like rates of sediment accumulation rates of river incision into bedrock exhibit non steady state behaviour even over very long measurement intervals non steady state behaviour can be explained by episodic hiatuses in river incision triggered by alluvial deposition if such hiatuses have a heavy tailed length distribution regardless of its cause the dependence of incision rate on measurement interval complicates efforts to infer tectonic or climatic forcing from changes in rates of river incision over time or from comparison of rates computed over different timescales

migration and shortening rates in the northern apennines italy implications for seismic hazard abstract is compression across the northern apennine fold and thrust system italy still active to address this question we quantified the long term rates of migration and shortening of the system along with the measurement errors our approach integrates structural geology seismicity patterns and statistical treatment of tectonic activity based on recently published surface and subsurface data we found a migration rate of 8 85 0 61 mm y the inception age of individual fold structures follow closely this average rate indicating that the system has been migrating at a constant rate for the past 17 myr cumulative shortening of the system also increases linearly through time at 2 93 0 31 mm y the location of the youngest structures in the easternmost portion of the system coincides with a significant peak of seismic moment released by historical earthquakes we conclude that not only these easternmost thrusts are still active but also that they generate earthquakes keywords

radiocarbon calibration curve spanning 0 to 50 000 years bp based on paired 230 th 234 u 238 u and 14 c dates on pristine corals abstract radiocarbon dating is the most widely used dating technique in the world recent advances in accelerator mass spectrometry ams and sample preparation techniques have reduced the sample size requirements by a factor of 1000 and decreased the measurement time from weeks to minutes today it is estimated that more than 90 percent of all measurements made on accelerator mass spectrometers are for radiocarbon age dates the production of 14 c in the atmosphere varies through time due to changes in the earth s geomagnetic field intensity and in its concentration which is regulated by the carbon cycle as a result of these two variables a radiocarbon age is not equivalent to a calendar age four decades of joint research by the dendrochronology and radiocarbon communities have produced a radiocarbon calibration data set of remarkable precision and accuracy extending from the present to approximately 12 000 calendar years before present this paper presents high precision paired 230 th 234 u 238 u and 14 c age determinations on pristine coral samples that enable us to extend the radiocarbon calibration curve from 12 000 to 50 000 years before present we developed a statistical model to properly estimate sample age conversion from radiocarbon years to calendar years taking full account of combined errors in input ages and calibration uncertainties our radiocarbon calibration program is publicly accessible at http www radiocarbon ldeo columbia edu along with full documentation of the samples data and our statistical calibration model

the river it goes right on post glacial landscape evolution in the upper waipaoa river basin eastern north island new zealand abstract post glacial incision created 50 to 120 m of relief in the headwaters of the waipaoa river basin but it is not known how the signal of incision propagated along the trunk streams we addressed this issue by imposing previously determined long term rates of rock uplift that vary between 0 6 and 4 mm year 1 on the preaggradation longitudinal profile acting over the past 27 1 2 cal ka bp these rates are sufficient to passively elevate the waipaoa 1 terrace to its present level but during the last glacial maximum rates of vertical incision failed to match those of the uplifting rocks thus by the time favorable conditions for incision were reestablished after the antarctic cold new zealand late glacial reversal we estimate that the channel would have been elevated 55 m above the datum the river should otherwise have maintained the channel incised rapidly after the transition from glacial to interglacial conditions and reacquired its steady state form in the mid holocene 5 5 2 cal ka bp thereafter we suggest rates of incision matched rates of uplift no knickpoints are found on the upper waipaoa and mangatu rivers because incision commenced simultaneously along the entire length of the trunk streams and the pattern of incision is consistent with the downstream decline in the rate of rock uplift we also used hypsometric analysis to show how post glacial incision affected the surface morphology of low order 0 1 4 3 km 2 drainages in the headwaters of the waipaoa river basin values of the hypsometric integral are higher for proximal basins which the incision signal did not permeate than for low order basins bordering the upper waipaoa river and the lower reaches of tributaries that possessed enough erosive capacity to keep pace with incision along the mainstem hillslope adjustments were focused on the lower and mid sections of these basins so that the most pronounced changes to the hypsometric curve occur in the vicinity of the toe whereas the entire form of the hypsometric curve changes once mass wasting processes encroach onto hillslopes in the middle and upper sections of a basin

discriminating between tectonic and sedimentary burial in a foredeep succession northern apennines an extensive apatite fission track survey has been carried out on the marnoso arenacea foredeep succession in the northern apennines the data show a general decrease of the maximum paleotemperature undergone by the sediments toward the foreland areas the maximum burial calculated by using a geothermal gradient of 20 c km 1 spans from more than 5 km to less than 2 5 km and indicates that the previously assessed total thickness of the marnoso arenacea succession is not enough to justify the determined values it is concluded that a now eroded ligurian wedge up to 5 km thick was present on top of the marnoso arenacea sediments

immiscible sulfide droplets in pseudotachylyte evidence for high temperature 1200 c melts abstract in the north cascade mountains washington rocks that underwent friction melting commonly contained sulfide minerals mostly pyrrhotite and pyrite during pseudotachylyte melt formation sulfides melted to form immiscible sulfide droplets present in five distinct textural settings the largest droplets formed through melting of lithic clasts whereas micron scale sulfide droplets are common in many of the pseudotachylytes veins microprobe analysis indicates that nearly all droplets are pyrrhotite the disappearance of pyrite indicates that melt temperatures must have exceeded 750 c but other indications suggest that the melt temperature must have been much higher the extremely common presence of pyrrhotite droplets suggests that pyrrhotite from the protolith melted requiring a minimum melt temperature of 1200 c in some samples evidence for fluid rich bubbles and possible silicate spherules indicates three coexisting immiscible phases within the silicate melt the presence of sulfide droplets appears to be common especially in relatively low oxygen fugacity melts that formed at shallow crustal levels this can provide a good textural marker of melting and therefore of pseudotachylyte formation especially where other indications of melting i e high temperature microlites vesicles etc are lacking and illustrates the extreme temperatures possible along frictionally sliding surfaces during seismic events

extensional basins in the tectonically bimodal central apennines fold thrust belt italy response to corner flow above a subducting slab in retrograde motion the apennines fold thrust belt has developed over the past 20 m y in response to southeastward retrograde migration of the adriatic trench in a region of ongoing subduction but little plate convergence the orogenic belt is characterized by a gently sloping southwestern flank in a state of regional extensional collapse and a steeply sloping northeastern flank in regional contraction in any given area in the central apennines the chronologies of thrusting and subsequent extension provide an estimate of the time required for attainment of high elevation 2 5 3 0 km the time between initial extension and eruption of local ultramafic lavas provides an estimate of the time required to collapse by regional crustal thinning these estimates suggest that the northeastern contractional flank of the range is rising at least twice as fast as the southwestern flank is collapsing we propose that the bimodal state of stress in the apennines is maintained by corner flow in the mantle wedge beneath the crest of the range

river response to high frequency climate oscillations in southern europe over the past 200 k y a 200 k y chronology of river response to climate related environmental change has been established for northeast spain using newly developed luminescence dating techniques this constitutes the best documented record of late quaternary river behavior currently available for the north atlantic region and enables fluvial stratigraphies to be compared with high resolution ice core and marine oxygen isotope climate series pleistocene and holocene river aggradational episodes coincide with stadial or neoglacial events while phases of river incision occur during interstadial or interglacial periods alluviation and erosion cycles would appear to track variations in sediment supply controlled by vegetation cover and winter storm frequency

late quaternary fluvial terraces of the romagna and marche apennines italy climatic lithologic and tectonic controls on terrace genesis in an active orogen abstract we synthesize a new fluvial terrace chronostratigraphy of the bidente and musone rivers cast within a broader european framework which forms the basis of a terrace genesis and river incision model for the northern apennines italy our model supported by terrace long profiles correlation to po foreland sediments 15 new radiocarbon dates and published numeric and relative stratigraphic ages highlights how drainage basin substrate drives concurrent formation of strath terraces in the bidente basin and fill terraces in the musone basin quaternary climate change paces the formative geomorphic processes through unsteady discharges of water and sediment in the weathering limited setting represented by the bidente basin siliciclastic detritus carves broad strath surfaces during glacial climates that are preserved as terraces as the river incises during the transition to an interglacial climate in contrast the transport limited and carbonate detritus dominated musone basin sees valleys deeply buried by aggradation during glacial climates followed by river incision during the transition to an interglacial climate incision of these rivers over the past 1 million years has been both unsteady and non uniform these and all po adriatic draining rivers are proximal to a base level defined by mean sea level and have little room for increasing their longitudinal profile concavities through incision particularly in their lower reaches despite periodic glacio eustatic drawdowns as a result the observed incision is best explained by rock uplift associated with active local fault or fold growth embedded in the actively thickening and uplifting apennine foreland

surface movements in bologna po plain italy detected by multitemporal dinsar abstract we studied the surface deformations affecting the southeastern sector of the po plain sedimentary basin in particular the area of bologna to this aim an advanced dinsar technique referred to as dinsar sbas small baseline subset has been applied this technique allows monitoring the temporal evolution of a deformation phenomenon via the generation of mean deformation velocity maps and displacement time series from a data set of acquired sar images in particular we have processed a set of sar data acquired by the european remote sensing satellite ers sensors and compared the achieved results with optical levelling measurements assumed as reference the surface displacements detected by dinsar sbas from 1992 to 2000 are between 10 mm year in the historical part of bologna town and up to 59 mm year in the ne industrial and agricultural areas former measurements from optical levelling referred to 1897 show 2 3 mm year vertical movements this trend of displacement increased in the second half of the 20th century and the subsidence rate reached 60 mm year we compared the more recent levelling campaigns in 1992 and late 1999 and dinsar results from 1992 to 1999 the standard deviation of the difference between levelling data projected onto the satellite line of sight and dinsar results is 2 mm year this highlights a good agreement between the measurements provided by two different techniques the explanation of soil movements based on interferometric results ground data and geological observations allowed confirming the anthropogenic cause surface effect due to the overexploitation of the aquifers and highlights a natural tectonic subsidence

interrelations of mud volcanism fluid venting and thrust anticline folding examples from the external northern apennines emilia romagna italy 1 the present work aims to provide an example of connection between fluid seepage and fault fracture zones associated with compressional thrust folds surface fluid seepage along the pede apennine margin consists of mud volcanism and methane rich emissions showing an intimate link with thrust related folds dominant gaseous or ch4 bearing fluid emissions characterize thrust fold settings in which fluid escape from the main reservoir and source rock i e the marnoso arenacea flysch is not impeded by a seal layer conversely remarkable mud volcanism is closely linked to the presence of the impermeable ligurian units sealing the marnoso arenacea reservoir structural analyses focused on selected thrust folds exhibiting clear relations between surface seepage and brittle elements associated with the fold various scenarios potentially explaining mud volcanism and venting over the crestal region of the thrust related folds are discussed with respect to fluid pressure state and the development of second order fault and fracture sets that are observed to control surface fluid expulsion it is proposed that mud volcanism can be potentially triggered by first order fault failure cycles during which the overpressured fluid is released during faulting events past anomalous eruptions associated with strong earthquakes seem to support this hypothesis the relatively quiescent but continuous activity of the current pede apennine mud volcanoes could instead reflect a short lived leakage of overpressured fluids along permeable fractures faults expansion of methane contained in the rising mud may assist this process fundamentally

plio quaternary vertical motion of the northern apennines insights from dynamic modeling we test the effects of different geodynamic mechanisms on the pliocene to present day dynamics and in particular on the vertical motions of the northern apennines system by means of two dimensional finite element models we show that the pliocene features of the northern apennines exhumation of deep rocks in western italy and fast subsidence rates in the adriatic foredeep can be adequately reproduced by a model slab characterized by the passive sinking of a negatively buoyant adriatic slab and by the upwelling of buoyant asthenosphere beneath western italy model slab is however not able to account for the quaternary and present day pattern of vertical motion of eastern italy and of the adriatic basin a deep configuration of the system characterized by a detached slab model detach may explain the vertical motions of these areas constrained by uplift of the eastern portions of the apenninic chain by an eastward shift of the foredeep depocenter and by lower subsidence rates in the adriatic basin the tectonic and stratigraphic data showing major differences between the tertiary and the quaternary evolution of the northern apennines are discussed

pleistocene fluvial terraces from northern france seine yonne somme synthesis and new results from interglacial deposits the seine yonne and somme are the main rivers draining northwestern france and flowing into the channel during pleistocene cold stages they were tributaries of the fleuve manche they are characterised by well developed stepped terrace systems showing up to 10 incision steps for the last 1 ma after 15 years of research and the synthesis of stratigraphical sedimentological bioclimatical data and numerical dating these terrace systems are interpreted as the response of the fluvial environments to climatic cyclicity superimposed on a background of slow tectonic uplift the comparison of these three terrace systems shows that the incision budget is similar within the studied area about 55 65 m 1 ma implying relative homogeneity of uplift in the main part of the area beyond marine influence the analysis of each stepped alluvial formation shows regular sediment balance generally composed of coarse periglacial gravels pleniglacial covered by fine grained sediments locally overlain by calcareous tufa interglacial however in the lower seine valley close to the present coast the low terrace includes two estuarine interglacial units interbedded within periglacial gravel units nevertheless until recently evidence of full interglacial conditions remained elusive in fluvial contexts especially in the somme to address these issues a new research programme has been launched on tufa deposits that are the best candidate to register the climatic optimum initial results from la celle seine saint acheul and caours somme allow palaeoenvironmental reconstructions of mis 11 and 5e and thus confirm the importance of calcareous tufa to define a reference record of pleistocene interglacials for northern france moreover it has been previously demonstrated that the main incision leading to terrace formation can be attributed to the transition between interglacial and glacial during early glacial phases the new results from interglacial records have important implications concerning the precise occurrence of the major incision phases within the climatic cycle as they provide the starting point immediately preceding downcutting

observations on the role of lithology in strath terrace formation and bedrock channel width field observations from western washington and eastern tibet indicate a strong lithologic influence on strath terrace formation and highlight the response of bedrock channel width to spatial gradients in bedrock erodibility and or rock uplift rates measurements of local bedrock bed and bank erosion rates together with observations of the role of weathering processes on erosion of siltstones and sandstones illustrate a mechanism that underlies a conceptual model that predicts a strong lithological control on strath terrace formation direct measurements of bedrock erosion rates in lithologies susceptible to accelerated erosion upon sub aerial exposure show that lateral rates of bedrock bank erosion can substantially exceed vertical incision below the perennial flow level due to an asymmetry in erodibility between perennially submerged rock and rock exposed to cyclic wetting and drying on bedrock channel walls under such conditions the rapid weathering mediated lowering of bedrock exposed above baseflow promotes development of a beveled bedrock platform that could become a strath terrace upon abandonment in contrast to previous studies channel widths measured across a substantial gradient in lithology slope and long term erosion rates in eastern tibet do not follow conventional relations where channel width scales as a power law function of drainage area instead as they flow across a zone of rapid uplift these channels systematically narrow relative to the predicted width extrapolated from traditional power law relations field studies from a wide range of geological settings and lithologies support the interpretation that in general strath terraces tend to be more extensive in rivers flowing over weak sedimentary rock and tend to be poorly developed and or preserved where rivers flow over hard erosion resistant rock

bedrock incision rock uplift and threshold hillslopes in the northwestern himalayas the topography of tectonically active mountain ranges reflects a poorly understood competition between bedrock uplift and erosion dating of abandoned river cut surfaces in the northwestern himalayas reveals that the indus river incises through the bedrock at extremely high rates 2 12 mm yr 1 in the surrounding mountains the average angles of hillslopes are steep and essentially independent of erosion rate suggesting control by a common threshold process in this rapidly deforming region an equilibrium is maintained between bedrock uplift and river incision with landsliding allowing hillslopes to adjust efficiently to rapid river down cutting

climate driven bedrock incision in an active mountain belt measurements of fluvial bedrock incision were made with submillimeter precision in the east central range of taiwan where long term exhumation rates and precipitation driven river discharge are independently known they indicate that valley lowering is driven by relatively frequent flows of moderate intensity abrasion by suspended sediment is an important fluvial wear process and channel bed geometry and the presence of widely spaced planes of weakness in the rock mass influence erosion rate and style

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

pleistocene incision rates in the western united states calibrated using lava creek b tephra the lava creek b ash bed erupted from the yellowstone caldera ca 0 64 ma provides a datum for measuring long term fluvial incision west of the mississippi river the ash is widely preserved due to its substantial volume broad initial dispersal and the aggrading environment into which the ash fell drainages incised soon after lava creek b deposition isolating the ash from fluvial erosion and preserving it in fill terraces calculated rates of incision since ca 0 60 ma range from 2 to 30 cm k y 1 rates are high in most areas near the rocky mountains and downstream along rivers draining mountainous terrain and are lowest east of the high plains and along the snake river incision rates along many rivers decrease downstream rates of downcutting increased in the late pleistocene along several major rivers indicating that climate change altered sediment budgets regional and temporal data suggest that fluvial incision records increased middle and late pleistocene runoff from the southern rocky mountains rather than epeirogenic uplift but regional rock uplift cannot be excluded as a significant factor

adjustments by the charwell river new zealand to uplift and climatic changes major climatic changes and rapid local and regional tectonic movements were common in new zealand during the late quaternary and caused a diversity of adjustments in the drainage basin and piedmont reaches of the charwell river which are separated by the hope fault the onset of semi arid frigid climates during the latest pleistocene probably greatly increased hillslope sediment yields in a periglacial environment and the piedmont reach aggraded as much as 42 m on top of a broad strath with the return of humid mesic climates in the holocene sediment yields decreased as dense forests again mantled the slopes and the piedmont reach degraded as mush as 81 m dating of eleven cut and strath terraces by radiocarbon calibrated weathering rind measurements on greyawake cobbles shows the degradation rates varied greatly during the last 14 ka 1 ka 1000 yr initial degradation rates of 4 m ka 1 increased to 30 m ka 1 by 6 ka ago during a mid holocene climatic optimum since 4 ka ago degradation rates have been only 1 2 m ka 1 comparable to uplift rates in the piedmont reach inferred from marine terrace studies and the river is again cutting a broad strath each broad strath represents equilibrium conditions attained by this powerful stream during interglacial times despite episodes of being overwhelmed by climatically induced sediment yield increases during full glacial climates and having to maintain a long term degradation rate equal to the uplift rate the 75 81 m of degradation since formation of the latest pleistocene fill terrace tread is the sum of the amount of late pleistocene valley floor aggradation and the amount of regional uplift that occurred between the estimated times of major strath formation at about 30 and 0 ka the 39 m of tectonically induced degradation below the pre aggradation strath is sufficiently large that post 30 ka uplift may have doubled holocene degradation rates each of the eleven degradation terraces represents pauses of a few centuries in holocene downcutting brief equilibrium conditions were attained by streambed armoring and concurrent growth of riparian plants both processes progressively increased hydraulic roughness and the shear stresses needed to entrain streambed materials occasional floods possibly from rare cyclones derived from tropical moisture sources destroyed streambed armor and channel downcutting was renewed thus the formation of eleven equilibrium terraces can be accounted for without postulating additional tectonic perturbations or secular climatic changes

lowstand rivers need not incise the shelf an example from the great barrier reef australia with implications for sequence stratigraphic models a key tenet of many sequence stratigraphic models is that sea level lowering causes widespread fluvial incision of the subaerially exposed continental shelf and that river borne terrigenoclastic sediments bypass the lowstand shoreline via canyons to the continental slope and basin floor consequently the occurrence of incised channels is considered a fundamental criterion for the recognition of sequence boundaries in ancient shelf successions contrary to this we argue that rivers may not necessarily incise during glacio eustatic lowstands if they flow out onto a coastal plain flanked by a broad low angle shelf on the great barrier reef shelf fluvial incision did not occur during the last glacial maximum lgm but instead subaerial accommodation was created and infilled as contemporary rivers graded to the lgm bayline incision was restricted to the lowstand shelf break where canyons of limited extent formed by nickpoint retreat

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

distinguishing between tectonic and lithologic controls on bedrock channel longitudinal profiles using cosmogenic 10be erosion rates and channel steepness index abstract knickpoints in fluvial channel longitudinal profiles and channel steepness index values derived from digital elevation data can be used to detect tectonic structures and infer spatial patterns of uplift however changes in lithologic resistance to channel incision can also influence the morphology of longitudinal profiles we compare the spatial patterns of both channel steepness index and cosmogenic 10be determined erosion rates from four landscapes in italy where the geology and tectonics are well constrained to four theoretical predictions of channel morphologies which can be interpreted as the result of primarily tectonic or lithologic controls these data indicate that longitudinal profile forms controlled by unsteady or nonuniform tectonics can be distinguished from those controlled by nonuniform lithologic resistance in each landscape the distribution of channel steepness index and erosion rates is consistent with model predictions and demonstrates that cosmogenic nuclide methods can be applied to distinguish between these two controlling factors

late quaternary stream incision and uplift in the forearc of the cascadia subduction zone western oregon documentation of a latest pleistocene earliest holocene episode of strath formation and fluvial aggradation in the oregon coast range provides a datum from which long term bedrock stream incision rates are determined variations in long term incision rates probably reflect cumulative differential uplift in the forearc of the cascadia subduction zone although factors such as bedrock and climatic controls and isostatic adjustments to erosion obscure the precise relationship between surface uplift and stream incision patterns of differential incision are most striking near the latitude of newport where a steep gradient divides a region of higher rates 0 6 0 9 mm yr in the northern coast range from a region of lower rates 0 1 0 3 mm yr in the central coast range the steep incision gradient is nearly coincident with abrupt changes in marine terrace 80 125 kyr uplift rates the locations of quaternary faults and the southern flank of a saddle of low historic 40 70 years uplift the exact causes of these variable patterns of incision uplift are unknown analogies with uplift patterns in other subduction zones and comparisons with other neotectonic data in the region indicate that patterns of differential incision probably are caused by variations in permanent strain accumulation along the cascadia subduction zone such variations may be related to differences in seismic moment release during individual earthquakes to changes in plate geometry or rates of wedge accretion to segmentation of earthquake ruptures and or to deformation on active structures in the north american plate and accretionary wedge

geomorphic response of coastal streams to low intermediate and high rates of uplift medocino triple junction region northern california analysis of three dimensional morphological properties of 24 coastal drainage basins that have evolved in areas of low 3 m 1 000 yr rates of uplift near the mendocino triple junction mtj coastal northern california identified channel gradients as the best indicator of tectonism in the landscape lower order tributaries best reflect tectonically controlled differences the largest streams examined of third order are able to adjust to most base level change and maintain their profile form whereas lower order streams farther upstream tend to accumulate the effects of net base level fall and have steepest profiles in the areas of highest uplift rates variations in steepness of first order channel gradients indicate that 1 high uplift rates in the wake of the mtj have existed for at least 73 000 yr and 2 differential tilt of the region to the north and south of the current locus of highest uplift rate is occurring in association with regional uplift although first order streams are excellent indicators of areas of both high uplift rates and regional differential tilting they are less useful in distinguishing between areas of low and intermediate uplift rate analysis of the longitudinal profile of the main trunk stream of ten of the 24 drainage basins using the stream gradient index was more useful to categorize broadly the uplift rates and to distinguish between streams in low and intermediate uplift rate areas although the hypotheses tested herein do not identify the exact mechanism off uplift in the mtj region they do indicate that the nature of deformation is most likely regional tilt rather than crustal shortening with localized compressional folding and thrust faulting they also indicate that geomorphic responses trail in the wake of the uplift rate response caused by development of a slab window beneath the north american plate 1 maximum uplift rates occur 9 km south of the northern boundary of the slab window 2 maximum mean first order channel gradient occurs 16 km south of the northern edge of the slab window and 3 maximum drainage basin relief occurs 20 km south of the northern edge of the slab window associated lag times between passage of the southern edge of the subducted gorda plate slab and geomorphic responses are 160 000 yr for maximum uplift rates 290 000 yr for maximum channel gradients and 370 000 yr for maximum relief