paleozoic metasomatism at the origin of mediterranean ultrapotassic magmas constraints from time dependent geochemistry of colli albani volcanic products central italy abstract the major processes that control the genesis of potassic volcanic rocks like the timing of multi stage mantle metasomatism remain largely unclear in an attempt to clarify the timing of the metasomatic process a detailed geochronologic and geochemical study has been conducted on the ultrapotassic rocks of the colli albani volcanic district central italy new 40 ar 39 ar data coupled with literature and newly performed 87 sr 86 sr 143 nd 144 nd and chemical data allow us to precisely delineate the time dependent geochemical variations of the magmas erupted at the colli albani volcanic district and to better define mantle source processes responsible for their genesis the temporal geochemical variations observed in the colli albani magmas indicate that i the ultrapotassic magmas originated from a metasomatized mantle source in which phlogopite is the potassium bearing phase ii the partial melting of the mantle source involved mainly phlogopite and clinopyroxene olivine whereas the role of accessory phases was less significant and iii the metasomatic process that led to the formation of the phlogopite in the mantle can be reasonably related to events that have occurred during the paleozoic era

major explosive activity in the monti sabatini volcanic district central italy over the 800 390 ka interval geochronological geochemical overview and tephrostratigraphic implications abstract a review of the existing chronological stratigraphic and chemo petrologic data of the major eruptive units from the early phase of activity 800 390 ka in the monti sabatini volcanic district msvd belonging to the ultra potassic magmatic region of central italy is presented along with new radioisotopic age determinations and geochemical analyses through the combined use of electron microprobe glass compositions selected trace element compositions and single crystal 40ar 39ar age determinations we provide a new chrono and chemo stratigraphic classification of the products emplaced in the 800 390 ka time interval besides giving insights on the petrologic evolution of the roman comagmatic region the large dataset provides fundamental information that is applicable to tephrostratigraphic studies in the wide region encompassing the tyrrhenian sea margin to the adriatic sea basin distal tephras from this volcanic activity also act as important geochronologic markers for the coastal sedimentary successions deposited in response to glacio eustatic fluctuations as well as for successions in the quaternary tectonic basins of the central and southern apennines an innovative approach based on the use of discrimination diagrams of zr y vs nb y ratios for fingerprinting altered volcanic rocks recently developed and successfully employed in archaeometric studies is here combined to the glass compositions for classifying the msvd deposits and tested on two distal tephra layers showing its potentiality for tephrostratigraphic correlation

the colli albani mafic caldera roma italy stratigraphy structure and petrology new results for the colli albani volcano roma italy surveyed for the geological map of italy at 1 50 000 scale carg project integrated with previous data provide insights on caldera evolution the colli albani a quiescent volcano became active at 600 ka eruptive compositions are consistently mafic 50 km 3 deposits forming the villa senni eruption unit ignimbrites at ca 355 ka two edifices were built within the caldera 1 the horseshoe shaped tuscolano artemisio ta composite edifice or lithosome consists of coalescing peri caldera fissure related scoriae cones interbedded with lava flows the fissure system forms two segments controlled by regional fractures 2 the steep sided faete stratovolcano 949 m a s l filled the caldera the ta and faete lithosomes partly interfinger and were emplaced at 350 260 ka their products indicate reduced eruption rates relative to the vl period and a change to effusive and mildly explosive eruptions the most recent and still active phase of phreatomagmatic activity formed overlapping maars and tuff cones along the western and northern slopes of the volcano collectively named via dei laghi composite lithosome the colli albani caldera is poly phase 1 a piecemeal caldera is associated with large volume ignimbrites of the vl edifice the present shape of the caldera is related to the villa senni eruption 2 the ta composite edifice erupted from peripheral caldera fissures is unrelated to explosive phases of caldera collapse the ta final products cover a morphologically stable caldera wall the peripheral fractures feeding the ta composite edifice are interpreted as volcano tectonic structures activated during the late stage downsag of the caldera reduced eruption rates during the ta and the faete stages 10 1 km 3 1 ka respect to 10 0 km 3 1 ka for the vl edifice suggest a reduced recharge of the magma chamber that may have induced prolonged deflation and downsagging of the caldera floor and the opening of outward dipping peripheral fractures by this interpretation the ta edifice represents the surface expression of ring dykes at depth the absence of similar fissure structures along the western caldera rim may relate to the deep geometry of the ring faults dipping inward in those areas and therefore not favourably oriented for magma intrusion during a period of general subsidence by contrast the following and still active phreatomagmatic phase that has emplaced the via dei laghi composite edifice is located right on the western side of the caldera and may therefore relate to resurgent conditions classical petrological and pers pearce elements ratios analyses indicate that lavas are co genetic and show a differentiation trend up through stratigraphy driven by

history of glacial terminations from the tiber river rome insights into glacial forcing mechanisms 1 we document the aggradational history of the tiber river delta through the last 17 000 years by means of 17 new 14c ages from peat or wood collected from the delta sediment an abrupt change in sediment clast size grading from gravel to clay occurred between 13 63 0 20 and 12 80 0 15 ka indicating that it was synchronous with the last glacial termination with no appreciable phase lag knowing this phase relationship enables us to reduce the magnitudes of age uncertainties for aggradational sections corresponding to glacial terminations ix through iii which we had dated previously by 40ar 39ar methods glacial terminations viii vi and iv precede beyond 95 confidence the ages predicted by northern hemisphere summer insolation maxima additionally we find that each of these seven glacial terminations follows particularly mild insolation minima which we suggest may be regarded as the preconditioning factor to trigger a glacial termination

revised chronology of the sulmona lacustrine succession central italy we present new stratigraphic palaeomagnetic 87sr 86sr and 40ar 39ar data from a lacustrine succession of the sulmona basin central italy which according to an early study included six unconformity bounded lacustrine units from sul6 oldest to sul1 youngest spanning the interval 600 to 2 ka the results of the present study on the one hand confirm some of the previous conclusions but by contrast reveal that units sul2 and sul1 previously attributed to the holocene are actually equivalent to the older sul6 and sul5 units here dated to 814 530 ka and 530 457 ka respectively and that the u series dates previously published for both former sul2 and sul1 units yielded abnormally young ages in light of the present results a reassessment of the chronology of the sulmona basin succession and a revision of the tephrostratigraphy of the sul2 sul6 and sul1 sul5 units is in order copyright 2013 john wiley sons ltd

ambiguities in human and elephant interactions stories of bones sand and water from castel di guido italy geoarchaeological and taphonomical studies have been carried out on the sequence and on the faunal remains of castel di guido central italy a middle pleistocene site with acheulean industry and faunas including elephas palaeoloxodon antiquus bos primigenius equus ferus and other taxa investigation focused on remains accumulated on the bottom of a depressed area probably an ephemeral stream channel sometimes acting as a seep the assemblage resulted prevalently from human activity as shown by the selection of the faunas by the thorough fracturing of the bones and by the occurrence of abundant chipped stone industry and bone bifaces it is still a matter of debate whether the animals were hunted or scavenged the present day distribution of the remains does not represent exactly their original configuration as in most sites of this type and age more likely the objects are partly in their original position and partly reworked and lie within a complex palimpsest of several phases of fluvial transport and human activity with the addition of external inputs of reworked bones and artefacts

comparison of changes in vegetation in northeast greece with records of climate variability on orbital and suborbital frequencies over the last 450 000 years abstract a new direct pollen orbital tuning procedure based on a correspondence between changes in certain vegetation elements and march and june perihelion configurations is applied to the tenaghi philippon record northeast greece the development of a refined chronological scheme allows comparisons to be made with records of climate variability from the north atlantic as well as of global sea level ice volume and atmospheric co2 content on orbital frequencies the comparison reveals a close correspondence between relative ice volume extent and tree population size during glacial intervals during interglacial and interstadial periods the degree of forest development is more closely associated with high latitude insolation and related climate regimes rather than extent of residual ice volume on suborbital frequencies the greek record shows similar repeat times in peaks of steppe vegetation with north atlantic ice rafting events but the amplitude of this variability in the two records is not always proportional overall what emerges is that the major shifts in the relative abundance of forest v open vegetation communities at tenaghi philippon on orbital and suborbital frequencies over the last 450 000 years are coherent with high latitude changes affecting atmospheric and oceanic circulation glacial decreases in atmospheric co2 content contributed to the elimination of tree populations by exacerbating water stress conditions during arid intervals but do not appear to be the primary driver of the observed vegetation changes at this latitude variations in co2 levels in the order of 40 ppmv between different interglacial interstadials periods with adequate moisture availability appear to have had a limited effect on the nature and size of tree populations

tephrochronology of core prad 1 2 from the adriatic sea insights into italian explosive volcanism for the period 200 80 ka core prad 1 2 located on the western flank of the mid adriatic deep was investigated for tephra content within the part of the sequence assigned on biostratigraphic and sapropel layer stratigraphy to mis 5 and 6 ca 80 200 ka bp a total of 11 discrete tephra layers are identified 8 visible and 3 cryptotephra layers 235 geochemical measurements obtained from individual glass shards using wds epma enabled 8 of the 11 tephras to be correlated to known eruption events 5 of which are represented in the lago grande di monticchio lgdm regional tephra archive sequence three of these layers are recognised ultra distally for the first time extending their known distributions approximately 210 km further north the results provide an independent basis for establishing an age depth profile for the mis 5 6 interval in the prad 1 2 marine record this approach allowed age estimates to be interpolated for the tephra layers that could not be correlated to known events it also provides an independent test of and support for the broad synchroneity of sapropel equivalent s e events in the adriatic sea with the better developed sapropel layers of the eastern mediterranean proposed by piva et al 2008a

epica dome c record of glacial and interglacial intensities abstract climate models show strong links between antarctic and global temperature both in future and in glacial climate simulations past antarctic temperatures can be estimated from measurements of water stable isotopes along the epica dome c ice core over the past 800 000 years here we focus on the reliability of the relative intensities of glacial and interglacial periods derived from the stable isotope profile the consistency between stable isotope derived temperature and other environmental and climatic proxies measured along the edc ice core is analysed at the orbital scale and compared with estimates of global ice volume mis 2 12 and 16 appear as the strongest glacial maxima while mis 5 5 and 11 appear as the warmest interglacial maxima the links between edc temperature global temperature local and global radiative forcings are analysed we show i a strong but changing link between edc temperature and greenhouse gas global radiative forcing in the first and second part of the record ii a large residual signature of obliquity in edc temperature with a 5 ky lag iii the exceptional character of temperature variations within interglacial periods focusing on mis 5 5 the warmest interglacial of edc record we show that orbitally forced coupled climate models only simulate a precession induced shift of the antarctic seasonal cycle of temperature while they do capture annually persistent greenland warmth models fail to capture the warming indicated by antarctic ice core d we suggest that the model data mismatch may result from the lack of feedbacks between ice sheets and climate including both local antarctic effects due to changes in ice sheet topography and global effects due to meltwater thermohaline circulation interplays an mis 5 5 sensitivity study conducted with interactive greenland melt indeed induces a slight antarctic warming we suggest that interglacial edc optima are caused by transient heat transport redistribution comparable with glacial north south seesaw abrupt climatic changes

a continuous stable isotope record from the penultimate glacial maximum to the last interglacial 159 121 ka from tana che urla cave apuan alps central italy abstract relatively few radiometrically dated records are available for the central mediterranean spanning the marine oxygen isotope stage 6 5 mis 6 5 transition and the first part of the last interglacial two flowstone cores from tana che urla cave tcu central italy constrained by 19 u th ages preserve an interval of continuous speleothem deposition between ca 159 and 121 ka a multiproxy record 18 o 13 c growth rate and petrographic changes obtained from this flowstone preserves significant regional scale hydrological changes through the glacial interglacial transition and multi centennial variability interpreted as alternations between wetter and drier periods within both glacial and interglacial stages the glacial stage shows a wetter period between ca 154 and 152 ka while the early to middle last interglacial period shows several drying events at ca 129 126 and 122 ka which can be placed in the wider context of climatic instability emerging from north atlantic marine and nw european terrestrial records the tcu record also provides important insights into the evolution of local environmental conditions i e soil development in response to regional and global scale climate events

timing of magmatism basin formation and tilting at the west edge of the colorado river extensional corridor results from single crystal40ar 39ar geochronology of tertiary rocks in the old woman mountains area southeastern california tertiary basin development volcanism and structural tilting at the west edge of the colorado river extensional corridor is examined using single crystal 40ar 39ar ages from volcanic rocks in ship piute little piute and northern old woman mountains old woman mountains area complications in age determination resulting from xenocrystic contamination and common excess trapped ar are readily circumvented using single crystal analysis preferred ages indicate that the two thickest sections of tertiary strata in the ship and little piute mountains were deposited between about 19 19 5 ma and 17 ma the earliest tertiary magmatism in the area is recorded by a 21 ma dike from the northern old woman mountains but no volcanic units older than 19 3 ma have been dated this earliest diking correlates with the initial phases of volcanism to the east in the colorado river trough westward tilting of the little piute mountains occurred after 17 8 ma uppermost tuff and final westward tilting of the piute moun

duration and dynamics of the best orbital analogue to the present interglacial past orbital analogues to the current interglacial such as marine isotope stage 19c mis 19c ca 800 ka can provide reliable reference intervals for evaluating the timing and the duration of the holocene and factors inherent in its climatic progression here we present the first high resolution paleoclimatic record for mis 19 anchored to a high precision 40ar 39ar chronology thus fully independent of any a priori assumptions on the orbital mechanisms underlying the climatic changes it is based on the oxygen isotope compositions of italian lake sediments showing orbital to millennial scale hydrological variability over the mediterranean between 810 and 750 ka our record indicates that the mis 19c interglacial lasted 10 8 3 7 k y comparable to the time elapsed since the onset of the holocene and that the orbital configuration at the time of the following glacial inception was very similar to the present one by analogy the current interglacial should be close to its end however greenhouse gas concentrations at the time of the mis 19 glacial inception were significantly lower than those of the late holocene suggesting that the current interglacial could have already been prolonged by the progressive increase of the greenhouse gases since 8 6 ka possibly due to early anthropogenic disturbance of vegetation

high level triggers for explosive mafic volcanism albano maar italy abstract colli albani is a quiescent caldera complex located within the roman magmatic province rmp italy the recent via dei laghi phreatomagmatic eruptions led to the formation of nested maars albano maar is the largest and has erupted seven times between ca 69 33 ka the highly explosive nature of the albano maar eruptions is at odds with the predominant relatively mafic sio 2 48 52 wt foiditic k 2 o 9 wt composition of the magma the deposits have been previously interpreted as phreatomagmatic however they contain large amounts up to 30 vol of deep seated xenoliths skarns and all pre volcanic subsurface units all of the xenoliths have been excavated from depths of up to 6 km rather than being limited to the depth at which magma and water interaction is likely to have occurred suggesting an alternative trigger for eruption high precision geochemical glass and mineral data of fresh juvenile magmatic clasts from the small volume explosive deposits indicate that the magmas have evolved along one of two evolutionary paths towards foidite or phonolite the foiditic melts record ca 50 mixing between the most primitive magma and ca rich melt late stage prior to eruption a major result of our study is finding that the generation of ca rich melts via assimilation of limestone may provide storage for significant amounts of co 2 that can be released during a mixing event with silicate magma differences in melt evolution are inferred as having been controlled by variations in storage conditions residence time and magma volume

a multi proxy record of mis 11 12 deglaciation and glacial mis 12 instability from the sulmona basin central italy abstract a multi proxy record lithology xrf caco 3 content carbonate 18 o and 13 c was acquired from a sediment core drilled in the intermountain sulmona basin central italy tephrostratigraphic analyses of three volcanic ash layers ascribe the investigated succession to the mis 12 mis 11 period spanning the interval ca 500 410 ka litho pedo facies assemblage indicates predominant lacustrine deposition interrupted by a minor sub aerial and lake low stand episode variations in major and minor elements concentrations are related to changes in the clastic input to the lake the oxygen isotopic composition of carbonate 18 o c intervals is interpreted mainly as a proxy for the amount of precipitation in the high altitude catchment of the karst recharge system the record shows pronounced hydrological variability at orbital and millennial time scales which appears closely related to the northern hemisphere summer insolation pattern and replicates north atlantic and west mediterranean sea surface temperature sst fluctuations the mis 12 glacial inception is marked by an abrupt reduction of precipitation lowering of the lake level and enhanced catchment erosion a well defined and isotopically prominent interstadial with increased precipitation maybe related to insolation maxima precession minima at ca 465 ka this interstadial ends abruptly at ca 457 ka and it is followed by a phase of strong short term instability drastic lake level lowering and enhanced clastic flux characterized the mis 12 glacial maximum lacustrine deposition restarted about 440 ka ago the mis 12 mis 11 transition is characterized by a rapid increase in the precipitation lake level rise and reduction in the clastic input interrupted by a short and abrupt return to drier conditions comparison with marine records from the iberian margin and western mediterranean suggests that major events of ice rafted debris deposition related to southward migrations of the polar front match the harshest periods in central italy this indicates strong teleconnections between northern hemisphere ice sheet dynamics north atlantic oceanic conditions and mediterranean continental hydrology

tephrochronology of the central mediterranean mis 11c interglacial 425 395 ka new constraints from the vico volcano and tiber delta central italy abstract through a systematic integrated approach which combined lithostratigraphic geochronological and geochemical analyses of tephra from near source sections of the peri tyrrhenian volcanoes and mid to distal settings here we provide an improved tephrochronological framework for the marine isotope stage 11c interglacial mis 11c 425 395 ka in the central mediterranean area specifically we present the complete geochemical dataset and new high precision 40ar 39ar ages of the previously poorly characterized earliest pyroclastic products of the vico volcano 420 400 ka including the plinian eruptions of vico and vico and the immediately post dating lower magnitude explosive events furthermore we also provide new geochronological and geochemical data for the distal tephra layers preserved in the aggradational succession of the tiber delta san paolo formation roman area which records sea level rise relating to the mis 12 glacial to mis 11 interglacial transition five pyroclastic units were recognized in vico volcanic area four out of which vico vico vico top a minor eruption immediately following vico and temporally very close to it and vico were directly dated at 414 8 2 2 ka 406 5 2 4 ka 406 4 2 0 ka and 399 7 3 2 ka respectively 2 analytical uncertainties these new data allow a critical reappraisal of the previously claimed identifications of vico tephra from mid distal to ultra distal successions i e vico sabatini volcanic districts roman san paolo formation and castel di guido archaeological site sulmona basin valdarno and lake ohrid which were unavoidably biased by the poor and incomplete geochemical and geochronological reference datasets previously available such an improvement of the tephrochronological framework brings great benefits to any future investigations e g paleoclimatology archaeology active tectonic volcanology in the dispersal areas of the studied eruptions at the key point in time that is mis 11

sea level rise due to polar ice sheet mass loss during past warm periods background although thermal expansion of seawater and melting of mountain glaciers have dominated global mean sea level gmsl rise over the last century mass loss from the greenland and antarctic ice sheets is expected to exceed other contributions to gmsl rise under future warming to better constrain polarice sheetresponse to warmer temperatures we draw on evidence from in terglacial periods in the geologic record that ex perienced warmer polar temperatures and higher gmsls than present coastal records of sea level from these previous warm periods dem onstrate geographic variability because of the influence of several geophysical processes that operate across a range of magnitudes and time scales inferring gmsl and ice volume changes from these reconstructions is nontrivial and generally requires the use of geophysical models advances interdisciplinary studies of geo logic archives have ushered in a new era of deciphering magnitudes rates and sources of sea level rise advances in our understanding of polar ice sheet response to warmer climates have been made through an increase in the number and geographic distribution of sea level reconstructions better ice sheet constraints and the recognition that several geophysical processes cause spatially complex patterns in sea level in particular accounting for glacial isostatic processes helps to decipher spatial variability in coastal sea level records and has reconciled a number of site specific sea level reconstructions for warm periods that have oc curred within the past several hundred thou sand years this enables us to infer that during recent interglacial periods small increases in

coupling of p t t d histories of eclogite and metagreywacke insights to late ordovician silurian crustal folding events recorded in the beishan orogen nw china

a high resolution tephrochronological record of mis 14 12 in the southern apennines acerno basin italy abstract lithological mineralogical and glass chemical analyses on juvenile fragments extracted from 20 tephra layers embedded within the lacustrine sediments of the acerno basin southern apennines italy were carried out together with four sanidine 40 ar 39 ar age determinations the measured ages span the interval between 561 and 493 ka middle pleistocene eruptive activity at roman province volcanoes was identified as the main possible source of the investigated tephra layers some of them were correlated with precise terrestrial counterparts corresponding to large explosive events of the sabatini e g tufo giallo della via tiberina and alban hills volcanic districts e g tufo pisolitico di trigoria the integration of tephrochronology and pollen analyses allowed the acerno lacustrine sedimentation to be constrained between mis 14 and 12 which overlaps with several well studied lacustrine successions of the southern apennines the correlation with other tephrostratigraphic records from intramontane basins in central southern apennines testifies to the wide dispersal of at least three tephra layers that serve as marker layers thus improving the resolution of the middle pleistocene italian tephrostratotype

silver creek caldera the tectonically dismembered source of the peach spring tuff sanidine 40 ar 39 ar geochronology confirms that silver creek caldera which straddles the eastern edge of the colorado river extensional corridor near oatman arizona united states is the source of the peach spring tuff eight new dates five from outflow three from caldera fill are analytically indistinguishable and combined with the most precise previously published date give a weighted mean average age of 18 78 0 02 ma a fragment of the caldera identified in the midst of the extensional corridor is structurally juxtaposed with mesozonal plutons of identical age the implied extension direction 182 225 is compatible with abundant previously published structural data for the region

plateau style accumulation of deformation southern altiplano 1 employing surface mapping of syntectonic sediments interpretation of industry reflection seismic profiles gravity data and isotopic age dating we reconstruct the tectonic evolution of the southern altiplano 20 22 s between the cordilleras defining its margins the southern altiplano crust was deformed between the late oligocene and the late miocene with two main shortening stages in the oligocene 33 27 ma and middle late miocene 19 8 ma that succeeded eocene onset of shortening at the protoplateau margins shortening rates in the southern altiplano ranged between 1 and 4 7 mm yr with maximum rates in the late miocene summing rates for the southern altiplano and the eastern cordillera we observe an increase from eocene times to the late oligocene to some 8 mm yr followed by fluctuation around this value during the miocene prior to shutoff of deformation at 7 8 ma and transfer of active shortening to the sub andean fold and thrust belt shortening inverted early tertiary graben and half graben systems and was partitioned in three fault systems in the western central and eastern altiplano respectively the east vergent fault systems of the western and central altiplano were synchronously active with the west vergent altiplano west flank fault system from these data and from section balancing we infer a kinematically linked western altiplano thrust belt that accumulated a minimum of 65 km shortening evolution of this belt contrasts with the eastern cordillera which reached peak shortening rates 8 mm yr in between the above two stages hence local shortening rates fluctuated across the plateau superimposed on a general trend of increasing bulk rate with no trend of lateral propagation this observation is repeated at the shorter length and time scales of individual growth structures that show evidence for periods of enhanced local rates at a timescale of 1 3 myr we interpret this irregular pattern of deformation to reflect a plateau style of shortening related to a self organized state of a weak crust in the central south american back arc with a fault network that fluctuated around the critical state of mechanical failure tuning of this state may have occurred by changes in plate kinematics during the paleogene initially reactivating crustal weak zones and by thermal weakening of the crust with active magmatism mainly in the neogene stage

the earliest securely dated hominin fossil in italy and evidence of acheulian occupation during glacial mis 16 at notarchirico venosa basilicata italy the early middle pleistocene site of notarchirico basilicata italy is a 7 m thick fluvially emplaced sedimentary sequence rich in volcanic materials coming from the monte vulture stratovolcano this site consists of 11 archaeological layers some of which have yielded handaxes one femur attributed to homo heidelbergensis was also recovered from an upper level we present in this study new 40ar 39ar and electron spin resonance ages that delimit the time of occupation of notarchirico to between 670 4 ka 14 ka and 614 4 ka 12 ka therefore spanning mainly the glacial marine isotope stage 16 handaxes found in archaeosurface f are now securely dated to between 670 4 ka 14 ka and 661 4 ka 14 ka and prove that hominid populations living in southern italy used acheulian technology as early as the beginning of this stage futhermore we placed the age of the human femur between 661 4 ka 14 ka and 614 4 ka 12 ka this fossil is therefore the oldest middle pleistocene human fossil discovered in italy so far thanks to this new chronological framework notarchirico is now a key site in our understanding of the early acheulian culture in western europe

late stage evolution of the chemehuevi and sacramento detachment faults from apatite u th he thermochronometry evidence for mid miocene accelerated slip the unique low temperature sensitivity of the apatite u th he ahe technique provides valuable new information relating to the late stage thermal evolution of metamorphic core complexes in the southern basin and range province in all the ranges studied the data show greater complexity than previously seen from other thermochronometers in the chemehuevi and northern sacramento mountains a trend of decreasing ages toward the northeast applies only for the structurally shallowest parts of the footwall this is followed by essentially age invariant segments of 15 1 ma reflecting an increase in the rate of detachment fault movement the timing of the change suggested by the data agrees with recently published ahe results from the nearby harcuvar mountains located 125 km to the southeast suggesting that an underlying regional mechanism triggered this change plate reconstructions indicate that the pioneer mendocino fracture zone migrated northward through the area at this time leaving a slab window in its wake we suggest that the additional heat applied to the base of the lithosphere from the slab window resulted in mechanical weakening of the area and that this combined with the extensional strain regime present resulted in an increased rate of slip within the actively extending metamorphic core complexes this agrees well with timing constraints for extension onset in the central basin and range province of southern nevada and suggests that weakening of the southern basin and range province at 15 1 ma was partially responsible for the onset of extension in the central basin and range these findings demonstrate that improved constraints on changes in extension rate within the basin and range province should be possible through the application of the ahe technique to other metamorphic core complex footwalls

mid cenozoic tectonic and paleoenvironmental setting of the central arctic ocean drilling results from the integrated ocean drilling program s arctic coring expedition acex to the lomonosov ridge lr document a 26 million year hiatus that separates freshwater influenced biosilica rich deposits of the middle eocene from fossil poor glaciomarine silty clays of the early miocene detailed micropaleontological and sedimentological data from sediments surrounding this mid cenozoic hiatus describe a shallow water setting for the lr a finding that conflicts with predrilling seismic predictions and an initial postcruise assessment of its subsidence history that assumed smooth thermally controlled subsidence following rifting a review of cenozoic tectonic processes affecting the geodynamic evolution of the central arctic ocean highlights a prolonged phase of basin wide compression that ended in the early miocene the coincidence in timing between the end of compression and the start of rapid early miocene subsidence provides a compelling link between these observations and similarly accounts for the shallow water setting that persisted more than 30 million years after rifting ended however for much of the late paleogene and early neogene tectonic reconstructions of the arctic ocean describe a landlocked basin adding additional uncertainty to reconstructions of paleodepth estimates as the magnitude of regional sea level variations remains unknown

the history of the monti sabatini and alban hills volcanoes groundwork for assessing volcanic tectonic hazards for rome abstract the volcanic rocks of rome provide chronostratigraphic constraint that is of use to geologists archaeologists and paleontologists identifying the areal distribution of these rocks their mode of emplacement and a detailed chronology of the eruptive events also is crucial for assessing local natural hazards in a volcanic tectonic context and for recognizing whether the volcanoes may erupt again in the future we have identified and dated many of the volumetrically significant eruptive units from the monti sabatini and alban hills colli albani and propose a formalized volcanic stratigraphy for rome it is probable that seismic events triggered some eruptions as several ignimbrites from the two volcanoes have statistically indistinguishable ages following a 200 kyr period of dormancy that was coincident with a pulse of regional uplift the alban hills appears to have begun recently circa 45 ka a new eruptive cycle therefore accurate assessment of volcanic tectonic hazards and estimation of possible future volcanic activity is necessary for the safety of the five million people living near these volcanoes

quantifying volcanic ash dispersal and impact of the campanian ignimbrite super eruption 1 we apply a novel computational approach to assess for the first time volcanic ash dispersal during the campanian ignimbrite italy super eruption providing insights into eruption dynamics and the impact of this gigantic event the method uses a 3d time dependent computational ash dispersion model a set of wind fields and more than 100 thickness measurements of the ci tephra deposit results reveal that the ci eruption dispersed 250 300 km 3 of ash over 3 7 million km 2 the injection of such a large quantity of ash and volatiles into the atmosphere would have caused a volcanic winter during the heinrich event 4 the coldest and driest climatic episode of the last glacial period fluorine bearing leachate from the volcanic ash and acid rain would have further affected food sources and severely impacted late middle early upper paleolithic groups in southern and eastern europe citation costa a a folch g macedonio b giaccio r isaia and v c smith 2012 quantifying volcanic ash dispersal and impact of the campanian ignimbrite super eruption geophys res lett 39 l10310 doi 10 1029 2012gl051605

paleomagnetism and geochronology of early middle pleistocene depositional sequences near rome comparison with the deep sea δ18o record abstract a sequence stratigraphic analysis was carried out on clastic coastal deposits ponte galeria formation pgf of the tiber river delta cropping out to the southwest of rome in order to correlate these sequences to pleistocene eustasy tectonic subsidence affected sedimentation but is distinguished from the glacio eustatic signal showing that the pgf consists of four depositional sequences that correlate to two fourth order cycles a paleomagnetic investigation of clay horizons deposited before and after the brunhes matuyama reversal combined with 40 ar 39 ar ages from a tuff horizon within the pgf constrain the timing of the relative sea level changes and allow us to tie it to the astronomically calibrated deep sea 18 o record the brunhes matuyama boundary in the pgf postdates a set of highstand systems tract sediments suggesting that the reversal occurs late in 18 o stage 19 this position is consistent with the recent study of deep sea cores by bassinot et al earth planet sci lett 126 1994 91 108 the assumption of a common continental stage marking the start of the middle pleistocene 18 o stage 22 in the mediterranean region is not supported by the tiber river sections which in our interpretation begin at stage 20

tephrostratigraphy chronology and climatic events of the mediterranean basin during the holocene an overview the identification and characterisation of high frequency climatic changes during the holocene requires natural archives with precise and accurate chronological control which is usually difficult to achieve using only 14c chronologies the presence of time spaced tephra beds in quaternary mediterranean successions represents an additional independent tool for dating and correlating different sedimentary archives these tephra layers are potentially useful for resolving long standing issues in paleoclimatology and can help towards correlating terrestrial and marine paleoclimate archives known major tephras of regional extent derive from central and southern italy the hellenic arc and from anatolia a striking feature of major holocene tephra deposition events in the mediterranean is that they are clustered rather than randomly distributed in time several tephra layers occurred at the time of the s1 sapropel formation between c 8 4 and 9 0 ka bp mercato gabellotto fiumebianco e1 cappadocia and ot

sea level and deep sea temperature variability over the past 5 3 million years ice volume and hence sea level and deep sea temperature are key measures of global climate change sea level has been documented using several independent methods over the past 0 5 million years myr older periods however lack such independent validation all existing records are related to deep sea oxygen isotope 18o data that are influenced by processes unrelated to sea level for deep sea temperature only one continuous high resolution mg ca based record exists with related sea level estimates spanning the past 1 5 myr here we present a novel sea level reconstruction with associated estimates of deep sea temperature which independently validates the previous 0 1 5 myr reconstruction and extends it back to 5 3 myr ago we find that deep sea temperature and sea level generally decreased through time but distinctly out of synchrony which is remarkable given the importance of ice albedo feedbacks on the radiative forcing of climate in particular we observe a large temporal offset during the onset of plio pleistocene ice ages between a marked cooling step at 2 73 myr ago and the first major glaciation at 2 15 myr ago last we tentatively infer that ice sheets may have grown largest during glacials with more modest reductions in deep sea temperature a novel approach to the estimation of sea level and deep sea temperature has been used to determine these quantities over the past 5 3 million years this approach based on oxygen isotope records from the eastern mediterranean shows that temperature and sea level histories are broadly correlated but also show intriguing temporal offsets most records of past sea level variation and associated changes in ocean temperature rely on variations in oxygen isotopes recorded in deep sea marine microorganisms these signals unfortunately are confounded by other influences making it difficult to extract a clear climate related signal eelco rohling and colleagues now present a novel approach to estimating sea level and deep sea temperature variations for the past 5 3 million years the record based on oxygen isotope variations from the eastern mediterranean avoids the issues of the deep sea approach and generally corresponds to an independent record of the past 1 6 million years as expected temperature and sea level are broadly correlated but also show intriguing temporal discontinuities as at the initiation of plio pleistocene ice ages when a major sea level drop lagged a sharp temperature decline by several hundred thousand years

response to the comment by w h schwarz et al on joint determination of 40k decay constants and 40ar 40k for the fish canyon sanidine standard and improved accuracy for 40ar 39ar geochronology by p r renne et al 2010

late stage slip history of the buckskin rawhide detachment fault and temporal evolution of the lincoln ranch supradetachment basin new constraints from the middle miocene sandtrap conglomerate

a new age within mis 7 for the homo neanderthalensis of saccopastore in the glacio eustatically forced sedimentary successions of the aniene river valley rome abstract field observations as well as borehole sedimentological and geochronologic data allow us to reconstruct the geologic setting of the aniene river valley in northern rome framing it within the recently recognized picture of temporally constrained glacio eustatically forced aggradational successions of this region the sedimentary successions cropping out in this area include those described in the literature of the early 20th century in saccopastore where two skulls of homo neanderthalensis were recovered based on the geometry elevation and sedimentologic features of the investigated sedimentary deposits the stratigraphic record of saccopastore is correlated with the aggradational succession deposited in response to sea level rise during glacial termination iii at the onset of mis 7 i e 250 ka corresponding to the local vitinia formation as opposed to previous correlation with the mis 5 interglacial and a locally defined tyrrhenian stage 130 ka this previous attribution was based on the interpretation of the sedimentary succession of saccopastore occurring between 15 and 21 m a s l as a fluvial terrace formed around 130 ka during the riss wurm interglacial ca 6 m above the present day alluvial plain of the aniene river in contrast to this interpretation a 40ar 39ar age of 129 2 ka determined for this study on a pyroclastic flow deposit intercalated in a fluvial lacustrine sequence forming a terrace 37 m a s l near the coast of rome constrains the aggradational succession in this area to mis 5 precluding the occurrence of an equivalent fluvial terrace at lower elevation in the inland sector of saccopastore we therefore interpret the stratigraphic record of saccopastore as the basal portion of the aggradational succession deposited in response to sea level rise during mis 7 whose equivalent fluvial terrace occurs around 55 m a s l in this region we also review the published paleontological and paleoethnological records recovered in saccopastore and demonstrate their compatibility with the faunal assemblages and lithic industries occurring in the sedimentary deposits of the vitinia formation while we show the lack of any unequivocal late pleistocene mis 5 affinity we therefore propose that the chronostratigraphic position of the saccopastore deposits containing the two skulls should be around 250 000 years as opposed to a previously preferred age of 130 000 years the revised age makes these skulls the oldest italian occurrences of h neanderthalensis and provides evidence for a substantially coeval appearance and evolutionary path with respect to central northern europe

a 90 000 200 000 yrs marine tephra record of italian volcanic activity in the central mediterranean sea abstract a detailed tephrochronological study was undertaken in three deep sea cores collected in the tyrrhenian and ionian seas the age and the origin of the marine tephra were inferred from oxygen isotope records of foraminifera and from major element compositions of glass shards seventy one eruptions were detected in the time interval 90 000 200 000 yrs during which the volcanoes of the roman and campanian regions and of the southern italy were in activity this is attested by the consistency of the geochemical compositions of both marine and terrestrial deposits most of the marine tephra consisted in trachytes and phonolites characterizing a roman and campanian origin several tephra were proposed as key horizons for proximal and distal sediments among them one tephra originating from mount etna 149 300 yrs and five tephra from pantelleria island 130 000 yrs 163 600 yrs 192 500 yrs 197 400 yrs and 198 400 yrs were northerly dispersed several other key horizons originated from the campanian or roman provinces were detected as far as 1000 km from the vents

tephrochronology of the astronomically tuned kc01b deep sea core ionian sea insights into the explosive activity of the central mediterranean area during the last 200 ka abstract we present a major trace and rare earth element characterization of single glass shards from fifteen tephra layers found in the astronomically tuned kc01b deep sea core ionian sea central mediterranean 36 15 25 n 17 34 44 e 3642 m water depth kc01b is considered a reference core for the mediterranean area since it provides a new reliable astronomical tuned timescale for the last 1 112 my lourens 2004 the studied deposits punctuate the marine record in a time span ranging from ca 16 ka to ca 191 ka b p encompassing the climatic zones y x w and v they are related to volcanic activity of the campania plain aeolian islands mt etna and pantelleria island along with major main markers of the central mediterranean area such as y 1 y 5 and x 6 astronomically dated at 16 7 ka 39 1 ka and 110 5 ka respectively the succession contains a number of well preserved deposits which can represent useful inter archive instruments of correlation the campania plain in particular sourced at least nine compositionally homogeneous tephra layers prior to the campanian ignimbrite event the data obtained in this work provide a new detailed analytical reference database for ionian sea tephrochronology and for proximal distal correlation studies they may help to unravel from the marine record the history of poorly known or unknown explosive activity on land since the middle pleistocene along with chemical composition size and dispersal of the products

reassessing the sedimentary deposits and vertebrate assemblages from ponte galeria area rome central italy an archive for the middle pleistocene faunas of europe abstract the ponte galeria area is part of the larger campagna romana and hosted the inner delta of the tiber river since the beginning of the middle pleistocene allowing the deposition of a series of glacio eustatically controlled fluvial lacustrine sedimentary successions very rich in fossil mammal remains due to its richness of fossiliferous sites this area represents an exceptional archive for the study and understanding of the biochronological paleobiogeographical and paleoenvironmental evolution during the middle pleistocene in europe a series of recent studies using the 40 ar 39 ar ages of tephra intercalated within the sedimentary deposits provided a large amount of geochronological data linking these aggradational successions to the different marine isotopic stages in the present paper we present a complete review of the faunal assemblages identified so far in the ponte galeria area and we constrain the ages of the faunal units by placing them within the new chronostratigraphic scheme by means of this interdisciplinary approach we re calibrate the mammal assemblages collected in this area and reconstruct a new biochronological and paleobiogeographic framework for the italian peninsula during the middle pleistocene in particular we distinguish six well defined biochronological units slivia ponte galeria isernia fontana ranuccio torre in pietra and vitinia in the studied area covering a time span of ca 0 6 myr from the early to middle pleistocene transition to at least marine isotope stage 7 this period is characterized in europe by the mid pleistocene revolution global climate change and by the transition at first between villafranchian and galerian taxa and later between the galerian and aurelian ones according to the reviewed data the persistence of villafranchian taxa is recorded in italy at the beginning of the middle pleistocene probably due to favorable climatic conditions or delay in dispersal of competitive species while the faunal turnover between the villafranchian and galerian species was completed around 0 6 0 5 ma during this time bos primigenius and other temperate warm taxa were widespread in the peninsula earlier than in western europe in contrast typical aurelian taxa usually related with temperate cold climatic conditions ursus spelaeus megaloceros giganteus occurred later in italy than in other western european areas