the application of geochemical methods in earthquake prediction in china several geochemical anomalies were observed before the haichen longling tangshan and songpan earthquakes and their strong aftershocks they included changes in groundwater radon levels chemical composition of the groundwater concentration of ca mg cl so4 and hco3 ions conductivity and dissolved gases such as h2 co2 etc in addition anomalous changes in water color and quality were observed before these large earthquakes before some events gases escaped from the surface and there were reports of ground odors being smelled by local residents the large amount of radon data can be grouped into long term and short term anomalies the long term anomalies have a radon emission build up time of from a few months to more than a year the short term anomalies have durations from a few hours or less to a few months

assessing the reliability of magnesium in foraminiferal calcite as a proxy for water mass temperatures though many studies on the mg contents in the calcitic tests of foraminifers exist the processes controlling its uptake are still a matter of debate laboratory cultures offer an excellent opportunity to reveal these mechanisms the mg concentrations within single chambers of the planktic foraminifer globigerinoides sacculifer brady maintained under controlled laboratory conditions were measured 1 at variable temperatures 19 5 29 5 c and constant salinity and 2 at variable salinity 22 45 and constant temperature the experimental results suggest that under natural conditions temperature is the leading mechanism controlling the mg ca ratio temperature and magnesium are related proportionally a temperature increase of ca 10 c gives rise to an increase of the magnesium concentrations of ca 130 drastic unnatural salinity changes dominate the effects of temperature a 110 change in the mg ca ratio was observed when salinity was elevated or reduced by more than ca 10 specimens which underwent gametogenesis reveal significantly higher mg concentrations than specimens that did not release gametes partition coefficients for mg in foraminiferal calcite are orders of magnitude lower than values from inorganically precipitated calcite when comparing observed mg ca ratios of foraminiferal tests with predicted mg ca ratios calculated according to empirical equations it becomes evident that foraminiferal tests are undersaturated with respect to mg for the water temperature they have experienced apparently foraminifers are capable of controlling their mg concentration the physiological processes presumably responsible for such depressed mg ca ratios appear to be temperature controlled as deduced from the close relationship of the observed mg ca ratios and water temperature this study demonstrates that variations in temperature and salinity are definitely reflected in the mg content of foraminiferal tests magnesium may thus serve as a paleo proxy for past surface water temperatures as long as postdepositional changes and salinity variations are of subordinate importance or can be excluded

driving mechanism of tectonic activity in the northern apennines quantitative insights from numerical modeling 1 it is shown by numerical modeling that the recent deformation pattern observed in the northern apennines mainly characterized by progressive eastward migration and bowing of the belt thrusting activity along its external front and tensional tectonics in the internal area can be reproduced at a first approximation by applying a belt parallel se nw compression to the chain which is simulated as a structural system characterized by a high mechanical strength and decoupled from the surrounding zones the above compressional regime obtained by imposing kinematic boundary conditions to the model causes the outward escape of crustal wedges from the chain in particular the northeastward displacement of the romagna marche umbria units and the counterclockwise rotation and northwestward displacement of the ligurian units this kinematics produces compressional to transcompressional strain along the external front of the chain and tensional to transtensional strain in the internal area in line with the observed features that concern both strain style and orientation of principal strains evidence and arguments supporting the kinematic boundary conditions and the model parameterization adopted in modeling are discussed numerical experiments have also been carried out to evaluate the influence of major features of the model parameterization and boundary conditions we have adopted in modeling and to provide insights into the possible influence of strong decoupling earthquakes in the central apennines on tectonic and seismic activity in the northern apennines

modern and pleistocene boron isotope composition of the benthic foraminifer cibicidoides wuellerstorfi abstract here we present the first species specific study of boron isotopes in the epibenthic foraminifer species cibicidoides wuellerstorfi coretop samples from a water depth profile from 1000 to 4500 m on the northern flank of the walvis ridge are 4 4 lower than the values expected based on calculations of the 11bborate of ambient seawater similar values for this foraminifer species are presented from odp site 668b at the sierra leone rise in the equatorial atlantic the consistency between data of the same species suggests the offsets are primary rather than diagenetic glacial c wuellerstorfi from odp 668b and walvis ridge have boron isotope compositions only slightly different to interglacial samples that is no larger than 0 10 ph units or 23 mol kg 1 in co32 above the reconstructed glacial lysocline and 0 07 ph units or 14 mol kg 1 in co32 below we use these results to suggest that glacial deep water ph in the atlantic was similar to interglacial ph the new data resolve the inconsistency between the previously reported high bottom water ph and the lack of significant carbonate preservation of the glacial deep ocean

empirical relationship between ph and the boron isotopic composition of globigerinoides sacculifer implications for the boron isotope paleo ph proxy culture experiments were carried out with the planktonic foraminifera globigerinoides sacculifer at three different ph values 7 6 0 05 8 20 0 05 8 60 0 05 in order to establish the ph dependence of the boron isotopic fractionation between the calcitic tests of g sacculifer and seawater additional objectives were to compare the ph dependences of boron isotopic composition of g sacculifer with that of orbulina universa and inorganic calcite in order to evaluate the robustness of the boron isotope paleo ph proxy the relationship between the boron isotopic composition of g sacculifer and the culture water ph shows heavier boron isotopic values at higher ph this empirical relationship is similar but slightly offset by 3 per mil from that of o universa indicating the presence of biogenic influence vital effect on the boron isotopic composition of foraminifera however comparison of the boron isotopic composition of o universa and g sacculifer with that of inorganic calcite grown over a common ph range shows that inorganic processes are the dominant control on the boron isotopic composition of foraminifera and the vital effects play a small but not insignificant role the results imply that in spite of a small biogenic influence the variation in boron isotopic composition of foraminiferal shells with ph at least for o universa and g sacculifer is consistent with that for inorganic calcite demonstrating the potential of this isotopic signature in foraminifera as a reliable paleo ph proxy

the cause of carbon isotope minimum events on glacial terminations the occurrence of carbon isotope minima at the beginning of glacial terminations is a common feature of planktic foraminifera carbon isotopic records from the indo pacific sub antarctic and south atlantic we use the 13 c record of a thermocline dwelling foraminifera neogloboquadrina dutertrei and surface temperature estimates from the eastern equatorial pacific to demonstrate that the onset of 13 c minimum events and the initiation of southern ocean warming occurred simultaneously timing agreement between the marine record and the 13 c minimum in an antarctic atmospheric record suggests that the deglacial events were a response to the breakdown of surface water stratification renewed circumpolar deep water upwelling and advection of low 13 c waters to the convergence zone at the sub antarctic front on the basis of age agreement between the absolute 13 c minimum in surface records and the shift from low to high 13 c in the deep south atlantic we suggest that the 13 c rise that marks the end of the carbon isotope minima was due to the resumption of north atlantic deep water influence in the southern ocean

origin and coseismic behavior of mineral spring gas at byakko japan studied by automated gas chromatographic analyses abstract the origin and coseismic behavior of mineral spring gas were examined on the basis of continual monitoring data for several gas species the automatic monitoring system used in this study consists of two gas chromatographs and a personal computer several gas species can simultaneously be analyzed with these analyzers the system was so stable and sensitive that minute coseismic anomalies in these species could be detected a positive correlation between n 2 ar and ch 4 ar implies that the mineral spring gas is a mixture of atmospheric air and lithospheric gas the lithospheric gas is mainly composed of n 2 and ch 4 and also contains trace amounts of he it is inferred from isotopic data that lithospheric n 2 and ch 4 are thermogenic and he is mostly radiogenic in contrast o 2 and h 2 in trace amounts show large diurnal fluctuations suggesting that these species should be mostly biogenic ten earthquakes felt around the station occurred during the monitoring period and four of them coincided with coseismic anomalies in the he ar ratio the anomalies may be interpreted as follows by the ground motion at these felt quakes he accumulated in the ground was additionally released into the spring water the continual monitoring of these gas species enables us to discuss in detail the origin and behavior of the spring gas and to evaluate background noise of the data

intraplate deformation and basin formation during the tertiary within the northern iberian plate origin and evolution of the almazan basin the tertiary almazan basin was a topographic high during the mesozoic rifting at the northern part of the iberian plate it was bordered by two mesozoic basins 1 the castilian basin with a maximum thickness of more than 2000 m to the south and 2 the cameros basin with a maximum thickness of 9000 m to the north to the east the almazan basin is bordered by paleozoic rocks of the nw se trending aragonian range which underwent little subsidence during the mesozoic the two mesozoic basins show an e w direction during the tertiary nne ssw compression mainly late eocene early miocene both mesozoic basins were inverted and uplifted and the almazan basin with an overall synclinal geometry was filled with syn tectonic terrestrial sediments reaching a maximum thickness of 3500 m deformation during the tertiary was strongly controlled by preexisting structures both mesozoic extensional faults and reactivated variscan folds the depocenter of the tertiary basin migrated southward during the paleogene this migration is consistent with a piggyback transport of the whole basin northward due to the movement on the underlying crustal scale north verging cameros thrust the geometry and sedimentary evolution of the almazan thick skinned piggyback basin was controlled by the uplift associated with the main crustal scale thrust which was the main source area and was separated from the foreland basin since the early stages of filling late eocene this makes the main difference with thin skinned piggyback basins controlled by the foreland thrust belt and separated from the foreland basin only at their late stages

oceanic ph control on the boron isotopic composition of foraminifera evidence from culture experiments culture experiments were carried out with the species orbulina universa at four different ph values 7 70 0 05 8 15 0 05 8 60 0 05 and 9 00 0 10 in order to establish the ph dependence of boron isotope fractionation between seawater and foraminifera a clear relationship between the boron isotopic composition of the foraminifera and the ph of the seawater culture solutions was found showing heavier boron isotopic composition at higher ph this finding supports the viability of boron isotopes as a paleo ph tool it is important to note that orbulina universa cultured in natural seawater as well as those obtained from coretop samples have a significantly lighter boron isotopic ratio than globigerinoides sacculifer from coretop samples suggesting that at least for this species a vital effect is active

monitoring of hydrogen along the san andreas and calaveras faults in central california in 1980 1984 hydrogen h2 has been monitored continuously at 1 5 m depth at nine sites along the san andreas and calaveras faults in central california since december 1980 site characteristic small noninstrumental diurnal variations were recorded during quiescent periods at most sites abrupt h2 changes were observed concurrently at two sites on the calaveras fault some of these were correlated with oscillatory fault slips large 1000 4000 ppm h2 increases were recorded at some sites on the san andreas fault between july 1982 and november 1983 which may be correlated with eleven m 5 earthquakes that occurred near coalinga during this period we attribute both the h2 increases and the triggering of the earthquakes to a large scale compressive stress field within the ductile mafic crust near the plate boundary the stress perhaps caused bulging of the base of the brittle upper crust and thus caused dilation of the san andreas fault zone allowing the escape of pent up h2 generated by hydration reaction of the mafic crust at the same time mobile serpentinites may have squeezed into the seismogenic fault beneath the coalinga area triggering the earthquakes

magma emplacement in a thrust ramp anticline the gavorrano granite northern apennines italy 1 magma emplacement in the upper crust is often associated with crustal extension whereby space for intrusions is made by dilation along transtensive and strike slip faults the lenticular shape of several intrusions indicates that a further mechanism for magma intrusion is laccolith emplacement with roof uplift of the overburden additionally melts exploit rheological discontinuities e g sedimentary layering during their ascent we present an emplacement model for intrusion of the shallow level gavorrano granite northern apennine italy which is located at the core of an open anticline the shape of the intrusion and structural features of the host rocks are indicative of a synkinematic emplacement in a growing thrust anticline space was provided by the opening of dilatation zones at the core of anticline as a consequence of different amounts of translation between hanging wall and footwall units which were separated by evaporitic rocks these evaporitic units acted as major decollement layers analog models provide results in good agreement with the structural setting of the anticline and emphasize the possibility that melts filled the dilatation zone with the decollement layers further facilitating intrusion

stable oxygen isotope composition is biased by shell calcification intensity in planktonic foraminifera planktonic foraminifera are widely used for environmental reconstructions through measurements of their shell s geochemical characteristics including its stable oxygen and carbon isotope composition using these parameters as unbiased proxies requires a firm knowledge of all potential confounding factors influencing foraminiferal shell geochemistry one such parameter is the shell calcification intensity shell weight normalized for shell size that may influence the shell delta 18o value either bioenergetically by reducing energy available and required for equilibrium isotope fractionation during faster calcification or kinetically by influencing calcification depth through the shell s density contrast with seawater specimens from the globigerinoides ruber elongatus compound from a sediment trap in the north atlantic have been used to quantify the influence of shell calcification intensity on shell delta 18o values shell calcification intensity was found to have a significant effect on the shell stable oxygen isotope composition in all species through model fitting it is suggested that the effect size may be in a range of 1 to 2 depending on species depth migration and local oceanographic conditions we show that the confounding effect of shell calcification intensity on stable oxygen isotope composition can be of importance depending on the anticipated precision of the derived reconstructions a framework is provided to quantify this effect in future studies

seawater ph control on the boron isotopic composition of calcite evidence from inorganic calcite precipitation experiments experiments involving boron co precipitation with calcite have been carried out inorganically under controlled ph conditions 7 9 0 05 8 3 0 05 and 8 6 0 05 to determine the dependence of the boron isotopic composition 11b of calcite on the ph of seawater another purpose of these experiments was to estimate the magnitude of the biogenic influence on the 11b value of foraminifera by comparing their boron isotopic composition with that of the inorganic calcite over a common ph range the results show a clear relationship between 11b of inorganic calcite and the ph of artificial seawater the variation of boron isotopic fractionation between seawater and calcite with ph estimated from these experiments is similar to that estimated for cultured o universa and the theoretically predicted trend the results also support the hypothesis that b oh 4 is the dominant species incorporated into the calcite structure however the boron isotopic fractionation between seawater and inorganic calcite is lower than that estimated for o universa indicating the presence of a biogenic effect on the boron isotopic composition at least of this species of foraminifera most importantly the results imply that in spite of a small biogenic influence on the boron isotopic composition of foraminifera the variation in 11b of foraminiferal shells with ph at least for o universa is comparable to that for inorganic calcite supporting the potential of this isotopic signature in foraminifera as a reliable paleo ph proxy

biomineralization in perforate foraminifera in this paper we review the current understanding of biomineralization in perforate foraminifera ideas on the mechanisms responsible for the flux of ca2 and inorganic carbon from seawater into the test were originally based on light and electron microscopic observations of calcifying foraminifera from the 1980s onward tracer experiments fluorescent microscopy and high resolution test geochemical analysis have added to existing calcification models despite recent insights no general consensus on the physiological basis of foraminiferal biomineralization exists current models include seawater vacuolization transmembrane ion transport involvement of organic matrices and or ph regulation although the magnitude of these controls remain to be quantified disagreement between currently available models may be caused by the use of different foraminiferal species as subject for biomineralization experiments and or lack of a more systematic approach to study dis similarities between taxa in order to understand foraminiferal controls on element incorporation and isotope fractionation and thereby improve the value of foraminifera as paleoceanographic proxies it is necessary to identify key processes in foraminiferal biomineralization and formulate hypotheses regarding the involved physiological pathways to provide directions for future research

isotopic record of pleistocene glacial interglacial cycles in pelagic carbonates revisiting historical data from the caribbean sea the glacial interglacial cycles of the pleistocene were first recognised by variations in the oxygen isotopic composition of planktonic foraminifera from cores in the caribbean sea since this pioneering work by emiliani this proxy has been extensively applied to a variety of carbonate biominerals over the entirety of the meso cenozoic however palaeoceanographic studies have overwhelmingly focused on foraminifera compared to other calcifying microorganism fossils such as the coccoliths in this study i revisit coccolith stable isotopic data obtained from the classic p6304 4 core in light of recent developments in the biogeochemistry of coccolithophores in particular i show that the coccolith stable isotope record of the last 13 marine isotope stages 480 kyrs is significantly biased by large vital effects the magnitude of coccolith carbon and oxygen isotope vital effects is not uniform but shows remarkable co variance with the vostok co2 ice record during periods of relatively elevated co2 interstadials the expression of the vital effect is relatively small whereas it can as high as 3 for the oxygen isotopes during glacial stadials which i argue is a result of enhanced co2 limitation of coccolithophores using this paradigm i propose that coccolithophore vital effects are not a complicating factor but rather the signal of interest as the magnitude of the coccolith vital effect is shown to scale with pco2 coccolith carbon and oxygen isotopes may be used in conjunction with foraminifera data to reconstruct and refine aqueous co2 concentrations in the past

a multiple proxy and model study of cretaceous upper ocean temperatures and atmospheric co2 concentrations foraminiferal d 18 o and mg ca suggests that the ratio of magnesium to calcium in the turonian coniacian ocean may have been lower than in the albian cenomanian ocean perhaps coincident with an ocean 87 sr 86 sr minimum the carbon isotopic compositions of distinct marine algal biomarkers were measured in the same sediment samples the d 13 c values of phytane combined with foraminiferal d 13 c and inferred temperatures were used to estimate atmospheric carbon dioxide concentrations through this interval estimates of atmospheric co2 concentrations range between 600 and 2400 ppmv within the uncertainty in the various proxies there is only a weak overall correspondence between higher lower tropical temperatures and more less atmospheric co2 the genesis climate model underpredicts tropical atlantic temperatures inferred from odp leg 207 foraminiferal d 18 o and mg ca when we specify approximate co2 concentrations estimated from the biomarker isotopes in the same samples possible errors in the temperature and co2 estimates and possible deficiencies in the model are discussed the potential for and effects of substantially higher atmospheric methane during cretaceous anoxic events perhaps derived from high fluxes from the oxygen minimum zone are considered in light of recent work that shows a quadratic relation between increased methane flux and atmospheric ch4 concentrations with 50 ppm ch4 genesis sea surface temperatures approximate the minimum upper ocean temperatures inferred from proxy data when co2 concentrations specified to the model are near those inferred using the phytane d 13 c proxy however atmospheric co2 concentrations of 3500 ppm or more are still required in the model in order to reproduce inferred maximum temperatures

tethyan heritage in the development of the neogene umbria marche fold and thrust belt italy a 3d approach the umbria marche fold and thrust belt northern apennines italy provides excellent opportunities to evaluate the structural heritage of the opening of the mesozoic tethys ocean in the 3d geometry of the neogene compressional structures related to the alpine orogeny the structure and evolution of a portion of the southernmost belt between the nera river and the rieti basin are described as a field example and the kinematics along well exposed mesozoic extension structures are provided cross section restoration shows a close coincidence between these extension structures and the neogene thrust ramps thus suggesting that the geometry of the latter was controlled by the map distribution of the former sequential balancing also allows for the definition of the geometrical pattern of pre existing normal faults which were produced in response to a unidirectional or a two directional extension stress field the inferred direction of principal extension corrected for the effects of late deformation is consistent with that proposed for the northern margin of the adria promontory in global scale plate tectonic reconstructions

geochemical precursors to seismic activity studies of earthquake precursory phenomena during the last several decades have found that significant geophysical and geochemical changes can occur prior to intermediate and large earthquakes among the more intensely investigated geochemical phenomena have been 1 changes in the concentrations of dissolved ions and gases in groundwaters and 2 variations in the concentrations of crustal and mantle volatiles in ground gases the concentration changes have typically showed no conanomalies trend either increasing or decreasing and the spatial and temporal distribution of the observed anomalies have been highly variable as a result there is little agreement on the physical or chemical processes responsible for the observed anomalies mechanisms proposed to account for precursory groundwater anomalies include ultrasonic vibration pressure sensitive solubility pore volume collapse fracture induced increases in reactive surfaces and aquifer breaching fluid mixing precursory changes in soil gas composition have been suggested to result from pore volume collapse micro fracture induced exposure of fresh reactive silicate surfaces and breaching of buried gas rich horizons an analysis of the available field and laboratory data suggests that the aquifer breaching fluid mixing ab fm model can best account for many of the reported changes in temperature dissolved ion and dissolved gas concentrations in groundwater ultrasonic vibration and pressure sensitive solubility models cannot reasonably account for the geochemical variations observed and although the pore collapse model could explain some of the observed chemical changes in groundwater and ground gas uncertainties remain regarding its ability to generate anomalies of the magnitude observed other geochemical anomalies in particular those associated with hydrogen and radon seem best accounted for by increases in reactive surface areas irsa model that may accompany precursory deformation around the epicenter of an impending earthquake analysis of the probable response of these models to the earthquake preparation process as well as to other environmental factors suggests that geochemical monitoring programs can provide information that may be valuable in forecasting the probability of an earthquake however because of the complexity of the earthquake preparation process the absolute prediction of seismic events using geochemical methods alone does not presently appear to be feasible

impacts of ph and co32 on the incorporation of zn in foraminiferal calcite the trace elemental composition of foraminiferal shell calcite is known to reflect the environment in which the shell was precipitated whereas conservative elements incorporated in foraminiferal shell carbonate reflect factors such as temperature mg carbonate chemistry b and salinity na the nutrient type elements ba cd and possibly zn are useful tools to reconstruct biogeochemical cycling and past ocean circulation still also nutrient type elements will be most likely influenced by factors other than their relative concentrations culturing benthic foraminifera under controlled carbonate chemistry conditions allows for disentanglement of impacts of different parameters of the carbon system on the elemental composition of foraminiferal calcite here we show that zinc incorporation in cultured specimens of the benthic foraminifer ammonia tepida is correlated to changes in carbonate ion concentration co32 by modeling activities of different chemical species of zn in seawater over a range of co32 we suggest that zn2 rather than other relatively abundant zn species e g znco30 and znhco3 is taken up during biomineralization our results suggest that foraminiferal zn ca might be especially useful when combined with other co32 proxies enabling reconstruction of past seawater element concentrations conversely when the nutrient type element concentrations are known incorporation of zn in foraminiferal shells can be used to reconstruct past sea water carbon speciation

mapping capable faulting hazard in a moderate seismicity high heat flow environment the tuscia province southern tuscany northern latium italy abstract this study is focused on potential evidence of capable faulting affecting southern tuscany northern latium a region of high heat flow and moderate to low seismicity here we refer to this region as tuscia the latin name for the land of the etruscans the review of the evidence for active tectonics in this area has allowed us to identify several potentially active capable faults mapped using a combination of analysis of digital terrain models with remote sensing and local geological information derived from bibliographic data and different scale maps active and capable faulting is certainly more evident in the eastern sector of tuscia chianti cetona ridge pienza amiata and bolsena caldera however even in the western tuscia e g colline metallifere and tyrrhenian coast capable faulting may be hypothesized along numerous structural elements the characterization of active faulting potential in terms of geometry slip types and rates in such a high heat flow environment beyond its usefulness in improving the assessment of fault displacement and earthquake hazard also helps to improve knowledge of the stress field and structural setting of the many geothermal fields in the area this allows new useful insights into geothermal exploitation and hazard e g induced triggered seismicity moreover this new knowledge of active tectonics and capable faults of the hinterland sector of the northern apennines may also provide useful insights into the siting processes of highly hazardous and strategic structures and more generally in land use planning and management of infrastructures especially during emergencies

cover thrust reactivations related to internal basement involvement during neogene quaternary evolution of the northern apennines up to recently the neogene quaternary evolution of the northern apennines italy has been described by the classic model of a migrating eastward compressive external front with an extensional regime in the back areas connected with the tyrrhenian basin formation however in the last few years new structural data have been collected in the internal marine and continental episutural basins and in the external exposed thrust belt a complex structural evolution has now been reconstructed with coeval main tectonic phases that affect both areas with stress field change four main tectonic phases have been identified since late tortonian times these are dated as messinian late pliocene middle and late pleistocene the thrust belt has a complex evolution detected in a wide external area of the chain after the first emplacement of the main thrust sheets with reactivations and out of sequence thrusting these reactivation phases fit very well with the compressive phases affecting the sediments of the internal basins suggesting a direct relationship within a single evolutive model the increased knowledge of the deep structure of the northern apennines through geophysical and subsurface data acquired in the last few years indicates the basement involvement at least for the internal side of the northern apennines this basement involvement also played an important role in the tectonic evolution of the external sector of the apennines in this paper a new model is proposed that integrates field data geophysical evidence and geodynamic constraints the thrust reactivations and the out of sequence structures of the external area are related to internal crustal thrust activity the deformed sediments of the neogene quaternary basins are dating the thrust activity all the evidences point to a late neogene rejuvenation of the tectonic evolution but some inferences can be drawn on the development of the foredeep

the source of ions for biomineralization in foraminifera and their implications for paleoceanographic proxies the global carbon cycle is strongly perturbed by fossil fuel burning leading to atmospheric co2 increase climatic warming followed by polar ice melting and global sea level rise are predicted due to the greenhouse effect of increasing co2 in the atmosphere houghton et al 1995 the ocean plays a major role in neutralizing the excess co2 because the amount of inorganic carbon available for exchange with the atmosphere in the ocean is approximately 50 60 times larger than in the atmosphere e g siegenthaler and sarmiento 1993 the bulk of the atmospheric co2 excess will eventually be neutralized by caco3 dissolution in the deep marine environment this is however is a relatively slow process that operates on the time scale of ocean circulation 1000 yrs and is therefore causing an accumulation of co2 in the atmosphere this phenomenon will result in potentially severe consequences to the well being of global ecological systems obviously the scientific attention of many biogeochemists is focused on processes controlling the response of the marine system to changes in atmospheric co2 concentrations e g archer and maier reimer 1994 broecker 1997 sigman and boyle 2000 berger 2002 foraminifera corals and coccolithophores in the global carbon cycle there are four dominant processes involved in neutralizing the excess atmospheric co2 in the ocean these are 1 gas exchange at the air sea interface and reaction with the carbonate ion to form bicarbonate 2 net primary productivity 3 caco3 production and dissolution and 4 ocean circulation most of these processes are biologically mediated and may have special importance in shallow tropical environments where the exchange with the atmosphere is more direct in this review we address the mechanism of biomineralization in one of the major groups that precipitates caco3 in the ocean the foraminifera as we will show this group

experimental studies of the mechanisms of seismo geochemical precursors the following aspects of modeling experiments on seismo geochemical precursors are described 1 gas emission during laboratory stress loading and rupture of rocks 2 field measurements with explosion sources 3 aquifer mixing tests in the field 4 experimental studies of physico chemical processes caused by stress events from these studies three conclusions have been drawn 1 long term seismo geochemical anomalies appear to be related to the stage of elastic deformation of rocks under stress loading prior to a seismic event short term anomalies appear to be related to the plastic deformation of rock and spike like anomalies appear to be related to shear displacement before an earthquake 2 anomalous changes in chemical composition of groundwater and the escape of gases from the ground appear to result from rock fracturing which opens up pathways for the upward migration of water from deep confined aquifers and for the upward migration of gases from the deeper crust 3 chemical reactions induced by increasing stress in the epicentral region may result in the anomalous changes in chemical composition of groundwater observed before some large earthquakes

modulation and daily banding of mg ca in orbulina universa tests by symbiont photosynthesis and respiration a complication for seawater thermometry the mg ca composition of calcium carbonate tests shells secreted by planktonic foraminifera is increasingly being employed to estimate past seawater temperatures and reconstruct paleocean and climate records spanning hundreds of thousands of years we show using two high resolution microanalysis techniques that the final chamber of the planktonic foraminifera orbulina universa typically comprises between three and six paired low and high mg growth bands the number and spacing of these bands is consistent with a diurnal origin modulated by changing ph within the foraminiferal microenvironment due to the day night photosynthesis respiration cycle of algal symbionts the amplitude of mg ca variation within individual tests and across many daily growth bands cannot be accounted for by seawater temperature in the shallow euphotic zone habitat of o universa our results indicate the mg ca composition of calcite precipitated by o universa in nature is strongly influenced by diurnal changes in the biological activity of algal symbionts and the host foraminifer this brings into question the fundamental premise often made in applying mg ca palaeoseawater thermometry that the mg ca composition of foraminiferal calcite is determined by seawater temperature and whether the mg ca composition of other planktonic species that are more widely used for palaeoseawater thermometry are subject to similar influences 2004 elsevier b v all rights reserved

the sequence of events surrounding termination ii and their implications for the cause of glacial interglacial co2 changes events surrounding termination ii as preserved in the vostok ice core provide a number of clues about the mechanisms controlling glacial to interglacial climate change antarctic temperature and the atmosphere s co2 content increased together over a period of 8000 years this increase is bounded by a drop in dust flux at its onset and by a drop in the 18o of trapped air at its finish a similar lag between dust flux and foraminiferal 18o is seen in a southern ocean marine record suggesting that the 18o in air trapped in vostok ice is a valid proxy for ice volume the synchronous change of atmospheric co2 and southern hemisphere temperature thus preceded the melting of the northern hemisphere ice sheets this observation coupled with the fact that nutrient reorganization in the north atlantic occurs with or after the sea level rise eliminates many scenarios proposed to explain the co2 rise including those which rely on sea level change conveyor related nutrient redistribution or north atlantic cooling southern ocean scenarios become the front runners but the most popular mechanism iron fertilization has two problems in explaining the co2 rise before termination ii first much of the dust demise occurs prior to the change in co2 so if iron is the villain a threshold value of its supply must be called upon above which productivity does not continue to increase second the co2 rise continues for some 4 5 kyr after the dust flux has fallen to close to zero these problems may be solved if the increased iron supply in dust caused higher rates of nitrogen fixation during the glacial periods in this case the residence time of oceanic nitrate of a few thousand years would enable decreasing productivity to be a global rather than a local phenomenon and would explain the slow rampup of atmospheric co2

kinematic evolution of thrust related structures in the umbro romagnan parautochthon northern apennines italy in the internal part of the umbro marchean romagnan apennines the foredeep clastic wedge constituting the neogene part of the sedimentary cover is completely detached from the underlying mesozoic palaeogene succession the resulting umbro romagnan parautochthon consists of tectonostratigraphic units with a general geometry of broad synclinal blocks separated by narrow faulted anticlines thrust related structures observed in the field require thrust ramp propagation to have occurred within already folded rocks therefore they cannot be restored using simple fault bend fold or fault propagation folding models evidence for a passive fold origin in the studied rocks suggests that an early detachment folding episode preceded ramp propagation the latter was facilitated by the enhanced thickness of incompetent material in the cores of detachment anticlines which became the preferential sites where thrust ramps cut up section depending on the trajectory of such thrust ramps different types of fault related structures could develop hanging wall anticlines which give way to monoclinal structures higher up in the section are associated with listric thrust ramps whereas hanging wall monoclines approximately parallel to the underlying fault surface are associated with straight trajectory ramps this kinematic evolution which occurred partly during syn depositional compression also accounts for the observed lithofacies distribution the latter reflects an early differentiation of the foredeep trough into sub basins that are progressively younger towards the foreland the detachment anticlines that originally bounded such sub basins were the site of later thrust propagation leading to a tectonic juxtaposition of different tectonostratigraphic units consisting of broad nw se elongate synclinal blocks

a comparative study of the northwest africa and eastern equatorial pacific upwelling zones as sources of co2 during glacial periods based on boron isotope paleo ph estimation paleo ph reconstructions based on boron isotopic composition of foraminifera have been used to estimate glacial interglacial changes in surface ocean pco2 of the northwest african upwelling zone on comparison with a similar study for the eastern equatorial pacific upwelling zone it can be concluded that the two major upwelling zones acted quite differently during the glacial periods as compared to today while the ph of the surface ocean off northwest africa was 0 2 0 07 units higher during the glacial period compared to that during holocene there was no significant glacial interglacial change in the surface ocean ph in the eastern equatorial pacific carbonate chemistry reconstructions based on the estimated ph changes suggest that the ocean atmosphere pco2 gradient off northwest africa was lower by at least 70 40 atm during glacial periods compared to during the holocene in contrast the ocean atmosphere pco2 gradient in the eastern equatorial pacific was higher by at least 80 40 atm during glacial periods as compared to during the holocene hence the eastern equatorial pacific upwelling system was a significantly larger source of co2 to the atmosphere while the one off northwest africa was a significantly smaller source of co2 during the last glacial period the pco2 reconstructions further indicate that in spite of higher glacial productivity compared to during the holocene neither of the two areas became a sink of co2

preliminary results of seismogeochemical research in china several kinds of geochemical anomaly before strong earthquakes have been observed in china since 1966 they include changes in groundwater radon levels ion content of water ca 2 mg 2 cl so4 2 f dissolved gases h2 co2 and gases escaping from the aeration zone through abandoned dry wells ar n2 co2 the radon anomalies may be grouped as long term and short term anomalies most of the geochemical anomalies observed are characterized by a pattern of increase the largest amplitude recorded was 37 times the base level preliminary study indicates that the types of seismogeochemical anomaly observed prior to strong earthquakes depend on tectonic geologic lithologic and hydrogeological conditions at the monitoring station results obtained from modelling experiments on the mechanisms of some anomalies are given

bowl shaped basin related to low angle detachment during continental extension the case of the controversial neogene siena basin central italy northern apennines abstract this paper deals with the tectonic evolution of a bowl shaped neogene basin siena basin located in the inner northern apennines and developed during an articulated tectonic evolution this basin was controversially interpreted by different authors as graben half graben or thrust top basin structural and stratigraphic data from the basin substratum and filling sediments integrated with the interpretation of reflection seismic profiles and borehole logs highlight that the siena basin consists of a tectonic depression with a complex internal architecture such a basin developed on a multilayered substratum deeply affected by extensional tectonics since the middle miocene extensional detachments produced a widespread thinning of the basin substratum and superimposed on contractional structures developed during the northern apennines collisional events extensional detachments accommodated within weak horizons and gave rise to the lateral segmentation of most competent stratigraphic horizons sediments filling the siena basin mainly deposited on the ligurian units the topmost tectonic units forming the tectonic pile in the gap between two laterally segmented geological bodies made up of the triassic siliciclastic succession of the verrucano group such a lateral segmentation produced a synformal structural depression not delimited by faults filled by late serravallian late messinian marine to continental sediments which deposited during the extensional faulting from the latest early pliocene to the middle pliocene the architecture of the basin was modified by an high angle normal fault system which affected the eastern side of the basin and produced new accommodation space for marine sediments in sum the siena basin consists of a sin tectonic basin developed on the hanging wall of staircase extensional detachments later affected by high angle normal to oblique faults the latter faults defined a half graben during the latest evolution of the basin the tectonic evolution of the siena basin made it possible to point out some differences with respect to the types of bowl shaped basins related to extensional detachments and named as supradetachment basins

sea level and deep water temperature changes derived from benthic foraminifera isotopic records we show that robust regressions can be established between relative sea level rsl data and benthic foraminifera oxygen isotopic ratios from the north atlantic and equatorial pacific ocean over the last climatic cycle we then apply these regressions to long benthic isotopic records retrieved at one north atlantic and one equatorial pacific site to build a composite rsl curve as well as the associated confidence interval over the last four climatic cycles our proposed reconstruction of rsl is in good agreement with the sparse rsl data available prior to the last climatic cycle we compute bottom water temperature changes at the two sites and at one southern indian ocean site taking into account potential variations in north atlantic local deep water 18o our results indicate that a last glacial maximum lgm enrichment of the ocean mean oxygen isotopic ratio of 0 95 is the lowest value compatible with unfrozen deep waters in the southern indian ocean if local deep water 18o did not increase during glacials with respect to present such a value of the lgm mean ocean isotopic enrichment would impose a maximum decrease in local bottom water 18o at the north atlantic site of 0 30 during glacials

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

extension and compression in the northern apennines italy hinterland evidence from the late miocene pliocene siena radicofani basin and relations with basement structures 1 the northern apennines na hinterland area is characterized by a complex neogene quaternary tectonics where both crustal extension associated with the tyrrhenian basin opening and crustal shortening in the onshore area took part in the deformation analysis of synorogenic deposits preserved in the nnw trending siena radicofani basin srb extending along a large part of the na hinterland documents the evolution of deformation of this sector during the last 9 ma information from subsurface geology deep seismic lines commercial seismic lines and deep wells surface geology mapping and structural analysis and from analogue modeling was integrated and used to infer the tectono sedimentary history of the srb and its relation with structures in the substratum as well as the possible implications for the evolution of the na hinterland the results we obtain indicate that the srb and the adjoining hinterland basins were bounded by thrust anticlines controlling basin development and deformation seismic lines across the srb display various examples of compressional structures affecting the basin fill and the substratum such as thrust anticlines and reverse faults notably these basin scale structures exhibit a good correlation with those observed in the field and are consistent with the kinematics of the outcrop scale compressional structures the thrust anticlines bounding the basins are often cored by triassic evaporites burano formation suggesting that this weak layer decoupling the sedimentary cover from the underlying crystalline basement controlled their evolution in this circumstance three series of scaled brittle ductile physical models have been used to investigate the development of a basement cover system with a decollement ductile layer at the base of the sedimentary cover these models simulate the evolution of the northern apennines hinterland where the basement is involved in the thrusting and the sedimentary cover is shortened above a basal ductile layer given by the burano formation longitudinal models cross sections display similar deformation patterns to those observed in the na hinterland such as characteristic wavelength of both basement and cover structures as well as detachment and fault propagation folding in the cover extensional tectonics is instead found to control sedimentation in the southern part of the srb at 8 ma or representing recent deformation the older extensional event is here related to the forelandward propagation of tyrrhenian related extension that could reactivate suitably oriented basement thrusts transfer zones produced a differential propagation of extension such that along strike sectors of the hinterland were eventually deformed by different stress fields analysis of the srb and of other adjoining basins reveals that the na hinterland experienced alternated periods of forward and backward migration of the compression extension transition in our interpretation the competition between extension and compression in the hinterland is related to the nnw directed africa pelagian indentation responsible for the lateral extrusion of the na and the contemporaneous opening of the tyrrhenian basin in the inner zone increased marginal loading at the foreland promoting reactivation of hinterland thrusts may have influenced this process as well

orbitally driven climate forcing in late pliocene lacustrine siderite rich clastic rhythms upper valdarno basin northern apennines italy abstract distinctive siderite rich lacustrine strata are exposed along the western margin of the upper valdarno basin northern apennines italy these late pliocene deposits belong to the castelnuovo synthem which is the oldest unconformity bounded stratigraphic unit of the basin fill facies analyses were performed on a paleomagnetically calibrated log depicting two palustrine to lacustrine systems separated by a short lived fluvial phase the lacustrine deposits are structured in rhythms and composed of lower clastic and upper siderite enriched beds the rhythmic stacking pattern has been analysed and subjected to a cyclostratigraphic analysis similar trends between a local facies derived base level curve and global isotopic stacks suggest climate forcing which is confirmed by the straightforward tuning of the lacustrine rhythms to precession related insolation phases clastic deposition has been linked to colder and drier phases involving vegetation retreat and enhanced sediment production and transport prevalent chemical deposition siderite instead occurs during hot and wet phases and is characterised by vegetation blooming and then a generalised reduction in clastic supply this mechanism is probably coupled with lake level fluctuations that are related to variations in the regional hydrological balance the orbital behaviour of the castelnuovo synthem is characterised by major sensitivity to precession but a weaker response to 100 ky eccentricity however eccentricity modulation is marked by a 400 ky minimum which recurs in correspondence with a sub aerial exposure between the two lacustrine bedsets no obliquity related rhythmicity has been recorded the succession investigated here is consistent with other pliocene palustrine to lacustrine circum mediterranean case studies the results have also been compared to a previous cyclostratigraphic framework elaborated from magnetic susceptivity allowing critical comparisons to be made between this latter proxy and the analysis of sedimentary facies cycles

an outer ramp to basin plain transect interacting pelagic and calciturbidite deposition in the eocene oligocene of the tuscan domain adria microplate italy abstract the interaction of ramps basin plains and turbidite systems on the scale of tens of km has been rarely observed in fossil examples deep marine eocene oligocene beds are exposed in the axial zone of the chianti mountains italy and compose a regionally continue stratigraphic succession known as the scaglia toscana formation the formation was deposited in the tuscan domain of the adria microplate this research aims at depicting its depositional architecture and evolution in the type area stratigraphic and sedimentologic analyses were performed on a ca 25 km long transect that includes depositional systems sectioned both in the down and along dip directions shaly carbonate deposits compose a complex of interacting ramps basin plains and turbidite floor fan systems ramp deposits accumulated above the lysocline and in oxic conditions basin plain beds were deposited below the lysocline and were subject to episodes of oxygen depletion turbidity flows fed elongate fan lobes characterized by poor channelisation the basin palaeogeography hampered the development of slope apron turbidite systems the eocene oligocene geodynamic setting of the tuscan domain was characterized by the evolution of a peripheral bulge and by the early structuring of a foredeep basin syn sedimentary tectonism acted a primary role in the basin scale arrangement however other mechanisms also contributed to the local facies distribution including the disposition of sediment source areas and intrabasinal confinement morphologies as well as relative oscillations of the depositional surface with respect to the lysocline and oxycline

isotope paleontology growth and composition of extant calcareous species abstract isotope paleontology uses the isotopic composition of fossil remains of organisms to make inferences about the physical surroundings of growth of the organisms especially temperature and to obtain clues about life history and modes of growth in calcareous fossils oxygen isotopes are mainly used in the former and carbon isotopes in the latter however since physical surroundings and organism response are intimately associated both types of information are contained in each of the isotopic signals to explore the potential of isotope paleontology and to provide a basis for reconstruction a broad range of extant organisms has been studied taking the pioneering work of epstein and associates as a starting point results are summarized for a representative sampling of these studies with emphasis on work at the laboratories of the authors from the mid seventies to the present the organisms considered are nannoplankton benthic algae planktonic and benthic deep sea foraminifera larger foraminifera sponges corals bryozoans polychaetes arthropods bivalves gastropods cephalopods and vertebrates fish otoliths the survey broadly suggests that regarding oxygen isotopes materials tend to be precipitated close to equilibrium with the surrounding seawater as postulated by urey and that for carbon isotopes disequilibrium is the rule life spans growth rates differential seasonal growth and age of reproductive activity can be extracted under favorable circumstances from individual shells and skeletal parts in detail the interpretation of isotope records of individual shells is quite complicated and simple models will fail to give satisfactory results in many or most cases

seawater ph and isotopic paleotemperatures of cretaceous oceans abstract stable oxygen isotope ratios 18 o of foraminifera are widely used to reconstruct the climatic history of earth it is well known that temperature reconstructions based on 18 o are complicated by factors such as the unknown isotopic composition of the ocean in addition recent experimental and theoretical work has shown that the seawater ph has a marked effect on the 18 o of foraminifera here i employ this effect to demonstrate that reconstructions based on 18 o of foraminifera may underestimate sea surface temperatures in the geological past ocean surface temperatures for the mid cretaceous are estimated to have been 2 3 5 c higher than previously thought

vital effects in coccolith calcite cenozoic climate pco2 drove the diversity of carbon acquisition strategies in coccolithophores 1 coccoliths calcite plates produced by the marine phytoplankton coccolithophores have previously shown a large array of carbon and oxygen stable isotope fractionations termed vital effects correlated to cell size and hypothesized to reflect the varying importance of active carbon acquisition strategies culture studies show a reduced range of vital effects between large and small coccolithophores under high co2 consistent with previous observations of a smaller range of interspecific vital effects in paleocene coccoliths we present new fossil data examining coccolithophore vital effects over three key cenozoic intervals reflecting changing climate and atmospheric partial pressure of co2 pco2 oxygen and carbon stable isotopes of size separated coccolith fractions dominated by different species from well preserved paleocene eocene thermal maximum petm 56 ma samples show reduced interspecific differences within the greenhouse boundary conditions of the petm conversely isotope data from the plio pleistocene transition ppt 3 5 2 ma and the last glacial maximum lgm 22 ka show persistent vital effects of 2 ppt and lgm data show a clear positive trend between coccolith cell size and isotopic enrichment in coccolith carbonate as seen in laboratory cultures on geological timescales the degree of expression of vital effects in coccoliths appears to be insensitive topco2 changes over the range 350 ppm pliocene to 180 ppm lgm the modern array of coccolith vital effects arose after the petm but before the late pliocene and may reflect the operation of more diverse carbon acquisition strategies in coccolithophores in response to decreasing cenozoic pco2

fault sourced alluvial fans and their interaction with axial fluvial drainage an example from the plio pleistocene upper valdarno basin tuscany italy abstract the present study deals with the fault sourced alluvial fan deposits of the plio pleistocene upper valdarno basin northern apennines italy different phases of alluvial fan aggradation progradation and backstep are discussed as possible effects of the interaction among fault generated accommodation space sediment supply and discharge variations affecting the axial fluvial drainage the upper valdarno basin located about 35 km se of florence is filled with 550 m palustrine lacustrine and alluvial deposits forming four main unconformity bounded units i e synthems the study alluvial fan deposits belong to the two uppermost synthems montevarchi and torrente ciuffenna synthems and are early to middle pleistocene in age these deposits are sourced from the fault bounded ne margin of the basin and interfinger with axial fluvial deposits alluvial fan deposits of the montevarchi synthem consist of three main intervals i a lower interval which lacks any evidence of a depositional trend and testify balance between the subsidence rate i e fault activity and the amount of sediment provided from the margin ii a coarsening upward middle interval pointing to a decrease in subsidence rate associated with an augment in sediment supply iii a fining upward upper interval locally preserved documenting a phase of tectonic quiescence associated with a progressive re equilibration of the tectonically induced morphological profile the basin scale unconformity which separates the montevarchi and torrente ciuffenna synthems was due to the entrance of the arno river into the basin as consequence of a piracy this event caused a dramatic increase in water discharge of the axial fluvial system and its consequent embanking such an erosional surface started to develop in the axial areas and propagated along the main tributaries triggering erosion of the alluvial fan deposits alluvial fan deposits of the torrente ciuffenna synthem accumulated above the unconformity during a phase of tectonic quiescence and show a fining upward depositional trend this trend was generated by a progressive decrease in sediment supply stemming out from upstream migration of the knickpoints developed during the embanking of the axial system

opening the carbon isotope vital effect black box 2 quantitative model for interpreting foraminiferal carbon isotope data interpretation of carbon isotope records from late quaternary planktonic foraminifers are confounded due to the presence of a significant physiological component in the carbon isotopic signal a quantitative carbon isotope qc model is presented which relates the carbon isotopic composition of a foraminiferal shell to the physiological processes of respiration and symbiont photosynthesis and to the 13c value of seawater co2 the qc model is calibrated with physiological and stable isotopic data from laboratory experiments with living planktonic foraminifers model simulations of chamber and shell 13c values with the symbiont bearing foraminifers orbulina universa and globigerinoides sacculifer suggest 1 variations in symbiont density and photosynthetic rate light level or habitat depth are the primary physiological parameters controlling intraspecific carbon isotopic variability in these species 2 respiration has little effect on the 13c of o universa and 3 each chamber in a multichambered foraminiferal test will have a distinct 13c value depending on its position in the test whorl size 13c value relationships reported for g sacculifer from fossil assemblages can be explained as a function of increasing symbiont density during ontogenetic development

profiling planktonic foraminiferal crust formation planktonic foraminifera migrate vertically through the water column during their life thereby growing and calcifying over a range of depth associated conditions some species form a calcite veneer crust or cortex at the end of their lifecycle this additional calcite layer may vary in structure composition and thickness potentially accounting for most of their total shell mass and thereby dominating the element and isotope signature of the whole shell here we apply laser ablation icp ms depth profiling to assess variability in thickness and mg ca composition of shell walls of three encrusting species derived from sediment traps compositionally mg ca is significantly lower in the crusts of neogloboquadrina dutertrei and globorotalia scitula as well as in the cortex of pulleniatina obliquiloculata independent of the species specific mg ca of their lamellar calcite shell wall thickness accounts for nearly half of the total thickness in both crustal species and nearly a third in cortical p obliquiloculata regardless of their initial shell wall thickness crust thickness and crustal mg ca decreases toward the younger chambers in n dutertrei and to a lesser extent also in g scitula in contrast the cortex of p obliquiloculata shows a nearly constant thickness and uniform mg ca through the complete chamber wall patterns in thickness and mg ca of the crust indicate that temperature is not the dominant factor controlling crust formation instead we present a depth resolved model explaining compositional differences within individuals and between successive chambers as well as compositional heterogeneity of the crust and lamellar calcite in all three species studied here

climate impact of late quaternary equatorial pacific sea surface temperature variations magnesium calcium data from planktonic foraminifera in equatorial pacific sediment cores demonstrate that tropical pacific sea surface temperatures ssts were 2 8 0 7 c colder than the present at the last glacial maximum glacial interglacial temperature differences as great as 5 c are observed over the last 450 thousand years changes in sst coincide with changes in antarctic air temperature and precede changes in continental ice volume by about 3 thousand years suggesting that tropical cooling played a major role in driving ice age climate comparison of sst estimates from eastern and western sites indicates that the equatorial pacific zonal sst gradient was similar or somewhat larger during glacial episodes extraction of a salinity proxy from the magnesium calcium and oxygen isotope data indicates that transport of water vapor into the western pacific was enhanced during glacial episodes

crustal section based on crop seismic data across the north tyrrhenian northern apennines adriatic sea abstract using deep seismic reflection data from the italian lithospheric exploration project crop in the central mediterranean region a 400 km long section composed of three different profiles crossing the northern tyrrhenian sea crop m 12a profile the northern apennines crop 03 and the adriatic sea crop m 16 is reconstructed and discussed new data allow us to outline a seismically consistent tectono stratigraphic setting for the crust and upper mantle of the northern apennines thrust belt system and its adriatic foreland time space analysis of the deformation of the investigated chain and identification of existing macrostratigraphic crustal intervals and tectonic units allow a reasonably controlled interpretation of the geodynamic evolution and of the main orogenic stages careful seismic reprocessing and application of advanced techniques to key zones of the explored area such as the tuscan archipelago were determinants in obtaining fundamental information for understanding of the complex lithospheric structures and their evolution profile interpretation supports that the northern apennine chain is dominated by a compressive thrust system crustal extension assumed by some authors as the dominating tectonic process for the whole tuscan apennine area represents a subordinate geodynamic event of the last stage tyrrhenian in the early cretaceous late jurassic the paleogeographic framework consisted of the europe and adria plates separated by the alpine tethys ocean during the late cretaceous early eocene adria europe convergence eo alpine stage and subduction beneath the adria plate closed the alpine tethys sea with the tethyan slab being clearly seismically imaged the first apenninic geodynamic stage occurred in the late oligocene early miocene with the opening of the balearic basin which generated a first lithospheric root of the apenninic chain in the tuscan archipelago area this root is represented by adria verging thrust faults that progressively flatten eastward upper parts of the west verging eo alpine thrust blocks were truncated by the east verging thrust faults of the balearic stage a deeper seismic reflector attributed to the top of the asthenosphere forms a mantle high below the elba island from the late miocene to present the corsica basin and western hinterland area were affected by extensional tectonics related to the tyrrhenian opening whereas compressional tectonics continued in the eastern hinterland and mostly on the eastward migrating foreland with development of a second lithospheric root constituted by high angle thrust faults these faults give rise to a huge basement culmination below the main apennines watershed impressive e directed gravity sliding of sedimentary blocks over their sloping basement occur generating the umbria marche shallow seismicity crustal shortening of the apennines system amounts to 170 km 14 km of which are due to the eo alpine stage 71 km to the balearic and 85 km to the tyrrhenian one in the frame of africa europe convergence the tyrrhenian apennines tectonodynamics were mainly conditioned by the mesozoic paleogeography

influences of temperature and secondary environmental parameters on planktonic foraminiferal mg ca a new core top calibration the accuracy of the mg ca paleothermometer is contested over the influences of secondary environmental parameters such as salinity and ph recent calibrations based on compiled sediment trap and laboratory culture data suggest moderate influences from salinity and ph core tops are the best analogues to downcore samples used for paleoceanographic reconstruction with well constrained environmental parameters and thus can be used to validate sediment trap and laboratory culture calibrations here we calibrate new core top mg ca data in globigerinoides ruber white and trilobatus sacculifer without final sac like chamber with sea surface temperature salinity and ph part of these coretops were previously used to argue for a large salinity effect on g ruber w mg ca arbuszewski et al 2010 http 10 0 3 248 j epsl 2010 10 035 our new g ruber w mg ca data are on average 12 lower than the previous results our calibrations yield mg ca temperature sensitivities of 8 1 0 7 c for g ruber w and 6 6 0 8 c for t sacculifer w o sac and mg ca salinity effects of 4 7 2 4 for g ruber w and 5 5 2 3 for t sacculifer w o sac these results agree well with culture experiments but discount the large salinity effects reported in previous core top studies our data reveal insignificant ph effects on mg ca in both species overall our core top calibrations for g ruber w and t sacculifer w o sac lend strong support to previous calibrations strengthening our confidence in the use of planktonic mg ca as a reliable proxy for sea surface temperature reconstructions less

growth stratal records of instantaneous and progressive limb rotation in the precordillera thrust belt and bermejo basin argentina analysis of synorogenic deposits preserved near the thrust front zone of the precordillera fold and thrust belt and in the bermejo foreland basin in central argentina documents the evolution of deformation during the last 5 myr as well as the thrust system kinematics seismic lines across the area display examples of progressive and instantaneous limb rotations the easternmost thrust plate of the central precordillera the niquivil thrust experienced episodic motion in two main stages a first thrust movement as a fault propagation fold and a second movement as a high angle anticlinal breakthrough fault after a period of quiescence growth strata deposited in the la pareja intermontane basin and the las salinas and bermejo anticline recorded continuous growth of eastern precordilleran structures beginning at 2 7 ma with uplift rates of 0 3 mm yr for the niquivil anticline 1 08 mm yr for the las salinas anticline and between 0 6 and 0 38 mm yr during the last 2 myr for the bermejo anticline once the eastern precordillera began to grow the propagation of the niquivil thrust stopped restricting the deformation to the young vallecito out of sequence thrust the complex geometry of growth strata deposited on the back limb of the las salinas anticline can be explained by using a model of a two step fault propagation fold with constant layer thickness the bermejo anticline of the eastern precordillera is formed by the simultaneous propagation of a shallow fault responsible for the fold shape and a deep fault that produced vertical uplift a growth triangle that documents instantaneous forelimb rotation for a fault propagation fold is recorded for the first time in a published seismic line

vital effects and beyond a modelling perspective on developing palaeoceanographical proxy relationships in foraminifera this paper primarily reviews our recent work on the biology and geochemistry of foraminifera with respect to their use as paleoceanographic proxies our approach to proxy validation and development is described primarily from a modeler s point of view the approach is based on complementary steps in understanding the inorganic chemistry inorganic isotope fractionation and biological controls that determine paleo tracer signals in organisms used in climate reconstructions integration of laboratory experiments field and culture studies theoretical considerations and numerical modeling holds the key to the method s success we describe effects of life processes in foraminifera on stable carbon oxygen and boron isotopes as well as mg incorporation into foraminiferal calcite shells stable boron isotopes will be used to illustrate our approach we show that a mechanism based understanding is often required before primary climate signals can be extracted from the geologic record because the signals can be heavily overprinted by secondary non climate related phenomena moreover for some of the proxies fundamental knowledge on the thermodynamic inorganic basis is still lacking one example is stable boron isotopes a paleo ph proxy for which the boron isotope fractionation between the dissolved boron compounds in seawater was not precisely known until recently attempts to overcome such hurdles are described and implications of our work for paleoceanographic reconstructions are discussed

the contribution of geostatistics to the characterisation of some bimrock properties abstract this paper introduces a geostatistical approach for characterising the morphological and spatial variability of rock inclusions in bimrocks and for attempting their direct mechanical characterization through an indirect description deduced by image analysis of outcrop images the study was carried out on the shale limestone chaotic complex slcc bimrock which is affected by several slope stability problems in the disused santa barbara open pit mine tuscany italy due to its complex heterogeneity the mechanical characterization of slcc was based on a limited number of non conventional shear tests bimtests due to the relevant influence of rock inclusions on bimrock strength the study focused on identifying the possible image parameters characterising content and variability of rock inclusions in each sampled picture a two step analysis was carried out for a identification of an image parameter centimetric scale that is able to grasp some property of rock fragment shape and size spatial distribution b verification of the correlation at the outcrop scale multimetric scale between the bimrock strength parameters and the new regionalised variables rev describing image properties related to rock fragment distribution a geostatistical approach was adopted for both steps but applied to two different problems at two different scales with different variables an extensive sampling of outcrop pictures was carried out and a variogram analysis was performed on the rock fragment indicator variable i b x y defined at the image scale and obtained through the digital segmentation of the collected pictures a very good link was observed between the geostatistical model parameters and the content size and spatial variability of rock fragments shown in every picture the values of the total sill of the block indicator variograms were then assumed as a new rev c tot x y defined all over the sllc outcrop a cross covariance was computed between the variogram total sill and the friction angle x y and cohesion c x y at the scale of the whole outcrop area and a preliminary analysis showed a likely correlation

stable carbon cycle climate relationship during the late pleistocene a record of atmospheric carbon dioxide co2 concentrations measured on the epica european project for ice coring in antarctica dome concordia ice core extends the vostok co2 record back to 650 000 years before the present yr b p before 430 000 yr b p partial pressure of atmospheric co2 lies within the range of 260 and 180 parts per million by volume this range is almost 30 smaller than that of the last four glacial cycles however the apparent sensitivity between deuterium and co2 remains stable throughout the six glacial cycles suggesting that the relationship between co2 and antarctic climate remained rather constant over this interval

history of carbonate ion concentration over the last 100 million years abstract instead of having been more or less constant as once assumed it is now apparent that the major ion chemistry of the oceans has varied substantially over time for instance independent lines of evidence suggest that calcium concentration ca2 has approximately halved and magnesium concentration mg2 approximately doubled over the last 100 million years on the other hand the calcite compensation depth and hence the caco3 saturation has varied little over the last 100 my as documented in deep sea sediments we combine these pieces of evidence to develop a proxy for seawater carbonate ion concentration co32 over this period of time from the calcite saturation state which is proportional to the product of ca2 times co32 but also affected by mg2 we can calculate seawater co32 our results show that co32 has nearly quadrupled since the cretaceous furthermore by combining our co32 proxy with other carbonate system proxies we provide calculations of the entire seawater carbonate system and atmospheric co2 based on this reconstructed atmospheric co2 is relatively low in the miocene but high in the eocene finally we make a strong case that seawater ph has increased over the last 100 my

crustal shortening and duplication of the moho in the northern apennines a view from seismic refraction data abstract a reappraisal of the dss refraction seismic campaigns of 1978 and 1974 in the northern apennines and the northern tyrrhenian sea after digitization of the original analog data and a new interpretation of crustal structures are presented in this paper the layering of the adria crust consists of a low velocity lower crust topped by a 6 7 km s horizon and an upper crust again formed by a low velocity layer capped by a faster one in the tuscany sector the crust mantle boundary and lower crust show attenuated velocities and a reduced thickness with respect to the adriatic counterpart these differences are due to the extensional tectonics restricted to tuscany and occurred in a high heat flow regime related to an uplifting astenosphere it has been confirmed that a deep thrust is responsible for moho doubling in correspondence with the zero bouguer anomaly line the tuscan moho overlaps the umbro marchean one for a length of about 30 km it is hypothesized that another shallower thrust involves upper crust in the mid tuscany range mt cetona and perugia massifs had their roots in the mantle and that subsequent extensional tectonics obliterated every trace of thrusting in lower crust and mantle rocks no conclusive proof of the existence of a european moho below a tuscan one in the area underneath elba has yet been found revision of dss data excludes the presence of a refractor reflector 60 km deep the same data however are compatible with the existence of a crust mantle boundary at 30 35 km depth

a sagging along the eastern chianti mts italy abstract a deep seated gravitational slope deformation dgsd affects the eastern side of the chianti mts ridge it develops in an n s to nw se direction and is 10 km wide and 3 4 km long this area corresponds to the eastern side of a main antiform characterised by east verging folds and thrusts involving bedrock of the mesozoic paleogene tuscan units particularly sandstones containing interlayered highly fractured and deformed ligurian rocks shales and limestones with olistostromes the foot of the slope is characterised by tilted plio pleistocene deposits unconformably sealing the bedrock structures as folds thrusts and faults the most significant morphological features are a main escarpment trenches several secondary and counter slope escarpments that together indicate large scale gravitational phenomena the main escarpment is responsible for the headward retreat of the slope and is deeply segmented by numerous arcuate niches that reveal differential movements of single blocks the dgsd is also dissected by sw ne trending streams that often deepen inside the n s trenches minor landslides due to local instability are also present at the foot of the slope the older continental pliocene deposits of the upper valdarno basin crop out although tilted by tectonic movements the deposits have not been severely affected by gravitational deformations this indicates that the movement is a typical sagging a large landslide at an embryonic stage affecting the upper part of the slope but not reaching the valley bottom the deformations are absorbed in the rock mass which is also partially drained by stream incision that prevents high pore pressure the occurrence of down slope and down movement facing escarpments and up slope and up movement facing counter slope escarpments indicate a sagging characterised by a listric spoon shaped geometry the dgsd has a style similar to crustal extensional tectonics such as morton and black s crustal attenuation model although few chronological indications of movements are present the fact that late pleistocene debris deposits widespread in the northern and central apennines are not found at the contact between the escarpment and the trenches suggests a post glacial activity for at least part of the movements recognizing embryonic stage collapse is of primary importance in assessing geological hazard and risk because rapid evolution and collapse could follow

secular oscillations in the carbonate mineralogy of reef building and sediment producing organisms driven by tectonically forced shifts in seawater chemistry the primary mineralogy of oolites and early marine carbonate cements led sandberg nature 305 1983 19 22 to divide the phanerozoic eon into three intervals of aragonite seas and two intervals of calcite seas hardie geology 24 1996 279 283 has shown that these oscillations together with synchronous oscillations in the mineralogy of marine potash evaporites can be explained by secular shifts in the mg ca ratio of seawater driven by changes in spreading rates along mid ocean ridges the hardie model also predicts that high mg calcite should precipitate along with aragonite as it does in today s aragonite sea we have uncovered oscillations in the carbonate mineralogy of hypercalcifying organisms ones that have produced massive skeletons large reefs or voluminous bodies of sediment that correspond to sandberg s aragonite seas and calcite seas and that are predicted by the hardie model particular groups of corals sponges and algae appear to have been dominant reef builders only when favored by an appropriate mg ca ratio in seawater in early and middle paleozoic calcite seas calcite i reefs were dominated by calcitic tabulate heliolitid and rugose corals and calcitic stromatoporoids in contrast during the period of late paleozoic early mesozoic aragonite seas aragonite ii aragonitic groups of sponges scleractinian corals and phylloid algae as well as high mg calcitic red algae were principal reef builders during late cretaceous time at the acme of calcite ii massive rudists displaced aragonitic hermatypic corals in today s aragonite sea aragonite iii scleractinian corals are again dominant reef builders along with high mg calcitic coralline algae major sediment producing algae exhibit temporal patterns similar to those of reef builders calcitic receptaculitids flourished during calcite i whereas aragonitic dasycladaceans did not become dominant rock formers until aragonite ii during calcite ii calcitic nannoplankton formed massive coccolith chalks in warm shallow seas of the late cretaceous after the mg ca ratio of seawater had reached a very low value and calcium concentration a very high value as the mg ca ratio of seawater rose and calcium concentration fell during the cenozoic era individual coccoliths on average became less massive and encrusted cells less thickly by pliocene time during aragonite iii the prominent genus discoaster secreted only narrow rayed coccoliths that covered less than 25 of the cell surface also during aragonite iii the aragonitic green alga halimeda emerged as the dominant skeletal sediment producer in reef tracts the influence of seawater chemistry on skeletal secretion appears to have been especially strong for morphologically simple taxa that exert relatively weak control over their own calcification such groups include algae sponges corals and bryozoans morphological simplicity also permits these groups to adopt vegetative or colonial modes of growth that confer success in competition for space on reefs this linkage in addition to the basic chemical demands of hypercalcification has given the mg ca ratio of seawater strong control over the success of individual reef building taxa more generally this ratio appears to have strongly influenced evolutionary changes in the skeletal mineralogy of sponges and cheilostome bryozoans throughout their history we conclude that throughout phanerozoic time a chain of causation has extended from mid ocean ridge processes via seawater chemistry to the mineralogical and biological composition of reef communities and bioclastic carbonate deposits

tectonic regime granite emplacement and crustal structure in the inner zone of the northern apennines tuscany italy a new hypothesis abstract geological and geophysical data on the inner part of the northern apennines and the deep 4 km geothermal wells contained therein have been reviewed in order to better characterize the tectonic regime of the region the area is affected by neogene quaternary igneous activity reduced crustal thickness high heat flow and active geothermal systems the available information leads to the following conclusions 1 at present part of the chain including its inner regions are undergoing extensional activity a tectonic situation in southern tuscany dating back to the late tortonian however the simple model of solely extensional tectonics cannot exhaustively account for the phenomena observed in the area as there is ample evidence of compressive events of pliocene and pleistocene ages 2 the geophysical data indicate reduced lithosphere thickness and the uprising of the asthenosphere to shallow crust levels the upper crust has been intruded by many granite bodies and the brittle ductile transition is probably very shallow an integrated geophysical model which accounts for heat flow seismic gravimetric and magnetic data indicates that a regional strong reflector rather than coinciding with the beginning of the ductile crust more likely indicates the presence of deep brines rather than a gneiss core complex and a generalized post collision extensional model cameli et al 1993 we support a more complex geodynamic framework including compressive phases of the internal zone and re activation of the thrust of the apennines as a consequence of crustal thrust emplacements from the late tortonian in the frame of a subducting delaminated lithosphere

gas geochemistry applied to earthquake prediction an overview terrestrial gases in groundwater and soil air have been extensively studied in recent years in seismically active areas especially in ussr china japan and united states in search of premonitory changes that might be useful for earthquake prediction concentrations of radon helium hydrogen mercury carbon dioxide and several other volatiles have been found generally to be anomalously high along active faults suggesting that the faults may be paths of least resistance for the terrestrial gases generated or stored in the earth to escape to the atmosphere temporal gas concentration changes with durations of a few hours to many months have been observed before many large earthquakes at a relatively small number of favorably situated stations at epicentral distances of up to several hundreds of kilometers these sensitive stations are generally located along active faults especially at intersections or bends of faults or some other structurally weak zones possibly because of tectonic strain concentration at such places however gas concentrations especially those measured at or near the ground surface may also be significantly affected by meteorological hydrological and other nontectonic changes in the environment the nontectonically induced variations must be carefully eliminated or recognized in the search of true earthquake related anomalies

impact of blasting on groundwater composition in a fracture in canada s underground research laboratory groundwater composition in a discrete water bearing fracture in granitic rock at the underground research laboratory manitoba was monitored during a period of underground excavation of adjacent rock to determine the impact of conventional blasting techniques and rock fracturing on the concentration of dissolved constituents this work has relevance to the study of hydrogeochemical anomalies associated with seismic activity short lived anomalies such as decreases in dissolved anion cl f br so4 and gas he rn concentrations and concurrent increases in no3 and o2 concentrations were seen shortly after two blasts located opposite the groundwater sampling site a third blast downstream of the site resulted in variability in dissolved gases concentrations but showed no impact on dissolved anion concentrations the results are compared with various models used to account for hydrogeochemical fluctuations associated with earthquakes the data best fit a general form of the aquifer breaching fluid mixing model in which hydrochemical responses are caused by localized changes in hydraulic conductivity along the plane of a fracture which in turn cause changes in mixing ratio of groundwater at the monitoring site

variation in fracture patterns in damage zones related to strike slip faults interfering with pre existing fractures in sandstone calcione area southern tuscany italy abstract this paper deals with the effects of pre existing fractures on the development of damage zones related to meter and decameter strike slip faults which affected late oligocene early miocene sandstone in the calcione area southern tuscany italy strike slip faults dissected rock masses locally affected by pervasive pre existing fractures related to previous deformational events two different domains were identified rock masses affected and unaffected or relatively unaffected by pre existing fractures strike slip faults affecting the two domains made it possible to compare the different configurations of fracture patterns related to isolated or interacting fault segments new data is provided on scaling relations between i fault length and the length of related fractures ii mean step length and width for overstepping fault segments iii angular values at the intersection of the fault plane and related fractures scaling relations obeyed a positive power law for faults dissecting sandstone unaffected by pre existing fractures on the contrary no scaling relations were recognized for faults dissecting sandstone affected by pre existing fractures the development of strike slip faults on rock masses affected by pre existing fractures can simulate splays apparently related to faulting three main points were categorized for detecting deceptive cases there is a real chance of a deceptive fracture pattern if i the angular values at the intersection of the fault and its fractures mode i opening fracture exceed 50 in the wall damage zone ii the scaling relation between fault length and maximum fracture length does not fit a power law iii fractures acted as shear fractures the resulting framework provides additional data for understanding the development and architecture of strike slip faults

out of sequence thrusts out of sequence thrusts oost are those thrusts which do not obey the foreland propagating or in sequence deformation style they include both isolated thrusts which develop hindward of the thrust front and sequences of break back thrusts which propagate from the foreland to the hinterland two end members of a series of oost types are recognized 1 older in sequence thrusts which are reactivated along their entire length and 2 completely new thrusts which propagate through already deformed thrust sheets between the two end members are thrusts composed partially of reactivated in sequence thrust sequences and partially of new entirely out of sequence segments oosts can be initiated for a variety of reasons including 1 keeping the orogenic wedge at critical taper 2 break back sequences from the suture zone in the overriding plate 3 ramping to overcome a sticking point which inhibits in sequence thrust propagation and 4 during simultaneous displacement along two stacked thrusts culminations which bow up segment of the upper thrust may be chopped through to permit continued displacement on the upper thrust many different types of thrust behavior including gravity sliding plucking and derivation of isolated horses from ramps may mimic some of the characteristics of oosts consequently it may be difficult to conclusively prove an oost origin for a complex thrust geometry

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

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

a biomineralization model for the incorporation of trace elements into foraminiferal calcium carbonate measurements of srca of benthic foraminifera show a linear decrease with water depth which is superimposed upon significant variability identified by analyses of individual foraminifera new data for cdca support previous work in defining a contrast between waters shallower and deeper than 2500 m measured element partition coefficients in foraminiferal calcium carbonate relative to sea water d have been described by means of a one box model in which elements are extracted by rayleigh distillation from a biomineralization reservoir that serves for calcification with a constant fractionation factor such that d 1 f 1 f where f is the proportion of ca remaining after precipitation a modification to the model recognises differences in element speciation the model is consistent with differences between dsr dba and dcd in benthic but not planktonic foraminifera depth variations in d for sr and ba are consistent with the model as are differences in depth variation of dcd in calcitic and aragonitic benthic foraminifera the shallower depth variations may reflect increasing calcification rates with increasing water depth to an optimum of about 2500 m observations of unusually lower dcd for some deep waters not accompanied by similar dsr or dba may be because of dissolution or a calcification response to a lower carbonate saturation state

an explanation of the effect of seawater carbonate concentration on foraminiferal oxygen isotopes abstract stable oxygen isotope ratios of foraminiferal calcite are widely used in paleoceanography to provide a chronology of temperature changes during ocean history it was recently demonstrated that the stable oxygen isotope ratios in planktonic foraminifera are affected by changes of the seawater chemistry carbonate system the 18 o of the foraminiferal calcite decreases with increasing co 3 2 concentration or p h this paper provides a simple explanation for seawater chemistry dependent stable oxygen isotope variations in the planktonic foraminifera orbulina universa which is derived from oxygen isotope partitioning during inorganic precipitation the oxygen isotope fractionation between water and the dissolved carbonate species s h 2 co 3 hco 3 co 3 2 decreases with increasing p h provided that calcium carbonate is formed from a mixture of the carbonate species in proportion to their relative contribution to s the oxygen isotopic composition of caco 3 also decreases with increasing p h the slope of shell 18 o vs co 3 2 of orbulina universa observed in culture experiments is 0 0022 mol kg 1 1 spero et al 1997 whereas the slope derived from inorganic precipitation is 0 0024 mol kg 1 the theory also provides an explanation of the nonequilibrium fractionation effects in synthetic carbonates described by kim and o neil 1997 which can be understood in terms of equilibrium fractionation at different p h the results presented here emphasize that the oxygen isotope fractionation between calcium carbonate and water does not only depend on the temperature but also on the p h of the solution from which it is formed

surface ocean ph response to variations in pco2 through two full glacial cycles abstract knowledge of past atmospheric pco 2 is important for evaluating the role of greenhouse gases in climate forcing ice core records show the tight correlation between climate change and pco 2 but records are limited to the past 900 kyr we present surface ocean ph and pco 2 data reconstructed from boron isotopes in planktonic foraminifera over two full glacial cycles 0 140 and 300 420 kyr the data co vary strongly with the vostok pco 2 record and demonstrate that the coupling between surface ocean chemistry and the atmosphere is recorded in marine archives allowing for quantitative estimation of atmospheric pco 2 beyond the reach of ice cores

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

ground truthing the boron isotope paleo ph proxy in planktonic foraminifera shells partial dissolution and shell size effects 1 sediment samples from the ontong java plateau in the pacific and the 90 east ridge in the indian ocean were used to investigate whether shell size and early diagenesis affect 11b of the symbiont bearing planktonic foraminifer globigerinoides sacculifer in pristine shells from both study locations we found a systematic increase of 11b and mg ca with shell size shells in the sieve size class 515 865 m revealed 11b values 2 1 to 2 3 higher than shells in the 250 380 m class this pattern is most likely due to differences in symbiont photosynthetic activity and its integrated effect on the ph of the foraminiferal microenvironment we therefore suggest smaller individuals must live at approximately 50 100 m water depth where ambient light levels are lower using the empirical calibration curve for 11b in g sacculifer only shells larger than 425 m reflect surface seawater ph partial dissolution of shells derived from deeper sediment cores was determined by shell weight analyses and investigation of the shell surface microstructure by scanning electron microscopy the 11b in partially dissolved shells is up to 2 lower relative to pristine shells of the same size class in agreement with a relatively higher weight loss in smaller shells samples from the ontong java plateau show a more pronounced dissolution effect than larger shells on the basis of the primary size effect and potential postdepositional dissolution effects we recommend the use of shells that are visually pristine and in the case of g sacculifer larger than 500 m for paleoreconstructions