sources and dispersal of land based runoff from small hawaiian drainages to a coral reef insights from geochemical signatures abstract land based sediment and contaminant runoff is a major threat to coral reefs and runoff reduction efforts would benefit from knowledge of specific runoff sources geochemical signatures of small drainage basins were determined in the fine fraction of soil and sediment then used in the nearshore region of a coral reef fringed urban embayment on southeast oahu hawaii to describe sources and dispersal of land based runoff the sedimentary rare earth element ratio la yb n showed a clear distinction between the two main rock types in the overall contributing area tholeiitic and alkalic olivine basalt based on this geochemical signature it was apparent that the majority of terrigenous sediment on the reef flat originated from geologically old tholeiitic drainages sediment from one of five tholeiitic drainages had a distinct geochemical signature and sediment with this signature was dispersed on the reef flat 2 km west and 150 m offshore of the contributing basin sediment and the anthropogenic metals cd pb and zn were entrained in runoff from the most heavily urbanized region of the watershed although anthropogenic cd and zn had localized distributions close to shore anthropogenic pb was found associated with fine sediment on the westernmost part of the reef flat and 400 m offshore illustrating how trade wind driven sediment transport can increase the scale of runoff impacts to nearshore communities our findings show that sediment geochemical signatures can provide insights about the source and dispersal of land based runoff in shallow coastal environments the application of such knowledge to watershed management and habitat remediation efforts can aid in the protection and restoration of runoff impacted coastal ecosystems worldwide

supply and dispersal of flood sediment from a steep tropical watershed hanalei bay kaua i hawai i usa in contrast to many small mountainous watersheds in temperate coastal regions where fl uvial discharge and wave energy commonly coincide deposition and reworking of tropical fl ood sediment can be seasonally decoupled and this has important implications for coral reef ecosystems an understanding of the interaction between tropical fl ood sedimentation and wave climate is essential to identifying and mitigating effects of watershed changes on coral reefs as urbanization and climate change proceed sedimentary facies and isotopic properties of sediment in hanalei bay on the island of kaua i hawai i usa were used to assess deposition and reworking of fldeposits from the hanalei river in a case study demonstrating the potential ecosystem effects of runoff from a steep tropical watershed in hanalei bay the youngest and thickest terrigenous sediment was consistently present near the river mouth and in a bathymetric depression that acted as at least a temporary sediment sink during this 2 yr study the largest fl ood events occurred in late winter and spring 2006 substantial terrestrial sediment delivered by those fl oods still remained in the bay as of june 2006 because oceanic conditions were not suffi ciently energetic to transport all of the sediment offshore additional sediment was deposited in the bay by a summer 2006 fl ood that coincided with seasonal low wave energy in most years fl ood sediment accumulating in the bay and on its fringing reefs would be remobilized and advected out of the bay during winter when the wave climate is energetic turbidity and sedimentation on corals resulting from late spring and summer fl oods during low wave energy could have a greater impact on coral reef ecosystems than fl oods in other seasons an effect that could be exacerbated if the incidence and sediment load of tropical summer fl oods increase due to urbanization and climate change

emission of bromine and iodine from mount etna volcano 1 constraining fluxes of volcanic bromine and iodine to the atmosphere is important given the significant role these species play in ozone depletion however very few such measurements have been made hitherto such that global volcanic fluxes are poorly constrained here we extend the data set of volcanic br and i degassing by reporting the first measurements of bromine and iodine emissions from mount etna these data were obtained using filter packs and contemporaneous ultraviolet spectroscopic so2 flux measurements resulting in time averaged emission rates of 0 7 kt yr 1 and 0 01 kt yr 1 for br and i respectively from april to october 2004 from which we estimate global br and i fluxes of order 13 range 3 40 and 0 11 range 0 04 6 6 kt yr 1 observed changes in plume composition highlight the coherent geochemical behavior of hcl hf hbr and hi during magmatic degassing and strong fractionation of these species with respect to so2

improved provenance tracing of asian dust sources using rare earth elements and selected trace elements for palaeomonsoon studies on the eastern tibetan plateau abstract the asian monsoon forms an important part of the earth s climate system yet our understanding of the past interactions between its different sub systems the east asian and indian monsoons and between monsoonal winds and other prevailing wind currents such as the westerly jet is limited particularly in central asia this in turn affects our ability to develop climate models capable of accurately predicting future changes in atmospheric circulation patterns and monsoon intensities in asia provenance studies of mineral dust deposited in terrestrial settings such as peat bogs can address this problem directly by offering the possibility to examine past deposition rates and wind direction and hence reconstruct past atmospheric circulation patterns however such studies are challenged by several issues most importantly the identification of proxies that unambiguously distinguish between the different potential dust sources and that are independent of particle size in addition a single analytical method that is suitable for sample preparation of both dust source i e desert sand soil and receptor i e dust archive such as peat or soil profiles material is desirable in order to minimize error propagation derived from the experimental and analytical work here an improved geochemical framework of provenance tracers to study atmospheric circulation patterns and palaeomonsoon variability in central asia is provided by combining for the first time mineralogical as well as major and trace elemental sc y th and the rare earth elements information on chinese central chinese loess plateau northern qaidam basin and taklamakan badain juran and tengger deserts indian thar desert and tibetan eastern qinghai tibetan plateau dust sources quartz feldspars and clay minerals are the major constituents of all studied sources with highly variable calcite contents reflected in the cao concentrations chinese and tibetan dust sources are enriched in middle ree relative to the upper continental crust and average shale but the thar desert has a ree signature distinctly different from all other dust sources there are significant differences in major trace and ree compositions between the coarse and fine fractions of the surface sands with the finest 2 o 3 fe 2 o 3 mno mgo and k 2 o and the all ree normalized to post archean australian shale paas are particle size independent tracers of which combinations of y ree la yb y tb y la and eu eu can be used to distinguish the thar desert the chinese deserts the chinese loess plateau and the tibetan soils their independence upon grain size means that these tracers can be applied to the long range provenance tracing of asian dust even when only bulk samples are available in the source region combinations of la th y tb y ree sc la and y er distinguish the tibetan soils from the chinese loess plateau and the chinese deserts la th and notably th ree isolate the signature of the badain juran desert and the combination of sc la and y er that of the taklamakan desert the similarity in all trace and ree based provenance tracers between the northern qaidam basin and tengger desert suggests that these two deposits may have a common aeolian source

from present rivers to old terrigenous sediments the evolution of the drainage system in the eastern southern alps terra nova 22 218 226 2010 abstract the eastern southern alps are presently dominated by southward drainage systems feeding the venetian friulian plain confined to the south of the insubric lineament following the assumption that river sediments reflect in the first instance the rocks outcropping in their catchments the comparison between present fluvial and old terrigenous sediments lets us to evaluate changes in provenance since the late miocene when the basement exhumation along the valsugana thrust system took place as indicated by apatite fission track data this tectonic event determined the onset of the main drainage systems the evolution of which has been depicted tracking the petrographic signatures from the present back to the late miocene provenance data show important episodes of stream piracy and watershed migration in response to tectonic uplift in the southern alps as well as to the messinian salinity crisis and the quaternary glaciations terra nova 00 1 9 2010

tropical cyclone driven erosion of the terrestrial biosphere from mountains the transfer of organic carbon from the terrestrial biosphere to the oceans via erosion and riverine transport constitutes an important component of the global carbon cycle measurements of particulate organic carbon load and composition in the liwu river taiwan during cyclone triggered floods suggest that tropical cyclones may facilitate the delivery of non fossil particulate organic carbon to the ocean and its subsequent burial the transfer of organic carbon from the terrestrial biosphere to the oceans via erosion and riverine transport constitutes an important component of the global carbon cycle1 2 3 4 more than one third of this organic carbon flux comes from sediment laden rivers that drain the mountains in the western pacific region3 5 this region is prone to tropical cyclones but their role in sourcing and transferring vegetation and soil is not well constrained here we measure particulate organic carbon load and composition in the liwu river taiwan during cyclone triggered floods we correct for fossil particulate organic carbon using radiocarbon and find that the concentration of particulate organic carbon from vegetation and soils is positively correlated with water discharge floods have been shown to carry large amounts of clastic sediment6 non fossil particulate organic carbon transported at the same time may be buried offshore under high rates of sediment accumulation7 8 9 we estimate that on decadal timescales 77 92 of non fossil particulate organic carbon eroded from the liwu catchment is transported during large cyclone induced floods we suggest that tropical cyclones which affect many forested mountains within the intertropical convergence zone10 may provide optimum conditions for the delivery and burial of non fossil particulate organic carbon in the ocean this carbon transfer is moderated by the frequency intensity and duration of tropical cyclones

neogene patterns of relative plate motion for africa europe some implications for recent central mediterranean tectonics a detailed relative motion picture for the neogene africa europe plate kinematics is presented the kinematic reconstruction was carried out using the finite difference solution between the rotation parameters determined for anomalies 7 to 2 in the africa north america europe plate motion circuit the analysis shows a motion of africa with respect to europe which is nne directed during late oligocene to burdigalian times becoming nnw trending from the langhian to the early tortonian from upper tortonian times onward the motion changes to a clear north west directed convergence major late neogene tectonic features of the central mediterranean region can to a large extent be explained within the context of the reconstructed major plate motions late tortonian to recent africa europe slip vectors are compatible with a variety of geological phenomenoa such as north west directed subduction beneath calabria south east translation of calabria and extension in the tyrrhenian sea north west trending slip vectors from thrust earthquakes between gibraltar and sicily and dextral strike slip across the north african margin

eoalpine and mesoalpine tectonics in the southern alps according to structural and stratigraphic data eoalpine and mesoalpine tectonics can be clearly recognized in the southern alps and distinguished from the better known neoalpine deformation

bed sediment associated trace metals in an urban stream oahu hawaii of the 117 stream and lake systems sampled nationwide fish from manoa stream on oahu hawaii have consistently shown the highest pb concentrations therefore a detailed study was conducted to examine total metal contents in bed sediments from a 5 8 km stretch of manoa stream a total of 123 samples 63 m were examined for 18 elements and 14 samples for 21 elements selected samples were also examined using different leach solutions to examine metal phase associations all trace metal data computations of enrichment ratios and the modified index of geoaccumulation point to mineralogical control for cr and ni minor anthropogenic contamination for ba cd cu hg and zn and a very strong contamination signal for pb maximum pb contents up to 1080 mg kg 1 were associated with anthropogenic material dumping in minor tributaries storm sewer sediments and sediments in the lower section of the basin proportionally pb had the highest non residual component of elements examined dominantly in the reducible phase associated with mn and amorphous fe oxyhydroxides the contamination signal was typically lowest in the undisturbed headwater reach of the basin above 5 1 km with significant increases throughout the residential and commercial institutional zones of the mid basin the spatial pattern of bed sediment contamination and evidence from storm sewer outlet sediments strongly indicates that pb and to a lesser degree some other metals is still being transported to the stream and the primary agent is soil erosion and transport of metals sorbed to sediments the primary source of sediment associated metals is considered to be the automobile though other minor sources can not be ruled out

chemical weathering mass loss and dust inputs across a climate by time matrix in the hawaiian islands we determined the total mass loss and rate of chemical weathering from three minimally eroded hawaiian lava flows that are 10 170 and 350 ka old using a backhoe we sampled the entire weathering zone at 28 sites and measured the depletion or enrichment of each major element in each soil horizon relative to parent material we were able to assess the influence of both climate and substrate age on chemical weathering because each flow crosses a precipitation gradient from 600 to 2500 mm yr 1 mass loss rates were highest for the 0 10 ka interval under the wettest climatic conditions 54 t km 2 yr 1 and decreased to near zero in the wet sites during the 10 170 and 170 350 ka intervals not surprisingly weathering rates were lower in drier sites 24 t km 2 yr 1 from 0 10 ka to b 2tk m 2 yr 1 thereafter however the effects of precipitation were non linear there was a precipitation threshold below which mass loss was relatively small and above which mass loss was substantial but insensitive to increased rainfall chemical weathering rates depend on tectonic uplift erosion climate rock type or some combination thereof by working on stable uneroded surfaces of a single rock type across a well constrained precipitation gradient we were able to identify another potential driver the rate of dust deposition although hawai i is one of the least dusty places in the northern hemisphere dust inputs reached 82 of the total mass loss from the weathering zone at some sites and averaged 30 on the 170 ka flow this highlights the potential importance of dust as a component of observed weathering fluxes from catchments worldwide

geomorphic tectonic control of sediment discharge to the ocean the importance of small mountainous rivers analysis of data from 280 rivers discharging to the ocean indicates that sediment loads yields are a log linear function of basin area and maximum elevation of the river basin other factors controlling sediment discharge e g climate runoff appear to have secondary importance a notable exception is the influence of human activity climate and geology on the rivers draining southern asia and oceania sediment fluxes from small mountainous rivers many of which discharge directly onto active margins e g western south and north america and most high standing oceanic islands have been greatly underestimated in previous global sediment budgets perhaps by as much as a factor of three in contrast sediment fluxes to the ocean from large rivers nearly all of which discharge onto passive margins or marginal seas have been overestimated as some of the sediment load is subaerially sequestered in subsiding deltas before the proliferation of dam construction in the latter half of this century rivers

temporal and spatial variability in the flow and dispersal of suspended sediment on a fringing reef flat molokai hawaii abstract a multi year study was conducted on a shallow fringing reef flat on molokai hawaii to determine the temporal and spatial dispersal patterns of terrigenous suspended sediment during this study trade wind conditions existed for the majority of the year on the reef flat the trade wind conditions produced strong currents and resuspended moderate amounts of sediment on the reef flat on a daily basis during the year of study resulting in an overwhelming contribution to the total sediment flux the magnitude and direction of the trade winds relative to the orientation of the coastline the shallow relief and broad morphology and tidal elevation provided the primary control of the physical processes that resuspended and transported sediment on the reef flat over the period of record spatial data indicate that much of the terrigenous sediment resuspended on the reef flat is transported predominantly alongshore and is confined to the inner to mid reef flat evidence for the limited across shore mixing and transport is provided by the dominantly alongshore wind driven currents during trade wind conditions and the well defined across shore gradient in percentage calcium carbonate of the suspended sediment regions of slightly offshore suspended sediment transport along the reef flat can be attributed to the circulation pattern set up by the interaction between the trade winds coastal morphology and anthropogenic coastal structures i e fish ponds and wharf the regions in which sediment were seen to move offshore provide the strongest link between the sediment dynamics on reef flat and fore reef and qualitatively appears to be correlated with low coral coverage on the fore reef

tectonics of the dolomites southern alps northern italy abstract in post variscan times the dolomites underwent a number of tectonic events which may be summarized as follows permian and triassic rifting phases broke the area into n s trending basins with different degrees of subsidence a middle triassic transpressive event then deformed the region along a n70 e axis generating flower structures within the basement volcano tectonic domal uplift and subsequent caldera formation occurred at the same time as the late ladinian magmatism early jurassic rifting also controlled the subsidence which increased eastward this long period of deformation was followed by a pre neogene late cretaceous palaeogene e w ene wsw compression which generated a w vergent belt possibly equivalent to the folded foreland of the dinaric chain a 70 km e w section of the dolomites indicates shortening of at least 10 km during the neogene the dolomites as far north as the insubric lineament were the innermost part of a s vergent thrust belt the basement of the dolomites was thrust southwards along the valsugana line onto the sedimentary cover of the venetian prealps for at least 10 km this caused a regional uplift of 3 5 km the valsugana line and its backthrusts on the northern side of the central dolomites generated a 60 km wide pop up in the form of a synclinorium within which the sedimentary cover adapted itself mainly by flexural slip often forming triangle zones the shortening linked to this folding is about 5 km with neogene thrusts faulting and folding pre existing thrust planes on the north eastern side of the dolomites neogene deformation is apparently more strictly controlled by the transpressive effects of the insubric lineament and shortening of the sedimentary cover may be greater than in the central dolomites minor deformation linked to the giudicarie belt is present in the western dolomites the present structure of the dolomites is thus the result of a number of tectonic events of different significance and different strike only a 3 dimensional restoration can unravel the true structure of the dolomites

spatial and temporal variability of trace element concentrations in an urban subtropical watershed honolulu hawaii trace metal concentrations in soils and in stream and estuarine sediments from a subtropical urban watershed in hawaii are presented the results are placed in the context of historical studies of environmental quality water soils and sediment in hawaii to elucidate sources of trace elements and the processes responsible for their distribution this work builds on earlier studies on sediments of ala wai canal of urban honolulu by examining spatial and temporal variations in the trace elements throughout the watershed natural processes and anthropogenic activity in urban honolulu contribute to spatial and temporal variations of trace element concentrations throughout the watershed enrichment of trace elements in watershed soils result in some cases from contributions attributed to the weathering of volcanic rocks as well as to a more variable anthropogenic input that reflects changes in land use in honolulu varying concentrations of as cd cu pb and zn in sediments reflect about 60 a of anthropogenic activity in honolulu land use has a strong impact on the spatial distribution and abundance of selected trace elements in soils and stream sediments as noted in continental us settings the phasing out of pb alkyl fuel additives has decreased pb inputs to recently deposited estuarine sediments yet a substantial historical anthropogenic pb inventory remains in soils of the watershed and erosion of surface soils continues to contribute to its enrichment in estuarine sediments concentrations of other elements e g cu zn cd however have not decreased with time suggesting continued active inputs concentrations of ba co cr ni v and u although elevated in some cases typically reflect greater proportions attributed to natural sources rather than anthropogenic input

brittle deformation in pitted pebble conglomerates abstract the fracture patterns produced in pitted pebble conglomerates from the alpine molasse and the carboniferous of northern spain have been studied in relation to the stress concentrations which were produced in the conglomerates during their deformation the stress distributions which develop around pebble contacts at different stages of their pitting history have been determined from photoelastic experiments the development of different types of fracture having dominantly tensile or shear components and their distribution within the pebbles are shown to be related to the mineralogy of the pebbles the strength of the matrix and the amount of deformation the conglomerate has suffered

organic carbon fluxes to the ocean from high standing islands the transfer of terrestrially derived yet poorly quantified organic carbon to the oceans is an important yet unagreed upon proportion of the world s carbon budget the few data that exist suggest that high standing oceanic islands in the southwest pacific may make important contributions to the overall terrestrial flux of particulate organic carbon poc to the oceans we have determined the poc flux from several streams in new zealand with those data and previous measurements from taiwan and papua new guinea we estimate the poc flux from high standing islands in the southwest pacific to be 48 1012 g c yr 1 a value slightly lower than previous estimates these islands which make up only 3 of earth s landmass contribute 17 35 of the estimated poc entering the world s oceans annually and thus may be important sources of terrestrial carbon to the ocean anthropogenic activities especially deforestation and forest harvesting have probably exacerbated the natural flux few to no data exist for many of these islands and thus a more detailed assessment awaits further measurements

refractory element mobility in volcanic soils refractory trace element concentrations in strongly weathered hawaiian soils ranging in age from 20 to 4100 ka are highly elevated over parent rock values due to extensive mass loss of more soluble major elements during pedogenesis nb and ta exhibit virtually no mobility soil nb ta ratios are within the range of fresh bedrock even when soil nb concentrations are residually enriched by a factor of 10 in contrast al zr and hf are depleted relative to nb in surface soil horizons but are enriched at depth clearly indicating mobility of these elements variations in th nb ratios in soil profiles indicate significant th mobility within the soil column however mass balance calculations require that accretion of th enriched asian dust has resulted in a net increase in th in some soils soils developed on a 150 ka rainfall gradient show that the mobility and loss of zr increase with mean annual precipitation

provenance of dust in the pacific ocean eolian dust preserved in deep sea sediment cores provides a valuable indicator of past atmospheric circulation and continental paleoclimate in order to identify the provenance of eolian dust nd and sr isotopic compositions and rb sr and rare earth element ree concentrations have been determined for the silicate fractions of deep sea sediments from the north and central pacific ocean different regions of the pacific ocean are characterized by distinct air borne inputs producing a large range in end 10 to 1 stsr 86sr 0 705 0 721 la yb 5 15 eun eu 0 6 1 0 and sr nd 4 33 the average nd isotopic composition of pacific deep sea sediments eno 6 is more radiogenic than the average from the atlantic ena 8 in contrast the average 1475m 14and ratio for pacific sediments 0 114 is identical to that of atlantic sediments and to that of global average riverine suspended material the values of ena and 147sm 144nd are positively correlated for the pacific samples but negatively correlated for atlantic samples reflecting a fundamental difference between the dominant components in the end members with radiogenic nd island arc components in the pacific and lree enriched intraplate ocean island components in the atlantic samples from the north central pacific have distinctive unradiogenic end values of 10 87sr 86sr 0 715 high la yb 12 and low eun eu 0 6 and sr nd 3 6 these data are virtually identical to the values for loess from asia and endorse the use of these sediments as indicators of asian paleoclimate and paleowind directions island arc contributions appear to dominate in the northwest pacific resulting in higher end 1 to 1 and lower 87sr 86sr 0 705 and la yb 5 sediments from the eastern pacific tend to have intermediate sr and nd isotopic compositions but regionally variable sr nd and ree patterns they appear to be derived from the west margin of the north and south american continents rather than from asia our results confirm that dust provenance can be constrained by isotopic and geochemical analyses which will facilitate reconstructions of past atmospheric circulation and continental paleoclimate

accretion of asian dust to hawaiian soils isotopic elemental and mineral mass balances hawaiian soils contain a mixture of material derived from in situ weathering of parent material plus atmospheric inputs including sea salt aerosols and asian dust we use soil mineralogy and radiogenic isotope geochemistry sr and nd to evaluate the impact of asian dust on a chronosequence of hawaiian soils dust becomes an important constituent of soils 20 ky and older near surface 50 cm depth horizons contain as much as 30 quartz a mineral absent from local parent material basaltic sr and nd isotope signatures in these horizons have been completely overprinted by asian dust signatures with 87sr 86sr ratios as high as 0 723 and end values as low as 7 ree patterns in these soils are indistinguishable from that of average upper continental crust quartz abundance and nd isotopes provide two independent tracers of long term dust additions to the chronosequence soils the two tracers indicate a minimum long term average dust accretion rate of 125 mg cm 2 ky 1 at the 150 ka chronosequence site roughly a factor of three higher than holocene dust accumulation rates estimated from north pacific sediment cores we find that the mass of dust preserved in these soil profiles does not increase with age in soils 150 ka and older requiring a loss mechanism for accreted dust on the basis of the geomorphic stability of these sites observed preferential loss of dust derived mica relative to quartz and estimates of soil si leaching rates we argue that chemical weathering is the dominant loss mechanism for dust from these soils dust has a profound effect on the budgets of elements that are susceptible to leaching losses dust becomes the dominant source of soil nutrients si and p in the oldest most intensely weathered soils we calculate a dust derived p input flux of 0 8 mg cm 2 ky 1 and a dust derived si input flux of 35 mg cm 2 ky 1 si leaching fluxes are high 1400 mg cm 2 ky 1 in the youngest 2 ka soils and drop systematically with soil age to a value that closely balances the dust derived si input flux by 4100 ka extremely refractory elements such as nb which are concentrated in soils by residual enrichment processes are much less readily impacted by dust addition although dust has had a pronounced impact on sr and nd isotopic budgets and on soil mineral composition at the 150 ka site dust cannot have contributed 4 of the total nb contained in this soil profile

geochemical tracers of northern portuguese estuarine sediments on the shelf the northern portuguese coastal zone is drained by large iberian rivers along which there is intensive industrial agricultural and urban activity offshore of the two main river basins of the douro and minho two fine grained sedimentary formations can be characterised a geochemical study of this sediment cover has been performed focussing in particular on the fine deposits and the adjacent estuaries the chemical composition of superficial sediments collected from the northern portuguese shelf and from the river basins of the minho and douro rivers was determined for major minor and trace elements the rare earth elements ree composition was also determined in selected samples statistical analyses of these data for the shelf sediments allow us to identify elements with similar behaviours and the different sediment types along the shelf and to evaluate of their origins downcore profiles of the chemical composition of the fine sediments reveal no evidence for changes induced by recent human activities to assess the influence of the rivers on the fine sedimentary formations the elemental distribution patterns of selected sediments have been compared with the estuarine sediments lithogenic elements composition normalised to al and the shale normalised ree distributions showed there are similarities between the douro river sediments and the sediment composition of the douro and galicia mud patches however the galicia mud field showed no relationship in its chemical composition to sediments derived from the minho river nor was any evidence for heavy metal contamination originating from the douro estuary detected in anthropogenic element al ratios in the shelf sediments this may be because of processes associated with resuspension complexation and bioturbation that occur during sediment transport and deposition nevertheless the douro river seems to be the main continental source of fine sediments being deposited on the northern portuguese shelf

an integrated model for transitional pressure solution in sandstones abstract a key aspect of the deformation of sedimentary rocks during diagenesis is pressure solution however it is often not clear why some rocks of a given mineralogy depth and pressure exhibit a great deal of pressure solution while very similar rocks under similar conditions do not to address such difficulties which we believe arise from the natural non linear physico chemical processes a quantitative model for pressure solution applied to sandstones has been developed this model subsumes various factors 1 pressure temperature and burial rate 2 grain size shape and packing of the mineral grains 3 the variability of water film thickness and coefficient of diffusion between any two grains in contact as a function of stress across the contact pore fluid pressure salinity ph and temperature in this study we distinguish several types of surface sites over quartz grains in a sandstone with corresponding differences in chemical potential thus allowing the diffusive transfer of matter from one site to another the contact between two grains is divided into two parts the actual true contact between two grains is a site of water film diffusion and the inclusions inside the contact the free face inclusion contacts are sites of free face pressure solution on the pore surface site precipitation occurs it is shown that a kinetics transition from a reaction limited deformation to a diffusion limited deformation occurs in the upper crust a geometric transition occurs too due to the textural evolution of the rock with deformation the main goal of this paper is to show the dynamics of the shifting importance of actual and free face inclusion contacts using a unified model including both features the result is a predictive model for porosity variations with depth due to pressure solution in sandstones

water and sediment discharge from small mountainous rivers taiwan the roles of lithology episodic events and human activities national science council of taiwan nsc96 2628 m 001 028 u s national science foundation and naval oceanographic office

neogene quaternary tectonic stratigraphy of the eastern southern alps ne italy abstract in order to reconstruct the neogene quaternary tectonic stratigraphy of the eastern southern alps the late tortonian lower pleistocene foredeep clastic sequences cropping out in the veneto and friuli piedmont areas have been extensively investigated focusing on the contractional features observed in the frequent conglomerate layers pitted pebbles the eastern southern alps is the result of a typical polyphase tectonic activity initiated in late oligocene characterised by the occurrence of several non coaxial stress regimes based on careful analyses of the pebbles surfaces shape and orientation of the indented features and following a systematic and statistical approach the mean orientation of the maximum compressive stress axis 1 has been obtained for more than 30 sites of measurements along the ca 120 km long investigated piedmont area the affected lithostratigraphic units and the orientation pre versus post tilting of the stereonets density peaks make it possible to recognize four distinct deformational events and characterize them in terms of mean 1 direction and timing late tortonian 1 313 00 late messinian early pliocene 338 04 late pliocene 314 03 and early middle pleistocene 160 03 the tectonic stratigraphy of the eastern southern alps during the last ca 10 ma shows the occurrence of several variations of the stress field characterized by a repeated oscillation of the 1 axis between an nnw sse and nw se directions twist tectonics taking also into account literature data about older deformational events chattian burdigalian and serravallian tortonian we analyse the neogene quaternary tectonic evolution in the frame of the central mediterranean realm and compare it with the convergence direction between the adria africa and europe lithospheric plates we show that compressional directions within the eastern southern alps are basically governed by the remote plate convergence though since late messinian the approaching northern apennines started to play a crucial role within the investigated area alternating short lived phases 1 2 ma of coupling and decoupling along the basal detachment of the apennines accretionary wedge probably caused temporary perturbations of the local stress field and complex accommodation structures in this region of ongoing crustal collision

present state of tectonic stress of the friuli area eastern southern alps stress orientations are determined for the friuli area from focal mechanisms using the inversion technique of gephart and forsyth 1984 the data consist of 244 fault plane solutions selected for the period 1988 1995 where the data coverage was poor this period was extended to 1978 1996 local magnitude ranges from 2 0 to 4 3 and the depths extend from 4 to 16 km the friuli area is subdivided into five seismotectonic zones on the basis of tectonic characteristics seismic activity and focal mechanisms and for each zone a stress tensor is determined the results show that the active tectonic stress in the friuli area is heterogeneous and conditioned by the complex structural pattern which is characterized by two indented tectonic wedges the western and central parts of the area are mainly affected by a compressional state of stress while in the eastern part a strike slip state of stress prevails the orientation of the principal stresses varies from the western to the eastern part of the area and differences are also noticeable with depth in the central part of the friuli area the maximum compressional stress is n s trending at shallow depths 10 km changing to nw se at deeper levels the maximum compressional stress is nw se oriented in the western part while in the eastern part it is n s oriented

from middle jurassic heating to neogene cooling the thermochronological evolution of the southern alps abstract the dolomite region is located in the southern alps which were affected by mesozoic extensional tectonics and by consequent thermal perturbations in this work vitrinite reflectance and apatite fission track analysis are used to estimate the thermal evolution these methodologies have been applied to the permo mesozoic succession which crops out along the transalp seismic profile the regional distribution of the organic matter maturity seems to be mainly controlled by different burials reached during the norian liassic extensional phase in connection with high heat flow values the best solutions obtained from thermal modelling of both vitrinite and fission track data suggest that peak of high heat flow occurred during bajocian bathonian ages when western tethys was characterized by intrusions of gabbros and plagiogranites and extrusion of tholeiite basalts this time coincides with the onset of the drifting phase and related thermal subsidence the following thermal relaxation occurred during continuous sedimentation and the maximum burial does not coincide with peak temperatures cooling history has been carefully analysed through apatite fission track data on samples collected close to the valsugana overthrust which document an important exhumation event at about 10 ma the related erosion has been analysed through the combined use of arenite petrography and fission track analysis on detrital samples of the veneto foredeep succession which represents the storage of detritus during tertiary these data confirm that after serravalian the southalpine domain and related covers were affected by subaerial erosion

composition of water and suspended sediment in streams of urbanized subtropical watersheds in hawaii abstract urbanization on the small subtropical island of oahu hawaii provides an opportunity to examine how anthropogenic activity affects the composition of material transferred from land to ocean by streams this paper investigates the variability in concentrations of trace elements pb zn cu ba co as ni v and cr in streams of watersheds on oahu hawaii the focus is on water and suspended particulate matter collected from the ala wai canal watershed in honolulu and also the kaneohe stream watershed as predicted suspended particulate matter controls most trace element transport elements such as pb zn cu ba and co exhibit increased concentrations within urbanized portions of the watersheds particulate concentrations of these elements vary temporally during storms owing to input of road runoff containing elevated concentrations of elements associated with vehicular traffic and other anthropogenic activities enrichments of as in samples from predominantly conservation areas are interpreted as reflecting agricultural use of fertilizers at the boundaries of urban and conservation lands particulate ni v and cr exhibit distributions during storm events that suggest a mineralogical control principal component analysis of particulate trace element concentrations establishes eigenvalues that account for nearly 80 of the total variance and separates trace elements into 3 factors factor 1 includes pb zn cu ba and co interpreted to represent metals with an urban anthropogenic enrichment factor 2 includes ni v and cr elements whose concentrations do not appear to derive from anthropogenic activity and is interpreted to reflect mineralogical control another albeit less significant anthropogenic factor includes as cd and u and is thought to represent agricultural inputs samples collected during a storm derived from an offshore low pressure system suggest that downstream transport of upper watershed material during tradewind derived rains results in a 2 3 fold dilution of the particulate concentrations of pb zn and cu in the ala wai canal watershed